Short Textbook of Endodontics 9789352501212, 9352501217

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Aarti Daswani

Foreword Sharad Kokate

Short Textbook of

Endodontics

Short Textbook of

Endodontics Aarti Daswani  BDS Dental Surgeon and Private Practitioner Divine Smiles Dental Clinic Andheri (East), Mumbai, Maharashtra, India Foreword

Sharad Kokate

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Website: www.jaypeebrothers.com Website: www.jaypeedigital.com © 2016, Jaypee Brothers Medical Publishers The views and opinions expressed in this book are solely those of the original contributor(s)/author(s) and do not necessarily represent those of editor(s) of the book. All rights reserved. No part of this publication may be reproduced, stored or transmitted in any form or by any means, electronic, mechanical, photo­copying, recording or otherwise, without the prior permission in writing of the publishers. All brand names and product names used in this book are trade names, service marks, trademarks or registered trademarks of their respective owners. The publisher is not associated with any product or vendor mentioned in this book. Medical knowledge and practice change constantly. This book is designed to provide accurate, authoritative information about the subject matter in question. However, readers are advised to check the most current information available on procedures included and check information from the manufacturer of each product to be administered, to verify the recommended dose, formula, method and duration of administration, adverse effects and contra­indications. It is the responsibility of the practitioner to take all appropriate safety precautions. Neither the publisher nor the author(s)/editor(s) assume any liability for any injury and/or damage to persons or property arising from or related to use of material in this book. This book is sold on the understanding that the publisher is not engaged in providing professional medical services. If such advice or services are required, the services of a competent medical professional should be sought. Every effort has been made where necessary to contact holders of copyright to obtain permission to reproduce copyright material. If any have been inadvertently overlooked, the publisher will be pleased to make the necessary arrangements at the first opportunity. Inquiries for bulk sales may be solicited at: [email protected] Short Textbook of Endodontics First Edition: 2016 ISBN  978-93-5250-121-2 Printed at

Dedicated to My Parents (Mr Rupchand and Mrs Sangita Daswani)

Foreword It is a proud moment and a great pleasure to see one of our talented graduates writing the Short Textbook of Endodontics. Aarti Daswani’s strong will and passion for last several years after graduation has given a wonderful shape to the final content of this textbook. Aarti Daswani has made an excellent attempt at making the indispensable knowledge of Endodontics easier to understand for the students as well as clinicians. The unique feature of this textbook is the mind-maps in each chapter, which should help in summarizing and memorizing during examinations. The meticulously prepared content will further help as an invaluable reference for the students as well as clinicians. The language of the textbook is very simple and the diagrammatic representation makes it simpler. I am confident that the book will go a long way in clearly simplifying and developing interest amongst the readers.

Sharad Kokate Dean, Professor of Conservative Dentistry and Endodontics Yerala Medical Trust’s Dental College and Hospital, Kharghar, Navi Mumbai, Maharashtra, India Vice President Maharashtra State Dental Council Mumbai, Maharashtra, India

Preface What led me to the idea of writing Short Textbook of Endodontics is an astonishing realization that the field of Endodontics has undergone sea changes in the last few years. Endodontic treatment has come a long way from what it was till about two decades ago. Not only dental materials and instruments have become technically superior, but also the concepts, procedures and attitudes of clinicians have acquired a modern outlook. Technology has made Endodontic treatment swift, convenient, easier and interesting. In addition to incorporating the new developments in Endodontics, Short Textbook of Endodontics has been designed to cover each and every aspect of Endodontics in a concise yet comprehensive manner. Considering the fact that time is a critical factor in today’s competitive and busy world, there is no doubt that reading big fat textbooks to get through the examinations is an uphill task for the students. However, remembering the information is important and this requires repeated reading and revision. This book is expected to make reading Endodontics interesting and a fun-filled experience through the use of different memory improvement techniques. Purpose of this book is not to serve as replacement of standard textbook but to complement the textbook and be used solely for revision.

Thus, Short Textbook of Endodontics is a:

•

Memory aid: That helps you memorize, retain and reproduce the required information of the basic texts.

•

Rapid revision guide: That helps you save time and quickly revise the subject while preparing for the examinations.

Unique feature of this book is inculcating learning through “Mind-maps”, a concept introduced by Tony Buzan, popular Psychology author and television personality. A mind-map is a diagram used to visually organize information. This diagramming tool can be used to generate, visualize, structure and classify ideas and as an aid to studying and organizing information in a concise yet comprehensive manner. Mind-maps used in this book act as a quick learning aid to the ever-expanding world of Endodontics. Of course, it goes without saying that mind-maps are just meant to help the reader remember all relevant points of a topic and should not be reproduced in the examination papers as the same may not be acceptable. The general practitioners can use this book to train their mind to remember what next in the course of performing Endodontic procedures. The book will serve as a foundation for sound theoretical knowledge, based on which practitioners can perform better in a given clinical situation. Writing this book would not have been possible without contributions from multitude of people including my college teachers, eminent Endodontists and general dentists, computer experts and artists. “If you cannot explain it simply, you do not understand it well enough”—Albert Einstein. Through this book, I have made a sincere attempt to simplify the subject of Endodontics based on my understanding and clinical experience of seven years. I hope it will be useful to the readers. I look forward to your suggestions, contributions and comments on Short Textbook of Endodontics (First edition) for future additions and improvements.

Aarti Daswani

Acknowledgments First and foremost, I would like to express my heartfelt gratitude to my Satguru and God Almighty for all their blessings, unconditional love and wealth of knowledge they have showered on me and continue to shower on me every single day. My sincere thanks to my parents for being a constant source of support and encouragement in all my endeavors and for all their love and sacrifices. Special thanks to my younger sister Yogi, for introducing me to Tony Buzan’s concept of ‘Mind-maps’ and to my elder sister Lata, for being my critic, inspiration and guide throughout the compilation of Short Textbook of Endodontics. Special thanks to my dear friends Mamta, Samta, Jayshree, Amita and Kanika for their constant motivation and encouragement that inspired me to move faster towards realizing my dream of being an author. I am grateful to my assistants in clinical practice, Maya and Kalpana, for their support and cooperation during the compilation of the book. I would like to thank Shri Jitendar P Vij (Group Chairman), Mr Ankit Vij (Group President), Mr Tarun Duneja (Director– Publishing), Mr KK Raman (Production Manager) and the entire team of M/s Jaypee Brothers Medical Publishers (P) Ltd, New Delhi, India, for believing in my convictions and giving me an opportunity to write this book and allowing me to make a small contribution to dental profession in my own way. Special thanks to Mr Ramesh Krishnamchari and Mr Sabarish Menon (Author Coordinators), Mr Sunil Dogra (Production Executive) and Mr Mohit Bhargava (Production Coordinator), of M/s Jaypee Brothers, for guiding me throughout the project. My heartfelt thanks to Dr Sharad Kokate, Dean, Yerala Medical Trust’s (YMT) Dental College and Hospital, Kharghar, Navi Mumbai, for giving me permission to use innumerable reference books from college library and for his constant support, guidance and encouragement throughout the compilation of the book. He also very kindly agreed to write the foreword for the book. I am truly indebted to my teacher Dr Mrunalini Vaidya, who is a great Endodontist, an excellent academician and a Professor at YMT Dental College and Research Institute, Navi Mumbai, Maharashtra, India, for Conservative Dentistry and Endodontics. I take this opportunity to extend my deep gratitude to her for devotion of her time and dedicated efforts in critically evaluating each chapter and providing valuable suggestions to improve the book. My sincere thanks to Dr Vishal Rathod for creating amazing diagrams and simplified illustrations for the book. I am grateful to Dr Manoj Ramugade, MDS, Conservative Dentistry and Endodontics, teacher at Nair Hospital Dental College, Mumbai, Maharashtra, India, for his valuable contribution towards the layout of the book. He also helped me with critical evaluation of initial chapters and gave valuable suggestions to improve the contents including contribution by way of some very good photographs and radiographs for the book. I am thankful to my friend Dr Suvarna Kondawale for going through the chapters and providing suggestions for improvement. Many thanks to Dr CR Suvarna for providing few photographs of Endodontic equipment and also his case photographs. I am really grateful to Dr Ajay Bajaj for his critical evaluation and valuable suggestions as well as encouragement and support including contribution in the form of his case radiographs for the book. Many thanks to Dr Ashwin Jawdekar for providing useful information, case radiographs and photographs for the three chapters namely Pediatric Endodontics, Pulp Therapies and Management of Dental Traumatic Injuries. My heartfelt thanks to Dr Mansi Shah for contributing valuable information on Cone Beam Computed Tomography (CBCT) scans in the chapter Diagnosis and Diagnostic Aids in Endodontics and for providing her case radiographs and CBCT scans for the book.

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My deep appreciation to Dr Shivani Bhatt, a dynamic and enthusiastic dentist for contributing her case photographs and radiographs for the book. My humble gratitude to Dr Roheet Khatavkar, an Endodontist par excellence, who uses all the latest available equipment and instruments in Endodontics selectively for his cases, for contributing valuable information and his case radiographs. I am grateful to Dr Nilesh Kadam for contributing his case radiographs for the book. I am thankful to Dr VS Mohan, Dr Mukul Dabholkar, Dr Rajesh Podar, Dr Raunak Rai, Dr Paresh Dodhiwala, Dr Samir Khaire, Dr Rajesh Shivhare, Dr Ritesh Mahashabde, Dr Sonam Singh, Dr Mugdha Mitkar, Dr Nomal Sheth and Dr Dharna Parekh for their contribution, help and support for the book. I am grateful to Dr Chetan Shah for his sincere and enthusiastic support and encouragement, which helped me give a new dimension to the book. My special thanks to Dr Cliffton Ruddle for giving me permission to use photographs from his inventions in Endodontics. Also special thanks to American Association of Endodontists for giving me permission to reprint the Endodontic case difficulty forms. Heartfelt thanks to Dr Priyanka Karande and Dentsply company for providing me with high resolution photographs of Dentsply Endodontic products; to Mr Amit Borkar and Dr Raghu for providing me with high resolution images of the Sybron Endo products; to Mr Guru and Micro-Mega company for providing me with high resolution images of the Micro-Mega Rotary Endodontic system; to Re Dent Nova company and Dr Ajit Jha for valuable information and photographs of the latest self-adjusting file system. My sincere gratitude to Mr A Sawant for preparing the initial computerized typescripts of the entire textbook.

Contents 1. Introduction

1

2. The Dental Pulp and the Periradicular Tissues

5

What is the Scope of Endodontics?  1;  What are the Aims and Objects of Endodontics?  2; What are the Changes and Recent Advances that have Occurred in the Field of Endodontics?  2 What is the Dental Pulp and the Dentin-Pulp Complex?  5;  What are the Special Characteristics of the Dental Pulp as Connective Tissue?  6;  How is the Dental Pulp Formed?  6;  What are the Histologic Features of Dental Pulp?  8;  What is the Blood Supply of the Pulpal Tissues?  11;  What is the Nerve Supply of Pulpal Tissues?  12;  What is the Lymph Supply of Pulpal Tissues?  12;  What are the Functions of the Pulp?  13;  What is the Morphology and Histology of Periradicular Tissues?  14

3. Morphology and Internal Anatomy of the Root Canal System

19

4. The Pulpal Reactions to Caries and Dental Procedures

50

5. Diseases of the Pulp and the Periradicular Tissues

62

6. Endodontic Microbiology

83

7. Diagnosis and Diagnostic Aids in Endodontics

98

What are the Anatomic Components of the Root Canal System?  19;  What are the Regressive Changes that Occur in the Anatomy of Root Canal System?  21;  What are the Different Types of Root Canal Systems in any Root?  21;  What is the Anatomy of the Apical Portion (Apical 1/3rd) of the Root Canal?  25;  Which are the Anatomic Complexities that can Occur in Root Canal System?  26;  What is Isthmus and What is its Role During Endodontic Surgical Procedure?  29;  Role of Isthmi in Endodontic Surgical Procedure  29;  What are the Possible Developmental Anomalies and Variations in the Anatomy of Root Canal System?  29;  What is the Morphology of the Root Canal System of the Individual Teeth?  32 How is the Response of Dental Pulp Unique and Different from other Connective Tissues of The Body?  50;  Which are the Different External Stimuli that can Affect the Dental Pulp?  50; How does the Pulp React to Dental Caries?  50;  How does the Pulp React to Dental Procedures?  54 What are the Possible Causes of Diseases of Dental Pulp?  62;  How does the Pulp React to Different Direct and Indirect Stimuli and how is the Response Unique?  66;  How do we Classify the Diseases of Dental Pulp?  66;  What are the Different Features of the Diseases of the Dental Pulp?  67;  What are the Causes of Diseases of the Periradicular Tissues?  71;  How do we Classify the Diseases of Periradicular Tissues?  72; What are the Different Features of the Diseases of Periradicular Tissues of Endodontic Origin?  72; What is the Pathogenesis of Primary Apical Periodontitis?  81 What is the Basis of Focal Infection Theory and why is it Totally Rejected Today?  83;  What are the Pathways or Portals of Entry of Microorganisms in the Pulp?  84;  What is the Microbial Flora of Root Canal?  84; Which are the Types of Endodontic Infections?  86;  What is the Role of Microbial Virulence and Host Response in the Pathogenesis of Disease?  88;  What are the Methods for Detection, Identification and Examination of Microbes from a Root Canal?  89;  What is the Biofilm and What is its Significance in Endodontics?  92 What is Diagnosis and how to be a Successful Diagnostician?  98;  What are the Steps to be Followed to Arrive at a Correct Diagnosis?  98;  Step 1: Case History Taking  99;  Step 2: Clinical Examination  104;  Radiographs  109;  Requirements of a Good Radiograph  111;  Limitations or Drawbacks of Radiographs  111;  Radiation Safety  111;  Film Holders  115;  Cone Beam Computed Tomography (CBCT) for Endodontics 118;  Step 3: Diagnostic Tests  118;  Special Tests  123; Step 4: Arriving at an Accurate Endodontic Diagnosis  129

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8. Rationale of Endodontic Therapy

130

9. Case Selection and Treatment Planning

139

Which were the Proposed Theories of Spread of Infection that Developed into the Modern Philosophy of Endodontics?  130;  How do the Dental Biologic Tissues React to Noxious Stimuli?  131;  Why is the Inflammatory Response in Connective Tissue of Dental Pulp Different from other Parts of Body?  131; What are the Tissue Changes that Occur during Inflammation?  131;  What Tissue changes occur following Inflammation?  135;  What is the Role of Immunity in Endodontics?  135; What are the Zones of Reaction of Periradicular Tissues and Endodontic Implications?  136 How to Evaluate a Case for Treatment?  139;  What are the Factors to be Considered for Case Selection for Root Canal Treatment?  141;  What are the Indications and Contraindications of Root Canal Treatment?  143;  How to Develop an Endodontic Treatment Plan?  145;  How to Assess Difficulty of an Endodontic Case?  146;  AAE Endodontic Case Difficulty Assessment Form and Guidelines  147

10. Principles of Endodontic Treatment

150

11. Endodontic Armamentarium: Instruments, Materials and Devices

158

12. Asepsis and Sterilization of Endodontic Instruments

192

13. Endodontic Access Cavity Preparation

199

14. Cleaning and Shaping of the Root Canal System Including Working Length Determination

231

What are the Principles of Endodontic Treatment?  150 What Changes have Occurred in the Endodontic Armamentarium in the Practice of Modern Endodontics?  158;  What are the Devices used for Enhanced Vision, Illumination and Magnification?  159; What are the Instruments, Materials and Devices used as Diagnostic Aids in Endodontics?  161;  What is the Armamentarium for Administration of Local Anesthesia?  163;  What are the Materials used for Isolation of Endodontic Field?  163;  What is the Armamentarium Needed for Access Cavity Preparation of Root Canal?  163;  What are the Instruments and Devices for Determination of Working Length?  167; What are the Materials used for Disinfection of the Root Canal?  169;  What are the Instruments and Devices used for Root Canal Preparation?  169;  Hand-Operated Instruments  170;  Engine-Driven Instruments  177;  Ultrasonic and Sonic Instruments  178;  Nickel-Titanium Hand and Rotary Instruments  179;  What are the Instruments used for Obturation of Root Canals?  186;  What are the Instruments and Devices used for Removal of Root Canal Fillings and other Obstructions in Root Canal?  187;  What are the Materials used as Temporary Restorations?  189;  What is the Armamentarium for Periradicular Surgery?  190;  What are the Materials used for Post-Endodontic Restoration?  190; What is the Role of Laser Device in Endodontics?  190 Why is Effective Infection Control Important in Endodontics?  192;  How to Achieve Effective Infection Control in Dental Practice?  193;  What is Sterilization and Disinfection?  195;  How to take Proper Care of Endodontic Instruments?  196;  What are the Commonly Employed Methods of Sterilization/ Disinfection of Various Endodontic Instruments?  198 What is Endodontic Triad?  199;  What is Coronal Access Cavity Preparation of the Root Canal?  199; What are the Objectives of Access Preparation?  200;  What are the Principles of Endodontic Access Cavity Preparation?  200;  What are the Guidelines to be followed for an Optimum Access Cavity Preparation?  201;  What is the Armamentarium Needed for Access Cavity Preparation?  206; Which are the Steps of Access Cavity Preparation?  207;  What are the Specific Features of Access Preparation of Individual Teeth and Possible Errors Related to Them?  211;  Which are the Challenging Access Cavity Preparations and How to Deal with them?  226;  What Errors can Occur During Access Cavity Preparation?  228

What is Cleaning and Shaping of Root Canals?  231;  What are the Objectives of Cleaning and Shaping of Root Canals?  232;  Which are the Important Numerical Concepts in Root Canal Preparation and how

Contents

xv

to Determine them?  233;  What are the Current Concepts and Terminology for Root Canal Preparation?  241;  What are the Different Instrument Motions for Effective Shaping of Root Canals?  243;  What are the Requirements before Starting Canal Preparation?  244;  Which are the Different Root Canal Preparation Techniques?  244;  What are the Precautions to be taken during Instrumentation?  262;  What are the Procedural Errors that can Occur during Root Canal Preparation?  263

15. Disinfection of the Root Canal System

264

16. Obturation of Root Canal System

280

17. Drugs or Medicaments used in Endodontic Treatment

311

18. Single Visit Endodontics

320

19. Endodontic Emergencies and Midtreatment Flare-Ups

323

20. Endodontic Mishaps: Management and Prevention

336

21. Restoration of Endodontically Treated Teeth

355

What is Disinfection of the Root Canal System?  264;  How to bring about Disinfection of the Root Canal System?  264;  Which are the Different Chemical Agents used for Disinfection of the Root Canal System?  265;  What is a Root Canal Disinfectant and What are its Requirements?  265;  Which are the Different Root Canal Irrigants?  265;  Different Root Canal Irrigants  267;  What is Smear Layer and how is it Managed in Endodontics?  271;  What are Intracanal Medicaments?  273;  What are the Methods of Activation of Irrigating Solutions in the Root Canal System?  276 What is Obturation of Root Canal?  280;  What are the Objectives of Obturation?  280;  When to do Obturation of the Root Canal?  281;  What should be the Apical Extent of Obturation?  282;  With what should we do Obturation?  282;  What are the Requirements for an Ideal Root Canal Filling Material?  283; Which are the Different Core Materials that can be used for Obturation?  283;  What are Root Canal Sealers and What are the Requirements of an Ideal Root Canal Sealer?  288;  What is the Purpose of using a Root Canal Sealer?  288;  How is the Sealer Placed in the Root Canal?  288;  Which are the Different Root Canal Sealers used in Obturation?  289;  Root Canal Sealers in Detail  289;  What is the Preparation for Obturation?  293;  How to do Obturation/which are the Different Techniques of doing Obturation?  294; How should an Ideal Obturation be?  308;  What can go Wrong in Obturation?  308; What is the Importance of Coronal Seal and How can we Enhance it?  309 How to Manage Fear and Anxiety in an Endodontic Patient?  311; Which are the Drugs or Medicaments used in Endodontics?  312;

What is Single Visit Endodontics?  320;  What is the Rationale for SVE?  320;  What are the Advantages and Disadvantages of SVE?  320;  What are the Possible Indications and Contraindications of SVE?  321; What are the Factors to be Considered for Case Selection for Doing SVE?  321;  What has Held Back SVE?  322 What is an Endodontic Emergency?  323;  What is Meant by the Terms ‘Hot Tooth’ and ‘ERCO’?  323; How to Make Correct Diagnosis in Case of Endodontic Emergencies?  324;  How do we Classify Endodontic Emergencies?  325;  Endodontic Emergencies in Detail  326;  Endodontic Emergencies before Treatment  326;  Interappointment Endodontic Emergencies  331;  Endodontic Emergencies after Treatment  335 What are Endodontic Mishaps?  336;  How do we Classify Endodontic Mishaps?  336; Endodontic Mishaps in Detail  337 How are Endodontically Treated Teeth Different?  355;  What is Expected Out of Postobturation Restoration?  357; What is Direct ‘Coronal-Radicular’ Postobturation Restoration?  357;  What are the Factors to be Considered for a Postendodontic Restoration?  357;  What are the Ideal Requirements of a Restorative Material to be used for Postendodontic Restoration?  358;  What are the Restorative Options for a Postendodontic Restoration?  359;  What is Post and Core Restoration?  360;  What is “Ferrule Effect” and “Biologic Width”?  361; What are the Indications for Using Posts?  362;  What are the Required Clinical Characteristics of Posts?  362;  What are the Different Types of Posts?  362;  What are the Clinical Parameters for Post

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Selection?  365;  What are the Required Physical Characteristics of the Core?  367;  What are the Different Types of Core Materials?  367;  What is the Technique of Fabrication of Foundation Restoration?  369;  What are the Causes of Failure of Post and Core Restorations?  372

22. Endodontic Failures and Nonsurgical Endodontic Management

373

23. Management of Discolored Teeth

382

24. Management of Dental Traumatic Injuries

401

25. Endodontic-Periodontal Inter-Relationships

414

26. Surgical Endodontics

425

27. Pulp Therapies

439



What is the Outcome of Endodontic Treatment?  373;  What are the Measures to be Employed to Improve the Rate of Success of Treated Endodontic Cases?  373;  What are the Causes of Endodontic Failures?  374;  How do you Diagnose Post-Treatment Disease?  375;  What is the Treatment Plan for the Patient with Post-treatment Disease?  377;  What are the Indications and Contraindications of Endodontic Retreatment?  377;  What are the Factors to be Considered for Endodontic Retreatment?  377;  What are the Steps of Nonsurgical Endodontic Retreatment?  377;  What is the Prognosis of Endodontic Retreatment?  381 What are the Causes of Tooth Discoloration?  382;  What are the Different Methods of Management of Discolored Teeth?  383;  What is Bleaching of Teeth?  383;  Why Bleaching?  383;  What is the Chemistry and Mechanism of Bleaching?  384;  Etiology of Tooth Discoloration and its Management in Detail  384;  What are the Indications and Contraindications of Bleaching?  388;  Which are the Materials used for Bleaching?  388;  What is the Technique for Bleaching Vital Teeth?  389;  What are the Side Effects and Adverse Effects of Extracoronal Bleaching of Vital Teeth?  391;  What is the Technique for Bleaching Endodontically-Treated Teeth?  392;  What are the Side Effects and Adverse Effects of Intracoronal Bleaching of Endodontically Treated Teeth?  397;  How do we Restore Intracoronally Bleached Endodontically Treated Tooth?  398;  What is Enamel Microabrasion?  398;  What is the Role of Veneers and Crowns in Management of Discolored Teeth?  400 What are the Unique Aspects of Dental Trauma?  401;  What are the Consequences of a Dental Traumatic Injury?  401;  How do we Classify Traumatized Teeth?  402;  How do we Make Diagnosis in Case of Dental Traumatic Injuries?  403;  What are the Factors to be Considered for Treatment of Traumatized Teeth?  404;  What are the Different Dental Traumatic Injuries and Their Management?  404;  Requirements for Success of Vital Pulp Therapy in Case of Traumatized Teeth  405;  Pulp Therapies in Traumatized Teeth  405 How are Endodontic and Periodontal Tissues and their Diseases Inter-Related?  414;  What are the Etiologic Factors and Contributing Factors causing Endodontic-Periodontal Diseases?  415;  How do we Classify Endodontic-Periodontal Lesions?  416;  How to Detect Endodontic Periodontal Lesions?  417;  What Differential Diagnosis will you Consider when you see Features of both Endodontic and Periodontal Lesions?  418;  Which are the Different Types of Endodontic-Periodontal Lesions?  418;  What are the Treatment Alternatives in case of Endodontic-Periodontal Lesions?  422;  What is the Prognosis of a Tooth with both Endodontic and Periodontal Disease?  424 What is Endodontic or Periradicular Surgery and what are its Objectives?  425;  What are the Indications of Periradicular Surgery?  425;  What are the Contraindications of Periradicular Surgery?  426;  What is the Contemporary Classification of Endodontic Surgery?  427;  What are the Important Considerations while case Selection and Treatment Planning for Periradicular Surgery?  427;  What are the Basic Principles and Steps to be followed in Periradicular Surgery?  429 What is Vital Pulp Therapy?  439;  What are the Objectives of Vital Pulp Therapy?  439;  What are the Techniques and Materials used for Vital Pulp Therapy?  439;  What are the Hemostatic Agents and Antimicrobial Materials used in Vital Pulp Therapy?  446;  What is the Criteria for Case Selection for Vital Pulp Therapy?  446;  What is Apexification (Nonvital Pulp Therapy)?  446

Contents

xvii

28. Pediatric Endodontics

450

29. Geriatric Endodontics

468

30. Pathologic Tooth Resorption

474

31. Dentinal Hypersensitivity and its Management

482

32. Lasers in Endodontics

488

33. Endodontic Practice: Ethics and Legal Responsibilities

495

34. Regenerative Endodontics

500

Index

507

What is Pediatric Endodontics?  450;  What are the Objectives of Preserving Primary Teeth?  450; What are the General Features of Endodontic Treatment of Pediatric Patients?  450;  What are the Specific Morphologic Features of Teeth of Pediatric Patients?  450;  How to Establish a Correct Pulpal Diagnosis in Children?  453;  What is the Important thing you must Know about the Proximal Lesions in Primary Teeth?  455;  Which are the Different Pulp Therapies Performed in Children?  457;  Pulp Therapies for Primary Teeth  458;  Direct Vital Pulp Therapies  459;  Nonvital Pulp Therapy for Primary Teeth  463 What is Geriatric Endodontics?  468;  What is the Scope of Geriatric Endodontics?  468;  What is the Need for Geriatric Endodontics?  468;  What are the Specific Features of General Health of Older Patients?   469; What are the Regressive Changes that Occur in the Teeth with Increasing Age?  469;  What are the Specific Features of Teeth of Older Patients?   469;  Which Orofacial and Dental Signs and Symptoms are Elicited by Clinician to Derive Correct Diagnosis?  470;  What are the Different Diagnostic Tests?   470; How to Formulate Treatment Plan after making Correct Diagnosis in Geriatric Patient?  471; What are the Steps in Endodontic Treatment in Geriatric Patient?  471 What is Tooth Resorption?  474;  What is Mechanism of Tooth Resorption?  474;  What are the Etiologic and Stimulating Factors of Tooth Resorption?  475;  Which are the Types of Tooth Resorption?  475; Which are the Clinical and Radiographic Features of Different Types of Tooth Resorption and How to Manage Them?  476;  What are the Differences Between External and Internal Root Resorption?  480 What is Dentinal Hypersensitivity?  482;  What are the Different Hypotheses put Forward to Explain the Mechanism of Dentinal Hypersensitivity?  482;  What is the Incidence and Prevalence of Dentinal Hypersensitivity?  484;  What are the Predisposing Factors that cause Dentinal Hypersensitivity?  484; How to Diagnose Dentinal Hypersensitivity?  484;  How to Manage Dentinal Hypersensitivity?  484 What is Laser?  488;  What are the Properties of Lasers?  488;  What are the Components of Lasers?  488; What are the Modes of Laser Light Emission?  489;  How is the Laser Interaction with Biologic Tissues?  489; Which are the Types of Lasers?  490;  What are the Applications of Lasers in Endodontics?  491; What are the Advantages and Limitations of Using Lasers in Endodontics?  494 What is Dental Ethics?  495;  What are the Principles of Ethics?  495;  What is Standard of Care?  495; What is Dental Negligence and Malpractice?  496;  What are the Legal Responsibilities of the Clinician While Performing Endodontics?  497 What is Regenerative Endodontics?  500;  What is Tissue Engineering?  501;  What are the Mechanisms and Clinical Procedures Related to Regenerative Endodontics?   503;  What is the Triple Antibiotic Paste?  503; What are the Advantages and Limitations of Revascularization Procedure over Apexification Procedure for a Necrotic Immature Permanent Tooth with Open Apex?  503;  What are the Clinical Considerations for Regenerative Endodontics?  504;  What is the Protocol for Revascularization Endodontic Therapy?  504; What are the Clinical Measures for Assessment of Endodontic Revascularization Treatment Outcome?  505

CHAPTER

1

Introduction

This chapter gives an overview of the subject of Endodontics and its importance in the field of dentistry.  • • •

You must know What is the Scope of Endodontics? What are the Aims and Objects of Endodontics? What are the Changes and Recent Advances that have Occurred in the Field of Endodontics?

DEFINITION •

•

According to Grossman, Endodontics is that branch of dentistry that deals with the etiology, diagnosis, prevention and treatment of diseases of the pulp and periapical tissues compatible with good health. According to American Association of Endodontists, Endodontics is that branch of dentistry that is concerned with the morphology, physiology and pathology of human dental pulp and periradicular tissues. Its study and practice encompass the basic clinical sciences including biology of the normal pulp; the etiology, diagnosis, prevention and treatment of diseases and injuries of the pulp; and associated periradicular conditions.

WHAT IS THE SCOPE OF ENDODONTICS? 1. Diagnosis and management of oral/dental pain 2. Diagnosis and treatment of diseases of pulp and periradicular tissues. 3. Pulp therapies: i. Pulp capping—indirect pulp capping (IPC) and direct pulp capping (DPC) ii. Pulpotomy iii. Apexogenesis and apexification

Pulp capping and pulpotomy comes under vital pulp therapy (VPT) 4. The root canal treatment (RCT) or the Endodontic treatment 5. Nonsurgical retreatment of teeth that have undergone Endodontic failure (Re-RCT) 6. Post-obturation restoration (POR) including post and core built-ups 7. Bleaching of teeth 8. Treatment of traumatized teeth. For example, replantation of avulsed tooth 9. Age-specific Endodontics: i. Pediatric Endodontics ii. Geriatric Endodontics 10. Surgical Endodontics including apicoectomy, hemisection, Endodontic implants, etc.) 11. Research of newer biocompatible materials and techniques to make Endodontics more predictable. 12. Use of magnification in Endodontics such as dental operating microscope (DOM) to enhance efficacy of procedures (Microendodontics) 13. Use of other clinical adjuncts such as ozone therapy in Endodontics and lasers in Endodontics. Figure 1.1 shows a mind-map giving the scope of Endodontics in short.

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Fig. 1.1  Mind-map to remember the scope of Endodontics

WHAT ARE THE AIMS AND OBJECTS OF ENDODONTICS? Schilder stated goals of Endodontics: “Root canal systems must be cleaned and shaped to receive a three-dimensional hermetic (fluid-tight seal) filling of the entire root canal space.” “The logical goal of Endodontic treatment is to eliminate or substantially reduce the microbial population within the root canal system and to prevent reinfection by a tight seal of the root canal space.” (PNR Nair, Pathways of Pulp, 9th edn. p.573).

The aims and objects of Endodontics can be summarized as given in Figure 1.2. (Remember the mnemonic: P3 R3 ESS).

WHAT ARE THE CHANGES AND RECENT ADVANCES THAT HAVE OCCURRED IN THE FIELD OF ENDODONTICS? In the last 2–3 decades, lot of advances have taken place in the art of Endodontics and science of Endodontology. Epidemiological studies suggest that the percentage of teeth that can be retained through contemporary Endodontic

Introduction

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Fig. 1.2  Aims and objects of Endodontics

therapy is rising well above 90%. Millions of teeth are being saved and then successfully restored to their full functional and esthetic value. Sea changes in Endodontics: There have been major changes in the practice of Endodontics. Although goals

to be achieved remain same but ‘How’ these goals can be achieved efficiently, effectively and without much discomfort to the patient in as less time as possible, has led to a lot of research in this field. Few examples of change in Endodontics are listed in Table 1.1. These have been explained in detail in the respective chapters.

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TABLE 1.1  Endodontics—Past and Present Changes in

From past → to → present day Endodontics

Diagnostic aids

• Conventional radiographs → Enhanced imaging with the help of digital radiography (2-dimensional) and CBCT scans (3-dimensional) • Conventional methods of testing Pulp vitality → Improved methods such as laser Doppler flowmetry (LDF), pulse oximetry vitality scanner, etc.

Visualization

Naked eye vision → Enhanced vision with magnification using loupes, dental operating microscope (DOM) with and without illumination, Endoscope and Orascope

Endodontic instruments

Made of carbon steel → Made of stainless steel (improved quality) → Made of nickel -titanium multitapered instruments (different shapes)

Instrumentation

Using manual (hand) instruments → Engine-driven nickel-titanium rotary instruments combined with hand instrumentation → other newer ways of instrumentation

Instrumentation technique

Conventional → Step-back → Crown-down approach

Working length and detection of apical constriction (Minor apical diameter)

Tactile sensation → Radiographs → Electronic apex locators combined with radiographs

Irrigation of root canals

Use of syringe-needle → Improved delivery systems, use of ultrasonic tips, EndoVac irrigation system and other newer irrigation systems. One of the recent advances include self-adjusting file (SAF) system, in which cleaning, shaping, irrigation and agitation of the irrigant are achieved simultaneously

Obturation materials

•  Core materials: Silver points → Gutta-percha → Thermoplasticized gutta-percha: Devices such as System-B, Touch-n-heat, Obtura II etc. → Resilon (resin-based) • Sealers: Zinc oxide eugenol sealers → Eugenol-free calcium hydroxide and other sealers → Epoxy resinbased sealers, methacrylate resin-based sealers

Improved biocompatible materials

• Calcium hydroxide and other repair materials → mineral trioxide aggregate (MTA) • MTA is a root canal repair material that has made perforation repair and apexification possible even in the presence of moisture

Surgical Endodontics

Conventional Endodontic surgery → Microsurgical Endodontics Microsurgical Endodontics is a predictable option due to: • Use of microscope (good magnification and illumination) • Use of ultrasonic tips • Use of MTA as retrograde filling material • Microinstruments

Newer devices and equipment

•  Retreatment: Use of hedstrom files to remove old root canal fillings → Use of DOM and improved devices and instruments for retreatment including: –  Specialized kit for gutta-percha removal – Devices to retrieve obstructions such as separated instruments, posts, foreign objects, etc. For example, Brassler Endo Extractor kit and Masserann kit, Guttapercha removal rotary file systems such as D1, D2 and D3, Postremoval system (PRS) kit, etc. •  Introduction of lasers in Endodontics

Other advances

• Use of saliva for diagnosis and DNA information through biomarkers • Tissue engineering • Tissue regeneration

BIBLIOGRAPHY 1. Cohen S, Hargreaves KM. Pathways of Pulp, 9th edn. St. Louis: Mosby; 2006.p.573.

2. Grossman L, Oliet S, Del Rio C. Endodontic Practice, 11th edn. Varghese Publication; 1991.pp.29-58. 3. Ingle J, Bakland L, Baumgartner J. Ingle’s Endodontics 6, 6th edn. BC Decker Inc, Hamilton; 2008.p.3.

CHAPTER

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The Dental Pulp and the Periradicular Tissues

This chapter describes the anatomy, embryology, histology and the physiology of the human dental pulp and its surrounding periradicular structures.   You must know • What is the Dental Pulp and the Dentin-Pulp Complex? • What are the Special Characteristics of the Dental Pulp as Connective Tissue? • How is the Dental Pulp Formed? • What are the Histologic Features of the Dental Pulp? • What is the Blood Supply of the Pulpal Tissues? • What is the Nerve Supply of the Pulpal Tissues? • What is the Lymph Supply of the Pulpal Tissues? • What are the Functions of the Dental Pulp? • What is the Morphology and Histology of the Periradicular Tissues?

WHAT IS THE DENTAL PULP AND THE DENTIN-PULP COMPLEX? Dental Pulp Dental Pulp is a soft vascular connective tissue of mesen­ chymal origin occupying the pulp chamber and the  root canals and provides dentinogenic, nutritive, sensory and defensive functions reflecting complete tooth vitality. A total of 52 pulp organs are usually present in human dentition, 32 in the permanent teeth and 20 in the primary teeth. Each pulp organ has the shape that conforms to that of the respective tooth. Each pulp organ is composed of: • Coronal pulp: Located centrally in the crowns of the teeth. • Radicular pulp: Located in the roots of the teeth. Coronal pulp resembles the shape of the outer surface of the crown dentin. Coronal pulp has six surfaces: the roof or occlusal, the mesial, the distal, the buccal, the lingual and the floor. The protrusions of the pulp that extend into

cusps of each crown are called pulp horns. The pulp organ constricts in the cervical region of the tooth and at this zone, the coronal pulp joins the radicular pulp. Radicular pulp extends from cervical region of crown to the root apex. Radicular portion of the pulp organ communicates with periapical connective tissues through the apical foramen or foramina. The anatomic components of the pulp cavity are discussed in detail in Chapter 3: “Morphology and Internal Anatomy of the Root Canal System”.

Dentin-Pulp Complex The specialized cells of the dental pulp, the odontoblasts, are arranged peripherally in direct contact with the dentin matrix. This close relationship between odontoblasts and dentin is referred to as the dentin-pulp complex. Dentin and pulp are embryologically, structurally and functionally related. Figure 2.1 shows the diagrammatic representation of histologic section of dentin-pulp complex. The histology of pulp is explained in detail later in this chapter.

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HOW IS THE DENTAL PULP FORMED? Development of Tooth

Fig. 2.1  Diagrammatic representation of histologic section of dentinpulp complex showing how dentin and pulp are structurally related

WHAT ARE THE SPECIAL CHARACTERISTICS OF THE DENTAL PULP AS CONNECTIVE TISSUE? Certain special characteristics of the pulp tissue that distinguish it from other connective tissues of the body are: • Dental pulp is encased within hard tissues in an unyielding low-compliance environment that limits its ability to increase in volume during episodes of vasodilation and increased tissue pressure. Pulp being incompressible, volume within pulp chamber cannot be increased. So, during an inflammatory reaction, there is an increase in tissue pressure instead of volume. • Even the mature pulp resembles embryonic connective tissue. Therefore, it is relatively rich source of stem cells. • Pulp is supported by microcirculatory system, its largest vascular components being arterioles and venules. There are no true arteries or veins that enter or leave the pulp. The pulp lacks a true collateral system and is dependent on relatively few arterioles entering through the foramina. Due to minimal collateral blood supply, there is reduced capacity for repair following injury. • After development of tooth also, the pulp retains its ability to form dentin throughout life. As a result, vital pulp can partially compensate for loss of enamel and dentin caused by mechanical trauma, disease or aging. • Sensory receptors in the pulp cannot differentiate between heat, touch, pressure or chemicals because pulp organs lack receptors specific to different stimuli. As a result, the unique feature of dentin receptors is that any of the environment stimuli always elicit pain as a response of the tooth.

The connective tissue cells underlying the oral ectoderm are neural crest or ectomesenchyme in origin and these cells induce or instruct the overlying ectoderm to start tooth development. Tooth development begins in the anterior portion of future maxilla and mandible and then proceeds posteriorly. During sixth week of embryonic life, certain areas of basal cells of oral ectoderm proliferate to form horseshoe shaped structures called the primary dental laminae associated with the maxillary and mandibular processes. Primary dental lamina splits into vestibular and dental lamina.

Role of Dental Lamina • It acts as primordium for ectodermal portion of deciduous teeth • Distal extension of dental lamina gives rise to permanent molars • Lingual extension of free end of dental lamina develops successors of deciduous teeth (Incisors, Canines and Premolars). The formative tissues for an entire tooth and its supporting structures include: • Enamel Organ (forms Enamel): It is downgrowth of dental lamina. • Dental Papilla (forms Dentin and Pulp): On inside depression of enamel organ, ectomesenchymal cells increase in number and tissue appears more dense representing dental papilla. • Dental Sac (forms Cementum and Periodontal ligament): It consists of ectomesenchymal cells and fibers that surround dental papilla and enamel organ. Stages of tooth development: Formation of tooth is a continuous process but for convenience and descriptive purposes, it is divided into various morphologic stages. The morphologic stages and the associated physiologic processes are as follows: Morphologic stage

Physiologic processes

Dental lamina

Initiation

Bud stage Cap stage Bell stage (Early) Bell stage (Advanced)

Proliferation Histodifferentiation Morphodifferentiation

Formation of enamel and dentin matrix

Apposition

The Dental Pulp and the Periradicular Tissues

Certain growth factors such as Epidermal Growth Factor (EGF) and others initiate tooth development ↓ Specific cells of dental lamina form Enamel organ in response to those factors

At the points of initiation, enhanced proliferative activity ensues and successively results into the different stages of tooth development. According to the shape of the epithelial part of tooth germ, they are called as Bud, Cap and Bell stages (Morphologic Stages): • Bud stage is the initial stage of tooth development during which the epithelial cells of dental lamina proliferate and produce a budlike projection into adjacent ectomesenchyme (Fig. 2.2). Differentiation of dental lamina ↓ Round or ovoid swellings arise from basement membrane at ten different points corresponding to future positions of deciduous teeth-primordia of enamel organs (the tooth buds)

Development of tooth germ is initiated and the cells continue to proliferate faster than the adjacent cells. Transition of the bud to the cap stage is important step in tooth morphogenesis that involves multiple signaling molecules within the enamel organ epithelium that regulate the expression of various transcription factors in the surrounding mesenchyme. • Cap stage is reached when the cells of dental lamina have proliferated to form a concavity with a caplike appearance (Fig. 2.3). It shows: – Outer Enamel Epithelium: Formed by outer cuboidal cells. – Inner Enamel Epithelium: Formed by elongated cells. – Stellate Reticulum: Branched reticular arrangement of cellular elements.

Fig. 2.2  Diagrammatic representation of bud stage

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– Cervical loop: Rim of enamel organ where outer and inner enamel epithelia join. – Enamel knot and cord: Cells in center of enamel organ are densely packed and form the enamel knot. Vertical extension of enamel knot into dental papillae is called Enamel cord. Enamel knot serves as a transient critical signaling center that has dense population of epithelial cells without any proliferative activity and marked by expression of multiple signaling molecules. These signaling molecules are critical for proper development of tooth organ. • Bell stage: As the cells forming the loop continue to proliferate, there is further invagination of the enamel organ into mesenchyme and the enamel organ assumes a bell shape (Figs 2.4 and 2.5).

Fig. 2.3  Diagrammatic representation of cap stage

Fig. 2.4  Diagrammatic representation of early bell stage

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Fig. 2.5  Diagrammatic representation of advanced bell stage

During bell stage, there is differentiation of inner enamel epithelium and enamel organ epithelial cells into ameloblasts and differentiation of mesenchymal cells into odontoblast and dentin production begins. Now the dental papilla is designated as dental pulp. It is during bell stage that crown assumes its final shape (Morphodifferentiation) and the cells that make hard tissue-ameloblasts and odontoblasts, acquire their distinctive phenotype (Histodifferentiation).

Histodifferentiation Undifferentiated mesenchymal cells of dental papilla

↓ Gradually differentiate Into stellate shaped fibroblasts

As the crown formation continues with the deposition of Enamel and Dentin, growth and organization of pulp vasculature occurs. During this time, unmyelinated sensory nerves and autonomic nerves develop into pulp tissue. Myelinated nerve fibers develop and mature at a slower rate. Advanced bell stage marks an important stage of Morphodifferentiation in the crown, that outlines the future Dentinoenamel junction. The boundary between outer enamel epithelium and the odontoblast forms future Dentinoenamel junction. The junction of inner and outer enamel epithelium at the basal margin of enamel organ represents the future Cementoenamel junction. Apposition is deposition of matrix of hard dental structures. Appositional growth of Enamel and Dentin is characterized by regular and rhythmic deposition of extracellular matrix with alternate periods of activity and rest at definite intervals.

Fig. 2.6  Diagrammatic representation of histologic section of the pulp showing predentin and zones of pulp

WHAT ARE THE HISTOLOGIC FEATURES OF DENTAL PULP? Dental pulp can be divided into four zones from the periphery to the center: 1. Odontoblastic zone 2. Cell-free zone of Weil 3. Cell-rich zone 4. Pulp proper

Odontoblastic Zone (Fig. 2.6) • This is the peripheral zone of the pulp that separates the loose connective tissue of the pulp from predentin. • Constituents: – Cell bodies of odontoblasts – Capillaries – Nerve fibers – Dendritic cells • Structure: – Odontoblasts have palisading arrangement, forming the periphery of the pulp. – There are tight and gap junctional complexes in between the odontoblast cell bodies, that connect them and bring about exchange of metabolites. – Odontoblasts in coronal pulp: - Have a crowded arrangement due to rapid reduction of pulp chamber due to dentin deposition.

The Dental Pulp and the Periradicular Tissues

- Odontoblasts are tall and columnar with the nuclei polarized towards the center of the pulp arranged in about 6–8 layers in the region of the pulp horns. • Odontoblasts in Radicular pulp: – Odontoblasts are cuboidal in midportion of radicular pulp – Have less crowded arrangement in root and spread out laterally – Odontoblasts are squamous or flattened in the apical portion of the pulp. Arranged in 2–3 layers in midportion of pulp and in a single layer in the apical pulp. • Function: Production and deposition of dentin is the primary function of odontoblasts.

Cell-Free Zone of Weil (Fig. 2.6) • This is a narrow zone about 40 um in width, located immediately subjacent to the odontoblastic zone. • Constituents: – Blood capillaries – Rich network of unmyelinated nerve fibers called as plexus of Rashkow – Slender cytoplasmic processes of fibroblasts – Ground substance. • Structure: Its presence or absence depends on functional status of pulp. It may be completely absent in young pulps during dentinogenesis and in older pulps due to reparative dentin formation. It is more prominent in coronal pulp. • Functions: – Capillaries are involved in the nutrition of odontoblasts especially during dentinogenesis and periods of inflammation – Rashkow’s plexus involved in the neural sensation of pulp – Ground substance involved in the metabolic exchanges of the cells and it has the role in limiting the spread of infection due to its consistency.

Cell-Rich Zone (Fig. 2.6) • Cell-rich zone is located central to the cell-free zone. • Constituents: – Ground substance – Fibroblasts – Collagen fibers – Undifferentiated mesenchymal cells – Macrophages.

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• Structure: Cell-rich zone is more prominent in coronal pulp than the radicular pulp. – Ground substance forms the matrix that surrounds and supports the cellular and vascular elements of pulp. It is composed of proteoglycans, glycoproteins and water. – Fibroblasts are present in large numbers in the cellrich zone especially in coronal portion. Fibroblasts are stellate-shaped cells with ovoid nuclei and cytoplasmic process. – Two types of fibers are found: i. Elastic fibers that are found in the walls of the arterioles. ii. Collagen fibers secreted by fibroblasts found in the body of the pulp. In young pulp, collagen fibers are small and occur in diffuse pattern and in older pulp, they are found in large bundles usually found in central region. The apical third of mature pulp contains more collagen fibers than the coronal third. – Undifferentiated mesenchymal cells are stellateshaped with a large nucleus and little cytoplasm. They are located around the blood vessels in the cell-rich zone. – Macrophages are blood monocytes that have migrated into the pulp tissue. • Functions: – Ground substance acts as a barrier against the spread of bacteria. It is a transport medium for metabolites and cellular waste products. – Fibroblasts bring about formation as well as degeneration of collagen fibers. They can bring about deposition of calcified tissue. They have the potential for reparative dentin formation. – Collagen fibers secreted by fibroblasts support the body of pulp and those secreted by odontoblasts form the dentinal matrix. Collagen fibers in the apical third of root protect the neurovascular bundle from injury. – Undifferentiated mesenchymal cells can differentiate into fibroblasts, odontoblasts, macrophages or osteoclasts to bring about repair and regeneration.

Pulp Proper • It forms the central mass of pulp. • Constituents: – Larger blood vessels – Nerve fibers – Fibroblasts

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– Undifferentiated mesenchymal cells – Defense cells: Macrophages, lymphocytes, dendritic cells – Ground substance. • Structure and Functions: Blood vessels and nerves are embedded in the pulp matrix in the central portion of pulp and send branches to the periphery of the pulp. Arterioles along with myelinated and unmyelinated sensory nerve fibers enter the pulp through the apical foramina and venules along with lymphatics exit the pulp through the apical foramina and lateral and accessory foramina.

Structural Elements of the Pulp The dental pulp contains: • Ground substance • Cells • Fibers • Blood vessels • Nerves • Lymph vessels.

Ground Substance • The Dental Pulp is a connective tissue that consists of cells and fibers, embedded in ground substance, also called Extracellular Matrix (ECM). ECM is amorphous and gel-like. • Contents: – Polyanionic polysaccharides – Glycoproteins such as fibronectin, laminin and tenascin – Proteoglycan such as hyaluronic acid, dermatan sulfate and chondroitin sulfate – Glycoprotein and proteoglycan contain GAG chains that bond to cell surfaces and – Other matrix molecules – Water content of young pulp is 90%. • Functions: – Forms a cushion that is capable of protecting cells and vascular component of the tooth – It acts as molecular sieve in which it excludes large proteins – Glycoprotein and proteoglycan molecules support cells, provide tissue turgor and mediate cell interactions – Proteoglycans regulate dispersion of interstitial matrix solutes, colloids and water and determine the physical characteristics of the pulp

– It serves as means for transport of nutrients from blood vessels to cells and transport of metabolites from cells to blood vessels. • In certain inflammatory lesions, degradation of ground substance can occur through the hydrolytic enzymes of lysosomal and bacterial origin.

Cells of the Pulp Odontoblast • Odontoblast is the most characteristic cell of the dentinpulp complex • It is responsible for dentinogenesis both during tooth development and even in the mature tooth • Odontoblast is a tall columnar cell and has a cellular process that forms dentinal tubule • Ultrastructure of odontoblast: Shows large nucleus, four nucleoli, well-developed Golgi complex, Golgi bodies centrally located, mitochondria, Rough Endoplasmic Reticulum (RER) and ribosomes distributed throughout the cell body • Odontoblast synthesizes type I collagen, proteoglycans, dentin sialoprotein and phosphophoryn. Phos­ phophoryn is phosphorylated phosphoprotein that is involved in extracellular mineralization and is found only in dentin, not in any other mesenchymal tissue • Odontoblast secretes acid phosphatase (a lysosomal enzyme) and alkaline phosphatase (enzyme related to mineralization).

Pulp Fibroblast • Most numerous cells of pulp • Fibroblast is a spindle-shaped cell responsible for collagen fiber formation throughout the pulp during the life of the tooth • Fibroblast synthesize type I collagen, type III collagen, proteoglycans and GAGs and maintain the matrix proteins of the ground substance. Fibroblasts are capable of ingesting and degrading this same matrix. Thus the fibroblasts have dual function of synthesis and degradation of the same cell • Fibroblasts remain in relatively undifferentiated state, never grow up. Undifferentiated cells are also termed as stem cells • Pericytes are fibroblasts found around capillaries of pulp.

Defense Cells • Histiocytes or Macrophages: They are active in endo­ cytosis and phagocytosis and act as scavengers that

The Dental Pulp and the Periradicular Tissues

remove extravasated red blood cells, dead cells and foreign bodies from the tissue. Few macrophages are involved in immune reactions by processing antigen and presenting it to the memory T cells. • Dendritic cells: They are the accessory cells of the immune system and are termed as antigen presenting cells. They induce T-cell dependent immunity. • Lymphocytes: T-lymphocytes are mainly found. B-lymphocytes are scarce. Lymphocytes appear at the site of injury after invasion by Neutrophils (PMN Leukocytes) • Mast cells: They are found in relation to blood vessels in chronically inflamed pulps. Mast cell granules contain heparin (anticoagulant) and histamine (inflammatory mediator) and other chemical factors.

Undifferentiated Mesenchymal Cells • They are the primary cells in very young pulp, but a few undifferentiated cells remain in the pulps after root development. Their number decreases in older pulps. • They are believed to be totipotent cells that can differentiate into odontoblasts, fibroblasts or macro­ phages when need arises. Also called Reserve cells. • These cells are found scattered throughout the central pulp along pulp vessels in cell-rich zone. • They appear polyhedral in shape with peripheral processes and large oval staining nucleus.

Fibers

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Arterioles, Venules and Capillaries and Arteriovenous Anastomoses • Blood from the arteries enters the tooth by way of Arterioles having diameter of 100 µm or less and the Venules having diameter of 200–300 µm leave the tooth through the apical foramen. Smaller vessels may enter the pulp via accessory or lateral canals. But the tooth does not have a collateral alternative blood supply. • From the root pulp, arterioles pass to supply the coronal pulp in a straight direction so that 90o branching patterns develop as shown in Figure 2.7. – They spread laterally towards the odontoblast layer and form a capillary plexus beneath the odontoblast layer. – Terminal capillary networks are most important vessels in the pulp and carry out the following functions: Maintains pulp homeostasis by: a. Transport of nutrients and gas to cells b. Removal of waste products and CO2 from the cells. • Coronal portion of the pulp has nearly twice the capillary blood flow than the root portion being greatest in the region of Pulp Horns. • From the capillary networks, blood passes into postcapillary venules and into larger venules. These venules have thin and discontinuous muscular coat for the movement of fluid in or out of the vessel. • Arteriovenous anastomosis connects the arteriole directly to a venule bypassing the capillary bed. These are small vessels having diameter of 10 µm. They may

• The pulp consists of Type I and Type III collagen fibers • Odontoblasts and osteoblasts synthesize Type I collagen; Fibroblasts synthesize Type I, III, V and VII collagen • After completion of root formation, the pulp matures and collagen fiber bundles increase in number. Thus, the collagen content of pulp increase with age.

WHAT IS THE BLOOD SUPPLY OF THE PULPAL TISSUES? Arterial Supply • Arterial supply of the pulp is from the posterior superior alveolar arteries and – Infraorbital artery – Inferior alveolar branch of internal maxillary arteries.

Fig. 2.7  Diagrammatic representation of pulpal blood supply

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play a role in regulation of blood flow. May be found in coronal and radicular portions of pulp, more frequent in radicular portion. ‘U’-Turn loops filled with streaming blood may be found in the pulp vascular network that shunt blood away from area of injury or inflammation thus preventing injury to microcirculation. Changes in pulpal blood flow can be measured using the laser Doppler flowmeter. Pulpal blood flow may be affected by change in posture. Change of posture from standing to supine position causes increase in blood flow resulting in elevated pulpal tissue pressure sufficient to activate pulpal nocireceptors to initiate spontaneous pulpal pain. The stealing theory of pulpal blood flow: Most of the vascular resistance regulating the pulpal blood flow is located in the venules and also outside the pulp. As a result, Changes in blood flow in surrounding tissues such as gingiva, alveolar bone and PDL ↓ Causes changes in pulpal blood flow

in close association with the blood vessels of the pulp and many are sympathetic in nature. A-fibers transmit fast pain which is sharp and piercing. C-fibers transmit slow pain which is dull, aching pain. • Apart from sensory fibers, sympathetic fibers from the superior cervical ganglion appear with the blood vessels when the vascular system is established in the dental papilla. In adult tooth, sympathetic fibers form plexuses around the pulpal arterioles usually. • A network of nerves located adjacent to the cell-rich zone formed by peripheral axons is called plexus of Raschkow. A-delta fibers lose their myelin sheath at the odontoblastic layer forming this plexus. Formation: Nerve bundles along with the blood vessels pass from radicular pulp to coronal pulp ↓ They branch into smaller bundles beneath the cell-rich zone ↓ Ramify into plexus of single-nerve axons called the plexus of Raschkow ↓ In this plexus, A-fibers emerge from their myelin sheaths and branch further to form sub-odontoblastic plexus within the Schwann cells from which terminal axons exit and pass between odontoblasts as free nerve endings.

• Dental pulp is called as the LOW COMPLIANCE SYSTEM because it is encased in rigid structures namely enamel, dentin and cementum. Due to limited ability of pulp to expand, any vasodilatation and increased vascular permeability occurring during inflammation cause an increase in pulpal hydrostatic pressure and thus reduced pulpal blood flow. A mind-map to remember all points of blood supply of pulpal tissues (Fig. 2.8).

• Pain sensation caused by external stimuli in the tooth is mediated by large myelinated fibers. • Certain neurotransmitters are present in the nerves of the dental pulp such as substance P, 5-Hydroxytryptamine, Vasoactive Intestinal peptide, prostaglandins, acetyl­ choline, norepinephrine. • Sensory response in the pulp cannot differentiate between heat, touch, pressure or chemicals because pulp organs lack receptors specific to different stimuli. As a result, the unique feature of dentin receptors is that environmental stimuli always elicit pain as a response. • A-delta fibers get stimulated first when Electric pulp tester is used. C-fibers also get stimulated if intensity of stimulus is increased. A mind-map to remember all points of Nerve supply of pulp is given in Figure 2.9.

WHAT IS THE NERVE SUPPLY OF PULPAL TISSUES?

WHAT IS THE LYMPH SUPPLY OF PULPAL TISSUES?

• Trigeminal ganglion supplies sensory innervation to pulp by means of: – Maxillary nerve and – Mandibular nerve • Within the dental pulp, two types of sensory nerve fibers: – Myelinated A-fibers including A-β and A-d (90% are Ad) – Unmyelinated C-fibers: About 80% of nerve fibers that enter the pulp are Unmyelinated. They are found

Lymphatic vessels help to remove the interstitial fluid and metabolic waste products and maintain the tissue pressure within the pulp. Most of the lymphatics are found in the radicular pulp whereas in coronal pulp, lymph vessels are observed in central part. Lymphatics in peripheral pulp join to form large collecting vessels, which further unite with progressively larger lymphatic vessels that pass through the root apex along with blood vessels.

According to Poiseuille law, “Any vasodilatation in tissues that receive their blood supply through the side branches of the end arterioles feeding the pulp will, steal blood pressure from the pulp.” Thus, vasodilatation of alveolar bone, periodontal ligament or gingiva ↓ Fall in arterial blood pressure of the arterioles feeding the pulp

The Dental Pulp and the Periradicular Tissues

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Fig. 2.8  A mind-map to remember all points of blood supply of pulpal tissues

Lymph vessels draining the pulp and the periodontal ligament of anterior teeth pass to the submental lymph nodes and those of the posterior teeth pass to the submandibular and deep cervical lymph nodes.

WHAT ARE THE FUNCTIONS OF THE PULP? • Inductive: The pulp anlage interacts: – With the oral epithelial cells leading to differentiation of the dental lamina and enamel organ formation.

– With the developing enamel organ to determine the particular type of tooth. • Formative: The cells of the pulp organ produce the dentin that surrounds and protects the pulp. The pulpal odontoblasts play a role in developing the organic matrix and calcification during dentin formation. • Nutritive: The blood vascular system of the pulp nourishes the surrounding avascular dentin through odontoblasts and their processes.

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Fig. 2.9  Mind-map to remember nerve supply of pulp

•

•

Sensory: Although the pulp is encased by protective layer of dentin, which in turn is covered with enamel, the pulp is quite sensitive to different external stimuli such as heat, cold, pressure, chemicals and mechanical trauma. The response is always pain irrespective of the type of stimulus due to lack of specific receptors related to those stimuli. The nerves in the pulp initiate reflexes that control circulation in the pulp. Defensive or reparative: The dental pulp responds to mechanical, thermal, chemical or bacterial irritation by producing reparative dentin and mineralizing any affected dentinal tubules (Sclerosis) to wall off the pulp from the source of irritation. In response to bacterial infection, pulp elicits inflammatory and immunologic reaction. The macrophages, lymphocytes, neutrophils, monocytes, plasma and mast cells of the pulp help in the process of repair of the pulp. A mind-map listing all points of dental pulp is given in Figure 2.10.

WHAT IS THE MORPHOLOGY AND HISTOLOGY OF PERIRADICULAR TISSUES? Periradicular tissues include (Fig. 2.11): • Cementum • Periodontal ligament • Alveolar process

Cementum Cementum is hard, bone-like calcified tissue structure covering the roots of the teeth.

Types • •

Cellular cementum Acellular cementum.

Cellular Cementum • It contains cells called cementocytes and deposited usually in the apical third of root.

The Dental Pulp and the Periradicular Tissues

Fig. 2.10  Mind-map to remember all points of the dental pulp

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• Due to its avascularity, cementum can withstand the orthodontic tooth movement forces without much resorptive damage. • To maintain width of PDL space by continuous deposition of cementum.

Periodontal Ligament The periodontal ligament is a dense, fibrous connective tissue surrounding the roots of the teeth and occupying the space between the cementum and the alveolar bone and is continuous with the pulp and the gingiva. It attaches the root to the surrounding tissues. Two important components of periodontal ligament are: 1. Cells 2. Fibers Fig. 2.11  Diagram showing periradicular tissues

Cells of PDL • It is deposited at a greater rate than acellular cementum • Thickness: 20 to 150 µm. Acellular Cementum • It does not contain cells and deposited in the cervical and middle thirds of root • Thickness is 20–50 µm at CEJ • It contains lot of Sharpey’s fibers.

Functions • To give form to the mature apical foramen. Continuous deposition of cementum increases the major diameter and deviates the apical foramen by about  0.2 to 0.5mm from the center of the root apex. The minor diameter is located about 0.5mm from the cemental surface in young teeth and about 0.75mm from the cemental surface in mature teeth. • Cementum plays a role in repair. Root resorptions get repaired by deposition of cementum. Accessory and apical foramina are sealed after root canal treatment due to deposition of cementum. • To form apical barrier in immature pulpless teeth Materials used for apexification bring about deposition of cementum or cementum-like tissue to close the apex of immature pulpless teeth.

Fibroblasts • Most important cells of the periodontal ligament • Bring about deposition as well as degradation of collagen fibers. This constant remodelling of periapical fibers maintains the health of the periodontal ligament. Osteoblasts (Bone Forming Cells) • Bring about deposition of collagen and matrix on the surface of the bone forming the osteoid • Calcification of osteoid occurs to anchor Sharpey’s fibers. Osteoclasts (Bone-resorbing Cells) • These are multinucleated Giant cells found in scooped out areas of bone called Howship’s lacunae. • They bring about resorption of bone. The constant remodelling of bone by deposition and resorption continuously renews the attachment of PDL to bone. Cementoblasts • Bring about deposition of matrix containing collagen fibers and ground substance called cementoid. • Calcification of cementoid occurs to anchor the periodontal ligament fibers in the bone.

The Dental Pulp and the Periradicular Tissues

Cementoclasts • Under physiologic conditions, there is no resorption of cementum. So cementoclasts are not found in the normal periodontal ligament. • Found in pathologic conditions. Other Cells • Epithelial cell rests of Malassez • Undifferentiated mesenchymal cells • Mast cells • Macrophages.

Fibers of PDL • Two types of periodontal fibers are present: – Collagen fibers – Oxytalan fibers • Sharpey’s fibers are terminal fibers of the collagen bundles that are: – Inserted into CEMENTUM on one side – Inserted into BONE on the other side. • The principal fiber groups of periodontal ligament include: – Transseptal fibers: Traversing the alveolar crest and connecting from cementum of one tooth to the cementum of adjacent tooth. – Horizontal group of fibers: Embedded into cementum apical to the alveolar crest group running horizontally from cementum to the alveolar bone. – Oblique group of fibers: Embedded into cementum apical to horizontal group running obliquely from cementum to the alveolar crest of bone. – Alveolar crest fibers: They arise from the alveolar crest of the bone in a fan-like manner and attach to the cementum. – Apical group of fibers: These fibers are embedded into the apical cementum and the fundus of the alveolar socket. – Interradicular group of fibers: Embedded into cementum and alveolar bone in the furcation areas of Multirooted teeth. Oxytalan fibers are immature elastic fibers that traverse the periodontal ligament in an axial direction. • Functions of the periodontal ligament: – Attachment: The fibers of the periodontal ligament attach the tooth to the alveolar bone (socket). – Protection: The fibers absorb the occlusal forces and protect the tooth and the alveolar socket from the masticatory injuries.

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– Nutrition: The periodontal ligament provides blood supply to the adjoining structures such as gingiva, cementum and alveolar bone. – Formation: The cells of the PDL help in the formation of adjoining structures such as alveolar bone and cementum.

Alveolar Process It can be divided into: • Alveolar bone proper which is a part of periradicular tissues • Supporting alveolar bone.

Alveolar Bone Proper • Alveolar bone proper is the bone forming the bony socket into which the root is housed. • Alveolar bone proper consists of: – Peripheral bone called bundle bone into which the Sharpey’s fibers of the PDL are embedded. – Central bone called lamellated bone. • Alveolar bone proper appears radiopaque on radiographs and is called as lamina dura. • Alveolar bone proper consists of multiple foramina containing blood vessels and nerve fibers that supply the teeth, periodontal ligament and alveolar bone. So, it is also known as the cribriform plate.

Supporting Alveolar Bone • It is formed by diploe of cancellous bone covered by two outer tables of cortical bone: – Vestibular or buccal plate – Lingual or palatal plate. • Cancellous bone is arranged in the form of trabeculae and there are medullary spaces in between the trabeculae. • Cells of the alveolar bone: – Osteoblasts are bone-forming cells, which deposit an organic matrix called osteoid which then gets calcified. – Osteocytes are the cells which get entrapped in the organic matrix. – Osteoclasts are bone-resorbing cells. A mind-map to remember all points of Periradicular tissues is given in Figure 2.12.

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Fig. 2.12  A mind-map to remember all points of periradicular tissues

BIBLIOGRAPHY 1. Bhaskar SN. Orban’s Oral Histology and Embryology, 11th edn. Mosby, 2001.pp.28-48,pp.139-79. 2. Cohen S, Hargreaves KM. Pathways of Pulp, 9th edn. St.  Louis: Mosby, 2006.pp.460-513.

3. Grossman L, Oliet S, Del Rio C. Endodontic Practice, 11th edn. Varghese Publication; 1991.pp.29-58. 4. Ingle J, Bakland L, Baumgartner J. Ingle’s Endodontics 6, 6th edn. BC Decker Inc, Hamilton; 2008.pp.118-50.

CHAPTER

3

Morphology and Internal Anatomy of the Root Canal System

This chapter describes the morphology and internal anatomy of teeth and their root canal systems   You must know • What are the Anatomic Components of the Root Canal System? • What are the Regressive Changes that Occur in the Anatomy of Root Canal System? • What are the Different Types of Root Canal Systems in any Root? • What is the Anatomy of the Apical Portion (Apical 1/3rd) of the Root Canal? • Which are the Anatomic Complexities that can Occur in Root Canal System? • What is Isthmus and what is its Role during Endodontic Surgical Procedure? • What are the Possible Developmental Anomalies and Variations in the Anatomy of Root Canal System? • What is the Morphology of the Root Canal System of the Individual Teeth?

WHAT ARE THE ANATOMIC COMPONENTS OF THE ROOT CANAL SYSTEM? Central cavity within a tooth that is entirely enclosed by dentin except at the apical foramen, into which the pulp is housed is called as the root canal system. Root canal system can be divided into two basic components: 1. Pulp chamber: Coronal portion, that which is located in anatomic crown of tooth. Also called coronal pulp. 2. Root canal: Radicular portion, that which is located in anatomic root of tooth. Also called radicular pulp.

Components of the Pulp Chamber (Fig. 3.1) • Roof of the pulp chamber: Portion of dentin covering the pulp chamber occlusally or incisally is called as the roof of the pulp chamber. • Pulp horn: An accentuation of the roof of the pulp chamber directly under a cusp or developmental lobe is called as the pulp horn. • Floor of the pulp chamber: The portion of dentin bounding the pulp chamber near the cervix of the tooth

particularly that forming the furcation area is called as the floor of the pulp chamber. It runs parallel to the roof of the pulp chamber. • Walls and angles of the pulp chamber: Walls of the pulp chamber correspond to the respective walls of the tooth  surface. Angles of the pulp chamber correspond to the respective angles formed from the walls of the pulp chamber.

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• Canal orifices: The openings in the floor of the pulp chamber that lead into the root canals are called as the canal orifices. They are not separate structures, but are continuous with both pulp chamber and root canals.

Components of the Root Canal (Fig. 3.1) • Principal/main root canal: – The root canal is that portion of the pulp cavity from the canal orifice to the apical foramen. – For convenience, the root canal is divided into three sections namely: coronal, middle and apical thirds. – Usually the root canal does not extend straight along the entire length of the root. Either a curvature or a constriction is present before the apex is reached. – The shape of the root canal usually conforms to the shape of the root. If there is curvature in the root, usually the root canal follows this curve. – The curvature may be: a. Gradual curvature of the entire canal. b. Sharp curvature of canal near the apex. c. Gradual curvature of canal with straight apical ending. d. Double curvature of the canal (S-shaped canal). – Usually, the number of root canals corresponds to the number of roots. But a root can have more than one canal. For example, the mesial root of

•

•





• •

• Fig. 3.1  Diagram showing components of root canal system. A: Coronal pulp; B: Radicular pulp/Principal root canal; a: Pulp horn; b: Roof of pulp chamber; c: Canal orifice; d: Floor of pulp chamber; e: Lateral canal; f, g, h: Portals of Exit (POE)

mandibular first molar almost always has two canals; its distal root occasionally has two canals. – According to Meyer, roots which are round and cone-shaped, usually contain only one canal but roots which are elliptical and have flat or concave surfaces frequently have more than one canal. Apical foramen: A funnel-shaped opening where the root canal exits is called as the apical foramen. Besides there are numerous geometrical configurations and intricacies along the length of the root canal. Apical foramen may be located in the center of root apex or may exit on the mesial, distal, labial or lingual surface of the root slightly eccentrically. Accessory, lateral and furcation canals: Minute canals extending in horizontal, vertical or lateral directions from pulp to the periodontium are called as accessory canals. Accessory canals consist of connective tissue and vessels but they do not supply the pulp with collateral circulation. Accessory canals that branch to the lateral surface of the root are called as lateral canals. These may be visible on radiograph. Canals occurring in the bifurcation or trifurcation of multirooted teeth are called as the furcation canals. Formation: Accessory canals are formed as a result of entrapment of periodontal vessels in Hertwig’s Epithelial Root Sheath (HERS) during calcification. Furcation canals are formed as a result of entrapment of periodontal vessels during the fusion of diaphragm that becomes pulp chamber floor. Clinical significance: Accessory, lateral and furcation canals can serve as avenues for the passage of irritants, primarily from the pulp to the periodontium. Accessory foramina: Openings of accessory and lateral canals in root surface are called as accessory foramina. Apical delta: A pyramidal or pointed structure made of multiple fine channels in the apical third of the root through which the blood vessels and nerves pass is called apical delta. Figure 3.2 shows the diagrammatic representation of the apical delta. For convenience, the root canal is divided into three sections: coronal, middle and apical thirds as shown in Figure 3.1. Portals of exit (POE): The openings from the root canal system to the PDL space through which the microorganisms and the potential Endodontic breakdown products may pass are referred to as Portals of Exit (POE).

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Fig. 3.2  Diagrammatic representation of the apical delta

Fig. 3.3  Characteristics of root canal system in young person

WHAT ARE THE REGRESSIVE CHANGES THAT OCCUR IN THE ANATOMY OF ROOT CANAL SYSTEM? See Figures 3.3 to 3.5.

Fig. 3.4  Characteristics of root canal system with increasing age

WHAT ARE THE DIFFERENT TYPES OF ROOT CANAL SYSTEMS IN ANY ROOT? The canals within the root, may branch, divide and rejoin.

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A

C

B

D

Figs 3.5A to D  Diagrams showing age changes in the root canal system in order: a: Pulp horns: High pulp horns go on receding with increasing age; b: Pulp chamber: Large and wide pulp chambers become smaller and shorter; c: Root canals: Wider root canals become narrower due to deposition of secondary and reparative dentin; d: Apical foramen: Broad open apex of immature tooth closes and becomes narrow and forms an apical stop; e: Pulp stones: Calcification is seen in older pulps and few pulps with chronic infection. Calcification starts in the pulp chamber and proceeds apically

Classification of Root Canal Systems (Fig. 3.6) The possible configurations of the root canal systems as given by Weine include: • Type I: Single canal extending from the pulp chamber to the apex (1) (Fig. 3.6A) • Type II: Two separate canals leaving the pulp chamber and joining short of the apex, to form one canal (2-1) (Fig. 3.6B) • Type III: Two separate, distinct canals extending from the pulp chamber to the apex (2) (Fig. 3.6C)

• Type IV: One canal leaving the pulp chamber and dividing short of the apex into two separate, distinct canals with separate apical foramina (1-2) (Fig. 3.6D) Weine’s classification is the first clinical classification of more than one canal system in a single root. Later, Vertucci et al gave the classification categorizing the root canal system into following eight types: 1. Type I: Single canal extending from the pulp chamber to the apex (1) (Fig. 3.7) 2. Type II: Two separate canals leaving the pulp chamber and joining short of the apex, to form one canal (2-1) (Fig.  3.8)

Morphology and Internal Anatomy of the Root Canal System

A

B

C

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D

Figs 3.6A to D  Weine’s classification of root canal systems

Fig. 3.7  Type I

Fig. 3.8  Type II

3. Type III: One canal leaving the pulp chamber and dividing into two canals in the root. The two root canals then merge to exit as one canal (1-2-1) (Fig. 3.9) 4. Type IV: Two separate, distinct canals extending from the pulp chamber to the apex (2) (Fig. 3.10) 5. Type V: One canal leaving the pulp chamber and dividing short of the apex into two separate, distinct canals with separate apical foramina (1-2) (Fig. 3.11) 6. Type VI: Two separate canals leaving the pulp chamber, and joining in the body of the root to form one canal, which redivides short of the apex to exit as two distinct canals (2-1-2) (Fig. 3.12).

7. Type VII: One canal leaving the pulp chamber and dividing into  two canals and then rejoining to form one canal in the body of the root, and then finally redivides into two distinct canals short of the apex (1-2-1-2) (Fig. 3.13). 8. Type VIII: Three separate, distinct canals extending from the pulp chamber to the apex (3) (Fig. 3.14). The only tooth that has been found with all eight possible configurations is the maxillary 2nd premolar. According to Vertucci’s classification: • Types I, II, III show One canal at apex

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Fig. 3.9  Type III

Fig. 3.12  Type VI

Fig. 3.10  Type IV

Fig. 3.13  Type VII

Fig. 3.11  Type V

Fig. 3.14  Type VIII

Morphology and Internal Anatomy of the Root Canal System

• Types IV, V, VI, VII show Two canals at apex • Type VIII shows Three canals at apex.

Vertucci’s Findings • Whether the canals join or remain as separate canals, is determined by the proximity of the canal orifices. • Joining of canals: If orifices are less than 3 mm apart, canals usually are joined together. As the distance between the orifices decreases, canals are found to join more coronally. • Separation of canals: If the distance between the orifices is more than 3 mm, the canals tend to remain separate through their entire length.

Some of the Practical Hints to Determine the Type of Canal System Clinically • It is important to have knowledge of different variations that can occur in the root canal anatomy including the possibility of finding additional canals than the usual for a given tooth. • Pretreatment radiographs taken in two-three different angulations gives an idea of the internal anatomy of the tooth and the number of root canals. • Follow the “dentinal map” which is the road-map to the root canal system and preserve the pulpal floor. • Location of canal orifice on pulpal floor can indicate the number of canals present as follows: – Canal located in center of the pulpal floor may indicate that one canal is present. – Canal orifices located less than 3 mm apart: Indicates tendency to join/unite. – Canal orifices located more than 3 mm apart may indicate tendency to remain separate. • On radiograph, sudden disappearance or narrowing of canal (fast-break guideline): Indicates bifurcation of root canal. • When the first file inserted into distal canal of a mandibular molar, points in buccal or lingual direction: may indicate 2 distal canals are present. • When two canals join in the root to form one canal, lingual/palatal canal has direct access to apex. • When one canal separates into two canals, configuration of separated canals is in the shape of letter ‘h’, where (given by Slowey) – Buccal canal is straight portion of ‘h’ – Lingual canal generally is the one that splits from the main canal at a sharp angle. • Krasner and Rankow have given certain guidelines or laws of pulp chamber anatomy to help clinicians

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determine the number and location of orifices on the pulp chamber floor which have been described in detail in Chapter 13: Endodontic Access Cavity Preparation. Those guidelines should be followed. • Magnification and illumination aids such as dental loupes and dental operating microscope are valuable aids that improve visualization and greatly reduce the chances of missing root canals or any variable anatomy. • Other orifice location aids such as Champagne bubble test using sodium hypochlorite and other aids have been described in Chapter 13: Endodontic Access Cavity Preparation.

WHAT IS THE ANATOMY OF THE APICAL PORTION (APICAL 1/3rd) OF THE ROOT CANAL? The apical portion of the root contains three anatomic and histologic landmarks (Fig. 3.15): I. Apical foramen or major apical diameter. II. Apical constriction or minor apical diameter. III. Cementodentinal junction (CDJ).

Apical Foramen or Major Apical Diameter (Fig. 3.15b) • Cohen has defined it as follows: “Apical foramen is the circumference or rounded edge, like a funnel or crater, that differentiates the termination

Fig. 3.15  Diagrammatic representation of anatomy of apical third of root. a: Cementum; b: Apical foramen; c: Cementodentinal junction (CDJ); d: Major constriction; e: Minor constriction; f: Apical constriction

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of the cemental canal from the exterior surface of the root”. Generally, the apical foramen does not exit at the apex, it may be about 0.5 – 3 mm offset from center. The apical foramen may not always be located in the center of the root apex and it may be on mesial, distal, labial or lingual surface of the root. In immature tooth with open apex, the apical foramen is funnel-shaped filled with periodontal tissue which is replaced by dentin and cementum as the root develops so that the apical foramen becomes narrower. Root canals can take various courses and accordingly the apical foramen is located. Figures 3.16A to D show different curvatures of root canals and the locations of the apical foramina. Average size of apical foramen in maxillary permanent teeth is 0.4 mm diameter and that of mandibular permanent teeth is 0.3 mm. The apical opening may not always be found in the center of the apex. Frequently two or more foramina are found separated by a portion of dentin and cementum or by cementum only.

Apical Constriction or Minor Apical Diameter (Fig. 3.15f) • Apical constriction is the part of the root canal with the smallest diameter. • Apical constriction is generally 0.5 – 1.5 mm inside the apical foramen. • Apical constriction is delicate and should be maintained. Over-instrumentation violates and breaks this constriction resulting in irritation of periapical tissues and over-extended root canal filling may occur. • The mean distance between the major and minor apical diameters, i.e. between the AF and AC has been found

A

B

C

D

Figs 3.16A to D  Various courses of the root canals and the location of the apical foramina: (A) Curvature in the apical third of the root canal and apical foramen distant from the root apex; (B) Curvature in the apical third of the root canal and apical foramen near the apex; (C)  Constriction in the root canal as the apical foramen is approached; (D) Double curvature of the root canal and apical foramen distant from root apex

to be 0.5 mm in young persons and 0.67 mm in older individuals. • The space that occurs between the major and minor apical diameters, i.e. between the AF and AC is funnel shaped, described as ‘hyperbolic’ shape or ‘shape of the morning-glory’.

Cementodentinal Junction (CDJ) (Fig. 3.15c) • • • •

It is the junction where cementum meets dentin. At CDJ, pulp tissue ends and periodontal tissues begin. CDJ is approximately 1 mm from the apical foramen. The CDJ is considered to be the ideal point of termination for the preparation and obturation of the root canals.

Anatomy of Root Apex Figure 3.15 shows diagrammatic representation of anatomy of root apex. A mind-map to remember all points of landmarks in apical portion of canal is illustrated in Figure 3.17.

WHICH ARE THE ANATOMIC COMPLEXITIES THAT CAN OCCUR IN ROOT CANAL SYSTEM? Anatomic complexities of root canal system include: • C-shaped canals • Additional canals • Fins, deltas, loops, intercanal connections, etc.

‘C’-shaped Canals (Fig. 3.18) • Roots and their root canals with their cross-sectional morphology C-shaped are called as C-shaped canals. • C-shaped canal first documented in Endodontic literature by Cooke and Cox in 1979. • C-shaped canals result from fusion of the mesial and distal roots on either the buccal or the lingual root surface. Failure of fusion of the Hertwig’s epithelial root sheath to fuse on buccal or lingual root surface forms C-shaped roots that contain C-shaped canals. • Occurs most commonly in mandibular second molars but may also be seen in mandibular first molar, maxillary first and second molars. • C-shaped root canal system has single, ribbon-shaped orifice that has an arc of 180 degrees or more. • It starts at mesiolingual line angle of pulp chamber and goes around buccal or lingual and ends at distal aspect of pulp chamber. • Classification of C-shaped canals: I. Based on number of canals that leave from orifice and reach apex (Flow chart 3.1)

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Fig. 3.17  A mind-map to remember all points of landmarks in apical portion of canal Flow chart 3.1  Classification of C-shaped canals based on number of canals that leave orifice and reach apex

Flow chart 3.2  Melton’s classification of C-shaped canals

Fig. 3.18  C-shaped canal in mandibular second molar

II. Classification of C-shaped canals as given by Melton et al (based on their cross-sectional shape) (Flow chart 3.2)

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Short Textbook of Endodontics Flow chart 3.3A  Fan et al’s anatomic classification of C-shaped canals

Flow chart 3.3B  Fan et al’s radiographic classification of C-shaped canals

Fig. 3.19  Diagrammatic representation of anatomic classification of C-shaped canals: Category I, II, III, IV, V

III. Fan et al classification of C-shaped canals: In 2004, Fan et al modified the Melton’s classification and gave two classifications: anatomic and radiographic (Flow chart 3.3) a. Anatomic classification: (Flow chart 3.3A) Figure 3.19 shows cross-section at the apical 1/3rd of the root of mandibular second molar showing different categories of C-shaped canals. b. Radiographic classification: (Flow chart 3.3B) Figure 3.20 shows Type I, Type II and Type III C-shaped canals respectively as per radiographic classification.

Fig. 3.20  Type I, Type II, Type III of C-shaped canals (Radiographic classification)

Morphology and Internal Anatomy of the Root Canal System

• Sometimes the C-shaped groove runs connecting two or three orifices such as mesiobuccal and distal orifices or mesiobuccal and distobuccal and distolingual orifices with the mesiolingual orifice remaining separate in mandibular first molar. These canals at the apical portion may end into separate apical foramina or may get merged to exit as single canal. Due to a number of anatomic variations seen in the C-shaped canal morphology, the cleaning, shaping and obturation of these teeth becomes difficult. Figures 3.21A and B show preoperative and postoperative radiographs of mandibular second molar with C-shaped canal. • Presence of additional canals: There is always a possibility of additional root canals than that are normally found, in any tooth. If these canals are missed, it results in incomplete debridement causing Endodontic failure.

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• Other complexities: Fins, deltas, loops, intercanal connections, etc.

WHAT IS ISTHMUS AND WHAT IS ITS ROLE DURING ENDODONTIC SURGICAL PROCEDURE? When two or more canals are present in the root, a narrow ribbon-shaped communication that occurs between the root canals containing pulp or pulpally derived tissues is called an isthmus (Fig. 3.22A). Kim et al classified isthmi into 5 types that can be found: 1. Type I: An incomplete isthmus with a faint communication between the two canals (Fig. 3.22B). 2. Type II: A complete isthmus with a definite communication between the two canals (Fig. 3.22C). 3. Type III: A very short, complete isthmus between the two canals (Fig. 3.22D). 4. Type IV: A complete or an incomplete isthmus that occurs between three or more canals (Fig. 3.22E). 5. Type V: Two or three canal openings without visible communication between the canals (Fig. 3.22F).

ROLE OF ISTHMI IN ENDODONTIC SURGICAL PROCEDURE

A

• When multiple canals are present, careful inspection of the resected root surface is to be done to locate all isthmi. • Although the canals may be thoroughly cleaned, the narrow isthmus area remains untouched. Thus it serves as bacterial reservoirs. So, all isthmi must be identified, prepared and filled with appropriate root end filling material for the success of surgical procedure.

WHAT ARE THE POSSIBLE DEVELOPMENTAL ANOMALIES AND VARIATIONS IN THE ANATOMY OF ROOT CANAL SYSTEM?

B Figs 3.21A and B  Preoperative and postoperative radiographs of mandi­bular second molar with C-shaped canal (Courtesy of Dr Nilesh Kadam)

Certain developmental anomalies cause variations in root canal anatomy that may render the execution of Endodontic procedures difficult or even impossible sometimes. • Hypopitutarism: In this condition, there is retarded eruption of teeth and open root apices may be seen. • Hyperparathyroidism: Pulp calcification and loss of lamina dura may be seen. • Gemination: It is a developmental anomaly characterized by two completely or incompletely separated crowns that have single root and root canal caused by division of single tooth germ by invagination (Fig. 3.23).

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A

B

C

D

E

F

Figs 3.22A to F  (A) Diagram showing enlarged view of ribbon-shaped communication between root canals: Isthmus; (B) Type I; (C) Type II; (D) Type III; (E) Type IV; (F) Type V

Fig. 3.23  Diagrammatic representation of gemination

Fig. 3.24  Diagrammatic representation of fusion of teeth

• Fusion: It is a developmental anomaly caused by union of two normally separated tooth germs. The tooth may have separate or fused root canals (Figs 3.24 and 3.25). • Concresence : It is the fusion of teeth after root formation is completed. Teeth are joined by cementum only (Fig. 3.26).

• Dilaceration: It is an angulation or a sharp bend or curve in the root or crown of a formed tooth caused due to trauma during tooth development. This curvature needs to be recognized on preoperative radiograph to prevent procedural errors (Fig. 3.27). • Talon’s cusp: It is an anomalous structure that resembles an eagle’s talon, that projects lingually from the

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Fig. 3.25  Intraoral periapical radiograph showing fusion of lower central and lateral incisor teeth of both left and right sides appearing as wide central teeth having fused pulp chambers and root canals (Courtesy of Dr Mansi Shah, Dentoview-Advanced Dental Imaging Center)

Fig. 3.27  Diagrammatic representation of dilaceration in the apical third of the roots of a maxillary molar

Fig. 3.26  Diagrammatic representation of concresence of maxillary second and third molars

Fig. 3.28  Intraoral periapical radiograph showing dens in dente in maxillary left central incisor (Courtesy of Dr Mansi Shah, Dentoview Advanced Dental Imaging Center)

cingulum area of maxillary or mandibular permanent incisor. There is a deep developmental groove where the talon’s cusp blends with the sloping lingual tooth surface that consists of a horn of pulp tissue. Exposure of pulp horn necessitates Endodontic therapy. • Dens invaginatus/dens in dente: It is a developmental variation caused by invagination within the crown or root of the lingual surface of tooth before calcification has occurred. Permanent maxillary incisors are the teeth more frequently involved, although may occur in other anterior teeth as well.



Figure 3.28 shows a radiograph showing dens in dente in maxillary left central incisor. Three types of Dens in Dente include: (Fig. 3.29) – Type I: It is minor type, lined by enamel that occurs within the crown and not extending beyond Cemento enamel junction (CEJ). – Type II: It consists of enamel lined blind sac that invades the root and may connect with the dental pulp. – Type III: It is the severe type which extends to the root and opens in the apical region but without connection with the dental pulp.

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Fig. 3.29  Diagrammatic representation of dens in dente types I, II, and III

Fig. 3.30  Diagrammatic representation of taurodontism in mandibular molars (Courtesy of Dr V.S. Mohan)

• Dens evaginatus: It appears as an accessory cusp or a globule of enamel on occlusal surface between buccal and lingual cusps of premolars, rarely on molars, canines and incisors. This extra cusp may contribute to pulp exposure with subsequent infection following occlusal wear or fracture. • Taurodontism: It is a dental anomaly in which the body of tooth is enlarged at the expense of the roots. On radiograph, the involved tooth appears rectangular in shape rather than taper toward the roots. The pulp chamber is extremely large and the usual constriction at the cervical of tooth is lacking and the roots are exceedingly short. Bifurcation/trifurcation may be present only few millimeters above the root apex. Figure 3.30 shows diagrammatic representation of taurodontism in mandibular molars and Figures 3.31A and B show the pre- and postoperative radiograph of pulpally involved mandibular molar with taurodontism. • Supernumerary roots: Extra roots than the usual may be present. Teeth that usually have single root, particularly mandibular premolars and canines, often have two roots. Molars also may exhibit one or more supernumerary root. Additional roots must be recognized on preoperative radiograph to accomplish Endodontic treatment properly. • Dentinogenesis imperfecta (Hereditary opalescent dentin): In type I and type II dentinogenesis Imperfecta, there is partial or total obliteration of the pulp chamber and root canals by continued formation of dentin. • Dentin dysplasia: Dentin dysplasia is a hereditary disease characterized by normal enamel but atypical

dentin formation with abnormal pulpal morphology. Roots are malformed in both the dentitions. In Radicular dentin dysplasia, obliterated pulp chambers are seen in both the dentitions. In coronal dentin dysplasia, obliterated pulp chambers in deciduous teeth and abnormally large pulp chambers in permanent teeth occur. • Palatal developmental groove: It originates from palatal surface usually the cingulum of maxillary lateral incisor and ends apically at various levels of root. • Additional root canals than the usual may be present. Figures 3.32A and B show radiographs of maxillary lateral incisor with four canals.

WHAT IS THE MORPHOLOGY OF THE ROOT CANAL SYSTEM OF THE INDIVIDUAL TEETH? Maxillary Central Incisor (Fig. 3.33) • Average length of tooth: 22.5 mm • Usual number of roots: 1 • Usual number of root canals: 1 (Lateral accessory canals may be present) • Root curvature: Mostly straight, but may be curved to labial or distal.

Morphology of Root Canal System Morphology of pulp chamber • Pulp chamber wider mesiodistally than buccolingually • Three pulp horns present in newly erupted central incisor

Morphology and Internal Anatomy of the Root Canal System

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B

Figs 3.31A and B  Taurodontism seen in a mandibular molar: (A) Preoperative radiograph showing deep caries involving the pulp (B) Postobturation radiograph (Courtesy of Dr Roheet Khatavkar)

Dotted line shows the outline for access cavity preparation

Fig. 3.33  Maxillary central incisor

A

B

A

B

Figs 3.32A and B  Preoperative and postoperative radiographs showing maxillary lateral incisor with four canals which were located, negotiated, cleaned and shaped and obturated (Courtesy of Dr V.S. Mohan)

Figs 3.34A and B  Preoperative and postoperative radiographs of maxillary central incisor tooth (Courtesy of Dr Roheet Khatavkar)

• Since there is single canal usually, the division between pulp chamber and root canal is indistinct • Floor is oval generally.

Possible Variation and Anomalies

Morphology of root canals • Cross-section at CEJ level is generally triangular in young teeth and oval in older teeth • Cross-section at apical level gradually becomes round. Figures 3.34A and B show the preoperative and postoperative radiographs of maxillary central incisor tooth.

• • • •

More than one main canal may be present. Dens invaginatus. Shovel shaped incisor crowns. Fusion, gemination.

Maxillary Lateral Incisor (Fig. 3.35) • Average length of tooth: 21 mm • Usual number of roots: 1

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Fig. 3.36  Postoperative radiograph of maxillary central and lateral incisor teeth (Courtesy of Dr Mrunalini Vaidya) Dotted line shows the outline for access cavity preparation

Fig. 3.35  Maxillary lateral incisor

• Usual number of root canals: 1 (about 5% cases have been reported to have 2 canals) (Lateral accessory canals may be present) • Root curvature: Mostly its root gets curved to the distal, sometimes straight.

Morphology of Root Canal System Morphology of pulp chamber • Pulp chamber wider mesiodistally than buccolingually • Similar to maxillary central incisor but smaller • Two pulp horns usually, sometimes pulp horns are absent. Morphology of root canals • When cross-section is taken at CEJ level, pulp chamber appears to be centered in the root • Cross-section at CEJ level is triangular or oval or round • Cross-section at midroot level is round • Cross-section at apical level is also round. Figure 3.36 shows the postoperative radiograph of maxillary central and lateral incisor teeth.

Possible Variation and Anomalies • Two roots may be present usually associated with a developmental radicular palatal groove. • Dens invaginatus or dens in dente. • Fusion, gemination. • Additional canals may be present.

Dotted line shows the outline for access cavity preparation

Fig. 3.37  Maxillary canine

Maxillary Canine (Fig. 3.37) • Average length of tooth: 26 mm (Longest root in dentition of approximately 17 mm length) • Usual number of roots: 1 • Usual number of root canals: 1 (Lateral accessory canals may be present commonly in the apical third of the root) • Root curvature: Mostly its root gets curved to the distal, sometimes straight or may be curved to the labial.

Morphology and Internal Anatomy of the Root Canal System

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Morphology of Root Canal System

Maxillary First Premolar (Fig. 3.39)

Morphology of pulp chamber • No pulp horns • Wider labiolingually than mesiodistally

• Average length of tooth: 20.6 mm • Usual number of roots: 2 • Usual number of root canals: 2 in most cases, 1 in few cases • Root curvature: Buccal root—mostly gets curved to the palatal sometimes may be straight or be palatally curved – Palatal root—mostly straight, sometimes may get curved to the buccal or distal – When there is single root, it is usually straight or may be distally or labially curved.

Morphology of root canals • Cross-section at CEJ level is oval shape. • Cross-section at mid-root is oval shape. • Cross-section at apical level shows constriction. Figures 3.38A and B show the preoperative and postoperative radiograph of maxillary canine.

Possible Variation and Anomalies • • • •

Dilacerated root Two roots Dens invaginatus Dens evaginatus

Morphology of pulp chamber • Wider buccolingually than mesiodistally • Buccal and palatal pulp horns present.

Clinical Considerations • Due to abscess in relation to maxillary canine, if perforation occurs below insertion of levator muscles of upper lip, abscess drains into buccal vestibule. If perforation occurs above insertion of levator muscles, drainage occurs in canine space resulting in cellulitis. • Occasionally, thin buccal bone over canine eminence disintegrates and fenestration occurs leading to clinical problems such as inaccurate apex location, risk of irrigation accident, slight permanent apical pressure sensitivity after root canal therapy.

A

Morphology of Root Canal System

B Figs 3.38A and B  Preoperative and postoperative radiographs of maxillary canine (Courtesy of Dr Roheet Khatavkar)

Morphology of root canals • When cross-section is taken in the coronal third, it appears to be kidney-shaped due to mesial concavity. • Cross-section at mid-root level is round shape. • Apical third generally has curved root canals. Figures 3.40A and B show the preoperative and postoperative radiographs of maxillary first premolar tooth. Figures 3.41A and B show the preoperative and postoperative radiographs of maxillary first and second premolars.

Dotted line shows the outline for access cavity preparation

Fig. 3.39  Maxillary first premolar

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A

B

Figs 3.40A and B  Preoperative and postoperative radiographs of maxillary first premolar tooth (Courtesy of Dr Roheet Khatavkar)

A

B

Figs 3.41A and B  Preoperative and postoperative radiograph of maxillary first and second premolars (Courtesy of Dr Roheet Khatavkar)

Possible Variation and Anomalies • More than two roots and root canals. • Canals may separate, may join, rejoin or divide. • Taurodontism has been reported in few cases.

Clinical Considerations • There is thin layer of bone separating the alveolar socket of maxillary first premolar from maxillary sinus. • Buccal root fenestration through the bone leading to clinical problems such as inaccurate apex location, risk of irrigation accident, slight permanent apical pressure sensitivity after root canal therapy. • Maxillary first premolar is susceptible to mesiodistal root fracture and fracture at the base of the cusps.

Maxillary Second Premolar (Fig. 3.42) • Average length of tooth: 21.5 mm • Usual number of roots: 1 • Usual number of root canals: 1 in most cases, 2 in few cases • Root curvature: Mostly the root is distally curved, sometimes may get curved to the buccal or to the distal.

Morphology of Root Canal System Morphology of pulp chamber • Wider buccolingually than mesiodistally • Buccal and palatal pulp horns are present, buccal pulp horn is larger.

Dotted line shows the outline for access cavity preparation

Fig. 3.42  Maxillary second premolar

Morphology of root canals: From floor of pulp chamber to the apex the cross-section is oval. When two canals are present, they are nearly parallel to each other since the tooth has one root usually. Figure 3.43 shows the postoperative radiograph of maxillary second premolar tooth with one canal. Figures 3.44A and B show the preoperative and postoperative radiograph of maxillary second premolar tooth with two canals.

Morphology and Internal Anatomy of the Root Canal System

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Possible Variation and Anomalies • • • •

Rare Dens invaginatus Deep distal root concavity Taurodontism has been reported.

Clinical Consideration • Maxillary second premolar is also susceptible to fractures like the maxillary first premolar.

Maxillary First Molar (Fig. 3.45)

Fig. 3.43  Postoperative radiograph of maxillary second premolar tooth (Courtesy of Dr Roheet Khatavkar)

• Average length of tooth: 20.8 mm (Largest tooth in volume) • Usual number of roots: 3 • Usual number of root canals – In 80% of cases, 4 namely the MB1, MB2, DB and palatal (Fig. 3.46B) – In 20% of cases, 3 namely the MB, DB and palatal (Fig. 3.46A) Clinical studies have shown that use of magnification in the form of loupes or dental operating microscope (DOM) has caused increased prevalence of the clinical detection of the MB2 canal. A clinical study by Buhrley et al (Ingle’s Endodontics 6, p.176) showed incidence of MB2 canals as follows: – Using DOM: 71.1% – Using loupes: 62.5% – Without any magnification: 17.2% • Root curvature – Mesiobuccal root is mostly distally curved, sometimes it may be straight

A

B Figs 3.44A and B  Preoperative and postoperative radiographs of maxillary fist premolar tooth (Courtesy of Dr Shivani Bhatt)

Dotted line shows the outline for access cavity preparation

Fig. 3.45  Maxillary first molar

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– Distobuccal root is mostly straight sometimes it may be curved to the mesial or distal – Palatal root is mostly curved to the buccal sometimes it may be straight.

Morphology of Root Canal System Morphology of pulp chamber • Its buccolingual dimension is widest. • Four pulp horns are present: MB, MP, DB, DP. • Cross-section of the floor of the pulp chamber is triangular (Molar triangle) when three canals are present as shown in Figure 3.46A. It is rhomboidal when four orifices are present, with corners corresponding to each of the four orifices as shown in Figure 3.46B. • Mesiobuccal orifice lies under the mesiobuccal cusp, distobuccal orifice lies distal and palatal to the MB orifice, Palatal orifice is centered palatally. There are two possible locations of the MB2 orifice: It may lie palatal and mesial to the main mesiobuccal orifice or it may lie on a line drawn from the main mesiobuccal orifice to the palatal orifice. Use of dental operating microscope or even loupes has resulted in increased prevalence of clinical detection of MB2 canal. Morphology of root canals • The palatal canal is flat and ribbon-like. • It has largest dimension and is wider mesiodistally. • Cross-section of the distobuccal canal is oval in the coronal two-thirds and round in the apical one-third. • MB1 and MB2 canals are closely interconnected and may sometimes merge into one canal. • Mesiobuccal root has a concavity on its distal aspect. So the root canal wall becomes thin in that area. As result, care has to be taken not to instrument the wall excessively because strip perforation can occur. Figures 3.47A and B show the preoperative and postoperative radiographs of maxillary first molar with three canals.

A



Figures 3.48A and B show the preoperative and postoperative radiographs of maxillary first molar with four canals.

Possible Variation and Anomalies • Two palatal canals have been reported (Fig. 3.49) • C-shaped canals • Taurodontism.

A

B

Figs 3.47A and B  Preoperative and postoperative radiographs of maxillary first molar with three canals (Courtesy of Dr Roheet Khatavkar)

A

B

Figs 3.48A and B  Preoperative and postoperative radiographs of maxillary first molar with four canals (Courtesy of Dr Shivani Bhatt)

B

Figs 3.46A and B  Occlusal view of maxillary first molar with three and four canals respectively

Fig. 3.49  Occlusal view of maxillary first molar with two palatal canals and two mesial canals (MB1, MB2)

Morphology and Internal Anatomy of the Root Canal System

Clinical Consideration • Pulp chamber of maxillary first molar lies mesial to the oblique ridge, so access cavity is usually confined mesial to oblique ridge in most cases. • Soreness can occur in maxillary teeth due to sinusitis or sinusitis can occur due to pulpal disease due to close proximity of maxillary sinus and because of thin buccal bony plate.

Maxillary Second Molar (Fig. 3.50) • • • •

Average length of tooth: 20 mm Usual number of roots: 3 Usual number of root canals: 3 or more, sometimes 2 or 1 Root curvature: – Mesiobuccal root is mostly curved to the distal sometimes it may be straight. – Distobuccal root is mostly straight sometimes it may be curved to the mesial or distal. – Palatal root is usually straight, sometimes it may be buccally curved.

Morphology of Root Canal System Similar to maxillary first molar with few differences such as shorter roots, less curvature and roots closer together. Morphology of pulp chamber • A flat triangle or a straight line is formed by the orifices. • The mesiobuccal canal orifice more to the buccal and mesial as compared to the first molar. • The palatal canal orifice lies on the most palatal aspect of the root. • The distobuccal orifice lies midway between the mesiobuccal and palatal orifice.

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Figure 3.51 shows the occlusal view of maxillary second molar with three canals, two canals and one canal. Morphology of root canals • There may be two, three or four root canals. • When two canals are present (seen in case of fused roots), they are generally parallel and of equal length and diameter. Figures 3.52A and B show the postoperative radiographs of maxillary second molar tooth with three and four root canals respectively.

Possible Variation and Anomalies • • • • •

Four roots; double palatal root Taurodontism Single rooted teeth with single canal (Fig. 3.51) C-shaped canals Two canal system-buccal and palatal (Fig. 3.51)

Clinical Consideration • Maxillary second molar lies closer to maxillary sinus than the first molar. Due to proximity of roots of maxillary second molar to the maxillary sinus, pulpal disease can cause sinusitis or sinusitis can cause soreness in maxillary teeth.

Maxillary Third Molar (Fig. 3.53) • Average length of tooth: 16.5 mm. • Usual number of roots and root canals: Extremely variable. 1 to 4 roots and 1 to 6 root canals, C-shaped canals.

Morphology of Root Canal System Morphology of maxillary third molar is unpredictable. Great variations in shape, size, form of both pulp chamber and root canal. Figure 3.54 shows the postoperative radiograph of maxillary third molar tooth.

Dotted line shows the outline for access cavity preparation

Fig. 3.50  Maxillary second molar

Fig. 3.51  Occlusal view of maxillary second molar with three canals, two canals and one canal respectively

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A

B Figs 3.52A and B  (A) Postoperative radiograph of maxillary second molar with three canals (Courtesy of Dr Ajay Bajaj); (B) Postoperative radiograph of maxillary second molar with four canals (Courtesy of Dr Mrunalini Vaidya)

Clinical Consideration • Two anatomic structures to which maxillary third molars lie close are the maxillary sinus and maxillary tuberosity. • Since maxillary third molars may be significantly tipped to distal, buccal or both, there can be great access problem. • Limited mouth opening can make root canal therapy almost impossible in maxillary third molar teeth. Dotted line shows the outline for access cavity preparation

Fig. 3.53  Maxillary third molar

Mandibular Central Incisor (Fig. 3.55) • Average length of tooth: 20.8 mm • Usual number of roots: 1 • Usual number of root canals: 1 or 2 canals which usually exit into a single apical foramen • Root curvature: Mostly it is straight, sometimes it may be curved to the distal or labially curved.

Morphology of Root Canal System Morphology of pulp chamber • Wider labiolingually than mesiodistally. • Oval-shaped which is narrow mesiodistally and long incisogingivally.

Fig. 3.54  Postoperative radiograph of maxillary third molar with three canals (Courtesy of Dr Shivani Bhatt)

Morphology of root canal • Cross-section at CEJ is oval • Cross-section at mid-root is ribbon-shaped • Cross-section at apical third is round

Morphology and Internal Anatomy of the Root Canal System

• When two root canals (buccal and lingual) are present, they usually join at the apical portion. Sometimes they exit as two separate canals (Fig. 3.56). Figure 3.57 shows the postoperative radiograph of mandibular central and lateral incisor teeth.

41

Clinical Consideration • Second canal is found lingual to the main canal. It should not be missed. • Due to lingual inclination of apex of mandibuar central incisor, surgical access may be difficult to achieve.

Possible Variation and Anomalies

Mandibular Lateral Incisor (Fig. 3.58)

• • • •

• Average length of tooth: 20.8 mm • Usual number of roots: 1 • Usual number of root canals: 1 or 2 canals which usually exit into a single apical foramen • Root curvature: Mostly it is straight, sometimes it may be curved to the distal or labially curved.

Two canals with single or separate foramina Dens invaginatus Fusion Gemination

Morphology of Root Canal System Almost similar to mandibular central incisors but slightly larger dimensions. Slight distolingual angulation of incisal edge should be considered. See Figure 3.57 for the postoperative radiograph of mandibular lateral incisor tooth.

Possible Variation and Anomalies • • • •

Two canals with single or separate foramina Dens invaginatus Fusion Gemination.

Mandibular Canine (Fig. 3.59) Dotted line shows the outline for access cavity preparation

Fig. 3.55  Mandibular central incisor

Fig. 3.56  Postoperative radiograph of mandibular central incisor with two canals (Courtesy of Dr V.S. Mohan)

• Average length of tooth: 25 mm • Usual number of roots: 1, sometimes 2

Fig. 3.57  Postoperative radiograph of mandibular central incisors and lateral incisor (Courtesy of Dr Ajay Bajaj)

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Dotted line shows the outline for access cavity preparation

Dotted line shows the outline for access cavity preparation

Fig. 3.58  Mandibular lateral incisor

Fig. 3.59  Mandibular canine

• Usual number of root canals: 1, sometimes 2 • Root curvature: Mostly it is straight, sometimes it may be curved to the distal or labial.

Morphology of Root Canal System Morphology of pulp chamber • Similar to maxillary canine but smaller dimensions • Single pulp horn present • Narrow mesiodistally • Floor is ovoid in shape. Morphology of root canals • Narrow mesiodistally than buccolingually • It may have two roots and two root canals. Figure 3.60 shows the postoperative radiograph of mandibular canine tooth.

Possible Variation and Anomalies • Two-rooted canine with two canals has been reported • Dens evaginatus • Fusion.

Clinical Consideration • Buccal wall larger, lingual wall slit-like poses a challenge to clean and shape.

Fig. 3.60  Postoperative radiograph of mandibular canine (Courtesy of Dr Nilesh Kadam)

Mandibular First Premolar (Fig. 3.61): Enigma to Endodontist • Average length of tooth: 21.6 mm • Usual number of roots: 1, sometimes 2 or 3 • Usual number of root canals: 1, sometimes bifurcated canals which join at apical third • Root curvature: Usually it is straight, sometimes it may be curved to the distal or buccal.

Morphology and Internal Anatomy of the Root Canal System

Morphology of Root Canal System Morphology of pulp chamber • Wider buccolingually than mesiodistally • Two pulp horns present. Lingual pulp horn is small and rounded • Lingual inclination of crown makes location of lingual orifice difficult.

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Morphology of root canals • When single canal is present, it has oval outline • When two canals are present, they have round shape from pulp chamber to the apical foramen. The lingual canal diverges from the main canal at a sharp angle. • Sometimes may have three root canals with C-shaped canal anatomy. • In some cases, a single broad root canal may bifurcate into two separate root canals. Figures 3.62 to 3.64 show postoperative radiographs of mandibular first premolar.

Dotted line shows the outline for access cavity preparation Fig. 3.61  Mandibular first premolar

Fig. 3.63  Postoperative radiograph of mandibular first premolar showing lateral canals filled too (Courtesy of Dr Shivani Bhatt)

Fig. 3.62  Postoperative radiograph of mandibular first premolar (Courtesy of Dr Nilesh Kadam)

Fig. 3.64  Postoperative radiograph of mandibular first premolar with moderate J-shaped curvature in the apical part of the root (Dilaceration) (Courtesy of Dr Roheet Khatavkar)

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Possible Variation and Anomalies • Numerous variations in root canal morphology occur in mandibular first premolar and access to its second canal is difficult. This is the possible reason for the highest failure rate in mandibular first premolar of nonsurgical root canal therapy • Gemination • Dens invaginatus • Dens evaginatus • Two roots, three roots • Two canals in single root • Three canals with fused roots • Three canals in single root • Three canals with two roots • Three canals with three roots. Due to numerous variations in the root canal morphology and highest chances of failure, the mandibular first premolar is termed as an enigma to Endodontist.

Clinical Consideration • Due to lingual inclination of crown, access cavity may need to be extended upto cusp tip, to gain straight line access. Location and negotiation of lingual canal becomes difficult. • Due to close proximity of root apex of mandibular first premolar to mental canal and foramen, sometimes periapical radiolucency on radiograph must be differenciated from periapical pathology.

• Surgical access of mandibular first premolar is complicated due to proximity to mental nerve.

Mandibular Second Premolar (Fig. 3.65) • • • •

Average length of tooth: 22.3 mm Usual number of roots: 1 Usual number of root canals: 1 Root curvature: Mostly straight, sometimes may be curved to the distal or buccal.

Morphology of Root Canal System Morphology of pulp chamber • Wider buccolingually than mesiodistally • Similar to mandibular first premolar but lingual pulp horn may be larger. Morphology of root canals: Oval shaped root canals. Figure 3.66 shows the postoperative radiograph of mandibular second premolar tooth.

Possible Variation and Anomalies • Similar to first premolar but found less often. Figures 3.67A and B show the preoperative and postoperative radiographs of mandibular second premolar with additional root and root canals.

Mandibular First Molar (Fig. 3.68) • Average length of tooth: 21 mm • Usual number of roots: 2, sometimes 3 • Usual number of root canals: 3 or 4 usually, sometimes more

Dotted line shows the outline for access cavity preparation

Fig. 3.65  Mandibular second premolar

Fig. 3.66  Postoperative radiograph of mandibular second premolar tooth (Courtesy of Dr Shivani Bhatt)

Morphology and Internal Anatomy of the Root Canal System

45

A Dotted line shows the outline for access cavity preparation

Fig. 3.68  Mandibular first molar

B Figs 3.67A and B  Preoperative and postoperative radiographs of mandi­bular second premolar with additional root and root canals (Courtesy of Dr Roheet Khatavkar)

• Root curvature: – Mesial root : Mostly gets curved to the distal sometimes straight. – Distal root: Mostly straight, sometimes may be curved to the distal.

Morphology of Root Canal System Morphology of pulp chamber • Four pulp horns are present: MB, ML, DB, DL • Roof of pulp chamber is located in cervical third of root and is rectangular in shape. • Floor of pulp chamber is located in cervical third of root and is rhomboidal in shape. • Mesiobuccal canal orifice is located under the mesiobuccal cusp • Mesiolingual orifice is found just lingual to central groove • Distal orifice is located distal to buccal groove. Figure 3.69 shows occlusal view of mandibular first molar with three, four and five canals respectively.

Fig. 3.69  Occlusal view of mandibular first molar with three, four and five canals respectively

Morphology of root canals • Cross-section of all canals is ovoid in cervical and middle thirds and round in the apical third. • Mesial root usually has two canals—MB and ML. Sometimes, a third canal called middle mesial (MM) (Figs 3.69 and 3.71) is found between the two mesial canals. Mesial root canals are curved; MB canal having the greatest curvature. • Distal root may have a single canal or two canals—DB and DL are present. Sometimes a third canal middle distal may be present. Figures 3.70 to 3.72 show radiographs of mandibular first molar tooth.

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A

A

B

B

Figs 3.70A and B  Preoperative and postoperative radiographs of mandibular first molar tooth (Courtesy of Dr Shivani Bhatt)

Figs 3.72A and B  Preoperative and postoperative radiographs of mandi­bular first molar with radix entomolaris (Courtesy of Dr Nilesh Kadam)

Possible Variation and Anomalies • Additional canals in one or more roots • Supernumerary roots and canals. An additional root on the lingual aspect (radix entomolaris) has been reported. Figures 3.72A and B show the preoperative and postoperative radiographs of a mandibular molar with additional lingual root (Radix entomolaris) • Taurodontism • C-shaped canals. A

B

Figs 3.71A and B  Preoperative and postoperative radiographs of mandi­bular first molar with three mesial canals (Courtesy of Dr Roheet Khatavkar)

Clinical Consideration • Multiple accessory foramina are present in the furcation of mandibular molars.

Morphology and Internal Anatomy of the Root Canal System

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Dotted line shows the outline for access cavity preparation Fig. 3.73  Mandibular second molar Fig. 3.74  Occlusal view of mandibular second molar with three canals, four canals, two canals and C-shaped canals

• The distal surface of the mesial root and the mesial surface of the distal root have a root concavity making dentinal wall very thin. Instrumentation against these walls should be minimized to prevent strip perforation.

Mandibular Second Molar (Fig. 3.73) • • • •

Average length of tooth: 19.8 mm Usual number of roots: 2 Usual number of root canals: 3, sometimes 2 Root curvature – Mesial root: Mostly curved to the distal, sometimes may be straight – Distal root: Mostly straight, sometimes may be curved to distal or mesial or buccal – Mesial and distal roots usually sweep distally in a gradual curve with their apices closer together – When there is single root, it is usually straight sometimes may get curved to distal or lingual.

Morphology of Root Canal System Morphology of pulp chamber • Similar to mandibular first molar but more symmetric. • Smaller size of pulp chamber and canal orifices as compared to mandibular first molar. • Two mesial orifices located closer together. • C-shaped canals commonly occur in mandibular second molar. Figure 3.74 shows occlusal view of mandibular second molar with three canals, four canals, two canals and C-shaped canals respectively.

Morphology of root canals • Cross-section is ovoid in cervical and middle third • Cross-section is round in apical third • Sometimes shows two canals connected by a semicircular slit or C-shaped canal. Figures 3.75 to 3.77 show the radiographs of mandibular second molar tooth.

Possible Variation and Anomalies • One to six canals. Most common configurations are two, three and four canals • Additional canals in one or more of roots • Supernumerary roots • Fused or single root • Taurodontism.

Clinical Consideration • Multiple accessory foramina are present in the furcation of mandibular molars • The distal aspect of the mesial root of mandibular second molar and the mesial aspect of the distal root have a root concavities where careful instrumentation needs to be done.

Mandibular Third Molar (Fig. 3.78) • Average length of tooth: 17.5 mm • Usual number of roots and root canals: 2

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B

A A

Figs 3.77A and B  Preoperative and postoperative radiographs of mandi­bular second molar with C-shaped canal (Courtesy of Dr Roheet Khatavkar)

B Figs 3.75A and B  Preoperative and postoperative radiographs of mandibular second molar tooth (Courtesy of Dr Shivani Bhatt)

Dotted line shows the outline for access cavity preparation

Fig. 3.78  Mandibular third molar

• Fused, short, severely curved or malformed roots. 1–4 roots and 1–6 canals, C-shaped canals may be present.

Morphology of Root Canal System The morphology of mandibular third molar is unpredictable. It resembles mandibular first and second molar but with numerous variations. Figures 3.79A and B show the preoperative and postoperative radiographs of mandibular third molar tooth showing curved canals.

Clinical Considerations Fig. 3.76  Postoperative radiograph of mandibular second molar with C-shaped canal (Courtesy of Dr Shivani Bhatt)

• Anatomic structure that lies close to the roots of mandibular third molar is mandibular canal.

Morphology and Internal Anatomy of the Root Canal System

A

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B Figs 3.79A and B  Preoperative and post-operative radiograph of mandibular third molar showing curved canals (Courtesy of Dr Nilesh Kadam)

• Accessibility may be a problem due to its location • Isolation and moisture control is difficult.

BIBLIOGRAPHY 1. Cohen S, Hargreaves KM. Pathways of Pulp, 9th edn. St. Louis: Mosby, 2006. pp.148-65,193-232.

2. Grossman L, Oliet S, Del Rio C. Endodontic Practice, 11th edn. Varghese Publication, 1991. pp.29-58. 3. Ingle J, Bakland L, Baumgartner J. Ingle’s Endodontics, 6th edn. BC Decker Inc, Hamilton, 2008. pp. 151-220. 4. Jafarzadeh H, You-Nong. The C-shaped root canal configuration: A Review, JOE. 2007;33:5. 5. Shafer W, Hine M, Levy B. A Textbook of Oral Pathology, 4th edn. WB Saunders Company, 1993. pp.38-45.

CHAPTER

4

The Pulpal Reactions to Caries and Dental Procedures

This chapter explains how the reaction of pulp to various external stimuli is unique and describes in detail the reaction of pulp to dental caries and various dental procedures.   You must know • How is the Response of Dental Pulp Unique and Different from Other Connective Tissues of the Body? • Which are the Different External Stimuli that can Affect Dental Pulp? • How does the Pulp React to Dental Caries? • How does the Pulp React to Dental Procedures? – How does the Pulp React to some of the Diagnostic Procedures? – How does the Pulp React to Treatment Procedures? • How does the Pulp React to Specific Dental Materials?

HOW IS THE RESPONSE OF DENTAL PULP UNIQUE AND DIFFERENT FROM OTHER CONNECTIVE TISSUES OF THE BODY? Pulpal response to external stimuli is unique due to following reasons: • Pulp is encased within the hard tissues, in an unyielding low-compliance environment • Pulp has limited space to expand during inflammation • Pulp has limited portals of entry • Pulp is an organ of terminal and limited circulation with no efficient collateral circulation • Pulp is more susceptible to injury and may have complicated regeneration due to scarcity of circulation • Even the mature pulp resembles embryonic connective tissue. Therefore, it is relatively rich source of stem cells. It has the ability to form dentin throughout life • Rich neurovascular supply within the pulp may promote the effect of inflammation and can lead to rapid degeneration and necrosis of pulp • Various dental treatment procedures involve cleaning and shaping of enamel and dentin, causing further irritation of pulp

• Bacteria enter the pulp at a very late stage. Initially there is invasion of bacterial products and toxins rather than bacteria themselves • Pulp organ lacks specific receptors for different external stimuli, the sensory response is always pain irrespective of the type of stimulus-heat, cold, pressure, touch, etc. A mind-map to remember all unique features of dental pulp is given in Figure 4.1.

WHICH ARE THE DIFFERENT EXTERNAL STIMULI THAT CAN AFFECT THE DENTAL PULP? Flow chart 4.1 gives the detailed list of external noxious stimuli that can affect the dental pulp causing its inflammation, necrosis and dystrophy beginning with the most frequent irritant: Micro-organisms. These have been discussed in detail in the next chapter under the possible causes of diseases of dental pulp.

HOW DOES THE PULP REACT TO DENTAL CARIES? Dental caries is a polymicrobial disease affecting the dental pulp. Bacteria are mainly responsible for causing pulpal disease.

The Pulpal Reactions to Caries and Dental Procedures

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Fig. 4.1  Mind-map of unique features of dental pulp

Pathways of Bacterial Invasion of the Pulp

Dentin Sclerosis: Decrease in Dentin Permeability

Figure 4.2 shows different pathways through which there is invasion of bacteria and toxins into the pulp. Initially, there is invasion of bacterial toxins and invasion by bacteria themselves occurs at later stages of the carious process that clinically present as carious exposure. This is because toxins pass through enamel and dentin well ahead of bacteria themselves. Bacterial byproducts and toxins include: • Acids and proteinases that dissolve and digest enamel and dentin • Lipopolysaccharides (LPS) • Lipoteichoic acid (LTA).

First defense reaction to caries is dentin sclerosis. This occurs by: • Increased deposition of intratubular dentin. Transforming growth factor-beta 1 (TFG-beta 1) has been implicated to be mainly responsible for this reparative dentinogenesis. • Direct deposition of precipitated mineral crystals into the narrowed dentinal tubules causing occlusion of tubules. As a result, there is effective decrease in dentin permeability occurring in a relatively short period of time.

Reaction of Pulp to Dental Caries Pulp exhibits inflammatory reaction in response to bacteria and their byproducts and toxins. • To protect dental pulp against caries, three basic reactions occur in the following sequence: – Dentin sclerosis: Decrease in dentin permeability – Formation of tertiary dentin – Inflammatory and immune reactions.

Formation of Tertiary Dentin This occurs over a longer period of time as compared to sclerotic dentin. Resultant character of tertiary dentin depends on the intensity of stimulus. Either reactionary or reparative dentin is formed (Fig. 4.3). • In response to mild stimulus, resident quiescent odontoblasts are activated forming reactionary dentin. This mostly is seen in cases where dentin

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Short Textbook of Endodontics Flow chart 4.1  Noxious stimuli affecting dental pulp/causes of diseases of dental pulp

Fig. 4.2  Pathways of bacterial invasion into the pulp

Fig. 4.3  Diagram showing effect of caries on pulp. a: Bacterial plaque; b: Outer carious dentin; c: Transparent inner carious dentin; d: Reparative dentin; e: Pulp

The Pulpal Reactions to Caries and Dental Procedures

demineralization has occurred beneath the noncavitated enamel lesion. • In response to aggressive stimulus, the subjacent odontoblasts die and there is disruption of odontoblast layer. As a result, there is differentiation of secretory cells to cause repopulation of the disrupted odontoblast layer either by – Organized tubular reparative dentin or – Disorganized irregular fibrodentin. Sclerotic and tertiary dentin formed provides a physical barrier to noxious stimuli.

Inflammatory and Immune Reactions Inflammation • Acute inflammation: Polymorphonuclear (PMN) leukocytes reach the area of bacterial involvement to prevent the further dissemination of bacteria deeper into the pulp. In case of severe inflammatory process, symptoms of acute reaction are manifested. – There is accumulation of inflammatory exudates, causing pain from pressure on nerve endings. – As the PMN leukocytes die, there is formation of pus which further irritates the nerve cells. • Chronic inflammation: In case of less severe inflam­ matory process, PMN leukocytes are replaced by lymphocytes and plasma cells. The inflammatory reaction is confined to the surface of the pulp. – Microorganisms may penetrate deeper causing an acute exacerbation manifested by clinical flare-up. – Microorganisms may cause reaction in the periapical tissue by means of their metabolic products. Chronic inflammation due to deep dental caries involving the pulp appears radiolucent on intraoral periapical radiograph (IOPA) as seen in Figure 4.4.

A

B

C

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• Chronic hyperplastic pulpitis: In case of primary and immature permanent teeth, pulp exposure can result in a proliferative pulpal response called chronic hyperplastic pulpitis characterized by proliferation of exuberant inflammatory pulp tissue through the exposure forming pulp polyp. • Pulp necrosis: In case of persistent inflammation, tissue pressure is increased, stasis occurs resulting in pulp necrosis. Whether partial or total necrosis of pulp occurs is determined by possibility of drainage. In case of pulp open to oral fluids, drainage is possible. So, partial necrosis is likely to occur. Apical pulp tissue remains uninflammed. But if drainage is not possible, total necrosis of pulp may occur. Figure 4.5 shows diagrammatic representation of sequel of dental caries, how it affects the dental pulp and the periradicular area demonstrating caries in enamel and dentin becomes deeper and causes inflammation in

Fig. 4.4  Radiograph showing mandibular first molar with extensive caries involving the pulp (Courtesy of Dr Chetan Shah)

D

E

Figs 4.5A to E  Diagrammatic representation of sequel of dental caries: (A) Caries in enamel and dentin; (B) Deep caries causing pulpitis; (C) Widening of the periodontal ligament space; (D) Periapical granuloma or abscess; (E) Necrotic pulp and periapical abscess

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the pulp. There is widening of the PDL space. Persistent inflammation causes necrosis of the pulp. Less virulent microorganisms may result in formation of chronic abscess. Low grade irritation can result in the formation of periapical granuloma or cyst. Immune Reactions • Humoral and cellular pulpal immune response occurs to invading microorganisms. • Immunoglobulins such as IgG, IgM and IgA have been found within the odontoblasts of carious dentin. • The three antigen-presenting cell types of pulp include: – Macrophages – Dendritic cells – B-lymphocytes. Macrophages express type II major histocompatibility complex (MHC) molecules on stimulation of bacteria or cytokines. Dendritic cells form network around blood vessels within the pulp and the odontoblast layer and constantly express MHC molecules without provocation. B-lymphocytes secrete antibodies during specific immune response and express MHC molecules. Initially, antibodies accumulate in the odontoblast layer. But as the lesion progresses, they may be found in dentinal tubules. • The first cells to encounter an antigen diffusing along the dentinal tubules are the odontoblasts. The odontoblasts are stationary and do not directly participate in the activation of T-cells, but may have a role in activating dendritic cells. • Calcification and internal resorption: Formation of pulp stones and calcific metamorphosis has been found to occur in response to caries in chronic long standing cases. Calcific metamorphosis – A pulpal response to traumatic injury characterized by deposition of hard tissue within the root canal space is called calcific metamorphosis. – Calcific metamorphosis commonly occurs in the anterior teeth that get affected by trauma. – A tooth with calcific metamorphosis appears darker in hue than the adjacent teeth and has dark yellow color due to greater thickness of dentin. – There is reduction in size of both the coronal and radicular pulp spaces, sometimes resulting in partial or total obliteration of pulp canal when seen on radiograph. PDL space is normal and lamina dura is intact.

– Calcific metamorphosis progresses from coronal part of the tooth to the apical canal. An alternative sequela to trauma may be idiopathic internal resorption. • Repair and regeneration: When inflammatory and immune reactions are effective, the foreign material may be neutralized and removed, initiating repair and regeneration. • There is formation of reactionary (tertiary) dentin, when no odontoblasts are killed. • There is formation of reparative (tertiary) dentin, when odontoblasts are killed. However, normally organized pulp may not reform. Pulp polyp is considered as a chronic inflammation in which injury and repair are going on at the same time. Pulp polyp contains epithelial cells from oral mucosa, large lymphocytes and also fibrous tissue. Figure 4.6 shows a photograph of pulp polyp in a primary second molar. Lymphocytes represent cells of inflammation. Fibrous tissue represents an attempt to ‘wall off’ the diseased tissue, i.e. repair. A mind-map to remember all points of reaction of pulp to dental caries (Fig. 4.7).

HOW DOES THE PULP REACT TO DENTAL PROCEDURES? Flow chart 4.2 shows different diagnostic and dental treatment procedures.

Fig. 4.6  Photograph showing pulp polyp in a primary second molar (Courtesy of Dr CR Suvarna)

The Pulpal Reactions to Caries and Dental Procedures

Fig. 4.7  Mind-map of reaction of pulp to dental caries

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Short Textbook of Endodontics Flow chart 4.2  Different diagnostic and dental treatment procedures

The maximum temperature at the pulp-dentin junction (PDJ) was recorded using a thermistor and found to be about 9.5oC for 5-minute application. When carbon dioxide snow was applied to the tooth for 20 minutes, the pulp suffered damage and there was necrosis of odontoblasts. Thus, within normal clinical parameters (temperature and time) cold test is relatively safe and does not cause any pulpal damage. It has been found that value of 10 oC above body temperature is considered as threshold to cause irreversible damage to vital tissues. Higher temperatures and greater time of application leads to greater damage.

How does the Pulp React to Dental Treatment Procedures? How does the Pulp React to Local Anesthetics?

How does the Pulp React to Some of the Diagnostic Procedures? Pulp Vitality Testing Thermal tests: Both heat and cold tests if performed within normal clinical parameters do not cause any damage to dental pulp.

Heat Test Heated gutta-percha or tip of heat-testing device such as system B reaches a temperature of 200oC, just before the smoke point and is applied to the tooth surface for 5–10 seconds. The maximum temperature at the pulp-dentin junction (PDJ) was recorded using a thermistor and found to be about 39.9oC for 10 second application of heat to tooth. This temperature does not reach the threshold at which damage to the tissue can occur. Thus, within normal clinical parameters (temperature and time) heat test is relatively safe and does not cause any pulpal damage.

• Vasoconstrictors, such as epinephrine, which are added to local anesthetics to enhance its duration of action, cause reduction in pulpal blood flow (Fig. 4.8). • Reduction in pulpal blood flow can have a negative effect on the health of dental pulp as it reduces the clearance of large molecular weight toxins or waste products that may result in irreversible pulpal pathosis. This effect is more likely particularly if the pulp is inflamed preoperatively. • During cavity preparation in an anesthetized tooth, the response of pulp is suboptimal. If the pulp is already severely inflamed, local anesthesia compromises its ability to recover from inflammation. • Supplemental injections (such as intraosseous, intra­ ligamentary and intrapulpal) cause more severe reduction or even transient cessation of pulpal blood flow. This has been concluded from animal studies. • During Endodontic access preparation, if in spite of nerve block and repeated supplemental injections, if pain persists, then intrapulpal injection is indicated. It is achieved by injecting the anesthetic into pulp tissue under pressure. The pharmacologic action of anesthetic solution occurs on nerve cell membrane. Mechanical pressure of injection causes circulatory interference. If anesthetic solution is deposited passively into the pulp chamber, the solution will not diffuse throughout the pulp and hence is ineffective.

Cold Test

How does the Pulp React to Ultrasonic Scaling and Periodontal Procedures?

Carbon dioxide snow has an inherent temperature of –78oC  that may be applied to tooth surface for 5 seconds to 5 minutes.

Heat is generated during ultrasonic scaling which has the potential to cause pulpal damage if adequate cooling with water coolant is not used (Fig. 4.9).

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Fig. 4.8  Reaction of pulp to local anesthetics

Fig. 4.10  Reaction of pulp to ultrasonic scaling of some teeth

Fig. 4.9  Reaction of pulp to inadequate water during periodontal procedures

There is greater amount of heat generated with heavy load of force exerted by the ultrasonic tip against the tooth. Thus, proper water cooling of ultrasonic scalers is a must to control the excessive heat production and prevent any damage to pulp. Also, periodontal scaling and root planing may result in removal of thin cementum that exposes the dentin to the oral cavity resulting in dentin hypersensitivity. Thus, periodontal disease that causes attachment loss and exposes root surface to oral cavity as well as periodontal treatment such as scaling and root planning can be associated with pulpal pathosis particularly if large lateral or accessory canals are exposed (Fig. 4.10).

How does the Pulp React to Cavity and Crown Preparation? The physical irritation of the pulp from heat, desiccation or vibration while performing restorative procedures may affect the pulp adversely.

Fig. 4.11   Factors affecting amount of heat produced during cavity and crown preparation

Factors Affecting Amount of Heat Produced during Cavity and Crown Preparation (Fig. 4.11) i. Length of time of contact of cutting instrument with the tooth structure, if more, then can cause lots of heat production. Intermittent cutting is recommended.

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ii. Sharpness of bur: Old blunt burs may require application of lots of pressure for cutting. iii. Amount of pressure exerted on bur: Light pressure is recommended. More pressure can cause more heat production. iv. Revolutions per minute. v. Nature of cutting instrument: Steel burs produce more heat as compared to carbide burs causing more thermal damage to the pulp. Diamond burs cause abrasive action and pressure may need to be exerted. Damaged or improper handpiece with poor torque characteristics can cause pulpal damage due to eccentric bur rotation. vi. Cooling method: When only air is used as coolant, more potential for pulpal damage. When water is used as coolant, less chances of pulpal inflammation.   If only air is used as coolant at 2,00,000 rpm, it has been found that it takes just 11 seconds of continuous preparation at this speed to burn the pulp. The density of dentinal tubules at DEJ is 65,000/mm2 and the density of dentinal tubules at the pulp is 15,000/mm2. As the remaining dentinal thickness (RDT) decreases, the response of pulp to restorative procedures increases.

Remaining Dentinal Thickness • It is the thickness of dentin present between the floor of cavity preparation and the roof of the pulp chamber. • It is an important factor in determining the pulpal response to various noxious stimuli. • Dentin thickness of about 2 mm between the floor of cavity preparation and the pulp is considered adequate to serve as an insulating barrier against irritants. • Permeability of dentin increases with lesser remaining dentinal thickness (RDT). It has been found that when RDT is about 0.75 mm, effects of bacterial invasion are seen and when RDT is about 0.25 mm, odontoblastic cell death is seen Figures 4.12A and B show diagram of cavity preparation is madibular molar with more RDT in (A), less possibility of damage to pulp and lesser RDT in (B) where there will be increased pulpal response. Thus, RDT of less than 0.5 mm, can cause severe pulpal reaction and more chance of pulp undergoing irreversible pulpal pathosis. Dentin is a good insulator, damage to pulp does not occur unless RDT is less than 1 mm. In case of large and wide cavity preparation and extensive preparation for crown, more dentinal tubules are exposed to external microbial or chemical irritation. If adequate water coolants are not used during such preparations, there can be marked reduction in pulpal blood flow.

A

B Figs 4.12A and B  (A) More RDT; (B) Lesser RDT Abbreviation: RDT, remaining dential thickness

The diameter of dentinal tubules at DEJ is 0.6–0.8 µm and the diameter of dentinal tubules at pulp is 3 µm. Bacterial cells have diameter of 0.5–1 µm and can migrate through remaining dentin into pulp. To minimize the liberation of heat during preparation: • Use ultrahigh speeds of rotation for Enamel and superficial dentin. • Use efficient water cooling system. • Use light pressure. When using high speed, instru­ mentation pressure should not be more than four ounce and when using low speed, instrumentation pressure should not be more than twelve ounce. • Do intermittent cutting. Remember that the bur-dentin interface must always be wet. • Finish the crown/cavity preparation using low-speed cutting and hand instruments.

How does the Pulp React to Drying of Tooth? Rapid, prolonged blast of air causes rapid outward flow of dentinal fluid into patent dentinal tubules which stimulates the nociceptors in dental pulp producing pain (Fig. 4.13). Also, odontoblasts are aspirated into the tubules. These displaced cells undergo autolysis and disappear within a short-time. They are replaced by new odontoblasts from stem cells deeper in the pulp which are capable of producing tertiary dentin. Some harsh chemicals such as lipid solvents-like acetone or ether have been used in the past to clean cavity floors. But they were found to produce strong hydrodynamic forces in dentinal tubules causing odontoblast displacement.

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Fig. 4.13  Reaction of pulp to drying of tooth

Fig. 4.14  Reaction of pulp to acid-etching of dentin

It is recommended that cavity floors be dried with cotton pellets and short blasts of air rather than harsh chemicals. In deep cavities, air blast can cause lots of discomfort to the patient. Cotton pellets should be used. Also, the tooth must be kept moist during preparation and while drying the cavity preparation, care must be taken just to remove extra moisture from the operative field and not remove dentin’s natural moisture (desiccation).

If the open dentinal tubules are left unsealed, the irritants can diffuse into the pulp and may intensify and prolong the severity of pulpal reactions. In superficial cavities, diameter of dentinal tubules is narrow and density of peripheral dentin is low, so etching of dentin followed by adequate sealing with restorative resin will not cause any detrimental effects on pulp. In case of deep cavities or presence of exposure, phosphoric acid etching can be detrimental. Also, in cases where phosphoric acid etching is done and bacteria are also present, severe pulpal inflammation and necrosis tends to occur. Due to such effects with total etch systems, self-etching systems have become popular these days which eliminate etching with phosphoric acid. They do not remove the smear layer but this smear layer is incorporated within the restoration. But the only drawback of self-etch system is that it may form a relatively poor bond due to weaker acidity of acidic primers of self-etch system than total etch system.

How does the Pulp React to Cavity Cleansing and Sterilization? Certain caustic chemicals such as hydrogen peroxide, sodium hypochlorite, calcium hydroxide, etc. were used in the past for cavity disinfection to get rid of residual microbial contamination of the cavity preparation. But these chemicals may be potentially toxic to the pulp and so they are not used these days. When dentin is exposed, there is outward flow of dentinal fluid, so the inward flow of any noxious agents is minimized. As a result, the irritation from residual microbial contamination in dentinal tubules is reduced.

How Does the Pulp React to Acid Etching of Enamel and Dentin? When dentin is cut, smear layer is produced containing fragments of microscopic mineral crystals and organic matrix. Smear layer blocks the orifices of dentinal tubules and reduces the permeability of dentin. Etching of dentin with phosphoric acid removes the smear layer and causes demineralization of surface layer of collagen (Fig. 4.14).

How does the Pulp React to Cementation of Crown or Bridge? When cementation of crowns, inlays or bridges is done on vital teeth, hydraulic forces may be exerted on the pulp as cement compresses the fluid in dentinal tubules. • Gentle and careful cementation must be done in case of vital teeth • Vents are provided in the casting that allow the cement to escape and facilitate seating.

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How does the Pulp React to Vital Bleaching Techniques? Strong oxidizing agents such as 10% carbamide peroxide and hydrogen peroxide are used to bleach enamel of vital teeth. These chemicals are in contact with teeth for long duration, i.e. overnight and they may cause mild pulpitis that usually gets reversed within 2 weeks. This occurs particularly if dentin with open tubules or cracks is present. The symptoms usually are reversible and can be prevented by treating the teeth with fluorides and by doing the necessary restorative treatment preoperatively.

How does the Pulp React to Polishing of Restorations? • When glass ionomer and composite restorations are polished, no significant increase in temperature at the pulp-dentin interface has been found. • But polishing of amalgam restorations, especially with high speed, high contact pressure and no coolant can cause increased temperatures that may be damaging. If water coolant is not to be used, it is recommended that speed should not exceed 4000 rpm. It is safer to use a coolant, apply light pressure and inter­ mittent contact during polishing of amalgam restoration to prevent any likely pulpal damage.

How does the Pulp React to Cavity Preparation using Air Abrasion? Air abrasion is a conservative, nonpainful cavity preparation technique that forces aluminum oxide particles in a rapid stream onto tooth structure and is simultaneously evacuated from the field. If higher pressure and small particle size is used, there are fewer pulpal effects as compared to high-speed burs. Air-abrasion technique can be used in case of shallow caries and in pediatric patients.

How does the Pulp React to Orthodontic Tooth Movement? Orthodontic forces cause changes in pulpal blood flow not only of teeth undergoing active movement but also of adjacent teeth (Fig. 4.15). Thus, the pulpal response to orthodontic forces is hemodynamic. Heavy forces used to reposition malaligned teeth especially impacted canines may lead to pulp necrosis or calcific metamorphosis.

Fig. 4.15  Reaction of pulp to orthodontic tooth movement

Some of the methods used for removal of orthodontic brackets at the completion of treatment have been found to cause injury to pulp.

How does the Pulp React to Laser Procedures? • Commonly used lasers in dentistry include Er:YAG, Nd:YAG and CO2 lasers • Er:YAG laser is used for removal of caries and cutting dentin. Lower energy delivered through low power settings with Er:YAG laser is found to produce favorable results • CO2 laser can be used for pulpotomy procedure in primary teeth, pulpotomy procedures in permanent teeth with immature apex and in exposed pulps due to fracture • Nd:YAG laser can be used for pulp and in surgery • The pulpal responses to Nd:YAG and CO2 lasers are not found to be favorable. They may cause charring and significant inflammation in pulp compared to Er:YAG laser.

How does the Pulp React to Specific Dental Materials? The effects of dental materials on pulp may be related to the permeability of associated dentin which in turn may be affected by the thickness of dentin remaining (RDT) between the cavity preparation and the pulp.

Zinc Oxide Eugenol Zinc oxide eugenol (ZOE) has anesthetic and antiseptic properties. When ZOE is applied to deep cavities, it blocks transmission of action potentials in nerve fibers and

The Pulpal Reactions to Caries and Dental Procedures

suppresses nerve excitability in the pulp. It adapts well to dentin and inhibits bacterial growth on cavity walls. Zinc oxide eugenol is suitable as temporary filling but not long-term restoration as it has been found to leak over a period of time.

Zinc Phosphate Cement The phosphoric acid liquid phase may be harmful to the pulp. But studies have shown that it is relatively safe. Zinc phosphate cement has been used as base beneath amalgam restorations for years. Zinc phosphate is also well-tolerated by pulp when used as a luting agent.

Glass Ionomer Cement When glass ionomer cement is used as liner in deep cavities with RDT of 0.5–0.25 µm, it results in deposition of tertiary dentin but at a slower rate than calcium hydroxide. When glass ionomer cement is placed over exposed healthy pulp, there is severe pulpal inflammation or necrosis similar to that for calcium hydroxide. When glass ionomer cement is used as luting agent in vital teeth, for sometime after luting, there is postcementation sensitivity which subsides over a period of time.

Silver Amalgam Amalgam cannot be placed directly over the cavity preparation, it has to be placed over a liner/base such as zinc phosphate cement to protect the pulp. During setting, amalgam shrinks, which results in micro­ leakage. But over a period of time, marginal seal improves

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as the corrosion products accumulate between restoration and the cavity walls.

Restorative Resins Placement of resin restoration is technique sensitive. Improper technique can result in faulty bond to tooth structure causing dentin hypersensitivity, recurrent disease and pulpal inflammation or necrosis. Etching with phosphoric acid dissolves the highly mineralized peritubular dentin leaving free collagen fibrils and opening dentinal tubules. The resin in the form of bonding agent has to infiltrate the exposed collagen mesh and seal the open dentinal tubules. If it does not do so then there is nanoleakage. Pulpal irritation from resin placement can be due to irritants such as unpolymerized monomer and polymerization shrinkage. The components of unpolymerized monomer may leach directly into pulp in case of deep cavities and cause chemical irritation. Polymerization shrinkage of composites induce internal stresses on dentin and create voids causing microleakage. This can be minimized by incremental placement and curing of composites and starting the restoration with flowable resins.

BIBLIOGRAPHY 1. Cohen S, Hargreaves KM. Pathways of Pulp, 9th edn. St. Louis: Mosby; 2006.pp.514-40. 2. Grossman L, Oliet S, Del Rio C. Endodontic Practice, 11th edn. Varghese publication, 1991.pp.59-65. 3. Ingle, Bakland Endodontics, 5th edn. BC Decker-Elsevier; 2002. pp.95-6. 4. Ingle J, Bakland L, Baumgartner J. Ingle’s Endodontics 6, 6th edn. BC Decker Inc, Hamilton; 2008.pp.468-87.

CHAPTER

5

Diseases of the Pulp and the Periradicular Tissues This chapter describes in detail the various diseases of the dental pulp and the periradicular tissues and their possible causes.

  You must know • What are the Possible Causes of Diseases of Dental Pulp? • How does the Pulp React to Different Direct and Indirect Stimuli and how is the Response unique? • How do we Classify the Diseases of Dental Pulp? • What are the Different Features of the Diseases of the Dental Pulp? • What are the Causes of Diseases of the Periradicular Tissues? • How do we Classify the Diseases of Periradicular Tissues? • What are the Different Features of the Diseases of Periradicular Tissues of Endodontic Origin? • What is the Pathogenesis of Primary Apical Periodontitis?

WHAT ARE THE POSSIBLE CAUSES OF DISEASES OF DENTAL PULP? Causes of Diseases of the Dental Pulp The various causes of diseases of the dental pulp are listed in Flow chart 4.1 ‘Noxious stimuli affecting dental pulp/ Causes of diseases of dental pulp’, in the previous chapter. They will be discussed in detail here.

Microbial/Bacterial Causes Coronal Ingress • Caries: Coronal caries is the most common means of ingress for infecting bacteria and/or their toxins into the dental pulp – Direct microbial invasion: - There are various portals of entry of micro­ organisms into the pulp. These have been explained in detail in Chapter 6: Endodontic Microbiology - Active carious lesion is composed of an outer infected layer and a deeper (underlying) affected

layer. The affected layer is the area which has been demineralized by acids produced by bacteria in the infected surface layer. - Reaction of dental pulp to dental caries has been explained in Chapter 4: The Pulpal Reactions to Caries and Dental Procedures. – Bacterial toxins before direct invasion: The pulp becomes inflamed from irritation by preceding bacterial toxins long before the bacteria reach the pulp to actually infect it. • Fractured crown: Microorganisms can invade the pulp following injury to tooth (Trauma) – Complete fracture: Accidental fracture generally does not devitalize the pulp at that instant. But untreated coronal fracture results in infection by oral bacteria gaining ready access to the pulp. Most commonly affected teeth are maxillary anterior teeth. Various dental traumatic injuries and their management have been discussed in detail in Chapter 24: Management of Dental Traumatic Injuries. – Incomplete fracture: Incomplete fracture of the crown (infraction) causes entry of bacteria into the pulp.

Diseases of the Pulp and the Periradicular Tissues

Pulp infection and associated pulpal inflammation depends on the extent of fracture (whether complete or incomplete) extending into pulp chamber or only through enamel. If it extends into pulp chamber, pulpitis develops. If only through enamel, pulp is merely hypersensitive to cold and mastication. • Nonfracture trauma: It was found by Grossman that the pulp canal infection can occur from trauma even without fracture of teeth. • Anomalous tract: Anomalous tooth development of tooth crown and the root can be a cause of bacterial invasion into the pulp. – Dens invaginatus: Most commonly found in maxillary lateral incisors. It can range from a slight lingual pit in the cingulum area to a frank anomalous tract apparent visually or radiographically. - Coronal dens in dente may involve all layers of enamel organ into the dental papilla. In such cases, pulp may be exposed and thus opens to bacterial invasion, inflammation and necrosis. There may be early development of periradicular lesions. - In radicular dens, there is a fold in HERS into developing tooth, producing enamel and dentin there. – Dens evaginatus: It has a tract to the pulp at its point of attachment. Found usually in mandibular premolars. – Radicular lingual groove or palatogingival groove: It is found primarily in maxillary lateral incisor. The defect starts in the region of the cingulum and proceeds apically and frequently towards the distal portion of the tooth for various distances along the surface of the root. Due to the nature of the groove, it is thought that the cementum formation is disturbed or even absent—No cementum, no attachment. In case of long groove, palatal abscess that forms extends to the apex.

Radicular Ingress • Caries: – Root caries is bacterial source of pulpal irritation - Less frequent occurrence than coronal caries - Cervical root caries occurs as a common sequel to gingival recession - Interproximal radicular caries may follow periodontal procedures if meticulous oral hygiene is not maintained. • Retrogenic infection: Pulp may become infected through apical foramen or lateral accessory canals associated with chronic periodontal pocket.

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– Periodontal pocket: It may extend to and surround the root apex. Such retrogenic infection is less common. Periodontal lesion causing Endodontic lesion is explained in Chapter 25: EndodonticPeriodontal Inter-relationships. – Periodontal abscess: Retrogenic pulp infection accompanying or immediately following an acute periodontal abscess, may be sometimes the cause of unexplained pulp necrosis. – Hematogenic blood borne microorganisms colonizing in the pulp: (Anachoresis) It refers to colonization or fixation of blood-borne microorganisms in the pulp. There is no enough evidence to explain the invasion of pulp by bacteria through blood. Systemic transient bacteremia may explain the unusual number of infected pulp canals following impact injury or fracture.

Physical Mechanical • Traumatic Injury to Teeth (Acute trauma) – Traumatic injury may directly or indirectly affect the dental pulp. – Trauma to teeth can occur in case of accidents, sports-related injury (Contact sports) or blow to the tooth. Various dental traumatic injuries, their effects on the pulp and their management have been discussed in Chapter 24: Management of Dental Traumatic Injuries. - Coronal fracture: Most pulp death following coronal fracture is due to bacterial invasion following the accident. - Radicular fracture: Accidental fracture of the root disrupts the pulp vascular supply and the injured coronal pulp can lose vitality. The apical radicular pulp tissue may remain vital. - Vascular stasis: In case of severe impact injury, the tooth may lose pulp vitality immediately. The pulp vessels get severed at the apical foramen causing ischemic infarction. Another response of pulp to trauma is formation of irritation dentin. - Luxation: Extrusive luxation, lateral luxation and intrusion result in pulp death nearly always. Pulp recovery may occur in case of immature young permanent tooth with wide, open apices. - Avulsion: Pulp necrosis occurs as a consequence of total avulsion of tooth. • Wasting diseases of teeth/noncarious destruction/ diseases of teeth/pathologic wear from attrition,

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abrasion: Wasting diseases such as attrition, abrasion cause Enamel to wear off and dentin gets exposed resulting in open dentinal tubules. If secondary dentin is deposited the tubules get occluded. Restorative fillings can be done to occlude these open dentinal tubules. In the absence of secondary dentin deposition and restoration, the pathologic wear continues, causing changes in pulp due to near exposure and direct exposure of pulp can result. • Cracked teeth: Cracked teeth may be in the form of: – Infractions of the crown – Actual fractures of crown and/or the root. Tooth infractions include: – Craze lines which involve only enamel. – Cuspal fracture, usually diagonal fracture involving enamel and running into dentin and may not directly involve the pulp. – ‘Cracked tooth syndrome’ is the term given to pain of apparently idiopathic origin that occurs due to incomplete fracture through the body of the tooth involving the pulp. Complete fractures include: – Split tooth: Complete vertical fracture of the crown and the root. – Vertical root fractures: usually associated with Endodontically treated teeth (nonvital teeth). Cracks and fractures occur in the vital teeth due to various causes such as: Weakening of teeth due to caries or restorative treatment procedures, hard chewing habits such as betel nut chewing, parafunctional habits such as bruxism. • Barometric changes: Changes in atmospheric pressure can affect the dental pulp. Low atmospheric pressure at higher altitudes over 10,000 feet may cause symptoms in a tooth that was chronically inflamed and symptomless at ground level. This is called barodontalgia. Generally pain is experienced in a recently restored tooth during low atmospheric pressure. Classification of barodontalgia given by Rauch:

Biomechanical Causes • Parafunctional habits such as clenching or bruxism may cause dentinal cracks with exposed dentinal tubules resulting in direct portal to subjacent pulp. • Occlusal loading causing tooth deformation occurs – Due to reduced occlusal isthmus while faciolingual extension of cavity preparation, loss of marginal ridges in case of mesio-occlusodistal (MOD) preparations causing 50% reduction in cuspal stiffness and fracture resistance. – Polymerization shrinkage of few composite resins can cause inward cuspal flexure and stresses on tooth. Dentin deformation causes flow of dentinal fluid activating nerve endings in odontoblast layer of tooth. Bacterial microleakage can occur through the gap at the restoration dentin interface that gets opened repeatedly during occlusal loading thus affecting the dental pulp.

Thermal Causes • Heat generated during cavity and crown preparation: Inadequate water coolant used during cavity and crown preparation can induce changes in pulp due to generation of heat. If only air is used as coolant at 2,00,000 rpm, it has been found that it takes just 11 seconds of continuous preparation at this speed to burn the pulp. • Frictional heat from polishing: During polishing of restorations, heat is generated. • Conduction of heat: Temperature changes may be conducted rapidly to the pulp when metallic fillings are placed in deep cavities without protective cement base. • Heat is generated from curing of resins during direct fabrication of provisional restoration. • Exothermic heat: Cements that set by exothermic reaction, liberate heat on setting causing atleast transient pulp injury.

Electrical Causes Dissimilar metallic fillings in the mouth when come in contact cause production of galvanic currents resulting in injury or pathologic changes in pulp. Such fillings are no longer done.

Iatral (Iatrogenic) • Cavity preparation – Heat of preparation: Heat generated during cavity preparation can cause pulp damage if adequate water coolant is not used.

Diseases of the Pulp and the Periradicular Tissues

Four basic factors in rotary instrumentation that cause temperature rise in the pulp, given by Swerdlow and Stanley, include: - Force applied by operator - Size, shape and condition of cutting tool - Revolutions per minute (RPM) - Duration of actual cutting time Lower speeds produce less thermal elevation than high speeds. – Depth of preparation: Deeper cavity preparations cause more extensive pulpal inflammation. – Dehydration: Excessive drying (desiccation) of the exposed dentin during cavity preparation can contribute to pulp inflammation. – Pulp horn extensions and pulp exposure: The close proximity of the pulp to the floor of the cavity preparation can expose the high pulp horns. Slow speed carbide burs can be used in areas of deep cavity preparation to avoid any traumatic mechanical exposure of the pulp. If possible, a layer of solid dentin (nonleathery) is allowed to remain as pulp cover. Also, it should be noted that use of airwater coolant is important in the areas where dentin is thinned and the pulp approached to prevent any pulpal damage. – Pin insertion: Earlier the pins that were used to support amalgam restorations or as a framework for building up badly broken down teeth for full coverage restorations, were found to cause pulp inflammation and pulpal death. In some cases, pins were inadvertently inserted directly into pulp or so close to that they acted as severe irritant. Such pins are no longer used with the advent of dentin bonding agents and adhesives. • Restoration – Insertion: After the insertion of gold foil or silver amalgam, severe hypersensitivity and pulpalgia may occur related to force of insertion or expansion of amalgam after insertion. Mild to severe hypersensitivity is found to occur after insertion of composite restoration, especially when total-etch technique using phosphoric acid is used or other causes such as over-drying of dentin, over-etching, faulty technique, moisture contamination, etc.) The use of self-etch bonding agents has been found to reduce the postoperative sensitivity to a great extent. – Fracture: Complete or incomplete fracture of posterior teeth have been found to occur after placement of silver amalgam or soft gold inlays or foil. Patient may have complaint of hypersensitivity or pulpalgia in case of undetected incomplete

•

•

•

• • •

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fractures. Patient gets relief when the cusp of the tooth finally fractures or the crown fractures horizontally. – Force of cementing: The tremendous hydraulic force exerted during cementation of an inlay or full crown in case of a vital tooth would drive the liquid towards the pulp causing pain while cementing. – Heat of polishing: Already discussed before in the thermal causes. Orthodontic movement: Use of mechanical separators for rapid separation of teeth or rapid orthodontic tooth movement can cause changes in the pulp. Also, some of the methods employed for removal of orthodontic brackets after treatment have the potential to injure the pulp. Periodontal curettage: During the periodontal curettage of a lesion that entirely extends around the apex of the root, the pulp vessels may be severed and the pulp may get devitalized. Electrosurgery: Inadvertent contact with metallic restorations during electrosurgery procedure may severely endanger the pulp and the periodontal structures. Laser burn: Higher intensity laser radiation can cause damage to the pulp. Periradicular curettage: During the periradicular curettage of an extensive bony lesion, the devitalization of the pulps of adjacent teeth has been found to occur. Intubation for general anesthesia: If an inflexible endotracheal tube is used during general anesthesia, heavy retraction against the mandibular incisors can cause their luxation.

Chemical Causes • Erosion caused due to acidity: Acidity (hydrogen ion concentration) causes erosion of enamel on labial or facial surface of teeth that eventually gets the dental pulp closer to irritating agents present in plaque and foods. • Restorative materials: – Acid etching of dentin with phosphoric acid: Acid etchants that contain phosphoric acid used for total etch technique of composite bonding are known to cause irritation of the pulp especially when prolonged dentinal etching is done opening up the dentinal tubules which are not completely occluded by application of bonding agent over the etched surface. – C h e m i ca l i r r i t at i o n o f pu l p o c c u r s f ro m unpolymerized monomer – Cavity liners, bases: Since the cavity liners and bases are applied directly on dentin, they should be

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nontoxic, nonirritating and cause no irreversible changes in the pulp and must have sufficient compressive strength so that it does not collapse or crush down under biting pressure. – Dentin bonding agents: If dentin is covered and protected with dentin bonding agents in case of Composite restorations, the problem of microleakage is avoided and the pulp is protected. • Disinfectants: Use of cavity disinfectants such as silver nitrate, phenol and sodium fluoride may adversely affect the pulp. • Dessicants: Use of dessicants such as alcohol, ether and others followed by air-drying with a blast of air may cause dessication, damaging the pulp.

HOW DO WE CLASSIFY THE DISEASES OF DENTAL PULP? I. Grossman has classified the diseases of dental pulp as:

Idiopathic • Aging: Regressive changes occur in the pulp tissue, such as decrease in number and size of cells and increase in the number of collagen fibers. There is deposition of secondary and tertiary dentin and pulp recedes with advancing age. • Resorption (internal and external): Various changes that can occur in case of pathologic tooth resorption have been explained in Chapter 30 Pathologic Tooth Resorption. • Systemic diseases such as sickle cell anemia, herpes zoster infection, etc. In case of sickle cell anemia, microcirculation of pulp is found to be affected resulting in pulp death. In herpes zoster infection, it is found that the virus may infect the pulp vasculature leading to infarction and pulp death.

HOW DOES THE PULP REACT TO DIFFERENT DIRECT AND INDIRECT STIMULI AND HOW IS THE RESPONSE UNIQUE? Pulp reacts to the above listed stimuli by inflammation. Inflammatory response of pulp is unique and differs from other connective tissues of the body as explained in the previous chapters.

II. Baume classified pulpal diseases based on clinical symptoms as follows:

Diseases of the Pulp and the Periradicular Tissues

III. Seltzer and Bender classified pulpal diseases according to histologic findings:

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In reversible pulpitis, peripheral A delta fiber stimulation occurs. Signs and symptoms: • Chronic or asymptomatic reversible pulpitis may be due to incipient caries and it gets resolved on removal of caries followed by appropriate restoration. • Acute or symptomatic reversible pulpitis may present with: – Sharp pain which is momentary – Responsive to cold food or beverage and/or cold air – Does not occur spontaneously – Does not continue when the etiologic factor is removed – Discomfort on biting on the recently placed restoration – Pain associated with an old restoration.

WHAT ARE THE DIFFERENT FEATURES OF THE DISEASES OF THE DENTAL PULP? Features of Pulp Inflammation (Pulpitis) Reversible Pulpitis Definition: • “Reversible pulpitis is a mild to moderate inflammatory condition of the pulp caused by noxious stimuli in which the pulp is capable of returning to the uninflamed state following removal of stimuli.” (Grossman’s Endodontic Practice, 11th edition, p.65) Etiology: Various etiologic factors include: (c2d2e2s2t2) • caries • defective restorations • exposed dentin • excessive dehydration of dentin caused by stream of compressed air or with alcohol or chloroform • chemical stimulus from irritation caused by silicate or self-cure acrylic resin • recent dental treatment • Decreased threshold stimulation for A-delta nerve fibers • Maxillary sinus disease causing generalized transient hyperemia of pulp of maxillary posterior teeth • trauma caused from a blow or due to disturbed occlusion or occlusal prematurity (high point) • thermal shock due to cavity preparation without adequate water coolant or using a dull bur or keeping the bur in contact with the tooth for long time or excessive heat produced during polishing of restoration.

Diagnosis: It is based on signs and symptoms and clinical diagnostic tests. • Clinical signs and symptoms such as sharp pain which is momentary (few seconds) that generally disappears on removal of stimulus such as cold, sweet or sour may point towards reversible pulpitis. • Diagnostic test such as cold thermal test can help locate and diagnose the involved tooth. • Radiographs generally show normal periodontal ligament status. Caries or deep restoration may be evident. Histopathologic findings: • Disruption of odontoblast layer • Dilated blood vessels • Extravasated edema fluid • Acute or chronic inflammatory cells Treatment: • Prevention of reversible pulpitis by: – Prevention of caries – Early detection of caries and restoration – Pulp protection base under restoration for deep cavities – Placing well-sealed restorations, to avoid marginal leakage – Proper contouring of restorations. – Adequate water coolants while cavity preparation or while polishing metallic restorations. • Palliative treatment includes: – Remove the restoration and replace it with a sedative cement such as Zinc oxide Eugenol.

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If pain persists or worsens, then extirpation of pulp is advised. – Reduce occlusal trauma if present.

Irreversible Pulpitis Definition: “Irreversible pulpitis is a persistent inflammatory condition of the pulp, symptomatic or asymptomatic, in which the pain persists for several minutes to hours, lingering even after the removal of the stimulus”. (Grossman’s Endodontic Practice, 11th Edition, p.67) Etiology: • Most common cause is bacteria affecting the pulp from caries. • Untreated reversible pulpitis progresses to irreversible pulpitis • Can have any of the other physical or chemical causes. • Thermal stimulation of A-delta nerve fibers causing lingering pain and stimulation of unmyelinated C-fibers causing spontaneous, dull aching pain. Signs and symptoms: • In case of symptomatic irreversible pulpitis: – In early stages: i. Intermittent or spontaneous pain. ii. Sudden temperature changes particularly cold stimuli elicit pain which lingers for long time even after the stimulus is removed. iii. Pain may be described as sharp, shooting, piercing which may be intermittent or continuous. iv. Pain may be localized or may get referred to adjacent teeth or other related structures such as temple, maxillary sinus, etc. v. Packing of food into the open cavity. vi. Pain with change in position or on lying down. – In later stages (Advanced) i. Pain may become severe described as boring, gnawing or throbbing ii. Intense pain on food lodgement in cavity or with stimulus iii. Severe pain affecting sleep that may be intolerable and not controlled in spite of all efforts of analgesia iv. Pain increased with hot water or food v. Exposed pulp may get covered with soft, leathery decay • In case of asymptomatic irreversible pulpitis: Deep caries may be evident clinically or radiographically but does not produce symptoms. If not treated, may become symptomatic or necrosis may occur.

Diagnosis: Based on clinical findings and diagnostic tests and radiographic examination: • On inspection, deep cavity or secondary caries at the margins of restoration may be seen or grayish leathery layer over the exposed pulp and surrounding dentin may be visible. • Probing over this superficial layer may not be painful. Deeper layers might elicit pain on probing. • Thermal tests elicit pain persisting even after removal of stimulus. • Radiographic appearance of periradicular bone may show minimal changes such as thickening of periodontal ligament. • Calcification in the form of pulp stones or calcification in canal may be evident on radiograph. Histopathology: • Chronic and acute inflammatory changes in the pulp are evident. • Congestion of postcapillary venules • Phagocytosis of PMN leukocytes

• Areas of microabscesses walled off by fibrous connective tissue, where calcific masses may be seen • Areas of necrotic tissue. Treatment: Endodontic treatment should be performed.

Chronic Hyperplastic Pulpitis Definition: “Chronic hyperplastic pulpitis or ‘pulp polyp’ is a productive pulpal inflammation due to an extensive carious exposure of a young pulp resulting from a long standing low grade irritation” (Grossman’s Endodontic Practice, 11th Edition, p. 70). Etiology: Etiologic factor is slowly progressing carious exposure of the pulp. Pulp polyp develops when there is: • Chronic low grade stimulus from mechanical irritation while chewing or bacterial irritation from caries in young pulp (Fig. 5.1 shows photograph showing pulp polyp in permanent mandibular first molar)

Diseases of the Pulp and the Periradicular Tissues

• Large open cavity (Figure 5.2 shows photograph of pulp polyp in deciduous molar with large open cavity). Signs and symptoms: • Usually asymptomatic • Sometimes if food bolus gets lodged in the open cavity causing pressure, discomfort may be felt by the patient • May bleed profusely if gets traumatized. Diagnosis: • Generally occurs in teeth of children and young adults • On inspection, fleshy, reddish pulpal mass filling most of the pulp chamber or cavity is seen. • Such polypoid tissue sometimes may extend beyond the confines of the tooth causing discomfort while biting.

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• Pulp polyp should be distinguished from gingival polyp – Pulp polyp is more sensitive than gingival polyp – Raise the polyp and trace its stalk to find its origin. Pulp polyp originates from pulp chamber • On probing, pulp polyp bleeds profusely due to rich network of blood vessels within it. • While performing diagnostic tests such as thermal and electric pulp tests, more current and more cold stimulus may be required to elicit pulp response. Histopathology: • Stratified squamous epithelium covering the surface of pulp polyp is seen. • Chronic inflammatory changes in pulp • Granulation tissue containing PMN neutrophils, lymphocytes and plasma cells is evident. Treatment: • Periodontal curette or spoon excavator is used to remove the hyperplastic pulpal mass completely to the level of orifices. • Bleeding is controlled. • Endodontic treatment is completed. Ulcerative/open form of chronic pulpitis: It is the chronic inflammation of the pulp in which there is formation of an abscess at the point of exposure due to caries and the abscess is surrounded by the granulomatous tissue. It is also known as pulpal granuloma.

Fig. 5.1  Pulp polyp in permanent mandibular first molar (Courtesy of Dr Manoj Ramugade)

Closed form of chronic pulpitis: It is the chronic inflammation of the pulp that may occur due to trauma, excessive orthodontic forces, any operative procedure or periodontal lesion. Caries may be absent.

Internal Resorption Definition: “Internal resorption is an idiopathic slow or fast progressive resorptive process occurring in the dentin of the pulp chamber or root canals of teeth”. (Grossman’s Endodontic Practice, 11th Edition, p. 71) Figure 5.3 shows diagrammatic representation of the internal resorption. The etiology, clinical features, diagnosis and different types of internal root resorption are discussed in detail in Chapter 30 Pathologic Tooth Resorption.

Features of Pulp Degeneration

Fig. 5.2  Pulp polyp in deciduous molar (Courtesy of Dr CR Suvarna)

Pulp degeneration occurs in: • Pulps of older people • May occur in pulps of younger people due to persistent mild irritation.

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• Calcific degeneration: – Calcific material replaces the pulp tissue in case of calcific degeneration in the form of pulp stones or denticles. – Calcification more commonly is seen in the pulp chamber since calcification proceeds from crown to root. – Types of calcification (see flow chart at the bottom of this page) – Pulp stone may either be in the body of pulp or attached to pulpal wall. Occurs as free, attached and embedded forms as shown in histologic section shown in Figure 5.4. True denticle is composed of dentin that is formed from detached odontoblasts or fragments of HERS. False denticle is formed by

deposition of concentric layers of calcified tissues with degenerated tissue structure as nidus. • Atrophic degeneration: – Seen in older people’s pulps on histopathologic examination. – The number of collagen fibers/unit area increases leading to fibrosis. – The number and size of cells decreases. These cells appear as shrunken solid particles in sea of dense fibers. – Pulp with atrophic degeneration is less sensitive than normal. • Fibrous degeneration: – Fibrous connective tissue replaces cellular elements of the pulp in this type of degeneration.

Fig. 5.3  Internal resorption

Fig. 5.4  Free, attached and embedded pulp stones

Diseases of the Pulp and the Periradicular Tissues

– It has been found that such degenerated pulp from the root canal has leathery fiber appearance. Atrophic and fibrous degeneration do not have a clinical diagnosis.

Features of Pulp Necrosis • Definition: Pulp necrosis is defined as: “Partial or total death of pulp following inflammation or a traumatic injury in which pulp gets destroyed before an inflammatory reaction takes place”. • Etiology: – Untreated symptomatic or asymptomatic irreversible pulpitis progresses to necrosis. – Trauma: Basically, injury to pulp by noxious stimuli such as bacterial, traumatic or chemical irritation leads to necrosis of pulp. • Types:

• Diagnosis: – History of severe pain lasting from few minutes to few hours, followed by cessation of pain completely. – In some patients, there can be slow death of pulp without any symptoms – Tooth may become symptomatic to percussion as the infection extends into PDL space – Tooth may exhibit hypersensitivity to heat or sometimes even to the warmth of oral cavity. Such pain is often relieved by application of cold. This helps in localization of necrotic tooth. – Diagnostic tests such as thermal and electric pulp tests:

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i. No response to cold test ii. No response to electric pulp test iii. Response may be elicited to prolonged application of heat due to remnants of pulpal fluid or gases expanding and extending into periapical region. – Radiographic changes : i. Large carious lesion may be seen. ii. Pulp stones in pulp chamber or some evidence of calcification in root canal may be seen. iii. Thickening of PDL space. • Histopathology: Pulp cavity shows necrotic pulp tissue, cellular debris and microorganisms. • Treatment: Endodontic treatment.

WHAT ARE THE CAUSES OF DISEASES OF THE PERIRADICULAR TISSUES?

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HOW DO WE CLASSIFY THE DISEASES OF PERIRADICULAR TISSUES?

WHAT ARE THE DIFFERENT FEATURES OF THE DISEASES OF PERIRADICULAR TISSUES OF ENDODONTIC ORIGIN?

A. Grossman has given the following classification:

Features of Normal Periradicular Tissues • Clinical: – No tenderness to pressure – No tenderness to percussion – No tenderness to palpation of mucosa overlying the periapical region – No swelling – No symptoms • Radiographic: (Fig. 5.5) – Intact lamina dura – Periodontal ligament space normal and of consistent width along the entire root – Periradicular bone with no rarefaction or condensation.

Features of Periradicular Diseases Acute Apical Periodontitis/Symptomatic Apical Periodontitis

B. WHO classification of diseases of periradicular tissues: Code number Category KO4.4 KO4.5 KO4.6 KO4.60 KO4.61 KO4.62 KO4.63 KO4.7 KO4.8 KO4.80 KO4.81 KO4.82

Acute apical periodontitis Chronic apical periodontitis (apical granuloma) Periapical abscess with sinus Periapical abscess with sinus to maxillary antrum Periapical abscess with sinus to nasal cavity Periapical abscess with sinus to oral cavity Periapical abscess with sinus to skin Periapical abscess without sinus Radicular cyst (apical periodontal cyst, periapical cyst) Apical and lateral cyst Residual cyst Inflammatory paradental cyst

C. Ingle has given the following classification: (see flow chart on next page)

• Definition: “Acute apical periodontitis is a painful inflammation of the periodontium as a result of trauma, irritation or infection through the root canal, regardless of whether the pulp is vital or nonvital”. (Grossman’s Endodontic Practice, 11th Edition, p.82) • Etiology: i. Bacterial: As a sequelae of pulpal disease, bacteria and their noxious products from inflamed or infected pulp may get diffused into periradicular area.

Fig. 5.5  Intraoral periapical radiograph showing normal periradicular tissues

Diseases of the Pulp and the Periradicular Tissues

ii. Trauma: – Occlusal trauma caused by abnormal occlusal contacts. – Occlusal prematurity of recently inserted restoration – Blow to the tooth – Wedging of foreign object in between teeth – Trauma from rapid orthodontic tooth movement iii. Iatrogenic: – Improper instrumentation forcing bacteria or debris inadvertently through the apical foramen – Forceful irrigation with irrigants such as sodium hypochlorite – Forcing irritating intracanal medicaments beyond the apex – Root perforation – Overinstrumentation – Over-extension or overfilling of obturating material extruding beyond the apex. • Signs and symptoms: i. Clinical: – May be associated with slight soreness in tooth, sometimes only when percussed.

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– There may be severe soreness in the tooth. – Tenderness to percussion is usually present. – Tooth may be extruded, making closure quite painful. – Tenderness to pressure – Mucosa overlying the root apex may not be tender. ii. Radiographic: – Slight widening of PDL space may be evident. – Small area of rarefaction may be seen especially in case of tooth undergoing Endodontic treatment. • Diagnosis: It is based on clinical and radiographic findings and history of a tooth under Endodontic treatment or of trauma or of a recently placed restoration. • Treatment: Etiologic factor should be determined and treatment provided accordingly. • Possible consequences of acute apical periodontitis: i. If the insult was of shor t duration such as overinstrumentation through healthy periapical region, symptoms usually subside and healing takes place. ii. In case of continuous and persistent irritation, the path would be:

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Chronic Apical Periodontitis/Asymptomatic Apical periodontitis: • Definition: “Asymptomatic apical periodontitis is a long-standing periapical inflammatory lesion in which there are minimum or no clinical symptoms but radiographically visible periapical bone resorption.” • Signs and symptoms: – Clinical: None or minimal symptoms such as slight discomfort on biting. – Radiographic: Periapical lesion may be evident. • Diagnosis: May be discovered on radiograph as an incidental finding. The radiologic appearance of lesion may be of any shape or size. There is widening of periodontal ligament space (Fig. 5.6). • Histopathologic findings: Histologically the radiolucent area may be in the form of granuloma or cyst. • Treatment: If extremely small lesion, it should be kept under observation. In case of larger lesion suggesting a granuloma or cyst with specific etiologic factor, Root canal treatment with enucleation or decompression may be required.

Persistent Apical Periodontitis It is the term used for the apical periodontitis that persists in the teeth even after Endodontic treatment. In spite of all efforts of performing Endodontic treatment well, due to complexity of root canal anatomy, instruments or irrigants and thus the obturation material may not reach few areas causing persistence of apical periodontitis. Also, few extraradicular factors that may contribute to persistent apical periodontitis, as given by Nair, include: • Periapical biofilms • Periapical scar tissue • Actinomyces infection • Cholesterol crystals • Foreign body reaction to gutta-percha.

Fig. 5.6  Radiograph showing apical periodontitis in relation to mandibular first molar with extensive caries involving the pulp (Courtesy of Dr Chetan Shah)

Acute Apical Abscess/Acute Alveolar Abscess • Definition: “An acute alveolar abscess is a localized collection of pus in the alveolar bone at the root apex of a tooth, following pulp necrosis, with extension of infection through the apical foramen into the periradicular tissues, accompanied by severe local and sometimes general reaction.” (Grossman’s Endodontic Practice,11th Edition, p. 78) Figure 5.7 shows diagrammatic representation of periapical abscess. • Etiology: i. Bacterial invasion from necrotic pulp tissue is the most common cause. ii. May be associated with history of trauma. iii. Chemical or mechanical irritation of pulp • Signs and symptoms: General: – General systemic reaction sometimes occurs – Patient may have mild to moderate fever accompanied by chills – Other symptoms such as headache, malaise, weakness – Patient may appear pale and irritable due to loss of sleep and absorption of septic products Local: (S4) – Initial signs and symptoms: Slight tenderness of tooth which gets relieved with slight pressure on extruded tooth pushing it back into the alveolus. Tender to percussion.

Diseases of the Pulp and the Periradicular Tissues

Fig. 5.7  Periapical abscess

– Later signs and symptoms: i. Severe spontaneous and throbbing pain due to pressure build up in the restricted periapical space. ii. Swelling of overlying soft tissue a. Begins with intraoral swelling b. Swelling then may become extensive resulting in cellulitis that distort patient’s appearance c. Swelling extends to the surrounding soft tissues: 1. In case of maxillary anterior tooth such as canine, swelling of the upper lip occurs, it may extend upto eyelid causing distortion of appearance. 2. In maxillary posterior teeth, huge swelling of cheek may occur 3. In mandibular anterior teeth, lower lip and chin may get swollen 4. In mandibular posterior teeth, swelling of cheek extending upto the ear may occur. iii. Suppuration or pus breaks to form: a. Sinus tract, that generally opens in the labial or buccal mucosa OR b. Spreads to overlying soft tissues taking the path of least resistance. This occurs due to perforation of overlying cortical plate and subsequently perforation of periosteum. In maxillary teeth since the labial alveolar plate is thinner than the palatal alveolar plate,

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suppuration usually occurs through labial or buccal mucosa except in case of maxillary lateral incisors and palatal root of maxillary molar in which suppuration occurs palatally due to close proximity of their roots to the palatal plate of the bone. In mandibular teeth also usually labial or buccal alveolar abscess occurs but lingual alveolar abscess may occur in case of mandibular molars due to the position of their roots in alveoli. – Radiographic findings: i. In case if the acute alveolar abscess is an exacerbation of a chronic lesion, a periapical radiolucency is generally evident on the radiograph. ii. Radiograph may not show destruction of alveolar bone in case of short duration acute alveolar abscess since the lesion is confined only to the medullary bone initially. Although radiograph may be helpful in determining the affected tooth showing carious involvement of pulp or thickened PDL space, etc. • Diagnosis: It is based on history, clinical and radiographic examination and diagnostic tests. The affected tooth is necrotic and does not respond to electric pulp test and thermal tests. Location of swelling may help determining the affected tooth. Mobility and extrusion of tooth may be evident. • Histopathologic findings: Infiltration of PMN leukocytes and accumulation of inflammatory exudate cause distension of periodontal ligament and thereby causing extrusion of tooth. Then, there is separation of periodontal fibers causing mobility of tooth. • Treatment: – Control the acute systemic reaction if present. – Administration of antibiotics. – In case of localized swelling, incision and drainage should be established. – Concomitantly, establishing drainage through the root canal relieves the severe symptoms. Swelling may remain for sometime before it gradually subsides. – In case of hyperocclusion, relieve the tooth out of occlusion. – Nonsteroidal anti-inflammatory drugs can be given to control pain. – In the subsequent visit, thorough cleaning and shaping of root canals is performed.

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Chronic Apical Abscess/Chronic Alveolar Abscess • Definition: “Chronic alveolar abscess is a long-standing low-grade infection of the periradicular bone. The source of infection is in the root canal.” (Grossman, 11th edition, p.85) It is also called suppurative apical periodontitis as an exudate is formed due to egress of irritants from root canal system into periradicular area. • Etiology: – An acute alveolar abscess may become chronic apical abscess OR – Necrosis of pulp may result in low-grade infection extending into periradicular bone. • Signs and symptoms: i. Generally, a ‘sinus tract’ is detected, which is considered a hallmark sign of chronic alveolar abscess. Although intraoral sinus tract is common, sometimes it may open through skin of face. ii. There is usually no pain or mild pain may be present. iii. Sinus tract causes continual drainage of the periradicular lesion into the oral cavity and it thus prevents swelling or an acute exacerbation of the lesion. iv. Sometimes a large carious lesion with open cavity may be present causing drainage by way of root canal. • Radiographic findings: Radiograph mostly shows periapical radiolucency (Figure 5.8 shows a radiograph showing periapical radiolucency in maxillary right lateral incisor tooth). • Diagnosis: – In case of sinus tract, a gutta-percha point can be introduced into the tract and a radiograph taken to find the source of infection. Figure 5.9 shows the photograph of mandibular molar where guttapercha point has been used to trace the source of infection. Figure 5.10 shows the radiograph of the same case. – Tooth generally does not respond to the diagnostic tests such as thermal and electric pulp vitality tests. – Necrotic tooth may be discolored in few cases. – Radiograph may show diffuse area of rarefaction. • Histopathologic findings: – With the invasion of microorganisms and their toxins into the periradicular area, some of the periodontal ligament fibers at the root apex are detached or lost and the apical periodontal ligament gets destroyed subsequently. – In the periradicular lesion, PMN leukocytes are found in the center and the lymphocytes and plasma cells at the periphery.

Fig. 5.8  Radiograph showing periapical radiolucency suggestive of abscess in relation to maxillary right lateral incisor tooth (Courtesy of Dr Mansi Shah, Dentoview: Advanced dental imaging center)

Fig. 5.9  Gutta-percha point/cone being used to trace the source of infection (Courtesy of Dr Manoj Ramugade)

Fig. 5.10  Radiograph showing gutta-percha point/cone used for tracing the sinus tract shows that the source of infection is in the distal root canal of mandibular second molar (Courtesy of Dr Manoj Ramugade)

Diseases of the Pulp and the Periradicular Tissues

• Treatment: – Root canal treatment to eliminate infection. – Sinus tract does not require any special treatment. It closes and disappears once the root canal is properly cleaned and shaped.

Acute Exacerbation of Chronic Lesion/Phoenix Abscess Phoenix abscess is discussed in Chapter 19: ‘Endodontic Emergencies and Mid-treatment Flare-ups’.

Periapical Granuloma • Definition: “Periapical granuloma is a chronic, lowgrade defensive reaction of the alveolar bone occurring as a granulomatous tissue growth continuous with the periodontal ligament in response to continued mild irritation caused by the diffusion of bacteria and bacterial toxins from the root canal into the surrounding periradicular tissues through the apical and lateral foramina.” (Endodontic Practice, Grossman, 11th Edition, p.89) Figure 5.11 shows diagrammatic representation of periapical granuloma. • Etiology:

Fig. 5.11  Periapical granuloma

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• Signs and symptoms: – Usually asymptomatic – If it undergoes suppuration, there may be symptoms – Radiographic findings: Loss of continuity of lamina dura and well-defined area of rarefaction varying in size from few millimeters to a centimeter or even larger at the apex of the root. • Diagnosis: – Usually diagnosed on routine radiographic examination (Fig. 5.12) – Exact diagnosis to be named as ‘Periapical granuloma’ can be made only after microscopic examination. – Tooth does not respond to thermal and electric pulp tests. • Histopathologic findings: The alveolar bone and periodontal ligament are replaced by granulomatous tissue showing the following features: – Inflammatory lesion consisting of macrophages, lymphocytes and plasma cells in the loose connective tissue forming the inner or central portion. – Shows collagenous connective tissue forming the capsule of the lesion which is continuous with the periodontal ligament. – Epithelial cell proliferation is a common feature. – There are abundant capillaries and blood vessels along with numerous fibroblasts and connective tissue fibers. – Clusters of epithelial cells called cell rests of Malassez derived from Hertwig’s epithelial root sheath (HERS) are also found.

Fig. 5.12  Radiograph showing periapical radiolucency likely to be a periapical granuloma in relation to maxillary right central incisor tooth (Courtesy of Dr Mansi Shah, Dentoview: Advanced dental imaging center)

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• Treatment: – Root canal treatment. – Once the source of chronic irritation is removed, there is resorption of granulomatous tissue and repair of the periradicular bone.

Radicular Cyst Also called periapical cyst (Figure 5.13 shows diagrammatic representation of periapical cyst). • Etiology:

• Signs and symptoms: – Most common site for radicular cyst is anterior maxilla area. In case of radicular cyst related to maxillary lateral incisor, palatal expansion is usually seen. – Usually the tooth with radicular cyst is discolored and nonvital. It may show fracture or failing Endodontic treatment. – Asymptomatic when small in size. – When the cyst becomes larger, it may cause swelling, increased pressure causing mobility of teeth, pain, etc.

Fig. 5.13  Periapical cyst

– Radiographic findings: Loss of continuity of lamina dura and well-defined round, ovoid or pear-shaped radiolucency at the apex of the tooth which is larger than the granuloma and may involve adjacent teeth (Figure 5.14). • Diagnosis – Generally from radiographic examination – Diagnostic tests such as thermal and electric pulp tests are negative. – CBCT is recent diagnostic tool that may help to detect periapical cyst easily and clearly. Figure 5.15 shows a CBCT image of a tooth with periapical pathology most likely to be radicular cyst. • Histopathologic findings: An epithelium-lined cavity containing fluid or semisolid material commonly surrounded by dense connective tissue. Cystic cavity is lined by stratified squamous epithelium derived from epithelial cell rests of Malassez.

• Treatment: Root canal treatment with or without surgical enucleation of radicular cyst.

Fig. 5.14  Radiograph showing periapical radiolucency likely to be a periapical cyst in relation to maxillary right central incisor tooth (Courtesy of Dr Mansi Shah, Dentoview: Advanced dental imaging center)

Diseases of the Pulp and the Periradicular Tissues

Fig. 5.15  CBCT image showing tooth with a pathology likely to be radicular cyst (Courtesy of Dr Mansi Shah, Dentoview: Advanced dental imaging center)

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Fig. 5.16  Radiograph showing condensing osteitis in relation to mandibular second molar tooth (Courtesy of Dr Mansi Shah, Dentoview: Advanced dental imaging center)

It is generally recommended to perform root canal treatment alone and if the lesion fails to resolve then surgical treatment (Apicoectomy) may be indicated.

Condensing Osteitis: (Or Focal Sclerosing Osteomyelitis) • Definition: “Condensing osteitis is a diffuse radiopaque lesion of the periradicular area that occurs in response to a low-grade inflammatory stimulus from the root canal.” • Etiology: Chronic mild irritation from long-standing pulpal pathosis causes stimulation of osteoblastic activity in the alveolar bone. • Signs and symptoms: Asymptomatic, diagnosed only on radiographic examination. • Radiographic findings: Overproduction of bone in the periapical area around the apices of teeth with long standing pulpal pathosis. Most commonly involved teeth are apices of mandibular premolars and molars (Figs 5.16 and 5.17). • Diagnosis: From radiographs. Appears as localized area of radiopacity surrounding the affected root. It is dense area due to overproduced bone with reduced trabecular pattern. • Histopathologic findings: Area of dense bone is seen with the trabecular borders lined with osteoblast cells. • Treatment: Root canal treatment. May or may not respond to root canal treatment.

Fig. 5.17  Radiograph showing condensing osteitis in relation to mandibular first molar tooth (Courtesy of Dr Mansi Shah, Dentoview: Advanced dental imaging center)

External Root Resorption • Definition: “External resorption is a lytic process occurring in the cementum or cementum and dentin of the roots of the teeth.” (Grossman’s Endodontic Practice, 11th Edition, p.98) Figure 5.18 shows diagrammatic representation of external root resorption. • Types: External root resorption

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• Etiology: Not exactly known. – Suspected causes — Inflammation of the periradicular area caused due to: a. Trauma b. Injury to external root surface c. Excessive forces caused by orthodontic treatment d. Periapical granuloma or cyst applying pressure on the root e. Overinstrumentation during root canal treatment

Fig. 5.18  External root resorption

f. Impaction of adjacent tooth g. Central jaw tumors h. Systemic diseases – When the cause is not evident, it is termed as idiopathic resorption • Signs and symptoms: Asymptomatic, diagnosed only on radiographic examination. Only when the root is completely resorbed, mobility of tooth may occur. Sometimes in the same tooth, both external and internal root resorption may occur. When external root resorption extends into the crown, it appears as “pink tooth”(Internal resorption) • Radiographic findings: – Radiographic appearance of external root resorption is concave or ragged areas on root surface or blunting of apex which is sometimes difficult to detect on radiographs. CBCT scans can show these changes caused by external resorption quite well. Figure 5.19 shows CBCT image of tooth in which external root resorption has caused blunting of apex of root. – In case of replacement resorption or ankylosis: Resorbed root with no PDL space and bone replacing the defects is seen. – In case of inflammatory resorption caused due to pressure of growing granuloma, cyst or tumor, an area of root resorption adjacent to area of radiolucency may be seen. All these different types of resorption have been explained in detail in Chapter 30: Pathologic Tooth Resorption.

Fig. 5.19  CBCT image of tooth in which external resorption has caused blunting of apex of root (Courtesy of Dr Mansi Shah, Dentoview: Advanced dental imaging center)

Diseases of the Pulp and the Periradicular Tissues

• Diagnosis: From radiographs. – It is difficult to detect external root resorption on radiograph especially the small areas of surface resorption of cementum which can be detected only histologically. Only when significant amount of root substance is removed, it can cause enough contrast to be detected on radiograph. – Resorptive defect on the mesial or distal aspect of the root may be detected on the radiograph – Bone adjacent to root resorption also gets affected by inflammation causing bone resorption which is more easily detected on radiograph because bone is not as radiodense as the root. • Histopathologic findings: – Small areas of cementum resorption replaced by connective tissue or repaired by new cementum – Large areas of resorption replaced by osseous tissue – “Scooped out” areas of resorption replaced by inflammatory or neoplastic tissues. • Differential diagnosis: Internal root resorption and other types of Root Resorption discussed in Chapter 30: Pathologic Tooth Resorption. • Treatment: – Treatment varies with etiologic factor : a. When caused by extension of pulpal disease into supporting tissues, root canal treatment will stop the resorptive process. b. When caused by excessive forces from orthodontic appliances, the resorptive process can be stopped by reducing those forces c. When caused in case of replantation, preparation of root canal and obturation with calcium hydroxide may stop the resorptive process Prognosis of external root resorption is guarded as although the resorptive process may stop once the etiologic factor is removed but tooth may become weak and may not be able to sustain functional forces.

Periradicular Diseases of Nonendodontic Origin • Periradicular diseases may originate in the remnants of odontogenic epithelium or may be manifestations of systemic disease such as multiple neurofibromatosis or may occur in case of periodontal disease. • Few examples of periradicular disease of NonEndodontic origin include: a. Periapical cemental dysplasia b. Cementoma

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c. Cementoblastoma d. Odontogenic cysts e. Central giant cell granuloma f. Metastatic malignant tumors or ameloblastoma • The periradicular diseases of nonendodontic origin may resemble the sequelae of pulpal diseases in periradicular area clinically and radiographically. They should be differentiated from them to avoid errors in treatment. The main distinguishing point is that the in case of lesions of Endodontic origin, the pulp is irreversibly diseased or may be necrotic whereas in case of periradicular diseases of nonendodontic origin, the pulp is usually vital. • In case of metastatic malignant tumors or ameloblastoma, aggressive signs such as excessive bone loss, mobility of teeth, loss of pulp vitality may be evident.

WHAT IS THE PATHOGENESIS OF PRIMARY APICAL PERIODONTITIS? • Persistent microbial infection of the root canal system results in the inflammatory disorder of the periradicular tissues called primary apical periodontitis. • Apical periodontitis is the body’s defense response to the destruction of the pulpal tissue and microbial infection of the root canal system which minimizes the spread of the infection but it cannot eliminate microbes present in the necrotic root canal as protected biofilms. Thus, apical periodontitis is not self-healing, its resolution requires nonsurgical or sometimes surgical Endodontic therapy. • The infected and necrotic root canal system consists of microorganisms in the following forms: – Planktonic cells suspended in fluid phase of canal, – Sessile biofilms (discussed in detail in the next chapter) – Aggregates and coaggregates. • Related Periradicular pathologies: 1. Acute apical periodontitis is an acute inflammation of the periodontium of Endodontic origin. Distinct focus of neutrophils is present in the lesion. Types of acute apical periodontitis: A. Primary or initial acute apical periodontitis: It is the inflammation of healthy periodontium in response to irritants and is of short duration. B. Secondary or exacerbating apical periodontitis: It is an acute response in an already existing chronic periodontal lesion. It is also called periapical flare-up, or phoenix abscess.

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2. Established chronic apical periodontitis is a long standing inflammation of periodontium of Endodontic origin. Granulomatous tissue infiltrated with lymphocytes, plasma cells and macrophages is seen. 3. Periapical true cyst is an apical inflammatory cyst that consists of pathologic cavity completely enclosed in an epithelial lining. There is no communication to the root canal. 4. Periapical pocket cyst is an apical inflammatory cyst that consists of a sac-like, epithelium lined cavity. There is communication to the root canal.



Root canal therapy aims at prevention or treatment of apical periodontitis.

BIBLIOGRAPHY 1. Cohen S, Hargreaves KM. Pathways of Pulp, 9th edn. St. Louis: Mosby; 2006.pp.40-58, 541-79. 2. Grossman L, Oliet S, Del Rio C. Endodontic Practice, 11th edn. Varghese publication; 1991.pp.59-101. 3. Ingle J, Bakland L, Baumgartner J. Ingle’s Endodontics, 6th edn. BC Decker Inc, Hamilton; 2008.pp.468-487, 494-513. 4. Ingle, Bakland Endodontics, 5th edn. BC Decker, Elsevier; 2002. pp.95-149.

CHAPTER

6

Endodontic Microbiology

This chapter tells you about the role of microorganisms in the pathogenesis of Endodontic disease and the techniques for identification and control of Endodontic infections.   You must know • What is the Basis of Focal Infection Theory and Why is it Totally Rejected Today? • What are the Pathways or Portals of Entry of Microorganisms in the Pulp? • What is the Microbial Flora of Root Canal? • What are the Types of Endodontic Infections? • What is the Role of Microbial Virulence and Host Response in the Pathogenesis of Disease? • What are the Methods for Detection, Identification and Examination of Microbes? • What is the Biofilm and what is its Significance in Endodontics?

WHAT IS THE BASIS OF FOCAL INFECTION THEORY AND WHY IS IT TOTALLY REJECTED TODAY? Supporters of this theory believed that pulpless and Endodontically treated teeth may leak bacteria or toxins or both into the body, causing illnesses such as arthritis, intestinal disorders, anemias and other diseases of the various systems of the body. With the expansion of this theory, millions of teeth were needlessly extracted to cure various chronic illnesses.

Origin of Focal Infection Theory • In 1890, WD Miller proposed that pulpal and periapical disease was associated with the presence of bacteria. • In 1904, Billings defined ‘focus of infection’ as ‘circumscribed area of tissue infected with pathogenic organisms’ and described the positive correlation between oral disease and bacterial endocarditis. • In 1904, Rosenow, a student of Billings, described the ‘theory of focal infection’ which stated that localized or generalized infection is caused by bacteria traveling through the bloodstream from a distant focus of infection.

• In 1910, William Hunter, in a lecture on role of sepsis and antisepsis in medicine, condemned the practice of dentistry and stated that nonvital pulps and Endodontically treated teeth were the cause of many chronic illnesses. This presentation inadvertently affected the practice of root canal therapy and unwarranted extraction of nonvital and Endodontically treated teeth continued for approximately 20 years. Other details of the focal infection theory are given in Chapter 8 Rationale of Endodontic Therapy.

Rejection of Focal Infection Theory In 1930, an editorial published in dental cosmos, rejected the focal infection theory and called for a return of constructive rather than destructive dental treatment rationale. Numerous studies were conducted to cure chronic illness, but in nearly all cases, the disease returned and the patient now faced the additional difficulty of living with mutilated dentitions.

Conclusion On the basis of various clinical and scientific studies, both medical and dental professions concluded that there is no relationship between Endodontically treated teeth or

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nonvital pulps and the degenerative diseases implicated in the theory of focal infection. Also, many epidemiologic and biologic studies dem­ onstrated that Endodontic therapy is safe and results  in saving the teeth without endangering systemic health.

WHAT ARE THE PATHWAYS OR PORTALS OF ENTRY OF MICROORGANISMS IN THE PULP? Microorganisms can enter the pulp through different pathways as listed in Figure 6.1. (Remember the Mnemonic:

DRAPE—Dentinal tubules, Restorations, Anachoresis, Periodontal tissues, Exposure of pulp).

WHAT IS THE MICROBIAL FLORA OF ROOT CANAL? Colonization is the establishment of microbes in a host when biochemical and physical conditions are adequate for growth. Normal microbial flora is the result of permanent colonization of microbes in a symbiotic relationship that produces beneficial results.

Fig. 6.1  Portals of entry of microorganisms in the pulp

Endodontic Microbiology

Fig. 6.2  Diagram showing dental caries: (a) Dental caries; (b) Infected pulp; (c) Periapical pathology

A

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Fig. 6.4  Diagram showing pulp exposure due to trauma: (a) PDL widening; (b) Traumatic exposure of pulp; (c) Angle fracture of maxillary central incisor

B

Figs 6.3A and B  Diagram showing exposed dentinal tubules as pathway to pulp: (A) Normal tooth; (B) (a) Attrition; (b) Exposed dentinal tubules; (c) Abrasion

Fig. 6.5  Diagram showing pulp exposure during restorative procedures. Pulp exposure in a mesially inclined mandibular molar during tooth preparation for receiving fixed partial denture indicated by arrow

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Fig. 6.6  Diagram showing pathways of pulp through periodontal tissues: (a) Lateral canal; (b) Furcation canal; (c) Periodontal pocket; (d)  Accessory canals; (e) Apical foramen

Fig. 6.8  Radiograph showing recurrent caries at the margins of restoration causing pulpal involvement and periradicular infection in mandibular first molar (Courtesy of Dr Chetan Shah)

Flow chart 6.1  Microorganisms that may be present in an infected root canal

Fig. 6.7  Diagram showing leakage underneath the restoration. Marginal leakage under restoration may cause pulpal infection

Root canal flora predominantly consists of aerobic and facultative anaerobic microorganisms. Most of them are gram-positive but few gram-negative and obligate anaerobes are also found. • Endodontic infections are polymicrobial in nature. • The number of colony forming units (CFU) is 100 to 10 to the power 8. • Classification of microorganisms present in an infected root canal are listed in Flow charts 6.1, 6.2 and 6.3. Which bacteria will predominate is determined by: i. Tissue fluid ii. Necrotic pulp tissue

iii. Low oxygen tension iv. Bacterial byproducts.

WHICH ARE THE TYPES OF ENDODONTIC INFECTIONS? Endodontic infections can be: I. Primary II. Secondary III. Persistent I. Primary root canal infections generally consist of anaerobic gram-negative bacteria such as:

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Flow chart 6.2  Different bacteria in an infected root canal

II. Secondary root canal infections may be caused by microorganisms that were not present during primary infections but introduced during treatment between appointments or after Endodontic treatment. Commonly found microorganisms in case of secondary Endodontic infections include: – Enterococcus – Staphylococcus – Streptococcus – Actinomyces – Pseudomonas – Candida sp. – Propionibacterium Improper coronal seal causing leakage has been implicated as an important cause of post-treatment apical periodontitis.

Flow chart 6.3  Classification according to Gram stain technique

III. Persistent root canal infections may be caused by bacteria present within the canal at the time of obturation that resist filling procedures and materials to survive even in changed environment maintaining the periradicular inflammation. This is most important cause of Endodontic failure. Enterococcus faecalis is predominant microbe in canals undergoing retreatment in cases of failed Endodontic therapy and canals with persistent infections. Also Streptococcus faecalis, Actinomyces sp., Candida sp. may be found in such cases.

– Porphyromonas endodontalis, Porphyromonas gingivalis – Prevotella – Peptococci – Peptostreptococci – Fusobacterium – Eubacterium – Actinomyces. All these species are black-pigmented and have been associated with clinical signs and symptoms. • Bacteroides melanogenicus, an important causative agent can be classified into two groups: – Saccharolytic species (Prevotella genus) – Asaccharolytic species (Porphyromonas genus) • Treponema denticola, a recognized periodontal pathogen, has been found in infected root canals and abscesses. • Three pathogens that form red complex: – T. denticola – T. forsythia – T. gingivalis have also been found in Endodontic infections.

Enterococcus faecalis: E. faecalis is a gram-positive cocci and a facultative anaerobe which is normally present in the intestine. It may be found in the oral cavity and gingival sulcus. E. faecalis has following unique features due to which it can survive even in treated root canals (Fig. 6.9 mind-map):

Fig. 6.9  Mind-map to remember unique features of E. faecalis that make it exceptional survivor in root canal

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• It can persist in spite of poor nutrient environment in Endodontically treated teeth. • It survives even in the presence of root canal irrigant such as sodium hypochlorite and intracanal medicament such as calcium hydroxide. • It tends to invade and metabolize fluid within dentinal tubules and adheres to collagen in the presence of human serum. • It endures prolonged periods of starvation and utilizes tissue fluid from periodontal ligament. • It is known to convert into a Viable But Non-Cultivable state (VBNC) • It can survive in adverse conditions such as low pH, high salinity and high temperatures. • It can acquire gene-coding antibiotic resistance

in combination with natural resistance to various antimicrobial agents. Figure 6.10 shows a mind-map to remember all the microbial flora of root canal and types of Endodontic infections and Figure 6.11 summarizes all points of microbiology of infected root canal.

WHAT IS THE ROLE OF MICROBIAL VIRULENCE AND HOST RESPONSE IN THE PATHOGENESIS OF DISEASE? The ability of microorganisms to produce a disease is called pathogenicity. The degree of pathogenicity caused by microbes is referred to as virulence.

Fig. 6.10  Mind-map to remember types of Endodontic infections

Endodontic Microbiology

The pathogenic response includes damage caused by the host in response to the microbes. Host’s response includes: • Nonspecific inflammatory reaction • Specific immunologic reaction The pathogenic responses are associated with: a. Microorganisms (Bacterial virulence factors given in Figure  6.12) b. Associated host responses (Flow chart 6.5).

Bacterial Virulence Factors (Remember the short sentence: PLEASE Care For— Polyamines, Lipopolysaccharides, Enzymes, Ammonia, Short chain fatty acids, Extracellular vesicles, Capsule, Fimbriae (Fig.  6.12).

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WHAT ARE THE METHODS FOR DETECTION, IDENTIFICATION AND EXAMINATION OF MICROBES FROM A ROOT CANAL? Flow chart 6.6 lists the methods for detection, identification and examination of microbes.

Culture Methods Technique • Isolate the tooth with rubber dam. • Remove the dressing from root canal of previous visit. • Insert a sterile absorbent point into the canal and wipe the canal to remove any intracanal medicament. • Take a fresh, sterile absorbent point till the apex or slightly beyond to absorb as much periapical exudates and microorganisms from the root canal as possible.

Fig. 6.11  Mind-map to remember all points of microbiology of infected root canal

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Fig. 6.12  Bacterial virulence factors



Let the absorbent point remain there for at least one minute. • The absorbent point is removed with the sterilized cotton pliers and is put into the culture medium. • The sample is sent for laboratory examination. Gramstaining demonstrates which type of microorganisms predominate. • Culturing anaerobic microorganisms from samples obtained from root canal and periapical tissue require special equipment and temperature controlled, oxygenfree medium. Using an aseptic technique, sterile needle of Luer Lok syringe is inserted into periradicular space. Aspirate is

collected in oxygen free, anaport vial and transported to any anaerobic culturing depot for examination.

Advantages • It allows identification of a great variety of microbial species in a sample. • Helps in determination of antimicrobial susceptibility for appropriate treatment.

Disadvantages • They have low sensitivity and specificity • May give false-negative results

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Flow chart 6.5  Host response to the microbes

Flow chart 6.6  Methods for detection, identification and examination of microbes

• Time-consuming • Transport of sample to the laboratory is required. For anaerobic bacteria, sampling and transportation will have to be done in carefully controlled anaerobic condition.

2. Polymerase chain reaction method: – It involves in vitro replication of DNA referred to as genetic xeroxing – Standard PCR procedure is called Single PCR – Variation in standard PCR: Nested PCR, Reverse transcriptase (RT)-PCR Multiplex PCR, Real-time PCR – PCR has excellent detection limits – Can be used to investigate microbial diversity in a given environment – PCR techonology can be used for clonal analysis of microorganisms. In the past, with culture sensitivity, microorganisms were detected and specific drugs were used against them such as PBSC/PBSN paste. P – Penicillin (Against Gr +ve) B – Bacitracin (Against penicillin resistant organisms) S – Streptomycin (Against Gr –ve) C – Caprylate sodium (Against yeast and fungi) These drugs were in powder form carried in a vehicle to form a paste. Sterility of root canal or reduction in number of micro­ organisms in root canal is detemined by bacteriological examination before obturating a canal to ensure that no evidence of microbial growth is present. In difficult cases that do not respond to routine Endodontic treatment, microbiologic examination has to be done. If culture techniques yield a negative result then the newly introduced molecular techniques may detect the specific microbes in Endodontic infections, that were previously unidentified or uncultivable. A mind-map showing methods for detection and identi­ fication and examination of microbes (Fig. 6.13).

Molecular Diagnostic Methods These methods have been recently introduced for precise identification of Endodontic pathogens based on the microbial genome and there is then no need for cultivation.

Advantages • They have greater sensitivity and specificity • They can detect both cultivable and uncultivable microbial species and strains • Less time-consuming • There is no need for cultivation and the microbial species can be detected directly in clinical samples.

Disadvantages • Expensive • Can be laborious. 1. DNA—DNA hybridization method: This method uses DNA probes that may target whole genomic DNA or individual genes such as 16S rDNA. Useful for large-scale epidemiologic research as it allows simultaneous determination of multitude of bacterial species in single or multiple clinical samples.

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WHAT IS THE BIOFILM AND WHAT IS ITS SIGNIFICANCE IN ENDODONTICS? Biofilm Biofilm is a mode of microbial growth where dynamic communities of interacting sessile cells are attached to each other and to a solid substratum irreversibly and embedded in a self-made matrix of extracellular polymeric substances (EPS). Four basic criteria that determine a microbial biofilm, as given by Ingle, include:

1. 2. 3. 4.

Autopoiesis (ability to self-organize) Homeostasis (resist environmental perturbations) Synergy (more effective in association than in isolation) Communality (respond to environmental changes as a unit rather than single individuals) – Dental plaque can be considered as typical example of a biofilm – Bacterial cells: Planktonic—Free floating bacterial cells in an aqueous environment Biofilm—Sessile bacterial cells attached to a solid surface.

Fig. 6.13  A mind-map to remember all points of methods for detection, identification and examination of microbes

Endodontic Microbiology

The sessile microorganisms protected in biofilms are more than 1000 times resistant to antimicrobial agents as the same organisms in planktonic form. The phenotype of biofilm bacteria is distinct from that of planktonic bacteria. Bacterial cells within the biofilm have altered phenotypic properties that protect them from: i. Antimicrobials ii. Environmental stresses iii. Bacteriophages iv. Phagocytic amoebae Since biofilms are resistant to both host defense mechanisms and antibiotic therapy, they are responsible for most chronic infections and recalcitrant infections in human beings. • Common biofilms found in oral cavity are protective in nature and essential for maintenance of oral health as they inhibit the adherence of pathogenic microorganisms through colonization resistance. But any environmental change favoring colonization by pathogenic bacteria causing ecological shift and decline in host defense mechanism due to disease will cause harmless commensals to become opportunistic patho­gens. Type and availability of nutrients and oxygen tension determine the nature of bacteria associated with a biofilm. All common oral diseases—Dental caries, Gingivitis, Periodontitis, apical periodontitis are biofilmmediated diseases. • Ultrastructure of Biofilm (Fig 6.14): Microcolonies or cell clusters formed by surface adherent bacterial cells, surrounded by Glycocalyx matrix made of Extracellular

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Polymeric Substances (EPS) that anchors bacterial cell to substrate. About 85% by volume of Biofilm is matrix material and 15% is cells. A fresh biofilm consists of polysaccharides, proteins, nucleic acids and salts embedded in extracellular matrix. Matured biofilm structure and composition varies according to environmental conditions such as: growth conditions, nutritional availability, etc. A viable, fully hydrated mature biofilm appears as tower or mushroom shaped structure adherent to the substrate. The primitive circulatory system in the biofilm is water channels that intersect the structure of biofilm and form connections between microcolonies that facilitate exchange of materials between bacterial cells and bulk fluid. This is important in coordinating functions of biofilm community. • Development of Biofilm: Biofilms tend to form when there is flow of fluid, microorganisms and a solid surface. Figure 6.15 shows the schematic representation of stages of biofilm formation. Stage 1: Formation of conditioning layer: The inorganic and organic molecules get adsorbed to the solid surface to form conditioning layer, e.g. Saliva pellicle is the conditioning layer on tooth during dental plaque formation. Stage 2: Adhesion of microbial cells to the conditioning layer. Stage 3: Bacterial growth and biofilm expansion. Micro­ colonies are formed. Two microbial interactions that occur at cellular level include: i. Coadhesion which is recognition between suspended cell and cell already attached to substratum (Fig. 6.16B)

Fig. 6.14  Schematic representation of ultrastructure of mature biofilm (N-Nutrients; M-Metabolic products; S-Signal molecules)

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Stage 1  Formation of conditioning layer

Stage 2  Planktonic bacterial cell attachment

Stage 3  Bacterial growth and biofilm expansion

Fig. 6.15  Stages of biofilm formation

ii. Coaggregation in which genetically distinct cells in suspension recognize each other and clump together (Fig. 6.16A). The detachment of microcolonies to detach from biofilm community can be in two forms: i. Erosion: Continual detachment of single cells and small portions of biofilm. ii. Sloughing: Rapid, massive loss of biofilm. Detachment shapes morphological characteristics of biofilm and serves as active dispersive mechanism (Seeding dispersal). Detached cells that have acquired resistance traits from parent biofilm community, can be a source for persistent infection. Biofilm in Endodontics: When there is infection in the root canal, its nutritional and environmental status is altered. It becomes more anaerobic. Nutritional level is depleted making it a tough ecological niche for surviving microorganisms. This favors biofilm formation both

in primary and post-treatment Endodontic infections. Microbes persist in anatomical complexities such as isthmus, deltas and in apical portion of root canal system and may also invade beyond the apical foramen.

Types of Biofilm 1. Intracanal Microbial Biofilms: – Formed on root canal dentine of Endodontically infected tooth – Intracanal bacterial biofilm was documented in detail by Nair in 1987 – Composed of loose collection and biofilm structure of cocci, rods and filamentous bacteria – Monolayer and/or multilayered bacterial biofilms adhere to the dentinal wall of root canal – Intracanal biofilm has extracellular matrix material of bacterial origin interspersed with cell aggregates

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2. Extraradicular Microbial Biofilms: – Also called root surface biofilms – Formed on root (cementum) surface adjacent to root apex of Endodontically infected teeth – Composed of cocci, short rods and filaments, with cocci attached to tooth substrate – Smooth structureless biofilm containing extracellular matrix and embedded bacterial cells found to coat the root tip adjacent to the apical foramen – Calcified extraradicular biofilms were found in cases of periapical inflammation and delayed periapical healing in spite of adequate orthograde nonsurgical Endodontic treatment.

A

B Figs 6.16A and B  Schematic representation of coaggregation and co-adhesion between different bacterial cells forming biofilm

– E. faecalis can develop biofilms according to prevailing environmental and nutrient conditions: i. In nutrient-rich environment (aerobic and anaerobic): E. faecalis is found to produce typical biofilm structures with characteristic surface aggregates of bacterial cells and water channels. Viable bacterial cells present on biofilm surface. ii. In nutrient-deprived environment (aerobic and anaerobic): Irregular growth of adherent cell clumps. Dead bacterial cells and pockets of viable bacterial cells found.

Formation Stage 1: E. faecalis adhere and form microcolonies on the root canal dentine surface. Stage 2: Bacterial-mediated dissolution of the mineral fraction from dentin substrate was induced. Stage 3: Mineralization or calcification of E. faecalis biofilm due to localised increase in calcium and phosphate ions. Coaggregation interactions between E. faecalis and F. nucleatum occur and contribute to Endodontic infections.

3. Periapical Bofilms: – Isolated biofilms found in periapical area of Endodontically infected teeth – Actinomyces and P. propionicum have been found in asymptomatic periapical lesions refractory to Endodontic treatment. – Actinomyces has yellow granular appearance (called sulfur granules). Periapical biofilm structure is granular containing central mass of intertwined branching bacterial filaments held together by extracellular matrix with peripheral radiating clubs. – Phagocytes cannot engulf bacteria in matrix enclosed biofilm structure. 4. Biomaterial Centered Infection (BCI): – Bacteria adheres to an artificial biomaterial surface to form biofilm. – When biomaterials are present in close proximity to the host immune system, it increases susceptibility for BCI. – It is a major complication associated with prosthesis and implant-related infections. In Endodontics, it can form on root canal obturating materials and can be intraradicular or extraradicular depending on whether the obturation material is within the canal or extruded beyond apex. – Microbes associated with BCI: Coagulase negative Staphylococcus, S. aureus, enterococci, streptococci, P. aeruginosa and fungi found from infected biomaterial surfaces. E. faecalis, S. sanguinis, S. intermedius, etc. have been isolated from biofilms related to obturation material. Gram-positive facultative anaerobes can colonize and form extracellular matrix on GP points. Serum plays a role in biofilm formation. – Bacterial adherence to biomaterial surface is described in following phases:

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Fig. 6.17  Mind-map to remember all points of Biofilm

- Phase 1: Transport of bacteria to biomaterial surface - Phase 2: Initial, nonspecific adhesion phase - Phase 3: Specific, adhesion phase. – Clinical Significance: Apical periodontitis is essentially a biofilm-induced disese. The structure of Biofilm and the resident microorganisms is such that it is resistant to antimicrobial agents such as antibiotics, disinfectants or germicides. Endodontic treatment should focus on elimination of microbes that colonize infected root canal system (by means of Antisepsis) and prevent introduction of new microorganisms in the canal

(by means of Asepsis). For the disruption of biofilm and reduction of microbial load, combination of mechanical instrumentation and various root canal irrigants and disinfectants such as Sodium hypochlorite, Chlorhexidine digluconate, MTAD, calcium hydroxide, etc. are being used. Also other methods such as use of Endoactivator, Ultrasonics, Lasers, Ozone therapy, etc. are being employed to eradicate biofilms and achieve complete root canal disinfection. These have been discussed in detail in Chapter 15: Disinfection of the Root Canal System. Mind-maps to remember all points of biofilm are given in Figures 6.17 and 6.18.

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Fig. 6.18  Mind-map to remember types of Endodontic biofilm

BIBLIOGRAPHY 1. Cohen S, Hargreaves KM. Pathways of Pulp, 9th edn. St. Louis: Mosby; 2006.pp.541-79, 580-607.

2. Grossman L, Oliet S, Del Rio C. Endodontic Practice, 11th edn. Varghese Publication; 1991.pp.234-41. 3. Ingle J, Bakland L, Baumgartner J. Ingle’s Endodontics 6, 6th edn. BC Decker Inc, Hamilton; 2008.pp.268-308.

CHAPTER

7

Diagnosis and Diagnostic Aids in Endodontics

This chapter describes a systematic and methodical approach towards making an accurate diagnosis. It includes the various odontogenic and nonodontogenic causes of orofacial pain, which sometimes presents a true diagnostic and therapeutic challenge to the clinician. The chapter also explains in detail the various diagnostic aids in Endodontics.   You must know •  What is Diagnosis and how to be a Successful Diagnostician? • What are the Steps to be followed to Arrive at an Accurate Diagnosis?

WHAT IS DIAGNOSIS AND HOW TO BE A SUCCESSFUL DIAGNOSTICIAN? Diagnosis is the process of evaluating the patient’s health and the resulting opinion formulated by the clinician. “Oral diagnosis is a systematic method of identifying an oral disease process on the basis of facts obtained from history, clinical examination and various diagnostic tests”. Making an accurate diagnosis is an Art and Science. Figure 7.1 shows the requirements for making correct diagnosis.

Prerequisites of proper diagnosis: To be successful in diagnosis, the diagnostician should have: PATIENCE, INTEREST, CURIOSITY, KNOWLEDGE, SENSES to be alert, INTUITION EQUIPMENT (Instruments and devices) for examination and diagnostic tests. (Remember the above prerequisites of the diagnostician as: An excellent diagnostician P I C K S It Early). “Symptoms are defined as phenomena or signs of a departure from the normal and indicative of illness.” (Grossman’s Endodontic Practice, p.1).

WHAT ARE THE STEPS TO BE FOLLOWED TO ARRIVE AT A CORRECT DIAGNOSIS?

Fig. 7.1  Requirements for making correct diagnosis

Flow chart 7.1 shows a simplified chart showing steps in diagnostic process. Diagnostic process should be methodical and systematic.

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Flow chart 7.1  Simplified chart showing steps to make an accurate diagnosis

Differential diagnosis: It is the technique of distinguishing one disease from several other similar disorders by identifying their differences. Diagnosis by exclusion: It is the technique in which all possible diseases under consideration are eliminated until one remaining disease correctly explains the patient’s symptoms.

STEP 1: CASE HISTORY TAKING Case history taking is an active dialogue between the clinician and the patient. The clinician asks a set of leading questions and carefully interprets the answers. A written case history form can be filled in by the patient and then verified and reviewed by the clinician.

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Chief Complaint The reason for the patient seeking dental care/treatment should be documented in patient’s own words. With this expressed chief complaint, the clinician can determine the nature and order of events that lead to the patient’s complaint.

Medical History • Enquire about the general health of the patient and about the presence of any medical problems. Completion of a preprinted comprehensive medical history form is mandatory. It gives clinician information about presence of any medical problems and serves as baseline record. It needs to be updated, especially if the patient comes for a recall check-up or other dental problems after a long time. • Need: Information about the medical problems is necessary as: – Some medical conditions may require modification in providing dental care. For example, in case of hypertension, Local anesthesia without adrenaline may have to be used. In patients taking drugs such as Ecosprin, it needs to be discontinued with the consent of patient’s physician before performing any surgical procedure. Antibiotic prophylaxis is indicated for patients with congenital or rheumatic heart disease. – Some medical conditions may have oral manifes­ tations. For example, AIDS, diabetes mellitus. – Some oral soft tissue changes are related to medications used to treat the medical condition. For example, nifedipine, an antihypertensive drug induces gingival hyperplasia. – It helps to determine the risks to the clinician and staff and risk to the patient due to presence of particular medical condition. – In medically compromised patients, it helps to determine the risk of treatment against the risk of nontreatment. Thus, the medical history will enable the clinician to determine the need for: - Medical consultation, - Any modification of therapy, - Any premedication • The American Society of Anesthesiologists has developed a system to determine the extent of risk in medically complex patients. These guidelines can be followed.

• History of illness requiring hospitalization in the past should be enquired for. • Any known drug allergy. • Whether the patient is taking any Medications (prescription medications as well as over the counter medications). The clinician may have to consult with the patient’s physician and decide about the dental treatment modifications that will have to be made in order to provide the appropriate care.

Dental History Present Dental Illness Questions

Open ended: Leaves patient open for discussion Closed: Response is Yes or No

Open-ended questions are encouraged to obtain specific information regarding the present illness from the patient such as: • Onset of symptoms and its intensity: When did the symptoms first started and what is the intensity of symptoms. Spontaneous – Onset Initiating event Trauma Biting on hard object After dental visit for a restoration – Intensity of symptoms: Whether the Mild symptoms are Moderate Severe • Duration of symptoms: Whether the symptoms are: – Momentary – Lingering • Progress: Whether intensity of symptoms is increasing or decreasing. • Aggravating factors may be: Biting, temperature changes, etc. • Relieving factors may be: Medications, holding cold water in mouth, etc. Provocation and relief factors may help to determine which diagnostic tests should be performed to establish a more objective diagnosis. • Localization of area or tooth: Whether the patient can point the offending tooth or the symptoms are not welllocalized and radiating to which all areas.

Diagnosis and Diagnostic Aids in Endodontics

Past Dental History • Information regarding the last dental visit. • Whether there has been any recent dental treatment. This may help to localize a particular problem.

Pain History This involves both careful listening and astute questioning. The clinician has to determine the source of pain. Odontogenic Source of pain Nonodontogenic Well-localized •  Location Diffuse Superficial Location Deep – Easily localized superficial pain: May be Cutaneous or Neurogenic origin. – Deep pain, that may be localized when provoked: May be Musculoskeletal in origin – Deep diffuse pain: May be Somatic, Visceral or Musculoskeletal. – Superficial and spreading pain: May be Neurogenic rather than a Cutaneous source. • Intensity: Can be determined using Verbal Analog Scale which means on a scale of 0–10, with 0 being no pain and 10 being the worst pain, how does the patient rate the pain. Sudden • Onset of pain Gradual This helps to determine the etiology. Unchanging pain that has been present over a protracted period is highly suggestive of a nonodontogenic source. Whether the pain is – Spontaneous – Elicited with hot/cold/chewing • Duration of pain – Momentary – Lingering • Whether the pain is Continuous or Intermittent • Nature of pain – Dull ache (May be muscular) – Sharp shooting – Shock like, Burning (May be neurogenic) – Throbbing, pulsatile (May be vascular)

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• Progression of pain: Whether the pain has reduced, become worse or same (unchanged). • Aggravating factors: Factors that precipitate or aggravate pain help in directing objective tests. The lack of aggravating factors indicates that the pain is nonodontogenic. • Relieving factors: Factors that alleviate pain. – Whether the pain is responsive to specific medication – Moderate intensity pain but unresponsive to antiinflammatory drugs suggests a noninflammatory origin. • Associated factors: Such as swelling, discoloration and numbness.

Orofacial Pain/Dental Pain Definition of Pain “Pain is defined as an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage.” (International Association of Study of Pain (IASP). By far ‘pain’ is the most important/only factor that provokes the individuals to seek dental care.

Classification • Classification of dental pain:

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Referred Pain “The perception of pain in one part of the body that is distant from the actual source of pain is known as Referred pain”. • Pain of nonodontogenic origin can refer pain to teeth. Also teeth may refer pain to other teeth as well as to other anatomic areas of the head and neck. • It is provoked by intense stimulation of pulpal C-fibers that cause intense, slow, dull pain. • Referred pain always radiates to Ipsilateral side of the tooth involved. • Rarely, anterior teeth refer pain; Posterior teeth may refer pain to Opposite arch, to Periauricular area, or rarely to anterior teeth.

Orofacial Pain of Nonodontogenic Origin Rhinosinusitis and Endodontic Disease

• Classification of pulpal pain:

Maxillary rhinosinusitis is the most common nonodonto­ genic cause of dental pain. Pain may get referred from the maxillary sinus to the maxillary dentition primarily due to the close anatomic relationship between the floor of the maxillary sinus and the roots of the posterior maxillary teeth. Thus, two important conditions to be considered during diagnosis include: 1. Referred dental pain from maxillary sinus (Figure 7.2 shows points explaining the mechanism how pain gets referred to teeth from inflammed maxillary sinus). 2. Maxillary sinusitis of dental origin (MSDO) (Figure 7.3 shows points explaining the mechanism how dental infection can spread to the maxillary sinus). The distinguishing points of Rhinosinusitis and Odontalgia due to Endodontic disease are listed in Table 7.1. Figure 7.4 shows schematic representation of spread of periapical infection from maxillary second premolar into the maxillary sinus.

Fig. 7.2  Mechanism of referred dental pain from maxillary sinus

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TABLE 7.1  Distinguishing points of rhinosinusitis and odontalgia due to Endodontic disease Symptoms of rhinosinusitis

Symptoms of odontalgia

• Dull aching dental pain that is difficult to pinpoint or localize to a single tooth

• Pain of pulpal origin is more easily localized

• Positional changes can cause increased pain due to movement of mucosal fluid over sensitive sinus ostium or it can be due to raised intracranial pressure from blood flow. Throbbing or increased pain sensation is felt on lying down or when the head is placed lower than the level of heart

• Positional changes generally do not affect pain of pulpal origin except in some cases of irreversible pulpitis

• Fullness or pressure below eyes and on external palpation of cheeks

• No such fullness or pressure

• Often all the teeth that are proximate to the sinus floor are tender to percussion

• Usually only the offending tooth is tender to percussion

• Symptoms may be severe, but there is sudden and total relief if drainage is established and sinus pressure is alleviated

• Symptoms may vary from mild to moderate to severe depending on the cause. Endodontic treatment provides total relief from severe pain due to irreversible pulpitis

• Application of local topical anesthetic to maxillary sinus ostium can relieve perceived dental pain in case of referred sinus pain. Anesthetic nerve blocks will not abate pain of rhinosinusitis

• Sometimes, administration of local anesthetic nerve block causes relief of dental pain

• Generally the tooth in question responds within normal limits to a pulpal stimulus such as electric pulp test or thermal test such as ice, when compared with other healthy teeth

• To detect the offending tooth and the etiology of dental pain, the pulp vitality test is the key diagnostic test. It helps to effectively differentiate maxillary sinus etiology from pain of pulpal origin

Periapical infection from maxillary second premolar has spread into the maxillary sinus shown by big arrow. Small arrow-heads indicate the floor/lining of maxillary sinus. Localized mucosal thickening in the adjacent sinus mucosa in response to apical periodontitis in a maxillary posterior tooth is referred to as periapical mucositis. It is asymptomatic and resolves following Endodontic treatment.

Dental Pain of Myofascial Origin: Myofascial Pain vs Pulpal Pain • Myofascial pain originate from small foci of muscle tissue termed as TRIGGER POINTS.

Fig. 7.3  Mechanism of spread of dental infection to maxillary sinus

Fig. 7.4  Schematic representation of spread of dental infection in maxillary sinus from infected maxillary second premolar. Big arrow indicates how periapical infection from maxillary second premolar has spread into maxillary sinus and small arrow heads indicate floor/ lining of maxillary sinus

• Myofascial pain is described as diffuse, constant, dull, aching sensation, which may be misdiagnosed as pulpal pain. • Masticatory muscle pain is felt when chewing. This pain is triggered by contraction of masticatory muscles rather than loading of PDL. Palpation of masticatory muscles will reproduce pain whereas percussion of teeth will not. • Etiology of myofascial pain: Injury or sustained contraction such as clenching/parafunctional habit.

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• Dental pain of myofascial origin may or may not be associated with pulpal or periapical pathosis. • Dental pain of myofascial origin can be diagnosed based on following: – Local anesthetic block will not resolve symptoms but if local anesthetic is administered into trigger point, it will resolve symptoms – Lack of symptoms after pulp testing – Palpation of masticatory muscles will elicit pain – Percussion of teeth will not elicit pain.

Neurovascular Pain vs Pulpal Pain Neurovascular pain presents mainly as headache with accompanying toothache perceived secondary to headache. Primary headache is of three types: 1. Migraine 2. Tension-type headache 3. Cluster headache • Migraine presents as unilateral, pulsatile, moderate to severely intense headache which is likely to be aggravated with routine physical activity. Patients may experience nausea or vomiting or photophobia. • Tension-type headache does not mimic toothache. • Pain of neurovascular origin presenting primarily as toothache is more likely to be cluster headache. Cluster headaches occur in episodes lasting for 15 minutes to 2 hours. There may be 1–8 such episodes in a day. Presents as unilateral, excruciating orbital, supra-orbital or temporal pain. Other symptoms may be ipsilateral nasal congestion, rhinorrhea, lacrimation. Elimination of pain following 10-minute inhalation of 100% oxygen is diagnostic for cluster headache. Referred pain is felt in maxillary anterior or premolar teeth.

Important Diagnostic Features

Trigeminal neuralgia: It can be diagnosed based on: • There is intense, sharp, shooting pain on stimulation of trigger zones and is unilateral. • Slight pressure on trigger zones results in severe pain. This pain usually subsides within few minutes until triggered again. • Trigger zones for trigeminal neuralgia may be intraoral and may be triggered by chewing. • Administration of local anesthetic in the area of trigger zones may resolve the symptoms and can be misleading. • Sharp, shooting pain in the absence of dental etiology should alert the clinician to include trigeminal neuralgia in differential diagnosis.

Cardiac Pain • Cardiac pain may be referred to left side of mandible. • Cardiac pain can be spontaneous and diffuse similar to pulpal pain. • Diagnostic features: – Associated medical history pointing to cardiac problem – Cardiac pain will not get aggravated by local provocation of teeth – Administration of local anesthetic will not reduce the pain.

Psychogenic Pain • Patient will have complaint of toothache, yet lacks a physical cause. • Psychogenic toothache is very rare. • Diagnosis of psychogenic toothache only by ruling out all other potential diagnoses. • Psychogenic pain may be precipitated by severe psychologic stress. It may not follow any anatomic distribution. Pain may be felt in multiple teeth. A Mind-map to remember all points of case history taking (Fig. 7.5).

• Neurovascular pain occurs in episodes with complete remission between episodes whereas pulpal pain will be continuous or may present as discomfort between any aggravating episodes. • Local anesthetic administration is unpredictable. • Administration of oxygen to rule out cluster headache can make definitive diagnosis.

General

Neuropathic Pain vs Pulpal Pain

Temperature

Neuropathic pain arises from abnormalities in neural structures.

• An elevated body temperature (fever) indicates total body reaction to inflammatory disease.

STEP 2: CLINICAL EXAMINATION • The clinician must observe the patient as he/she walks into the operatory by his/her gesture and body language. • Obtain and record the patient’s vital signs: (TPR BP) Temperature, pulse rate, respiratory rate, blood pressure.

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Fig. 7.5  Mind-map to remember all points of case history taking

• Normal body temperature is 98.6oF. A temperature above this but below 100oF indicates localized disease. Localized disease can be treated: • By removing the cause (Root canal opening and cleaning and disinfection) and/or • Incision and drainage (I and D). Pulse rate: Normal pulse rate is 60–100 beats per minute. Stress and anxiety can cause elevated pulse rate. Respiratory rate: Normal respiratory rate is 16–18 breaths per  minute. This rate also gets elevated due to stress and anxiety. Blood pressure: Normal BP is 120/80 mm Hg for persons under 60 years of age and 130/90 mm Hg for persons over age of 60 years.

No dental treatment should be done if blood pressure readings of diastolic pressure is over 100 mm Hg on that day. Consent and consultation with the patient’s physician needs to be done. Sometimes, elevated blood pressure is caused only by stress and anxiety of the moment and must be dealt with reassurance or pretreatment sedation if required. • Other abnormalities such as breathlessness, altered gait, unusual body movements must be recorded. • Cancer screening of soft tissues: Extraoral and intraoral soft tissues must be evaluated for any kind of lump, swelling, white spots or scaly patches or sore spots for early detection of any precancerous or cancerous lesion.

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Extraoral Examination • Patient is examined for any signs of facial asymmetry. Figure 7.6 shows photograph of a patient having facial asymmetry due to extraoral swelling on left side. • Any localized swelling, change in color, bruises, or similar signs of disease, trauma or previous treatment should be looked for. • Inspection and palpation of painful and/or enlarged lymph nodes. • Any opening of sinus tracts through skin of face. • Extent and manner of jaw opening. • Temporomandibular joint examination—any tender­ ness, clicking, irregular movement, etc.

Intraoral Examination

Fig. 7.6  Facial asymmetry due to extraoral swelling on left side (Courtesy of Dr Manoj Ramugade)

Visual and Tactile Inspection • For careful inspection, there should be good light and dry conditions and good mouth mirror and probe/ explorer. • Magnification in the form of Loupes and dental operating microscope allow the clinician to visualize what cannot be observed with naked eye. • Inspection of:

Fig. 7.7  Photograph showing generalized hypoplastic maxillary teeth (Courtesy of Dr Samir Khaire)

Figure 7.7 shows photograph of a patient with changes in color, contour and consistency of all maxillary teeth due to hypoplasia. The clinician should avoid “tunnel vision”–that is examining only the area of chief complaint of the patient.

Palpation • Manual digital palpation, i.e. palpation with fingers of soft and hard tissues around the tooth in question should be done. Figure 7.8 shows photograph demonstrating manual digital palpation in the mucobuccal fold of maxillary left canine.

Fig. 7.8  Photograph showing manual digital palpation in the mucobuccal fold of maxillary left canine (Courtesy of Mr Amar, Dr Dabholkar’s clinic)

Diagnosis and Diagnostic Aids in Endodontics

Location of swelling • Anterior part of palate (Figure 7.9 shows photograph of swelling in anterior part of palate due to spread of infection from maxillary right lateral incisor) • Posterior palate • Mucobuccal fold of maxilla fold

Fig. 7.9  Swelling in anterior part of palate due to spread of infection from maxillary right lateral incisor shown by arrow

Presence of tenderness on palpation should be noted. • It is recommended that the clinician should Always bilaterally palpate both the area in question and the contralateral side. • Palpation of lymph nodes to note any lymph node enlargement, tenderness, mobility and consistency. Infection from anterior teeth may cause enlarge­ ment of submental lymph nodes. Infection from mandibular molar teeth involve submandibular lymph nodes. In acute infection, involved lymph nodes are usually firm, tender and palpable. In chronic infection, lymph nodes may be palpable but no pain. Hard and fixed lymph node with stone-like consistency indicates malignancy. • Palpation of temporomandibular joint (TMJ) may be done in cases of TMJ-related problems such as clicking, restricted movement, deviation in movement. • Intraoral swelling should be palpated to determine if the swelling is: Diffuse Swelling Localized Firm Swelling Fluctuant • Location of swelling can determine the offending tooth from which it has originated.

• Mandibular mucobuccal fold

• Tonsillar and pharyngeal areas

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Offending tooth Apex of maxillary lateral incisor or Palatal root of maxillary first premolar

Palatal root of one of the maxillary molars Apex of root of any maxillary tooth that exits the alveolar bone on the facial and inferior to muscle attachment Apex of root of any mandibular tooth that exits the alveolar bone on the facial and superior to the level of muscle attachment Severe infection involving maxillary or mandibular molar

Percussion • Pain to percussion indicates inflammation of the periodontal ligament (PDL) • First gently percuss digitally with gloved finger • Then percuss with the butt end of the mirror handle (Figure 7.10 demonstrates the percussion of upper right canine with butt end of mirror handle). • Always the contralateral tooth should be first tested as control and also other adjacent teeth that are certain to respond normally • First vertical percussion is done—that is percussing occlusally Then lateral percussion is done—that is buccal and lingual aspects of teeth. Sometimes the patient is not able to locate the tooth with pain. On percussion of the involved tooth and other adjacent teeth, patient may be able to localize painful tooth. Inflammation of PDL causing tenderness on percussion may be due to physical trauma, occlusal prematurities, periodontal disease or due to extension of pulpal disease into the PDL space.

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Fig. 7.10  Percussion of upper right canine with butt end of mirror handle (Courtesy of Mr Amar, Dr Dabholkar’s clinic)

Mobility and Depressibility Mobility of teeth indicates either loss of periodontal attachment due to trauma, parafunctional habits, periodontal disease, root fracture or it could be extension of infection from pulp to PDL space. Once the initiating factors are eliminated or treated, the mobility reverses to normal. Lateral movement of tooth in socket is called mobility. Vertical movement of tooth in socket is called depressibility. This test is performed using back ends of two mirror handles—one on buccal aspect of tooth and one on lingual aspect of tooth as shown in Figure 7.11.

Fig. 7.11  Back ends of mirror handles to check mobility of tooth (Courtesy of Mr Amar, Dr Dabholkar’s clinic)

• The periodontal probe is “stepped” around the long-axis of the tooth, progressing in 1 mm increments. Diagnostic criteria given by Harrington to determine whether the periodontal defect is of Endodontic or periodontal origin: – If periodontal probe Sinks abruptly into an isolated periodontal defect, it could be due to Vertical root fracture. – If periodontal probe Steps down into a periodontal defect and a similar finding occurs on the contralateral side of the arch, it could be due to a generalized periodontal disease. • Furcation defect or bone loss can occur secondary to periodontal or pulpal disease. Furcation canals can be a portal of exit for necrotic pulp tissue byproducts. Clinical furcation probing and radiographic assessment of the furcation defect is done. Grades of furcation involvement:

Periodontal Examination • Periodontal probing is an essential part of the diagnostic process. • Each tooth is evaluated in atleast three locations— mesial, middle and distal aspect, on both buccal and the lingual surfaces. • Periodontal defects could be a sign of either an Endodontic or a periodontal problem.



Figure 7.12 shows mind-map to remember all points of clinical examination.

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Fig. 7.12  A mind-map to remember all points of clinical examination

RADIOGRAPHS The radiograph is one of the most important diagnostic aid in Endodontics. It is an indispensable tool of Endodontic practice. Radiograph is referred to as the ‘Third Eye’ of the Dentist as it permits visual examination of oral structures that would otherwise be unseen by naked eye. Radiographs are essential to all phases of Endodontic therapy. There uses can be categorized as:

Diagnostic Uses • In Endodontics, primary radiograph is IOPA view to determine:

– Involvement of pulp/presence of pulpal disease: (Crown of tooth).   Detection of CARIES and its extent in relation to the pulp chamber. Figure 7.13 shows a radiograph showing deep occlusal caries in maxillary first molar approaching the pulp.   Remaining dentinal thickness (RDT) can be estimated through the preoperative radiograph suggesting whether caries is approaching the pulp or away. – Anatomy of pulp and root and variations (Root of tooth): - Number of roots and root canals - Width of canals - Complete or incomplete root formation - Curvatures - Presence of pulp stones, calcification - Presence of fused or extra roots and canals, accessory canals, any bifurcation or trifurcation in root canal system - Additional root Radix Ento/Paramolaris

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– To view the periradicular area: - Integrity of lamina dura and PDL space - Bone loss in the area of periapex - Radiolucency in the periapical area   Figure 7.14 shows a radiograph showing deep caries lesion in the crown and periapical radiolucency in relation to the mesial root of mandibular first molar – To view pathological conditions like: - Fracture of roots - Resorption -  Internal -  External

– Normal radiolucent and radiopaque anatomic landmarks: that lie in close proximity, which should be distinguished from pathological lesions. – Periodontal considerations – A good preoperative IOPA gives an idea about the orientation and depth of angulation of handpiece for access opening. A grid can be used to obtain near about exact measurements. • Bitewing radiographs can be used as a supplemental film to determine: – Anatomic extent of pulp chamber – Interproximal caries – Recurrent caries – Pulp stones – Calcifications – Depth of existing restoration – Crestal height of bone   It is useful when very young children are being examined.   Bitewing view shows the involvement of nasal cavity, maxillary sinus, floor of mouth, etc.   Diagnostic radiographs must be best radiographs as possible. Two to three radiographs with 10–20° change in horizontal angulation change can provide lots of information which can be missed otherwise.

Therapeutic Uses

Fig. 7.13  Radiograph showing deep occlusal caries in mandibular first molar approaching the pulp

For treatment radiographs, technique is even more critical. With rubber dam in place, visibility is reduced, sometimes it may be difficult to expose working radiographs. During Endodontic treatment, radiographs are useful for: • For determination of working length (Fig. 7.15) • Examining the position of an instrument within the root to localize hard-to-find and negotiate root canals • To determine position and adaptation of master cone • To evaluate obturation • During root end surgery, to localize the apex and following root end surgery, to confirm before suturing that all tooth fragments and excess filling material have been removed.

Prognostic Uses

Fig. 7.14  Radiograph showing deep carious lesion in the crown and periapical radiolucency in relation to mesial root of mandibular first molar

• To evaluate the outcome of treatment: – Success: Radiographic evidence of resolution of lesion and re-establishment of normal periapical structures. – Failure: Persistence or emergence of radiographic signs of disease.

Diagnosis and Diagnostic Aids in Endodontics

• • • • • • Fig. 7.15  Radiograph taken with no. 15 k-files in the four root canals of maxillary first molar tooth for estimation of working length (Courtesy of Dr Shivani Bhatt)

• Resolution and healing of pretreatment periapical lesion is determined. (Refer figures 8.2 A to D, that shows portion of panoramic image in which periapical lesion/ radiolucency has resolved after Endodontic treatment) • Any new lesion developed in the periapical area, after the treatment can be detected (Recurrent or de novo infection).

• •

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of normality and pathosis if not coupled with proper history and clinical examination and testing. Radiographic appearance of Endodontic pathosis can sometimes be subjective. Lesions of medullary bone often go undetected unless there is marked resorption or until the resorption has eroded a portion of the cortical plate. There is risk of receiving small doses of ionizing radiation if techniques and necessary precautions are not properly executed. Improper technique resulting in errors, having to retake or repeat the radiographs increasing further exposure. Superimposition of anatomic structures. Distortion due to improper chemical processing with conventional radiography procedures. Various pulpal pathologies may be indistinguishable on radiographs. Periradicular soft tissue lesions cannot be accurately diagnosed by radiographs, they require histologic verification. For example, chronic inflammatory tissue cannot be differentiated from healed, fibrous, scar tissue.

REQUIREMENTS OF A GOOD RADIOGRAPH • For Endodontic purposes, radiograph should depict the tooth in the center of the film. Center of the film contains least amount of distortion. • At least 3 mm of bone must be visible beyond the apex of tooth. • Image on film must be as anatomically correct as possible. • Radiograph should be accurate with no elongation or foreshortening.

LIMITATIONS OR DRAWBACKS OF RADIOGRAPHS • Radiographs provide two-dimensional image of threedimensional object. Additional radiographs at different angulations have to be taken to obtain the desired information. • Radiograph is only an adjunctive tool and can be misleading. Radiographs alone cannot be used for diagnosis. Radiograph alone can lead to misinterpretation

RADIATION SAFETY ALARA principle: As Low As Reasonably Achievable. As per this principle, ‘No matter how small the radiation dose, there still may be some deleterious effects’. It is best to keep the ionizing radiation to a minimum for protection of both the patient and the dental staff.

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Principles of ALARA Clinical Aspect • Use of protective lead aprons and thyroid collars. • When exposing films, clinician should stand behind a barrier or atleast 6 feet away from the patient and in an area that lies between 90o and 135o to the beam. • Film badges for recording exposure can be worn by all dental personnel who might be exposed to occupational X-radiation. • Use of meticulous radiographic technique to reduce the number of retakes and exposures.

Technical Aspect • Select fast (i.e. sensitive) speed film, either Ultraspeed (U) or E. • Use dental units with 70 kvp or higher kilovoltage since lower kvp causes increased patient’s skin dose. Optimally 90 kvp should be used. • Units operating at 70 kvp must have filtration equivalent of 2.5 mm of aluminum to eliminate the low-energy X-rays before patient absorbs them. • Collimation with lead diaphragm restricts the X-ray beam size so that it does not exceed 2.75 inches (7 cm) at the patient’s skin surface. • Open-ended, circular, or rectangular lead-lined cylinders are called position-indicating devices (PIDs) are recommended as they direct the beam to target and collimate the X-ray beam reducing patient exposure. PIDs should be at least 12–16 inches long. Pointed cones should not be used as they produce increased amount of scatter radiation. It should be understood that digital detectors are much more sensitive to radiation as compared to conventional direct exposure emulsion X-ray films. So, digital detectors require lower radiation exposure. With digital radiography there is 50–90% reduction in exposure as compared to conventional film-based radiography. Thus, digital radiography plays an important role in radiation safety.

Conventional Radiography • Requires use of conventional standard films and processing chemicals. • Requires dark room procedures for processing of radiographs. • Increased radiation exposure. • Perfectly exposed and perfectly processed radiograph is required for it to have good diagnostic quality. Proper dark room organization, film handling and adherence to time and temperature method of film processing play an important role in producing good images.

Xeroradiography • Xeroradiograph can be exposed by conventional X-ray machine using less than usual radiation. It is automatically processed and delivered as a dry, laminated permanent film in 25 seconds. • Xeroradiography produces images of sharper clarity and finer detail.

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Digital Radiography

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Radiography (RVG)

Dr Francis Mouyen, a French Dentist, developed a prototype digital radiographic system that he named Radiovisiography (RVG). Since 1989, there have been seven newer generations of RVG. • Digital radiography uses no X-ray film and requires no chemical processing. It uses a sensor to capture the image created by the radiation source. • The sensor is either directly or remotely attached to a local computer. • The computer interprets the signal and using a specialized software translates the signal into a digital image that is displayed on the monitor almost instantly. • The image can be enhanced, magnified/zoomed, colored, contrast adjusted, etc. in order to visualize it better or as a tool for patient education. • The image is stored in the patient’s file, in a dedicated network server and can be recalled whenever needed. Digital imaging systems require: • An electronic sensor or detector • An analog-to-digital converter • A computer • Monitor • Printer Figure 7.16 shows the photograph of the monitor and the electronic sensor for digital radiography. Figure 7.17 shows the mandibular posterior region radiograph taken using digital radiography.

Digital Subtraction Radiography • This technique is based on the fact that: ‘Given radiographs taken in precisely the same position and with the same beam geometry and exposure parameters, images can be subtracted to show changes over time’.

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Fig. 7.16  Photograph showing the monitor and the electronic sensor for digital radiography

• Images can be manipulated for the purpose of enhancement, contrast, etc. for viewing it better. They can also be colorized for patient education. • Images can be duplicated any number of time without any loss of image quality. • Digital systems provide certain measurement tools that can accurately measure, for example, root canal working length. • Multiple exposures, from various angles, both horizontal and vertical, may be made without moving the sensor once positioned.

Disadvantages of Digital Imaging System

Fig. 7.17  Radiograph of mandibular posterior region taken using digital radiography (RVG)

• It detects changes in radiographic density over time. • It can evaluate osseous healing after treatment. • All anatomic structures that have not changed between radiographic examinations are subtracted. So, the changes in diagnostic information become easier to interpret.

Advantages of Digital Radiography Over Conventional Radiography • Radiographic images are obtained instantly. • Radiation exposure is reduced from 50% to 90% compared with conventional film-based radiography. • Elimination of radiographic film and processing chemicals and hence elimination of errors associated with them. • Image enhancement, storage, retrieval and even transmission of images to remote sites in digital format.

• High initial cost • Difficulty in placing the sensor as most of the solid state detectors are somewhat thicker and more rigid • Potential for reduction in image quality when compared with conventional radiography • Mishandling can cause mechanical damage with high replacement costs for CCD and CMOS detectors.

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Paralleling Technique • Also called long cone or right angle technique. • Film is placed parallel to long-axis of teeth and the central beam is directed at right angles to the film and aligned through root apex. • Parallel placement of film is difficult due to variations in size and shape of oral structures (shallow palatal vault, tori, long roots, shallow floor of mouth, etc.). To compensate for difficult placement, film can be positioned so that it diverges as much as 20˚ from longaxis of tooth.

Modified Paralleling Technique • This technique increases vertical angulation by 10˚–20˚. • This orientation causes a small degree of foreshortening but clear periradicular radiograph of maxillary posterior region can be obtained. • Also, a distal angulated radiograph 10o–20o distal shift of cone from the distal with beam directed towards mesial, projects the buccal roots and the zygomatic process to the mesial, thus increasing clarity.

If the angle of the film in relation to long-axis of teeth is no greater than 20o and the beam is directed at right angle to the film, no distortion occurs, although reduced definition of few structures may occur. But the resulting radiograph is considered adequate.

Bisecting Angle Technique

Horizontal Angulation

• Film is placed directly against the teeth without deforming the film and the central beam is directed perpendicular to an imaginary line that bisects the angle between the tooth and the film. • Generally the projected length of the tooth is same as the actual length of the tooth in this technique but the resultant image has the potential for distortion, superimposition, etc. • It is used only when modified paralleling technique cannot be used.

In Endodontic therapy, a technique to vary the horizontal angulation of the central ray of X-ray beam can be used to visualize the ‘third’ dimension (i.e. ‘Spatial’ or buccolingual relation of an object). This technique has various names: Buccal Object Rule/Cone Shift Technique/Clark’s Rule/Slob Rule.

FILM HOLDERS To ensure film placement and parallelism, Film Holders can be used. Figure 7.18 shows photograph of film holder. Finger retention of the film is generally not recommen­ ded. A straight hemostat is a good film holder and additionally it aids in cone positioning as well.

Cone Angulation Vertical Angulation The cone is aligned so that the beam strikes the film at right angle.

Fig. 7.18  Photograph showing film holder (Courtesy of Dr Ritesh Mahashabde)

Application of Clark’s Rule helps: • To locate additional canals or roots • To distinguish between objects that have been superimposed • To locate foreign bodies • To determine buccolingual position of fractures • To locate anatomic landmarks in relation to root apex. Clark’s rule states that: “The most distant object from the cone (lingual) moves towards the direction of the cone”. It is called as SLOB rule (Fig. 7.19) Same Lingual Opposite Buccal (SLOB rule) The object that moves in the same direction as the cone is located toward the ‘Lingual’. The object that moves in the Opposite direction from the cone is located towards the ‘Buccal’.

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some time thoroughly reading the radiographic film and interpreting it. Film placement and cone angulation for individual teeth for Endodontic purposes Teeth 1. Maxillary anterior teeth 2. Maxillary premolars

3. Maxillary molars

4. Mandibular incisors 5. Mandibular canines 6. Mandibular premolars

Fig. 7.19  Schematic representation of the SLOB rule: Same Lingual Opposite Buccal (1) Mesial angulation (2) Perpendicular to tooth (3) Distal angulation (Courtesy of Dr Vishal Rathod)

Knowing the direction from which a radiograph was taken, mesial, straight on or distal, one can determine ‘Buccal’ and ‘Lingual’. Clark rule also applies to changes in vertical angulation. When the location of mandibular canal in relation to the root apices is to be determined, radiographs should be taken at different vertical angulations. If the canal moves with or in the same direction as the cone, the canal is Lingual to root apices. If the canal moves opposite the direction of cone head, the canal is Buccal to root apices. Ingle’s Rule is ‘MBD’, which states that ‘Always shoot from the Mesial and the Buccal root will be Distal.

RADIOGRAPHIC INTERPRETATION IN ENDODONTICS Radiograph should be carefully examined with an eye towards diagnosis and treatment. It is worth spending

7. Mandibular molars

Specific requirements Straight facial cone angle is preferred Mesial cone angulation is preferred. The right-angle horizontal projection produces single canal image in case of maxillary 1st premolar. By varying the angulation by 20o (Walton projection) the two canals are separated Mesial cone angulation is preferred. Standard right angle projection of maxillary 1st molar shows superimposition of roots with sinus floor, zygomatic process and overlap of roots. To view the roots clearly, horizontal angulation can be varied • With horizontal angulation 20o to the mesial, distobuccal root is cleared of the palatal root and the zygomatic process is ‘moved’ to distal of 1st molar • With horizontal angulation 20o to the distal, mesiobuccal root is isolated • Distal horizontal angulation is preferred • Separate canals in mandibular incisors can be viewed by varying the horizontal angulation • Mesial horizontal angulation is preferred • Mesial horizontal angulation is preferred • 20o mesial angulation will show separate canals if present or any bifurcation of canals • Distal horizontal angulation is preferred. • With standard perpendicular X-ray projection, the mesial or distal canals are superimposed appearing as single. • Walton projection causes roots to open up • 20o–30o mesial angulation separates the two canals in each root. Now that the four canals are seen on the radiograph, buccal canals can be distinguished from lingual canals by applying Ingle’s rule of ‘MBD’! Buccal canals are towards the distal and lingual canals are towards the mesial.

Systematic evaluation of each and every structure seen, should be done as follows:

Crown of Tooth Caries • Extent of caries in relation to pulp is determined. • Depth of proximal caries is more than what is seen on the radiograph. • Caries located on buccal or lingual aspect sometimes may give the false impression of pulpal involvement.

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Pulp Chamber

Periodontal Ligament Space

• Size of pulp chamber is observed. • Abnormal pulp calcification in response to caries or trauma may be seen. • Calcification may be diffuse or localized. • Sometimes, pulp chamber may appear to be obliterated. • Small areas of resorption, invaginated enamel, dens in dente, etc. these findings sometimes may be overlooked.

Resorption of apical lamina dura and widening of PDL space may occur as an early or limited response to infection in root canal system or may be due to increased tooth mobility occurring as a result of orthodontic movement, periodontal disease or parafunctional habits.

Root Pulp Canal/Root Canal • Number of canals, additional roots and canals, accessory, lateral canals should be looked for, while interpreting the radiograph for Endodontic diagnosis and treatment. Two or more radiographs at different angulations can be viewed and compared and then the findings can be interpreted. • Shape of the canals, curvatures should be noted. • Degenerative localized or diffuse calcifications in the radicular pulp. • Pulp obliteration.

Root Fracture Fracture of root may not be evident on radiograph but may result in reparative processes that become recognizable in later radiographs.

Root Resorption: External or Internal Internal resorption causes replacement of dentin by a soft tissue with resorbing cells. This may result in a balloonshaped lesion starting from the radicular pulp seen as round or ovoid radiolucent area observed on the radiograph. Internal pulp wall appears to be destroyed whereas cementum and periodontium seem to be unaffected in initial cases of internal resorption.

Periapical Area Integrity of Lamina Dura Determining the integrity of lamina dura has a diagnostic value when recent radiograph can be compared with previous one. Also, integrity or lack of integrity of lamina dura in relation to health of the pulp is to be determined.

Alveolar Bone • Density of bone in periapical area: Increased density of bone in response to infection may be seen in periapical area referred to as condensing osteitis. • Bone loss: Around the roots should be noted.

Periapical Pathology Periapical granuloma, cyst, abscess may be evident on the radiograph.

Anatomic Structures Sometimes normal anatomic structures may be misinter­ preted as pathoses. For example, mental foramen, incisive foramen will appear as radiolucencies in the periradicular area. They can be differentiated from pathologic conditions by exposures at different angulations and by pulp-testing procedures. Other anatomic radiolucencies include: Maxillary sinus, nutrient canals, nasal fossa, submandibular fossa, etc.

Differential Diagnosis Based on Radiographic Findings can be Interpreted Based on radiographic evaluation, following conditions may be suspected or diagnosed (As given in Ingle): • Hypercementosis: Cementum deposition around the roots clearly seen on radiographs. It may occur in response to pulpal inflammation without infection in apical part of canal. – Pulpitis would require Endodontic treatment. – Hypercementosis persists even after Endodontic treatment. • Condensing apical osteitis: It represents altered bone structure associated with chronic pulpitis and resolves following adequate therapy. • Idiopathic osteosclerosis: It may be closely located to apex of a vital tooth. – Does not require Endodontic treatment. • Marginal periodontitis: Its radiographic features are similar to apical periodontitis. If it is associated with

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necrotic and infected pulp, combined Endodonticperiodontal treatment is recommended. • Root fractures: It may be seen as a variant of apical periodontitis. When pulp canal space and the fracture slit are infected, it results in periodontitis, where the fracture communicates with periodontal space. In vertical root fracture (VRF), the whole length of root may be affected, producing a diffuse halo of radiolucent bone around the root. • Osteomyelitis: Sequestration of bone and apparently normal bone structures are seen between areas of bone destruction. • Inflammatory paradental cyst: A rare entity, occurring exclusively in mandibular molar area. • Lateral periodontal cyst: A developmental cyst occurring in premolar area of mandible and sometimes in maxilla. It may be mistaken for apical periodontitis. • Nonodontogenic incisive canal developmental cyst: Located centrally between maxillary incisors and may be mistaken for apical periodontitis if projected over the apex. • Simple bone cyst: Traumatic bone cyst. • Osseous/cemental dysplasia: Occurring in lower anterior region. Teeth are vital, there are no clinical symptoms. Radiographically can mimic chronic apical periodontitis. • Giant cell granuloma: Large multilocular, radiolucent area. • Hyperparathyroidism. • Odontogenic keratocyst. • Benign or malignant tumors of jaw. A mind-map to remember all points of RADIOGRAPHS is given in Figure 7.20.

Advanced Multiplanar Imaging: Cone Beam Computed Tomography (CBCT) for Endodontics It is digital advanced imaging that helps to obtain an image of virtually any plane through a structure that greatly improves diagnostic information of its 3-dimensional morphology. It involves section imaging. Axial, coronal and sagittal sections can be obtained with less patient exposure as compared to conventional CT scans. Cone beam computed tomography (CBCT) is a compact, faster and safer version of regular CT. The buccolingual dimension which cannot be appreciated on radiographs can be clearly visualized on CBCT images.

Applications of CBCT in Endodontics include: • Localization of canals (Fig. 7.21) • Assessment of root fractures (Figs 7.22A to C) • Evaluate the angulation of root (Fig. 7.23) and root resorption (Figs 7.24 and 7.25) • Periradicular pathologies in all planes can be evaluated. Example periapical or radicular cyst (Figs 7.26A and B).

STEP 3: DIAGNOSTIC TESTS Goals of Diagnostic Tests Ingle has stated 2 goals of diagnostic tests (Fig. 7.27). Diagnostic tests are important adjunctive tools in the decision-making process that leads to both pulpal and periapical diagnoses. Do not rely on a single diagnostic test result. If at least one more test gives similar findings, then the appropriate treatment is recommended.

Various Pulp Tests Pulp tests determine the pathological status of pulp.

Specific Pulp Tests • Thermal tests: – These tests identify the presence of pulp nerve tissue that is capable of responding to a change in temperature. – They may provide information that suggests whether the pulp is reversibly or irreversibly inflamed or necrotic. – The preferred temperature for heat test is 65.5oC (150oF). – It is important to isolate individual tooth with rubber dam while performing thermal tests to prevent any false positive results from the adjacent teeth. – Abnormal response to thermal tests is elicited as: - Lack of response to stimulus-Lingering or intensified pain sensation after removal of the stimulus - Immediate, excruciating painful sensation as soon as the stimulus is placed upon the tooth. Figure 7.28 shows heat test being performed using guttapercha stick.

Diagnosis and Diagnostic Aids in Endodontics

Fig. 7.20  A mind-map to remember all points of radiographs

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Fig. 7.21  CBCT image showing MB2 canal in a maxillary first molar tooth. (Courtesy of Dr Mansi Shah, Dentoview: Advanced Dental Imaging Center)

A

Fig. 7.23  CBCT image of a tooth with dilaceration. (Courtesy of Dr Mansi Shah, Dentoview: Advanced Dental Imaging Center)

B

C

Figs 7.22A to C  CBCT images showing horizontal root fracture of palatal root of maxillary second premolar tooth. (Courtesy of Dr Mansi Shah, Dentoview: Advanced Dental Imaging Center)

A Fig. 7.24  CBCT image showing blunting of apex caused due to external root resorption. (Courtesy of Dr Mansi Shah, Dentoview: Advanced Dental Imaging Center)

B

Figs 7.25A and B  CBCT image showing internal resorption in a tooth. (Courtesy of Dr Mansi Shah, Dentoview: Advanced Dental Imaging Center)

Diagnosis and Diagnostic Aids in Endodontics

A

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B

Figs 7.26A and B  CBCT image of a radicular cyst. (Courtesy of Dr Mansi Shah, Dentoview: Advanced Dental Imaging Center)

Fig. 7.27  Goals of diagnostic tests

– False negative response to heat test (pulp vital but no response) in cases of: - Recent trauma cases - Newly erupted teeth with immature apex due to incompletely developed Rashkow’s plexus) - Calcification present in the tooth – False positive response to heat test (pulp nonvital but positive response) in cases of: - Partially necrotic tooth with some vital tissue present - Inadequately dried tooth may give false-vital response - Or when there is contact with metal restorations causing conduction of current to periodontium. • Electric tests Purpose: It is a test for assessment of pulp vitality by gauging the ability of nerves in the pulp to respond to electric stimulation.

Response and Test Result

Fig. 7.28  Photograph showing heat test being performed using heated gutta-percha stick (Courtesy of Dr CR Suvarna)

Patient may feel a ‘warm’, ‘tingling’, ‘burning’ or pain sensation. This response is due to A-Delta nociceptors in pulp that do not transmit electric, thermal, touch or proprioceptive sensations to CNS, but only pain. A positive response indicates vitality of pulp. No response indicates nonvital pulp or necrosis of pulp.

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Procedure • Teeth to be evaluated are isolated and dried. • A control tooth (contralateral vital tooth) should be tested first in order to establish a baseline response and to help the patient know what a “normal” sensation is. • Dry contact with the tooth does not evoke a response. The tooth should be coated with a conductive medium to transmit current such as petroleum jelly, water-based jelly, toothpaste or prophylactic paste. • Optimal placement of probe tip is on the occlusal 2/3rd of labial or buccal surfaces of teeth or the incisal edges. • Once the probe tip is in contact with the tooth, the patient is asked to place the finger lightly on the metal part of the probe to complete the circuit and initiates the delivery of electric current to the tooth. • Patient is instructed to remove his/her finger from the probe handle when a warm, tingling sensation is felt. • The suspected tooth should be tested at least twice to confirm the results. • In case of complete coverage crown, a small metal Endodontic instrument such as files or explorers can be used as bridging instrument, with the tip coated with contact medium and placed on enamel or dentin of the tooth being evaluated. The probe tip is then placed on the metal of the bridging instrument. Figure 7.29 shows electric pulp test being performed using electric pulp tester.

Limitations • The response to electric pulp testing (EPT) does not reflect the histological health or disease status of the

• • • • •

pulp. It only denotes that some viable nerve fibers are present in the pulp that are capable of responding. The use of electric pulp tester in a patient with cardiac pacemaker can interfere with its function. So it is contraindicated in such patients. It may cause some anxiety in the patient knowing the instrument passes an electric current through their teeth. False-positive responses can also occur just as in thermal tests in adjacent teeth especially those with contacting metal fillings. This test is not reliable in younger teeth with immature apices or in teeth following a traumatic injury. It relies on subjective response by the patient and only measures the neurological status of pulp, not the vitality in true sense.

Cohen has given the following accuracy rate results of pulp tests: Cold test → 86% Electric test → 81% Heat test → 71% These usual pulp tests provide information only about the presence or absence of nerve receptors in the pulp and not about the pulpal blood supply. Methods to assess pulpal circulation: Assessment of pulpal circulation is more accurate determinant of pulp vitality as compared to thermal tests because it uses methods that are objective tests that help to differentiate between vital and necrotic pulp. Pulpal circulation can be assessed with the following methods: • Laser Doppler flowmetry • Pulse oximetry • Transmitted light-Photoplethysmography • Infrared thermography Laser Doppler Flowmetry and Pulse Oximetry are explained here.

Laser Doppler Flowmetry It is a method used to assess blood flow in microvascular system.

Fig. 7.29  Electric pulp test being performed using electric pulp tester (Courtesy of Dr CR Suvarna)

Doppler principle: This technology uses a beam of infrared (780 to 820 nm) or near infrared (632.8 nm) light, directed into the tissue by optical fibers. As light enters tissue, it is scattered by stationary tissue cells and moving red blood cells.

Diagnosis and Diagnostic Aids in Endodontics

According to the Doppler principle (Law of Light Frequency Shift) • The light beam will be frequency-shifted by moving red blood cells. • The light beam will remain unshifted as it passes through the static tissue. This average Doppler frequency shift will measure the velocity at which the red blood cells are moving.

Application of Laser Doppler Flowmetry (LDF) in Dentistry Laser Doppler Flowmetry can be used to assess pulpal blood flow. The initial use of LDF was exclusively for direct soft tissue blood flow measurements. But for dental situations, there is interference of hard tissues like dentin and enamel. If it is properly conducted: • It is found to be an accurate, reliable and reproducible method to assess pulpal blood flow and check vitality of tooth pulp. • It has been shown to work in primary incisors as well • It is very useful in cases of dental trauma • It can identify “at risk” teeth early after the trauma • In case of avulsion, it can detect revascularization after a few weeks and well in advance of other traditional clinical tests.

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Principle: It employs a light source probe that emits simultaneously two light beams: 1. One transmits red light (640 nm) 2. Other transmits infrared light (940 nm) • The light passes through the tissue of interest • A photodetector is placed on the opposite side of the light source to capture whatever light gets through • Oxygenated hemoglobin and deoxygenated hemoglobin absorb different amounts of red and infrared light. The machine calculates the difference between the light emitted and the light received to provide the pulse rate and oxygen concentration in blood.

Application in Dentistry Pulse oximetry has been tested and suggested to assess pulp vitality with mixed results. Some studies have found pulse oximetry test to have high accuracy rate while other studies showed that it does not have predictive diagnostic value for diagnosing pulp vitality. The technology uses devices that are too cumbersome and complicated, hence, not feasible for routine dental practice.

Requirements

SPECIAL TESTS

To ensure consistent and accurate reading, • The Laser Doppler flowmetry (light) probe tip should be placed on the same part of the crown. This requires a custom-made stabilizing stent that can be made easily out of rubber base impression material. • Prior to placing the stent, the gingiva should be covered with a dark dental dam or aluminum foil. • Patient should be on similar position in the dental chair each time while the recording is done.

Bite Test • When a patient presents with pain while biting and is unable to identify which tooth is sensitive to biting pressure, bite test may help to localize the tooth involved. • Causes of pain while biting:

Drawbacks • Initial high set-up cost • Accurate and consistent reading of LDF assessment requires certain critical steps to be taken • May not be feasible for routine dental practice. • Cannot be used if the tooth to be tested cannot be stabilized.

Pulse Oximetry It is a noninvasive and objective way to record the oxygen saturation of blood and pulse rate.

• Devices used for bite test: Cotton applicators, toothpicks, orangewood sticks, rubber polishing wheels. Tooth slooth is specifically designed to perform bite test. Figure 7.30 show bite test using cotton roll. Figures 7.31 and 7.32 show tooth slooth for bite test.

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Procedure • The small cupped-out area on the device is placed in contact with the cusp to be tested. • The patient is asked to slowly but firmly apply biting pressure with opposing teeth to the flat surface on the opposite side of the device until full closure is achieved. • After a few seconds, patient is then asked to release the pressure very quickly. Each individual cusp on a tooth is tested in this manner. • The clinician notes whether the pain is elicited. – During pressure phase or – Upon quick release of pressure Pain upon release of biting pressure frequently indicates fractured cusp or cracked tooth. Fig. 7.30  Bite test using cotton roll (Courtesy of Mr Amar, Dr Dabholkar’s clinic)

Fig. 7.31  Tooth slooth (Courtesy of Dr CR Suvarna)

Staining and Transillumination

• A small amount of dye is coated onto the crown/root with a small cotton pellet.   Figures 7.33 and 7.34 show caries detector dye and staining test respectively. • Remaining dye on the surface is washed away or removed with a moist application of 70% isopropyl alcohol. If fracture or crack is present, dye remains in that crack line and can be observed through magnifying loupes or dental operating microscope.

Transillumination

Fig. 7.32  Bite test being performed with tooth slooth in place. Tooth slooth should make contact with the cusp tips (Courtesy of Dr CR Suvarna)

• Applications: – To determine the presence of a crown or root fracture – Detection of caries, calculus and soft tissue lesions – Aid in determination of pulp vitality • Devices used: – Specifically designed fiberoptic lights – High speed handpiece with fiberoptic activated or other bright point light sources. Figure 7.35 show the fiberoptic light source for transillumination test as demonstrated in Figure 7.36.

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• Procedure: The dental unit light should be turned off and only the fiberoptic light used.

Fig. 7.34  Staining test being performed on mandibular first molar (Courtesy of Dr CR Suvarna)

Anesthetic Test • When other diagnostic tests have been inconclusive, then selective anesthesia may be helpful to locate the offending tooth or the arch and to derive the appropriate diagnosis. • Administration of the local anesthesia could be by infiltration, block or intraosseous injection. • When the patient is unable to determine which arch the pain is coming from then a periodontal ligament

Fig. 7.33  Caries detector dye (Courtesy of Dr CR Suvarna)

Fig. 7.35  The fiberoptic light source for transillumination test (Courtesy of Dr CR Suvarna)

Fig. 7.36  Demonstrating transillumination test (Courtesy of Dr CR Suvarna)

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injection (Intraligamentary) can be administered starting from the most posterior tooth in the quadrant, one tooth at a time, until the pain is eliminated. This is done first in the maxillary arch. If after appropriate period of time, the pain does not get eliminated, the technique is repeated for the mandibular teeth. • When a patient reports vague location of pain such as discomfort over entire left cheek, and associated hard and soft tissues, if a diagnostic left inferior alveolar block remits the pain, the pathosis can be attributed within the distribution of inferior alveolar nerve and its branches. If the pain does not remit, and remains constant, then cardiac pain or pain from myocardial infarct can be suspected which might have referred to the left mandible and mimics pain of dental or orofacial origin. • If the patient is unable to locate an individual tooth or arch, but the clinician feels that pain may be from posterior maxillary quadrant, infiltration anesthetic test may be used for each tooth starting from most posterior tooth. If the pain remits, the source of pain is identified but if the pain does not remit, the clinician may suspect the pain source to be in mandibular arch and now administer mandibular block with an assurance that pain should abate. If the pain still remains, the clinician can conclude that the pain is not of Endodontic origin and do further evaluation.

Tracing of Intraoral Sinus Tract An infection from a tooth draining through an intraoral communication to the gingival surface is known as ‘sinus tract’. When it becomes lined with epithelium, it is termed as ‘fistula’. Sinus tract facilitates drainage of infectious exudates, as a result, a periapical infection with an associated sinus tract is not generally painful. Sinus tract can be a useful objective diagnostic aid to trace the origin of infection. This test is done with a fine Guttapercha point. The GP cone is inserted through the opening of the sinus tract until the resistance is felt. Then an intraoral periapical radiograph is exposed. The radiograph is viewed to determine the path taken by Guttapercha cone and the point of termination of sinus tract. This helps to locate the offending tooth and specifically the offending root (Refer to figures 5.9 and 5.10 for the photograph and radiograph respectively of tracing of intraoral sinus tract). Once the etiology of sinus tract is eliminated, the sinus tract closes within a few days.

Test Cavity • Test cavity method allows one to determine pulp vitality. But is seldom used today. • It is performed only when other diagnostic tests have been inconclusive and the clinician has a high level of suspicion that the pulp is necrotic. • Patient is informed about the exact procedure and the reason why it is being done. • Patient is not anesthesized during this procedure. • This test involves use of #1 or # 2 round bur at high speed with proper air and water coolant for drilling in the tooth to remove enamel and about half of the total thickness of dentin. If sensitivity is experienced beyond the dentino­ enamel junction, it signifies that there is some viable tissue remaining in the pulp, not that the pulp is totally healthy. The procedure is terminated and the tooth is restored. If there is absolutely no pain or sensation during cavity preparation, until the pulp chamber is reached, it is a good indication that the pulp is necrotic and root canal treatment is indicated. • Reliability of this test is questionable as: – A tooth with calcification causing pulpal obliteration may not give clear results – Gangrenous or inflammed pulp can give false results.

Other Tests • Ultraviolet light: It can be used to determine the pulp vitality. When exposed to UV light, the teeth with necrotic pulps and teeth with Endodontic treatment did not fluoresce. When exposed to UV light, the teeth with vital pulps fluoresce normally (The property of the objects to emit light of higher wavelength when illuminated with ultraviolet (UV) light is called fluorescence). UV light can be harmful to eyes. So the patient and the staff should wear protective eyewear (goggles). To view the color changes in the tooth clearly, the operating light needs to be suppressed. • Measurement of tooth surface temperature: – Measurement of crown surface temperature may determine whether vital tissue or necrotic tissue fills the pulp chamber. – Cholesteric liquid crystals at a temperature of 30–40oC range are used for this purpose. – When applied to the tooth surface the crystals undergo color changes that are compared with adjacent or contralateral teeth.

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PULPAL DIAGNOSIS Simplified chart that will direct your thinking process to correct clinical diagnosis Clinical subjective and objective findings

• No spontaneous symptoms • Respond to pulp tests • Symptoms/ response to pulp tests are mild that do not cause distress • Transient sensation, reverses in seconds

• Presence of caries, exposed dentin, recent dental treatment, defective restorations • Stimulation with an irritant causes symptoms, but its removal resolves symptoms

• Sometimes deep caries but asymptomatic • Intermittent or spontaneous pain • Stimuli causing temperature changes (Especially cold) elicit heightened and prolonged episodes of pain even after removal of stimulus • Pain may be sharp, or dull, localized or referred

• Asymptomatic • No response to electric pulp tests or to cold stimulation • May respond to heat • Multirooted teeth: sometimes roots may give confusing symptoms, one root responds, other does not • Tooth may become very hypersensitive to heat

• Symptoms of pain (spontaneous) • No response to electric pulp tests or cold tests • May respond to heat • Pain on percussion • Tooth may become very hypersensitive to heat

Radiographic findings

• No evidence of • No significant resorption, caries radiographic change or pulp exposure • Calcification may or may not be present

• Minimal changes in radiographic appearance of periradicular bone • Thickening of PDL • Extensive canal calcification in response to pulpal irritation • Deep restorations, caries, exposure may be evident ↓

• Deep caries • Thickening of PDL • Pulpal involvement

• Thickening of PDL space • Periapical radiolucent lesion

Diagnosis

Indicates normal pulp

Indicates reversible pulpitis

Indicates irreversible pulpitis

Partial or complete pulp necrosis

Pulp necrosis with periapical lesion

Treatment plan

No treatment

• Requires palliative treatment according to cause • Remove etiologic factors

• Root canal treatment

• Root canal treatment

• Root canal treatment

↓

↓

↓

↓

PERIAPICAL DIAGNOSIS Clinical

• Very painful response to biting pressure or percussion • May or may not respond to pulp vitality tests ↓

• No clinical symptoms • No response to pulp vitality tests • Tooth not sensitive to biting pressure, but some different sensation may be felt on percussion ↓

• Very painful to biting pressure, percussion and palpation • Not respond to any pulp vitality tests • Mobility of various degrees may be present • Swelling may be present in mucobuccal fold • Febrile, lymph nodes may be tender on palpation

• No clinical symptoms • No response to pulp vitality tests • Tooth not sensitive to biting pressure but “feels different” upon percussion • Intermittent drainage through an associated sinus tract

Radiographic findings

• Widened PDL space but not periradicular radiolucency. ↓

• Periradicular radiolucency, usually around apical third of root ↓

• Can exhibit anything from a widened PDL space to a periradicular radiolucency

• Periradicular radiolucency present

Diagnosis

Acute periradicular/ apical periodontitis

Chronic periradicular/ apical periodontitis

Acute periradicular/apical abscess

↓

↓ Chronic periradicular/apical abscess (suppurative)

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Fig. 7.37  A mind-map to remember all points of diagnostic tests

Diagnosis and Diagnostic Aids in Endodontics

– Thermistors are found to be consistent in recording the surface temperatures of teeth with both vital and necrotic pulps. – Electronic thermography can determine the relative differences in temperature in both superficial and deep areas and it can be a useful adjunct to other pulp diagnostic tests. A mind map to remember all point of diagnostic tests is given in Figure 7.37.

STEP 4: ARRIVING AT AN ACCURATE ENDODONTIC DIAGNOSIS After thorough questioning, examination and testing, the various subjective, objective, clinical testing and radiographic findings are considered for decision-making process to arrive at an accurate diagnosis. The clinical judgment for decision-making is influenced by various factors such as: • Knowledge and skills: Developed by education and training. • Clinical experience: With experience of various cases over a period of time, clinician develops the judgment to correlate various findings and come to a definite conclusion in a short time. • Updating information: Keeping abreast with the latest trends in the field: – by reading appropriate literature and – Attending continuing education courses

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• Clinician’s attitude: Clinician must have the attitude of considering each and every patient ‘important’ and give his full attention and expertise in treatment.

Diagnosis Some cases may be straight forward, where, the findings clearly point towards the diagnosis. In few cases, a list of differential diagnosis is made and then based on reasoning and clinical judgment, a definitive diagnosis is derived by exclusion. Few cases may present a diagnostic challenge, where an obvious dental etiology cannot be found. An existing medical problem or a nonodontogenic cause should be  suspected and looked for and appropriate referral be made to protect the patient from unnecessary dental treatment. The pulpal and periapical diagnosis is made based on the findings and appropriate reasoning to determine whether the case requires Endodontic treatment or not. A simplified chart that directs your thinking towards an accurate pulpal and periapical diagnosis to formulate the necessary treatment plan is given on page number 127.

BIBLIOGRAPHY 1. Cohen S, Hargreaves KM. Pathways of Pulp, 9th edn. St. Louis: Mosby, 2006. pp.2-39. 2. Grossman L, Oliet S, Del Rio C. Endodontic Practice, 11th edn. Varghese publication, 1991. pp.1-18. 3. Ingle J, Bakland L, Baumgartner J. Ingle’s Endodontics, 6th edn. BC Decker Inc, Hamilton, 2008. pp.520-637.

CHAPTER

8

Rationale of Endodontic Therapy

This chapter tells you about the logic behind doing Endodontic therapy.  You must know • Which were the Proposed Theories of Spread of Infection that Developed into Modern Philosophy of Endodontics? • How do Dental Biologic Tissues React to Noxious Stimuli? • Why is Inflammatory Response of Pulp Different from other Parts of Body? • What Tissue Changes Occur during Inflammation? • What Tissue Changes Occur following Inflammation? • What is Role of Immunity in Endodontics? • What are the Zones of Reaction of Periradicular Tissues and What are Endodontic Implications?

WHICH WERE THE PROPOSED THEORIES OF SPREAD OF INFECTION THAT DEVELOPED INTO THE MODERN PHILOSOPHY OF ENDODONTICS? Focal Infection Theory (FIT): An Obsolete Concept Now In 1891, WD Miller published a report, entitled as “Human mouth as focus of infection”. He used Robert Koch’s postulates to establish microbial etiology of infectious diseases. He concluded that mouth was a focus of infection and that the bacteria in mouth caused various systemic diseases. In 1909, Dr William Hunter identified  oral sepsis as a cause of systemic diseases. Later Billings described the terms focus of infection and focal infection and the term oral sepsis was replaced by focal infection. A focus of infection is described as a confined area that contains pathogenic microorganisms, that can occur anywhere in the body and usually causes no clinical manifestations. A focal infection is a localized or generalized infection caused by the dissemination of microorganisms or toxic products from a focus of infection.

According to the Focal Infection Theory, the  focus of infection is often unrecognized, while secondary infections might occur at sites particularly susceptible to such microbial species or toxins such as gallbladder, kidney, liver, prostate; but most commonly oral tissues. In 1920s, Dr Weston Price presented a research suggesting that the bacteria entrapped in the dentinal tubules during Endodontic treatment could leak and lead to systemic diseases such as arthritis, diseases of kidney, heart, nervous, gastrointestinal, endocrine and other systems. Dr Price advocated tooth extraction over Endodontic treatment. It resulted in era of tooth extraction both for treatment of systemic disease and as a prophylactic measure against future illness. The Focal Infection Theory led to needless extraction of millions of Endodontically treated teeth until well-designed studies conducted during 1930s demonstrated that this theory was not valid. Dr Price’s research techniques were criticized as they lacked many aspects of modern scientific research, including absence of proper control groups and induction of excessive doses of bacteria. In 1940, Reiman and Havens stated that the suggested focal infection theory has not been proved. The infectious

Rationale of Endodontic Therapy

agents involved were not known patients whose teeth or tonsils were removed, often continue to suffer from the original disease.

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Flow chart 8.1  Reaction of dental biologic tissues to noxious stimuli

Mechanism of Focal Infection Two generally accepted mechanisms in production of focal infection (Shafer’s Textbook of Oral Pathology, 7th edn. p.512): 1. Metastasis of microorganisms from an infected focus by either hematogenous or lymphogenous spread. 2. Toxins or toxic products may be carried through the bloodstream or lymphatic channels from a focus to a distant site where they may result in a hypersensitive reaction in the tissues. Oral foci of infection: The theoretical sources of infection that may set-up distant metastases include: a. Teeth with infected root canals or infected periapical lesions such as periapical granuloma, cysts or abscesses; b. Transient bacteremia that is found to occur after tooth extraction or after manipulation of gingiva related to severity of periodontal disease.

• Pulp is an organ of terminal and limited circulation • Pulp has no efficient collateral circulation.

HOW DO THE DENTAL BIOLOGIC TISSUES REACT TO NOXIOUS STIMULI?

WHAT ARE THE TISSUE CHANGES THAT OCCUR DURING INFLAMMATION?

Various noxious stimuli that can affect the dental biologic tissues (Bacterial, Physical, Chemical, etc.) and the reaction of the dental pulp to these stimuli have been explained in detail in Chapter 4 ‘The Pulpal Reactions to Caries and Dental Procedures’. Such stimuli can result in reversible or irreversible changes in the pulp and the periradicular tissues as listed in Flow chart 8.1. The changes that occur in the pulp and the periradicular tissues are mediated by a series of inflammatory and immunological reactions in order to eliminate the irritant and repair any damage, which will be explained in detail in this chapter.

Inflammation: Basic Concepts

WHY IS THE INFLAMMATORY RESPONSE IN CONNECTIVE TISSUE OF DENTAL PULP DIFFERENT FROM OTHER PARTS OF BODY? Pulpal inflammatory response is modified due to following reasons: • Pulp is encased within the hard tissues • Pulp has limited space to expand during inflammation • Pulp has limited portals of entry

• Inflammation is local physiologic reaction of body to an irritant or noxious stimulus. • Object of Inflammation → to Remove the irritant (R2) → to Repair damage to the tissue • Type of inflammation Predominant cells – Acute and early stages PMN neutrophils of inflammation – Chronic inflammation Lymphocytes, plasma cells, monocytes, macrophages • Cardinal symptoms of inflammation: – Pain (dolor) – Swelling (tumor) – Redness (rubor) – Heat (color) – Disturbance of function (Functio lesea). In an inflamed pulp, all these symptoms occur, but only pain and disturbance of function are recognized clinically. In case of acute inflammation of periradicular tissues, all the cardinal symptoms may be recognized clinically.

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Inflammatory Cells 1. Polymorphonuclear neutrophils (PMNs): – Present during acute or early stages of inflammation – Function: To phagocytise bacteria and lyse fibrin and cellular debris and engulfment of antigen-antibody complexes and nonmicrobial material. – PMNs are attracted to the area of inflammation by chemotactic factors produced by bacteria or by complement. – They are the first cells to migrate from the vessels. – Serum factors of complement and immunoglobulins called opsonins bind bacteria to surface of PMNs. – PMNs have narrow life span. They are destroyed in the inflammatory site when pH of tissue fluids becomes less than 6.5. Destruction of PMNs ↓ Release of proteolytic enzymes, pepsin and cathepsin ↓ Tissue lysis ↓ PMNs along with products of cellular lysis and debris constitutes the pus. 2. Macrophages: – Derived from circulating monocytes – At the site of inflammation, in extravascular areas, immature monocytes differentiate into macro­ phages. – Function: They are phagocytic cells that ingest cellular debris, microorganisms and particulate matter. They enhance the immunologic reaction by ingesting, processing and degrading antigen before presenting to lymphocytes, thus causing repair. – Macrophages secrete mediators of inflammation such as lysosomal enzymes, complement proteins and prostaglandins. – Monophages are mononucleated cells that fuse with other macrophages to produce multinucleated giant cells. 3. Lymphocytes: – Appear in chronic stage of inflammatory reaction. – Two types: T-lymphocytes and B-lymphocytes, both derived from pluripotential hemopoetic stem cells. Stem cells carried to thymus, where they become immunologically competent T-cells whereas B-cells tend to become immunocompetent in the bone marrow. • T-lymphocytes: – T-lymphocytes have long lifespan – Found in paracortical areas of lymph nodes – Responsible for cell-mediated immunity.



– T-lymphocytes stimulated by an antigen. Sensitized lymphocyte can have following manifestations: i. Memory T-cells: They speed the immun­ ologic reaction in subsequent encounters with same antigen ii. Helper/Suppressor T-cells: Stimulate or suppress development of effector T- or B-cells iii. Effector T-cells: Cell-mediated immunity such as delayed hypersensitivity. – Sensitized lymphocyte release chemical mediators: Lymphokines may activate macro­ phages, polymorphonuclear leukocytes and non-sensitized T-cells. Lymphokines may produce interferon, that inhibits viral replication as needed by immune response. • B-lymphocytes: – Shorter lifespan than B-cells – Found in cortical areas of lymph nodes – When activated, B-cells become larger cells called plasmablasts. Plasmablasts divide into: i. Memory B-cells: They speed the immun­ ologic reaction in subsequent encounters with same antigen. ii. Plasma cells: Large, oval or round cells with eccentric nuclei containing chromatin in cart-wheel form. Plasma cells produce immunoglobulins: IgG, IgA, IgM, IgE and IgD (Remember: GAMED) which are involved in different defense reactions such as: a. Neutralization of bacterial toxins by antitoxins b. Coating of bacteria with antibodies or opsonization for phagocytosis c. Lysis of bacteria by complement activation d. Agglutination of bacteria e. Combining of antibody with viruses to prevent their entry into cells. – Responsible for humoral immunity. 4. Eosinophils, basophils, mast cells are also found in the pulp and periradicular tissues. – Eosinophils mainly found in allergic reactions and parasitic reactions. – Function : Phagocytosis of antigen-antibody complexes and detoxification of histamine. – Basophils and mast cells are the same with basophils found in hemopoetic system and mast cells found in tissue.

Rationale of Endodontic Therapy

– Both basophils and mast cells contain granules and when stimulated, by injury they degranulate and release chemical mediators such as histamine (vasodilator) and heparin (anticoagulant). They can initiate inflammatory allergic responses.

Inflammatory Mediators The main biologic function of inflammatory mediators is to cause vasodilatation and increased vascular permeability and recruit inflammatory cells, mainly neutrophilic leukocytes and macrophages from blood circulation to the site of tissue injury. The inflammatory reactions are mediated by chemical substances produced by certain cells or present in plasma.

Nonspecific Inflammatory Mediators I. Cell derived mediators: 1. Vasoactive amines such as histamine, serotonin (5-Hydroxytryptamine) 2. Lysosomal enzymes 3. Neuropeptides 4. Cytokines 5. Nitric oxide 6. Eicosanoids. II. Plasma derived mediators 1. Complement system 2. Kinin system 3. Coagulation and fibrinolytic system.

Specific Inflammatory Mediators: Antibodies I. Cell derived mediators: 1. Vasoactive amines such as Histamine, Serotonin (5-Hydroxytryptamine): Histamine is released by mast cell degranulation in response to variety of stimuli such as physical injury, immune reactions involving binding of antibody to mast cell, etc. Histamine causes dilatation of arterioles and increased vascular permeability of venules. Serotonin is present in platelets and enterochromaffin cells. Its release is stimulated when platelets aggregate after contact with collagen, thrombin, antigen-antibody complexes. It causes increased vascular permeability. 2. Lysosomal enzymes: Collagenase can mediate tissue injury by degrading collagen and other tissue proteins. Kallikerin released from the lysosomes promotes the generation of bradykinin. Lysosomal enzymes cause increase in vascular permeability and play a role in activation of the complement system.

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3. Neuropeptides: Neuropeptides such as Substance P, Calcitonin-gene related peptide (CGRP) are potent vasodilators. Increased production and release of neuropeptides plays an important role in initiating and propagating the inflammation of the pulp. 4. Cytokines: They are polypeptides produced by many cell types that play a role in modulating the function of other cell types. These include Interleukin-1, Interleukin-8 and tumor necrosis factor (TNF). IL-1 and TNF are produced by activated macrophages. They induce the synthesis and surface expression of the endothelial adhesion molecules and bring about enhanced leukocyte adhesion to endothelial walls. IL-1 has been found mainly in periapical pathology and IL-8 is associated with acute apical periodontitis. TNF is associated with chronic apical lesions and root canal exudates. IL-1 and IL-8 are proinflammatory cytokines and TNF is a chemotactic cytokine. 5. Nitric oxide: Nitric oxide in macrophages act as free radicals, which are cytotoxic to certain microbes and tumor cells. It increases vascular permeability and causes inactivation of anti-proteases. 6. Eicosanoids such as prostaglandins or leukotrienes are released through the cyclooxygenase pathway and lipooxygenase pathway in response to injury to cells, which are involved in inflammatory process. II. Plasma derived mediators: 1. Complement system: It consists of 20 component proteins and their cleavage products found in greatest concentration in plasma. Components of complement system such as C3a, C3b, C5a, C5b, C5-C9 are products of the complement cascade, which can be activated by two pathways: The classic pathway and the alternate pathway. The classic pathway is initiated by activation of C1 by multimolecular aggregates of IgG or IgM antibody complexed with specific antigen and the alternate pathway is activated by microbial cell components (lipopolysaccharide, teichoic acid) and plasmin. C3a and C5a causes vasodilation and increases the vascular permeability and C5a is a powerful chemotactic agent for neutrophils, monocytes, eosinophils and basophils and causes increased adhesion of leukocytes to endothelium. 2. Hageman factor activated Kinin and Coagulation system: Kallikrien converts kininogen into bradykinin, which in turn converts plasminogen into plasmin. Kinins cause increased vascular permeability, vasodilation and smooth muscle contraction. Coagulation/Clotting system and fibrinolytic system: Its two components: Fibrinopeptides which

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increase vascular permeability and are chemotactic for leukocytes and thrombin which increases leukocyte adhesion and fibroblast proliferation.

Vascular Changes 1. Vasodilatation: Induced by histamine, prostaglandins, nitric oxide. 2. Increased vascular permeability: Vasoactive amines, C3a, C5a, Bradykinin, Leukotrienes, Platelet activation factor play a role in it. It causes increase in concentration of red cells in small vessels. Increase in viscosity of blood causes slower flow of blood. 3. Leukocyte accumulation and migration. Tissue changes that occur in dental biologic tissues during inflammation are summarized in Flow chart 8.2.

Correlation between Clinical and Histologic Findings Clinical diagnosis of inflammatory pulpal or periapical disease is mainly based on clinical signs and/or symptoms,

duration of disease, pulp tests, percussion, palpation and radiographic findings whereas histologic diagnosis is a morphologic and biologic description of cells and extracellular matrix of diseased tissues. Clinical diagnosis represents provisional diagnosis based on signs, symptoms and testing results whereas histologic diagnosis is a definitive diagnosis of diseased tissue. There is no good correlation between clinical symtoms and histopathologic findings of pulpitis and apical periodontitis. For example, a pulp tissue with acute pulpal abscess at cellular level may be clinically completely asymptomatic. Also, many teeth with apical periodontitis histologically are clinically asymptomatic.

Correlation between Radiographic and Histologic Findings Radiography detects pathologic changes at tissue level, not cellular levels. Even by using very sensitive imaging systems such as cone beam computed tomography (CBCT),

Flow chart 8.2  Changes in dental biologic tissues during inflammation

Rationale of Endodontic Therapy

ultrasound and other technologies, it is impossible to detect the presence of inflammatory changes in pulp and periradicular tissues. Sometimes the tooth with inflammation of periradicular tissues observed histologically might have normal radiographic features. This is because the lesions localized in the cancellous bone may not be visible radiographically unless they involve cortical bone. In addition, radiographic findings may not be able to predict asymptomatic apical periodontitis (granuloma) from asymptomatic apical periodontitis with cyst formation (radicular cyst). There is poor correlation between radiographic and histopathologic findings of inflammation or disease of periradicular tissues.

WHAT TISSUE CHANGES OCCUR FOLLOWING INFLAMMATION? Tissue changes that occur following inflammation are summarized in Flow chart 8.3. Same substance can act as stimulant and irritant. For example: Calcium hydroxide. In the center of inflammatory area, strong irritant causes degeneration/destruction. At the periphery, mild irritant causes proliferation.

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WHAT IS THE ROLE OF IMMUNITY IN ENDODONTICS? Two types of immune responses are involved when there is infection or inflammation in the pulp and the periradicular tissues: innate immunity and adaptive immunity. The immune cells present in human periradicular lesions include lymphocytes, macrophages, plasma cells, neutrophils and natural killer cells (NK). 1. Nonspecific innate immune response: The primary nonspecific innate immune defense mechanism in response to apical periodontitis is phagocytosis of microbes by specialized phagocytes such as PMNs and macrophages. Inflammation of tissue causes recruitment of PMNs from the blood circulation into periradicular tissue. Activated PMNs cause an abrupt increase in oxygen consumption (respiratory burst), resulting in release of oxygen radicals that destroy microbes. Phagocytosed microbes or foreign particles are exposed to a very toxic environment that contains specific and azurophilic granules and oxygen radicals and are eventually degraded.

Flow chart 8.3  Changes in dental biologic tissues following inflammation

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2. Adaptive/Specific immune response: The specificity of adaptive immune response is regulated at genetic level in B and T lymphocytes through a complex process that leads to generation of molecules, which are specific receptors on T-cells and B-cells. These molecules recognize and bind to foreign or self-antigens. The T-cell antigen receptors on T-cells interact with antigens that are presented by MHC molecules along with accessory molecules. The B-cell antigen receptors, also called as immuno­ globulins interact with antigens directly. They may be secreted in the blood circulation or in the tissues as antibodies.

Fish’s Zones of Reaction: ICIS Zones of Infection, Contamination, Irritation, Stimulation.

Implications • Root canal is a seat of infection. • Microorganisms in root canal are rarely motile and will not move into periradicular tissues by themselves.

WHAT ARE THE ZONES OF REACTION OF PERIRADICULAR TISSUES AND ENDODONTIC IMPLICATIONS? Fish performed an experiment to study the reaction of the periradicular tissues to noxious products of tissue necrosis, bacterial products and antigenic agents from root canal. In the experiment, he established an experiment foci of infection in the guinea pigs by drilling openings in the jaw bone and packing it with wool fibers saturated with a broth culture of microorganisms. He described four zones of reaction surrounding foci of infection as shown in Figure 8.1. Table 8.1 gives the details of each of the zones of reaction.

Fig. 8.1  Diagram showing the four zones of reaction: (a) Infected/ Necrosed pulp; (b) Zone of infection; (c) Zone of contamination; (d) Zone of irritation; (e) Zone of stimulation as described by Fish

TABLE 8.1  Zones of reaction Zone of infection

Zone of contamination

Zone of irritation

Zone of stimulation

PMN leukocytes

Round cell infiltration and lymphocytes

Macrophages and osteoclasts

Fibroblasts and osteoblasts

Microorganisms are found

Around central zone, cellular destruction caused by toxins discharged from central zone is seen

Small round cells, normal bone cells and osteoclasts could just survive

Toxins are too diluted and mild enough to act as stimulant

Infection is present in the center of the lesion. Thus, root canal is seat of infection

In this area, bone cells die due to toxins, undergo autolysis. So, lacunae appear empty

Toxins become diluted

Collagen fibers are laid down by fibroblasts which act as wall of defense around zone of irritation. It also acts as scaffolding, on which the osteoblasts built new bone in an irregular fashion

Macrophages digest collagen and osteoclasts attack bone tissue, as a result of which a GAP is opened up in the bone around center of lesion, which is then filled with PMN leukocytes. Histologically, activity preparatory to repair is seen

A granuloma may be found or if epithelial rests of malassez are stimulated, a cyst will form

When microorganisms multiply or produce byproducts, they reach periradicular area

Rationale of Endodontic Therapy

A

B

C

D

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Figs 8.2A to D  Enlarged view of the lower left side of panoramic radiograph (OPG); (A) Preoperative view showing large area of rarefaction in relation to mandibular canine and mandibular second premolar; (B) Postoperative view after doing Endodontic treatment in mandibular second premolar and Endodontic retreatment in mandibular canine; (C) One-year follow-up view shows resolution of radiolucency to a great extent; (D) Two-year follow-up view shows further improvement and return of periradicular tissues to the normal (Courtesy of Dr Ajay Bajaj)

Flow chart 8.4  Fate of microorganisms in periradicular area



However, microorganisms may multiply sufficiently to grow out of root canal or the metabolic or toxic products of microorganisms may be diffused to periradicular area. • In the periradicular area: (Flow chart 8.4) • At the periphery of destroyed area, granuloma or cyst forms as shown in Flow chart 8.5. • When root canal therapy is done, the reservoir of microorganisms and their toxic products is eliminated, followed by obturation of root canal system to produce a three-dimensional hermetic seal, the destroyed periapical bone will undergo repair. Fish’s theory is the basis for successful Endodontic treatment.

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Flow chart 8.5  Lesion formed as per stimulant

Rationale of Endodontic Therapy • Effective elimination of the reservoir of microorganisms and their toxins from the root canal system by means of: – Unobstructed straight-line access to the apical part of the root canals. – Thorough instrumentation of root canals combined with irrigation (cleaning and shaping). • Well cleaned and well-shaped root canal is obturated to produce a three-dimensional hermetic seal which: – Prevents entry of microorganisms or fluids from root canal to periapical area or vice-versa (apical leakage). – Seal the remaining irritants in canal, i.e. entombment of residual bacteria. • The Endodontically treated tooth is protected by quality coronal restoration to prevent bacterial contamination. (coronal leakage).



Access cavity preparation and optimum cleaning and shaping of root canals eliminates the reservoir of bacteria or noxious products. Obturation of the wellcleaned and well-shaped root canal system followed by good post-Endodontic coronal restoration seals the tooth against leakage from oral fluids and bacterial contamination. As a result, the destroyed periapical bone undergoes repair and the area of rarefaction that was seen radiographically gradually resolves and disappears. Figures 8.2A to D show portions of the panoramic radiographs taken preoperatively, post-treatment, and follow-up after one and two years of a case in which Endodontic treatment has been successful and has resulted in the repair of periapical bone. The huge area of rarefaction that is seen in preoperative view has resolved and almost disappeared in the follow-up radiographs taken after one and two years respectively.

BIBLIOGRAPHY 1. AAE Fact Sheet on Focal Infection Theory. 2. Grossman L, Oliet S, Del Rio C. Endodontic Practice, 11th edn. Varghese publication; 1991.pp.116-25. 3. Hargreaves KM, Cohen S. Pathways of Pulp, 10th edn. Mosby Elsevier, St Louis, MO; 2011.pp.532-5. 4. Indramohan J, Karthika B, Mohiddin G. Myth of Endodontics in oral focal infection. Indian Journal of Multidisciplinary Dentistry. 2011;2(1):380-2. 5. Rajendran R, Sivopathasundharam B, Shafer’s Textbook of Oral Pathology, 7th edn, Elsevier Publication; 2012.p.512.

CHAPTER

9

Case Selection and Treatment Planning

This chapter describes thorough evaluation of a patient who has come for dental treatment. It will help you to make a decision whether to do or not to do root canal treatment in a particular case and guides you to formulate an effective Endodontic treatment plan to carry out the procedure.   You must know • How to Evaluate a Case for Treatment? • What are the Factors to be Considered for Case Selection for Root Canal Treatment? • What are the Indications and Contraindications of Root Canal Treatment? • How to Develop an Endodontic Treatment Plan? • How to Assess Difficulty of an Endodontic Case?

HOW TO EVALUATE A CASE FOR TREATMENT? Each case must be evaluated thoroughly before commencement of treatment. Proper evaluation of the patient for treatment includes: • Evaluation of medical condition of patient • Psychological evaluation • Dental evaluation.

Evaluation of Medical Condition of Patient Most of the medical conditions do not contraindicate Endodontic treatment. There are few systemic conditions that can influence the course of treatment and will require specific modifications. So, it is necessary to evaluate the medical condition of the patient before we plan to do root canal treatment (RCT). Physical status classification for patients given by American Society of Anesthesiologists (ASA): ASA I: Normal, healthy patient. No dental management alterations required. ASA II: A patient with mild systemic disease that does not interfere with daily activity or who has significant health risk factor such as smoking, obesity, etc.

May or may not need dental management alterations. For example, stage I or II hypertension, type II diabetes, allergy, well-controlled asthma. ASA III: A patient with moderate to severe systemic disease that is not incapacitating but may alter daily activities, may have significant drug concerns, may require special patient care. Would generally require dental management altera­tions. For example, stage III hypertension, type I diabetes, unstable angina pectoris, recent myocardial infarction, poorly controlled congestive heart failure, AIDS, COPD, hemophilia. ASA IV: A patient with severe systemic disease that is constant threat to life; definitely requires dental management alterations; best treated in special facility. For example, kidney failure, liver failure, advanced AIDS. The ASA classification is a useful guide for preoperative assessment of relative risk involved in treating a patient. If the patient has a systemic disease, under certain circum­stances, consultation with the patient’s physician may be necessary.

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Certain medical conditions that may influence Endodontic treatment planning [Remember ABCDE CAP]: Medical condition Precautions to be taken and treatment modifications 1. Allergy:

• If patient gives history of known allergy to a particular agent such as certain drugs, LA, latex gloves, etc. avoid using those agents that the patient is allergic to. • Always keep an emergency kit available in case of an unknown allergy. While designing an emergency drug kit, following drugs should be included as minimum: (As per ADA Council on Scientific Affairs, 2002): 1. Epinephrine 1:1000 (Injectable) 2. Histamine blocker (Injectable) 3. Oxygen with positive pressure administration capability 4. Nitroglycerin (Sublingual tablet or aerosol spray) 5. Bronchodilator (Asthma inhaler) 6. Sugar 7. Aspirin 2. Bleeding • Consultation with the patient’s   disorders: physician • Evaluate patient’s recent blood test report for bleeding time, clotting time • Use of antibiotic prophylaxis may be required. 3. Cardiovascular • Consultation with the patient’s   diseases: physician • Such patients are vulnerable to emotional stress. Reassurance and effective pain control is very important to manage the stress. • Patient with a history of myocardial infarction within past 6 months should not have elective dental care. • Use of vasoconstrictor (Adrenaline) in the local anesthetic should be considered. Sometimes plain LA, i.e LA without adrenaline may have to be used. • Patients with congenital heart disease and valve defects must be given prophylactic antibiotics prior to Endodontic treatment to prevent bacterial endocarditis.



• Pat i e nt s o n m e d i c at i o n s f o r hyper­­tension should also have their blood pressure measured prior to treatment. 4. Diabetes: • Consultation with patient’s physician may be required. • Evaluate blood glucose levels. • Before dental appointment, patient is asked to have his/her regular dose of insulin and normal meals. • Antibiotics may have to be prescribed in certain cases. • Patients with controlled diabetes and without any medical complications can receive the Endodontic treatment without any treatment modification. But a modified treatment plan is indicated for diabetic patients with medical complications. 5. End-stage renal • Endodontic treatment may have to   disease: be provided in a hospital setting to restore oral health and prevent infection. 6. Cancer: • Patients who are on chemotherapy or radiation therapy to head and neck may have impaired healing response. • Consultation with patient’s physician. • Whether to do extraction or Endo­ dontic treatment for preradiation patients should be determined. • Perform treatment only if urgent care is needed. • Such patients may have symptoms like mucositis, trismus, xerostomia, which will require some local treatment for relief of symptoms. 7. AIDS • Adherence to universal pre­cautions • Determine CD4 count • Medical consultation • Antibiotic prophylaxis. 8. Pregnancy: • Second trimester only seems to be safe period to provide routine dental care. • As far as possible no drug should be administered during pregnancy, especially during first trimester. If need for drug administration arises, consultation with patient’s physician is a must. • There is concern for the use of radio­ graphs in pregnant females. Use of

Case Selection and Treatment Planning



safety aids such as protective lead apron with thyroid collar is a must. • Care needs to be taken about the com­fortable position of the patient during treatment, if any kind of emergency procedure needs to be performed.

Psychological Evaluation • Patient’s psychological status is considered during treatment. • Most of the patients are found to have anxiety if they have to undergo Endodontic treatment. The anxiety reduction protocol includes reassurance to patient and explaining the entire procedure to the patient. Also, the patients need to be informed what they can expect during the treatment. • Behavioral intervention for the anxious patient reduces the anxiety and increases the level of cooperation from the patient during treatment.

Dental Evaluation Thorough clinical and radiographic evaluation of the tooth needs to be done to determine the following: (Remember the sentence: Lets Start Root Canal Procedure After Making Proper Diagnosis Previously) • Location of tooth: Most posterior tooth in the arch or tilted  posterior teeth may present access and visibility problems. Ability to isolate the tooth is an important consideration. • Strategic value of tooth. • Restorability of tooth. • Complications from previous treatment : Such as perforations, canal blockages, ledges, nonretrievable posts, etc. • Periodontal status of tooth. • Accessibility to apical foramen through the root canal. • Morphology of tooth: Root canal shape, presence of any curvatures, calcifications or resorptions, etc. which may be revealed on radiographs. But remember that radiographs do not always demonstrate canal complexities. • Proximity to anatomic structures: Proximity of root apices to anatomic structures such as mental foramen, mandibular canal and maxillary sinus should be considered. • Difficulty anticipated during treatment: Evaluating various factors that may complicate the proposed Endodontic therapy of the involved tooth. • Prognosis of the case.

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WHAT ARE THE FACTORS TO BE CONSIDERED FOR CASE SELECTION FOR ROOT CANAL TREATMENT? Factors to be Considered for Case-selection for Root Canal Treatment Systemic/General Factors These include age and health considerations. Endodontic treatment is possible for all age groups. It can be done in deciduous teeth and young permanent teeth with open apices (Pediatric Endodontics) and also in older people above 65 years of age (Geriatric Endodontics). Thus, age is not a determinant in Endodontic therapy. General health of the patient must be evaluated prior to performing root canal treatment. In case of certain medical conditions, treatment may require some modifications.

Local Factors • Consideration regarding the strategic importance of tooth: The clinician needs to determine whether the involved tooth is needed or important. Consider whether it has the opposing (antagonist) tooth or not. • Consideration regarding the status of the oral condition: The involved tooth may be associated with other dental problems such as rampant caries, periodontal lesions, orthodontic malalignment, root resorption, history of trauma, etc. Treatment of such tooth will require a combined team work of various dental specialists. • Consideration of the prognosis of Endodontic therapy: – Teeth with pre-existing apical radiolucency are found to have a lower success rate than the teeth without such lesions. Apical periodontitis is considered to be the main prognostic factor in initial treatment cases. – Clinician’s skills: Quality of instrumentation, obturation and final restoration play an important role in the ultimate outcome of Endodontic treatment. • Restorative considerations: When the tooth is badly damaged and very little amount of sound crown structure is remaining, it may not be satisfactorily restored. Surgical crown lengthening procedure (CLP) may have to be considered when crown height is compromised or there is subosseous root caries. A tooth which is Endodontically treatable but nonrestorable may represent a potential restorative complication in a large prosthesis. • Periodontal considerations: If the tooth is severely involved periodontally, it may be soon lost for

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•

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this  reason. So, in spite of probability of a favorable Endodontic prognosis, a tooth with poor periodontal support will have to be sacrificed. Esthetic considerations: As an alternative to orthodontic treatment in case of malaligned anterior teeth such as proclined teeth, intentional Endodontic treatment can be done and the teeth prepared to correct the inclination to receive full coverage esthetic crowns (Smile Designing). Surgical considerations: Cases where re-treatment is being considered, one must determine whether nonsurgical or combined means for re-treatment would be appropriate. Anatomic considerations: Extra roots and canals which are sometimes not revealed on radiographs will pose anatomic challenge before the clinician. Anatomic variations with respect to position of tooth, shape of roots and canals, presence of curvatures, calcifications, etc. should be considered during case selection. Other factors: – Ability to isolate the tooth is an important consideration.

– Accessibility of tooth: Endodontic treatment in the third molars may be difficult due to poor accessibility. Limited mouth opening, trismus can make accessibility of posterior teeth difficult or even impossible. – Retreatment cases, particularly those presenting with procedural mishaps such as ledges, perforations, etc. will pose a mechanical challenge before the clinician. – Level of anticipated difficulty in a particular case has to be determined beforehand and the need for referral to a specialist has to be considered if the case seems to be beyond the clinician’s ability. Figure 9.1 shows the mind-map to remember all the local factors to be considered for Endodontic case selection. Grossman gave the four main factors that determine the decision to do or not to do root canal treatment: (Grossman’s Endodontic Practice, 11th edn. p.126) 1. Accessibility of the apical foramen through the root canal 2. Restorability of the involved tooth

Fig. 9.1  Mind-map showing local factors for Endodontic case selection

Case Selection and Treatment Planning

3. Strategic value of the involved tooth 4. General resistance of the patient. All these have been explained previously in this chapter.

WHAT ARE THE INDICATIONS AND CONTRAINDICATIONS OF ROOT CANAL TREATMENT? Indications 1. Irreversible pulpitis: – Acute – Chronic 2. Acute apical periodontitis 3. Pulp necrosis: Necrosis of pulp may cause discoloration of tooth (Figures 9.2A and B show photograph of discolored nonvital teeth due to trauma) 4. Chronic apical periodontitis 5. Nonvital tooth with periapical cyst

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6. Chronic hyperplastic pulpitis (Pulp polyp) (Figure 9.3 shows photograph of mandibular first molar with pulp polyp) 7. Internal resorption (Pink teeth) (Figures 9.4A and B show photograph of teeth with internal resorption that have turned pink colored) 8. Pulp exposure from severe attrition of tooth (Figure 9.5 shows photograph of multiple teeth requiring root canal treatment due to pulp exposures from severe attrition) 9. Intentional root canal treatment for restorative or prosthetic procedures 10. Roots with good periodontal support, over which over denture can be constructed. 11. In case of Combined Endodontic-Periodontal lesions, in which tooth is salvageable, Endodontic treatment is done prior to Periodontal treatment.

Contraindications 1. Nonrestorable tooth, i.e. a tooth with insufficient sound tooth structure remaining (or nonrestorable root surface caries). Figure 9.6 shows photograph of badly broken down teeth due to caries that cannot be restored. Figure 9.7 shows radiograph showing insufficient sound tooth structure remaining of maxillary first premolar tooth that seems to be nonrestorable. 2. Vertical root fracture (VRF). 3. Extensive and untreatable internal or external root resorption. 4. Caries involving floor of pulp chamber. 5. Extensive periodontal disease around the tooth causing grade III mobility of tooth.

A

B Figs 9.2A and B  Discolored nonvital teeth (Courtesy of Dr Manoj Ramugade)

Fig. 9.3  Mandibular first molar with pulp polyp (Courtesy of Dr Manoj Ramugade)

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Fig. 9.6  Nonrestorable teeth (Courtesy of Dr Manoj Ramugade)

A

B Figs 9.4A and B  Pink teeth (Courtesy of Dr Manoj Ramugade)

Fig. 9.7  Radiograph showing insufficient sound tooth structure remaining-nonrestorable tooth (Courtesy of Dr Sharad Kokate)

Fig. 9.5  Multiple teeth requiring root canal treatment due to pulp exposures from severe attrition (Courtesy of Dr Manoj Ramugade)

Fig. 9.8  Radiograph showing extensive periodontal involvement in mandibular teeth

Case Selection and Treatment Planning

Figure 9.8 shows radiograph of mandibular teeth with extensive periodontal involvement. 6. Extensive destruction of periapical tissues involving more than one-third the length of the tooth. 7. Teeth with complex anatomy where proper instrumen­ tation will not be possible 8. Endodontic failure cases with complications of previous treatment such as untreatable perforations, large nonretrievable posts, canal transportations, ledges, etc. 9. Poor accessibility of tooth due to limited mouth opening which may be due to trauma, scar from surgical procedure, oral submucous fibrosis (OSMF), systemic conditions, etc. or inaccessible position of tooth in the arch. 10. Nonstrategic tooth. For example, third molars whose antagonist is missing and other all teeth are present for proper function.

HOW TO DEVELOP AN ENDODONTIC TREATMENT PLAN? After arriving at a definitive diagnosis, treatment is planned. In a general treatment plan to maintain oral health of the patient, Endodontic treatment is included in the phase II or surgical phase of treatment. But few cases may require an emergency root canal opening (ERCO) as a preliminary treatment for pain management. In case of emergency, to relieve pain: 1. For single-rooted tooth: Remove entire pulp tissue from the canal when possible 2. For multirooted tooth: a. Pulpotomy—if less time b. If some time permits, then removal of pulp tissue from largest (biggest) canal, after pulpotomy. Once the clinician has done a detailed evaluation of the case and made a definitive diagnosis and has now decided to perform Endodontic treatment, various factors need to be considered to plan, how to go about carrying out the procedure. While formulating an Endodontic treatment plan: (A) Determine the vitality of tooth: • Vital Tooth – Patient presents with severe pain in an acute vital case. Pain is due to: - Increased intrapulpal pressure - Inflammatory mediators such as prostaglandins.

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– Local anesthesia must be administered. – Simply debriding the pulp chamber, i.e. performing pulpotomy is a highly predictable method of providing pain relief in emergency cases. – If time permits, complete Endodontic treatment for vital teeth can be performed in the same visit (single visit Endodontics). If not, then clinician must stop at pulpotomy, restore the tooth with a temporary filling and schedule the next appointment for the patient. – Once the canal is entered, the clinician must remove all pulp tissue from it as it has been found that partial  instrumentation (i.e. leaving tissue remnants in the canal) may result in increased postoperative pain. • Nonvital Tooth – Can present in 3 ways: 1. In a chronic nonvital case, tooth would be absolutely painless. 2. Such a tooth, sometimes may suddenly become acutely painful due to decreased host defense mechanism and increase in virulence of bacteria. 3. Sometimes, it may be associated with a fluctuant swelling. – Nonvital tooth is a microbiologic challenge. Clinician needs to reduce the bacterial load in the root canal system by opening the tooth and debriding it. – Usually there is involvement of periradicular tissues. Clinician needs to promote decompression of periradicular tissues by instrumentation and irrigation of the canal. – If fluctuant swelling is present, incision and drainage should be performed along with instrumentation. – Single visit Endodontics is not recommended in nonvital teeth because complete eradication of infection from nonvital tooth may not be possible in a single visit due to increased microbial load. – There is role of intracanal medicament such as calcium hydroxide in these cases for antimicrobial effect in between visits. (B) Determine whether it is only an Endodontic lesion or there is periodontal involvement also: – Clinician needs to classify the case as primary Endodontic or periodontal, secondary involvement or true combined disease. Once the case is clearly classified, appropriate therapy as needed can be provided.

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Fig. 9.9  A mind-map to remember all points of Endodontic treatment plan

(C) Consider role of Endodontic surgery: – Periradicular surgery can sometimes be considered as primary treatment modality. For example, in a case of completely calcified canal. – Often periradicular surgery is considered for retreatment of an Endodontic failure case. (D) Treatment plan for retreatment case must consider the following: – Determination of: i. Cause of failure ii. Strategic value of tooth iii. Accessibility for re-entry iv. Any obvious procedural problems v. Factors affecting prognosis of tooth vi. Patient’s willingness to undergo re-treatment. – Nonsurgical retreatment sometimes may have to be combined with surgical Endodontics. – Referral to specialist may be required. Figure 9.9 shows a mind-map to remember all points of Endodontic treatment plan.

HOW TO ASSESS DIFFICULTY OF AN ENDODONTIC CASE? The American Association of Endodontists has designed the Endodontic case difficulty assessment form to assess the level of difficulty of a particular case that helps in case selection and in decision making of referral of case to an Endodontist. These forms are given on the following pages, which have been reprinted with permission from the American Association of Endodontists.

BIBLIOGRAPHY 1. ADA Council on Scientific affairs, “Office Emergencies and Emergency kits”, report in Journal of American Dental Association, 2002;133(3):364-5. 2. Cohen S, Hargreaves KM. Pathways of Pulp, 9th edn. St. Louis, Mosby, 2006.pp.80-95. 3. Grossman L, Oliet S, Del Rio C. Endodontic Practice, 11th edn. Varghese Publication, 1991.pp.126-31. 4. www.aae.org

Case Selection and Treatment Planning

PATIENT INFORMATION Name_____________________________________________________ Address___________________________________________________ City/State/Zip_____________________________________________ Phone____________________________________________________

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DISPOSITION Treat in Office: Yes ☐ No ☐ Refer Patient to: ____________________________________________________ Date: _______________________________________________

Guidelines for Using the AAE Endodontic Case Difficulty Assessment Form The AAE designed the Endodontic Case Difficulty Assessment Form for use in endodontic curricula. The Assessment Form makes case selection more efficient, more consistent and easier to document. Dentists may also choose to use the Assessment Form to help with referral decision making and record keeping. Conditions listed in this form should be considered potential risk factors that may complicate treatment and adversely affect the outcome. Levels of difficulty are sets of conditions that may not be controllable by the dentist. Risk factors can influence the ability to provide care at a consistently predictable level and impact the appropriate provision of care and quality assurance.

The Assessment Form enables a practitioner to assign a level of difficulty to a particular case.

LEVELS OF DIFFICULTY MINIMAL DIFFICULTY

Preoperative condition indicates routine complexity (uncomplicated). These types of cases would exhibit only those factors listed in the MINIMAL DIFFICULTY category. Achieving a predictable treatment outcome should be attainable by a competent practitioner with limited experience.

MODERATE DIFFICULTY

Preoperative condition is complicated, exhibiting one or more patient or treatment factors listed in the MODERATE DIFFICULTY category. Achieving a predictable treatment outcome will be challenging for a competent, experienced practitioner.

HIGH DIFFICULTY

Preoperative condition is exceptionally complicated, exhibiting several factors listed in the MODERATE DIFFICULTY category or at least one in the HIGH DIFFICULTY category. Achieving a predictable treatment outcome will be challenging for even the most experienced practitioner with an extensive history of favorable outcomes.

Review your assessment of each case to determine the level of difficulty. If the level of difficulty exceeds your experience and comfort, you might consider referral to an endodontist.

The contribution of the Canadian Academy of Endodontics and others to the development of this form is gratefully acknowledged. The AAE Endodontic Case Difficulty Assessment Form is designed to aid the practitioner in determining appropriate case disposition. The American Association of Endodontists neither expressly nor implicitly warrants any positive results associated with the use of this form. This form may be reproduced but may not be amended or altered in any way. © American Association of Endodontists, 211 E. Chicago Ave., Suite 1100, Chicago, IL 60611-2691; Phone: 800/872-3636 or 312/266-7255; Fax: 866/451-9020 or 312/266-9867; E-mail: [email protected]; Web site: www.aae.org (Reprinted with permission from the American Association of Endodontists)

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AAE Endodontic Case Difficulty Assessment Form Criteria and subcriteria

Minimal difficulty

Moderate difficulty

High difficulty

A. PATIENT CONSIDERATIONS Medical History

☐ No medical problem (ASA Class 1*)

☐ One or more medical problems (ASA Class 2*)

☐ Complex medical history/serious illness/ disability (ASA Classes 3-5*)

Anesthesia

☐ No history of anesthesia problems

☐ Vasoconstrictor intolerance

☐ Difficulty achieving anesthesia

Patient Disposition

☐ Cooperative and compliant

☐ Anxious but cooperative

☐ Uncooperative

Ability to Open Mouth

☐ No limitation

☐ Slight limitation in opening

☐ Significant limitation in opening

Gag Reflex

☐ None

☐ Gags occasionally with radiographs/treatment

☐ Extreme gag reflex which has compromised past dental care

Emergency Condition

☐ Minimum pain or swelling

☐ Moderate pain or swelling

☐ Severe pain or swelling

B. DIAGNOSTIC AND TREATMENT CONSIDERATIONS Diagnosis

☐ Signs and symptoms consistent with ☐ Extensive differential diagnosis of usual signs recognized pulpal and periapical and symptoms required conditions

☐ Confusing and complex signs and symptoms: difficult diagnosis ☐ History of chronic oral/facial pain

Radiographic Difficulties ☐ Minimal difficulty obtaining/ interpreting radiographs

☐ Moderate difficulty obtaining/interpreting radiographs obtaining/interpreting radiographs (e.g., high floor of mouth, narrow or low palatal vault, presence of tori)

☐ Extreme difficulty obtaining/interpreting radiographs (e.g., superimposed anatomical structures)

Position in the Arch

☐ Anterior/premolar ☐ Slight inclination (30°)

Tooth Isolation

☐ Routine rubber dam placement

☐ Simple pretreatment modification required for rubber dam isolation

☐ Extensive pretreatment modification required for rubber dam isolation

Crown Morphologic

☐ Normal original crown morphology

☐ ☐ ☐ ☐

Full coverage restoration Porcelain restoration Bridge abutment Moderate deviation from normal tooth/root form (e.g., taurodontism, microden) ☐ Teeth with extensive coronal destruction

☐ Restoration does not reflect original anatomy/ alignment ☐ Significant deviation from normal tooth/root form (e.g., fusion, dens in dente)

Canal and Root Morphology

☐ Slight or no curvature (25 mm) Open apex (>1.5 mm in diameter)

☐ Extensive apical resorption ☐ Internal resorption ☐ External resorption

C. ADDITIONAL CONSIDERATIONS Complicated crown fracture of immature teeth Horizontal root fracture Alveolar fracture Intrusive, extrusive or lateral luxation Avulsion

Concurrent severe periodontal disease Cracked teeth with periodontal complications Combined endodontic/periodontic lesion Root amputation prior to endodontic treatment

*American Society of Anesthesiologists (ASA) Classification System Class 1: No systemic illness. Patient healthy. Class 2: Patient with mild degree of systemic illness, but without functional restrictions, e.g. well-controlled hypertension. Class 3: Patient with severe degree of systemic illness which limits activities, but does not immobilize the patient. Class 4: Patient with severe systemic illness that immobilizes and is sometimes life threatening. Class 5: Patient will not survive more than 24 hours whether or not surgical intervention takes place. (Reprinted with permission from the American Association of Endodontists) www.asahq.org/clinical/physicalstatus.htm

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Use of Endodontic Case Difficulty Assessment Form In order to make the Case Difficulty Assessment Form a more objective exercise, it is recommended that a point score be assigned to each item within each difficulty category. This point system is offered for educational purposes only and is not recommended for clinical practice.

Those items listed in the Minimal Difficulty category are assigned a point value of 1.



Those items listed in the Moderate Difficulty category are assigned a point value of 2.



Those items listed in the High Difficulty category are assigned a point value of 5.



The following score ranges are recommended in making the decision whether to treat or refer:

• Less than 20 points: Dental student may treat—level of faculty supervision should be tailored to the student’s level of experience. • 20 – 40 points: An experienced and skilled dental student may treat with very close supervision by an endodontist, or the case referred to a graduate student or endodontist. • Above 40 points: The case should not be treated by a predoctoral dental student. The patient should be referred to a graduate student or endodontist. The assignment of an objective “point score” will hopefully assist the dental student in critically evaluating the difficulty associated with treating each patient, assist him/her in making a treatment decision that will be in the patient’s best interests, as well as enhance the student’s educational experience.

© 2005, American Association of Endodontists, 211 E. Chicago Ave., Suite 1100, Chicago, IL 60611 Phone: 800/872-3636 (North America) or 312/266-7255; Fax: 866/451-9020 (North America) or 312/266-9867 E-mail: [email protected]; Web site: www.aae.org (Reprinted with permission from the American Association of Endodontists)

CHAPTER

10

Principles of Endodontic Treatment

This chapter explains about the basic principles to be followed for Endodontic treatment which are similar to any routine surgery with few differences associated with the anatomy of the root canal system.   You must know • What are the Principles of Endodontic Treatment?

WHAT ARE THE PRINCIPLES OF ENDODONTIC TREATMENT? Grossman has given the following nine principles of Endodontic treatment as given in Figure 10.1.

Let us remember these nine principles with the help of following sentence: I T I S IMPORTANT TO DO CLEAN DENTISTRY Isolation, Trauma avoidance, Immobilization, Sterili­ zation, Irritation avoidance, Trephination, Debridement, Chemoprophylaxis, Drainage.

Principle 1: Isolation The tooth under Endodontic treatment should be isolated to maintain a safe and aseptic operative technique. Isolation of tooth can be achieved using cotton rolls and rubber dam. Use of rubber dam is mandatory during nonsurgical Endodontic therapy. Figure 10.2 shows schematic representation of teeth being isolated using rubber dam and ready for Endodontic procedure.

Rationale

Fig. 10.1  Principles of Endodontic treatment as given by Grossman

The rubber dam should be used in Endodontics for the following reasons. • Patient protection: From possible aspiration or swallowing of tooth debris, restorative materials, Endodontic instruments (files), medicaments, irrigating solutions, etc. • Dry, clean operating field: Prevents contamination of root canal system from saliva, blood and other tissue fluids. • Retraction: Adjacent soft tissues (tongue, lips, cheek) are retracted and protected.

Principles of Endodontic Treatment

Fig. 10.2  Schematic representation of teeth being isolated and ready for Endodontic procedure

• Visibility: Rubber dam provides a dry field and reduces mirror fogging, thus improving visibility. • Increased efficiency: Better visibility increases efficiency of operator. Also, since the rubber dam minimizes patient conversation during treatment and frequent rinsing by the patient, there is increased efficiency due to bacteria free field. • Standard of care: Use of rubber dam for Endodontic treatment is considered as the standard of care. Routine placement of rubber dam eliminates the risk of accidental swallowing or aspiration of instruments and medicaments, etc. thus the clinician is protected from litigation. Figures 10.10 and 10.12 show photographs of Rubber dam isolation of tooth undergoing Endodontic treatment. – In certain instances such as severe tipping of teeth or orientation difficulties due to restoration, the coronal access to root canals needs to be made prior to rubber dam placement.

Components of Rubber Dam System (Fig. 10.3)

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Fig. 10.3  Rubber dam kit containing rubber dam sheets, rubber dam frame, rubber damp clamp or retainers, rubber dam punch and rubber dam forceps (Courtesy of Dentsply)

Rubber Dam Sheet/Material • Available in variety of thicknesses: – Thin – Medium – Heavy – Extra heavy – Special heavy Medium weight thickness is recommended for Endodontic purposes as it gets tightly adapted to cervical area of tooth and does not tear easily. It retracts soft tissues better than the thin type and is easier to place than the heavier types. Thin material needs to be used on mandibular anterior teeth and partially erupted posterior teeth. Figure 10.4 shows photograph of rubber dam sheet. • 2 sizes: 5 × 5 inches (127 × 127 mm) 6 × 6 inches (152 × 152 mm) Figure 10.5 shows photograph of commercially available packets containing 6 × 6 inches rubber dam sheets. • Available in variety of colors: Light yellow, blue, green, gray • 2 sides of sheets: One side is dull, other side is shiny Dull side of rubber dam should be towards the operator. Two types of rubber dam material: 1. Latex rubber dam 2. Nonlatex: Nitrile or nonlatex rubber dam (for patients with allergy to latex).

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Fig. 10.4  Rubber dam sheet (Courtesy of Mr Amar, Dr Dabholkar’s Clinic)

Fig. 10.6  Rubber dam frame (Courtesy of Mr Amar, Dr Dabholkar’s Clinic)

Fig. 10.5  Commercially available packed rubber dam sheets (Courtesy of Mr Amar, Dr Dabholkar’s Clinic)

Fig. 10.7  Rubber dam clamps (Courtesy of Dr Shivani Bhatt)

Rubber Dam Frame

Rubber Dam Clamp or Retainer

• To retract and stabilize the rubber dam • Two materials of frames – Metal (Nygaard Ostby frame) – Plastic (Young’s frame) • For Endodontic purposes, plastic frames are recommended as they are radiolucent and do not cause obstruction of important areas on radiographs. Figure 10.6 shows photograph of plastic rubber dam frame. • U-shaped Young’s rubber dam frame made of plastic is commonly used. • Foldable plastic frame is also available which need not be disengaged while taking radiograph.

• To anchor the rubber dam to the tooth requiring Endodontic treatment • It also helps in soft tissue retraction • Two types:

– For Endodontic purpose, wings allow rapid and efficient placement of dam.

Principles of Endodontic Treatment



Figure 10.7 shows photograph of the rubber dam clamps. – Wings cause buccal-lingual deflection of dam from isolated tooth, allowing increased access. – Disadvantage: Wings may sometimes interfere in radiographic interpretation. • Parts of clamp: A bow and two jaws. • Available in 2 sizes: Small and large.

Rubber Dam Punch • To punch sharp, clean holes on rubber dam sheet according to the tooth to be isolated. Figure 10.8 shows photograph of rubber dam punch. • If the punch is not centered correctly, a ‘nick’ or jagged cut margin is produced resulting in poor seal.

Rubber Dam Forceps • To hold and carry the retainer during placement and removal. Figure 10.9 shows photograph of rubber dam forcep. • Ash-style or ivory-style forceps is used • Ash-style forceps beaks provides a fulcrum point for posterior or anterior rotation of clamp • Ivory-style forceps provides projections from engaging beaks that allow the clinician to exert gingivally directed force necessary to direct the clamp beyond the bulk of contour and into proximal undercuts.

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– To shed the rubber dam off the wings of the clamp after the clamp is positioned. • Dental floss. – To check contacts prior to rubber dam application. – To pass the rubber dam material through the contacts after placement. • Wedgets stabilizing cord: Small strips of cord wedged into interproximal space, help to stabilize the interproximal area of rubber dam. • Orabase, rubber base adhesive, cavit, periodontal pack: To control seepage of fluids at the interface of the tooth and the rubber dam material. Recently, disposable, single use, preframed rubber dams have been introduced. For example, Instadam and HandiDam for quick application of rubber dam without the use of conventional frame.

Methods of Rubber Dam Placement

• Plastic or cement instrument: – To ‘tuck’ the edges of rubber dam into gingival sulcus to achieve a fluid tight seal.

Patient is asked to rinse for 30 seconds with an antibacterial agent such as 0.12% chlorhexidine gluconate, to reduce the number of microorganisms in mouth prior to rubber dam placement. • Single motion technique: Most efficient dam application technique for Endodontics. It is named so, as the dam, clamp and the frame are taken to the tooth to be isolated in a single motion. – Position the bow of the selected clamp through the hole made in rubber dam sheet. – Place the rubber dam over the wings of the clamp. – The forceps stretch the clamp to maintain the position of the clamp in the dam.

Fig. 10.8  Rubber dam punch (Courtesy of Mr Amar, Dr Dabholkar’s Clinic)

Fig. 10.9  Rubber dam forcep (Courtesy of Mr Amar, Dr Dabholkar’s Clinic)

Adjuncts to Rubber Dam Placement

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– Then the rubber dam is attached to the plastic frame, thus allowing for the placement of the dam, clamp and frame in one motion. – Once the clamp is secured on the tooth, a plastic instrument is used to tease the dam under the wings of the clamp. – Use dental floss to pass the dam through contacts. • Double motion technique. – Punch appropriate size hole on the dam material. – Then the rubber dam is loosely attached to the four corners of the frame. – The selected clamp is placed over the bulk of contour of the tooth to be isolated. – The rubber dam is stretched over the clamp. – Then it is stretched onto all prongs of the frame. – Use dental floss to pass the dam through the contacts. Figure 10.11 shows diagrammatic representation of rubber dam placement. • Split dam technique: To isolate anterior teeth without using rubber dam clamp. It can also be used for tooth with insufficient structure. Figure 10.10 shows photograph showing rubber dam in place for Endodontic treatment in mandibular first molar and Figure 10.12 shows access opening of maxillary central incisor with rubber dam in place.

c. The stretched interproximal dam is cut with scissors and dam is removed. d. Inspect and ensure that no interproximal dam has been left in between teeth.

Problems Encountered in Rubber Dam Placement • Leakage – Due to error in placement, seepage can occur. – In patients with excessive salivation, saliva may seep even through well-placed rubber dam. Solution – Meticulous placement of rubber dam. – Premedication with anticholinergic drug to reduce saliva.

Rubber Dam Removal. i. In case of rubber dam applied to isolate single tooth, remove the clamp with the forceps and remove the rubber dam. ii. In case of multiple teeth applications a. Remove the clamp. b. Place finger under the dam in the vestibule and stretch the dam to the facial, away from the teeth.

Fig. 10.11  An ivory no. 3 clamp has been trial-fitted to the mandibular first molar. After trying, the clamp is removed and placed on the rubber dam (Single motion technique) or the rubber dam is stretched over the clamp (Double motion technique)

Fig. 10.10  Rubber dam in place for Endodontic treatment in mandibular first molar (Courtesy of Dr Manoj Ramugade)

Fig. 10.12  Access opening in maxillary central incisor with rubber dam in place (Courtesy of Dr Manoj Ramugade)

Principles of Endodontic Treatment

• Insufficient tooth structure: There is problem during placement of clamp. Solution – Use clamps with prongs inclined apically. – Consider restorative procedures to build-up the tooth so that the retainer can be placed properly. – Canal projection technique: Allows pre­ Endodontic build-up of broken down coronal and radicular structure while preserving individualized access to canal. Pre-Endodontic build-up: It may be necessary in some cases to supply a missing wall with amalgam or composite or an orthodontic band may be cemented over the remaining natural crown before Endodontic treatment is begun to prevent the rubberdam clamp from slipping off the tooth and to facilitate proper placement of retainer. • Partially erupted, broken tooth or tooth prepared for crown: Cause inadequate clamp placement. Solution: Customize the rubber dam retainer by modifying the jaws to adapt to a particular tooth. • Tooth with extreme mobility or multiple adjacent teeth requiring treatment: Clamp the posterior tooth normally, whereas a second clamp is reversed on the most anterior tooth. Or Clamp the posterior tooth normally, whereas anterior portion of dam is retained without a clamp. Situations where use of rubber dam is contraindicated: • Asthamatic patients • Patients with allergy to latex, nonlatex material will have to be used. • Mouthbreathers

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• Grossman’s statement: “It is not so much what you put into a root canal, but what you take out that counts.” Although for successful Endodontic treatment, both are important.

Principle 4: Drainage In case of gross infection and swelling, drainage is established through the root canal or incision or both. Drainage through the root canal is preferable as it allows pus, necrotic tissue, toxic products and gas to escape. But in case if access is difficult, or tooth is very tender and access cavity cannot be prepared and a soft fluctuant swelling present, then incision and drainage is treatment of choice. Drainage through the incision is made from the most dependent part of the swelling near the root apex. In case of a hard swelling, it is converted into soft, fluctuant swelling by warm rinses and then the incision is made. In case of swelling, patient should be instructed not to apply heat to outside of face, as it can cause sinus tract (fistula) leaving a scar. In case of a large swelling, after the incision is made, a drain is inserted to keep the wound open.

Principle 5: Chemoprophylaxis Patients with history of rheumatic fever or congenital heart disease require prophylactic antibiotics to prevent bacterial Endocarditis. Two gram of phenoxymethyl penicillin 1 hour before treatment and then 1 g six hours postoperatively. In case of allergy to penicillin, erythromycin is given. Dose is 1 g 1 hour before treatment and 500 mg 6 hours postoperatively.

Principle 6: Immobilization Principle 2: Sterilization This principle is discussed in detail in Chapter 12.

Principle 3: Debridement • The infected root canal must be cleaned of debris by thorough biomechanical preparation (cleaning and shaping) and chemical means by use of root canal irrigants and disinfectants. • Combination of instrumentation and irrigation help to remove all necrotic material and debris from the root canal resulting in complete debridement and cleansing of root canal. • Presence of dead tissue in the canal prevents disinfection and repair.

The affected tooth can be immobilized by relieving occlusal stress or contact with the opposing tooth. Slightly relieving occlusion in an Endodontic case, lessens the possibility of traumatizing the periodontal ligament. Another philosophy is only to disocclude in lateral excursive movement. Figures 10.13 and 10.14 show relieved occlusal cusps of mandibular molar during the first appointment of Endodontic treatment.

Principle 7: Avoidance of Trauma • Gentle handling of soft tissues • Prevent overinstrumentation

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Fig. 10.13  Reduction of occlusal contacts to relieve the tooth of occlusion during the first appointment of Endodontic treatment (Courtesy of Dr Manoj Ramugade)

Fig. 10.14  Access preparation and relieved occlusal contact of mandibular molar during first appointment of Endodontic treatment, to reduce the possibility of pain by traumatizing PDL (Courtesy of Dr Manoj Ramugade)

Fig. 10.15  A mind-map to remember the principles of Endodontic treatment

Principles of Endodontic Treatment

• Determine accurate working length and follow it during instrumentation to confine all the instruments within the root canal to minimize trauma to periapical tissues.

Principle 8: Trephination • Trephination means creating a surgical passage in the region of root apex using a bur or a special drill to provide a channel for the escape of pus and blood. This is done to relieve the pressure of accumulated fluid or gas in the jaw bone. • Indications: – Acute alveolar abscess – Teeth with large areas of rarefaction – Overfilled canal with lot of pain and discomfort – Postoperative pain following obturation. • Not generally recommended as it itself causes surgical trauma.

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Principle 9: Irritation by Chemicals Avoidance Irrigating solutions such as sodium hypochlorite or hydrogen peroxide, if forced through the apical foramen can cause considerable pain and edema. All such irritating drugs should be confined to the root canal itself and should not be forced through the apical foramen. Figure 10.15 shows mind-map to remember all points of the principles of Endodontic treatment.

BIBLIOGRAPHY 1. Cohen S, Hargreaves KM. Pathways of Pulp, 9th edn. St. Louis: Mosby, 2006.pp.120-7, 2. Grossman L, Oliet S, Del Rio C. Endodontic Practice, 11th edn. Varghese Publication, 1991.pp.132-44. 3. Ingle J, Bakland L, Baumgartner J. Ingle’s Endodontics, 6th edn. BC Decker Inc, Hamilton, 2008.pp.791-9,

CHAPTER

11

Endodontic Armamentarium: Instruments, Materials and Devices

This chapter classifies the Endodontic Armamentarium according to their use in various Endodontic procedures. Some of them have only been listed, their detailed description is given in the respective chapters along with the procedures and techniques in which they are used.   You must know • What Changes have Occurred in the Endodontic Armamentarium in the Practice of Modern Endodontics? • What are the Devices used for Enhanced Vision, lllumination and Magnification? • What are the Instruments, Materials and Devices used as Diagnostic Aids in Endodontics? • What is the Armamentarium for Administration of Local Anesthesia? • What are the Materials used for Isolation of Endodontic Field? • What is the Armamentarium Needed for Access Cavity Preparation? • What are the Instruments and Devices for Determination of Working Length? • What are the Materials used for Disinfection of Root Canal? • What are the Instruments and Devices for Root Canal Preparation (Endodontic Instruments)? • What are the Instruments used for Obturation of Root Canal System? • What are the Instruments and Devices for Removal of Root Canal Obstructions and Fillings? • What are the Materials used as Temporary Restorations? • What are the Materials used for Post-Endodontic Restoration? • What is the Armamentarium for Periradicular Surgery? • What is the Role of Laser Device in Endodontics?

WHAT CHANGES HAVE OCCURRED IN THE ENDODONTIC ARMAMENTARIUM IN THE PRACTICE OF MODERN ENDODONTICS? In last 2–3 decades, following changes have occurred in the Endodontic armamentarium: • Enhanced vision with magnification devices such as surgical operating microscope/dental operating microscope. • Improvements in diagnostic aids: For example, – Enhanced imaging with digital radiography (RVG) – Laser Doppler flowmeter and other newer devices to precisely detect pulp vitality – Advanced 3D imaging—Cone beam computed tomography (CBCT) scans.

• Electronic apex locators to precisely determine the working length and the apical termination position (apical constriction) of root canal preparation and filling. • Improved instruments for effective coronal and radicular access cavity preparation. • Nickel-titanium Endodontic instruments for refined cleaning and shaping of canals. • Thermoplasticized and newer obturation systems for denser and three-dimensional obturation with guttapercha. • Improved and simplified post systems and core build-up materials for badly broken down teeth. • Microsurgical instruments for periradicular surgery. • Retreatment devices for removal of old obturations and obstructions.

Endodontic Armamentarium: Instruments, Materials and Devices

• Ultrasonic devices for enhanced irrigation and many other irrigation devices and methods. • Introduction of lasers in Endodontics. Newer armamentarium have made Endodontic treatment predictable, quicker and simpler too!

WHAT ARE THE DEVICES USED FOR ENHANCED VISION, ILLUMINATION AND MAGNIFICATION? Earlier, the root canal system could be viewed only on the radiographs and that also gave a two-dimensional image of the three-dimensional biological system. But with the advent of optical magnification instruments such as loupes, microscope, endoscope and orascope, the root canal system can actually be viewed in a magnified form, thereby allowing the clinician to perform the Endodontic procedures with great precision and ease.

Dental Loupes • Also called as surgical telescopes. • Dental loupes are currently the most common magnification aid used in dentistry. • Dental loupes consist of convergent lenses attached to the regular glasses of the spectacles. Figure 11.1 shows photograph of Loupes. • Single lens loupes have fixed focal length and working distance. • Loupes used in dentistry generally consist of multilens optic system called as Galilean optical system that provides better magnification and improved working distance.

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• Properties of telescopic loupes: – Magnification : L oupes are available with magnification of 2X, 2.5X, 4X, 6X, etc. 2.5X is considered to be ideal magnification with telescopic loupes, as higher magnification causes problems such as change in depth of field with the change in operator’s position, and problems related to working distance. Also, more illumination is required with increase in magnification in loupes. – Working distance: Distance from dentist’s eye to the field of treatment is the working distance. 2.5X magnification allows comfortable working distance thus improved posture of the operator while working. – Depth of field: It is the distance between the nearest and the farthest objects appearing in a sharp focus. Dental loupes provide good depth of field. – Field of view: It is the total area visible through optical magnification. Dental loupes provides an acceptable field of view required to perform regular procedures. – Illumination: Some of the loupes are manufactured with the attached light sources to improve illumination. • Advantages: – Improved vision due to magnification – Improves body posture during working preventing the possible neck and back strain – Good optical properties – Acceptable weight • Disadvantages: – Does not satisfy the magnification need for Endodontic treatment which may be from somewhere around 3X to 30X. If more than 2.5X magnification is used with loupes, problems occur related to depth of field and working distance – Weight on the face and head of the operator while working which may be quite uncomfortable. – Optical performance not acceptable for Endodontic purposes. – Some clinicians may take time to get used to it.

Dental Operating Microscope/ Surgical Operating Microscope

Fig. 11.1  Photograph showing loupes (Courtesy of Dr CR Suvarna)

• The use and benefits of an operating microscope for conventional Endodontics was first reported by Baumann. • Dental operating microscope (DOM) or surgical operating microscope (SOM) also uses the Galilean lens system.

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• It is an invaluable optical magnification instrument. • With the advent of DOM, performing Endodontic therapy is no longer a blind procedure that was earlier based on tactile sensation and presumptions. • Components of DOM and its uses: The components of DOM include the following: – Eye piece – Binocular field glasses – Magnification changer – Objective lens – Fiberoptic light source Figure 11.2 shows schematic view of dental operating microscope and Figure 11.3 shows the photograph of the head portion of the dental operating microscope. - In DOM, the eyepiece connected to the binocular field glasses allows adequate focal length, the magnification changer adds to the flexibility of DOM and the objective lens increases the magnification. - The magnification of DOM is determined by : a. The magnification power of the eyepiece: The eyepiece has -5 to +5 diopter settings which are used to adjust for accommodation (ability to focus the lens of eyes). b. The focal length of the binoculars: The distance between the binocular tubes is adjusted to set the interpupillary distance. With increased focal length, the magnification is more but the field of view becomes less. c. The magnification changer factor: Magnifica­ tion changers are located within the head

•

•

•

•

Fig. 11.2  Dental operating microscope

of microscope and are available as 3- to 5-step manual changers or power zoom changers. Manual step changers contain lenses mounted on a turret. Power zoom changers is series that move back and forth on a focusing ring giving wide range of magnification factors. d. The focal length of the objective lens: Objective lenses with focal length ranging from 100 to 400 mm are available. The focal length of objective lens determines the operating distance between the objective lens and the surgical field. - DOM satisfies the magnification need of Endodontic treatment. DOM can provide magni­ fication ranging from  3X to 27X. The required magnification can be adjusted. Illumination – The light source for DOM is 100 watt xenon (white)/ halogen bulb (yellow) – The intensity of light is controlled by rheostat, then light reflected to a series of prisms (through condensing lens) and then to surgical field (through objective lens) – The light reaches the surgical field and is reflected back to the eyes as two separate beams of light (through the objective lens through magnification changer lenses through binoculars) causing a stereoscopic effect allowing clinician to see depth of field. Documentation using DOM – Good quality slides and videos can be obtained if the quality of the magnification and illumination systems within the microscope is good. – Beam splitter provides illumination for photographic and video documentation and is attached to the camera through an adaptor. Accessories: Include – Auxillary monocular or binoculars that can be added and used by dental assistant. – LCD screen, which receives its signal from video camera, etc. Mounting of DOM: – The head portion of microscope should be firmly attached to a rigid surface in order to reduce its oscillating movement, – The head portion of DOM is supported by a counterbalanced arm which in turn is attached to a floor, wall or ceiling for its free movement and for easy access to oral cavity.

Endodontic Armamentarium: Instruments, Materials and Devices

• Instruments used for Micro-Endodontics: – While using DOM for viewing Endodontic treatment field, a standard dental mirror or micromirror is used to overcome the angulation difficulties of certain tooth positions in the mouth. Mirror placed slightly away from the tooth at an angle of 45 degrees to the microscope for better view. – Microinstruments for locating canals – Endodontic files called micro-openers – Other microinstruments. • Advantages: – Enhanced vision of treatment field due to enhanced illumination and magnification. – Dentin can be removed with great precision. – Increased ability to locate and negotiate canals. – DOM is a valuable aid for removing separated instruments, for diagnosis of microfractures and for repairing root perforations. – DOM is a very useful tool for case documentation. – In Surgical Endodontic treatment, DOM is very effective as it causes enhanced view of surgical treatment field and need to take fewer radiographs. – With DOM, the Endodontic management of failed cases has become easier and more predictable. • Disadvantages: – Cost – Difficulties encountered while using it related to convenience, position, angulation, etc. till the clinician gets trained and experienced. – Increased treatment time. Other advanced magnification devices: Endoscope and orascope (Fiberoptic Endoscope)

Fig. 11.3  Photograph of head portion of dental operating microscope (Courtesy of Seiler)

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WHAT ARE THE INSTRUMENTS, MATERIALS AND DEVICES USED AS DIAGNOSTIC AIDS IN ENDODONTICS? Endodontic Armamentarium required for diagnosis and various diagnostic procedures include: • Instruments for clinical examination: – Mouth mirror – Standard dental explorer – Periodontal probe – DG-16 Endodontic explorer. Figure 11.4 shows schematic representation of DG-16 Endodontic explorer. • Radiography: Discussed in detail in Chapter 7 Diagnosis and Diagnostic Aids in Endodontics. • Instruments and materials for diagnostic tests: – Materials used for thermal tests: (Thermometric evaluation) Agents for heat test: - Warm water bath - Heated ball burnisher - Heated gutta-percha stick - Rotating burlew rubber wheel - System B Agents for cold test: - Sticks of ice - Frozen CO2 or dry  ice (–78oC) - Endo ice (1,1,1,2-Tetrafluoroethane): - Ethyl chloride - Cold water bath. Thermal tests are explained in detail in Chapter 7 Diagnosis and Diagnostic Aids in Endodontics. • Device for electric pulp test: Electrometric/Electric pulp tester Electric pulp tester (EPT): – It is used to evaluate the responding nerve endings. When an electric current is passed through the tooth, patient feels the sensation as a result of direct nerve stimulation. – Various types of EPT are commercially available. Some newer units have electric pulp testing and Electronic apex locator combined in one unit. – Electric pulp testing is based on Ohm’s law: E = R × I (where E—Electromotive force, R—Resistance, I—Current flowing through resistance.) Enamel and dentin constitute high resistance in electric circuit

Fig. 11.4  Schematic representation of DG-16 Endodontic explorer

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through the tooth. The pulp testers operate at high potential difference but a very low current (mA). – Earlier, electric pulp testing devices were not wellcalibrated and had such a design that sometimes applied higher current directly to the tooth causing great discomfort. – Newer electric pulp tester (EPT) devices use battery or AC power in which the speed of delivery of current can be adjusted. Figure 11.5 shows schematic representation of electric pulp tester. The electric pulp test has been described in Chapter 7: Diagnosis and Diagnostic Aids in Endodontics. • Device for testing pulp vitality: Laser Doppler flowmeter and pulse oximeter assess pulpal blood flow to determine the pulp vitality. (Explained in Chapter 7: Diagnosis and Diagnostic Aids in Endodontics) • Devices used for bite test: – Cotton rolls – Wooden end of cotton tip applicator – Rubber polishing wheel – Tooth slooth: Tooth slooth is specifically designed for performing bite test. Figure 11.6 shows photograph of tooth slooth. It has the design that allows the biting force to be applied  selectively to one cusp at a time so that the specific areas can be determined for the diagnosis of incomplete crown fracture. Bite test is described in Chapter 7: Diagnosis and Diagnostic Aids in Endodontics. • Stains used for caries detection and for diagnosis of cracks or fracture: – Acid red in 1% propylene glycol – Methylene blue dye – India ink

Fig. 11.5  Electric pulp tester

Figure 11.7 shows photograph of commercially available caries detector dye. • Devices for transillumination test: Fiberoptic light is used as light source, which can be specifically designed for transillumination test. Figures 11.8A and B shows photograph of fiberoptic light source for transillumination test. Handpiece with fiberoptic activated or other bright point light source can also be used for transillumination. Transillumination test has been explained in Chapter 7: Diagnosis and Diagnostic Aids in Endodontics.

Fig. 11.7  Commercially available caries detector dye (Courtesy of Mr Amar, Dr Dabholkar’s clinic)

A

B Fig. 11.6  Tooth slooth (Courtesy of Dr CR Suvarna)

Figs 11.8A and B  Fiberoptic light source for transillumination test (Courtesy of Dr CR Suvarna)

Endodontic Armamentarium: Instruments, Materials and Devices

WHAT IS THE ARMAMENTARIUM FOR ADMINISTRATION OF LOCAL ANESTHESIA? • Topical local anesthetic agent • Lignocaine hydrochloride 2% with and without Adrenaline • Disposable syringes and needles • Cartridges • Special pressure syringe for intrapulpal anesthesia. (These have been discussed in Chapter 17: Drugs or Medicaments used in Endodontic Treatment)

WHAT ARE THE MATERIALS USED FOR ISOLATION OF ENDODONTIC FIELD? Use of rubber dam is considered to be mandatory for nonsurgical Endodontic therapy. Rubber dam armamentarium has been discussed in detail in Chapter 10 ‘Principles of Endodontic Treatment’.

WHAT IS THE ARMAMENTARIUM NEEDED FOR ACCESS CAVITY PREPARATION OF ROOT CANAL? Magnification and Illumination • Use of magnification and an appropriate light source is needed for adequate access cavity preparation. • The preferred means of magnification and illumination is dental operating microscope (DOM). If not, then surgical loupes with an auxiliary light source should be used at least.

A

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Handpieces • High speed handpiece: For initial penetration. • Slow speed handpiece: For deeper penetration and in case of calcified and receded pulp chambers. • Low-speed contra-angle handpiece.

Burs (Figs 11.9A and B) • For removal of caries, initial penetration and deroofing the pulp chamber: – Round carbide burs (Medium sizes such as #2, #4). – In case if the teeth requiring access preparations have restorations such as porcelain fused to metal crown, then Round diamond burs need to be used. – In case if the tooth has receded pulp chamber and calcified orifices, Extended shank round burs will have to be used that move the head of handpiece away from tooth, thus improving visibility. For example, LN Bur (Dentsply) or Ultrasonics can be used. – Tapered fissure burs with rounded cutting end: Advantage is that same can be used for axial wall extension of access cavity preparation. But should be carefully used, especially by inexperienced clinicians as their cutting ends can gouge the pulp floor and axial walls. – Transmetal burs (for penetration through metal) • For extension of axial walls: – Safe-ended diamond and tungsten carbide burs. These burs have the tip or end which is noncutting and sides are cutting. For example, Endo access bur, Endo Z bur, safe nonend cutting bur.

B

Figs 11.9A and B  Access preparation bur kit showing round bur, transmetal bur, long shank round burs, safe-ended bur and X-gates (Courtesy of Dentsply)

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A

B Figs 11.10A and B  Safe-ended carbide bur: (A) Endo access bur; (B) Endo Z bur (Courtesy of Dentsply)

Fig. 11.11  Gates Glidden 1 to 6

Figures 11.10A and B shows photograph of safeended carbide bur. These burs are used for final refinement extending from enamel to pulpal floor orienting the bur along the axial walls without causing gouging. So, they are safer choice for axial wall extensions. • For occlusal reduction: Fissure carbide and diamond burs also can be used to reduce or level off the cusp tips and incisal edges for two reasons: – Disocclusion of tooth in case of inflammation. – Flat cusp tips and incisal edges can be used as reproducible reference points during working length determination. • For enlarging the orifices and preflaring of coronal portion of root canal: Root canal orifices have to be blended into the axial walls in order to gain straight-line access (SLA) so that the subsequent instruments used for cleaning and shaping can enter the root canal easily and effortlessly. This can be done using Gates Glidden drills.

is the narrowest diameter lying adjacent to the handpiece. If the drill binds during use and the instrument separates, the separation occurs at the neck and the separated part can be removed from the canal easily.   Flame-shaped head cuts laterally and it has a safe tip to guard against perforations. – The GG drills are available in various lengths such as 28 mm, 32 mm, etc. – The GG drills are available in a set of 6 instruments with a diameter ranging from 0.5 mm to 1.5 mm. The specific drill size can be identified by the number of rings on the shank. Figure 11.11 shows photograph of Gates Glidden drills 1–6. GG 1: 0.5 mm diameter (ISO size # 50) with one ring on shank GG 2: 0.7 mm diameter (ISO size # 70) with two rings on shank GG 3: 0.9 mm diameter (ISO size # 90) with three rings on shank GG 4: 1.1 mm diameter (ISO size # 110) with four rings on shank GG 5: 1.3 mm diameter (ISO size # 130) with five rings on shank GG 6: 1.5 mm diameter (ISO size # 150) with six rings on shank. An instrument called X gates (GG X) drill has been manufactured which has features of GG1 to GG4. It has no ring on the shank. It has better cutting efficiency.



Gates Glidden Drills These are engine driven reamers used in Endodontics. • Instrument design: – Gates Glidden (GG) drill has - A long, thin shaft - A flame-shaped head with a safe tip.   Shaft is designed in such a way that the weakest part of the shaft is at the neck, which

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progressing shorter than the preceding one with larger size drills in sequence. Fig. 11.12  X Gates (GGX)

Figure 11.12 shows diagrammatic representation of X-gates (GGX). • USES: GG drills are used for: – Pre-enlargement of coronal areas of root canal. – To remove dentin overhangs such as lingual shoulder in anterior teeth and the cervical dentin bulge in posterior teeth during access preparation in order to achieve straight line access (SLA) to the canals. – To clean and shape the cervical 1/3rd of the root canals using the step-back and step-down (crowndown) techniques. – GG drills open and flare the root canal orifices that facilitates better cleaning by allowing more amount of irrigants to penetrate into the root canal system and better shaping procedures by establishing smooth glide path from the access cavity into the root canal system.

Cutting Action The GG drills are side-cutting instruments that cut dentin during an outstroke movement as they are withdrawn from the canal. The optimum speed at which the GG drills can be used safely is about 800 rpm (750–1500 rpm). While using GG drills, they should be directed away from the external root concavities in anterior teeth and the furcation area in posterior teeth to prevent mishaps such as perforations. In posterior teeth, using GG drill in the direction of the name of the canal directs it away from the furcation.

Advantages • Safe to use • Inexpensive • No fear of separation in the canal as in case if it does separate, it occurs at the neck so that the separated part can be easily removed from the canal • Useful for initial opening of root canal orifices and also for deeper penetration in both straight and curved canals • Causes pre-enlargement of coronal part of canal making the subsequent cleaning and shaping procedures easier.

Disadvantages Improper use can cause: • Strip perforations of canals: – Such as using it at a high speed – Applying excessive pressure while using – Inserting it in incorrect direction. • Fracture of short cutting heads: Due to high torsional loads or due to cyclic fatigue when GG drills are used in the areas of curvature of the canals, the short cutting heads may fracture. • Coke bottle preparation: Overzealous use of GG drills causes  the so-called “coke-bottle” shape of canal, as shown in Figure 11.13.

Manner of Use The GG drills are used with air motors or preferably with electric gear reduction handpieces. They should be inserted in the correct direction and used passively without any pressure. They should be used only in straight portion of canal. Their use should follow the sequence of their sizes. • In step-down technique, starting with larger size drill that can be introduced into the orifice and progressing deeper into the coronal 1/3rd of root canal with smaller size drills. • In step-back technique, starting with smaller size drill into the coronal 1/3rd of root canal and withdrawn and

Fig. 11.13  Overzealous use of Gates Glidden causing coke bottle effect

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Fig. 11.14  A mind-map to remember Gates Glidden drills



A mind-map to remember all points of Gates Glidden drills is given in Figure 11.14.

Hand Instruments for Access Preparation • • • •

Mouth mirror Probe Explorer DG-16 Endodontic explorer: It is used for location of root canal orifices and to determine the angulation of the canals. The two ends of Endodontic explorer are sharp and angled in two different directions from the long axis of instrument.

• Endodontic spoon excavator or Endodontic spoon is slightly different from regular dental spoons in that they have a much longer offset from the long axis of the instrument for better reach inside the constricted pulp chambers. This is used to: – Scoop out carious dentin – To excise coronal pulp tissue. Figures 11.15A and B shows diagrammatic representation of DG-16 Endodontic explorer and Endodontic spoon excavator respectively. Endodontic spoon excavators are designed in such a way that they are offset from the long axis of the instrument.

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A B Figs 11.15A to B  Diagrammatic representation of DG-16 Endodontic explorer (A) and Endodontic spoon excavator (B)

This design facilitates access to the constricted pulp chambers so that the entire pulp tissue can be removed.

Ultrasonic Unit and Various Ultrasonic Tips During access cavity preparation, ultrasonic tips can be useful for exploring the root canal orifices by troughing and deepening the developmental grooves to remove the tissue with minimal collateral tooth structure removal. Figure 11.16 shows Endodontic ultrasonic tips. Ultrasonics for Endodontic use has been described in detail, later in this chapter.

WHAT ARE THE INSTRUMENTS AND DEVICES FOR DETERMINATION OF WORKING LENGTH? • Millimeter ruler or Endo block for measurement of instrument length • Radiographs • Smaller size, i.e. #8, #10, #15 number K-files with rubber stops • Electronic apex locators • Paper points. Currently, it is believed that the use of radiographs in combination with the apex locators can accurately determine the working length. Details of working length determination using the above are given in Chapter 14 Cleaning and Shaping of Root Canal System Including Working Length Determination.

Electronic Apex Locator Electronic apex locator is an electrical device which helps to estimate the working length. It indicates the position of apical constriction by means of some “sound”, or “movement of a dial on the display screen”.

Fig. 11.16  Start X ultrasonic tips 1—Access cavity walls, 2—MB2 canal scouting, 3—calcified canal scouting and fiber postremoval, 4—Metal postremoval, 5—finishing pulp chamber floor. (Courtesy of Dentsply)

Generations of Apex Locator • First generation apex locators: Also called resistance apex locator and are based on direct current. – Principle: Based on the principle that the resistance offered by periodontal ligament and oral mucous membrane is the same. – With the file advancing in the canal, when the conductive periodontal ligament is reached, the resistance decreases until the circuit is complete. – The first generation apex locators are no longer used. • Second generation apex locators: – Principle: Based on impedance of single-frequency, that measure opposition to the flow of alternating current. The property of impedance includes both resistance and capacitance. – These apex locators gave more information than the first generation apex locators. The first and second generation apex locators were found to be sensitive to the contents of the canal including the irrigating solutions used during treatment. So they require the canals to be dry to give accurate readings. • Third generation apex locators: – Principle: Based on impedance of multiple frequencies. – There is difference in impedance in different parts of the root canal, being least in the coronal part of the canal and greatest at the cementodentinal junction.

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– It was found that electrolytes did not have significant effect on the accuracy of the unit. – Commercially available third generation apex locators include: Root ZX which emits the current at the frequency of 8 and 0.4 KHz and the Endex device which emits the current at the frequency of 1 and 5 KHz. • Fourth generation apex locators: – These apex locators are the latest ones that use multiple frequencies and they overcome the disadvantages of the previous generation apex locators. – Principle: It measures the individual components of impedance, i.e. resistance and capacitance independently and compares the information to a database to determine the correct working length. – Less chances of error as different combinations of the properties provide the same reading of impedance. – Since multiple frequencies are used, the electrolytes or canal contents do not have any effect on the accuracy of the unit. – Commercially available fourth generation apex locators include APA apex finder and Elements diagnostic unit. The third and fourth generation apex locators are based on the fact that: There is difference in impedance between the high and low frequencies at different portions of root canal. • Coronal portion of the canal shows the least difference between frequencies. • Deeper portions of the canal show more difference between frequencies. • Cementodentinal junction of the canal shows the greatest difference between frequencies.

Components of an Electronic Apex Locator • Lip clip • File clip • Instrument with the display screen • A cord connecting the above three parts. Figure 11.17 shows the photograph of commercially available apex locator and components.

Factors Determining the Accuracy of Apex Locators • Dry and wet conditions of canal: Earlier generation apex locators gave accurate readings only in dry canals. Newer generation apex locators are found to give accurate readings in both dry and wet conditions including the presence of pulp tissue, irrigating solutions and blood.

Fig. 11.17  Apex locator with its components: 1—Lip clip; 2—File clip; 3—Display screen; 4—Cord connecting the above components

• Crown-down preparation of canal: It has been found that preflaring of the coronal portion of the root canals and removal of dentin obstructions from within the coronal access cavity increases the accuracy of the apex locator. • Type and size of file used: The type of file, whether stainless steel or nickel-titanium and the size of file, smaller or larger does not affect the accuracy of the apex locator. • Metallic restorations: It has been found that if the file used with the apex locator contacts the metallic restoration or the fluid in contact with the metallic restoration then the apex locator gives false readings.

Apex Locator and Cardiac Pacemaker Electronic apex locators should not be used in patients with cardiac pacemakers. It requires consultation with the patient’s cardiologist regarding their use in such patients. Advantages and disadvantages of electronic apex locator have been explained in Chapter 14 Cleaning and Shaping of the Root Canal System Including Working Length Determination. A mind-map to remember all points of apex locators is given in Figure 11.18.

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Fig. 11.18  A mind-map to remember electronic apex locators

WHAT ARE THE MATERIALS USED FOR DISINFECTION OF THE ROOT CANAL? Chemical agents for disinfection of root canal include: • Root canal irrigants • Decalcifying materials • Intracanal medicaments. These have been discussed in detail in Chapter 15 Disinfection of the Root Canal System.

WHAT ARE THE INSTRUMENTS AND DEVICES USED FOR ROOT CANAL PREPARATION? Classification of Endodontic Instruments • Grossman has classified the Endodontic instruments according to their function.

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• According to manner of use, Endodontic instruments can be classified as follows. This nomenclature follows the recommendations of the International Organization for Standardization (ISO)

• Cohen has classified Endodontic instruments for root canal preparation into three groups:

HAND-OPERATED INSTRUMENTS ISO Standardization for Root Canal Instruments

• Classification given by ISO-FDI (Federation Dentaire International) according to method of use:

Ingle and Levine gave few specifications for the standardization of root canal instruments which have been revised and also new specifications have been added with the introduction of newer instruments. • Numbering of instruments : Ingle and Levine recommended that the instruments shall be numbered from 10 to 100, the numbers to advance by 5 units to size 60, then by 10 units to size 100. Later smaller numbers such as sizes 6 and 8 and larger numbers to the size 140 also became available. Thus, the standardization is that the instruments are numbered from 6 to 140, the numbers include #6, #8, then from #10 to #60 sizes, numbers advance by 5 units and then from sizes #60 to #140, numbers advance by 10 units. • Diameter of instrument tip: The number of the instrument is representative of the diameter of instrument in hundredths of a millimeter at the tip. For example: No. 6 is 6/100, i.e. 0.06 mm at the tip No. 10 is 10/100, i.e. 0.1 mm at the tip, etc. • The working blade: The working blade begins at the tip, which is an imaginary measuring point designated as Do (or D1) which projects the taper of the instrument at the tip and extends to a length of 16 mm terminating at point D16 (or D2) which represents the diameter at the

Endodontic Armamentarium: Instruments, Materials and Devices

end of the working part of instrument. Thus, the working part of instrument must be at least 16 mm long. A new diameter measurement point D3 was added, according to ADA specification no. 28, D3 is the diameter point 3 mm from the tip of the cutting end of the instrument. Figure 11.19 shows diagrammatic representation of root canal instrument standardization. • Taper of instrument: As per ISO standardization, there was a constant increase in taper of 0.02 mm (2%) per millimeter for every instrument regardless of size. Nowadays, instruments with greater taper such as 0.04, 0.06, 0.08, 0.10 and 0.12 have become popular. It means that with every millimeter increase in the length of the cutting blade, the width (taper) of instrument increases by 0.04, 0.06, 0.08 of a millimeter rather than the ISO standard of 0.02 mm/mm. These new instruments with the increased taper allow for the greater coronal flaring than the 0.02 instruments. Some manufacturers have even made half sizes in the 0.02 flare such as 2.5, 17.5, 22.5, 27.5, 32.5, 37.5. These have been made for shaping extremely fine canals. • Working diameter of instrument: It is the product of the taper and the length of the tip, i.e. The working diameter of an instrument = taper × length of tip = 0.02 × 16 = 0.32 mm greater than the diameter at Do. For example, No. 20 file will have working diameter of: = 0.02 + 0.32 = 0.52 mm • Tip angle of instrument: The tip angle of an instrument is about 75 ± 15o • Length of instrument: Instruments are available in standard lengths of 21 mm, 25 mm, 28 mm and 31 mm. Short instruments are helpful in 2nd and 3rd molars and when patients cannot open the mouth wide and longer instruments are often required for canines. Shorter length instrument such as 19 mm have also become available now.

• Color coding of instrument: Instrument handles have been color coded to recognize them easily. Specific color is given to the numeric diameter at Do. Color code

Instrument number

Pink Gray Purple White Yellow Red Blue Green Black White Yellow Red Blue Green Black White Yellow Red Blue Green Black

#6 #8 # 10 # 15 # 20 # 25 # 30 # 35 # 40 # 45 # 50 # 55 # 60 # 70 # 80 # 90 # 100 # 110 # 120 # 130 # 140

Diameter at Do (mm) 0.06 0.08 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.70 0.80 0.90 1.00 1.10 1.20 1.30 1.40

• Material of instrument : Earlier instruments were manufactured using carbon steel which were susceptible to corrosion usually on contact with sodium hypochlorite solution and were more likely to fracture when strained (deformed). Now, instruments are universally made of stainless steel and nickel-titanium. • Manufacture of instrument: Smaller size finer instru­ ments may break if they bind in the root canal. So, they are manufactured from square blanks to make them resistant to torque fractures. Triangular blanks are used for larger instruments to improve their cutting efficiency. Besides the ISO standards, the instruments and filling materials have been numbered as per the standards given by American National Standards Institute (ANSI) as follows: ANSI number No. 58 No. 63 No. 71 No. 95 No. 57 No. 73 No. 78

Fig. 11.19  ISO standardization of root canal instrument

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Instrument Hedstroem file Rasps and barbed broaches Spreaders and condensers Root canal enlargers Filling materials Absorbent points Obturating points

A mind-map to remember all points of IS O standardization is given in Figure 11.20.

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Fig. 11.20  A mind-map to remember the ISO standardization

Hand Instruments for Root Canal Preparation in Detail Broaches and Rasps • Broaches: – Broaches are of two types—Smooth broach and Barbed broach – Smooth broach does not have barbs and was used earlier as pathfinder. Now flexible files are available for this and smooth broaches are no longer used. – Barbed broaches are short-handled instruments with barbs. – ISO Specification No. 63 sets the standards for barbed broaches. Figure 11.21 shows photograph of barbed broaches. – Barbed broaches have taper of about 0.007 to 0.01 – Broaches are available in different sizes, from extra fine to extra coarse.

Fig. 11.21  Barbed broaches (Courtesy of Mr Amar, Dr Dabholkar’s clinic)

Endodontic Armamentarium: Instruments, Materials and Devices

– Manufacture: Round wire is notched to form sharp barbs bent at an angle from the long axis to manufacture these instruments. – Uses: - For extirpation of vital pulp - For removal of loose debris from necrotic canals - For removal of paper points or cotton pellets from the canals - For enlarging the canals when used in conjunction with sonic or reciprocating handpieces. – Manner of use: A barbed broach should be inserted in the canal only after it has been enlarged to a size no. 25 file/reamer. It is inserted in the canal till the length where it first binds, then rotated to engage the pulp tissue or debris until it meets resistance against the canal walls and then gently withdrawn without twisting. Increased pressure during use may embed the barbs onto the canal walls and increased pressure during its withdrawal from the canal may cause its separation in the canal and it may be almost impossible to remove the separated barbed broach from the canal. • Rasps: – Rasps are similar to barbed broaches with some differences related to taper and barb height. – Rasps have greater taper (about 0.015–0.02) and smaller barbs as compared to Broaches. – Rasps are also used for extirpation of pulp tissue from the root canal. Distinguishing features between broaches and rasps given in Table 11.1.

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Figure 11.22 shows a file stand with Endodontic instruments arranged in sequence.

K-Type Instruments These are named so because they were first designed and manufactured by KERR company. K-type instruments include: • K-Reamers • K-Files • K-Flex files • Reamers: Reamers are k-type instruments. – “Reamers are Endodontic instruments that are used to cut and enlarge the canals by reaming or rotational drilling motion, which means penetration, rotation and retraction”. That means it cuts by inserting in the canal, twisting clockwise one-quarter to half turn and then withdrawing. – Stainless steel wire is ground along its long axis into tapered triangular cross-section (3-sided), i.e. A triangular metal blank is twisted along its long axis to produce a K-reamer (Fig. 11.23). TABLE 11.1  Distinguishing features of broach and rasp Broach • Has larger and fine thickness barbs •  Lesser taper (0.007–0.01) • Barbs present up to half of its core diameter, that makes it a weaker instrument

Rasp •  Has smaller and blunt barbs • Greater taper (0.015–0.02) • Barbs are present only up to 1/3rd of its core

Fig. 11.22  File stand with instruments arranged in sequence. (Courtesy of Dentsply)

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– Cutting action occurs during retraction/withdrawal – Reamers have ½ to 1 cutting blade (flute) per mm of working end – Reaming is the only method that produces a round, tapered preparation in straight root canals, where the reamers are rotated one-half turn. In a slightly curved canal, reamer is rotated only one-quarter turn as more stress may lead to its separation (breakage) – Uses: - Cutting and machining root dentin - Penetrating and enlarging root canals for bringing about shaping or preparation of Root canals. • K-files – Files are Endodontic instruments that are used to enlarge the canals by rasping motion, which means “reciprocal insertion and withdrawal motion”. – Stainless steel wire is ground along its long axis into tapered square cross-section (4-sided), i.e. A square metal blank is twisted along its long axis to produce a K-file (Fig. 11.24). – Cutting action of K-file: The tighter spiral of file establishes a cutting angle, called rake,that achieves its primary action on withdrawal. It can be used in: - Filing (Rasping) motion or push-pull motion: Instrument is placed in the canal till the desired length, pressure is exerted against the canal wall and while maintaining pressure the instrument is withdrawn without turning. The file need not contact all the root canal walls simultaneously, it can be used by filing circumferentially around the walls.

Fig. 11.23  Triangular cross-section of reamer



- Reaming (drilling) motion: Similar to reamer: penetration, rotation and retraction. – K-files have 1 ½–2 ½ cutting blades (flutes) per mm of working end. – Uses of K-files: - Cutting and machining root dentin - Penetrating and enlarging root canals for bringing about shaping or preparation of Root canals. – Few other points about K-files: - Smaller size K-files such as #6 and #8 files do not remove any significant amount of dentin except in severely calcified canals. They are mainly used to establish patency. - Significant wear and loss of efficiency occurs with the repeated use of files. It is recommended that the smaller size files be discarded after one or two uses because initially a point crack develops with its use resulting in metal fatigue in the fragile instrument which causes its distortion and breakage with further use. - Files are generally used in clockwise motion. If they are rotated in counter clockwise direction, they are more prone to fracture. - Copious irrigation should be done in between using Endodontic files to prevent packing of debris in the root canal and files should be lubricated while using in the canal. - After every use, the flutes of the files should be carefully inspected for any distortion or cracks. Distorted files must be discarded otherwise they may break in the root canal. Figure 11.25 shows photograph of reamer No. 30 and K-file No. 30.

K-Reamer

K-file

Fig. 11.24  Square cross-section of K-file

Fig. 11.25  Photograph showing K-reamer and K-file No. 30 (Courtesy of Dentsply)

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TABLE 11.2  Distinguishing features between K-files and K-reamers Distinguishing points

K-files

K-reamers

Manufacture

Stainless steel wire is ground along its long axis into tapered square cross-section (4-sided), i.e. A square metal blank is twisted along its long axis to produce a K-file

Stainless steel wire is ground along its long axis into tapered triangular cross-section (3-sided), i.e. A triangular metal blank is twisted along its long axis to produce a K-reamer

Number of flutes twisted into blade

More number of flutes per length unit (1 ½ to 2 ½ cutting blades (flutes) per mm of working end.)

Less number of flutes per length unit (½ to 1 cutting blade (flute) per mm of working end.)

Nature of flutes

Tighter flutes (1.93–0.88 mm)

Looser flutes (0.80–0.28 mm)

Design feature

Due to square blank, these instruments can resist fracture more effectively than those made from triangular blanks So, square blanks are used for manufacturing smaller, fragile instruments

Triangular blanks are used for larger instruments

Cutting efficiency

Less efficient than reamers

Triangular blanked instruments can cut approximately 2.5 times more efficiently than square-blanked instruments. But they have been found to loose sharpness more rapidly than square ones of same size

Motion of use

• Basically rasping motion, i.e. push and pull motion Penetration and retraction motion for circumferential filing of canals • Can also be used in reaming motion, i.e. penetration, rotation and retraction

• Reaming motion, i.e. penetration, rotation and retraction Rotation within the canal should be only one-quarter to one-half turn

Apical transportation

Chances of transportation are more with a filing motion

Chances of transportation are less with a reaming motion

Apical preparation shape

Usually ovoid

Usually round

Reamers and K-files, both cause compression-andrelease destruction of the root dentin surrounding the canal for enlarging the canals. Although used for same purpose, there are few differences between K-reamers and K-files. These distinguishing features are given in Table 11.2.

K-flex Files • Manufacture: Stainless steel wire is ground along its long axis into rhomboidal or diamond shaped cross-section, i.e. Rhomboidal or diamond-shaped metal blanks are twisted along the long axis to produce K-flex file. • Design: – Rhomboidal shape of blanks having (Fig. 11.26): - Acute angles: Cause increased sharpness and improved cutting efficiency - Obtuse angles: Provide more area for removal of debris – K-flex files have alternate high and low flutes. This design further increases its efficiency in removing debris. • Advantages: – Increased flexibility – Increased sharpness

Fig. 11.26  Rhomboidal shaped blank of K-flex file

– Increased cutting efficiency – K-files have decreased contact with the canal walls thus providing space to facilitate irrigation that reduces the chance of packing debris in the canal. • Flexo files: It is similar to K-flex file but it has triangular cross-section for better flexibility and resistance to fracture and has modified noncutting tip. • Flex R-file/Roane file: – It is made up of nickel-titanium. – It is made by removing the sharp cutting edges from the tip of the instrument (noncutting tip) – It has a triangular cross-section that makes it flexible to be used in curved canals. – The noncutting tip design reduces procedural errors such as ledge formation, canal transportation, etc. when used with balanced force technique.

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H-Type Instruments H-type instruments have a design that facilitates cutting during pulling stroke. Example of H-type instrument is Hedstrom file. • Manufacture: Hedstrom files are manufactured by cutting spiral flutes from a round stainless steel wire. Hedstrom configuration resembles cones or a wooden screw (Christmas-tree pattern). Its flutes appear as successive triangles set one on another. Figure 11.27 shows single helix teardrop configuration of Hedstrom file. Figure 11.28 shows photograph of Hedstrom file No. 30. • Design: – H-type instruments have a more positive rake angle that increases its cutting efficiency. – The blade of these instruments has a cutting rather than scraping angle. • Motion of use: – H-files cut the canal wall when they are rotated clockwise within the canal and pulled. – They are relatively ineffective when pushed or rotated counterclockwise. – Rotational working movements like that of reamers should be avoided with H-files because of the possibility of fracture. • Cutting efficiency: H-type instruments have higher cutting efficiency than K-type instruments. • Instrument fracture: – H-type instruments are fragile and tend to fracture easily. – When a Hedstrom file is bent, there are points of greater stress concentration that can cause propagation of cracks and fatigue failure.

– Improper use of Hedstrom file can cause the instrument to get screwed or locked in the dentin within the canal, which may be impossible to be retrieved. So, the Hedstrom files should not be used in torquing action. • Caution: Considerable thinning of radicular wall even strip perforations can occur with overzealous use of Hedstrom files. • Uses: – Can bring about enlargement or negotiation of small constricted canals and blocked canals. – Can be used to remove gutta-percha fillings from the root canal – Adequate filing strokes can be given with Hedstrom files to remove the overhangs from the canal. • Design modification: “S” file, Unifile and Safety Hedstrom file. – “S” file has double-helix configuration, rather than the single helix teardrop cross-section of Hedstrom file as seen in Figure 11.29. It is stiffer than the Hedstrom file and has good cutting efficiency. – Unfiles: - A modification of Hedstrom file. - Manufactured from round stainless steel wire by grinding superficial grooves in order to produce flutes with a double-helix design. - Less fragile and hence less subject to fracture as compared to Hedstrom files - But they are less efficient. – Safety Hedstrom file has noncutting side to prevent ledge formation in curved canals. The noncutting side is directed to the side of the canal where cutting is not required. Table 11.3 gives the distinguishing features between K-files and H-files.

C+ Files • These are special files made for difficult and calcified canals as they have better buckling resistance than K-files. • Made of stainless steel and have square cross-section. Fig. 11.27  Tear-drop cross-section of Hedstrom file

Fig. 11.28  Hedstrom file No. 30

Fig. 11.29  Double-helix configuration of “S” file

Endodontic Armamentarium: Instruments, Materials and Devices TABLE 11.3  Distinguishing features between K-files and H-files K-type instruments (K-files)

H-type instruments (H-files)

• Have square cross-section • Lesser cutting efficiency when compared to H-files • Rake angle is less positive and blade has scraping angle • Less sharp edges • Less fragile compared to H-file • Motion of use: Rasping motion or reaming motion

• Have round cross-section • More cutting efficiency when compared to K-files • Rake angle is more positive and blade has cutting angle • More sharp edges • More fragile and tends to fracture easily • Motion of use: Slight clockwise rotation (about quarter turn) and retraction

•

•

• Fig. 11.30  Photograph of C+ file (Courtesy of Dentsply)

• Available in sizes of No. 8, 10 and 15 and of lengths 18, 21 and 25 mm. Figure 11.30 shows the photograph of C+ file.

ENGINE-DRIVEN INSTRUMENTS • Engine-driven instruments are used with contra-angle handpiece. Different types of handpieces have been designed for use. • Engine-driven handpieces have been developed for opening of root canals and less preferred for preparation of root canals. • Before using the engine-driven instruments, hand instruments should be used to gain access to apical foramen.

Engine-driven Handpieces • Reciprocating or quarter turn handpiece: – Giromatic handpiece is a commonly used flat plane reciprocating handpiece – It is mounted with latch type instruments that undergo quarter-turn motion at the rate of 3000 times/minute – Broaches, K-type and H-type instruments can be mounted.

•

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– It activates a stainless steel barbed broach or reamer in root canal through a 90 degrees reciprocating arc. – Disadvantages of this handpiece: Packs dentinal debris in the canal, takes longer time and creates ledges and may over-enlarge the apical foramen. It is found to be less effective as compared to hand instrumentation for preparing root canals. The Racer contra-angle handpiece makes use of a standard file and oscillates the file in the root canal. Due to contra-angle design, the instrument length can be adjusted till the working length. But there are more chances of clogging of canal and pushing of debris into the periapical area. M4 safety handpiece: – It has 30 degrees reciprocating motion. – It has a unique chuck that locks regular hand files in place by their handles. – The safety Hedstrom instrument (Kerr company) can be used with this handpiece. The vertical stroke handpiece: – Introduced by Levy – It is either electrically-driven or air-driven – It delivers a vertical stroke ranging from 0.3 to 1 mm. – The more freely the instrument moves in the canal, longer would be the vertical stroke. – This handpiece also has a quarter-turn reciprocating motion along with the vertical strokes. Electric handpieces: Many newer electrical handpieces have been developed to be used with or without motors. In these handpieces, speed and torque can be set. These have been explained later in this chapter along with the nickel-titanium instruments.

Engine-driven Rotary Instruments Most widely used engine-driven rotary instruments include the Gates Glidden drills and the Peeso reamers. A modification of Gates Glidden drill, called Flexogates has been developed, made of nickel-titanium. • Gates Glidden drills: Discussed earlier in this chapter • Flexogates: – Flexogates is the modification of Gates Glidden drill. – It is made up of nickel-titanium. – It is more flexible and can be used for curved canals. – It is rotated in the handpiece through 360 degrees. – It has a safety design with noncutting tip and its weakest part at the neck (about 16 mm from tip), so it can be easily retrieved if fractured. • Peeso reamers: – Instrument design: Peeso reamers have long, sharp flutes on a thick shaft and with a safe tip.

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– Available as 28 mm and 32 mm long instruments. – Peeso reamers are usually available in a set of 6 instruments Peeso 1 to 6, identified by the number of rings on the shank. – Peeso reamers are available in tip diameters ranging from 0.7 to 1.7 mm. The tip diameter of Peeso 1 is 0.7 mm, peeso 2 is 0.9 mm, Peeso 3 is 1.1 mm, Peeso 4 is 1.3 mm, Peeso 5 is 1.5 mm and that of Peeso 6 is 1.7 mm. Figure 11.31 shows photograph of peeso drills 1 to 6. – Cutting action: Peeso reamers have lateral cutting action. – Use: Mainly used for postspace preparation in the coronal portion of the root canal. – Caution: Peeso reamers should be used in a slow speed and in correct angulation to prevent lateral perforations or excessive removal of radicular dentin.

ULTRASONIC AND SONIC INSTRUMENTS Ultrasonic Devices for Endodontic Use • Principle: Sound is used as energy source at 20–25 KHz for the three-dimensional activation of an Endodontic file (K-file) resulting in three-dimensional activation of the file in the surrounding medium. • Mechanism: Two physical actions occur during ultrasonic oscillation namely: cavitation, acoustic streaming. – Bubbles are formed by the free ultrasonic vibration of Endodontic file within the fluid of the canal during negative pressure oscillation and these unstable

bubbles implode with a great force during positive pressure phase of oscillation. This process is called cavitation. Earlier it was thought that the main debriding action of the ultrasonics was by cavitation. Now it is believed that debridement is caused due to the other physical phenomenon called ‘Acoustic streaming’. – Circular fluid movement called Eddy flow occurs around the Endodontic instruments due to acoustic streaming, which is the main mechanism involved in bringing about the cleaning effect of the irrigant in the pulp space. It depends on the free displacement amplitude of the file. • Use: Effective for irrigating the root canal systems for root canal cleaning. When ultrasonic oscillation is used in conjunction with sodium hypochlorite irrigation, it brings about effective root canal disinfection. • Requirements: Free vibration of file within the canal is required for optimum cleansing action with ultrasonic oscillation. So, it is recommended that: For optimum cleansing action with ultrasonic oscillations: – Canals should be enlarged and prepared, i.e. bio­ mechanical preparation of the canals should be completed. – Use a smaller size Endodontic file, such as of size No. 15, that has minimal contact to the walls of the root canal. – Files should be loose in the canal. – Ultrasonic oscillation with an Endodontic file combined with sodium hypochlorite irrigation brings about effective cleaning and disinfection of root canals. • Types: Ultrasonic devices of 2 types can be used: 1. Piezoelectrical. 2. Magnetostrictive. Piezoelectrical unit generates less heat, does not require cooling system and transfers more energy to the file as compared to the magnetostrictive unit and hence are more preferred devices. Figures 11.32A and B show photograph of ultrasonic device and ultrasonic tips respectively for Endodontic use.

Sonic Devices for Endodontic Use

Fig. 11.31  Photograph showing Peeso drills-1 to 6 (Courtesy of Mr Amar, Dr Mukul Dabholkar’s clinic)

Sonics (6 KHz, 8K Hz and 10 KHz) can be used for root canal preparation and disinfection. Example is MM1500 Sonic handpiece that can be used for cleaning, shaping and disinfecting the canal system.

Endodontic Armamentarium: Instruments, Materials and Devices

A

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B Figs 11.32A and B  Ultrasonic device and ultrasonic tips for Endodontic use. (A) Ultrasonic unit for Endo purpose; (B) Ultrasonic tips (Courtesy of Sybron Endo)

This has been explained in detail in Chapter 14 Cleaning and Shaping of the Root Canal System Including Working Length Determination and Chapter 15 Disinfection of the Root Canal System. • Mechanism: Sonically powered files oscillate up and down in a longitudinal oscillation motion to bring about preparation of root canals. • Uses: – Remove pulp remnants and necrotic debris from root canals. – Rasp and remove dentin during preparation of root canals. • Requirements: Sonic instruments should be loose and free to oscillate within the root canal. So, canals should be enlarged to the working length and apical part of root canal prepared using conventional files after which the sonic files are used. • Sonic length: The Sonic instruments, with 1.5–2 mm safe tips, begin their rasping action 1.5–2 mm from the apical stop. This is called ‘Sonic length’. • Examples: – Rispi sonic files – Shaper sonic files – Trio Sonic files of which shaper sonic files are found to be more effective for widening the canals than Rispi Sonic files. But Rispi Sonic files are less aggressive than shaper Sonic files. A mind-map to remember all points of Sonics and Ultrasonics in Endodontics is given in Figure 11.33.

Uses of Ultrasonics and Sonics in Endodontics (Endosonics) • Removes isthmus tissue between canal • Helps in location of orifices • Smoothens the axial walls and floor of the pulp chamber during access cavity preparation finishing • Removes pulp stones smoothly and safely from pulp chamber without scoring • Opens calcified canals • Brings about effective irrigation when used along with sodium hypochlorite and results in cleaner root canals • It can be used for obturation of root canal (Ultrasonicplasticized gutta-percha obturation technique) • Used during retreatment to remove gutta-percha, to remove cement around posts that aids in post removal • It can be used to help retrieve separated files • It can be used for MTA placement in the canals.

NICKEL-TITANIUM HAND AND ROTARY INSTRUMENTS • Nitinol alloys contain 55% nickel and 45% titanium by weight. (Ni—Nickel, Ti—Titanium, NOL—Naval Ordnance Laboratory). • Property of Super elasticity: It is the property of nickeltitanium alloy that allows it to return to its original shape following significant deformation. This property of nickel-titanium makes Endodontic files more flexible, better able to conform to curvatures of canal, resist fracture and wear less than stainless steel instruments.

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Fig. 11.33  A mind-map to remember sonics and ultrasonics in Endodontics



Fig. 11.34  Mind-map of properties of nickel-titanium instruments

Figure 11.34 lists the other properties of nickeltitanium instruments. Root canal preparation with Ni-Ti rotary files is very effective, rapid and safe procedure. But it demands that the clinician understands the: • Root canal anatomy • Principles of use of the selected rotary system. The length, width and the curvature of the root canal needs to be evaluated to decide the strategy for preparation of the root canal. Components of a rotary file: • Flute of file: It is the groove in the working surface of file used to collect soft tissue and dentin chips removed from canal wall.

Endodontic Armamentarium: Instruments, Materials and Devices

• Land: The surface formed in between flutes that projects axially from the central axis. • Cutting/Leading edge: The surface where the flute and land intersect that has the greatest diameter and follows the groove as it rotates is called the cutting edge or blade of file. • Helix angle: It is the angle formed by the cutting edge with the long axis of the file as shown in Figure 11.35. It augers debris collected in the flute from the root canal. • Rake angle: It is the angle formed by the cutting edge with the radius of the file when the file is sectioned perpendicular to its long axis. If this angle is obtuse, it is called positive or cutting and if it is acute, it is said to be negative or scraping. • Pitch of file: It is the distance between a point on the cutting edge and the corresponding point on the adjacent cutting edge as shown in Figure 11.35. When the instrument is designed in such a way that there is balance between the helical angle and pitch of file, there is better cutting action and debris is effectively removed from the canal. Also the instrument is prevented from inadvertently screwing in the canal. Nickel-titanium instruments are superior to stainless steel instruments for Endodontic use. The comparative properties of stainless steel and nickeltitanium instruments are given in Table 11.4.

Fig. 11.35  Components of a rotary Endodontic file: helical angle and pitch

TABLE 11.4  Distin-guishing features between stainless steel and nickel-titanium instruments Stainless steel instruments

Nickel-titanium instruments

• Cannot be used for manufacture of rotary files as: They tend to develop fatal fatigue and fracture after fewer flexural cycles (540° revolutions) • High torque • Rigid • No phase transitions • High modulus of elasticity • Do not show super elasticity and shape memory • Show signs of fatigue/distortion/ deformation before fracture • Less wear resistant

• Widely used for manufacture of rotary files: They can withstand several flexural cycles and may fracture after 2½ full revolutions (900° revolutions) • Low torque • Flexible • Phase transitions • Low modulus of elasticity • Super elasticity and shape memory • Do not show any signs of fatigue before fracture • More wear resistant

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Comparative Properties of Stainless Steel and Nickel-titanium Instruments See Table 11.4.

Phases of Nickel-titanium Alloys

Phase Transformation • • •

On heating, Martensite → R-phase → Austenite This is called forward transformation. On cooling, Austenite → R-phase → Martensite This is called reverse transformation. During Endodontic use: – External stresses cause transformation of Austenitic crystalline phase to martensitic crystalline phase. Martensitic crystalline phase can accommodate stresses without resulting in proportional strain. – When the stress is released, reverse transformation to austenitic crystalline phase occurs and the instrument recovers its original shape in the process.

Manufacture Nowadays, nickel-titanium instruments are precision ground into different designs (K-style, Hedstrom, U files, etc) and made in different sizes and tapers for hand use (manual) or mechanical rotation (Rotary). In addition, Ni-Ti spreaders and pluggers are also available.

Precautions to be Taken While Using Nickel-titanium Instruments See Table 11.5.

Recommended Motions of use for Ni-Ti Rotary Instruments • Research studies have shown that Ni-Ti instruments should be used with rotational or reaming motion and

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TABLE 11.5  Precautions to be taken while using nickel-titanium instruments “Dos”

“Don’t’s”

• Carefully evaluate root anatomy as well as extent and position of canal curvatures from radiographs • Prepare adequate access cavity with straight-line access, prior to using nickel-titanium (Ni-Ti) files • Enlarge and flare the orifices and the coronal 1/3rd of canal adequately before you use Ni-Ti files • Use hand files to negotiate the canal and create a glide path with smaller K-files such as 10, 15, and possibly 20, before using Ni-Ti rotary files. Thus, Ni-Ti rotary files should be introduced in the root canal only after glide path has been established • Discard these files after single use ideally • Measure each file length • Frequently inspect the instruments for any bend or signs of fatigue • Advance nickel-titanium increments passively in the canal • While using Ni-Ti files, as soon as resistance is encountered, stop immediately and before you continue, increase coronal taper and prepare the canal till the working length with smaller size K-files • Lubricate the Ni-Ti files with chelating agent during instrumentation • Irrigation with sodium hypochlorite after use of each file • Recapitulate with smaller stainless steel K-files to ensure patency till length in between use of rotary Ni-Ti files • A pecking, up and down motion with rotary Ni-Ti files is recommended to prevent screwing in of file and to distribute stresses away from the point of maximum flexure of the instrument

• Do not force the file • Do not overuse the files • Do not use Ni-Ti files to bypass the ledges • Do not change the direction of the instrument suddenly by jerky or jabbing move­ments • Do not apply additional pressure if the easily progressing instrument in canal, feels as if it hits bottom • The Ni-Ti rotary file should not remain in the canal for more than 2 to 5 seconds • Do not cause ‘taper lock’ or ‘frictional fit’ of the rotary file within the canal. (When entire length of the file blade is to cut a smaller size canal, the frictional fit of instrument engages root dentin and causes instrument to lock. Rotating the file counter-clockwise will remove it from the canal.) • Do not work in a dry canal • Do not advance larger increment of rotary file into the canal since it may act as a drill and will increase stress on metal • Do not cut with the entire length of the blade

that they are quite effective in shaping the root canal systems. • Ni-Ti files with the design of radial lands can be used as reamers in 360 degrees motion as opposed to traditional reamers with more acute angles. In this, there is a new design of rotary file, in which an identical hand instrument is available. Also, a converter handle is available that allows the operator to use the rotary file as a hand instrument. • Ni-Ti instruments are more efficient and safer when used passively. • Two instrument motions which are recommended include: 1. Gentle pecking motion: Up and down movements 2. Lateral brushing motion: Mainly recommended for Protaper shaping files. According to the American Association of Endodontists (AAE), the “Golden Rules” for Ni-Ti Rotary Preparation include: • Case difficulty should be assessed • Adequate access must be prepared • Preparation with hand files up to size No. 20 prior to use of rotary files, which means glide path must be established with pathfinder files or smaller K-files #10,

#15 and #20 before introducing the Ni-Ti rotary file in the root canal • Use gentle/light touch and low speed (rpm) • Crown-Down sequence should be followed • Replace rotary instruments frequently.

Separation of Nickel-titanium Instruments Cohen classified instrument separation of nickel-titanium rotary files into:

Cyclic Fatigue • When an instrument rotates in a curvature – It gets compressed on inner side of curve, – It gets stretched on outer side of curve.

Endodontic Armamentarium: Instruments, Materials and Devices

With every 180 degrees rotation, instrument flexes and stretches again and again. This results in cyclic fatigue and can cause fracture of the instrument. • Canal curvature and number of rotations determine separation of Ni-Ti files. Rotary Ni-Ti files with larger tapers and sizes tend to fatigue even with fewer rotations. In curved canals, if instrument is worked with high torque, cyclic fatigue occurs. Cyclic fatigue occurs in lateral direction or axial direction. • When the instrument is bound and released during instrumentation into irregularities of canals, cyclic fatigue occurs. • Rigid and larger files are susceptible to cyclic fatigue. (Such files can withstand torsional load) A file with greater taper and larger diameter is vulnerable to fatigue failure.

Torsional Fracture • Nickel-titanium files are low-torque instruments which are quite efficient and safe when used passively. When the torque limit is exceeded, torsional fracture occurs. • Torsional load is transferred into the file through friction against the canal wall that weakens the rotary file causing subsequent fracture. • With the apical movement of the rotary file, torque increases due to increased contact area between the file and canal wall. So, careful passive use of the rotary file as the file advances in the apical portion of the canal, is important. • Torque control motors are available now in which the torque values are set for the rotary instrument. • When there is increased surface area of contact of Ni-Ti files with the walls of the canal, large portion of these tapered instruments get engaged and locked into root dentin. This is referred to as taper lock, which generally occurs when shape of tapered root canal which is being prepared becomes similar to the instrument in use. As a result instrument gets locked in canal and its tip fractures. Such taper lock can also occur in canal irregularities such as where canals, merge or divide. • Fine and flexible files are vulnerable to torsional load. Lower rotational speeds up to 250 rpm can reduce file fractures. Single time use if possible is ideal and can remarkably reduce the fracture of rotary instruments.

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Fig. 11.36  Taper lock of nickel-titanium rotary instrument in the root canal

Other aspects of instrument separation have been discussed in detail in Chapter 20, Endodontic Mishaps: Management and Prevention. Figure 11.36 shows diagrammatic representation of taper-lock of Ni-Ti rotary instrument in root canal.

Advantages of Ni-Ti Instruments • Reduced incidence of clinical problems such as: – Ledge formation – Apical zipping – Stripping or lateral perforations – Canal transportation. • Creates a smooth, tapered canal. • Causes cleaning and shaping in short period of time. Saves clinical time. • Has increased flexibility to negotiate canal curvatures. • Irrigants such as sodium hypochlorite do not cause corrosion or affect the efficacy of Ni-Ti rotary files. • Provides excellent cleaning and shaping if used properly.

Disadvantages of Ni-Ti Instruments • Fatigue resistance reduces significantly after use, especially larger files are found to fail sooner after they have been used. Hence, the need to discard these files frequently. • Also, increase in angle of canal curvature with reduced radius may cause the file to fail sooner. • Increased chances of instrument separation in the canals. • When Ni-Ti rotary files are used with higher rpm, there are more chances of instrument separation and distortion.

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• Tends to cause apical extrusion of debris. • Canals that abruptly curve or merge cannot be easily prepared using Ni-Ti rotary files.

Motors and Devices for Nickel-titanium Rotary Instruments

Fig. 11.37  Motor for rotary instrumentation (Courtesy of Dentsply)

• Electric motors specifically designed to power the rotary nickel-titanium instruments in canal preparation are available. • Newer electric handpieces are available in which there is: speed and torque control The speed and torque are set for a certain instrument and the handpiece will ‘stall’ and reverse if the torque limit is exceeded. • Electric motors with gear reduction ensure a constant rpm level. So, they are more suitable for rotary Ni-Ti system. Example of such an Endo motor is the X-Smart motor (Dentsply), which operates on battery or electric power. Supplied with 16:1 contra-angle. It has a display screen which shows the speed and torque. It also has an auto reverse mode for safety and nine adjustable program selections. Figure 11.37 shows photograph of X-Smart Endo motor. • Various contra-angle torque control reduction handpieces are available, which are very good for beginners and inexperienced clinicians, which can be used with the regular micromotors and airmotors of dental chair. An example of such handpiece is Anthogyr handpiece, which is a contra-angle handpiece that is applicable to all standard nickel-titanium file systems. It allows easy adjustment of the torque by sliding up and down. There are markings 1, 2, 3, 4 to denote Torque values: 0.7, 1.4, 3.2 and 4.5 N.cm respectively. It has microhead which offers maximum visibility and access in the molar areas. Figure 11.38 shows photograph of the Anthogyr Endo hanpiece. • New development is electric handpiece with in-built apex locator. Example is Tri-Auto ZX (J. Morita) which

Fig. 11.38  Anthogyr reduction gear handpiece

is a cordless, battery-operated, Endodontic slow-speed handpiece with in-built apex locator. It has three automatic functions: 1. It automatically starts when file enters the canal and stops when file is removed 2. If too much pressure is applied, automatically handpiece stops and reverses rotation 3. When the file touches the apical stop (As determined by apex locator), the handpiece automatically stops. Currently, electric motors with torque presets are recommended. They reduce the incidence of instrument fracture particularly if the torque settings are low and accurate.

Various Available Nickel-titanium Rotary Instrument Systems Many Ni-Ti instrument systems are being developed and available in the market with different designs.

Endodontic Armamentarium: Instruments, Materials and Devices

Two main factors that impact the shaping potential of Ni-Ti rotary instruments include: Cross-sectional design and tip configuration. All the currently available Ni-Ti rotary systems have noncutting tips. Some rotary systems have radial land areas while some systems have nonlanded design. • Presence of radial lands make the preparation slower but safer. Examples of rotary systems which are radiallanded include: Profile system, Quantec and K3. • Rotary files with nonlanded areas cut rapidly but can lead to preparation errors. Examples of rotary systems which are nonlanded include: Protaper, RaCe. Few of the currently available Ni-Ti rotary systems with their specific design features are given below. The technique and strategy of use of few of them are discussed in detail in Chapter 14: Cleaning and Shaping of the Root Canal System Including Working Length Determination.

Greater Taper (GT) • Cross-sectional design: Three U-shaped grooves, radial lands: Present, rake angle: Neutral • Tip configuration: Noncutting • Taper: Fixed taper 2, 4, 6, 8, 10 and 12% • Recommended speed: 150–300 rpm • Other features: Available in ISO tip sizes of 20, 30 and 40, having a maximum diameter of 1.50 mm. It has variable pitch.

Profile • Cross-sectional design: Three U-shaped grooves, radial lands—present, rake angle—Negative rake angle • Tip configuration: Noncutting • Taper: Fixed taper 2%, 4%, 6% • Recommended speed: 150–300 rpm • Other features: Earlier was available as series of 29 instruments, in which each file increased by 29% instead of 0.05 in between sizes. Has 20 degrees helical angle.

Light Speed Instruments • Cross-sectional design: Three U-shaped grooves, radial lands—present, rake angle—neutral • Tip configuration: Noncutting • Taper: Specific instrument sequence will produce tapered shape • Recommended speed: 750–2000 rpm • Other features: Light speed instruments are slender instruments with thin parallel shaft. Its noncutting tip with unique, short, flame-shaped working end similar in configuration to the Gates Glidden drill.

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Quantec File System • Cross-sectional design: S-shaped design with double helical flutes, radial lands—present, rake angle—positive rake angle • Tip configuration: Both cutting and noncutting tips are available • Taper: Fixed taper 2%, 3%, 4%, 5%,6%,8%,10%,12%. Uses Graduated taper technique. • Recommended speed: 300–350 rpm • Other features: S-shaped design minimizes its contact with the canal, thus reducing the torque. 0.02 tapered files are available in sizes of #15 to #60.

Protaper • Cross-sectional design: Convex triangular cross-section, sharp cutting edges, radial lands—no radial lands, rake angle—positive. • Tip configuration: Noncutting. • Taper: Progressive taper. Variable taper along the length of cutting blades improves flexibility, cutting efficiency and safety. • Recommended speed: 250–350 rpm. • Other features: Has changing helical angle and pitch over cutting blades that prevents instrument from screwing into the canal. Available as 3 shaping files: SX, S1, S2 and 3 finishing files: F1, F2, F3. Explained in detail in Chapter 14: Cleaning and Shaping of the Root Canal System Including Working Length Determination.

Hero 642 • Cross-sectional design: Trihelical Hedstrom design, radial lands—no radial lands, rake angle—positive rake angle • Tip configuration: Noncutting • Taper: Fixed taper 2%, 4%, 6% • Recommended speed: 300–600 rpm • Other features: Available in sizes of #20 to #45. The trihelical, sharp blades are followed by recessive lands that do not extend axially to the circumference, which is designed to reduce stress.

K3 Rotary System • Cross-sectional design: Three asymmetric flutes, radial lands—present, rake angle—positive rake angle • Tip configuration: Noncutting • Taper: Fixed taper 2%, 4%, 6% • Recommended speed: 200–300 rpm

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• Other features: It is similar in concept to Quantec file system. Due to its cross-sectional geometry, these are among the most resistant to fracture. It has variable pitch and variable core diameter.

Reamer with Alternating Cutting Edges (RaCe) • Cross-sectional design: Triangular cross-section, few files have square cross-section. Radial lands—no radial lands, Rake angle—positive • Tip configuration: Noncutting • Taper: Fixed taper 2%, 4%, 6%, 8%, 10% • Recommended speed: 300–600 rpm • Other features: It incorporates alternating nonspiralled and spiralled segments along its working length. This design minimizes torsion of engagement and that resulting from screwing-in forces.

Flex Master • Cross-sectional design: Convex triangular shape, sharp cutting edges, radial lands—no radial lands, Rake angle—positive • Tip configuration: Noncutting • Taper: Fixed taper 2%, 4%, 6%. Intro file has taper of 11% • Recommended speed: 150–300 rpm • Other features: It has individual helical angle for each instrument size. This reduces the screwing-in forces.

Newer Systems

• Spreaders are available as: – Hand-held instruments – Finger-held instruments Finger-held spreaders are preferred because in case of hand-held spreaders the tip of the working end is offset from the long axis of the handle which can cause strong lateral wedging forces on the working end if the instrument is not used carefully. Also, the hand-held spreaders do not have standardized size and shape. Figure 11.39 shows photograph of the finger spreader of size #30 and Figure 11.40 shows photograph of handheld spreader. • Spreaders are available in the sizes of 15–45 and are color coded as per the ISO standardization. Nonstandardized spreaders with larger taper are also available. • Spreaders are made of stainless steel. Nowadays nickel titanium finger-held spreaders are also available that can reach more apically in the canal and useful for penetration in the curved canals due to their flexibility and other properties.

Pluggers • Plugger is an instrument with blunt end used in vertical compaction obturation of gutta-percha. • Pluggers are available as: – Hand-held instruments – Finger-held instruments Finger-held instruments are preferred because the working tip of the hand-held instrument is offset

Revo S system, WaveOne single-file reciprocating system, Reciproc system, Protaper Next system and the latest self-adjusting file system have been explained in detail in Chapter 14: ‘Cleaning and Shaping of the Root Canal System Including Working Length Determination’, along with their techniques of use.

WHAT ARE THE INSTRUMENTS USED FOR OBTURATION OF ROOT CANALS? For Compaction of Gutta-percha

Fig. 11.39  Finger-held spreader for obturation (Courtesy of Dentsply)

The two most commonly used hand instruments during compactions of gutta-percha during obturation include: • Spreaders • Pluggers.

Spreaders • A spreader is a tapered, pointed instrument used in the lateral compaction obturation with gutta-percha to displace gutta-percha laterally to create space for additional accessory gutta-percha cones.

Fig. 11.40  Hand-held spreader for obturation (Courtesy of Dentsply)

Endodontic Armamentarium: Instruments, Materials and Devices

from the long axis of the handle which can cause strong lateral wedging forces on the working end if the instrument is not used carefully. Also, fingerheld instruments provide better tactile sensitivity than the hand-held instruments. Figure 11.41 shows photograph of finger-held plugger and Figure 11.42 shows photograph of hand-held plugger. • Finger pluggers are available in the sizes of 15–140 and are color-coded as per the ISO standardization. Hand plugger does not have standardized size, shape and color. • Pluggers have larger diameter than spreaders and have a blunt end. • Uses of pluggers: – Vertical and lateral compaction of warm guttapercha during obturation. – To carry small sections of gutta-percha into the canal during sectional method of obturation. – To pack materials such as calcium hydroxide and Mineral Trioxide Aggregate (MTA) into the canals. Besides spreaders and pluggers, certain heat carriers are available which transfer heat in the root canal for the apical and lateral displacement of gutta-percha. Commercially available heat carriers include Endotec, Touch ‘N Heat and System B devices. These heat carriers and many other obturation systems have been explained in detail in the Chapter 16: Obturation of Root Canal System.

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For Delivery of Sealers in the Root Canal Sealers can be coated on the walls of root canal using: • Instrument called Lentulo spiral • Bispiral • File or reamer • The master cone itself • Paper points or • Ultrasonic tips.

Lentulo Spiral • Lentulo spiral is used in a slow-speed contra-angle handpiece to deliver the sealer cement into the root canal, i.e. for the application of sealer cement to the root canal walls during obturation. Figure 11.43 shows photograph of a lentulo spiral. • While using lentulo spiral it is important that it is started and stopped outside the root canal otherwise it may cut into the wall of root canal and even break. • The spiral should be large to drive the paste forward so that the material gets squeezed between the spiral and the root canal walls. • Other uses of lentulo spiral: It can also be used to place dressings in the root canal such as calcium hydroxide. Lentulo spiral and bispirals have been explained in Chapter 16: Obturation of Root Canal System.

WHAT ARE THE INSTRUMENTS AND DEVICES USED FOR REMOVAL OF ROOT CANAL FILLINGS AND OTHER OBSTRUCTIONS IN ROOT CANAL? Removal of Gutta-percha

Fig. 11.41  Finger plugger for obturation (Courtesy of Dentsply)

Fig. 11.42  Hand-held plugger for obturation (Courtesy of Dentsply)

Gutta-percha from the root canal can be removed progressively by dividing the root canal into: • Coronal 1/3rd • Middle 1/3rd • Apical 1/3rd.

Fig. 11.43  Photograph showing lentulo spiral (Courtesy of Dentsply)

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Various techniques for removal of gutta-percha are as follows:

Rotary Files

Power-driven Drills

• Currently, rotary instrumentation is the most efficient method for removal of gutta-percha. • Rotary files should be used at low speed (900–1200 rpm) and with caution to prevent file separation. • There is commercially available Endo-Retreatment Kit containing rotary files—D1 D2 D3 in this order having one, two and three rings respectively on their shaft. D1 D2 and D3 are used at the speed of 500 to 700 rpm. Figure 11.44 shows the photograph of these rotary files. – D1 has cutting surface blade of 16 mm, 11 mm handle, one white ring and a taper of 9%. – D2 has cutting surface blade of 18 mm, 11 mm handle, two white rings and a taper of 8%. – D3 has cutting surface blade of 22 mm, 11 mm handle, three white rings and a taper of 7%. – D1, D2 and D3 are used in coronal, middle and apical thirds of the root canal, respectively. Besides this system, there are few other new systems with rotary files for removal of old obturation in case of retreatment.

Such as Gates Glidden drills and Peeso reamers effectively remove gutta-percha from the coronal and straight portion of the root canal.

Ultrasonic Instruments Piezoelectric ultrasonic tips can be used to rapidly remove gutta-percha from the root canals by producing heat that thermosoftens the gutta-percha.

Heated Pluggers • Heated plugger can be used to sear off the gutta-percha from the coronal portions of the root canal. • Another technique involves placing and plunging a heated instrument into the gutta-percha and immediately withdrawing it and then quickly inserting size #35, #40 or #45 Hedstrom file and gently screwing it into the thermosoftened gutta-percha so that it solidifies on the flutes of Hedstrom file and entire or most of the gutta-percha filling comes out with the file. In cases where gutta-percha extends beyond the apical foramen, the above technique can safely remove over-extended gutta-percha. • Specific electric heat carriers also can be used to thermosoften and remove increments of gutta-percha from the root canal.

Chemicals

Fig. 11.44  Photograph showing the rotary Endodontic re-treatment files—D1, D2, D3 in this order used for removal of GP root canal filling (Courtesy of Dentsply)

Gutta-percha solvents include chloroform and xylol. • These solvents chemically soften the gutta-percha that can be removed by sequential instrumentation with K-files or H-files. • Irrigation with chloroform is combined with watchwinding motion use of files that creates space for use of larger files. • Softened gutta-percha comes on the cutting flutes of files as they are withdrawn.

Endodontic Armamentarium: Instruments, Materials and Devices

• The solvent filled canals can be dried using paper points and this is called wicking action which helps to remove the residual sealer and gutta-percha from the root canals. Other details of gutta-percha removal techniques are explained in detail in Chapter 22: Endodontic Failures and Nonsurgical Endodontic Management.

Removal of Silver Points In an old root canal treated case filled with silver point, lateral retention of silver point in the canal might have been reduced due to chronic leakage and corrosion of silver points and if the butt end of silver point is easily accessible in the pulp chamber, then silver point removal is accomplished quite easily. • But most of the times, the butt end of silver point is embedded in the cement, composite or amalgam core. So, the initial access is made with round burs with extended shanks to carefully remove the core material without inadvertently shortening the silver points. • Then ultrasonic instruments can be used to carefully “brush-cut” the core material to expose the silver point which can be then grasped using a suitable grasping instrument such as Steiglitz pliers. • Ultrasonic energy can also be used when silver point lies below the orifice to disintegrate the interface within the canal and enhance the removal of silver point.

Removal of Obstructions from Root Canal such as Separated Instruments

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cement has sufficient strength to withstand the masticatory forces. Temporary cements include:

Cavit • It is a premixed material for use as temporary cement. • Composition: Zinc oxide, calcium sulfate, glycol, polyvinyl acetate, polyvinyl chloride, triethanolamine. • Cavit cement sets as it absorbs fluid. • For adequate seal, it should have depth of at least 3.5 mm.

Intermediate Restorative Material (IRM) • • •

It is a polymer resin-reinforced zinc oxide cement Available as powder and liquid in mixing capsules Its compressive strength is double that of Cavit. It has been found to cause extensive marginal leakage.

TERM • It is light cured filled composite resin which can be used as temporary restoration. • Composition: Urethane Dimethacrylate (UDMA) poly­ mers, inorganic radiopaque filler, pigments, initiators. • Adequate seal can be achieved with it even at the thickness of 1 to 3 mm. Figure 11.45 shows photograph of a commercially available temporary restorative cement.

Various microtube removal techniques have been currently introduced to aid in the removal of the obstruction from the root canal. The Masserann kit, instrument removal system (IRS), endoextractor system (EES) are few commercially available kits that can be used for removal of obstructions such as separated instruments from the root canal.

WHAT ARE THE MATERIALS USED AS TEMPORARY RESTORATIONS? In case of multivisit Endodontic therapy, temporary restorations or cements have to be placed in the access cavity or pulp chamber to achieve a satisfactory coronal seal in order to prevent contamination from the bacteria and fluids from the oral cavity. It is recommended that these cements be placed in the thickness of 4–5 mm for an effective coronal seal and that the

Fig. 11.45  Commercially available ready mixed temporary filling material which sets when it comes in contact with patient’s saliva (Courtesy of Ammdent)

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WHAT IS THE ARMAMENTARIUM FOR PERIRADICULAR SURGERY?

WHAT ARE THE MATERIALS USED FOR POSTENDODONTIC RESTORATION?

For details refer to Chapter 26 Surgical Endodontics. • BP blade no. 15 or microsurgical scalpel • Periosteal elevator • Microexplorer, endoexplorer • Microtissue forceps • Miniature handpieces • Straight handpiece with different burs • Sterile saline • Sterile cotton, cotton pliers • Surgical forceps • Curettes • Root-end filling materials: – Amalgam – Mineral trioxide aggregate (MTA) – Composite resin system (Retroplast) – Intermediate restorative material (IRM) – Super-EBA – Glass ionomer cements – Resin cements such as Diaket • Micromirrors • Microcondensers or microburnishers and pluggers of different sizes • Needle holder, suturing needle, suturing material • Hemostatic agents:

Instruments for Postspace Preparation

↓ Collagen-based –  Collacote –  Collastat

• Peeso drills can be used for postspace preparation • Various postspace preparation drills are available with the preformed post systems. Flow charts 11.1 and 11.2 list the materials used for postEndodontic restoration. They have been discussed in detail in Chapter 21 Restoration of Endodontically Treated Teeth.

WHAT IS THE ROLE OF LASER DEVICE IN ENDODONTICS? Different types of lasers used in dentistry: • Er:YAG laser – Effective for drilling and cutting enamel and dentin. • CO2 laser – Quite effective in soft tissues of oral cavity. But not suitable for drilling and cutting enamel and dentin. Flow chart 11.2  Classification of core materials for restoration of Endodontically treated teeth

↓ Noncollagen based –  Bone wax –  Ferric sulfate –  Gelfoam –  Thrombin

Flow chart 11.1  Classification of post systems for restoration of Endodontically treated teeth

Endodontic Armamentarium: Instruments, Materials and Devices

• Nd:YAG laser – Effective on dark pigmented tissue. • Argon laser – Effective on pigmented or highly vascular tissues.

Applications of lasers in Endodontics: – Laser Doppler flowmetry developed to assess pulpal blood flow to determine vitality of pulp. – Lasers may be used for pulp capping and pulpotomy procedures. – Lasers have been tried in the cleaning and shaping procedures and also in obturation. – Nd:YAG and Er:YAG lasers may be used for removal of old root canal filling materials during Endodontic retreatment.

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– Lasers may be used for root-end preparation during periradicular surgery. Lasers have been explained in detail in Chapter 32 Lasers in Endodontics.

BIBLIOGRAPHY 1. Cohen S, Hargreaves KM. Pathways of Pulp, 9th edn. St. Louis: Mosby; 2006.pp.233-81. 2. Grossman L, Oliet S, Del Rio C. Endodontic Practice, 11th edn. Varghese Publication; 1991.pp.190-6, 210-6. 3. Ingle J, Bakland L, Baumgartner J. Ingle’s Endodontics 6, 6th edn. BC Decker Inc, Hamilton; 2008.pp.800-76. 4. Ingle, Bakland Endodontics, 5th edn. BC Decker-Elsevier; 2002. pp.473-98. 5. “Rotary Instrumentation: An Endodontic Perspective,” Colleagues for Excellence, Winter 2008, American Association of Endodontists.

CHAPTER

12

Asepsis and Sterilization of Endodontic Instruments

This chapter explains the importance of infection control and the various methods to achieve effective infection control in dental practice. It describes the ways to take proper care and about sterilization of various Endodontic instruments.   You must know • Why is Effective Infection Control Important in Endodontics? • How to Achieve Effective Infection Control in Dental Practice? • What is Sterilization and Disinfection? • How to Take Proper Care of Endodontic Instruments? • What are the Commonly Employed Methods of Sterilization/Disinfection of Various Endodontic Instruments?

WHY IS EFFECTIVE INFECTION CONTROL IMPORTANT IN ENDODONTICS? (FIG. 12.1) Asepsis is the state of being free from disease-causing microorganisms or preventing contact with microorganisms. It is necessary to avoid contamination by microorganisms during Endodontic therapy as postoperative infection can be caused by break in sterile technique. Aseptic techniques in Endodontics such as use of sterilized instruments, disinfecting solutions, use of procedural barriers such as rubber dam, etc. is very important to prevent infection.

Fig. 12.1  Goal of infection control

infectious microorganisms from the blood and saliva of patients. For example, influenza, hepatitis B, C, D, upper respiratory disease, herpes, AIDS, etc. So, effective infection control procedures must be used to protect the dental team from contracting infections while delivering dental procedures.

Protection of Patients Protection of Dental Health Care Personnel All dental health care personnel (including both those that are directly involved and those that are indirectly involved in patient care) are at risk for exposure to a wide variety of

Infection should not get transmitted from one patient to other patient due to use of same infected instruments without sterilizing them. The dental team should never be responsible for introducing infection in patients due to lack of adopting appropriate infection control methods.

Asepsis and Sterilization of Endodontic Instruments

Sterile instruments and proper techniques should be used to avoid contamination by microorganisms during Endodontic therapy in order to prevent postoperative infection. Transmission of infection can occur in 2 ways: (Crossinfection)

HOW TO ACHIEVE EFFECTIVE INFECTION CONTROL IN DENTAL PRACTICE? Occupational Safety and Health Administration (OSHA), American Dental Association (ADA), Center for Disease Control (CDC) and other Governmental and NonGovernmental agencies give recommendations for infection control. These guidelines must be followed by the dental team.

Considerations for Dental Operatory • Operatory surfaces such as over-head light handles, X-ray unit heads, dental chair switches and any other surface likely to become contaminated with potentially infectious material should be covered or disinfected. Protective coverings can be in the form of clear plastic wrap, special plastic sleeves, etc. These covers should be changed between patients. • Endodontic microscopes: Handles and controls of microscope should be covered with barriers. Microscope manufacturer’s guidelines should be used for disinfection of microscope. • Sensors of digital radiography are covered with singleuse plastic sleeves for each patient. • Dental unit water lines should be periodically flushed. This can be done with water or a 1:10 dilution of 5.25% sodium hypochlorite to reduce biofilm formation. Biofilm is sticky water line with bacteria, that can travel upstream in dental unit water lines due to slow movement of water. Flushing water lines for 20–30 seconds between patients is recommended to avoid transmission of microbes from one patient to the next. • Waste management: Sharps are included in regulated medical waste category and should be discarded in a rigid container with ‘biohazard’ label. Sharps include

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needles, scalpel blades, Endodontic instruments and other items that can cause injury to skin. Gauze or cotton rolls soaked in blood or saliva are also regulated medical waste and should be appropriately disposed. • It is recommended that there should be separate areas in the operatory for the cleaning/sorting/packaging of contaminated instruments for sterilization. • Aerosols generated during dental procedures can spread throughout the room, so all surfaces need to be disinfected. Doors, drawer pulls should also be covered with barriers or disinfected routinely. • High-volume evacuation can greatly reduce the number of bacteria in dental aerosols and should be used when using high-speed handpiece or ultrasonics.

Considerations for Dental Personnel • Vaccination: All dental health care personnel should be vaccinated against infectious diseases such as hepatitis B, influenza, etc. • Protective attire and barrier techniques: – Protective clothing such as gowns, aprons, lab coats, clinic jackets, either disposable or reusable must be worn. Endodontic surgery will require long sleeved uniforms. Contaminated laundry should not be taken home for wash to avoid transmission of infection to family members. – Protective eyeglasses with solid side shields are required when splashes or sprays of infectious materials are anticipated. – Use of disposable latex or vinyl gloves and masks. Gloves should be replaced after each patient contact. Commonly available masks protect the wearer only partially. Small droplets containing bacteria can pass through them. If the mask becomes wet, it should be changed immediately. Sterile gloves to be worn for surgical procedures. Examination gloves may be contaminated and may harbor microbes. Since gloves do not give total protection, chlorhexidine disinfectant hand wash can be used due to its property of substantivity, it bonds to skin and maintains antibacterial action for longer time as compared to other scrubs. Polyethylene gloves can be worn over treatment gloves to prevent contamination of objects, such as drawers, light handles or patient charts. Figure 12.2 shows photograph of disposable examination gloves, mask and protective eye glasses.

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Considerations Related to the Patient

Fig. 12.2  Disposable examination gloves, mask and protective eye glasses (Courtesy of Mr Amar, Dr Dabholkar’s clinic)

• Patient’s clothing should be protected from splatter and caustic materials with plastic coverings. • Reducing bacteria within oral cavity before treatment by use of appropriate mouthwash such as 0.12% chlorhexidine gluconate. • Use of rubber dam as a protective barrier is mandatory for nonsurgical root canal treatment. • Patient screening: A thorough medical history must be  taken and updated at each visit to include specific questions regarding hepatitis, AIDS, current illnesses, weight loss, etc. Figure 12.3 shows mind-map to remember all points of infection control in dental practice.

Fig. 12.3  A mind-map to remember all points of infection control in dental practice

Asepsis and Sterilization of Endodontic Instruments

WHAT IS STERILIZATION AND DISINFECTION? Sterilization is the process of destroying all life forms, including spores, from an article or surface. Disinfection is the process of destroying most life forms, especially pathogens, but does not include killing spores.

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3. Dry heat: – It utilizes still air in an oven or forced air. – It avoids instrument corrosion. Based on this principle, there are two sterilizers: i. Hot salt sterilizer ii. Glass bead sterilizer. Hot salt sterilizer: It is an efficient and compact apparatus for sterilization of Endodontic instruments.

1. Autoclave: (Moist heat/Pressurized steam) – Commonly used method – Cycle: 250oF temperature (121oC) 15 psi pressure 15–20 minutes – Flash sterilization 273oF (134oC) at higher 30 psi pressure temperatures: 10 minutes Autoclaves are available as: – Top loading – Front loading Figures 12.4A and B show photograph showing commercially available front loading autoclave. 2. Chemiclave: – It utilizes a solution of 72% ethanol and 0.23% formaldehyde in place of water in its autoclave. – It is not suitable for liquids – Temperature of 270oF (132oC) at 20 psi pressure for 20 minutes. – It avoids instrument corrosion.

A

• Components: It consists essentially of a metal cup in which table salt is kept at the temperature of between 425oF and 475oF (218.3oC–246.1oC) Table salt contains: – Sodium silicoaluminate 1% and – Magnesium carbonate/sodium carbonate A thermometer is kept inserted in the salt at all times. • Uses: – Broaches, files and reamers are sterilized by immersion for 5 seconds. – Absorbent points and cotton pellets can be sterilized by immersion for 10 seconds. • Advantages: – Table salt is readily available – Eliminates the risk of clogging the root canal. Thus, the hot salt sterilizer has superseded the moltenmetal sterilizer and glass bead sterilizer. • Disadvantages: – Ineffective in killing spores – Dry heat has poor penetration capability.

B

Figs 12.4A and B  Photograph showing commercially available front loading autoclave (Courtesy of Mr Amar, Dr Mukul Dabholkar’s clinic)

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Glass bead sterilizer: It is an efficient and compact apparatus for sterilization of Endodontic instruments. • Components: It consists of glass beads of less than 1 mm diameter in a metal cup. Large beads cannot transfer heat effectively to Endodontic instruments due to large air spaces between the beads that reduce the efficiency of sterilizer. Figures 12.5A and B show photograph of commercially available glass bead sterilizer. • Temperature: 425–475oF (218–246oC) • Uses: – Broaches, files and reamers are sterilized by immersion for 5 seconds. – Absorbent points and cotton pellets for 10 seconds. 4. Cold chemicals:

A

B Figs 12.5A and B  Glass bead sterilizers. (A) As seen from front; (B) As seen from above. Note the different timings required for sterilization of various instruments are mentioned on the lid (Courtesy of Dr Nishant Singh)

• Recommended only for those items that cannot be heat sterilized. • They usually require extended soak times.

HOW TO TAKE PROPER CARE OF ENDODONTIC INSTRUMENTS? Effective care for Endodontic instruments involves: • Preparation of instruments for sterilization • Sterilization proper • Effective storage of instruments.

Preparation of Instruments for Sterilization Handling, cleaning and packaging of contaminated instruments are frequent sources of injury and possible infection. Reusable instruments that become contaminated after use are immediately taken to a dedicated area for removal of gross debris by scrubbing or by use of ultrasonic cleaner. Clean, dry instruments can then be subjected to sterilization process.

Asepsis and Sterilization of Endodontic Instruments

If immediate cleaning of instruments is not possible then they should be placed in a disinfectant bath to prevent blood, saliva or tissue debris from drying on the surface of instruments because dried material is more difficult to remove. For scrubbing of instruments, heavy puncture-resistant gloves should be worn and long handled brushes should be used to minimize the risk of percutaneous injury. Use of ultrasonic cleaner is more effective and preferable than hand scrubbing. The ultrasonic bath should be covered with a lid to reduce aerosols and should contain a germicide solution, which must be discarded and replaced daily. Figure 12.6 shows photograph of a ultrasonic cleaner. After scrubbing/ultrasonic cleaning, instruments are rinsed under running tap water. These instruments are dried and then wrapped/ packaged for the sterilization process.

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Effective Storage Sterile instruments covered with sterile wrapping should be properly stored in closed cabinets and can be removed and reused when needed. If the wrapping gets exposed to fluids or is not intact, then it should be considered to be contaminated and resterilization is indicated before use. Figure 12.7 shows photograph showing Endo box for effective storage of Endodontic files.

Care of Instruments

Fig. 12.6  Photograph of ultrasonic cleaner

Sterilization Proper Clean, dry instruments can now be made sterile by appropriate methods of sterilization. According to CDC guidelines about sterilizers, instru­ ments should be dried before removing from the sterilizer as wet wraps may tear easily or may allow microbes to reach the sterile contents. In addition, cooling will avoid thermal injury to the personnel.

Fig. 12.7  Photograph showing Endo box for keeping files (Courtesy of Dr Mahashabde, Dr Rajesh Shivhare’s clinic)

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WHAT ARE THE COMMONLY EMPLOYED METHODS OF STERILIZATION/DISINFECTION OF VARIOUS ENDODONTIC INSTRUMENTS? Instrument/material

Method of sterilization/ disinfection

1. Rubber dam

After the rubber dam has been applied it should be thoroughly swabbed with 2% benzalkonium chloride in 50% isopropyl alcohol.   Rubber dam clamp and frame can be sterilized using dry heat, ethylene oxide or autoclave Autoclave Autoclave, or Glass bead sterilizer or Hot salt sterilizer for 5 seconds Swab with tincture of thimerosal followed by alcohol. Swab the surface with tincture of thimerosal Glass bead sterilizer or hot salt sterilizer for 10 seconds 1-minute exposure to 1% sodium hypochlorite or 5-minute exposure to 0.5% sodium hypochlorite or gutta-percha cone

2. Burs 3. Broaches, files, reamers 4. Dappen dishes 5. Glass slab 6. Absorbent points and cotton pellets 7. Gutta-percha cones

Instrument/material

8. 9. 10. 11.

12.

Method of sterilization/ disinfection

freshly removed from the manufacturer’s box is immersed in 5.2% sodium hypochlorite for 1 minute, then rinse the cone with ethyl alcohol and dry it between two layers of sterile gauze Cement spatula Flame it 3–4 times by passing it through bunsen flame Silver cones Slowly passing them back and forth 3–4 times through bunsen flame Diagnostic instruments Autoclave mouth mirrors, probes, explorers, tweezers Long-handle Dipping the working end instruments tips of in alcohol, passing through cotton pliers, scissor the flame 2–3 times blades Local anesthetic Presterilized with ethylene Cartridges, needles oxide and are disposable

BIBLIOGRAPHY 1. Cohen S, Hargreaves KM. Pathways of Pulp, 9th edn. St. Louis: Mosby; 2006.pp.98-101,136-47. 2. Grossman L, Oliet S, Del Rio C. Endodontic Practice, 11th edn. Varghese publication. 1991.pp.136-41.

CHAPTER

13

Endodontic Access Cavity Preparation

This chapter discusses in detail the first step of Endodontic treatment, i.e. access cavity preparation of root canal and explains how Endodontic success greatly depends on a good access.   You must know • What is Endodontic Triad? • What is Coronal Access Cavity Preparation of the Root Canal? • What are the Objectives of Access Preparation? • What are the Principles of Endodontic Access Cavity Preparation? • What are the Guidelines to be Followed for an Optimum Access Cavity Preparation? • What is the Armamentarium Needed for Access Cavity Preparation? • Which are the Steps of Access Cavity Preparation? • What are the Specific Features of Access Preparation of Individual Teeth and Possible Errors Related to Them? • Which are the Challenging Access Cavity Preparations and How to Deal with them? • What Errors can Occur During Access Cavity Preparation?

WHAT IS ENDODONTIC TRIAD? The Endodontic treatment (Root canal treatment) can be accomplished in three main phases commonly referred to as the ‘Endodontic triad’, which includes:

• Coronal Access cavity preparation (This chapter) • Cleaning and Shaping of the Root Canal, i.e. Biomechanical Preparation of Root Canal (Chapter 14) • Irrigation and Disinfection of the Root Canal System (Chapter 15) • Obturation of the Root Canal System (Chapter 16).

WHAT IS CORONAL ACCESS CAVITY PREPARATION OF THE ROOT CANAL?

We shall study each of these phases in detail in the following chapters:

After establishing an accurate diagnosis and proper case selection, the first phase of Endodontic treatment directly applied to the tooth is “access cavity preparation”, also referred to as “Endodontic entry”. Undoubtedly, a good beginning is essential to achieve a good end result. Thus, a well-designed access cavity preparation is a must to achieve a good Endodontic result.

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Definition “The preparation extending from the occlusal table to the canal orifices that facilitates smooth, unobstructed, straightline path to the canal system and ultimately to the apex is called coronal access cavity preparation of the root canal”. A well-designed access preparation will allow: • Thorough cleaning and shaping • Complete irrigation and disinfection • Quality obturation.

WHAT ARE THE OBJECTIVES OF ACCESS PREPARATION? The objectives of access preparation are given in Figure 13.1. It is important to understand that: • Access cavity preparation should be – Wide enough: - To facilitate visibility and ease of handling instruments in highly complex root canal system - To locate all root canal orifices and smoothly negotiate all root canals – Conservative enough: - Preserving sound tooth structure to improve tooth’s fracture resistance - To increase its structural integrity and long-term prognosis. Unnecessary tooth structure removal should be avoided. • Access cavity preparation is specific and unique for each tooth and each patient. Standard protocol is followed for making initial entry but extension of access preparation varies for individual tooth considering various factors as given in Figure 13.2.

Fig. 13.1  Objectives of access preparation

WHAT ARE THE PRINCIPLES OF ENDODONTIC ACCESS CAVITY PREPARATION? Principles of Access Cavity Preparation • Outline form: “Outline form is that form of the area of the tooth surface to be included within the finished margins of the Endodontic access cavity preparation.” – The outline form of the access preparation is dictated by the internal anatomy of the tooth. The preparation is extended from inside to outside. – The access cavity design is primarily dependent on the anatomic position of the orifices. – Size and shape of the pulp chamber also determines the outline form. – The access preparation should be such that the pulpal roof including all overlying dentin is removed. – It resembles the inlay cavity preparation with the walls diverging occlusally. – Factors to be considered for access cavity design are given in Figure 13.2. Besides these factors, whenever required, the access preparation needs to be extended to eliminate any other restrictive interference in the straight line path to the apical portion of the canals.

Shamrock Preparation In case of extremely curved canals, the access preparation needs to be extended at the expense of coronal tooth structure so that the instrument can be accommodated unrestrained in the canal and there is straight line access to the apical foramen. Such a modified outline form of the access preparation is called as Shamrock preparation. It has been demonstrated in Figure 13.3.

Fig. 13.2  Factors affecting extension of access preparation

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Figs 13.3A and B  (A) Dentinal shelf obstructing the straight-line access, dotted line shows the required extension; (B) Shamrock preparation that provides straight-line access (SLA) to the apex

Figs 13.4A and B  (A) Mouse-hole effect; (B) Correcting the mouse hole effect and optimum extension of access preparation

Access preparation needs to be extended at the expense of coronal tooth structure shown by dotted line in Figure 13.3A for unrestrained access of instrument—Shamrock preparation (Fig. 13.3B) • Convenience form: “Convenience form is that form of the access cavity preparation that allows adequate observation and unobstructed access of Endodontic instruments into the canal orifices and ultimately to the apical foramen.” – The overhanging roof of the pulp chamber needs to be removed so that the orifices can be easily located and visualized. – The walls of access preparation should be made smooth and occlusally diverging so that the instrument can freely slide down the orifices into the canals. – Root curvatures and the angle at which the canal leaves the pulp chamber should be considered and the access preparation modified accordingly.

orifice. This will eliminate the mouse-hole and the orifice will now be entirely on the pulpal floor. Figure 13.4A shows under extended access preparation with mouse hole effect. Figure 13.4B shows correcting the mouse hole effect and optimum extension of access preparation.

Mouse-hole Effect

Visualization of the Likely Internal Anatomy

Orifices should be located at the corners of the preparation and entirely on the pulpal floor and not into axial walls. If the orifice extends into axial walls it will appear as tiny “mouse-hole” and indicates that the access cavity is underextended. In that case, the lateral wall of the cavity should be extended so as to remove the overlying dentin from the

Figure 13.5 shows the mind-map that gives details of visualization of the likely internal anatomy. Figure 13.6 shows the diagrammatic representation of how the depth of pulp chamber can be estimated by keeping the handpiece with the bur alongside a preoperative radiograph.

WHAT ARE THE GUIDELINES TO BE FOLLOWED FOR AN OPTIMUM ACCESS CAVITY PREPARATION? • Guidelines: Let us consider the 10 guidelines given in Cohen’s Pathways of Pulp, 9th Edition, as Golden rules for the completion of an optimum access preparation and remember them with the help of following sentence: Very Easy Preparation Requires Root Canal Details to be Learnt and Implemented Throughly, i.e. Visualize, Evaluate, Prepare, Remove, Remove, Create, Delay, Locate, Inspect, Taper.

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Fig. 13.7  First law of symmetry

Fig. 13.5  Mind-map showing details of visualization of the likely internal anatomy

Fig. 13.6  Estimation of depth of pulp chamber by keeping the handpiece with the bur alongside a preoperative radiograph

Evaluation of the Cementoenamel Junction and Occlusal Anatomies One cannot rely completely on occlusal anatomy to prepare the access cavity as the crown might have been destroyed by caries or reconstructed with restorative materials, thus there can be a change in the morphology of the tooth. According to studies by Krasner and Rankow, cementoenamel junction (CEJ) is the most important landmark for determining the location of pulp chambers and root canal orifices. They found that anatomy of pulp chamber floor is specific and consistent and they have given the following guidelines or laws of pulp chamber anatomy to help

clinicians determine the number and location of orifices on the pulp chamber floor: • Law of Centrality: The pulp chamber floor is always located in the center of the tooth at the level of the CEJ • Law of Concentricity: The pulp chamber walls are always concentric to the external surface of the tooth at the level of the CEJ, which means, the external root surface anatomy reflects the internal pulp chamber anatomy. • Law of the CEJ : At the level of the CEJ, the distance from the external surface of the clinical crown to the wall of the pulp chamber is the same throughout the circumference of the tooth. The CEJ is the most consistent, reproducible landmark for locating the position of the pulp chamber. • First law of symmetry: Canal orifices are equidistant from a line drawn in mesiodistal direction through the pulp chamber floor. Exception is maxillary molars. Figure 13.7 shows schematic representation of the first law of symmetry. • Second law of symmetry: Canal orifices lie on a line perpendicular to a line drawn in a mesiodistal direction across the center of pulp chamber floor. Exception is maxillary molars. Figure 13.8 shows the schematic representation of the second law of symmetry. • Law of color change: The color of the pulp chamber floor is always darker than the walls. • First law of orifice location: Orifices of root canals are always located at the junction of walls and floor. • Second law of orifice location: Orifices of root canals are located at the angles in the floor-wall junction. • Third law of orifice location: Orifices of root canals are always located at the terminus of roots’ developmental fusion lines.

Preparation of the Access Cavity Through Lingual and Occlusal Surfaces Access cavity is prepared through the lingual surface in anterior teeth and the occlusal surface in posterior teeth. (Fig. 13.9).

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Fig. 13.8  Second law of symmetry

Fig. 13.10  Mind-map of details of removal of caries and defective restorations

Fig. 13.9  Mind-map to remember the starting point (surface) for access cavity preparation

Incisal approach in case of mandibular anterior teeth improves access to the lingual canal and allows for complete canal debridement.

Removal of all Defective Restorations and Caries Before Entry into Pulp Chamber Figure 13.10 shows the mind-map explaining why all the caries and defective restorations should be removed before entry into pulp chamber.

Removal of Unsupported Tooth Structure Figure 13.11 shows mind-map of details of removal of unsupported tooth structure.

Creation of Access Cavity Walls that do not Restrict Straight or Direct-line Passage of Instruments to the Apical Foramen or Initial Canal Curvature— Straight-line Access “Straight-line access (SLA) describes a preparation that provides a straight or outwardly flared, unimpeded path from the occlusal surface to the apex.” (Ingle’s Endodontics 6, pp.878-879) SLA allows Endodontic instrument (file) to reach the apex with minimal deflection. In order to obtain SLA, coronal tooth structure removal may be needed

Fig. 13.11  Mind-map of details of removal of unsupported tooth structure

sometimes on buccal and lingual surface in addition to the mesial and distal surface especially in case of curved canals. Also, it involves selective removal of outer canal tooth structure in order to protect the furcal surface. Figure 13.12 gives the mind-map showing details of SLA.

Delay of Dental Dam Placement Until Difficult Canals have been Located and Confirmed Figure 13.13 shows mind-map showing until when the dental dam placement to be delayed.

Micro-openers are excellent instruments for locating canal orifices when a dental dam has not been placed. Micro-openers have –  #0.04 and #0.06 tapered tips –  Offset handles

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Fig. 13.14  Mind-map explaining location, flaring and exploring root canal orifices

Fig. 13.12  Mind-map giving details of creating access cavity walls to get straight-line access Fig. 13.15  DG-16 Endodontic explorer for locating the canals

Fig. 13.13  Mind-map to show delaying dental dam placement

These flexible, stainless steel hand instruments provide enhanced visualization of the pulp chamber.

Location, Flaring and Exploration of all Root Canal Orifices Figure 13.14 shows mind-map that explains details of this. Figure 13.15 shows diagrammatic representation of DG16 Endodontic explorer. Figure 13.16 shows photograph of GG drills no. 1 to 6 used for flaring of root canal orifices. Figure 13.17 shows photograph of K-files no. 6, 8, 10 used for exploring the canals. ( Remember PGPu Pink, Gray, Purple) Figure 13.18 shows photograph of commercially available EDTA gel for lubrication.

Inspection of Pulp Chamber Using Magnification and Adequate Illumination Figure 13.19 shows mind-map giving details of this.

Fig. 13.16  GG drills no. 1 to 6 used for flaring of canal orifices (Courtesy of Mr Amar, Dr Dabholkar’s clinic)

Tapering of Cavity Walls and Evaluation of Space Adequacy for a Coronal Seal A properly prepared access cavity has Tapering/Diverging Walls that is widest at the occlusal surface. It is recommended to place a temporary filling material of at least 3.5 mm depth to provide an adequate coronal seal in between appointment so as to reduce the risk of bacterial contamination.

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Fig. 13.19  Mind-map giving details of inspection of pulp chamber

Fig. 13.17  K-files 6, 8, 10 (Courtesy of Dr Shivani Bhatt)

Fig. 13.18  EDTA gel (Glyde) for lubrication (Viscous chelator) (Courtesy of Dentsply)

Fig. 13.20  Temporary filling

Temporary filling: • The access cavity should be sealed with a temporary filling material between visits in case of multivisit approach so as to prevent the contamination of the root canal system by saliva with its bacterial flora and food particles and to prevent any intracanal medicament from leaking. • Requirements of an ideal temporary filling material: – It should seal the cavity peripherally and be impervious to bacteria and the oral fluids – It should set in few minutes after insertion into the cavity. – It should withstand the mastication forces. – It should be easy to manipulate – It should be easy to remove. • The most commonly used temporary filling material is zinc oxide eugenol cement which provides a good seal. But it lacks the strength to withstand the masticatory forces and is slow-setting and its deformation while setting may contaminate the root canal system. 0.5 to

1% zinc acetate is added to accelerate the setting time of zinc oxide eugenol and prevent its distortion. For greater surface hardness, polymer-reinforced zinc oxide eugenol called intermediate restorative material (IRM) can be used. • Zinc-oxide polyvinyl preparation, commercially available as Cavit, can also be used as a temporary filling material. It is a hydrophilic compound that sets in the presence of moisture. Its use in vital teeth should be avoided as it may dessicate dentin causing sensitivity in the teeth. • To prevent leakage, the thickness of temporary filling material should be about 3–4 mm. • A dual filling (double seal) is advisable which consists of a medicated cotton pellet sealed in the pulp chamber by an inner seal of temporary stopping and an outer seal of zinc oxide eugenol, IRM or Cavit. Figure 13.20 shows the diagrammatic representation of a temporary filling. The single seal uses a medicated cotton pellet in pulp chamber covered by dry cotton pellet and sealed with zinc oxide eugenol, IRM or Cavit.

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WHAT IS THE ARMAMENTARIUM NEEDED FOR ACCESS CAVITY PREPARATION? • Magnification using dental operating microscope (DOM) or surgical loupes (2.5X, 4X) can be really helpful. Figure 13.21 shows schematic representation of the dental operating microscope (DOM). Figure 13.22 shows schematic representation of a magnifying loupe. (The dental operating microscope (DOM) and the magnifying loupes have been described in detail in Chapter 11: Endodontic Armamentarium: Instruments, Materials and Devices). • Handpieces: – High speed handpiece: For initial penetration – Slow speed handpiece: For deeper penetration and in case of calcified and receded pulp chamber. • Burs: (Fig. 13.23): – For removal of caries, initial penetration and deroofing the pulp chamber - Round carbide burs (Medium sizes such as # 2, # 4).

- Round diamond burs (for access through porcelain) - Long shank round burs - Transmetal burs for penetration through metal - Tapered fissure carbide bur or a diamond bur with rounded cutting end – For axial wall extensions - Safe-ended diamond and tungsten carbide burs (tip/end is noncutting, sides are cutting), for example, endo access bur, endo Z bur (Figs 13.24A and B), safe nonend cutting bur These can be used for final refinement extending from enamel to the pulp floor orienting the axial walls without causing gouging.

Fig. 13.23  Access preparation bur kit showing round bur, transmetal bur, long shank round burs, safe-ended Endo Z bur and X-gates (Courtesy of Dentsply)

Fig. 13.21  Dental operating microscope (DOM)

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Fig. 13.22  Magnifying loupe

Figs 13.24A and B  (A) Endo access bur; (B) Endo Z bur (Courtesy of Dentsply)

Endodontic Access Cavity Preparation

– For enlarging the orifices and flaring of coronal portion of the root canal and blending of the orifices into the axial walls in order to gain straight-line access (SLA), Gates Glidden burs can be used. Gates Glidden drills/burs cut laterally in a selective manner so that excess removal of furcal dentin is avoided. See Figure 13.16 for Gates Glidden drills -1 to 6 GG burs 1 to 6 and GG X: GG 1 (ISO size # 50) GG 2 (ISO size # 70) GG 3 (ISO size # 90) GG 4 (ISO size # 110) GG 5 (ISO size # 130) GG 6 (ISO size # 150) GG X (Features of GG 1 to GG 4) Figure 13.25 shows schematic representation of X gates that has combined features of GG 1 to GG 4. It has no ring on its shank. Figure 13.23 shows photograph of X gates. • Hand instruments: – DG-16 Endodontic explorer: To locate root canal orifices and to determine canal angulation – Endodontic spoon excavator: To scoop out carious dentin and to remove coronal pulp Figure 13.26 shows diagrammatic representation of DG 16 Endodontic explorer and Endodontic spoon excavator. • Ultrasonic unit and various ultrasonic tips: Can be useful for exploring the root canal orifices by troughing and deepening the developmental grooves to remove the tissues with minimal collateral tooth structure removal. Figure 13.27 shows commercially available Endodontic ultrasonic tips.

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WHICH ARE THE STEPS OF ACCESS CAVITY PREPARATION? The general sequence of steps to be followed for access cavity preparation are as follows: Step 1: Removal of caries and existing restorations if any: Penetration of enamel through lingual surface in case of anterior teeth and through occlusal surface in case of posterior teeth using the appropriate size round bur, the size smaller than the size of the pulp chamber of the tooth. Figure 13.28 shows the diagram of initial entry made through lingual surface in anterior tooth perpendicular to the long axis of tooth.

Fig. 13.27  Commercially available Endodontic ultrasonic tips— Start X (Courtesy of Dentsply)

Fig. 13.25  Schematic representation of X Gates. GG X has combined features of GG 1 to GG 4. It has no ring on its shank

Fig. 13.26  DG-16 Endodontic explorer and Endodontic spoon excavator

Fig. 13.28  Initial entry through the lingual surface in anterior teeth with the round bur perpendicular to the long axis of tooth

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In case of access through the crown, use of round diamond bur for access through porcelain and transmetal bur for access through metal. It is recommended to use a new sharp bur and cut the dentin in a light brushing motion to reduce the heat produced. Step 2: Penetration of roof of pulp chamber: Keeping the bur parallel to the long axis of the root all the time in case of anterior teeth and premolars as shown in Figure 13.29A. In case of molars, the penetration angle is towards the largest canal as shown in Figure 13.29B.   A sudden sinking of the bur or “drop in” effect is felt as soon as the roof of the pulp chamber is penetrated. But in case if the pulp chamber is deep or calcified, such a feeling of drop may not be felt. So, it is important to evaluate the preoperative radiograph and measure the distance between the cusp tip and the roof of the pulp chamber. The penetration should be carefully limited to this distance. Step 3: Complete removal of roof of the pulp chamber: Once the pulp chamber roof has been penetrated, stop pushing the bur, now withdrawal movement has to be carried out in order to deroof the pulp chamber completely. Brush cut against the roof as if lifting the bur against the edge of the roof till the entire roof is removed. This allows the internal pulp anatomy to dictate the external outline form of the access opening.   Ruddle recommends that in case of bleeding vital pulp, at this step, the pulp chamber be filled with viscous chelator such as EDTA to bring about emulsification of vital pulp tissue and to hold

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the pulp remnants, dentinal mud and debris in suspension.   Figure 13.30 shows the withdrawal movement to deroof the pulp chamber.   In case of necrotic pulp, the pulp chamber be filled with 5.25% warm sodium hypochlorite. Step 4: Axial wall extension: Is done at this step in order to achieve a good convenience form. Tapered fissure carbide or diamond bur with rounded end or safeended diamond or carbide burs are used to funnel the corners of the access cavity directly into the orifices and to plane the axial walls and slightly flare them towards the occlusal.   Figure 13.31 shows diagram demonstrating axial wall extension in maxillary molar.

Fig. 13.30  Deroofing the pulp chamber using round bur in withdrawal movement from inside of the pulp chamber to the outside

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Figs 13.29A and B  (A) After penetration of enamel the bur is held along the long axis of the tooth till the pulp chamber is reached; (B) In case of molars, the penetration angle is towards the largest canal

Fig. 13.31  Axial wall extension in maxillary molar

Endodontic Access Cavity Preparation



  Access preparation should have occlusally divergent smooth axial walls resembling inlay cavity preparation in order to remove all the obstructions hindering the straight-line access to the canals. Also smooth and diverging walls enhance vision by improving the refraction of light. Step 5: Identification of all root canal orifices: After complete deroofing of the pulp chamber, an Endodontic explorer (DG-16) can be used to locate the root canal orifices if there is adequate radicular space. As the tip of the Endodontic explorer is placed into the orifice, the portion of the shaft is checked for clearance from the axial walls. It may also give an idea about the angle at which the canal leaves the pulp chamber. If there is inadequate radicular space to allow the entry of Endodontic explorer, then a small-sized hand file can be gently inserted into the coronal portion of the canal to determine the entry angle of the canal relative to the long axis of tooth.   In posterior teeth, the extension of the outline form of access cavity should be such that the orifices are located at the corners of the preparation and entirely on the pulp floor and should not extend into an axial wall. If the orifice extends into an axial wall, it indicates that the access cavity is underextended and it creates a mouse-hole effect that impedes the straight-line access (SLA).   Knowledge of the anatomic location of the orifices and the possibility of finding additional canals should be kept in mind while identification of orifices.   In case of calcified root canal, orifice location may cause difficulty. For such cases: Orifice location aids: • Carefully read multiple pretreatment radiographs (atleast three preoperative radiographs) • Use of sharp explorer to examine the pulp chamber floor. Multiple canal orifices can be explored effectively using an Endodontic explorer • Ultrasonic tips can be helpful for troughing the grooves and relocating the orifices. • Color: Walls of pulp chamber are white or light yellow in color. Floor of the pulp chamber and the grooves connecting the orifices are dark brown or gray in color. • “Champagne Bubble” Test (Fig. 13.32): Sodium hypochlorite (NaOCl) is allowed to remain in the pulp chamber for some time. Tiny bubbles may appear in the solution. This indicates the position of root canal orifice.

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Fig. 13.32  Champagne bubble test

• 17% EDTA and 95% Ethanol can be applied sequentially for effective cleaning and drying of the floor of the pulp chamber. This makes it easier to visualize the orifices. Step 6: Removal of internal impediments to straight-line access or restrictive shelf of dentin, i.e. lingual shoulder and cervical dentin bulge. • In case of anterior teeth, a lingual shelf of dentin exists called as lingual shoulder from cingulum of the tooth to a point about 2 mm apical to the orifice.   Removal of lingual shoulder aids in straightline access (SLA).   Lingual shoulder can be removed using tapered safety tip diamond or carbide bur or with Gates Glidden burs. During rotation, the GG bur must be leaned gently, against the lingual shoulder and withdrawn as shown in Figure 13.33. • In case of posterior teeth, shelves of dentin that frequently overhang the canal orifices are called as cervical dentin bulges.   Removal of cervical bulge aids in straight line access (SLA)   Cervical dentin bulges can be removed using tapered safety tip diamond or carbide bur or with Gates Glidden burs. GG burs are used by gently leaning towards the dentin bulge in sweeping upward motion with lateral pressure away from the furcation to remove the overhanging shelf.   Sometimes secondary dentin may be overlying the orifices and obscures it. Long shank round bur can be used to remove it.

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Fig. 13.33  Removal of lingual shoulder



  If a small file such # 10 K-file is inserted into the canal through the orifice, it is important to obtain uniform contact of file within the access cavity. If the file is being deflected or held up by any restricting or restraining dentin in the access cavity or in the coronal portion of the root canal, then it should be removed to cut a “relief channel” through which the file can contact the dentin evenly along its length without undue strain. This can be done by using thin needle diamond bur or safety tip diamond bur to relieve that area of access cavity wall and by using smaller GG burs to relieve the restraining dentin in the coronal portion of the canal. Step 7: Preflaring the orifice, coronal relocation and removal of triangles of dentin: All of these processes can be accomplished using GG drills. • Preflaring the orifice: – Root canal orifices should be flared and made contiguous with the walls of the access cavity preparation. – For adequate cleaning and shaping, the orifices can generally be enlarged to a diameter of 0.9 to 1.1 mm without causing undue loss of root strength. – The procedure of orifice flaring is also referred to as “facing-off” the orifices. – A larger size GG drill such as no. 3 or no. 4 which passively fits into the orifice is selected. – Notice the GG drill/canal orifice pivot point and move the head of the hand piece in an orbital arc above this pivot point. The belly of the GG drill enlarges the orifice and facilitates the entry of smaller size GG drill, i.e. no.

2 or no. 3 to be used in gentle “pecking” motion or “brushing” action. This is to enlarge the coronal one-third of the canal by removing the dentin on the outstroke. Then sequentially no. 2 and no. 1 GG drills can be used in the straight portion of the canal. No. 4 GG drill is used to the depth such that only its flame shaped bud is below the orifice. – Orifices can also be flared using rotary nickeltitanium orifice openers to be used at slow speed and low torque. • Coronal relocation: – The purpose of the coronal relocation is to center the radicular preparation within the circumferential dimension of the root, so as to prevent the thinning of the root that may predispose it to radicular fracture or strip perforations. – In case of multirooted teeth, the coronal portion of the canal has to be intentionally relocated away from the furcal danger. – Also in teeth with external root concavities, the radicular preparation has to be directed towards the greater bulk of the dentin away from these concavities. – This is accomplished by using the GG drill in an orbital arc above the GG drill/canal orifice pivot point in the direction of the name of the canal as shown in Figure 13.34. • Removal of internal triangles of dentin: – In some roots, an internal triangle of dentin may hinder the straight line access of the Endodontic instrument to the apical portion of the canal.   Figure 13.34B shows the diagrammatic representation of internal triangle of dentin hindering the straight line access. – Use of GG drills removes the internal triangle of dentin (Fig. 13.34C). Step 8: Determination of straight-line access (SLA): A small Endodontic file such #10 K-file, when inserted in the root canal orifice should have unimpeded access to the apical foramen or first point of canal curvature to facilitate proper cleaning and shaping, as shown in Figure 13.34D.   It should have uniform even contact with the walls and smooth glide path.   Gently insert the file and withdraw it and feel if there is canal binding or deflection. If the handle of small sized file is off the long axis of tooth, it suggests that there may be an internal triangle of dentin that needs to be removed to achieve SLA.

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Figs 13.34A to D  Removal of internal triangle of dentin. (A) Mandibular molar in which access preparation is to be done; (B) Diagrammatic representation of internal triangle of dentin hindering the straight line access; (C) Gates Glidden drill is used to remove the internal triangle of dentin; (D) Straight-line access to the apical foramen after removal of internal triangle of dentin

• When there is SLA: There is better tactile sensation to feel the root canal anatomy and to feel how the file performs in root canal system. This allows all the areas of canal to be cleaned and shaped effectively. • When there is no SLA: Procedural errors such as—ledge, transportation, zipping, instrument separation, etc. can occur. Step 9: Careful evaluation of the prepared access cavity: Under good illumination and magnification using dental operating microscope (DOM) and magnifying loupes, the access cavity should be inspected carefully.   Additional canals may be located, that should then be cleaned and shaped.   After preparing the access cavity, when you view it using a mouth mirror, without moving the mouth mirror if all orifices can be visualized, then the access cavity is said to be adequately prepared. If you have to move the mirror to view the orifices individually, then it means that the access cavity is underprepared and you need to extend it further. Step 10: Refinement and smoothing the cavosurface margins: The access cavity preparation should have smooth, diverging axial walls that allow smooth sliding down of the instruments into the preflared orifices.   After using GG drills, a surgical length tapered diamond can be used to refine the access cavity.





  Also, if the cavosurface margins are rough and irregular, coronal leakage occurs through temporary or permanent restoration. Refinement and smoothing of cavosurface margins helps improve the coronal seal.   Figure 13.35 shows a mind-map to remember steps of access preparation.

WHAT ARE THE SPECIFIC FEATURES OF ACCESS PREPARATION OF INDIVIDUAL TEETH AND POSSIBLE ERRORS RELATED TO THEM? Maxillary Anterior Teeth Steps of Endodontic access cavity preparation for maxillary anterior teeth are shown in Figures 13.36A to E.

Maxillary Central Incisor • External access outline form: Rounded triangle with incisal aspect forming the base of the triangle and the mesial and distal external walls converging towards the cingulum as shown in Figure 13.37. The internal walls must funnel towards the root canal orifice. Since the palatal surface is functional, a butt joint should be formed between the incisal internal wall and the lingual surface of the tooth to allow for the bulk of restoration.

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Fig. 13.35  A mind-map to remember steps of access preparation

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Figs 13.36A to E  Access cavity preparation for maxillary anterior teeth. (A) Maxillary anterior tooth in which access is to be made; (B) Initial entry made through the lingual surface with the round bur perpendicular to the long axis of tooth; (C) After penetration of enamel the bur held along the long axis of the tooth till the pulp chamber is reached; (D) Complete removal of the roof of pulp chamber using round bur working from inside to outside in withdrawal movement; (E) Removal of lingual shoulder using Gates Glidden

Fig. 13.37  Access cavity outline form of maxillary central incisor (Palatal surface), (D, Distal; M, Mesial)

• Stepwise procedure: Step 1: Initial entry is through the center of lingual surface of crown using a #2 or #4 round bur to penetrate through enamel and slightly into dentin (approx. 1 mm) at an angle perpendicular to the lingual surface Step 2: Penetration of pulp chamber roof: With same round or tapered fissure bur, angle of bur is changed from perpendicular to the lingual surface to parallel to the long axis of the root until the roof of pulp chamber is penetrated.   A “drop-in” effect is felt when this occurs. Step 3: Complete roof removal: Overhanging enamel and dentin of lingual roof of pulp chamber, including pulp horns are removed by working from inside to

outside in withdrawal movement following internal anatomy using a round bur.   In case of pulpal hemorrhage that impairs visibility, coronal pulp should be amputated at orifice level with an Endodontic spoon or round bur and the chamber is filled with a viscous chelator EDTA followed by copious irrigation with sodium hypochlorite. Step 4: Axial wall extension: A tapered fissure or safe-ended bur is used in withdrawal movement to extend the access preparation for convenience form precisely in labiolingual and mesiodistal dimensions and to achieve straight-line access to the apex. Complete roof removal is confirmed using an Endodontic explorer. No “catches” or obstruction should be encountered as explorer tip is withdrawn from the pulp chamber along mesial, distal and facial walls. Step 5: Identification of all canal orifices: After deroofing the pulp chamber, locate the canal orifices using an Endodontic explorer.   Keep in mind the probability of finding additional canals in the tooth and the most likely anatomic location of these canals. Step 6 and 7: Lingual shoulder removal and orifice and coronal flaring: Lingual shoulder is lingual shelf of dentin that extends from cingulum to a point about 2 mm apical to the orifice. Its removal aids in straightline access to the apex. It is removed using tapered safety tip diamond or carbide bur or with Gates Glidden burs. During rotation, the GG bur is leaned against lingual shoulder and withdrawn.

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  The orifice should be flared using small to large GG burs. These burs are used in circumference filling motion, flaring each wall of canal in sequence. Step 8: D etermination of straight-line access: Insert into the canal the largest file that fits passively to the apical foramen or the point of 1st canal curvature to evaluate the straight-line access.   The file is inserted gently and withdrawn. If the file binds or deflects, the adequacy of lingual shoulder removal is re-evaluated. Step 9 and 10: Refinement and smoothing of restorative margins and careful evaluation of access preparation   The cavosurface margins should be refined and smoothened in order to place and finish the final restoration with precision that is necessary to minimize coronal leakage.   Using appropriate magnification devices, the completed access preparation is evaluated. It should be smooth, funnel-shaped and continuous with the radicular portion of pulp cavity. Also it must provide straight-line access to the apical third of root canal. • Variations: The access cavity preparation is designed to be more oval shaped in outline in mature teeth due to receded pulp horns. • Possible errors: – Too far gingival extension of access preparation – Failure to remove the lingual shoulder – Gouging due to improper alignment of bur – Perforations – Inadequate incisal extension causing failure to remove the tissue from the pulp horns that causes discoloration of the tooth after treatment.

Fig. 13.38  Access cavity outline form of maxillary lateral incisor (palatal surface), (D, Distal; M, Mesial)

Maxillary Lateral Incisor • External access outline form – Rounded triangle as shown in Figure 13.38. – Sometimes it is oval shaped when mesial and distal pulp horns are not prominent. – Shape of a slender triangle when the pulp horns are prominent. • Stepwise procedure: Same as for the maxillary central incisor. • Variations: Crown can have lot of variations or anatomic anomalies such as gemination, fusion with a supernumerary tooth, dens invaginatus, etc. • Possible errors: – Failure to remove lingual shoulder – Gouging due to improper inclination of bur – Perforations • Important considerations: – An important anatomic feature of this tooth that should be considered is that most of the times, the root typically curves to the distal although sometimes it may be straight. – This tooth is known to have many anomalies that may cause difficulty in treatment.

Maxillary Canine • External access outline form: Oval or slot shaped due to absence of mesial and distal pulp horns. Figure 13.39 shows the external access outline form of a maxillary canine. • Stepwise procedure: Technique is same for the maxillary central and lateral incisors. Since this tooth is heavily involved in excursive movements and occlusal function,

Fig. 13.39  Access cavity outline form of maxillary canine (palatal surface), (D, Distal; M, Mesial)

Endodontic Access Cavity Preparation

a butt joint relation is required between the incisal wall and the lingual surface of the crown for adequate thickness of restorative material. • Variations: Usually has single canal but in some cases two canals have been reported. • Possible errors: – Gouging due to improper inclination of bur – Failure to remove the lingual shoulder – Perforations.

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Maxillary Premolar Teeth Steps of Endodontic access cavity preparation for maxillary premolar teeth are shown in Figures 13.40A to F.

Maxillary First Premolar • External access outline form: Oval or slot shaped that runs in buccolingual direction with buccal extension

A

B

C

D

E

F

Figs 13.40A to F  Access cavity preparation for maxillary premolar teeth. Endodontic preparation in maxillary premolar. (A) Initial entry made parallel to the long axis of tooth through occlusal surface in the central groove of maxillary premolar using a round or small tapered fissure bur in an accelerated speed contra-angle handpiece; (B) No. 2 or No. 4 round bur is used to penetrate into the pulp chamber; (C) An Endodontic explorer used to locate the canal orifices; (D) Deroofing the pulp chamber using round bur working from inside the pulp chamber to outside; (E) Buccolingual extension and finishing of cavity walls using tapered fissure bur; (F) Final preparation should allow straight-line access of Endodontic instrument to the apex

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Figs 13.41A and B  Access cavity outline form of maxillary first premolar (occlusal view) with three and two canals respectively. (B, Buccal; D, Distal; M, Mesial; L, Lingual)

about two-third up the buccal cusp incline and palatal extension about half up the palatal cusp incline as shown in Figures 13.41A and B. • Stepwise procedure: Step 1: Removal of caries and old restorations and establishing initial outline form: Caries and restorations should be removed to achieve initial outline form. For an intact tooth, an access starting location is on the central groove between the cusp tips. Initial entry is made using a #2 round carbide bur to penetrate the enamel in the center of the occlusal surface between the buccal and lingual cusps. Step 2: Penetration of pulp chamber roof: Using the same #2 round carbide bur or tapered fissure bur, held along the long axis of tooth, penetrate through the dentin into pulp chamber.   A “drop” into the chamber is felt when the chamber is large.   Avoid underextended, shallow access opening that will expose only the pulp horn tips, mistaken for root canal orificies. Step 3: Complete roof removal: A round bur, a tapered fissure bur or a safety tip diamond or carbide bur is used to remove the roof of pulp chamber completely, including all pulp horns. Step 4: Axial wall extension: Walls of access cavity are made smooth and sloped slightly towards occlusal surface using a tapered fissure bur or a safe-ended bur. Step 5: Identification of root canal orifices: Dentinal map (anatomic dark lines on pulpal floor) should be examined to identify the orifices. Usually the orifice of buccal canal lies beneath the buccal cusp and orifice of palatal canal lies beneath the palatal cusp. Internally the access cavity should have all orifices positioned entirely on pulpal floor and should not extend in to axial wall otherwise there will be a

mouse-hole effect, which indicates under-extension that will impede straight line access. In such cases, access preparation must be further extended such that the orifices are repositioned on to pulpal floor without interference from axial walls. Step 6 and 7: Removal of cervical dentin bulges and orifice and coronal flaring: Cervical bulges are shelves of dentin that frequently overhang orifices restricting straight line access. These bulges can be removed with safety tip diamond or carbide burs or Gates Glidden burs. These instruments are gently leaned towards the dentin bulge to remove the overhanging shelf. The orifice and constricted coronal portions of the canal can be then flared with GG burs used in sweeping upward motion with lateral pressure away from the furcation in the direction of the name of the canal Step 8: Determination of straight-line access: An exploring file such as #10 K-file is inserted in the canal. It must have unimpeded access to the apical foramen or to the first point of canal curvature for proper cleaning and shaping. Step 9 and 10: Careful evaluation of access preparation and refinement and smoothing of restorative margins: This is done to reduce the potential for coronal leakage. • Variations: Sometimes three canals may be present two on the buccal side and one palatal. The third canal is the mesiobuccal canal. • Possible errors: – Perforation due to misalignment of bur at the mesiocervical indentation. – Vertical underextension exposing only the pulp horns. • Important considerations: Mesial concavity is present in the root so the preparation should not be overextended in that direction as it can result in strip perforation.

Maxillary Second Premolar • External access outline form: Oval shape with wider buccolingual extension when one or two canals are present and triangular when three canals are present. Figure 13.42 shows the access outline form of maxillary second premolar with single canal (occlusal view). • Stepwise procedure: The technique is similar to maxillary first premolar. Most of the times a single canal is present and the buccolingual extension of the access preparation is less simply corresponding to the buccal and palatal pulp horns.

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widely spaced and are nearly parallel to each other. There is slightly greater buccolingual extension to permit the straight-line access to both the canals.

Fig. 13.42  Access cavity outline form of maxillary second premolar with single canal (occlusal view), (B, Buccal; D, Distal; M, Mesial; L, Lingual)

When two canals are present, the access preparation is identical to maxillary first premolar with the difference that only single root is present and the canals are not

A

D

• Possible errors: – Perforation due to misalignment of bur at the mesiocervical indentation – Vertical underextension exposing only the pulp horns – Gouging resulting as a result of search for orifices in case of receded pulp chamber. • Important considerations: This tooth has close proximity to the maxillary sinus. Large periradicular abscess related to this tooth may drain into the sinus.

Maxillary Molar Teeth Steps of Endodontic access cavity preparation of maxillary molar teeth are shown in Figures 13.43A to G.

B

E

C

F

G

Figs 13.43A to G  Access cavity preparation for maxillary molars. (A) Buccal view of maxillary molar in which access cavity is to be prepared; (B) Proximal view of same tooth; (C) Initial entry through occlusal surface using round bur in the exact center of mesial pit; (D) Endodontic explorer is used to locate the canal orifices; (E) Deroofing the pulp chamber using round bur in withdrawal movements from inside of pulp chamber to outside; (F) Final finishing and funnelling of cavity walls; (G) Final preparation should allow unobstructed access to all the orifices

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Figs 13.44A to C  Access cavity outline form of maxillary first molar with three, four and five canals respectively (occlusal view), (B, Buccal; D, Distal; M, Mesial; L, Lingual)

Maxillary First Molar • External access outline form: When three canals are present, it is triangular with round corners as shown in Figure 13.44A. Extensions are towards mesiobuccal cusp tip, marginal ridge and oblique ridge. When four canals are present, it is rhomboidal with mesiobuccal angle forming an acute angle and distobuccal angle forming an obtuse angle, palatal angles being right angles as shown in Figure 13.44B. Mesially the access cavity does not extend into the mesial marginal ridge. Distally it should not encroach onto the oblique ridge. Buccally it should be parallel to the line connecting MB1 and DB canal orifices. Location of orifices: The main mesiobuccal canal orifice (MB 1) is located within the acute angle of the pulp chamber lying mesial and buccal to the distobuccal orifice. The distobuccal canal orifice (DB) is located within the obtuse angle of the pulp chamber. The palatal canal orifice is centered palatally. A line drawn connecting these orifices forms a triangle called as molar triangle. The fourth canal which is almost always present but commonly missed due to a ledge of dentin covering its orifice, is the second mesiobuccal canal (MB2). Its location varies: – It may lie mesial to the main MB1 canal orifice – It may be present mesial to the main MB1 canal orifice on a line joining the MB1 and palatal canal orifices. • Stepwise procedure: Step 1: Removal of caries and old restorations and establishing initial outline form: Remove caries and restorations to achieve initial outline form.   Initial entry is made using a #4 round carbide bur to penetrate the enamel with the bur held in the central fossa.

  Mesial and distal boundary limitations should be determined for access preparation. Mesial boundary is a line connecting the mesial cusp tips and the distal boundary is the oblique ridge. Step 2: Penetration of pulp chamber roof: Using the same bur, the angle of penetration is changed from perpendicular to occlusal table towards the largest canal (palatal) because the pulp chamber space usually is largest just occlusal to the orifice of this canal.   A “drop” effect will be felt. Step 3: Complete roof removal: Complete removal of roof of pulp chamber including all pulp horns using a round bur, a tapered fissure bur, or a safety tip diamond or carbide bur. Step 4: Axial wall extension: Tapered fissure carbide or diamond bur with rounded end or safe-ended diamond or carbide burs are used to funnel the corners of the access cavity directly into the orifices and to plane the axial walls and slightly flare them towards the occlusal to remove all the obstructions in the smooth, straight-line access to the canals. Step 5: Identification of all canal orifices: The anatomic dark lines in the pulpal floor (Dentinal map) should be examined with an Endodontic explorer to identify the orifices.   One should routinely search for a fourth orifice and canal that may be present in the mesiobuccal root (MB2). Step 6 and 7: Removal of cervical dentin bulge and orifice and coronal flaring: Cervical dentin bulges are shelves of dentin that may overhang the orifices restricting the straight-line access to apex and causing accentuation of existing canal curvatures. They are removed with safety tip diamond or carbide burs or Gates Glidden burs.   Orifice and the constricted coronal portion of the canal can be flared with Gates Glidden burs, used in sweeping upward motion with lateral pressure away from furcation in the direction of the name of the canal.   Sometimes an internal triangle of dentin may hinder the straight-line access of the Endodontic instrument to the apical portion of the canal. Gates Glidden burs are used to remove these internal triangles. Step 8: Determination of straight–line access: Step 9 and 10: Evaluation of access preparation and refinement and smoothing of restorative margins: • Variations: Mild to severe curvatures are seen in the roots especially the mesiobuccal root. Two or three canals in any root are possible especially in the mesiobuccal root.

Endodontic Access Cavity Preparation



  Figures 13.45A and B show clinical photo­ graphs of access cavity preparation of maxillary first molar with four canals in two cases. • Possible errors: – Underextended preparation merely exposing the pulp horns mistaken for root canal orifices. – Gouging in an attempt to search for orifices in a tooth with receded pulp chamber. – Furcal perforation due to failure to recognize the depth of pulp chamber. – Lateral perforation due to improper bur angulation. – Failure to recognize the canal curvatures causing further procedural errors such as ledging, perforation.

Maxillary Second Molar • External access outline form: When two canals are present, it is oval shaped extending buccolingually. When three canals are present, it is rounded triangle which is more obtuse due to position of distobuccal orifice being quite closer to a line connecting the mesiobuccal and palatal orifices as shown in Figure 13.46. When four canals are present, it is rhomboid shaped. • Stepwise procedure: Similar to maxillary first molar with some differences such as all orifices are located more closer mesially than in first molar.

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• Variations: Additional root canals such as second palatal canal or second canal in mesiobuccal root have been reported. – Possible errors: - Under extended preparation merely exposing the pulp horns mistaken for root canal orifices. - Gouging in an attempt to search for orifices in a tooth with receded pulp chamber. - Furcal perforation due to failure to recognize the depth of pulp chamber. - Lateral perforation due to improper bur angulation. - Failure to recognize the canal curvatures causing further procedural errors such as ledging, perforation.

Maxillary Third Molar Root canal anatomy of this tooth is unpredictable and lot of variations are possible. Access cavity preparation will vary as per the number of roots and root canals and other anatomic variations. About one to four roots and one to six canals are possible. Most of the times the roots are fused to form a single large root. Figure 13.47 shows the access cavity preparation in maxillary third molar with three canals.

Mandibular Anterior Teeth Steps of Endodontic access cavity preparation of mandibular anterior teeth are shown in Figures 13.48A to E, Figures 13.48F and G show errors in access preparation of mandibular anterior teeth. Figure 13.48H shows correct external access preparation.

Mandibular Central Incisor A

B

Figs 13.45A and B  Clinical photographs of access cavity preparation of maxillary first molar with four canals. Case A (Courtesy of Dr Roheet Khatavkar), Case B (Courtesy of Dr Shivani Bhatt)

Fig. 13.46  Access cavity outline form of maxillary second molar with three, two and one canal respectively (occlusal view), (B, Buccal; D, Distal; M, Mesial; L, Lingual)

• External access outline form: Triangular or oval shaped, which is longer incisogingivally and narrower mesiodistally as shown in Figure 13.49.

Fig. 13.47  Access cavity preparation of maxillary third molar with three canals, (B, Buccal; D, Distal; M, Mesial; L, Lingual)

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A

E

B

C

F

D

G

H

Figs 13.48A to H  Access cavity preparation for mandibular anterior teeth (A) Initial entry made through lingual surface in the exact center using a tapered fissure bur in accelerated speed contra-angle handpiece perpendicular to long axis of tooth; (B) Round bur No. 2 to penetrate into pulp chamber; (C) Round bur used to deroof the pulp chamber working from inside the pulp chamber to outside; (D) Removal of lingual shoulder and finishing the cavity walls; (E) Final preparation should allow unobstructed straight-line access of Endodontic instrument to the apex; (F) Inadequate access opening can let the pulp tissue remnants to remain the coronal part of the tooth leading to discoloration later; (G) Failure to remove the lingual shoulder will lead to missed lingual canal causing Endodontic failure; (H) Correct extension after removal of lingual shoulder causing straight-line access of Endodontic instrument in both the canals

• Stepwise procedure: Technique is similar to that of maxillary central incisor. The initial entry point is just above the cingulum with the bur held perpendicular to the entry point. Remove the lingual shoulder completely as this tooth often has two canals that are buccolingually oriented and the lingual canal most often gets missed. About



40% of mandibular incisors have two canals—buccal and lingual. It is not necessary to have butt joint junctions between the internal walls and the lingual surface because lingual surface of the tooth is not involved in occlusal function.

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A

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B

Figs 13.49A and B  Access cavity outline form of mandibular central incisor with one canal and mandibular lateral incisor with two canals, (D, Distal; M, Mesial)

Fig. 13.50  Access cavity outline form of mandibular canine (incisal view) with one and two canals, (B, Buccal; D, Distal; M, Mesial; L, Lingual)

• Possible errors: – Extension too far gingivally. – Failure to remove the lingual shoulder that mostly causes missed lingual canal. – Gouging due to improper bur angulation and failure to recognize the linguoaxial or mesioaxial angulation of tooth. – Inadequate incisal extension causing failure to completely remove the pulp debris causing discoloration of tooth after treatment as shown in Figure 13.48F.

larger and its cusp tip is inclined lingually, so the access preparation lies more to the mesial of the midpoint mesiodistally. Figure 13.50 shows the access outline form of mandibular canine (incisal view). • Stepwise procedure: Technique is similar to Maxillary canine. The lingual shoulder must be removed to gain access to the lingual wall of the root canal or to the entrance of a second canal. Buccal wall is larger and the lingual wall is slit-like. As a result, cleaning and shaping may be difficult. Like the mandibular incisors, butt joint junctions are not necessary. • Possible errors: – Extension too far gingivally – Failure to remove the lingual shoulder that mostly causes missed lingual canal – Gouging due to improper bur angulation and failure to recognize the linguoaxial or mesioaxial angulation of tooth. – Inadequate incisal extension causing failure to completely remove the pulp debris causing discoloration of tooth after treatment.

Mandibular Lateral Incisor • External access outline form: Triangular or oval shaped which is longer incisogingivally and narrower mesiodistally. Figure 13.49B shows the access outline form of mandi­bular lateral incisor with two canals from incisal view. • Stepwise procedure: Same as mandibular central incisor • Possible errors: – Extension too far gingivally. – Failure to remove the lingual shoulder that mostly causes missed lingual canal. – Gouging due to improper bur angulation and failure to recognize the linguoaxial or mesioaxial angulation of tooth. – Inadequate incisal extension causing failure to comple­t ely remove the pulp debris causing discoloration of tooth after treatment.

Mandibular Canine • External access outline form: Oval or slot-shaped narrow mesiodistally and wider buccolingually. Its incisal extension is towards the incisal edge and gingival extension penetrates the cingulum. Mandibular canine has almost straight mesial edge, its distal surface is

Mandibular Premolar Teeth Steps of Endodontic access cavity preparation of mandibular premolar teeth are shown in Figures 13.51A to E.

Mandibular First Premolar • External access outline form: Oval shaped as shown in Figure 13.52. • Stepwise procedure: The procedure is the same as for the maxillary premolars. But some specific points for mandibular first premolar are: – Usually the initial entry is made at the upper third of lingual incline of the facial cusp with #2 round

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B

C

D

E

Figs 13.51A to E  Access cavity preparation of mandibular premolars: (A) Initial entry through occlusal surface in the central groove of mandibular premolar; (B) Round bur used to penetrate into the pulp chamber; (C) Endodontic explorer used to locate canal orifice; (D) After deroofing of pulp chamber, tapered fissure bur used for buccolingual extension and finishing of cavity walls; (E) Final preparation should allow straight line access of Endodontic instrument to the apex

Fig. 13.52  Access cavity outline form of mandibular first premolar with one and two canals respectively (occlusal view), (B, Buccal; D, Distal; M, Mesial; L, Lingual)

carbide bur centered mesiodistally and directed along the long axis of root. This helps to compensate for the tilt and to prevent perforations. – When two canals are present, they tend to be round from the pulp chamber to their foramen. Sometimes a single broad root canal may bifurcate into two separate root canals. – Direct access to buccal canal usually is possible, whereas lingual canal may be very difficult to find due to following reasons: The lingual canal tends to diverge from the main canal at a sharp angle and the crown has lingual inclination that directs files buccally, making location of lingual canal orifice more difficult. To counter this, lingual wall of the access cavity needs to be extended farther lingually, this makes lingual canal easier to locate.

– Because of lingual inclination of the crown, buccal extension can nearly approach the tip of buccal cusp to achieve straight-line access. – Mesiodistally the access preparation is centered between the cusp tips. • Possible errors: Perforation due to improper bur angulation or due to failure to recognize the lingual inclination of the crown – Inadequate extension causing further preparation errors – Apical perforation due to overinstrumentation or due to failure to recognize the buccal or lingual apical curvature. • Important considerations: Due to lingual inclination of the crown, the access cavity needs to be extended lingually so that the lingual canal is easier to locate and negotiate. Also the buccal extension should be approaching the buccal cusp tip to achieve straight-line access.

Mandibular Second Premolar • External access outline form: Oval shaped as shown in Figure 13.53. • Stepwise procedure: Similar to mandibular first premolar, with few specific variations: – Crown has less lingual inclination, so less extension up the buccal cusp incline is required for straight-line access.

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• Possible errors: – Perforation due to improper bur angulation or due to failure to recognize the tilt of premolar – Inadequate extension causing further preparation errors – Apical perforation due to overinstrumentation or due to failure to recognize the buccal or lingual apical curvature. Fig. 13.53  Access cavity outline form of mandibular second premolar (occlusal view), (B, Buccal; D, Distal; M, Mesial; L, Lingual)

– Lingual half of the tooth is more fully developed, so lingually access preparation may extend halfway up the lingual cusp incline.

A

E

B

Mandibular Molar Teeth Steps of Endodontic access cavity preparation of mandibular molar teeth are shown in Figures 13.54A to G.

C

F

D

G

Figs 13.54A to G  Access cavity preparation of mandibular molars. (A) Buccal view of mandibular molar in which access is to be prepared; (B) Proximal view of same tooth; (C) Initial entry made using round bur through the occlusal surface in the exact center of the mesial pit; (D) Endodontic explorer is used to locate the canal orifices; (E) Round bur is used from inside to outside of the pulp chamber for deroofing of the pulp chamber; (F) Final finishing and funnelling of access cavity walls; (G) Final access preparation should allow unobstructed access to the canal orifices

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Fig. 13.55  Access cavity outline form of mandibular first molar with three, four and five canals respectively (occlusal view). (B, Buccal; D, Distal; M, Mesial; L, Lingual)

Mandibular First Molar • External access outline form: Trapezoid or triangular shaped with rounded corners and rectangular if two distal canals are present. Figure 13.55 shows the external access outline form of mandibular first molar with three, four and five canals respectively (occlusal view). Mesially the access preparation should not invade the marginal ridge. Distally it should be extended so as to have adequate access to the distal canals. Buccal and lingual wall are formed by the lines connecting the respective two orifices • Stepwise procedure: Step 1: Removal of caries and old restorations and establishing initial outline form: Remove caries and restoration to achieve initial outline form. Initial entry is made using #4 round carbide bur to penetrate the enamel in the central fossa perpendicularly. The starting location for molar access cavity preparation is determined by establishing mesial and distal boundary limits. Step 2: Penetration of pulp chamber roof: Using the same bur, angle of penetration is changed from perpendicular to occlusal table towards the largest canal (distal) because the pulp chamber space usually is largest just occlusal to the orifice of this canal. A “drop” effect will be felt. Step 3: Complete roof removal: Complete roof removal including the pulp horns using a round bur, tapered fissure bur, or a safety tip diamond or carbide bur. Step 4: Axial wall extension: Tapered fissure carbide or diamond bur with rounded end or safe-ended diamond or carbide burs are used to funnel the corners of the access cavity directly into the orifices and to plane the axial walls and slightly flare them towards the occlusal to remove all the obstructions in the smooth, straight line access to the canals. Step 5: Identification of all canal orifices: The anatomic dark lines in the pulpal floor (Dentinal map) should be

examined with an Endodontic explorer to identify the orifices. Usually all canal orifices are located in the mesial two-thirds of crown. Mesial canal orifices are connected by developmental groove and are well-separated within pulp chamber. Mesiobuccal orifice is under the mesiobuccal cusp. Sometimes the mesiobuccal cusp tip has to be encroached on to achieve straight-line access. Mesiolingual orifice is found just lingual to the central groove. In case of single distal canal, the orifice is oval buccolingually and the opening generally is located distal to the buccal groove that can be explored from mesial side. Step 6 and 7: Removal of cervical dentin bulge and orifice and coronal flaring and removal of internal triangles of dentin. Step 8: Determination of straight-line access. Step 9 and 10: Final evaluation of access preparation and refinement and smoothing of restorative margins. Figure 13.56 shows the clinical photograph of completed access cavity preparation in mandibular molar seen under magnification. • Variations: In between mesiobuccal and mesiolingual canals, a middle mesial canal may be present as seen in Figure 13.57. • Possible errors: – Gouging in an attempt to search for orifices in a tooth with receded pulp chamber – Furcal perforation due to failure to recognize the depth of pulp chamber – Lateral perforation due to improper bur angulation – Missed second distal canal – Ledge formation due to underextended access preparation – Failure to recognize the curvature in the canal causing further procedural errors such as ledging or perforation. • Important considerations: The mesial and the lingual inclination of the crown should be considered during access preparation on this tooth to prevent unnecessary gouging.   A concavity is present on distal surface of mesial root and on mesial surface of distal root. So careful instrumentation should be done to avoid strip perforation.

Mandibular Second Molar • External access outline form: When three canals are present, triangular form or slightly rhomboid shaped.

Endodontic Access Cavity Preparation

Fig. 13.56  Clinical photograph of access cavity preparation in mandibular molar with four canals seen under microscope (Courtesy of Dr Roheet Khatavkar)

When two canals are present, rectangular shaped opening which is wider mesiodistally. When only one canal is present, oval shaped in the center of occlusal surface. • Stepwise procedure: Similar to mandibular first molar with the variations due to smaller size. Due to buccoaxial inclination of the tooth, sometimes large portion of mesiobuccal cusp may have to be reduced to clean and shape the mesiobuccal canal. The two mesial orifices are located closer together. • Variations: Mandibular second molars have roots and canals usually close together and may have single or fused roots. One to six canals are possible. Sometimes a file placed in mesiobuccal canal may appear to be in the distal canal when these two canals are connected by a semicircular slit in case of a C-shaped canal (Fig. 13.58). Figures 13.59A to D show the outline form of mandibular second molar with 3, 4, 2 canals respectively and C-shaped canal (occlusal view). C-shaped canals have been described in detail in Chapter 3: Morphology and Internal Anatomy of the Root Canal System. • Possible errors: – Gouging in an attempt to search for orifices in a tooth with receded pulp chamber – Furcal perforation due to failure to recognize the depth of pulp chamber – Lateral perforation due to improper bur angulation – Missed second distal canal

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Fig. 13.57  Clinical photograph of access opening in mandibular first molar with three canals (Additional middle mesial canal) (Courtesy of Dr Shivani Bhatt)

Fig. 13.58  Clinical photograph of access opening done in mandibular second molar with C-shaped canal (Courtesy of Dr Roheet Khatavkar)

– Ledge formation due to underextended access preparation – Failure to recognize the curvature in the canal causing further procedural errors such as ledging or perforation • Important considerations: Distal aspect of mesial root and mesial aspect of distal root have concavities. So careful instrumentation should be done to avoid strip perforation. The roots have close proximity to the mandibular canal. So appropriate working

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A

B

C

D

Figs 13.59A to D  Mandibular second molar with (A) 3 canals; (B) 4  canals; (C) 2 canals; (D) C-shaped canal, (B, Buccal; D, Distal; M, Mesial; L, Lingual)

length determination should be done to avoid overinstrumentation.

Mandibular Third Molar It may have unpredictable anatomy. Lot of variations are possible. May have severely curved roots. Access preparation varies according to the number of roots and root canals and other anatomic variations. Figure 13.60 shows the access cavity preparation in a mandibular third molar tooth with three canals.

WHICH ARE THE CHALLENGING ACCESS CAVITY PREPARATIONS AND HOW TO DEAL WITH THEM? Teeth with Calcifications in Pulp Chamber and Root Canals • Challenge: Identification of calcified root canal orifices and then negotiation of calcified canals is a challenge. • Possible errors: – Improper attempt to locate canals can lead to perforations of root wall or of the furcation. – Overzealous attempt to locate canals can cause excavation of large amount of sound dentin resulting in weakening of tooth structure (Figs 13.61A to C)

Fig. 13.60  Access cavity preparation in mandibular third molar with three canals, (B, Buccal; D, Distal; M, Mesial; L, Lingual)

• Safe approach to face the challenge: – Knowing beforehand that calcification exists, to be prepared to deal with it, is important. Careful reading of preoperative radiograph will reveal calcification of pulp chamber and radicular canal spaces. – One must know that calcification progresses from the coronal part to the apex of the root. There may be severe coronal calcifications but the canals become less calcified as they approach the apex. So, complete cleaning, shaping and obturation of these canals upto the apical terminus needs to be achieved. – Use of adequate illumination (For example, transillumination with fiber-optic light) and magnification (For example, dental operating microscope or loupes) is very helpful diagnostic aids in such cases. – Careful examination of color differences can help in searching the calcified orifices. Floor of pulp chamber is darker in color than the walls of the pulp chamber. Developmental grooves connecting orifices are lighter in color than the floor of pulp chamber. – Exact knowledge of the anatomic location of root canal orifices and possible variations and knowing the fact that canal orifices are located at the end points of developmental grooves and at the angles formed by the pulp chamber walls and floor. – Other diagnostic aids for location of calcified root canal orifices: - Use of sharp Endodontic explorer - Use of ultrasonic tips - Sodium hypochlorite champagne bubble test - Sequential application of 17% EDTA and 95% ethanol – Patency of the canal can be determined using smaller Endodontic files such as #6, #8 K-files coated with chelating agent such as EDTA

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A

B

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C

Figs 13.61A to C  (A) Radiograph showing calcified canal in maxillary left central incisor tooth, in which overzealous attempt to locate canal has removed large amount of sound dentin; (B) With the use of dental operating microscope (DOM) and adequate light, the root canal was located and negotiated, cleaned and shaped and obturation completed; (C) Access cavity opening sealed with a restoration (Courtesy of Dr Roheet Khatavkar)

– Patience and slow, careful removal of dentin is the key for uncovering calcified canals.

Teeth with Curved Canals • Challenge: Following the anatomic curvature and its complete cleaning, shaping and obturation is the challenge. • Possible errors: – Failure to follow the curvature, can result in procedural errors such as: - Ledge formation - Apical transportation and zipping - Root perforations - Incomplete cleaning and shaping • Safe approach to face the challenge: – Recognition of canal curvature from preoperative radiographs. Figure 13.62 shows postoperative radiographs of two cases of maxillary first premolar with curved/Sshaped/Bayonet shaped canals. – Sometimes the root may not seem to be curved on radiograph, but there may be sharp angle between the pulp chamber and the canal, which should be carefully evaluated from radiographs. In such cases, to obtain SLA, significant reduction of orifice walls may be required. – Precurving the Endodontic files – Adequate extension of access cavity preparation to allow for straight-line access (SLA) to curved canals – Careful use of rotary files in curved canals.

Fig. 13.62  Postoperative radiographs of two cases of maxillary first premolar with S-shaped/Bayonet-shaped canals (Courtesy of Dr Roheet Khatavkar)

Teeth with Unusual and Complex Anatomy of Roots and Root Canals • Challenge: Complete cleaning and shaping and obturation of such complex root canal system is a challenge. • Possible errors: Failure to negotiate through such complex root canals can cause – Inadequate cleaning and shaping – Inadequate or ineffective obturation

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• Safe approach to face the challenge: – Careful reading of preoperative radiographs to recognize such complexities – Careful negotiation and instrumentation of such root canals keeping in mind the complex anatomy.

Teeth with Minimal Coronal Tooth Structure • Challenge: To conserve as much sound tooth structure as possible to protect it from fracture. – Crown to root relation may not be identified due to inadequate coronal tooth structure. • Possible errors: Coronal or root perforation may occur as a result of loss of significant coronal anatomy. • Safe approach to face the challenge: – Careful study of preoperative radiographs to study the root angulation – Careful probing of the cervical crown anatomy with an explorer – Palpate the root eminences – Start access before placing rubber dam in such cases – If the canal is not located till a greater depth, then instead of attempting to search the orifices, take radiographs at various angles before proceeding.

Crowded Teeth • Challenge: To obtain straight-line access while conservation of tooth structure and without compro­ mising esthetics is the challenge. • Possible errors: – Inadequate access leading to inadequate cleaning and shaping, missed canals, etc. – Failure to achieve straight-line access (SLA) causing further procedural errors • Safe approach to face the challenge: – Such cases may require an alternative approach of access preparation – Sometimes buccal access preparation will have to be made to achieve SLA.

Rotated Teeth • Challenge: To visualize the anatomic crown-to-root relationship before making access preparation in order to correctly angulate the bur with respect to the long axis of root is the challenge. • Possible errors: – Perforations during access preparation – Missed canals

– Excessive gouging of coronal or radicular tooth structure in search of orifice of canal in a wrong direction. • Safe approach to face the challenge: – Determine the anatomic relationship of the crown to root by taking angled diagnostic periapical radiographs – Visualize and determine if there are any likely variations that have to be made during access cavity preparation.

Access Through Full Veneer Crowns • Challenge: If the full veneer crown has to be retained, making access cavity preparation through it is a challenge. • Possible errors: – If you are conservative during access cavity preparation, preparation may be underextended causing various procedural errors. – Failure to recognize crown to root angulation may result in perforation. – Leakage or recurrent caries may be left unattended to resulting in failures later. • Safe approach to face the challenge: – When you prepare access through the full veneer crown, do it with caution. – Check the root prominence. – Identify the long axis of the tooth. – Carefully evaluate preoperative radiographs to find if the full veneer crown has been altered. For example, rotated tooth may have the full veneer crown that is in the correct position and not in rotated position. – Also, evaluate from preoperative radiograph, the mesial/distal or axial inclination of the involved tooth and its parallelism to the adjacent teeth. – Check for the orientation of adjacent teeth clinically. – Dental operating microscope (D OM) and transillumination of CEJ can be a valuable aid. – When some doubt exists that the underlying tooth may be rotated, drill through the center of the full veneer crown for a safe access. Table 13.1 shows the summary of the challenging access preparations.

WHAT ERRORS CAN OCCUR DURING ACCESS CAVITY PREPARATION? Errors may occur in access cavity preparation if: • There is clinician’s lack of understanding of the internal or external morphology of tooth or

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TABLE 13.1  Summary of the challenging access preparations Challenging access preparations

Possible errors

Safety measures

• Teeth with calcifications in pulp chamber and root canals

• Perforations • Weakening of tooth structure

• Preoperative recognition of calcification from radiographs • Knowledge about progress of calcification • Adequate illumination and magnification • Evaluating color differences • Knowledge of anatomic location of root canal orifices • Diagnostic aids to locate orifices • Smaller Endodontic files • Chelating agent • Patience and caution

• Teeth with curved canals

• Ledge formation • Apical transportation and zipping • Root perforations • Incomplete cleaning and shaping

• Recognition • Optimal reduction of orifice walls for SLA • Precurving of files • Use more flexible files • Careful use of rotary files

• Teeth with unusual complex anatomy of roots and canals

• Inadequate cleaning and shaping • Ineffective obturation

• Recognition • Careful negotiation and instrumentation keeping in mind the complex anatomy

• Teeth with minimal coronal tooth structure

• Perforations

• Evaluation of root angulation by palpation and using radiographs • Start access preparation before placing rubber dam • Radiographs at different angulations

• Crowded teeth

• Inadequate access • Failure to achieve SLA causing procedural errors

• Alternate approach of access preparation • Buccal access preparation may be required

• Rotated teeth

• Perforations • Missed canals • Excessive gouging of tooth structure

• Radiographs at different angulations • Variations/alterations in the usual access preparation

• Access through full veneer crowns

• Under extended preparation • Perforations unrecognized • Leakage or recurrent caries

• Caution • Careful evaluation of preoperative radiograph • DOM and transillumination • Stay in center of tooth when in doubt

Fig. 13.63  A mind-map to remember errors in access cavity preparation

• The clinician does not follow access guidelines.

Poor Access Cavity Design • Inadequate extension: Inadequate mesial or distal extension may leave the orifices uncovered. Failure to remove the pulpal roof completely is called vertical underextension. • Inadequate opening: Inadequate access opening results in inadequate instru­mentation and obturation and it can also cause various procedural problems like: – Coronal discoloration when pulp horns are not debrided. – Instrument breakage (separation) – Ledging of canal – Apical transportation. • Overextension: Gross overextension of access cavity preparation will weaken the coronal tooth structure and

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hence compromise the final restoration and longevity of the treated tooth. • Overzealous tooth removal: Gouging Improper bur angulation and failure to recognize the inclination of tooth can result in overzealous tooth removal. This results in weakening and mutilation of tooth structure predisposing it to fracture. These have been discussed in detail in Chapter 20 Endodontic Mishaps: Management and Prevention.

Perforations Results in communication between root canal system and the periodontal tissues.

(Discussed in detail in Chapter 20 Endodontic Mishaps: Management and Prevention). Figure 13.63 shows a mind-map to remember the errors in access cavity preparation.

BIBLIOGRAPHY 1. Cohen S, Hargreaves KM. Pathways of Pulp, 9th edn. St. Louis: Mosby. 2006.pp.165-228. 2. Grossman L, Oliet S, Del Rio C. Endodontic Practice, 11th edn. Varghese publication. 1991.pp.151-77, 79. 3. Ingle J, Bakland L, Baumgartner J, Ingle’s Endodontics, 6th edn. BC Decker Inc, Hamilton. 2008.pp.877-918. 4. Ingle, Bakland, Endodontics, 5th edn. Plates 3 to 27, BC DeckerElsevier. 2002.

CHAPTER

14

Cleaning and Shaping of the Root Canal System Including Working Length Determination

This chapter describes the objectives and the various concepts and strategies for effective root canal preparation and discusses in detail the root canal preparation techniques.   You must know • What is Cleaning and Shaping of Root Canals? • What are the Objectives of Cleaning and Shaping of Root Canals? • Which are the Important Numerical Concepts in Root Canal Preparation and how to Determine Them? • What are the Current Concepts and Terminology for Root Canal Preparation? • Which are the Different Instrument Motions for Effective Shaping of Root Canals? • What are the Requirements before Starting Canal Preparation? • Which are the Different Canal Preparation Techniques? • What are the Precautions to be taken during Instrumentation? • What are the Procedural Errors that can Occur during Root Canal Preparation?

WHAT IS CLEANING AND SHAPING OF ROOT CANALS?

‘Cleaning’ and ‘Shaping’ Concepts

Definition of Biomechanical Preparation

Effective ‘Shaping’ is the mechanical instrumentation of the root canal with hand and rotary instruments to remove vital and necrotic pulp tissue and eradicate microbes from the accessible parts of the root canal and to shape the canals in such a way that directs and facilitates optimal irrigation, debridement and placement of local medicaments followed by 3-dimensional obturation of the root canal system. Shaping is specific for each root. Effective ‘Cleaning’ refers to the use of chemicals to eradicate microorganisms, dissolve necrotic tissue and remove necrotic dentin and debris created from instrumentation by means of antimicrobial irrigating solutions, detergents and decalcifying materials and then placement of intracanal medicaments to render the root canal system free of microbes.

“Obtaining straight-line access to the apical foramen and enlarging and disinfecting the root canals by chemomechanical means without causing injury to the periapical tissues is called biomechanical preparation of root canals”. Earlier the term biomechanical preparation was commonly used. However, now the terms ‘radicular preparation’ and cleaning and shaping of root canals,’ are commonly used. ‘Cleaning’ and ‘Shaping’ are two interdependent steps of root canal treatment procedure performed in order to obtain complete disinfection of root canal system and to obtain a continuously tapering funnel from coronal access to apex in order to facilitate 3-dimensional obturation of root canals.

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Without irrigation, mechanical instrumentation becomes ineffective rapidly due to accumulation of debris. Without enlarging and shaping, the irrigating solutions cannot reach all parts of the root canal system. Shaping removes restrictive dentin thereby improving the effectiveness and the control of canal preparation and allows irrigation solution to completely penetrate the root canal system. Thus, shaping facilitates cleaning and cleaning facilitates shaping. Also only well-shaped canals can be filled in three dimensions. Thus, shaping facilitates 3-D obturation. Various instrumentation and shaping techniques will be discussed in this chapter. Various chemical agents used for effective cleaning will be discussed in the next chapter (Chapter 15).

WHAT ARE THE OBJECTIVES OF CLEANING AND SHAPING OF ROOT CANALS? Biologic objectives are to: • Remove pulp tissue remnants and infected dentin from the root canal system. • Remove bacteria and their endotoxins and all potential irritants from the entire canal system. • Confine all instrumentation procedures within the root canal space. • Avoid pushing contaminated debris beyond the apical foramina. • Create sufficient space within the canal for irrigation and intracanal medicaments (Remember biologic objectives-CCARR). Mechanical objectives: (Remember these mechanical objectives with the help of following sentence: Kindly Prepare Design Mechanically with Anatomy Maintained and Less Disturbed.) • Develop a smooth continuously tapering funnel-shaped preparation in all three-dimensions such that the crosssectional diameter of the canal narrows towards the foramen. • Maintain the original root canal anatomy by fully incorporating all walls of canals into prepared shape such that the preparation flows with the shape of the original canal. • Maintain the original position of apical foramen. • Keep the apical opening as small as practically possible. • Leave as much radicular dentin as possible to prevent weakening of root structure.

• Prepare a sound apical dentin matrix at the cementodentinal junction (CDJ) for apical seal. • Design the preparation such that the cross-sectional diameter becomes narrower at every point apically. • Avoid preparation errors such as zipping, perforations, etc. Clinical objectives: • To remove restrictive dentin in order to – Improve effectiveness and control of canal preparation, – Allow irrigation solution to completely penetrate the root canal system (Shaping facilitates cleaning). • To remove the accumulated debris created by mechanical instrumentation by means of root canal irrigation for effective shaping (Cleaning facilitates shaping). • To develop a logical cavity preparation specific for the anatomy. • To allow for three-dimensional filling of well-shaped and cleaned root canals (Cleaning and shaping facilitates three-dimensional obturation of the root canal system). Figure 14.1 shows the mind-map to remember all objectives of cleaning and shaping.

Fig. 14.1  Mind-map of objectives of cleaning and shaping

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WHICH ARE THE IMPORTANT NUMERICAL CONCEPTS IN ROOT CANAL PREPARATION AND HOW TO DETERMINE THEM? Endodontic treatment involves preparation of the coronal and radicular spaces (Earlier called Biomechanical preparation, now termed as Cleaning and Shaping of the root canal system). Coronal access cavity preparation has been described in detail in the previous chapter (Chapter 13 Endodontic Access Cavity Preparation). Radicular preparation or root canal preparation is discussed in detail in this chapter. The important concepts in root canal preparation are as follows:

Fig. 14.2  Significance of determining working length (WL)

Working Length Canal length is the distance from a coronal reference point to the apical exit of the root canal. Anatomic apex of the root is the tip or end of the root which is morphologically determined. Radiographic apex of the root is the tip or end of the root which is determined on the radiograph. The radiographic apex may be different from the anatomic apex due to variations in the morphology of the root and factors related to the radiographic technique.

Definition of Working Length According to Glossary of Endodontic terms: “Working length is defined as the distance from a coronal reference point to the point at which the canal preparation and obturation should terminate”.

Significance Figure 14.2 gives the importance of working length determination.

Apical Limit of Working Length • Theoretically, the apical extent for termination of root canal preparation and obturation is the cemento-dentinal

A

B

Figs 14.3A and B  Representation of how the position of apical foramen changes the working length: (a) Tooth length; (b) Working length

junction (CDJ), which is a histological entity and cannot be accurately determined clinically. • Clinically, the desired apical extent considered is the apical constriction, which does not always coincide with the CDJ. Apical constriction is located about 0.5–1 mm short of the radiographic apex. Apical constriction is the portion of the root canal with narrowest diameter, also referred to as minor apical diameter. Figures 14.3A and B show how the position of apical foramen changes the working length.

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Method for Determination of Working Length • The process of determination of the current working length (WL) is called Endometrics. • Requirements for the ideal method of accurate working length determination: Ingle 6th edition has given following requirements: – The method should allow location of apical constriction rapidly (Quick) – The method should provide accurate readings in all conditions of pulp and in the presence of all canal contents – The method should provide easy measurement – The method should allow for confirmation and periodic monitoring of working length – The method should be comfortable to both the patient and the clinician – The method should cause minimal radiation to patient – The method should be easy to use even in specific condition of patient such as severe gag reflex, limited opening of mouth and pregnancy – The method should be economical. Since no single method satisfies all requirements, combination of several methods should be used for accurate working length determination. • Various methods for working length determination: 1. Digital tactile sense 2. Evaluation of patient’s response to a file introduced into the canal (Apical periodontal sensitivity) 3. Evaluation of paper point placed in the canal 4. Use of mathematical formula (Grossman’s method) 5. Use of radiographs Different radiographic methods: a. Grossman’s method b. Ingle’s method c. Weine’s method d. Kuttler’s method e. Radiographic grid f. Endometric probe g. Direct digital radiography h. Xeroradiography i. Subtraction radiography 6. Use of electronic apex locators. Currently, the widely used method for working length determination is the combination of use of electronic apex locators and the radiographs.

Digital Tactile Sense Resistance is felt as the file approaches the apical 2–3 mm, which can be detected by tactile sense by an experienced

clinician especially when the coronal portion has been adequately enlarged. This method requires that the canal is preflared prior to determining the working length. The tactile method can be used as a supplementary method with other methods for working length determination but cannot be used alone because it has high chances of giving inaccurate measurements in case of excessively constricted and curved canals. It is also an inaccurate method in root canals with an immature apex.

Evaluation of Patient’s Response to a File Introduced in the Canal (Apical Periodontal Sensitivity) This is not a method for working length determination per se, but a file introduced beyond the apical constriction causes painful response, which gives an indication that the WL would be approximately lesser than this length to which the file was introduced. This, however, can be misleading when a file is advanced in a canal with inflamed tissue may cause pain even when instrument tip is short of apical constriction.

Evaluation of Paper Point Placed in the Canal In this method, the blunt end of the paper point is gently inserted in the canal to the extent it can penetrate after profound anesthesia. The moisture or blood on the apical portion of the paper point gives an estimation of WL. This method is also a supplementary method to aid in working length determination. It is useful in canals with immature root apex and in cases of apical resorption or perforation where the moisture or blood determines the amount of overextension.

Use of Mathematical Formula • Grossman’s formula KLI × ALT Correct Length of Tooth (CLT) = __________________ ALI Where, KLI = Known length of instrument or the pre­ measured length ALT = Approximate length of tooth from radiograph ALI = Approximate length of instrument from radiograph In this method, a premeasured file is placed in the canal and a radiograph is taken and then using the above formula, the working length is determined. Methods requiring formula for working length determination have been abandoned. Bramante and

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Fig. 14.5  Endoblock from side (Courtesy of Dentsply)

A

B

Figs 14.4A and B  Weak unsupported enamel is ground to obtain a flat, stable reference plane

Berbert found great variability in formulaic determination of working length, with only a small percentage of successful measurements.

Use of Radiographs Requirements • For determination of working length, the radiographs taken should be of good quality and undistorted. • Reference points: The anatomical landmark on tooth used as coronal reference point should be reproducible. So, the cusps which are weakened by caries or restoration may have to be reduced to a flat surface as shown in Figures 14.4A and B in order to have a stable reference plane and thus preventing the possibility of loss of reference point due to fracture of weak enamel or cusps in between appointments. • Exploring instrument: In this method, an appropriate size K-file with an instrument stop is used as exploring instrument to determine the working length. Smaller fine instruments such as #8 and #10 K-files when used as exploring instruments may be quite loose in the canals and may cause errors in WL and also their tips are sometimes not clearly visible on radiographs. So, an instrument size which is not very small but can negotiate the entire length of root canal should be used as exploring instrument such as no.15 K-file. • A scale or an Endodontic millimeter ruler such as a calibrated “Endoblock’ is used to adjust the instrument stop.

A

B

Figs 14.6A and B  Instrument stop should be placed perpendicular to the reference plane: (A) Incorrect placement of instrument stop; (B) Correct placement of instrument stop

Figure 14.5 shows the photograph of an Endoblock. • Instrument stops should be properly placed on the shaft of the exploring instrument such that it lies perpendicular to the shaft as shown in Figure 14.6B. Instrument stops made of different materials such as metal, plastic and silicone rubber are available. Teardrop-shaped silicone rubber stops help in the orientation of instrument into canal curvatures and they need to be removed from the instrument during sterilization.

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Fig. 14.7  Measurement of approximate tooth length from a preoperative radiograph

Steps Involved in this Method Step 1: From a preoperative diagnostic radiograph, the length of the tooth from the occlusal surface to the root apex is measured as shown in Figure 14.7. Then, 1 mm is deducted from this length as ‘safety allowance’ for possible radiographic distortion as shown in Figure 14.8. This is tentative working length. Step 2: An appropriate sized K-file is inserted into the root canal with a slight wiggling motion so that it can bypass any obstruction or debris and be placed till the tentative working length. Shaft of K-file should have properly placed instrument stop at the level of coronal reference points. Step 3: Take a radiograph. Step 4: Determine the difference between the end of the instrument and the end of the root. Step 5: If necessary, the measured length is adjusted such that the instrument tip lies about 0.5 mm from the radiographic apex as shown in Figures 14.9A and B. Step 6: If apical resorption is evident on radiograph, then Weine has recommended that the working length be kept about 1.5–2 mm short of the radiographic apex.

Different Radiographic Methods a. Grossman’s method: Using the mathematical formula described above.

Fig. 14.8  Deducting 1 mm and determining tentative working length

A

B

Figs 14.9A and B  Here, the measured length adjusted so that instrument tip lies about 0.5 mm from radiographic apex

b. Ingle’s method of working length determination: Makes use of a preoperative radiograph of tooth to be treated. The length of the tooth is determined from this radiograph and an instrument adjusted to 1 mm lesser

Cleaning and Shaping of the Root Canal System Including Working Length Determination

than this length is placed in the canal and a radiograph is taken to determine the working length. c. Weine’s method: It makes use of radiographs for working length determination and Weine has recommended the following apical termination points: – If no bone or root resorption—1 mm from apex – If only bone resorption—1.5 mm from apex – If both bone and root resorption—2 mm from apex d. Kuttler’s method: According to studies done by Kuttler, the root canal preparation should terminate at apical constriction, i.e. minor diameter. The average distance between the major and minor diameter: – Young patients—0.524 mm – Older patients—0.659 mm Step-wise procedure: i. Locate major and minor diameter on the preoperative radiograph. ii. Estimate length of the roots from preoperative radiograph using a millimeter scale. iii. Estimate width of root canal on the preoperative radiograph using #10 or #15 K-file for narrow canal, #20 or #25 K-file for average width and #30 or #35 K-file for wide canals. iv. Insert the selected K-file in the root canal to the estimated canal length and take a radiograph. v. On radiograph: - If file appears too long or short by more than 1 mm from the minor diameter, then readjust the instrument accordingly and take another radiograph to confirm. - If file appears reaching the major diameter, subtract 0.5 mm from that length in young patients and subtract 0.67 mm in case of older patients. vi. Advantages of this method: It is quite accurate with minimal errors and has resulted in many successful cases. vii. Disadvantages of this method: It is complicated method and requires excellent quality radio­ graphs. e. Radiographic grid: This method involves superimposing a millimeter grid on the radiograph, making it simpler to estimate the working length with no need for calculation. But if the radiograph is bent, it may not give the correct length. f. Endometric probe: This method uses the graduations on diagnostic file which are visible on the radiograph. Endometric probe is etched at millimeter increment. The disadvantage of this method is that the smallest size of file used is number 25.



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Direct digital radiography (RadioVisuo Graphy and Phosphor Imaging System), Xeroradiography and Subtraction radiography are the advanced radiographic methods for determining the working length, with digital radiography being quite common and widely used these days. These methods have been described in detail in Chapter 7 Diagnosis and Diagnostic Aids in Endodontics.

Use of Electronic Apex Locators Radiographs enable us to arbitarily work around the apical constriction. To overcome this limitation, an electronic device called apex locator was introduced that helps to accurately determine the position of apical constriction or the Cemento-Dentinal Junction (CDJ) and not the radiographic apex (The term apex locator is a misnomer). Apex locators are electrical devices that determine the working length and give the measurement by means of some ‘sound’ or ‘movement of a dial’ or ‘indicator’ when the correct position is reached. Figure 14.10 shows the photograph of commercially available apex locator. Principle: Apex locator compares the electrical resistance of periodontal membrane with that of gingiva surrounding the tooth, both of which should be similar. Difference in impedance is found between high and low frequencies at various sites in the root canal. Difference between two frequencies is less in coronal portion of canal.

Fig. 14.10  Commercially available apex locator (Courtesy of Dentsply)

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Difference between two frequencies increases in deeper portion of canal. Difference between two frequencies is highest at Cemento-Dentinal Junction (CDJ). Generations of apex locator: These have been discussed in detail in Chapter 11: Endodontic Armamentarium: Instruments, Materials and Devices. Components of apex locator: Discussed in Chapter 11. Factors determining accuracy of apex locators: Discussed in Chapter 11. Method: Generally a no. 15 K-file is used in the root canal held on the file clip to estimate the length since it gives apex locator readings efficiently and its tip well seen on the radiograph taken to confirm the position of the file within a root canal. Smaller files like no. 6, 8, 10 may not be wellappreciated on radiograph and may be loosely fitting in the root canal. Advantages • It precisely locates the position of apical constriction. (Accuracy up to 90% or more). • Reduction of radiation exposure by eliminating the need for multiple radiographs. One radiograph may be taken to confirm the readings given by apex locator. • Eliminates errors associated with radiographic image distortion. • Easy and quick method. • It is useful in verifying perforations, bifurcations of root and any obstructions. • It is very useful in maxillary molar teeth, where radio­ graphs may be difficult to read accurately due to radiopaque structures such as malar process and floor of maxillary sinus. • Useful in patients with gag reflex and in children who cannot tolerate placement of X-ray film and also a valuable tool in case of pregnant patients in whom the radiation exposure should be avoided. Disadvantages • Some of the earlier generation apex locators do not give accurate readings in presence of canal contents. • Erroneous readings are obtained in case where current flows into marginal gingiva or into metal restorations. • Inaccurate readings in case of low battery, blockage of canal and in too wet or too dry canal. • There can be difficulty in estimation of length in cases with wide open apex such as immature teeth. • Cannot be used in patients with cardiac pacemakers. This problem has been overcome in newer generation apex locators.

A mind-map to remember all points of working length is given in Figure 14.11.

Working Width/Apical Width/Apical Preparation One of the objectives of radicular preparation is to keep the apical opening as small as practically possible. Whether the apical width should be kept narrow or wide is a matter of debate with advantages and disadvantages of either of them. The aim is to reduce the intracanal microbial load as much as possible by preparing the apical canal areas so as to facilitate optimal irrigation and antimicrobial activity. ‘Apical width’ or ‘Working width’ is the term used for the size of the preparation to which the apical portion of the canal should be enlarged—Apical preparation. Apical scouting is the process of determining the anatomy and cross-sectional diameter of the apical 1/3rd of the root canal, based on which the final size to which the preparation should be enlarged, is estimated. Ruddle has suggested passing a series of K-files to working length to gauge the apical width. Grossman had recommended to enlarge a root canal to three sizes more than the first instrument that binds in the root canal or to enlarge it till all infected dentin is removed and clean, white dentinal shavings appear on flutes of the working instrument blade. However, these recommendations are no longer considered optimum for determining the apical width. Factors to be considered to determine apical width: Size of preparation of the apical portion varies from case to case and can be determined by considering following factors as given in Figure 14.12.

Advantages and Disadvantages • Wider apical preparation: – Advantages: - Ensures that all of the infected dentin has been removed. - Provides access to irrigating solutions and allows placement of intracanal medicaments in the apical portion to reduce the microbial load. – Disadvantages: - There is risk of errors in an attempt to make the apical preparation wider such as: ■ Apical perforation ■ Apical transportation ■ Overinstrumentation ■ Extrusion of irrigants and medicaments peri­ apically ■ Overextension of obturating material

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Fig. 14.11  A mind-map to remember all points of working length determination

- Not suitable for thermoplastic techniques of obturation in which there are more chances of overextension of obturation with wider apex. – Narrower apical preparation: - Advantages: ■ Minimal risk of preparation errors such as apical transportation, perforation, over instru­mentation ■ Reduced risk of extrusion of irrigants and medicaments periapically



■ Less chances of overextension of obturating material ■ Suitable for thermoplastic techniques of obturation. - Disadvantages: ■ Irrigants may not have access to the complexities of the apical third ■ Intracanal medicaments may not be properly placed. So, there may be compromised disin­ fection during interappointment period

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■ May not remove all infected dentin ■ It is not considered ideal for lateral compaction obturation. A mind-map to remember all points of working width is given in Figure 14.13.

Taper

Fig. 14.12  Mind-map showing factors determining apical width of root canal

Taper of the preparation is brought about by the taper of the instruments used for shaping of the root canal. Earlier, stainless steel hand instruments that were used had a constant taper of 2% (0.02) throughout the length of the instrument as per the ISO standards. Currently, instruments with greater tapers such as 4%, 6%, 8%, 10%, 12% have also become available made of Nickel-titanium.

Fig. 14.13  A mind-map to remember all points of working width

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It has been found that preparations with larger tapers and smaller apical width preparation can adequately disinfect the root canal.

WHAT ARE THE CURRENT CONCEPTS AND TERMINOLOGY FOR ROOT CANAL PREPARATION? Few Concepts and Terminology Apical Control Zone It is the area located in the apical third of the root canal system that demonstrates an exaggerated taper from the clinician defined apical constriction. Need for greater rate of taper of apical control zone (ACZ): • To provide resistance against condensation pressures of obturation. • To provide resistance/retention form to prevent extrusion of filling material. Apical Control Zone can be created by different techniques depending on Operator’s preference.

Coronal Scouting Initial process of determining the coronal and crosssectional diameter of coronal 2/3rds of root canal. Fine instrument sizes such as #8, #10, #15 in conjunction with a viscous chelator is used to explore, discover and secure the canal path in its coronal two-thirds. This is coronal scouting. These smaller files are called scouting files that are used initially in the canal before any radicular preparation is done. Scouting files are used to: • Determine the anatomy and cross-sectional diameter of root canal. • Confirm the presence or absence of straight-line access to the canal. When the handle of the file is off the longaxis of the canal it suggests lack of straight-line access as shown in Figure 14.14A. Figure 14.14B shows straight-line access of file in canal.

Apical Scouting Process of determining the anatomy and cross-section diameter of apical 1/3rd of root canal. Fine instrument sizes such as #8, #10, #15 can be used for apical scouting in conjunction with a viscous chelator to explore, discover and secure the canal path in its apical one-third. Apical scouting helps in determining the final size to which the preparation should be enlarged.

A

B

Figs 14.14A and B  (A) Handle of file of the long-axis; (B) Straight-line access of file in canal

Apical Gauging Process of determining the most apical cross-sectional diameter of the canal where a hand or rotary Endodontic instrument fits snugly at the terminus and resists any further apical travel. Thus, it confirms whether a uniform taper has been achieved in the apical one-third of the canal. It is recommended that the apical one-third of canal is prepared so as to have a deep shape with 8–10% taper. Apical gauging is usually done at the end of root canal preparation to determine the master apical file, i.e. the file used for final preparation of the canal based on which an appropriate corresponding master cone can be selected for obturation. After finishing the apical preparation, insert no. 20 K-file till length and tap on its handle (do not rotate). Check whether it is snug or loose. This is apical gauging. Use of Endo gauge: It has holes of different diameters into which the gutta-percha cone is placed to confirm the exact diameter to which the apical preparation of the canal has been done. Figure 14.15 shows the photograph of the Endodontic gauge.

Apical Tuning Apical tuning is the process to confirm that the diameter of the master apical file (MAF) represents the true size of the foramen.

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Fig. 14.15  Endodontic gauge (Courtesy of Dentsply)

Fig. 14.16  Apical tuning: Uniform backout of successively larger instruments at the interval of 0.5 mm

This is done by recapitulating using a series of successively larger instruments in sequence until those instruments uniformily back out of the canal. The interval of back out should not be more than 0.5 mm. Figure 14.16 shows apical tuning: Recapitulating with series of successively larger instruments no. 20, 25, 30, 35, 40, 50 and 60 diameter with 0.5 mm interval of backout.

Patency File Patency file is a small K-file (such as size #10) which is passively just pushed through the apical foramen to the radiographic terminus without causing its enlargement as shown in Figure 14.17. The concept of using patency file is controversial. • Points in favor of using patency file: – Patency file cleans the apical foramen – It prevents packing of debris in the apical portion of the canal – It helps to maintain working length by removal of accumulated dentinal debris and shavings produced as a result of instrumentation – It does not cause any apical enlargement. • Points against using patency file: – It might push contaminated debris periapically through the apical foramen. – It may mechanically injure the periapical tissues. – It may inoculate microorganisms periapically.

Fig. 14.17  Patency filing with no. 10 K-file

Apical Clearing Process of removal of loose debris from the apical extent of the root canal by using two to four successively larger instruments than the initial apical file at the working length. After final irrigation and drying, the last instrument is once again worked in the canal called as master apical file for the purpose of apical clearing.

Cleaning and Shaping of the Root Canal System Including Working Length Determination

Fig. 14.18  Push-pull motion

WHAT ARE THE DIFFERENT INSTRUMENT MOTIONS FOR EFFECTIVE SHAPING OF ROOT CANALS? Filing Motion (Fig. 14.18) • Filing motion is penetration and withdrawal, where the primary cutting action occurs on withdrawal. Also called as push-pull motion or rasping motion. • The instrument is to be placed into the canal till appropriate length and pressure is exerted against the wall of the canal. While maintaining pressure, the file is withdrawn from the canal. • The filing motion is carried out circumferentially to file all walls of the canal. • K-files are commonly used in filing motion. Hedstrom files bring about very effective filing motion. • Chances of apical transportation are more with filing motion.

Reaming Motion (Fig. 14.19) • Reaming motion is penetration, rotation and retraction, cutting action occurs on retraction. • The instrument is inserted in the canal till appropriate length and twisted clockwise one-quarter to one-half turn so that the instrument blades are engaged into the dentin and then the instrument is withdrawn.

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Fig. 14.19  Reaming motion: Penetration, rotation and retraction

• Reaming motion involving one-half turn before withdrawal can be used for preparing straight canals and that involving one-quarter turn before withdrawal can be used for slightly curved canals. • Reaming produces round, tapered preparation. • Reamers are used in reaming motion. Files can also be used in reaming motion. • Chances of apical transportation are less with reaming motion.

Watch-winding Motion • It is back and forth oscillation motion of instrument as it is advanced without applying any apical pressure. • This motion involves a quarter turn rotation using smaller size files such as #8 or #10. • It is most desirable during the initial phases of root canal preparation before coronal flaring is done. • The instrument is inserted to explore the canal with this motion. • There are less chances of preparation errors with this motion.

Rotary Motion • Continuous rotary movement with Nickel-Titanium rotary files is now the most commonly used motion for root canal preparation.

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• These instruments have reduced the potential preparation errors.

Balanced Force Technique Instrument Motion Balanced force hand instrumentation involves: • Insertion of instrument and advancing it in the canal in one-quarter turn clockwise rotation of less than 90o with slight or no apical pressure (Fig. 14.20A). • Second movement involves applying sufficient apical pressure to the instrument and rotating the instrument in half to three quarter turn counterclockwise rotation of 120o (Fig. 14.20B). • Third movement is to gently remove the instrument from the canal in clockwise rotation (Fig. 14.20C). These movements are carried out as the instrument is advanced towards the apex till the working length.

WHAT ARE THE REQUIREMENTS BEFORE STARTING CANAL PREPARATION? • An optimal coronal access preparation is a must before initiating the canal preparation. • There should be unobstructed straight-line access to the orifices of the canals. • The cusps or the incisal edges, which are going to be used as reference planes for working length determination should be flattened to get a stable reference point which is reproducible. • All the instruments that will be required for shaping of root canals must be sterilized and kept ready in an organized manner, i.e. in order of their sequence of use which saves time. • Before initiating the canal instrumentation, the preoperative radiograph should be carefully studied to know beforehand the canal anatomy or curvature or  any other irregularity that may be encountered during instrumentation to prevent any preparation mishaps. • For safe use of nickel-titanium rotary instruments in the canal without undue stress, most important requirements are: – Adequate coronal enlargement – Establishment of straight line access (SLA) to the canals. – Establishment of glide path with pathfinders or smaller K-files # 8, # 10, # 15 and even # 20.

A

B

C

Figs 14.20A to C  Balanced force technique instrument motion

WHICH ARE THE DIFFERENT ROOT CANAL PREPARATION TECHNIQUES? I.

The chronology of these techniques is as follows: A. Apical to coronal approach: – Standardized technique by Ingle in 1967 – Step-back technique by Mullaney in 1979 B. Coronal to apical approach: – Crown-down technique by Marshall in 1980 – Step-down technique by Goerig in 1982 – Balanced force technique by Roane in 1985 II. Root canal preparation techniques: – Hand instrumentation – Rotary instrumentation techniques – Ultrasonic and Sonic root canal instrumentation techniques – Laser-assisted root canal preparation techniques – Noninstrumentation technique (NIT)

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Apical to Coronal Approach Conventional/Standardized Technique of Root Canal Preparation (Ingle) The conventional technique considers two guidelines for instrumentation: • Root canal should be enlarged to atleast three sizes beyond the size of first instrument that binds in the canal. • Root canal should be enlarged till all infected dentin from the canal is removed and white clean, dentinal shavings appear on the blade of the instrument. This is no longer followed as it was found that: • Enlarging the canal to three subsequent sizes was insufficient in some cases, while in few cases it was found to be more than adequate. The degree of enlargement depends on the width and configuration of a particular root canal. • Color of dentinal shavings is not a reliable parameter and it is also not an indication of the presence of infected dentin. Step-back Method of Root Canal Preparation (Mullaney et al) The step-back method is the traditional canal preparation strategy which was in use for many years. • Other names: Telescopic technique, Flare method, serial root canal preparation. • Principle: Stepwise reduction of working length with increasing instrument sizes. The working length is reduced incrementally in 0.5 mm or 1 mm steps to create flared shapes having 0.10 or 0.05 taper respectively while using larger and stiffer instruments. • Step-wise procedure: A. For straight canals: Performed in following phases: - Locating apical constriction and cleaning of apical foramen (Phase I instrumentation): ■ Explore the canal with a fine instrument such as size #8, #10 in watch-winding motion and carry out gross debridement of the root canal. ■ Determine the working length. ■ Irrigation with 5.25% sodium hypo­chlorite. ■ Insert smaller sized file lubricated with a chelating agent and with instrument stop positioned to the correct working length in the canal. ■ File is engaged against dentinal wall and lateral pressure is exerted while maintaining the pressure, the file is withdrawn from the canal. Watch winding motion can be carried out with the file before it is withdrawn.

Fig. 14.21A  Circumferential filing

The procedure is repeated while carrying out circumferential filing around the entire perimeter of the canal for all the walls of the canal as demonstrated in Figure 14.21A. ■ It is necessary to irrigate the canal with sodium hypochlorite between each instrument use. Irrigation is done using a side-vented needle as demonstrated in Figure 14.22. This phase cleans the apical foramen. Now the preparation of the apical 1/3rd of the canal is started. - Preparation of apical 1/3rd of canal (Phase II): ■ Instrument stops are positioned about 0.5–1  mm short of the established working length. ■ Lubricated files are used in increasing sequence and the procedure of circumferential filing is repeated for this new working length. Figure 14.21B shows circumferential filing in apical third of canal. ■ Recapitulation: Previous smaller instrument is used till full depth periodically to prevent apical blocking with debris. - Preparation of body of canal: ■ Instrument stops are positioned at 0.5–1 mm lesser length than the length the previous instrument was used in a step-wise manner and larger files are used in the canal in sequence. ■ Circumferential filing is carried out until the file makes unforced contact with the

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Fig. 14.21B  Circumferential filing in apical third. Irrigation between each instrument use is a must

walls of the canal with irrigation in between instrumentation and recapitulation with smaller instruments periodically. Purpose of recapitulation: i. Prevent blocking with dentinal debris ii. Permit insertion of larger instruments to the working length iii. Smoothen the walls of the canal ■ The last file that was used for apical preparation called the master apical file is reinserted to the working length to maintain the patency of the apical segment. ■ Body of the canal is instrumented with three or four larger files in sequence with periodic recapitulation in between and copious irrigation with sodium hypochlorite after each instrument use. Figure 14.23 demonstrates the preparation of apical third and body of canal. - Preparation of coronal portion of canal (Phase II A): ■ Gates Glidden (GG) drills or Hedstrom files, one or two sizes larger than the previous instruments used in canal can be carefully used to flare the coronal portion of root canal as shown in Figure 14.24. - Refining phase of preparation (Phase II B): ■ It involves use of master apical file to smoothen all the walls and get a continuous

Fig. 14.22  Irrigation is done using a side-vented needle

taper from the apical constriction to the cervical canal orifice as shown in Figure 14.25. The step-back method aims at providing the final preparation as an exact replica of the original canal configuration, shape and taper, but only of larger size. • An example illustrating the step-back technique for instrumentation: A straight root canal with working length determined as 20 mm. Working length (WL) adjusted to: •  20 mm • 19 mm (WL minus 1 mm) (i.e. 1 mm short of apical foramen) • 18 mm (WL minus 2 mm) (i.e. 2 mm short of apical foramen

Size of file # 10, # 15, # 20, # 25 Use of # 20 for recapitulation # 30, # 35, # 40 Use of # 30 for recapitulation # 45, # 50, # 55 Use of # 50 for recapitulation

B. Curved root canals and other anatomic variations causing difficulty – Modifications for root canals with gentle curvature: - The instrument blade should be precurved as per the curvature and a directional silicone instrument stop should be positioned such that it indicates the direction in which the file has been curved. - Smaller K-files used in apical portion of root canal are flexible and can be precurved easily

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Fig. 14.23  Serial root canal preparation of apical third and body of canal

Fig. 14.24  Gates Glidden (GG) drill for coronal flaring

Fig. 14.25  Master apical file used for refining phase of preparation

but for larger inflexible files a diamond file or sandpaper disc is used to dull the flutes of the outer portion of the curve in apical segment of instrument to prevent preparation errors such as apical transportation. This is demonstrated in Figure 14.26. • Modifications for narrow root canals: – Since even the smaller files tend to bind in narrow canals, they should not be forced in the canal. – Smaller file is used till whatever length it penetrates without forcing and then the canal is irrigated with sodium hypochlorite.

– Instrument tip of a smaller file is modified by cutting about 1 mm from the end and smoothening it with a diamond file thus making a smaller file to act as an intermediate sized file as demonstrated in Figure 14.27. – Narrow canals should be enlarged to atleast size #25 or #30 K-files. • Modifications for double-curved or s-shaped canals: – After cleaning the apical foramen area, the curvature in the middle third of the root canal is carefully eliminated by filing with Hedstrom file to straighten the inner portion of the curve.

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Fig. 14.26  Schematic representation of modification of flutes of K-file. The outer portion of curve dulled with diamond file to prevent transportation of foramen in curved root canals (Courtesy of Dr Vishal Rathod)

– After eliminating the middle third curve, only the apical curve is left to be instrumented.

Advantages of Step-back Technique • Less chances of periapical trauma. • Develops an apical matrix or stop preventing over­ instrumentation and overfilling of root canal. • Also, greater pressure can be exerted during lateral compaction of gutta-percha facilitating filling of lateral canals. • Provides greater flare in the canal to provide dense obturation with gutta-percha. • Allows for removal of more debris.

Disadvantages of Step-back Technique • Full length may not be reached due to coronal binding caused by overhangs or obstructions in the coronal portions of root canal. As the canal is less tapered than instrument, the instrument binds somewhere coronally. • Narrow coronal portions of canal will prevent adequate passage of irrigating solutions to the apical portions of canal. • Due to limited irrigating solution, debris gets accumulated causing blockage. • Due to insufficiently enlarged coronal portion of canal, clinician has insufficient tactile control. • When a precurved negotiating file is inserted through coronally tight canal, the instrument gets straightened

Fig. 14.27  Modification of instrument to clean and shape narrow root canals

thus preventing proper instrumentation of the apical portion of canal. A mind-map to remember all points of step-back technique is given in Figure 14.28.

Coronal to Apical Approach Crown-down Technique of Root Canal Preparation (Marshall and Pappin) This is the most popular strategy for root canal preparation in present-day Endodontics. It can be performed using both hand and rotary instrumentation. • Other names: Pressure less technique, Step-down technique. • Rationale: – Pressureless coronal to apical movement minimizes or eliminates the extrusion of necrotic debris beyond the apical foramen. – Eliminates the coronal binding of instruments for controlled apical cleaning and shaping. • Step-wise procedure: – After access cavity preparation with unobstructed access to the root canal orifices, the access cavity is filled with a root canal irrigant (NaOCl). – Pre-flaring of the canal orifices with Gates Glidden drills in sequence. Orifice shapers of various Ni-Ti rotary systems such as profile orifice shapers can be used for pre-enlargement. – Establishing patency with smaller K-file such as no. 10 K-file.

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Fig. 14.28  A mind-map to remember the step-back technique

– Then a larger instrument is passively inserted into the canal till the depth it can advance without binding as shown in Figure 14.29A. – The next instrument one size smaller than the previous instrument is used to progress deeper in the canal. The third instrument follows and this process is continued till the tentative working length as shown in Figure 14.29B. – It is recommended that the files be lubricated with a chelating agent while using in the canal. - Copious irrigation with sodium hypochlorite in between use of instruments. - Recapitulation with smaller sized instruments to prevent blockage of debris. – Irrigate, recapitulate and reirrigate after every two to three instruments. – Determination of exact working length only after adequate coronal enlargement. Figure 14.29C shows adequate coronal enlargement of canal.

A

B

C

D

Figs 14.29A to D  Steps of crown-down technique of root canal preparation: (A) After coronal pre-flaring, larger instrument passively inserted into canal till the depth it can advance without binding; (B)  Instrument one size smaller than previous instrument used to progress deeper into the canal; (C) Adequate coronal enlargement; (D) Exact working length determined after coronal enlargement

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– Preparation of apical third of the root canal till the working length as shown in Figure 14.29D. – The final step in crown-down technique is the apical finishing involving apical gauging and apical tuning. • Advantages of crown-down technique: – It provides straighter, unimpeded access to the apical region of the canal by removing the coronal inter­ ferences. – It allows deeper penetration of irrigants. – It removes bulk of pulpal tissue and microorganisms and their products from the coronal portions of the canal. As a result it minimizes or eliminates the extrusion of necrotic debris beyond the apical foramen. – It eliminates the constraint of the apical enlarging instruments. – Flaring of the coronal 2/3rds of canal improves clinician’s tactile control of instrument preventing the preparation errors such as zipping. • Disadvantages of crown-down technique: This technique is relatively free of disadvantages when carefully performed to confine the instruments within the root canal space. Over-enthusiastic use of rotary files or GG drills should be avoided as it can lead to preparation errors such as perforations or can weaken the root structure predisposing it to fractures.

Step Down Technique of Root Canal Preparation (Goerig)

The current trend is to use a crown-down approach for root canal preparation involving enlargement of coronal portions of canal followed by preparation of apical portions of canal. Thus, it involves dividing the radicular preparation into coronal, middle and apical one-third as shown in Figure 14.30.

Step 1: Pre-enlargement/Coronal 2/3rds Preparation • Instruments used: Sequential use of Gates Glidden (GG) drills or various systems orifice shapers such as profile orifice shaper, etc. are used for coronal flaring. “Face off” the orifices with an appropriate size of Gates Glidden drill to create smooth glide path to facilitate placement of subsequent instruments. • Coronal scouting and shaping: Smaller K-files such as no.10 and then no. 15 are used for coronal scouting (i.e. inserting the file to a predetermined length estimated from a preoperative radiograph) to confirm the straight line access and to establish a glide path. • Benefits: – It allows for smooth, unobstructed path of the instru­ ment into the canal. – Gives better tactile control while using small precurved negotiating files in the apical portions of the canal. – It provides access for large amount of irrigating solution to reach the apical portion of canal and into various irregularities of canal.

• Other names: Coronal two-thirds pre-enlargement technique or reverse flaring technique. • Technique: i. After access Cavity preparation, hand instruments such as K or H files are used in the root canal till the length at which they bind in the canal. ii. Use of GG drills to flare the coronal third of the root canal. iii. Determination of working length for the tooth and creating an apical stop with no. 25 instrument. iv. Remaining canal is shaped in step-down approach, using a descending file sequence and progressing about 1 mm per consecutive instrument apically. v. Recapitulate with no. 25 instrument.

Modified Crown-down/Step-down Technique of Root Canal Preparation (Ruddle) There have been number of modifications of the step-down technique. One of the modifications is by Ruddle as follows:

Fig. 14.30  Radicular preparation divided into coronal, middle and apical one-third

Cleaning and Shaping of the Root Canal System Including Working Length Determination

– It facilitates removal of accumulated dentinal mud. – Since a bulk of pulp tissue and bacteria and their products have been removed by coronal enlargement, there are less chances of inadvertently inoculating them periapically. – It helps in easier location of the apical foramen. After the coronal scouting, the coronal two-thirds of the canal is shaped (Coronal Shaping).

Step 2: Scout to Terminus and Apical 1/3rd Preparation Apical scouting is the process of determining the anatomy and cross-sectional diameter of apical 1/3rd of root canal. Fine instruments such as size #8, #10, #15 can be used for apical scouting. It helps in determining the final size to which the preparation should be enlarged and also helps determine whether hand or rotary instruments should be used to finish the apical one-third preparation. This step involves: • Negotiating the apical one-third of canal • Establishing patency • Determining the exact working length • Establishing and confirming smooth glide path to the apical terminus.

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• Determining the working width, i.e. apical width to which the canal can be enlarged. • Shaping of the apical one-third of the canal (Apical shaping).

Step 3: Apical Finishing—Apical Gauging and Tuning This is the final step that completes the root canal preparation. It confirms whether uniform taper has been obtained in the apical 1/3rd. It involves: • Apical gauging: Process of determining the most apical cross-sectional diameter of the canal where a hand or rotary Endodontic instrument fits snugly at the terminus and resists any further apical travel. This is done usually at the end of root canal preparation to determine the master apical file used for final preparation of the canal based on which an appropriate corresponding master cone can be selected for obturation. • Apical tuning: Process of recapitulation by using a series of successively larger instruments in sequence until those instruments uniformly back out of the canal. A mind-map to remember all points of crown-down technique is given in Figure 14.31.

Fig. 14.31  Mind-map of crown-down technique

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TABLE 14.1  Step-back technique versus Crown-down technique Sr. No

Step-back Technique

Sr No.

Crown-down Technique

1.

Also called telescopic or serial root canal preparation

1.

Also called pressure-less or step-down technique

2.

Was used earlier. Now rarely used

2.

Most popular strategy in present-day Endodontics

3.

Uses hand instruments

3.

Uses both rotary along with hand instruments

4.

Involves apical preparation first followed by coronal preparation of canal

4.

Involves enlargement of coronal portions of canal first followed by apical portions of canal

5.

Beginning with smallest file close to apex and moving back from that point while increasing file size

5.

Beginning with larger file to remove coronal debris first and moving to smaller files as the files move closer to apex

6.

Causes coronal binding of instruments due to obstruction in coronal portions of root canal. As a result, full length may not be reached

6.

Since the obstruction in coronal portions of root canal are removed, eliminates coronal binding of instruments for controlled apical cleaning and shaping

7.

Narrow coronal portion prevents adequate passage of irrigating solutions to apical portions of canal

7.

Allows deeper penetration of irrigating solutions

8.

Debris accumulation which may get extruded beyond apical foramen

8.

Deeper penetration of irrigants facilitates removal of debris and eliminates its extrusion beyond apical foramen

9.

Obstructions in coronal portions of canal prevents straight, unimpeded access to the apical region of canal

9.

Provides straighter, unimpeded access to the apical region of the canal by removing coronal interferences

10.

Due to insufficiently enlarged coronal portion of canal, clinician has insufficient tactile control

10.

Coronal 2/3rds flaring improves clinician’s tactile control preventing preparation errors such as zipping

Step-back technique v/s Crown-down Technique

- Third movement is to gently remove the instrument from the canal in clockwise rotation as shown in Figure 14.32C.

See Table 14.1.

Balanced Force Technique of Canal Preparation Introduced by Roane et al. using a series of rotational move­ ments with ‘Flex-R files’, which is a new type of K-file. • Principle: Makes use of hand instruments to be positioned in the canal in a clockwise rotation followed by shaping the canal in a counterclockwise rotation. • Step-wise procedure: – Flaring of the coronal and middle thirds of the canal with GG drills in sequence so that most of the contamination from the canal is removed and there is passive movement of hand instruments into the apical third of the canal. – Balanced force hand instrumentation involves (Figs 14.32A to C): - Insertion of instrument and advancing it in the canal in one-quarter turn clockwise rotation of less than 90o with slight or no apical pressure as shown in Figure 14.32A. - Second movement involves applying sufficient/ slight apical pressure to the instrument and rotating the instrument in half to three quarter turn counter-clockwise rotation of 120o or more as shown in Figure 14.32B.

A

B

C

Figs 14.32A to C  Balanced force technique of canal preparation: (A) Insertion of Flex-R file into the root canal and turning it in clockwise direction ( 1 mm buccal reduction, lingual enamel present. 3. Thin remaining walls—Overlay (Composite/Ceramics) Tooth preparation guideline: Minimum 2 mm occlusal reduction. 4. Loss of occlusal anatomy—Endocrown (Composite/ Ceramics) Tooth preparation guideline: Minimum 2 mm occlusal reduction, extension into pulpal chamber.

Clinical Protocols for Restoring Nonvital Teeth with Full Prosthetic Restorations (As given in Cohen’s Pathways of Pulp, 10th Edn.) 1. Reduced walls but > ½ Crown height—Composite core Tooth preparation guidelines: Maintain all residual structures > 1 mm thickness (after core prep). 2. More than ½ coronal structure lost, reduced wall height - Composite core + Ceramic post or Composite core + in vitro fiber post Tooth preparation guidelines: Maintain all residual structures > 1 mm thickness (after core prep).

3. More than 2/3rds coronal structure lost, reduced wall height – Composite core + metal post or Amalgam core + metal post Tooth preparation guidelines: Maintain all residual structures > 1 mm thickness (after core prep). 4. More than ¾ coronal structure lost – Cast gold post and core (+/- porcelain) Tooth preparation guidelines: Maintain all residual structures > 1 mm thickness (after core prep) Internal walls divergent.

WHAT IS POST AND CORE RESTORATION? Post and core restoration is a foundation restoration that supports the coronal restoration (full coverage crown) in an extensively damaged Endodontically treated tooth.

Definition of ‘Post’ as given in Cohen’s Pathways of Pulp (9th Edn.) “Post is a restorative dental material placed in the root of a structurally damaged tooth in which additional retention is needed for the core and coronal restoration”. The post is either bonded or cemented into the root of the tooth and part of the post extends coronally to anchor the core.

Definition of ‘Core’ as given in Cohen’s Pathways of Pulp (9th Edn.) “Core is a restorative material placed in the coronal area of the tooth that replaces carious, fractured or missing coronal structure and retains the final restoration”. The core is anchored to the tooth either by its extension into the coronal aspect of the root canal or by means of an Endodontic post. Post and core are fabricated of different materials. So, the bond between the tooth, post and core is mechanical retention by means of luting or bonding agents. The post and the core, along with the luting or bonding agents to retain them, together form the foundation restoration. The specific design of the foundation restoration varies with the relative clinical need for each of the individual components. The tooth, the post, the core, the bonding or luting agents and the coronal restoration together form a monobloc (unified whole). Appropriate selection of each of the components is essential for the clinical success of the fully restored tooth.

Restoration of Endodontically Treated Teeth

Basic Components of the Fully Restored Tooth The basic components of the fully restored tooth include: • Remaining coronal and radicular tooth structure (Fig. 21.7d). • Restorative material in the root: post (Fig. 21.7c). • Restorative material in the pulp chamber and the coronal area replacing the missing tooth structure: core (Fig. 21.7b). • Restoration to protect the tooth and to restore the function and esthetics: Coronal restoration/crown (Fig. 21.7a). • Adhesive component to join each of the above components: Bonding or luting agents. The residual root and its attachment mechanism (supporting periodontium) must be preserved by Endodontic therapy followed by appropriate restorative treatment.

WHAT IS “FERRULE EFFECT” AND “BIOLOGIC WIDTH”? Ferrule Effect “The ferrule is a band of metal that encircles the tooth and greatly increases its resistance to fracture”. Ferrule is a protective ring which encircles the tooth. Restoration encirclement of tooth with a ferrule will protect

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Endodontically treated tooth against fracture by bringing about proper transmission of forces. Figure 21.8 a shows the diagrammatic representation of ferrule. • The ferrule must: – Be atleast 1.5–2 mm in height – Have parallel axial walls – Completely encircle the tooth (360o) – End on sound tooth structure and not on the restoration – Not invade the attachment apparatus. • Functions of ferrule: – Dissipates the force that concentrates at the narrowest circumference of tooth – Resists lateral forces from posts and leverage from crown in function – Increases resistance and retention of the restoration – Reduces the incidence of fracture in a nonvital tooth by reinforcing the tooth at its external surface. • Whenever there is loss of coronal tooth structure till the level of gingival margin and an effective ferrule cannot be given, then there is chance of fracture of tooth or early failure of restoration. In such cases, it is recommended to expose tooth surface by surgical crown lengthening procedure (CLP) or by Orthodontic extrusion to prepare the ferrule.

Biologic Width “The dimension of the junctional epithelial and connective tissue attachment to the root above the alveolar crest is called biologic width”. Figure 21.8b shows the diagrammatic representation of biologic width. In order to preserve the biologic width, the margin of the crown preparation should be about 2.5–3 mm away from the alveolar crest. Violation of biologic width during crown preparation ↓ Unexpected and uncontrolled bone loss around the tooth.

Ferrule Effect and Biologic Width: Implication

Fig. 21.7  a—Final coronal restoration (Crown); b—The core; c—The post; d—Remaining tooth structure; e—Apical seal preserved with 3–5 mm of gutta-percha

Ferrule of 1.5–2 mm above the margin of crown preparation (Ferrule effect). The margin of crown preparation about 2.5–3 mm above the alveolar crest (Biologic width). Thus, Ferrule effect + Biologic width = 4–5 mm of minimum tooth structure should be remaining above the alveolar crest for a successful restoration.

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• Post is mainly used to retain the core by the existing tooth structure, i.e. to anchor the post-core complex within radicular portion.

WHAT ARE THE REQUIRED CLINICAL CHARACTERISTICS OF POSTS? An ‘Ideal’ post should have combination of RFSS → Resilience Flexibility Strength Stiffness + Esthetics (when it has to be used for anterior teeth).

Required Clinical Characteristics Fig. 21.8  a—Ferrule effect; b—Biologic width

WHAT ARE THE INDICATIONS FOR USING POSTS? Indications 1. Extensive loss of coronal tooth structure where subsequent core built-up cannot be easily retained by the existing walls of the tooth. 2. When more than 50% of coronal tooth substance is lost or less than 2/3rds of sound tooth structure remains and the displacement forces will dislodge the restoration. 3. When adjacent surface axial walls of the tooth are lost. For example, buccal and distal axial wall or buccal and mesial axial wall in case of a molar. 4. When no axial wall of the coronal part of the tooth remains, i.e. decoronated tooth.

Few Facts About ‘Posts’ to Eliminate Misconceptions • Posts do not strengthen the tooth or prevent fracture (Strength of the tooth is related directly to the bulk of remaining dentin and the surrounding alveolar bone). • Posts may actually weaken the tooth, as the central core of dentin is removed and root is made hollow for post space preparation. • All Endodontically treated teeth do not need posts (Extensive loss of coronal tooth structure is indication).

1. Posts should provide maximal retention within the root 2. Posts should provide maximal retention of the core and the crown 3. Posts should provide protection of root from fracture 4. Posts should provide protection of apical seal from bacterial contamination caused by coronal leakage 5. Posts should be easy to remove (retrievability) 6. Posts should provide light transmission and pleasing esthetics, when indicated 7. Posts should be biocompatible 8. Posts should be radiopaque 9. Posts should have fatigue resistance 10. Posts should have high strength.

WHAT ARE THE DIFFERENT TYPES OF POSTS? Classification of Post Systems • According to the material of which posts are made:

Restoration of Endodontically Treated Teeth

• According to the method of their fabrication:

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Post Systems in Detail Rigid Posts

• According to mode of use:



Active posts are no longer used.

• According to their shapes:

Esthetic: Zirconia posts: • Zirconia post is an all-ceramic post, composed of zirconium oxide (ZrO2) • Advantages: Esthetic – Extremely radiopaque – High flexural strength – High fracture toughness – Excellent resistance to corrosion – Very rigid (stiffest of all rigid posts) • Disadvantages: – Brittle – Cannot be cut or removed from the canal if Endodontic retreatment has to be done – Have poor resin bonding. Failure at cement/post interface can occur due to poor bond strength of the resin composite cement to zirconia posts – If zirconia posts fracture, since they are not retrievable from the roots, they will render the roots unrestorable. • Zirconia posts are available with a smooth surface configuration with no grooves or serrations or roughness.

Nonesthetic • These include metallic posts composed of crown and bridge alloys, stainless steel or titanium-titanium alloy. Figure 21.9 shows photograph of commercially available preformed metal posts of different sizes.

• According to their design:

Fig. 21.9  Commercially available preformed metal posts in a box (Courtesy of Mr Amar, Dr Dabholkar’s clinic)

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Figure 21.10 shows photograph of preformed metal posts along with their corresponding postspace preparation drills. • Advantages: – Rigid: Made of stiffer materials which do not fracture or bend easily – Radiopaque – Dissipate functional forces along the length of root and the periodontal structures. This is an important consideration when there is minimal remaining tooth structure for crown margins. – Cervical stiffening is provided that protects the crown margins and resists leakage. • Disadvantages: – Failure of metal posts can cause root fracture (Induces root split) – Stainless steel posts contain nickel, an allergen, that can leach out through dentinal tubules into the tissue – Corrosion of stainless steel posts – Nonesthetic.

Studies have shown that nonrigid posts tend to exhibit fewer catastrophic irreversible root fracture. Data indicates that nonrigid fiber posts are acceptable alternatives to metallic posts and can be used clinically wherever metal posts have been used.

Nonrigid Posts

•

They are composed of glass, quartz or carbon fibers embedded in a resin matrix. These are fiber-reinforced resin-based composite posts which are used with bonded resin-based composite core built-ups. In modern dentistry, these nonrigid posts have become quite popular.

Advantages of Nonrigid Posts •

• •

• • • • • • • •

Designed to have physical properties similar to dentin Modulus of elasticity of dentin: 18 GPa Modulus of elasticiy of fiberposts: 17–25 GPa. The primary benefit of lower modulus of elasticity is protection of root from fracture (fiber posts prevent root split) through reduction of transfer of forces through the post to the root. Fiber-posts are resilient posts that flex with the tooth under function, thus reducing the transfer of force to the root and reducing the risk of root fracture. They are easily retrievable if Endodontic retreatment has to be done. Light transmitting posts and bonded composite provide increased fracture resistance by reinforcing weakened roots. Fiber posts do not cause any stress concentration. Fiber posts are safer. In case of failure of fiber posts, fracture of post occurs, which can be removed and replaced, rather than fracture of the root. No corrosion. Good esthetics with quartz and glass fiber-reinforced posts. High tensile strength. High fatigue strength. Glass fiber posts can transmit curing light to internal area of root. So, dual-cure adhesive cements can be used. Fiber posts are adhesively bonded in the root and composite fiber post with composite resin core. All this gives good bond between individual components of monoblock.

Disadvantages of Nonrigid Posts

Fig. 21.10  Preformed metal posts along with their corresponding postspace preparation drills (Courtesy of Dr Chetan Shah)

• Little to moderate radiopacity may be difficult to visualize on radiographs. • In case of structurally compromised teeth, there is lack of cervical stiffness from dentin. Excessive post flexion in such teeth may be detrimental to marginal seal. • Primary mode of failure of nonrigid posts is decementation of post from root.

Restoration of Endodontically Treated Teeth

Types of Nonrigid Posts 1. Glass fiber-reinforced epoxy resin posts: Composed of Glass or silica fibers. Glass fibers can be made of different types of glasses such as high-strength, electrical glass, or quartz fibers. Glass fibers in the matrix increase the strength of the post. Glass fiber-reinforced posts have high fatigue strength, high tensile strength and modulus of elasticity closer to dentin. Contact of glass fiber reinforced posts with oral fluids reduces their flexural strength. Figure 21.11 shows photograph of commercially available packet of glass fiber posts. 2. Polyethylene fiber-reinforced posts: Composed of ultrahigh molecular weight polyethylene woven fiber ribbon. This polyethylene woven fiber ribbon is coated with a dentin bonding agent and packed into the canal, where it is then light polymerized in position. These posts protect the remaining tooth structure. This is because for these posts, the root canals are not enlarged, the undercuts present in the root canal are not removed and 1.5–2 mm crown ferrule is formed. 3. Carbon fiber-reinforced epoxy resin posts: Composed of unidirectional carbon fibers parallel to the long-axis of the post in an epoxy resin matrix. These posts have high fatigue strength, high tensile strength and modulus of elasticity similar to dentin.

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Available as smooth or serrated posts. Contact of these posts with oral fluids reduces their flexural strength. When the tooth is structurally compromised, the carbon fiber reinforced post may flex under functional load causing micromovement of the entire core.

WHAT ARE THE CLINICAL PARAMETERS FOR POST SELECTION? While selection of post or while preparation of post space or while using post, one key guiding principle that should be kept in mind is preservation/conservation of remaining tooth structure. Traditionally, the metal (rigid) posts have been widely used. Earlier, the choice of whether rigid or nonrigid posts should be used, was based on two considerations: 1. The amount of remaining tooth structure. 2. The anticipated forces in each clinical circumstance.

Amount of Remaining Tooth Structure Based on this, a simple rule that was followed is: • Teeth with more than 50% of tooth structure remaining: Post not needed • Teeth with 25–50% of tooth structure remaining: Use nonrigid post • Teeth with less than 3–4 mm of vertical height or when less than 25% of tooth structure is remaining: Use rigid post. But, now-a-days, use of Rigid posts has declined because of its potential to cause root fracture. In almost all clinical situations requiring posts, one of the nonrigid posts is preferred.

Anticipated Forces in a Given Clinical Circumstance

Fig. 21.11  Commercially available pack of glass fiber posts (Courtesy of Dr Chetan Shah)

• Occlusal forces are transmitted through the core and the post and ultimately distributed along the length of the root. The more, the posts, cements and restorative materials will behave like dentin, the less, the force will be concentrated between the component and the root during function. Types of post Stress concentration •  Stainless steel Increased stress concentration •  Titanium Less stress concentration •  Fiber posts No stress concentration • The posts and their associated core/crown complex tend to undergo repeated lateral forces during function.

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• Biting and parafunctional habits such as clenching or Bruxism transmit nonaxial shear, tensile and compressive forces to a post in the root. In case of structurally weak teeth, force concentration in the root can predispose the root to fracture. With very little amount of tooth structure remaining, and minimal or no crown ferrule to resist force, more force will get transferred to the post. Post flexure of nonrigid posts under occlusal loads may result in micromovement of the core that causes disruption of the cement seal and leakage or may result in loss of the core and the crown.

Clinical Parameters for Post Space Preparation and Post Selection Apical Seal It has been found that atleast 5 mm of gutta-percha is required for an adequate apical seal. If less than this is left behind, there are high chances of leakage.

• Molars: Posts are placed in – Palatal roots of maxillary molars – Distal roots of mandibular molars. In distal roots of mandibular molars, the post space drills larger than size #3 GG drill should not be used.

Root Anatomy • Root concavities should be considered. Maxillary first premolars have deep mesial concavities. Maxillary first molars have deep concavities on the furcal surface. • Root curvatures should be considered. Generally, root curvatures occur in the apical 5 mm of the root. Therefore, when 5 mm of gutta-percha is retained apically, the curved portions of the root are usually avoided. In case of greater curvature, limit the post length so as to preserve dentin, thereby preventing root fracture or perforation. • Root canal shape: Maxillary premolars and mesial roots of mandibular molars have elliptical or ribbon shaped canals and post space preparation should be avoided in those.

Post Size/Length and Post Diameter

The integrity of apical seal is proportional to the amount of Endodontic filling material. Original full length root canal fillings have a superior seal compared with 3, 4, 5 or 7 mm of apical gutta-percha.

Post Space The residual dentin of the root canal should undergo minimal alteration to accept the post. Preparation of post space should not enlarge the root canal at the expense of dentin. At least 1 mm of tooth structure must remain circumferentially around the post to prevent perforation and provide fracture resistance.

Root Selection for Post Placement in Multirooted Teeth • Premolars: Posts are placed in – Palatal root of maxillary premolar – Straightest root of mandibular premolar. It is found that in case of maxillary premolars, if 1–2  mm of preparation is done in the buccal root, it serves as an antirotational lock.

• Post length: – Post should be long enough to satisfy clinical requirements while maintaining the root integrity and the apical seal. – Recommendations for post length: - Post length equal to or greater than the crown length (incisocervical/occlusocervical dimension) of the tooth is recommended. - Generally, apical seal dictates the post length. Retaining atleast 5 mm of apical gutta-percha and extending the post to the gutta-percha. - In case of teeth with long roots, post of approximately 3/4th the length of the root, while maintaining the apical seal, can be considered. - Alveolar bone height also influences the post length. Occlusal forces generate the least risk to the remaining tooth structure when post extends atleast 4 mm apical to the alveolar crest. - In case of molars, the post should not extend more than 7 mm apical to the root canal orifice. – Studies show that: - When post length is equal or greater than the length of the crown, the success rate has been found to be 95–100%.

Restoration of Endodontically Treated Teeth

- When post length is shorter, then the success rate has been found to be the same as for the restoration without the post in such teeth. – Problems with very long posts:

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• High Compressive strength, Contrasting Color to tooth for better distinction in posterior teeth • Dimensional stability • Ease of manipulation, Esthetics (for anterior core builtup) • Short Setting time.

WHAT ARE THE DIFFERENT TYPES OF CORE MATERIALS?

– Problems with very short posts: - Causes transfer of forces to unsupported root, extending above the alveolus. This can result in root fracture. - Short posts are less retentive. Loosening of post causing restoration failure can occur. • Post diameter: – Diameter of the post should be the minimum dimension to withstand functional loading. – Recommendations for post diameter: - Preserve radicular dentin. The post space preparation drills should be related in size to root dimensions to avoid excessive post diameters that can lead to root perforation. - Permit tooth to resist fracture. At least 1 mm of tooth structure must remain circumferentially around the post. - Post diameters should not exceed one-third of root diameter in any location. Safe diameters for post space preparation drills are: i. 0.6–0.7 mm for smaller teeth such as mandibular incisors. ii. 1–1.2 mm for larger diameter roots such as maxillary central incisors. A mind-map to remember clinical parameters for postspace preparation and post selection is given in Figure 21.12.

WHAT ARE THE REQUIRED PHYSICAL CHARACTERISTICS OF THE CORE? (Remember the alphabetic formula: ABCDE ST) • The core material should have an Ability to bond to both—the tooth and the post • Biocompatibility

Metallic Core Materials • Amalgam core – Advantages: - High compressive and tensile strength - High modulus of elasticity - Easy manipulation and short setting time - Highly retentive when used as coronal-radicular restorations or with preformed metal post in posterior teeth - Improved seal with bonded amalgam procedures at tooth-alloy junction – Disadvantages: - Corrosive - Discoloration of gingiva or remaining dentin - Safety and environment issues. • Cast core: – Advantages: - Cast core is an integral extension of post - Does not depend on mechanical means of retention - So, no chances of dislodgement of core and crown from post and root, even when the amount of tooth structure remaining is minimal - Noble metals used in cast core are noncorrosive. – Disadvantages: - Increased incidence of root fracture, since valuable tooth structure is removed to create path of withdrawal - Procedure requires several appointments and laboratory involvement. So it is expensive. - Fracture of metal can occur at the postcore interface resulting in restoration failure.

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Fig. 21.12  A mind-map to remember the clinical parameters for post space preparation and post selection

Nonmetallic Cores • Composite resin core – Advantages: (Almost fulfils ABCDEST) - Adhesive bonding to tooth structure and many posts. - Biocompatible - Compressive strength is high - Dimensional stability - Ease of manipulation - Rapid Set (Short setting time) - Opaque (for nonesthetic areas) and translucent (for esthetic, anterior zones) and various colored formulations are available (Color Contrast). – Disadvantages: - Microleakage

- For adequate retention, the dentin bonding agents must be compatible with composite core materials. For example, self-cure composite resin will be incompatible with light-cured adhesive. - Zinc oxide eugenol used as root canal sealer or as a temporary restoration, inhibits the setting of composite resins. - Bond strength of composite resin core to dentin requires complete setting of resin materials. Figure 21.13 shows photograph of commercially available composite core built-up material. • Glass ionomer core – Advantages: - Anticariogenic due to fluoride release - Forms chemical bond with tooth

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Step 1: Post Space Preparation

Fig. 21.13  Commercially available core built-up material (Courtesy of Mr Amar, Dr Dabholkar’s clinic)

• Post space is prepared by removal of gutta-percha from the root canal using hot instrument (Thermal method) or rotary instruments such as gates glidden drills, Peeso drills or specially designed post space preparation drills (Mechanical method) without disturbing the apical seal. • At least 5 mm of apical gutta-percha should be left behind for a good apical seal. • Conservation of root dentin should be the goal of post space preparation. Little or no dentin should be removed from the root, i.e. Postspace preparation should not enlarge the root canal at the expense of dentin. • Desired post length, the bone height and the root morphology are the factors to be considered while post space preparation.

Step 2: Post and Core Restoration – Disadvantages: - Low strength - Low fracture toughness - Low retention when preformed posts are used - Solubility and sensitivity to moisture - Insufficient strength to be used as core for the tooth to serve as abutment for bridge. • Resin-modified glass ionomer core: (Composite resin + glass ionomer) – Advantages: - Moderate strength - Satisfactory core material for moderate size builtups - Anticariogenic - Higher bond strength - Minimal microleakage. – Disadvantages: - Hygroscopic expansion may result in fracture of ceramic crowns - Solubility between glass ionomer and composite resin.

WHAT IS THE TECHNIQUE OF FABRICATION OF FOUNDATION RESTORATION? Clinical procedure involves: • Step 1: Post space preparation • Step 2: Post and core restoration.

Using Preformed Post Followed By Core Built-up • Commonly used technique nowadays. • This system makes use of appropriate post space preparation drills to prepare the post space of desired length measured from a fixed coronal landmark till the point in the root canal up to which the gutta-percha is to be removed retaining atleast 5 mm of gutta-percha apically and depending on other factors as shown in Figures 21.14A to E. • After the post space is prepared, the post corresponding to the drill is placed in the prepared space to check the length and fit. • The extra length of the post is cut using air-rotor handpiece with a water coolant. • The post is then bonded or cemented in place as shown in Figure 21.14F.

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A

B

F

C

G

D

H

E

I

Figs 21.14A to I  Steps involved in restoring an endodontically treated tooth using preformed-post technique: (A) An Endodontically treated tooth with very little sound coronal tooth structure, indicated for post and core restoration; (B) Gates Glidden drill no. 1 is used to remove the gutta-percha from the coronal third of the root; (C) Alternatively a Peeso drill can also be used for removal of gutta-percha to the desired length so as to preserve about 3–5 mm of gutta-percha for the apical seal; (D) The post space preparation drill is used to remove the guttapercha to the required length; (E) This is a special drill to create a positive stop for post head/hub increasing the retention of post; (F) Post bonded or cemented in place; (G) Core built-up; (H) Preparation of tooth to receive full coverage coronal restoration; (I) A completely restored Endodontically treated tooth

• Core material is then placed around the post into the remaining pulp chamber and is built-up to form the coronal area as shown in Figure 21.14G. • The tooth is then prepared to receive a full coverage restoration as shown in Figure 21.14H. • Figure 21.14I shows a completely restored Endodontically treated tooth.

Cast Post and Core • Direct technique: – This involves intraoral fabrication of a castable post and core pattern on the prepared tooth. – Prefabricated plastic postpattern is seated in the post space and autopolymerizing acrylic resin can

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be used to reline the post pattern to fit the post space. – Using the same resin, the core is made over the post pattern and is contoured intraorally to the desired form. – After removing the finished pattern from the tooth, it is sent to the laboratory for casting. – In the next appointment, cast post and core is seated in the post space; any obstructions if present are corrected and then the cast post and core is passively cemented. • Indirect technique: – This technique involves making a final impression of the prepared tooth and post space and sending it to the laboratory for die preparation and subsequent fabrication of cast post and core. – For making impression of the prepared post space, impression material needs to be reinforced with plastic pin or metal wire to achieve an undistorted impression. Safety pin can also be used for reinforcing impression material. – Also, various plastic impression posts are available in the market which make the procedure easy. In this, the clinician has to select the desired diameter of plastic post, use the corresponding drill to prepare the post space at appropriate length. Place the plastic post. Then light body rubber base impression material is injected into the canal. When it sets, remove and send it to laboratory. – In the next appointment, cast post and core is seated in the post space; any obstructions if present are corrected and then the cast post and core is passively cemented. Harmful hydraulic pressures can be generated inside the root that can crack the root if the cast post and core is rapidly seated or seated with heavy pressure or if excessive cement is used. Cast post and core is not commonly used nowa-days.

Coronal Coverage • After the fabrication of the foundation restoration, the final step in Endodontic reconstruction is coronal coverage. • The rule is to give a coronal coverage restoration for most Endodontically treated posterior teeth and all structurally damaged anterior or posterior teeth.

Fig. 21.15  Causes of failure of post and core restorations

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Purpose of coronal coverage: • To distribute functional forces • To protect the tooth against fracture • To re-establish function • To isolate the dentin and Endodontic filling from microleakage.

WHAT ARE THE CAUSES OF FAILURE OF POST AND CORE RESTORATIONS? Causes of Failure of Post and Core Restorations (Fig. 21.15) Causes of failure: Fracture of root, (F7) Fracture, bending or distortion of post, Fatigue failure, Fit of post affected, i.e. loosening of post or loss of retention of post Ferrule of adequate amount missing, Flexion, Forces. It has been found that loss of retention and tooth fracture are the two most common causes of post and core failure.

Why Roots Fracture? Fatigue failure: Structures subjected to low but repeated forces (cyclic loading), may appear to fracture suddenly for no apparent reason. This phenomenon is called fatigue failure, which is a progressive failure that proceeds by initiation and propagation of cracks. Since the teeth are constantly subjected to fluctuating cycles of loading and unloading during mastication, fatigue failure of dentin, posts, cores, crown margins or adhesive components is likely to occur resulting in tooth/root fracture. Moreover, if the tooth has minimal tooth structure remaining, fatigue can cause Endodontic posts to bend permanently or break,

Fig. 21.16  Forces (a) exerted on a weak root from a rigid post resulting in root fracture (b)

or it can cause a fiber-matrix complex to disintegrate. Fatigue failure of nonvital tooth restored with a rigid post is likely to cause complete fracture of the root as the rigid post has higher modulus than the root dentin, the stress concentration occurs adjacent to the bottom of the post resulting in root fracture originating at the apex of a rigid post. Figure 21.16 shows diagrammatic representation of rigid post exerting forces on a weak root resulting in root fracture.

BIBLIOGRAPHY 1. Cohen S, Hargreaves KM. Pathways of Pulp, 9th edn. St. Louis: Mosby; 2006. pp. 786-818. 2. Hargreaves KM, Cohen S. Pathways of Pulp, 10th edn. Mosby Elsevier, St Louis, MO; 2011. pp. 777-804. 3. Ingle J, Bakland L, Baumgartner J. Ingle’s Endodontics, 6th edn. BC Decker Inc, Hamilton; 2008. pp. 1431-64.

CHAPTER

22

Endodontic Failures and Nonsurgical Endodontic Management

This chapter tells you about the causes of post-treatment Endodontic disease and explains in detail how nonsurgical Endodontic retreatment can result in healing and thus saving the involved tooth.   You must know • What is the Outcome of Endodontic Treatment? • What are the Measures to be Employed to improve the Rate of Success of Treated Endodontic Cases? • What are the Causes of Endodontic Failures? • How do you Diagnose Post-treatment Disease? • What is the Treatment Plan for the Patient with Post-treatment Disease? • What are the Indications and Contraindications of Endodontic Retreatment? • What are the Factors to be Considered for Endodontic Retreatment? • What are the Steps for Nonsurgical Endodontic Retreatment? • What is the Prognosis of Endodontic Retreatment?

WHAT IS THE OUTCOME OF ENDODONTIC TREATMENT? Goal of Endodontic Treatment

Broadly, it can be said that the Endodontic therapy is directed towards a specific goal: ‘To prevent or cure periradicular periodontitis’ (Apical periodontitis). The outcome of Endodontic treatment—success or failure is explained in Flow chart 22.1.

WHAT ARE THE MEASURES TO BE EMPLOYED TO IMPROVE THE RATE OF SUCCESS OF TREATED ENDODONTIC CASES? Molven and Halse have said:



‘Success depends on: – Elimination of root canal infection present when treatment starts – Prevention of both contamination during treatment, and prevention of reinfection later. So, success rates reflect the standard of the cleaning, shaping and filling of root canals’. To ensure nearly 100% success rate, Ingle has recommended to follow ten rules which can be considered as the ten commandments of Endodontics. Let us remember the ten commandments of Endodontics given by Ingle with the following true statement: Careful Application of Root Canal Laws and Principles Can Cause Successful Treatment (C = Case selection, A  =  Apical density, R = Restore, C = Cavity preparation, L  =  Length, P = Practice, C = Curved, C = Cone, S = Surgery, T = Treatment) • Use great care in Case selection. Choose proper cases for Endodontic treatment and reject those that will obviously fail.

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Short Textbook of Endodontics Flow chart 22.1  Outcome of Endodontic treatment

surgical treatment, and this should be done by using a sharp right-angled explorer. • Properly Restore each treated pulpless tooth to prevent coronal fracture and microleakage. • Practice Endodontic techniques on extracted teeth mounted in acrylic blocks to improve your skills to carry out the procedures well in the patient’s mouth.

WHAT ARE THE CAUSES OF ENDODONTIC FAILURES?

Microbial

• Use greater care in Treatment. Do not hurry, maintain an organized approach. Be certain of instrument position and procedure before progressing. • Establish adequate Cavity preparation. Access cavity can be improved by modifications of coronal preparation. Radicular preparation can be improved by thorough canal cleaning and shaping. • Determine the exact Length of tooth to the foramen and be certain to operate only to the apical stop, about 0.5–1 mm from the external orifice of the foramen. • Always use Curved, sharp instruments in curved canals, and especially remember to clean and reshape the curved stainless steel instrument each time it is used. • Use great care in fitting the primary filling point/Master Cone. The apical portion of the canal must be obliterated. Ensure total obturation of the entire root canal. Always use root canal sealer cement. • Use Periradicular Surgery only in those cases for which surgery is definitely indicated. • Always check the Apical density of the completed root canal filling of the patient undergoing periradicular

Microbial infection persisting in the apical portion of the root canal system is the major cause of Endodontic failure. Intraradicular infection is the essential cause of primary apical periodontitis and major cause of post-treatment apical periodontitis. Microorganisms may be left behind in the apical portion of the complex root canal system due to improper root canal treatment procedures. Microorganisms may be found as biofilm located within small canals, lateral or accessory canals or in the space between root fillings and canal wall of incomplete obturated canal.

Nonmicrobial True cysts, cholesterol crystals, foreign bodies in periapical area are the nonmicrobial causes of Endodontic failure. Healing by scar tissue formation may be misdiagnosed as radiographic sign of Endodontic failure.

Flora Associated with Root Canal Treated Teeth • Bacteria, yeasts, fungi, mixed anaerobic microbiota, viruses, may be found. • Gram +ve cocci, rods and filaments may be the bacteria found. • Mostly species belonging to genera Actinomyces, Enterococcus and Propionibacterium. • Enterococcus faecalis is commonly isolated from failing root canal treated teeth and it is known to be especially

Endodontic Failures and Nonsurgical Endodontic Management

difficult to eliminate with standard instrumentation and irrigation. – It can tolerate pH up to 11.5 – It can survive prolonged starvation – It is resistant to most of the intracanal medicaments – It can grow as microinfection in treated canals without any synergistic support from other bacteria. Actinomyces israelli and P. propionicum may establish themselves extraradicularly even after treatment. The extra­ radicular microbial infection may be the cause of failed Endodontic treatment. It has been found that bacteria may not be completely eliminated after thorough cleaning, shaping and disinfection. This “critical amount” of bacteria that persists can sustain periradicular inflammation. Overaggressive instrument action can cause extrusion of bacteria through the apex into the periapical tissue and can serve as a continuing irritant. An obturated canal may be recontaminated from coronal leakage. Gutta-percha root canal fillings do not resist salivary contamination. Bacteria can penetrate from crown to periapex alongside poorly obturated canals. Quality of coronal seal determines the long-term prognosis of treatment.

Grossman Classification

Stabholz et al. and Friedman Classification

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Other Classification



These have been explained in detail in Flow chart 22.2.

HOW DO YOU DIAGNOSE POST-TREATMENT DISEASE? 1. Thorough review of patient’s health history 2. Clinical examination: Visual, extraoral, intraoral and periodontal evaluation – Signs of inflammation – Tenderness to percussion – Presence of sinus tract – Infection 3. Radiographic assessment : Multiple angulated radiographs, Bitewing radiographs. In cases of previous Endodontic therapy, radiographs can help evaluate caries, defective restorations, periodontal health, quality of obturation, periradicular pathosis, perforations, fractures, resorption and canal anatomy. Figures 22.1 and 22.2 are radiographs showing periapical radiolucency in root-canal treated teeth indicating recurrent infection. 4. Periradicular tests: Percussion, palpation and bite test. 5. Pulp vitality tests: When there is vital tissue remaining in the canals of a previously treated tooth due to missed canal or improperly cleaned canal, patients may complain of sensitivity to heat or cold. Pulp vitality tests can help to assess this situation.

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Short Textbook of Endodontics Flow chart 22.2  Classification of causes of Endodontic failure

Fig. 22.1  Radiograph showing recurrent periapical infection in root canal treated mandibular premolar due to unusual anatomy

Fig. 22.2  Recurrent periapical infection in poorly shaped and filled canals and mesial canal blocked with separated instrument

Endodontic Failures and Nonsurgical Endodontic Management

WHAT IS THE TREATMENT PLAN FOR THE PATIENT WITH POST-TREATMENT DISEASE? Post-treatment apical periodontitis should be diagnosed and its cause should be detected. Treatment options for a case of Endodontic failure: Option 1: Wait and watch when etiology of the condition remains unknown. Option 2: Extraction of tooth: It may be a desirable option in certain cases. Recent advances in prosthetic reconstruction and dental Implantology have made it possible. Option 3: Nonsurgical retreatment—Preferred choice as it is less traumatic, less invasive, preserves the tooth. Option 4: Surgical retreatment—Periradicular curettage, apical root resection, root amputation, intentional replantation are various surgical treatment options. The choice of which option to undertake, is determined by: • Knowledge and experience of clinician • Patient considerations.

WHAT ARE THE INDICATIONS AND CONTRAINDICATIONS OF ENDODONTIC RETREATMENT? Indications • Endodontically treated teeth presenting with symptoms such as tenderness to percussion, swelling, fistula, or signs of infection. • Endodontically treated asymptomatic tooth with improperly done treatment such as inadequate filling viewed radio­graphically. Patient should be informed. Retreatment may be postponed but must be done before prosthetic treatment for that tooth. • Generally, periapical radiolucencies that have not healed or decreased in size or have increased in size in a period of 4 years evidenced by follow-up radiographs should be considered for retreatment. • Root canal fillings which have been exposed to oral environment for long period of time due to lack of coronal seal by means of permanent coronal restoration can be considered infected and retreatment may have to be done.

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• Vertical root fracture • Untreatable root perforations • If the tooth with root canal failure is not important strategically such as diseased maxillary 2nd molars with no opposing tooth or having developed class I or class III occlusion or articulating with another tooth. • Tooth that is hopelessly nonrestorable such as extensive caries or coronal fracture approaching or entering the furcation or biologic width. • Unfavorable root anatomy • Procedural complications such as nonretrievable separated instrument, irreparable perforation, ledge, etc. Operating the tooth with dental operating microscope (DOM) and Surgical Endodontics is better choice than extraction of tooth in most of the above cases.

WHAT ARE THE FACTORS TO BE CONSIDERED FOR ENDODONTIC RETREATMENT? The factors to be considered for Endodontic retreatment are given in the form of mind-map in Figure 22.3.

WHAT ARE THE STEPS OF NONSURGICAL ENDODONTIC RETREATMENT? • Access cavity preparation (coronal radicular access): – Retreatment access is challenging and differs from that of primary treatment. – Goal: To establish straight-line access to apical area of root canal system while conserving as much tooth structure as possible.

Contraindications As such, there is no absolute contraindication of Endodontic treatment or retreatment. But teeth with the following conditions if indicated for retreatment may have poor prognosis: • Untreatable root resorption • Terminal periodontal disease

• Recleaning and reshaping: – Correct length of canal is established. – Reinstrumentation and reshaping using the crowndown technique.

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Fig. 22.3  A mind-map to remember all factors to be considered for retreatment

Detailed Explanation of Access Preparation

– Advantages: - Restoration is maintained in its place, so esthetics will be minimally changed - Facilitates rubber dam placement; so isolation is easier - Occlusion is preserved - Cost and time involved in replacement of restoration is saved. – Disadvantages: - Reduced visibility and accessibility - More chances of errors during procedure - Some findings such as extent of caries, vertical fracture of tooth or a hidden canal may be missed. It is generally recommended to remove the existing restoration so that the morphology of tooth is better viewed, radiographic information of coronal part of tooth is obtained and accessibility is improved.

• Gaining access through the restoration (Crown or Bridge) – For access through metal, carbide fissure burs are used – For access through porcelain fused to metal (PFM) crowns: - Round diamond bur to cut through porcelain - Transmetal bur for metal substructure – Copious water coolant spray and use of diamond burs are recommended during access through porcelain to minimize occurrence of microfractures

• Coronal disassembly: Retreatment access is called coronal disassembly as it mostly requires removal of full coverage restoration or a restoration supported by post and core, etc. If there is defect or caries associated with the existing restoration or if the treatment plan calls for a new crown, the old crown is removed and replaced later. Different devices have been manufactured for conser­vative removal of crown without damaging the internal tooth structure. Sometimes reuse of these restorations is possible.

– Canal gets slightly over-enlarged in an attempt to remove all the residue of previous treatment such as sealer and filling material from canal walls as bacteria can hide behind the sealer. – Since primary treatment fails mostly due to infection, one has to be extra careful with asepsis and extra vigorous with antimicrobial treatment. – Liberal use of sodium hypochlorite is recommended. Also other intracanal irrigants like 2% chlorhexidine, final rinse with 17% EDTA to remove the smear layer. – Intracanal medicament like calcium hydroxide may be helpful as an interappointment medicament. • Obturation: Using any of the routinely followed methods. • Post-Endodontic restoration: Coronal restoration as soon as possible to develop good coronal seal followed by full coverage restoration.

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But, most of the times, the restorations need to be sacrificed. • Regaining access to apical area.

Removal of Posts Techniques Removal by reducing retention

Removal by pulling the post from its preparation

Step 1: Expose the post by removal of adjacent restorative materials. Step 2: Small to medium sized ultrasonic tip is inserted at the interface between the post and the tooth and then it is constantly moved around the circumference of the post to disrupt the cement along the post and canal wall interface. This decreases the post retention and facilitates its removal. Thus, judicious use of the ultrasonic instrument in conjunction with a solvent can loosen the post and post may actually spin out of the preparation.

If post cannot be removed by reducing its retention, then post can be pulled out using one of the post removal kits such as: •  The Thomas screw post removal kit for removal of active or screw posts • The Ruddle post removal system for removal of parallel or tapered passive posts • JS post extractor • Post puller or Eggler post remover

Ruddle Post Removal System • The post removal system (PRS) kit is a device intended to be used when the removal of posts with ultrasonics is unsuccessful. • The PRS kit can mechanically engage any obstruction whose cross-sectional diameter is 0.60 mm or greater. • The PRS kit contains an extracting plier, a transmetal bur, five trephines of varying internal diameters, five corresponding tubular taps whose internal diameters range from 0.60–1.60 mm, a torque bar, tube spacers, and a selection of rubber bumpers of varying diameters to properly cushion and protect the tooth during the loads generated by extracting forces. Figure 22.4 shows the photograph of Ruddle post system.

Fig. 22.4  Post removal system (PRS) KIT (Courtesy of Dr Clifford J Ruddle, Advanced Endodontics)

post. The post removal extracting plier is then mounted onto the tubular tap and the jaws of the plier opened by turning the screw knob clockwise (CW). As the jaws open, the tooth is visually inspected to assure, it is cushioned and protected. Increasing pressure will be noted when turning the screw knob, and ultimately this action will serve to remove virtually any post. Tooth-colored posts fabricated from ceramic, zirconium or fiber-reinforced posts are difficult to remove. Ceramic and zirconium posts are usually impossible to retrieve as they are more fragile than metal posts.

Removal of Root Canal Filling

Technique

Silver Point Removal

The largest trephine that will not go over the head of the exposed post is selected. The PRS’s latch-type trephines should rotate at approximately 15,000 rpm in a clockwise (CW) direction in a slow speed, high torque handpiece and, with lubricants, are utilized to machine down a 2–3  mm length of the most coronal aspect of the post. An appropriately sized rubber bumper(s) is inserted onto the selected tubular tap. The tap is manually turned counterclockwise (CCW) to form threads and actively engage the

Step 1: Carefully remove the core material in which the silver point might be embedded. Step 2: Flood the access preparation with a solvent such as chloroform in order to soften or dissolve the cement. Step 3: Grasp the exposed end of the silver point with a Stieglitz pliers or other appropriate forceps and pull it out with a gentle force. Ultrasonics can be employed to facilitate removal of silver points.

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Caufield Silver point retrievers are available in cases where there is not much of silver point exposed in the chamber. Also, Hedstrom files can be used to remove silver point. Two to three Hedstrom files are negotiated as far apically as possible in two or three areas around the silver point. The files are then twisted together and pulled out through the access. Trephine burs may also be used. End-cutting trephine bur is used to remove tooth structure around the point and then an extraction device such as Endo Extractor, Masserann kit, etc. can be used to remove the point.

Gutta-percha Removal Techniques Fig. 22.5  Photograph showing the rotary Endodontic retreatment files–D1, D2, D3 in this order used for removal of GP root canal filling. (Courtesy of Dentsply)

Rotary Endodontic instruments can be used to remove Gutta-percha and sealer while thermoplasticizing the root filling mass using frictional heat to remove it. Combination of solvents along with Hedstrom file and rotary files can be used for safe removal of old Gutta-percha from root canals. Solid core canal obturation systems such as Thermafil, Dens-Fil and the GT® obturator that use a plastic or metal carrier within the mass of Gutta-percha are very difficult to remove from the canal. It is removed by initial use of heat application to carrier that can soften the Gutta-percha surrounding it. Then this carrier is grasped with a forcep.

Pastes and Cement Removal Gutta-percha from coronal 1/3rd of canal is removed using gates glidden drills or Peeso drills. Rotary file systems such as Profile canal finder GPX, Heroshaper R Endo Kit are available to remove entire length Gutta-percha from the canal. Figure 22.5 shows photograph of commercially available rotary files of Endo-Retreatment Kit—D1 D2 D3 in this order having one, two and three rings respectively on their shaft. D1 D2 and D3 are used at the speed of 500 to 700 rpm. D1 has cutting surface blade of 16 mm, 11 mm handle, one white ring and a taper of 9%. D2 has cutting surface blade of 18 mm, 11 mm handle, two white rings and a taper of 8%. D3 has cutting surface blade of 22 mm, 11 mm handle, three white rings and a taper of 7%. D1, D2 and D3 are used in coronal, middle and apical thirds of the root canal, respectively. They are used in this order to remove Gutta-percha from the canal.

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Removal of Canal Obstructions Such as Separated Instruments • Removal depends on location of instrument. – If clinically visible in the coronal access, it can be grasped with a hemostat or Stieglitz pliers and pulled out. – If the instrument is present in the middle 1/3rd of canal, retrieval should be attempted or bypass it. Hand instruments like reamers and files can be used to bypass the separated instrument by inserting alongside the separated instrument to soften its cementation and thus facilitating its removal. Copious irrigation with Sodium hypochlorite (NaOCl), Hydrogen peroxide (H2O2)may float the object coronally through the effervescence created. – If the instrument lies in the apical 1/3rd of canal, it is left behind or the case is surgically treated. The decision to retrieve the broken instrument is based on evaluation as to how much tooth structure will have to be removed to gain access to the instrument. – In order to remove separated root canal instruments, straight-line coronal-radicular access has to be created with the use of modified Gates-Glidden drills. GG drills are modified by sectioning with a bur at their maximum cross-sectional diameter to create a circumferential staging platform to facilitate ultrasonic use. The vibration caused by ultrasonics placed on the platform between exposed end of file and the canal wall helps in removal of that broken file. There are many techniques and devices now available to facilitate removal of separated instrument. Many kits have been introduced such as the Endo extractor, the Masserann kit, the Extractor system and the Instrument Removal System and the Separated Instrument Retrieval system (SIR). One of the Ruddle’s inventions: File removal system is described here. Figure 22.6 shows the photograph of the file removal system. • In cases, where ultrasonic trephining procedures are limited or prove ineffective, the File Removal System (FRS) may be utilized to mechanically engage and potentially remove intracanal obstructions, such as silver points, carrier-based obturators or broken file segments. • The instrument with the black handle is used to work in the coronal one-third of larger canals, whereas the

Fig. 22.6  File removal system (Courtesy of Dr Clifford J Ruddle, Advanced Endodontics®)

red and yellow instruments can be placed progressively deeper into smaller, more narrow canals. • Each complete instrument is comprised of a color coordinated microtube and screw wedge. First trephination is carried out using Ultrasonics, then position the microtube and it is used to engage and remove the obstruction.

WHAT IS THE PROGNOSIS OF ENDODONTIC RETREATMENT? • In absence of prior apical periodontitis, the percentage of healed cases after both initial treatment and nonsurgical retreatment has been found to be about 92–98%. • In presence of prior apical periodontitis, the percentage of healed cases has been found to be 74–86% regardless of whether initial treatment or nonsurgical retreatment was performed. A tooth that has persistent apical periodontitis may remain in asymptomatic function for an extended period, this state is referred to as functional retention of tooth.

BIBLIOGRAPHY 1. Cohen S, Hargreaves KM. Pathways of Pulp, 9th edn. St. Louis: Mosby, 2006.pp.944-1005. 2. http://www.endoruddle.com/inventions.html 3. Ingle J, Bakland L, Baumgartner J. Ingle’s Endodontics 6, 6th edn. BC Decker Inc, Hamilton, 2008.pp.1088-217.

CHAPTER

23

Management of Discolored Teeth

This chapter describes about tooth discoloration and explains in detail about ‘bleaching’, as a treatment modality for whitening of vital and Endodontically treated teeth.   You must know • What are the Causes of Tooth Discoloration? • What are the Different Methods of Management of Discolored Teeth? • What is Bleaching of Teeth? • Why Bleaching? • What is the Chemistry and Mechanism of Bleaching? • Etiology of Tooth Discoloration and its Management in Detail • What are the Indications and Contraindications of Bleaching? • Which are the Materials Used for Bleaching? • What is the Technique for Bleaching Vital Teeth? • What are the Side Effects and Adverse Effects of Extracoronal Bleaching of Vital Teeth? • What is the Technique for Bleaching Endodontically-Treated Teeth? • What are the Side Effects and Adverse Effects of Intracoronal Bleaching of Endodontically Treated Teeth? • How do we Restore Intracoronally Bleached Endodontically Treated Tooth? • What is Enamel Microabrasion? • What is the Role of Veneers and Crowns in Management of Discolored Teeth?

INTRODUCTION Color is an important characteristic of teeth. • The normal color of primary teeth is bluish white. • The normal color of permanent teeth is grayish yellow, grayish white or yellowish white. The color of the teeth is due to: • Translucency and thickness of enamel

• Thickness and color of the underlying dentin • Color of the pulp.

WHAT ARE THE CAUSES OF TOOTH DISCOLORATION? Any change in the hue, color or translucency of a tooth is referred to as tooth discoloration. Etiology of tooth discoloration can be classified in following 2 ways:

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Out of all the causes listed in the given two classifications, decomposition of pulp tissue is the most common cause of tooth discoloration particularly when the pulp is necrotic. Several months after necrosis of the pulp or treatment of tooth, discoloration is noticed due to slow formation of color producing compounds. Traumatic injury is the next common cause of tooth discoloration. Due to trauma, there is rupture of blood vessels in the pulp and diffusion of blood into dentinal tubules. Immediately after accident, such a tooth may have a dark pinkish hue and some days later it may turn pinkish brown. The etiology of tooth discoloration along with its management is described in detail later in this chapter.

WHAT ARE THE DIFFERENT METHODS OF MANAGEMENT OF DISCOLORED TEETH? Depending on the extent of discoloration and other factors, different methods of management of discolored teeth include: • Teeth bleaching • Enamel microabrasion • Restorative options: – Composite veneers/restoration – Ceramic veneers/laminates – Crowns.

WHAT IS BLEACHING OF TEETH? Bleaching of teeth is a treatment modality which makes use of an oxidizing agent that is capable of bringing about the alteration in the light-absorbing and/or light-reflecting nature of a material structure, thereby increasing its perception of whiteness. Hence, bleaching of teeth is also referred to as teeth whitening.

WHY BLEACHING? • Yellowish looking teeth can be whitened by means of bleaching. Discoloration of teeth can occur due to various endogenous or exogenous causes as listed above in the Etiology of tooth discoloration. • Discolored teeth can be whitened by means of bleaching. Thus, the goal of bleaching procedure is to restore tooth esthetics by restoring the normal color of the tooth.

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WHAT IS THE CHEMISTRY AND MECHANISM OF BLEACHING? Redox reaction: The bleaching process involves oxidation of the bleaching agent. The oxidation-reduction reaction that takes place in the bleaching process is called the redox reaction.

ETIOLOGY OF TOOTH DISCOLORATION AND ITS MANAGEMENT IN DETAIL Patient-related Causes Extrinsic Stains Stains from foods, beverages, tobacco products and chemicals from mouth rinses, toothpowders, etc. are all of local origin and can be removed by scaling and polishing.



Intrinsic Stains • Pre-eruptive causes: Several systemic conditions may result in discoloration of teeth. a. Diseases: Several systemic conditions may result in discoloration of teeth. Systemic condition

Tooth discoloration

•  Alkaptonuria

• Dark brown pigmentation of primary teeth

•  Thalassemia, sickel cell anemia

• Blue, brown or green discoloration

•  Erythroblastosis fetalis

• Results in lysis of erythrocytes and hemosiderin gets incorporated in the forming dentin. Green, brown or bluish stain

•  Porphyria

• Reddish or brownish discoloration of deciduous and permanent teeth

•  Amelogenesis imperfecta (AI)

•  Yellow or brown discoloration

•  Dentinogenesis imperfecta (DI)

• Brownish violet, yellowish or gray discoloration



Fig. 23.1  Photograph showing generalized discoloration of teeth due to tetracycline (Courtesy of Dr CR Suvarna)

Stains due to the conditions such as amelogenesis imperfecta (AI), dentinogenesis imperfecta (DI) are usually not possible to eliminate by bleaching as they originate from developmental defects of enamel and dentin. Correction by restorative means is preferred. b. Medications: Ingestion of certain drugs during tooth formation may cause severe discoloration in both enamel and dentin. Figure 23.1 shows generalized discoloration of teeth due to tetracycline.

According to severity, tetracycline discoloration can be classified as: • First degree: Light yellow, light brown or light gray uniform discoloration throughout the crown. No banding. • Second degree: More intense discoloration. No banding. • Third degree: Very intense discoloration; horizontal color banding seen; cervical region of teeth is mostly affected. Tetracycline discoloration usually occurs bilaterally affecting multiple teeth in both arches. Severity of stains depends on time and duration of drug administration, type of tetracycline and dosage. Role of bleaching in case of tetracycline-stained teeth: • Mild to certain moderate cases (First and second degree). Repeated external bleaching for an extended period. They may respond well to three or four bleaching sessions. • Severe cases (Third degree)—May not be amenable to bleaching. Restorative means will be required. c. Fluorosis: Excessive exposure to fluoride during tooth formation can result in dental fluorosis or mottled enamel. Such teeth are not discolored on eruption, but their porous surface attracts extrinsic stains. Intermittent white spots, chalky or opaque areas, yellow or brown discoloration is seen. Severe cases present as surface pitting of enamel. Role of bleaching: External bleaching may be effective for mild-to-moderate dental fluorosis. Restorative procedure for severe dental fluorosis.

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• Posteruptive causes a. Pulp necrosis: Most common cause of tooth discoloration.



Several months after death of the pulp or treatment of tooth, discoloration is noticed due to slow formation of color producing compounds. Figures 23.2A to  C show the photographs of discolored upper right central incisor due to trauma causing pulp necrosis. Photographs are taken in three different positions. Role of bleaching: Intracoronal bleaching is effective in these cases. b. Intrapulpal hemorrhage:



If pulp recovers, discoloration may be reversed. If pulp becomes necrotic, discoloration persists and becomes severe with time. Figure 23.3 shows photograph of discolored maxillary central incisor tooth. Role of bleaching: Intracoronal bleaching is effective in these cases. c. Aging: Due to aging, there is decrease in thickness of enamel due to wasting diseases of teeth — attrition, abrasion, erosion. On the other hand, there is increase in the thickness of dentin and changes in optical properties of tooth due to deposition of secondary and reparative dentin. So, the yellow color of dentin becomes more apparent in older teeth as shown in Figure 23.4. Extrinsic stains are removed by scaling and polishing and then extracoronal bleaching can be done to restore white color of the teeth. d. Calcific metamorphosis: Deposition of hard tissue within the root canal space in response to trauma is called calcific metamorphosis.

A

B

C Figs 23.2A to C  Photograph showing discolored upper right central incisor due to trauma causing pulp necrosis. Photograph taken in three different positions (Courtesy of Dr CR Suvarna)

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Fig. 23.3  Photograph showing discolored maxillary right central incisor (Courtesy of Dr CR Suvarna)

Fig. 23.5  Photograph showing discoloration of first premolar due to old silver amalgam restoration (Courtesy of Dr CR Suvarna)

A

B

Figs 23.6A and B  Photograph showing discolored composite restorations: (A) Maxillary lateral incisor; (B) Mandibular first molar (Courtesy of Dr CR Suvarna) Fig. 23.4  Photograph showing yellowish discoloration of teeth due to wasting diseases (Courtesy of Dr CR Suvarna)



Such teeth appear yellowish or yellowish-brown. To correct such discoloration, root canal treatment should be done first and it is followed by intracoronal bleaching.

Dentist-related Causes Related to Coronal Restorations • Metallic restorations: Such as silver amalgam restorations degrade over time and corrosion products can cause

tooth discoloration. Figure 23.5 shows blackish discoloration of first premolar tooth due to old silver amalgam restoration Role of bleaching: Such a discoloration is difficult to bleach. Replacing amalgam restoration with tooth colored restoration can sometimes solve the problem. • Composite resin restorations: These restorations become discolored over a period of time. Microleakage around the restoration can discolor the underlying dentin. Figures 23.6A and B show discolored composite restoration. Replacing old composite restoration with a new, wellsealed composite restoration can solve the problem.

Management of Discolored Teeth

Related to Endodontic Treatment • Remnants of pulp tissue: Inadequate access cavity preparation which has not included the pulp horns, especially in anterior teeth, result in discoloration of Endodontically treated tooth due to pulp tissue remnants that are left behind. Intracoronal bleaching is effective in such cases. • Intracanal medicaments: Such as phenols or iodoformbased medicaments sometimes may cause their penetration into surrounding dentin. Oxidation occurs resulting in discoloration. Intracoronal bleaching may be effective.

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• Obturating materials: If the obturating material and sealer remnants remain in the pulp chamber of Endodontically treated tooth, discoloration can occur. To correct such a discoloration, the remnants of obturating material are first removed and the intracoronal bleaching is done. To prevent this kind of discoloration, the obturating materials and sealer remnants must be removed just below the level of the gingival margin before the final restoration is done. A mind-map to remember etiology of tooth discoloration is given in Figure 23.7.

Fig. 23.7  A mind-map to remember all points of etiology of tooth discoloration

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WHAT ARE THE INDICATIONS AND CONTRAINDICATIONS OF BLEACHING?

• Superoxol is a 30% solution of hydrogen peroxide by weight and 100% by volume in pure distilled water. It decomposes readily in an open container, so it has to be stored in sealed refrigerated containers. • Hydrogen peroxide in high concentrations has ischemic effect on skin and mucous membrane. So, these materials should be carefully handled to avoid their contact with tissues during handling and bleaching treatment. Figure 23.8 shows photograph of commercially available 35% hydrogen peroxide for bleaching. Carbamide peroxide: • Carbamide peroxide is in the form of crystallized powder that contains 35% hydrogen peroxide. • It is called urea hydrogen peroxide and yields urea and hydrogen peroxide on decomposition. • Carbamide peroxide in the concentration of 10–30% is used for at-home bleaching, 10% being the most common. • Carbamide peroxide in the concentration of 35% may be used for in-office bleaching. Carbopol: Some bleaching preparations contain a water soluble polyacrylic acid polymer called carbopol. Carbopol is added as a thickening agent. Carbopol prolongs the release of active peroxide. Thus, it improves the shelf life of the bleaching preparation.

WHICH ARE THE MATERIALS USED FOR BLEACHING? Bleaching is based on peroxide compounds as the active agent. It acts as an oxidizing agent and there is formation of free radicals and reactive oxygen molecules that attack the long chained dark colored molecules and split them into smaller, less colored and more diffusible molecules. For extracoronal bleaching: Hydrogen peroxide, carbamide peroxide are used. For intracoronal bleaching: Sodium perborate and superoxol are used. Hydrogen peroxide: • Hydrogen peroxide is a strong oxidizing agent, which may be applied directly or be produced in a chemical reaction from carbamide peroxide or sodium perborate. Decomposition of carbamide peroxide and sodium perborate releases hydrogen peroxide in an aqueous medium. • It is used in both in-office and at-home bleaching materials. In-office bleaching materials have 25–38% concentration of H2O2. At home, bleaching materials have 3–7.5% concentration of H2O2.

Sodium perborate: • Sodium perborate is available as a white powder containing about 95% perborate, corresponding to 9.9% of the available oxygen.

Fig. 23.8  Commercially available 35% hydrogen peroxide for bleaching (Courtesy of Mr Amar, Dr Dabholkar’s clinic)

Management of Discolored Teeth

• It is stable when dry but when exposed to acid, warm air or water, sodium perborate decomposes to form sodium metaborate, hydrogen peroxide, and nascent oxygen. • Depending on oxygen content, sodium perborate is available as monohydrate, trihydrate and tetrahydrate. The oxygen content determines the bleaching efficacy. • Sodium perborate is safer for use as compared to hydrogen peroxide for bleaching. It may be mixed with superoxol (30% H2O2 by weight) to form a paste that decomposes into sodium metaborate, water and oxygen. • Sodium perborate is the material of choice for intracoronal bleaching, in which it is sealed into the pulp chamber where it oxidizes and discolors the stain slowly over a period of time, the technique commonly referred to as walking bleach technique.

WHAT IS THE TECHNIQUE FOR BLEACHING VITAL TEETH?

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• Indications: Figure 23.9 gives the indications for extracoronal bleaching of teeth. • Types: Extracoronal bleaching for vital teeth can be carried out: – By clinician in the dental clinic; in-office extracoronal bleaching/chair-side bleaching/power bleaching – By patient at home, under the guidance and supervision by dentist ; at-home extracoronal bleaching. I. Technique for in-office extracoronal bleaching of vital teeth: – Bleaching materials: - 25–38% H 2 O 2 (35% H 2 O 2 commonly used) available in gel form is used. - Carbamide peroxide gel (10%, 15%, 20%, 35%) – Mode of bleaching: - Bleaching gel applied alone, or - Bleaching gel in combination with light source

Extracoronal bleaching is done for vital teeth.

Fig. 23.9  Indications of extracoronal bleaching of vital teeth

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- Earlier, heat, electric current and other chemicals were applied with bleaching gel to enhance its bleaching efficacy. They are rarely used now. Light used: Regular curing light for resin composites • Light-emitting diodes (LED) • Laser light (e.g. Argon, CO2): Less popular • Specialized light for bleaching – Clinical procedure: - First step is to record the pretreatment color of teeth (shade) using a camera (Photograph). This provides an excellent baseline data. - Diagnostic testing: Clinical and radiographic examination of all teeth for any possible caries, defective restorations, periapical or pathologic condition which should be treated prior to bleaching. - Cleaning: Thorough scaling and prophylaxis is a must. Prophy-jet prophylaxis will free the teeth to be bleached of all surface stains and plaque. - Isolation: Isolating the teeth to be bleached and protection of gingiva and other soft tissues of the mouth using a rubber dam, waxed dental floss, reflective resin barrier, orabase, etc. - Protection of patient and dental team: Surgical rubber gloves and safety glasses for the dental staff. Heavy plastic wrap for patient’s hands and clothes. Safety glasses for the patient. - Bleaching proper: ■ Rinse and remove excess varnish, jelly or orabase from enamel of the teeth to be bleached with pumice and water ■ Etch each tooth facially and lingually for 20  seconds with 37% phosphoric acid ■ Rinse for 30 seconds and dry the teeth ■ Apply bleaching agent: Superoxol or 35% hydrogen peroxide with a piece of cotton gauze, adhesive strips, paint-on or trays ■ Careful handling of bleaching material and high vacuum suction is used ■ Position the bleaching light with an adjusted rheostat setting. Bleaching temperature recommended for vital teeth is 115˚C. - After bleaching procedure, remove gauze and flush teeth with copious amounts of warm water before carefully removing floss and rubber dam. - Polish the teeth with polishing wheels. Since the enamel is demineralized during bleaching

it tends to absorb extrinsic stains faster from foods, beverages, etc. So, polishing of teeth after in-office bleaching is an essential step. II. Technique for at-home extracoronal bleaching of vital teeth: – Bleaching materials: Hydrogen peroxide and carbamide peroxide are used as active ingredients for professional at-home bleaching procedure. Concentration is 3–7.5% H2O2 or 10–22% carbamide peroxide. – Mode of bleaching: Custom tray is manufactured for the patient. Bleaching gel is to be loaded in the tray and patient wears the tray for several hours in night for few days. Figure 23.10 shows photograph of soft vinyl custom tray fabricated for bleaching. Professional bleaching strip is also available for athome bleaching. Figure 23.11 shows photograph of prefabricated bleaching trays with loaded bleaching material. – Procedure: - Scaling and polishing of teeth and any other restorative treatment required by the patient is performed first. - Upper and lower arch impressions are made.

Fig. 23.10  Soft vinyl custom tray fabricated over the patient’s model. Blue marked areas are to incorporate reservoirs in tray for loading bleaching material (Spacer) (Courtesy of Dr Mahashabde, Rajesh Shivhare’s clinic)

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followed. In spite of all these, adverse effects can occur depending on the individual’s response to bleaching treatment, such as:

Postbleach Sensitivity of Teeth Mild to moderate sensitivity of teeth can occur lasting for 2–3 days. Higher incidence of sensitivity has been found after in-office bleaching in which H2O2 was used in combination with heat.

Fig. 23.11  Prefabricated bleaching trays with loaded bleaching material is also available commercially (Courtesy of Dr Mahashabde, Dr Rajesh Shivhare’s clinic)

- Models are sent to the laboratory for manufacture of custom-made trays. More attention is paid to the tray design. Trays are constructed with periphery barely shy of gingival line (approx. 1/4–1/3 mm). Scalloping around the interdental papilla is to be provided in the tray. - Trays are made of soft vinyl tray material. Reservoirs are incorporated in the trays using block-out or adhesive strips as shown in Figure 23.10. - Bleaching material is dispensed to patients in unit dose syringes, assuring dentist supervision. - Clinician gives instructions to the patient regarding how to carefully insert, handle and store the tray and about the special precautions to be taken. - As per the type of bleaching material and its application technique, the clinician must follow manufacturer’s instructions to give advice to the patient for at-home bleaching.

WHAT ARE THE SIDE EFFECTS AND ADVERSE EFFECTS OF EXTRACORONAL BLEACHING OF VITAL TEETH? Bleaching of vital teeth is a relatively safe procedure, if carefully done and all precautions taken and instructions

Management: Postbleach sensitivity can be managed by: • Topical fluoride application such as 0.5% fluoride ion gel • Desensitizing toothpastes containing 3% potassium nitrate. Precautions: • Do not perform bleaching on teeth with caries, exposed dentin or teeth with reduced enamel and dentin thickness and close proximity to pulp. • Defective restorations must be replaced prior to bleaching. • If sensitivity is noticed, shorter bleaching periods are recommended for such patient.

Effects on Enamel • Decrease in enamel surface microhardness. • Increased porosity and slight erosion of enamel may be seen. Postbleach application of fluoride to the surface of enamel may be useful.

Gingival Irritation Mild-to-moderate gingival irritation may occur for 2–3 days after bleaching. Tissue burn can occur. Causes: • Ill-fitting bleaching tray • Increased concentration of hydrogen peroxide • Contact of bleaching gel to the gingiva • Leaky gingival barrier protection. Management: In case of tissue burn, rinse the tissue surface thoroughly with water. Topical anesthetic may be applied. Precautions: • Use of protective creams such as vaseline, orabase, cocoa butter • Well-made bleaching tray • Proper gingival barrier protection.

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Effect on Restorations • Silver amalgam restorations : During and after extracoronal bleaching, release of mercury has been reported from the restorations. Avoid extracoronal bleaching for teeth with extensive amalgam restorations. • Composite resin restorations: Bleaching may not have effect on the color of the restoration. Increase in microleakage has been found. Some roughening of the surface of the restoration has been reported. A mind-map to remember side effects/adverse effects of extracoronal bleaching of vital teeth is given in Figure 23.12.

• Methods: – Walking bleach technique – Thermocatalytic technique (Heat) – Use of ultraviolet photo-oxidation (Light) • Bleaching agents: – Superoxol: 30% solution of hydrogen peroxide by weight and 100% by volume in pure distilled water – Sodium perborate: White crystalline odorless compound which has an oxidizing effect due to its hydrogen peroxide component – 35% hydrogen peroxide – 5–7% sodium hypochlorite.

WHAT IS THE TECHNIQUE FOR BLEACHING ENDODONTICALLY-TREATED TEETH?

Walking Bleach Technique

• Intracoronal bleaching is generally done for Endodontically treated teeth.

Sodium perborate is mixed into a paste with superoxol. This paste decomposes into sodium metaborate, water and

Fig. 23.12  A mind-map to remember all points of side effects/adverse effects of extracoronal bleaching of vital teeth

Management of Discolored Teeth

oxygen. When sealed into the pulp chamber, it begins to oxidize and discolor the stain slowly and gradually over a period of time. This procedure is referred to as walking bleach. It basically refers to the bleaching action occurring between patients’ visits. • Step-by-step clinical procedure: – Assessment of quality of Endodontic treatment: The Endodontically treated tooth should be evaluated radiographically to assess the quality of obturation, and for any signs of periapical pathosis. Endodontic failure cases will have to be retreated prior to bleaching. – If postobturation coronal restoration is defective, then replace it. – Record the pretreatment color of the tooth (shade) using a camera (photograph) to provide the baseline data. – Polish the enamel surface with a prophylaxis paste to remove any gross surface debris or discolorations. – Apply protective cream such as vaseline, orabase to the gingival tissues around the tooth to be bleached. – Isolate the tooth using rubber dam that fits tightly at the cervical margin of the tooth to be bleached. – Re-establish the access cavity: Lingual opening of sufficient size is made in case of anterior teeth. Remove: - All restorative materials from the access cavity. - Any gutta-percha root canal filling extending into the pulp chamber Refine the access, exposing the dentin. – Examine the pulp chamber and see to it that the pulp horns and other areas containing the pulp tissue are clean. – Remove the gutta-percha root canal filling up to the level of crest of alveolar bone, that is up to a depth of 2–3 mm apical to the cervical line in order to confine the bleaching agents to the crown of the tooth as shown in Figures 23.13A. – Seal the orifice of the root canal with a sufficiently thick layer of atleast 2 mm of a protective white cement barrier, such as zinc phosphate, polycarboxylate cement or glass ionomer cement coronally to the level of CEJ to cover the Endodontic obturation as shown in Figure 23.13B. – Apply 25% solution of citric acid or 30% solution of orthophosphoric acid to the dentinal surface of the pulp chamber. The acid can be removed by flushing with sodium hypochlorite or water. Air dry the tooth. Now, it has been found that acid etching is not desirable as use of such chemicals can cause irritation to periodontal ligament.

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Figs 23.13A to C  (A) Diagram showing the level to which guttapercha needs be removed below the cervical line, i.e. at the level of alveolar crest shown by dotted line; (B) Diagram showing 2 mm cement barrier; (C) Diagram showing bleaching agent placed in cavity and the cavity sealed with an intermediate restorative material

– Prepare the walking bleach paste by mixing sodium perborate powder with superoxol to a thick paste in a clean dappen dish to have consistency of wet sand. – With a plastic instrument, pack the paste into pulp chamber. – Place a cotton pellet over the bleaching paste to remove any excess liquid and to compress and push the paste into all areas of the pulp chamber. – Seal the access cavity with IRM (Intermediate restorative material) or any thick well-sealed temporary filling of thickness about 3 mm to ensure a good seal as shown in Figure 23.13C. Hold the restoration with digital pressure for few seconds to a minute after it is placed, otherwise it tends to come out due to the pressure caused by the bleaching agent due to its chemical reaction. Figures 23.14A to J show photographs of a clinical case where bleaching was done for management of discolored maxillary right central incisor and mandibular left central incisor. Both the teeth were Endodontically treated. Internal bleaching was done for both. Mandibular left central incisor responded well while maxillary right central incisor was taking a little time especially the proximal area. In-office external bleach was also done followed by home bleach to achieve a good result.

Walking Bleach Result Significant lightening is attained about 24 hours after treatment. Evaluate the patient one week later and if necessary, repeat the procedure several times.

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Fig. 23.14A  Discolored maxillary right central incisor and mandibular left central incisor—Labial view (Courtesy of Dr CR Suvarna)

Fig. 23.14B  Discolored maxillary right central incisor—Labial and palatal view (Courtesy of Dr CR Suvarna)

Fig. 23.14C  Discolored mandibular left central incisor—Labial and lingual view (Courtesy of Dr CR Suvarna)

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Fig. 23.14D  Postobturation radiographs of maxillary right and mandibular left incisor teeth respectively (Courtesy of Dr CR Suvarna)

Fig. 23.14E  Coronal seal achieved with glass ionomer cement after placement of bleaching material (Courtesy of Dr CR Suvarna)

Fig. 23.14F  Results of intracoronal bleaching of maxillary right central incisor and mandibular left central incisor (Courtesy of Dr CR Suvarna)

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Fig. 23.14G  Extracoronal bleaching of maxillary and mandibular anterior teeth (Courtesy of Dr CR Suvarna)

Fig. 23.14H  Result of intracoronal followed by extracoronal bleaching (labial view) (Courtesy of Dr CR Suvarna)

Fig. 23.14I  Coronal seal achieved with composite restoration in both teeth (Courtesy of Dr CR Suvarna)

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Fig. 23.14J  Preoperative and postoperative (Courtesy of Dr CR Suvarna)

About 2–3 treatments, performed a week apart, should suffice. If not, then reassess the case for correct diagnosis of etiology of discoloration. Walking bleach is the method of choice for bleaching Endodontically treated teeth because: • It is easy to perform • Consumes less chairside time • More comfortable to patient • Requires no special equipment • Safe technique.

Thermocatalytic Bleaching • This technique involves placing superoxol matted cotton pellets into the pulp chamber. The solution is activated by heat application either by electric heating devices or specially designed lamps. • Intermittent 5–6 minutes exposures of the tooth with heat and in-between cooling breaks, is done. • Care must be taken to protect the teeth and surrounding tissues from overheating. Protective creams such as vaseline, orabase, cocoa butter can be applied to the soft tissues during treatment to avoid heat damage. • Application of high concentration of H2O2 in combination with heat can cause irritation to the cementum and periodontal ligament of the tooth being bleached causing external cervical root resorption. • Clinical result with this technique does not appear to differ. So, the thermocatalytic approach is not used routinely.

Use of Ultraviolet Photo-oxidation • This technique involves placing superoxol matted cotton pellet into the pulp chamber followed by 2-minute exposure to ultraviolet light. • Bleaching result does not differ. • Not carried out routinely.

WHAT ARE THE SIDE EFFECTS AND ADVERSE EFFECTS OF INTRACORONAL BLEACHING OF ENDODONTICALLY TREATED TEETH? External Cervical Root Resorption High concentration oxidizing agent (30–35% H2O2) may diffuse through exposed dentinal tubules and cementum defects ↓ Necrosis of cementum ↓ Inflammation of periodontal ligament ↓ Root resorption Prevention: Effective isolation of tooth with rubber dam, interproximal wedges and ligatures. Management: Use of calcium hydroxide dressing for a week, in the access cavity prepared.

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Gingival Irritation and Tissue Burns If superoxol comes in contact with the gingival tissue, it can cause chemical burns and sloughing of gingiva. Prevention: • Protective creams such as vaseline, orabase, cocoa butter to be applied to the soft tissues around the tooth to be bleached. • Use gingival barrier. Most of the commercially available bleaching kits contain a gingival barrier which is lightcured, so that the bleaching material does not leak through to reach gingiva. For example, Pola office.

Reduction in Bonding Strength of Composite Resin Restorations After bleaching, if residual H 2O2 remains in the tooth structure, the oxygen tends to: • Inhibit resin polymerization • There is decrease in bonding strength of resin composites to enamel and dentin. • There is increase in resin porosity. Prevention: Residual H2O2 should be totally eliminated prior to composite resin placement, which means composite restoration placement should be delayed for 7–10 days.

Postbleaching Inflammation of Periodontal Ligament Improper barrier over the coronal extent of root canal filling causes: Leakage of bleaching agents through the space between gutta-percha filling and root canal walls ↓ Leakage products reaching the periodontal ligament via dentinal tubules, root apex, lateral and accessory canals ↓ Inflammation of PDL

This can further lead to root resorption.

Prevention: Adequate cement barrier of thickness of atleast 2 mm over the coronal extent of root canal filling. The ideal barrier is the one that protects the dentinal tubules and conforms to the external epithelial attachment. A mind-map to remember all points of side effects/ adverse effects of intracoronal bleaching of teeth is given in Figure 23.15.

HOW DO WE RESTORE INTRACORONALLY BLEACHED ENDODONTICALLY TREATED TOOTH? • Any residual H2O2 from bleaching in the tooth structure adversely affects the bond strength of composites with enamel and dentin. Therefore, it is recommended that one should wait for at least 7 days after bleaching, prior to restoring the tooth with composite restorations. • It is recommended that a white cement be placed beneath the composite restoration that helps in distinguishing between composite and tooth structure during rebleaching. • Permanent coronal seal with composite resin restoration after bleaching is to be done otherwise rediscoloration of tooth would occur, if there is leaking restoration. A mind-map to remember all points of bleaching is given in Figure 23.16.

WHAT IS ENAMEL MICROABRASION? • Enamel microabrasion involves decalcification and removal of a thin layer of stained enamel. • Enamel microabrasion technique is also called “Controlled hydrochloric acid-pumice abrasion” technique. • This technique is mainly useful for fluorosis and also for other extrinsic discolorations such as brown, orange or yellow enamel spots and streaks, regardless of etiology provided the stain is limited to a thin layer of tooth surface (about 0.5 mm) • Enamel abrasion procedure can be used independently or prior to bleaching in certain cases. • Step-wise procedure: – Record the shade of the teeth. Take pretreatment photographs – Protect the gingiva and carefully isolate the teeth with an inverted rubber dam and ligatures – 18% hydrochloric acid solution is prepared by mixing 36% hydrochloric acid solution with equal volume of distilled water and adding fine flour of pumice to form a thick paste and is applied to enamel surface using a piece of wooden tongue blade or crushed orangewood stick. The paste is worked into the enamel surface exerting firm pressure with a scrubbing motion for 5 seconds. – Then the enamel surface is rinsed with water for 10 seconds. – A mixture of sodium bicarbonate with water forming a thick paste is applied on the enamel surface for acid neutralization.

Management of Discolored Teeth

Fig. 23.15  A mind-map to remember all points of side effects/adverse effects of intracoronal bleaching of teeth

Fig. 23.16  A mind-map to remember all points of bleaching

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– Remove the rubber dam and use fine prophylactic paste to smoothen the abraded enamel surface. • Safety precautions: – Excessive decalcification may occur. But, careful and judicious application of 18% hydrochloric acid does not usually remove significant amount of enamel. – Chemical burns of soft tissues can be prevented by using protective barriers.

WHAT IS THE ROLE OF VENEERS AND CROWNS IN MANAGEMENT OF DISCOLORED TEETH? Use of Composite Restoration/veneer for Discolored Teeth • If composite is to be used for discolored teeth, an important consideration is masking of dentin shade not only at the facial surface but also at the cervical margins and incisal edges. • The tooth should be prepared to allow a uniform thickness of composite to create a polychromatic appearance in the final result. • If there is severe discoloration, the depth of preparation should allow an additional thin layer of opaque composite to mask the dark dentin. • The incisal edges may need to be covered with composites in few cases extending on the palatal surface.

Use of Ceramic Veneer/Laminates for Discolored Teeth • Ceramic laminates can be used in case of discolored teeth. If the discoloration is mild to moderate, the tooth

preparation can be minimal from 0.3 mm cervically to 0.5 mm at the incisal edge. For severe discoloration, the preparation has to be deeper than this. • When more opaque ceramic is added in the veneer, it masks the undesirable tooth color but that limits the display of vitality. • A more translucent ceramic allows more light transmission and reflection internally, making the restoration more vital.

Full Coverage Metal-ceramic or All-ceramic Crowns for Discolored Teeth • In case of severely discolored tooth or Endodontically treated disclored tooth with considerable loss of tooth structure, metal-ceramic or all-ceramic restorations are indicated. Now-a-days, all-ceramic restorations (metalfree), that make use of Zirconia or Lithium disilicate have become quite popular and are being widely used to give pleasing esthetics, simulating natural appearance. • Intra-coronal bleaching of Endodontically treated discolored tooth followed by all-ceramic restoration gives favorable result.

BIBLIOGRAPHY 1. Grossman L, Oliet S, Del Rio C. Endodontic Practice, 11th edn. Varghese Publication, 1991.pp.271-7. 2. Ingle J, Bakland L, Baumgartner J. Ingle’s Endodontics, 6th edn. BC Decker Inc, Hamilton, 2008.pp.1383-96. 3. Patil R. Esthetic Dentistry: An Artist’s Science. 1st edn. PR Publications, 2002.pp.105-7, 129. 4. Torabinejad M, Walton RE. Endodontics: Principles and Practice, 4th edn. Saunders, an imprint of Elsevier, 2009.pp.402-3.

CHAPTER

24

Management of Dental Traumatic Injuries

This chapter explains the various dental traumatic injuries with their consequences and discusses the various treatment modalities for their management including the considerations at the emergency visit.  • • • • • • •

You must know What are the Unique Aspects of Dental Trauma? What are the Consequences of a Dental Traumatic Injury? How do we Classify Traumatized Teeth? How do we Make Diagnosis in Case of Dental Traumatic Injuries? What are the Factors to be Considered for Treatment of Traumatized Teeth? What are the Different Dental Traumatic Injuries and their Management? Requirements for Success of Vital Pulp Therapy in Case of Traumatized Teeth

WHAT ARE THE UNIQUE ASPECTS OF DENTAL TRAUMA?

WHAT ARE THE CONSEQUENCES OF A DENTAL TRAUMATIC INJURY?

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HOW DO WE CLASSIFY TRAUMATIZED TEETH? • WHO classification has given following code numbers: 873.60 Enamel fracture 873.61 Crown fracture involving enamel and dentin without pulp exposure 873.62 Crown fracture with pulp exposure 873.63 Root fracture 873.64 Crown-root fracture 873.66 Luxation 873.67 Intrusion or extrusion 873.68 Avulsion 873.69 Other injuries, such as soft tissue laceration • Andreasen’s modification of WHO classification: 873.64 Uncomplicated crown-root fracture without pulp exposure 873.64 Complicated crown-root fractures with pulp exposure 873.66 Concussion 873.66 Subluxation 873.66 Lateral luxation • International association of Dental Traumatology uses classification based on WHO and modified by JO Andreasen and FM Andreasen, which is as follows: Soft tissues N873.69 Lacerations N902.0 Contusion N910.0 Abrasions Tooth fractures N873.60 Enamel fracture N873.61 Crown fracture involving enamel and dentin without pulp exposure N873.62 Crown fracture with pulp exposure N873.63 Root fracture 873.64 Crown-root fracture Luxation injuries 873.66 Tooth concussion 873.66 Subluxation 873.66 Extrusive luxation 873.66 Lateral luxation 873.67 Intrusive luxation 873.68 Avulsion Facial skeletal injuries 802.20 Fracture of alveolar process of mandible 802.40 Fracture of alveolar process of maxilla 802.21 Fracture of body of mandible 802.41 Fracture of body of maxilla • Ellis and Davey’s classification: Class I: Simple fracture of crown involving enamel only. Figure 24.1 shows photograph of fractured incisal edges of both central incisors due to trauma.









Class II: Extensive fracture of crown involving enamel and considerable amount of dentin but no pulp exposure. Figure 24.2 shows photograph of fracture of maxillary left central incisor involving enamel and dentin. Class III: Extensive fracture of crown, involving enamel and considerable amount of dentin with pulp exposure. Figure 24.3 shows photograph of fracture of both maxillary central incisors involving enamel, dentin and pulp. Class IV: Traumatized tooth becomes nonvital with or without loss of crown structure. Figure 24.4 shows photograph of traumatized discolored maxillary right central incisor tooth without loss of crown structure. Class V: Tooth lost due to trauma.

Fig. 24.1  Fractured incisal edges of both central incisors due to trauma (Courtesy of Dr Manoj Ramugade)

Fig. 24.2  Trauma to maxillary left central incisor involving enamel and dentin (Courtesy of Dr CR Suvarna)

Management of Dental Traumatic Injuries

Fig. 24.3  Trauma to maxillary central incisors involving enamel, dentin and pulp (Courtesy of Dr CR Suvarna)



Class VI: Root fracture with or without loss of crown structure Class VII: Displacement of tooth without crown or root fracture Class VIII: Fracture of crown en mass Class IX: Fracture of deciduous teeth.

HOW DO WE MAKE DIAGNOSIS IN CASE OF DENTAL TRAUMATIC INJURIES? Correct diagnosis is based on: • History taking: Details of the traumatic event and the relevant medical history. • Clinical examination: – Extraoral: Evaluate facial hard and soft tissues for laceration, bone fracture, etc. – TMJ and occlusion: Careful examination of temporo­ mandibular joint should be done. Occlusion should be checked. Abnormalities in occlusion can indicate alveolar bone or jaw fracture – Intraoral: - Soft tissues: Evaluate oral soft tissues—Lips, tongue, cheek, floor of mouth, etc. for lacerations and other injuries. - Teeth and supporting tissues: Visual examination, tactile inspection and palpation, percussion and mobility testing. • Diagnostic tests: Pulpal tests – Thermal and electric pulp tests: - May give false negative readings. This is because due to traumatic injury, the conduction capability of the nerve endings or sensory receptors may get

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Fig. 24.4  Discolored nonvital right maxillary central incisor due to trauma without any loss of crown structure and trauma to the left side central incisor involving enamel and dentin (Courtesy of Dr CR Suvarna)

deranged and may inhibit the nerve impulse from an electric or thermal stimulus. - A positive response at the initial examination may get converted to a negative response at a subsequent visit indicating degeneration of pulp or a negative response initially may get converted to a positive response indicating healthy pulp. - To have a baseline data, these tests are performed at the initial examination and then they are repeated at 3 weeks, at 3, 6 and 12 months and at yearly intervals following the accident. - Electric pulp tests do not give predictable results in young teeth but may be useful in elderly patients or in traumatized teeth that are undergoing premature sclerosis. – Laser Doppler flowmetry: Laser Doppler flowmetry (LDF) is a valuable diagnostic test in assessing vitality in traumatized teeth. It helps identify ‘at risk’ teeth early after trauma. LDF detects blood flow more consistently and earlier in traumatized teeth than the standard tests. • Radiographic examination: – Standard radiographs: Panoramic view (OPG), IntraOral Periapical Radiograph (IOPA) – Many angled radiographs have to be taken for correct diagnosis. – The International Association of Dental Traumatology recommends three angulations for radiographs of traumatized teeth, including: i. Occlusal view ii. Lateral view (from mesial or distal aspect of tooth)

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iii. Horizontal angle of 90 degrees with central beam through the tooth. – Radiographs can be useful to detect: - Any embedded foreign objects - Bone fractures - Root fractures - Subgingival crown fractures - Root or bone resorption – But, hairline fractures or fractures that run in a mesio­ distal direction may not be evident on radiographs. • Clinical photographs: Photographs are taken to serve as record for monitoring the patient and progress of the treatment and also for documenting the injuries for legal purposes.

– Lateral luxation – Extrusive and intrusive luxation • Tooth avulsion.

WHAT ARE THE FACTORS TO BE CONSIDERED FOR TREATMENT OF TRAUMATIZED TEETH?

• Uncomplicated fractures of crown and their manage­ ment: – The uncomplicated crown fractures may involve only enamel or enamel and dentin, but there is no pulp exposure. It is not usually associated with pain or any symptoms. – If fracture involves only enamel, then selective grinding of incisal edges in order to remove sharp edges is done. (Enameloplasty). – Fractures involving only enamel can be very well treated using composite restorations. – If fracture involves enamel and dentin, it can also be treated using composite restorations. A protective liner may be needed if the fracture has occurred at deeper level approaching the pulp. – If the fractured fragment is available, it can be reattached by etching and bonding technique.

Figure 24.5 gives the factors to be considered for treatment of traumatized teeth in the form of a mind-map.

WHAT ARE THE DIFFERENT DENTAL TRAUMATIC INJURIES AND THEIR MANAGEMENT? We shall discuss the following dental traumatic injuries and their management: • Crown fractures • Crown-root fractures • Root fractures • Luxation injuries – Concussion – Subluxation

Crown Fractures

Fig. 24.5  A mind-map to remember all points of factors determining treatment of traumatized teeth

Management of Dental Traumatic Injuries

– Carry out follow-up tests after a week, a month, 3  months, 6 months and a year to check the changes in the condition of the pulp - Normal response of pulp at following visits: Indicates that pulp has recovered - Abnormal response of pulp at follow-up visits: Indicates unfavorable prognosis of pulp or pulp necrosis and need for Endodontic treatment. • Management of complicated fractures of crown: When the fracture involves enamel, dentin and pulp, it is called complicated fracture of the crown. – Treatment options for complicated crown fractures include:

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• Bacteria-tight seal: – Bacterial contamination during healing phase can cause failure of VPT. – If exposed pulp is effectively sealed against bacterial leakage, healing of pulp occurs with a hard-tissue barrier. • Pulp dressing: – Calcium hydroxide is commonly used in dressing for vital pulp therapy that disinfects the superficial pulp with its antibacterial effect and causes liquefaction necrosis of superficial layers of inflamed pulp forming a hard tissue barrier. – Only disadvantage of calcium hydroxide is that it does not seal fractured surface, as a result of which additional material must be used to have bacterial seal. – Mineral trioxide aggregate (MTA) has been tried as pulp capping agent with good results.

Pulp Therapies in Traumatized Teeth Various pulp therapies have been discussed in detail in Chapter 27: Pulp Therapies and Chapter 28: Pediatric Endodontics. Here they will be explained in short, in relation to traumatic injury.

Vital Pulp Therapy

– Choice of treatment depends on following factors: (Remember the sentence): Decide To Repair Pulp (Development, Time, Restorative treatment plan, Periodontal injury) (Fig. 24.6).

REQUIREMENTS FOR SUCCESS OF VITAL PULP THERAPY IN CASE OF TRAUMATIZED TEETH • Noninflamed pulp and less time elapsed: – Vital pulp therapy (VPT) of noninflamed pulp has high success rate. – Within first 24 hours of injury, pulp inflammation may be only superficial and if vital pulp therapy is carried out during this time, it can have favorable results. – With increasing time between injury and therapy, pulp removal must be extended apically to ensure that noninflamed pulp has been reached.

• Pulp capping for traumatized teeth: – In few traumatic exposures, a superficial pulp cap in the form of a dressing such as calcium hydroxide can be placed directly onto pulp exposure. This is called direct pulp capping. Figures 24.7A to C shows diagrammatic represen­ tation of direct pulp capping using calcium hydroxide for a traumatized tooth and calcific bridge formed after a few weeks of treatment. – Success rate: 80% – Disadvantages: - Soon after traumatic exposure, superficial inflam­mation of pulp occurs. With pulp capping, inflamed rather than healthy pulp is treated. So, potential for success is lowered. - Due to limited depth of cavity, it is difficult to achieve a bacteria-tight coronal seal. Due to these difficulties, pulp capping is less commonly used treatment modality for traumatized teeth. • Partial pulpotomy/Cvek pulpotomy: – It involves removal of the superficial inflamed pulp tissue.

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Fig. 24.6  A mind-map to remember all points of factors determining choice of treatment of complication fractured crown

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C

Figs 24.7A to C  Direct pulp capping in traumatized tooth: (A) a: Denotes pulp exposure due to trauma (B) a: Direct pulp capping with calcium hydroxide b: Tooth restored with semipermanent restoration (C) Few weeks later a: Calcific bridge formation b: Calcium hydroxide c: Glass ionomer cement base d: Permanent restoration (Composite built-up)

– Technique: Steps include: - Isolation : Rubber dam placement after administration of anesthesia - Cavity preparation : 1–2 mm deep cavity preparation with diamond bur at high speed with copious water coolant. - Hemostasis: Pulp is amputated to the level where only mild to moderate hemorrhage is seen. Sterile  saline or anesthetic solution used to rinse the area. - Placement of calcium hydroxide: The pulpal cavity and exposed dentinal tubules covered with hardsetting calcium hydroxide. - Bacteria-tight seal: Glass ionomer cement is filled in the prepared cavity for a bacteria-tight seal. - Restoration: Etching and bonding for composite resin restoration. – Advantages: - Superficial inflamed pulp tissue is removed. So, more chances of success. - Space is provided for a material such as glass ionomer to provide a bacteria-tight seal to allow pulpal healing. – Success rate: It is 94–96%.

Management of Dental Traumatic Injuries

• Full pulpotomy: – When it is predicted that pulp is inflamed to deeper levels of coronal pulp, the entire coronal pulp to the level of root canal orifices is removed. This is called full pulpotomy. – Indications: - Traumatic exposure after 72 hours - Carious pulp exposures This is the treatment modality in the immature teeth with incompletely formed root apices. But, it is contra­indicated in mature teeth. – Technique: Steps include: - Rubber dam placement after administration of local anesthesia - Removal of coronal pulp to the level of the root canal orifices - Calcium hydroxide is placed over the floor of pulp chamber and glass ionomer placed to achieve a bacteria-tight seal - Coronal restoration

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- After the roots are formed completely, pulpectomy can be done and root canal treatment completed as usual. – Success rate: It is 75% (prognosis poorer than partial pulpotomy due to arbitrary site of pulp amputation. There may be inflamed pulp sometimes extending past the root canal orifices. This may result in treatment of an inflamed rather than noninflamed pulp. Thus reducing the success rate). A mind-map to remember all points of vital pulp therapy for traumatized teeth is given in Figure 24.8.

Nonvital Pulp Therapy Pulpectomy • Mature tooth: Pulpectomy involves removal of the entire pulp to the  level of apical foramen. In case of a mature tooth with root apices closed, this is completed like the routine Endodontic treatment involving access

Fig. 24.8  A mind-map to remember all points of vital pulp therapy for traumatized teeth

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preparation, thorough cleaning and shaping followed by obturation. • Immature tooth: – Apexification: In case of immature teeth with open apices, and thin dentinal walls, apexification procedure needs to be carried out to form a hard-tissue apical barrier against which an effective root canal filling can be done and to reinforce the weakened root against fracture both during and after apexification. Other details of Apexification are given in Chapter 27 “Pulp Therapies”. – Technique: Steps include: - Access cavity preparation: Determination of provisional working length with the help of a preoperative radiograph and confirmed radiographically by placing the first Endodontic instrument. - Since the dentinal walls are thin, preparation of canal is performed very lightly and with copious irrigation using 0.5% sodium hypochlorite. - Canal is dried with paper points and calcium hydroxide intracanal dressing may be placed for about 1 week for disinfection of the canal. After 1  week, the further treatment can be carried out.

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B

• Traditional method: A mix of pure calcium hydroxide powder with sterile saline (or anesthetic solution) or ready mixed commercially available calcium hydroxide is packed against the apical soft tissue using a plugger. Then the remaining canal is back filled with calcium hydroxide to the level of root canal orifices. Access cavity is filled with a well-sealed temporary filling. Radiograph is taken to ensure the entire canal has been filled. Patient is recalled at 3-months intervals and radiograph is taken to evaluate the formation of hard tissue apical barrier. It may take about 3–18 months for the barrier to form. If in between appointments, calcium hydroxide wash out is seen, it is replaced as before. After the hard tissue barrier is evident on radiograph and tactile sensation with an Endodontic instrument, the calcium hydroxide is washed out of the canal with sodium hypochlorite. The canal is then filled against the apical stop but with careful softened filling technique without application of excessive lateral forces during filling. Care must be taken to ensure that the root canal filling is completed to the level of hard tissue barrier and not forced beyond it. • MTA Barrier: After the disinfection of the canal, calcium sulfate is pushed through the apex to form a resorbable extraradicular barrier against which MTA can be packed. MTA is mixed with sterile water and placed into the apical 3–4 mm of the canal. Radiograph is taken to confirm its placement. A wet cotton pellet has to be placed against MTA plug and left for about 6 hours for MTA to set and then the entire canal can

C

D

Figs 24.9A to D  (A) Immature pulpally involved maxillary right central incisor with rubber dam in place; (B) Apical plug of MTA; (C) Obturation completed with thermoplasticized gutta-percha; (D) Follow-up radiograph after 6 months (Courtesy of Dr Roheet Khatavkar)

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Fig. 24.10  A mind-map to remember all points of nonvital pulp therapy for traumatized teeth



be obturated. Alternatively, the obturation can be done at the same appointment considering that the tissue fluids of open apex will provide moisture for MTA to set. Figures 24.9A to D shows the radiographs of maxillary right central incisor tooth in which apexification has been done using MTA. A mind-map to remember nonvital pulp therapy for traumatized teeth is given in Figure 24.10.

Crown Root Fracture • Presents a periodontal challenge • For crown-root fractures, periodontal treatment is done first to allow for a good margin for restoration.

• If the tooth can be maintained periodontally and can allow for a well sealed coronal restoration, then the tooth is treated as crown fracture.

Root Fractures Root fractures involve the cementum, dentin and pulp. • According to the level of fracture, root fractures can be classified as:

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• According to the direction of fracture, root fractures can be classified as:

• Consequences of treatment: At follow-up visits, it may be found that:

Coronal Root Fractures • In case of fracture at the level of or coronal to crest of alveolar bone, prognosis is poor. The coronal segment needs to be extracted if the fractured segments cannot be reattached. Then the remaining root segment can be orthodontically extruded for the restoration to be fabricated. • In case of fractures below the level of crest of alveolar bone, reattachment of segments and adequate splinting will allow for favorable healing.

Mid-root and Apical-root Fractures • Necrosis may occur in the coronal segment with the apical segment remaining vital or there may be necrosis of both the coronal and the apical segments. • If periapical lesion is seen in the apical segment, the coronal root segment should be Endodontically treated and the use of MTA or calcium hydroxide to form a hardtissue apical barrier can be considered in case of a wide apical canal lumen. • In case of mid-root fractures, removal of the apical segment may compromise the remaining attachment and the crown-to-root ratio. So, careful assessment needs to be done. • In case of apical 1/3rd fractures, if necrosis has occurred in the apical segment, this necrotic apical segment can be surgically removed, if the remaining root can provide adequate periodontal support. • Follow-up visits after splinting at 3 months, 6 months and 12 months are carried out to evaluate the prognosis of the tooth.

Luxation Injuries Luxation injuries cause damage to the attachment apparatus (periodontal ligament and cemental layer). • Types of luxation injuries: Given on next page. • What happens after luxation injuries?

• Management of luxation injuries: Concussion and subluxation: – Generally do not have any pulp consequences. Such teeth should be kept under observation and pulp tests performed at each follow-up visit. – Pulp test findings: i. Repetitive finding of positive response can be considered to be a sign of healthy pulp. ii. Transition from positive to negative response can be an indication that pulp is undergoing degeneration.

Management of Dental Traumatic Injuries

iii. Transition from negative to positive response may occur if circulation is restored. iv. Persistence of negative response can be considered to be a sign of irreversibly damaged pulp and Endodontic treatment is indicated. – Immobilize the injured teeth using a splint. – Relieve the occlusion by selective grinding of cusps of opposing teeth. Lateral luxation and extrusive luxation: – If displacement of tooth (Luxation) occurs without fracture: a. Immediate management: Reposition the tooth as soon after the accident as possible and place a functional splint. Anesthesia needs to be administered and then reposition the tooth with minimal force by moving it coronally (out of buccal bone plate) and then apically (into its original position). Splint can be removed in 2 weeks. b. Late: Orthodontic treatment. – Evaluate the width of apical constriction at the time of repositioning. - If width is 1 mm or more: It is considered that revascularization will occur. No treatment, but tooth kept under observation. - If width is less than 1 mm: Root canal treatment should be initiated immediately. Intrusive luxation: Most severe traumatic injury. – Immature tooth: May re-erupt and revasculari­zation may occur. Observe for 4–6 weeks. If re-eruption stops before normal occlusion is attained, then orthodontic treatment is started to prevent ankylosis. – Mature tooth: Pulp necrosis generally occurs. Endodontic treatment is indicated. Severe injury to PDL can lead to complications such as

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replacement resorption and further dentoalveolar ankylosis. Objective of treatment is to prevent such complications. Severely intruded tooth may require surgical access to attach orthodontic appliances for extrusion of tooth. – Primary tooth: If it gets intruded, it usually re-erupts but may deviate the path of the permanent tooth bud. So, immediate treatment may be needed.

Tooth Avulsion Also called total luxation or exarticulation. It is the complete displacement of the tooth out of the socket. Tooth avulsion is treated by replantation, which refers to replacement of tooth in its socket, with the object of attaining reattachment when the tooth has been completely avulsed from its socket. • Management of an avulsed tooth: Management of an avulsed tooth considers the following factors:

Ideally, an avulsed tooth must be replanted as soon as possible and should be functionally splinted. • Management of an avulsed tooth with extraoral dry time of less than 60 minutes and with a closed apex: – Rinse the root with water or saline – Replant the root in the socket gently – On second visit (after 7–10 days) consider Endodontic treatment.

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– Obturation can be done immediately if clinical and radiographic examinations do not indicate pathosis – But if signs of resorption are present, long-term calcium hydroxide therapy can be given until an intact lamina dura can be traced – After obturation of root canals, tooth should receive a permanent restoration as soon as possible to obtain a good coronal seal – Follow-up visits at 3 months, 6 months and 12  months. • Management of an avulsed tooth with extraoral dry time of less than 60 minutes and with an open apex: – It is recommended to soak the avulsed tooth in doxycycline or cover it with minocycline for about 5 minutes and then rinse off the debris gently. – Replant the tooth in the socket gently – In case of an avulsed tooth with open apex, the revascularization of the pulp and continued root development are expected. – But if signs of infection appear, then apexification procedure followed by Endodontic treatment is indicated and performed in the second visit which is after 7–10 days. • Management of an avulsed tooth with extraoral dry time of more than 60 minutes and with a closed apex: – It is recommended that all the remaining periodontal ligament cells be removed from the root in order to make it resistant to resorption and slow down the ankylosis, on replantation. This is done by: – Soak the avulsed tooth in etching acid for 5 minutes – Then soak it in 2% stannous fluoride for 5 minutes – Replant the tooth in the socket gently – Extraoral Endodontic treatment may be performed in the avulsed tooth before replanting it, under absolutely aseptic conditions But, this step has not been found to have any advantage. – After 7–10 days, Endodontic treatment and other considerations similar to teeth with extraoral time less than 60 minutes. • Management of an avulsed tooth with extraoral dry time of more than 60 minutes in a tooth with open apex: Due to potential complications involved with replantation of such teeth, whether to replant such teeth or not is controversial.











If decision is made to replant it, it is recommended that Endodontic treatment be performed extraorally and seal the blunderbuss apex and then replant it. If Endodontic treatment is not possible at the emergency visit and the avulsed immature tooth has been replanted, then the apexification procedure is initiated in the second visit. Adjunctive therapy: It involves: – Administration of antibiotics: - At the time of replantation and before Endodontic treatment - Tetracycline affects the motility of osteoclast and reduces the effectiveness of collagenase - Penicillin V can also be beneficial – Chlorhexidine rinses for 7–10 days to control the bacterial content of the sulcus – Administration of analgesics if required. Physiologic storage media for avulsed tooth if immediate replantation is not possible: If the avulsed tooth cannot be replanted immediately, the tooth should be placed in physiologic storage solution in order to have an extended extraoral time to minimize resorption complications after replantation. Examples of such physiologic storage media in order of preference are: – Hank’s balanced salt solution (HBSS): It is a pH preserving fluid that can keep the periodontal ligament cells viable for 24 hours. – Milk – Saliva – Physiologic saline – Water. Water is least desirable storage medium because the hypotonic environment of water may cause rapid cell lysis and hence there may be increased inflammation on replantation. Outcome of replantation: – If extraoral dry time is less than 15–20 minutes, periodontal healing is expected to occur. The PDL cells maintain their viability and repair after replantation with minimal destructive inflammation. – If extraoral dry time has been more and excessive drying has occurred before replantation, the damaged periodontal ligament cells elicit a severe inflammatory response, large area of root surface gets affected that has to be repaired by new tissue. Replantation

Management of Dental Traumatic Injuries

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TABLE 24.1  Management of dental traumatic injuries (Courtesy of Dr Ashwin Jawdekar) Injury

Management

Enamel fracture

Enameloplasty, fragment reattachment, composite

Enamel and dentin fracture

Fragment reattachment, composite, pulp protection

Pulp exposure

Pulp capping, pulpotomy, apexification, RCT, composite, crown

Nonvital tooth

RCT, composite, crown

Lost (Avulsion)

- Replantation and splinting for 2–3 weeks; OR - Replacement of missing tooth: RPD/FPD; implant

Root fracture

Coronal third—Orthodontic extrusion or crown lengthening, core-build, crown; extraction (poor prognosis) Middle third—Splinting for 3 months, RCT Apical third—Splinting for 1 month, RCT (good prognosis)

Displacement without fracture

Lateral luxation, extrusion: Immediate—repositioning; late—orthodontic movement Intrusion—observe for re-eruption 4–6 weeks, orthodontic treatment If nonvital, RCT

En masse crown fracture

Extraction; orthodontic extrusion or crown lengthening, core-build, crown (poor prognosis)

Traumatic injuries to primary teeth

Avulsion—no replantation as ankylosis may develop Intrusion—usually re-erupt; may deviate path of permanent tooth bud Root fractures—coronal and middle third- extraction Crown en masse fracture—extraction Displacement—immediate-repositioning, late- extraction Splint for less period (2 weeks)



resorption may occur which is frequently followed by ankylosis (osseous replacement or replacement resorption). The pathologic resorption associated with avulsed tooth has been explained in detail in Chapter 30 “Pathologic Tooth Resorption”. Table 24.1 gives the summary of the management of the dental traumatic injuries.

BIBLIOGRAPHY 1. Cohen S, Hargreaves KM. Pathways of Pulp. 9th edn. St. Louis: Mosby, 2006.pp.610-46. 2. Grossman L, Oliet S, Del Rio C. Endodontic Practice, 11th edn. Varghese publication, 1991.pp.278-88, 329-33. 3. Ingle J, Bakland L, Baumgartner J. Ingle’s Endodontics, 6th edn. BC Decker Inc, Hamilton, 2008.pp.1330-53.

CHAPTER

25

Endodontic-Periodontal Inter-relationships

This chapter deals with various aspects of Endodontic-Periodontal inter-relationships, the differential diagnosis of the disease process and the appropriate treatment modality for the same.   You must know • How are Endodontic and Periodontal Tissues and their Diseases Inter-Related? • What are the Etiologic Factors and Contributing Factors causing Endodontic-Periodontal Diseases? • How do we Classify Endodontic-Periodontal Lesions? • How to Detect Endodontic Periodontal Lesions? • What Differential Diagnosis will you Consider when you see Features of Both Endodontic and Periodontal Lesions? • Which are the Different Types of Endodontic-Periodontal Lesions? • What are the Treatment Alternatives in case of Endodontic-Periodontal Lesions? • What is the Prognosis of a Tooth with both Endodontic and Periodontal Disease?

HOW ARE ENDODONTIC AND PERIODONTAL TISSUES AND THEIR DISEASES INTER-RELATED? The tooth, its pulp and its supporting structures together constitute a ‘biologic unit’. The pulp and the periodontium evolved from the same mesenchymal tissue during the formative stage. Except for enamel, which is an ectodermal derivative, all the other dental structures are formed by neural crest cells that later condense in developing maxilla and mandible as dental papilla and dental follicle. The dental papilla gives rise to the dental pulp and the dental follicle gives rise to the periodontal structures. Thus, the pulp and the periodontium are embryologically and structurally related.

Intercommunication between Pulp and Periodontal Tissues There are intimate anatomic and vascular connections between the pulp and periodontium through various pathways as given here.

Pathways of communication between pulp and periodontium: A. Physiologic modes of communication: 1. Apical foramen 2. Lateral canals, accessory canals and furcation canals 3. Exposed dentinal tubules: When cementum and enamel do not meet at CEJ, dentinal tubules remain exposed acting as pathway of communication between the pulp and the periodontium. B. Pathologic modes of communication: 1. Exposed dentinal tubules in areas devoid of cementum due to: a. Developmental defects such as palatogingival groove, cervical enamel projections b. Root caries 2. Idiopathic root resorption 3. Pathologic root perforations 4. Vertical root fractures (VRF) 5. Trauma C. Iatrogenic: 1. Exposed dentinal tubules following periodontal therapy such as root planning

Endodontic-Periodontal Inter-relationships

2. Accidental perforations during Endodontic treatment 3. Surgical procedures.

Inter-relationship between Diseases of the Pulp and the Periodontium • Endodontic lesions can cause periodontal lesions Inflammatory products from diseased pulp, necrotic debris, bacterial by products and toxins Through apical foramen and lateral and accessory canals ↓ Inflammation in periodontium involving PDL only or tooth socket and surrounding bone Toxic irritants of periodontal tissue destruction migrate towards gingival margin: Retrograde periodontitis. • Periodontal lesions can cause Endodontic lesions

One of the main goals of Endodontics is to cure apical periodontitis. Thus, Endodontics may be thought of as periapical Periodontics.

WHAT ARE THE ETIOLOGIC FACTORS AND CONTRIBUTING FACTORS CAUSING ENDODONTIC-PERIODONTAL DISEASES? Etiological Factors • Bacteria: Root canal flora consists of proteolytic bacteria and anaerobic microbiota. Spirochetes are associated with both periodontal (subgingival plaque) and Endodontic diseases (root canals). The spirochetes Treponema denticola and Treponema maltophilum have been isolated from root canals. Porphyromonas gingivalis, Bacteroides forsythus, Prevotella intermedia, etc. are few periodontal pathogenic bacteria. • Fungi: Fungi mainly Candida albicans is found both in Endodontic and periodontal lesions. Fungi may enter the root canals from oral cavity due to poor asepsis

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during root canal treatment procedures. Fungi are found in subgingival plaque. • Viruses: Viruses have also been found associated with both Endodontic and Periodontal diseases. Herpes Simplex virus has been isolated from the gingival crevicular fluid and gingival biopsies of the periodontal lesions. Pulpal and associated periapical disease containing human cytomegalovirus and Epstein Barr virus have been found in few clinical studies. Herpes simplex virus has not been detected in periapical lesions. (The microbiology of root canals has been discussed in detail in Chapter 6 Endodontic Microbiology).

Contributing Factors • Inadequate Endodontic treatment: Poor Endodontic treatment results in treatment failure contributing to Endodontic-periodontal disease. • Traumatic injuries of teeth may involve the pulp and even the surrounding periodontal attachment apparatus. Traumatic injuries and their management has been discussed in detail in Chapter 24. • Coronal leakage: Coronal leakage has been found to be one of the major causes of Endodontic treatment failure. Endodontically treated teeth may get contaminated by microorganisms due to defective restorations or delay in placement of coronal restoration. An adequate coronal restoration is essential to prevent coronal leakage. • Root Perforations: May be pathologic caused due to extensive carious lesion, resorption, etc. or may be iatrogenic (Operator error during post preparation or access preparation or root canal instrumentation.) It can lead to periodontal lesions. Sealing of the perforation as early as possible and infection control is important for good prognosis. Mineral trioxide aggregate (MTA) is widely used perforation repair material. • Developmental malformations: Radicular invaginations found in central fossa of maxillary central and lateral incisors crossing cingulum and continuing till the root can lead to untreatable periodontal condition when its epithelial attachment is breached, resulting in infrabony pocket formation. This condition may get associated with Endodontic disease. (Remember the sentence: Contributing To Endo-Perio Disease: Coronal Traumatic Endodontic Perforations Developmental). Figure 25.1 is the mind-map listing the etiologic and contributing factors for Endodontic-periodontal disease.

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Fig. 25.1  Mind-map of etiologic and contributing factors causing Endodontic periodontal diseases

HOW DO WE CLASSIFY ENDODONTICPERIODONTAL LESIONS?

determines the type of therapy required and probable prognosis of the case.

Due to close relationship between Endodontics and Periodontics, various classifications of Endodonticperiodontal lesions have been suggested in order to divide the type of cases that may require combined (Endodonticperiodontal) or single therapy. • Classification given by Simon et al:

• Classification given by Weine: Weine classified the Endodontic-periodontal lesions based on etiology which

• Classification given by Oliet and Pollock: Oliet and Pollock classified the Endodontic-periodontal lesions based on the required treatment procedure as follows:

Endodontic-Periodontal Inter-relationships

HOW TO DETECT ENDODONTIC PERIODONTAL LESIONS? Pulpal and periodontal diseases have common clinical symptoms such as tenderness to percussion and swelling and may mimic each other clinically and radiographically. Correct diagnosis of the etiology of the disease process, whether Endodontic, periodontal, or combined will determine the treatment and long-term prognosis of the case. Close relationship between pulpal and periodontal disease is reasonably established based on: Case history taking • Chief complaint of the patient • Medical history review Clinical examination and diagnostic tests • Visual examination and palpation to assess the signs and symptoms

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• Presence of swelling: A swelling related to the dental pulp commonly found in the mucobuccal fold. Swelling related to the periodontal problem occurs on the attached gingiva. • Percussion: – Tenderness to percussion in coronoapical direction usually indicates pulpal pathology – Tenderness to percussion in lateral direction usually indicates periodontal pathology. • Pain: Usually sharp/severe/acute onset pain is related to pulpal pathology and chronic, dull discomfort is related to periodontal pathology. • Distribution: Periodontitis is usually generalized and pulpal pathology usually localized, affecting single tooth. • Etiological factors: Periodontal problem is usually associated with local irritating factors such as plaque and calculus and caries or trauma is associated with the pulpal problem. • Pulp tests: Tooth which is pulpally involved may have nonvital pulp and tooth which has only periodontal involvement is vital.

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• Tracing sinus tract or fistula, if present. Mostly related to a pulpal problem. • Pocket probing: Pocket relates to a periodontal problem if the tooth is vital. But in case of pocket associated with a nonvital tooth, there is possibility of an Endodontic problem. Long and narrow pocket related to a single isolated tooth is suggestive of Endodontic problem. Pockets with wide entrance are suggestive of periodontal problem. • Probing of furcation defect, if any. Usually related to periodontal disease. • Tooth mobility-determination. Mobility involving multiple teeth other than the involved tooth, is more related to Periodontal problem.

radiographic and histopathological findings. These should be considered for differential diagnosis. A very simplified table to explain these similarities and differences which is as follows: (Cohen’s ‘The Pathways of Pulp’– 9th Edition’, p. 657).

Radiographic examination • Extent of caries or restorations. • Status of any Endodontic treatment done in the tooth • Condition of periradicular tissues: Thickness of PDL, changes in alveolar bone such as bone loss • Root resorption • Wide periapical radiolucency may be suggestive of pulpal problem. Crestal bone loss, horizontal or vertical bone loss is suggestive of periodontal problem. • Gutta-percha point inserted in the sinus tract and radiograph taken, helps to identify the source of infection.

  –  Inflammation

Acute, sometimes chronic Chronic

  – Periodontal pockets

Single, narrow

Multiple, wide coronally

  –  pH value

Often acidic

Usually alkaline

  –  Trauma

Primary or secondary

Contributing factor

  – Microorganisms

Few

Complex

WHAT DIFFERENTIAL DIAGNOSIS WILL YOU CONSIDER WHEN YOU SEE FEATURES OF BOTH ENDODONTIC AND PERIODONTAL LESIONS? Clinical signs and symptoms and radiographic evaluation help the clinician to rule out different diseases: It may be: • Primary Endodontic or Periodontal lesion with secondary involvement resulting in a combined lesion. • Vertical root fractures: Difficult to diagnose as it may not be detectable by clinical inspection and radiographic examination unless the root fragments have separated. Exploratory surgical exposure of the root for direct visual examination can give definitive diagnosis. • Developmental grooves: Such as palatogingival grooves found in maxillary central and lateral incisors should be looked for as it might have caused the defect. Localized Periodontal destruction occurs due to such grooves. Pulp of such teeth may become secondarily involved. There are certain similarities and differences in the pulpal and Periodontal diseases in terms of clinical,

Endodontic disease

Periodontal disease

Infection of pulp

Infection in periodontium

•  Clinical findings:   –  Etiology

  –  Vitality of tooth Nonvital

Mostly vital

  –  Any restoration Deep or extensive

Not related

  – Local irritating Not related factors: Plaque, calculus

Primary cause

•  Radiographic findings:   –  Pattern

Localized

Generalized

  –  Bone loss

Wider apically

Wider coronally

  –  Periapical

Radiolucency

Not often related

  – Vertical bone loss

Absent

Present

•  Histopathological findings:   – Junctional epithelium

No apical migration

Apical migration

  – Granulation tissue

Apical (minimal)

Coronal (larger)

  –  Gingiva

Normal

Some recession

•  Treatment

Root canal treatment

Periodontal treatment

WHICH ARE THE DIFFERENT TYPES OF ENDODONTIC-PERIODONTAL LESIONS? Primary Endodontic Lesions • Deep caries, extensive restorations or traumatic injury associated with pulpal involvement may lead to Endodontic pathology. The inflammatory components may pass through the apical foramen or lateral/ accessory canals and produce mild inflammation at the apex or near the opening of the lateral/accessory canals.

Endodontic-Periodontal Inter-relationships

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• A deep solitary pocket in the absence of true Periodontal disease is indicative of lesion of Endodontic origin as shown in Figure 25.2. • This pocket is a sinus tract from pulpal origin that opens along  PDL area through lateral accessory canals and apical foramen. • There is no increase in probing depth around the tooth except in the area of sinus tract. • Also, a sulcular pocket of Endodontic origin is typically very narrow compared to pocket of Periodontal origin. • Figure 25.2 shows diagrammatic representation of mandibular molar showing deep carious lesion with infected/necrotic pulp. This lesion has primarily an Endodontic etiology. It shows the various pathways for the spread of infection that include: – from apex to gingival sulcus – from apex to furcation area – from lateral canals to gingival sulcus – from lateral canals to furcation area • Diagnosis: The origin of the lesion can be traced by inserting gutta-percha cone into the sinus tract and taking radiographs. Also, based on findings such as minimal amount of plaque or calculus present, necrotic pulp of the involved tooth.

• Treatment: Root canal treatment. Primary Endodontic lesions usually heal following root canal treatment. The sinus tract extending into the gingival sulcus or furcation area quickly heals by itself following root canal treatment. • Prognosis: Excellent prognosis. The periapical lesion usually resolves if proper Endodontic therapy is done.

Fig. 25.2  Mandibular molar with deep carious lesion. Various pathways for the spread of infection denoted by arrows. a. from apex to gingival sulcus; b. from apex to furcation area; c. from lateral canals to gingival sulcus; d. from lateral canals to furcation area

Fig. 25.3  a. Spread of infection from an Endodontically involved tooth through the apical foramen; b. Deep solitary periodontal pocket formation

Primary Endodontic Lesions with Secondary Periodontal Involvement • When lesion of Endodontic origin is not treated ↓ Pathosis continues to progress causing break-down of surrounding hard and soft tissues. Figure 25.3 shows diagrammatic representation of an Endodontically involved mandibular molar tooth. There is spread of infection through apical foramen and deep solitary pocket is formed. • Root perforation during root canal treatment also causes secondary Periodontal involvement. • Root fractures also mimic the appearance of primary Endodontic lesions with secondary Periodontal involvement. Frequently occurs on Endodontically treated teeth with large post.

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• Diagnosis – Necrotic root canal and plaque or calculus accumulation demonstrated by probing and radiographs. – May be associated with pain, swelling, purulent exudates, pocket formation and tooth mobility. – In cases of root fractures, local deepening of Periodontal pocket and more acute Periodontal abscess symptoms can be found. – Deep solitary periodontal pocket present. • Treatment – Requires both Endodontic and Periodontal treatment. – With Endodontic treatment alone, only part of the lesion will heal. – First Endodontic therapy followed by Periodontal therapy is done. – In case of vertical root fracture, extraction of the tooth. • Prognosis – Good prognosis. – Only in case of vertical root fracture, prognosis of tooth is poor and needs extraction. Primary Periodontal Lesions • Periodontal disease begins in gingival sulcus, migrates to apex as the deposits of plaque and calculus cause breakdown of surrounding alveolar bone and soft tissues. • Accumulation of plaque and calculus and presence of wider pockets.

Fig. 25.4  Radiograph showing Periodontal lesion in maxillary molar

• Mobility of teeth may be seen but in most cases, teeth respond positively to pulp testing. • Treatment: Oral prophylaxis including scaling and polishing of teeth and root planning. Periodontal flap surgery may be needed in some cases. Root amputation may be required in advanced cases. • Prognosis for such teeth depends upon the stage of Periodontal disease. Figure 25.4 shows radiograph of maxillary molar with Periodontal lesion. Primary Periodontal Lesions with Secondary Endodontic Involvement

Figure 25.5 shows diagrammatic representation of mandibular molar with primarily Periodontal involvement. Infection can spread from Periodontal pocket through apical foramen to the pulp as denoted by arrows.

Fig. 25.5  The tooth has no carious lesion and reveals a vital pulp. There is primarily Periodontal involvement. a. Periodontal pocket; b.  Infection can spread to the pulp through the apical foramen

Endodontic-Periodontal Inter-relationships

This can happen when treatment procedures like scaling, curettage or surgical flap procedures open the dentinal tubules and lateral canals to the oral environment. This results in pulp inflammation and necrosis. • Signs and symptoms of pulpal disease as well as Periodontal disease become evident. • Treatment of lesions that are primary Periodontal and secondary Endodontic involvement: – Endodontic treatment – Periodontal procedures such as Scaling and root planning – Periodontal flap surgery may be required in few cases. – In certain conditions like localized Periodontal defect associated with Endodontically untreatable tooth or iatrogenic errors causing Endoperio lesions, certain treatment alternatives need to be considered such as Root resection/amputation or guided tissue generation (GTR), discussed later in this chapter. True Combined Lesions • Pulpal and Periodontal disease may occur independently or concomitantly in and around the same tooth. • True combined lesions occur when Endodontic disease progressing coronally joins with an infected Periodontal pocket progressing apically as shown and explained in Figure 25.6. The Endodontic and Periodontal lesions which were once separate, now communicate. • Diagnosis: Necrotic pulp or failing Endodontic treatment, plaque, calculus and periodontitis may be present in teeth with combined lesions. Figures 25.7A and B show radiographs of mandibular molars with combined Endodontic-Periodontal lesion.

A

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• Treatment : Both Endodontic and Periodontal treatment. After a definitive diagnosis is established, Root canal treatment and/or required Periodontal therapy is considered in the treatment plan. Generally Endodontic treatment should precede Periodontal therapy. • Prognosis depends on the amount of Periodontal destruction. Prognosis is guarded in single-rooted teeth.

Fig. 25.6  a. Caries involving the pulp; b. Spread of infection from Periodontium into the pulp through the lateral canal; c. Periodontal pocket; d. Spread of infection from the infected pulp to the periodontium through the apical foramen resulting in combined lesion

B Figs 25.7A and B  Radiographs of mandibular first molar with both—severe Periodontal lesion and Endodontic involvement

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Concomitant Pulpal and Periodontal Lesion • Lesions that may commonly be seen clinically and reflect presence of two separate and distinct entities are named, concomitant Pulpal and Periodontal lesion. • Both may have different causative factors. • There is no clinical evidence that either disease state has influenced the other. • Both separate lesions have coincidently attacked the same tooth. • Both the disease processes must be treated concomitantly with the removal of individual etiologic factors. • It should be determined whether periodontal condition is treatable. There is no point performing Endodontic therapy in teeth with hopeless periodontal lesions. • Endodontic therapy is performed first followed by Periodontal therapy. • The healing of periapical lesion is not affected by the periodontal therapy to follow. Weine’s classification of Endodontic-Periodontal problems: Weine has suggested a classification of EndodonticPeriodontal problems, that is clinically oriented and helps in determining accurately the correct method of therapy required. The types of Endodontic Periodontal problems according to Weine’s classification are summarized in Table 25.1.

WHAT ARE THE TREATMENT ALTERNATIVES IN CASE OF ENDODONTIC-PERIODONTAL LESIONS? Primary treatment of different Endodontic-periodontal lesions has been explained previously with the different types of Endodontic-periodontal lesions. Treatment alternatives in case of Endodontic-periodontal lesions include the following:

Respective Techniques Root Resection “Radisectomy or root resection is the removal of root with accompanying odontoplasty”. This can be done before but preferably after Endodontic treatment. “Hemisection refers to sectioning of the crown of a molar tooth with either the removal of half of the crown and its supporting root structure or retention of both halves to function as two premolars”. • Indications of root resection: – Root fracture – Root perforations – Root destroyed by extensive caries – Extensive loss of bone around one root due to dehiscence, fenestration, external root resorption – Impaired Endodontic treatment of a particular root – Severe periodontitis involving only one root – Untreatable furcation involvement. • Contraindication: When loss of bone involves more than one root and the remaining root would have inadequate support. In such cases, extraction of such a tooth is recommended. Occlusal function can be restored by considering implants with hybrid prostheses. • Case selection: Root resection is a technique-sensitive procedure that requires careful diagnostic process for selection of case that would be best treated with resection technique. • Accompanying odontoplasty: – Crown: Proper reshaping of occlusal table and resto­ ration of the clinical crown is to be done. – Root: Root surface must be recontoured to remove the root stump. • Prognosis: Long-term prognosis for vital root resection has been found to be poor. Whenever possible, root canal treatment should be done before root resection. If not possible, then it should be performed as soon as possible after vital root amputation.

Regenerative Technique Guided tissue regeneration (GTR) barrier membranes can be used in case of large periradicular lesions to promote bone healing after Endodontic surgery. Bone replacement grafts using guided tissue and bone regeneration techniques reestablish the biologic structures that were lost during the disease process.

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TABLE 25.1  Types of Endodontic-periodontal problems according to Weine’s classification Class I 1. Predominant • Endodontic (Pulp lesion inflammation and/or necrosis) • Simulates periodontal disease clinically and radiographically

Class II

Class III

Class IV

• Both Endodontic and • Severe Periodontal disease •  Periodontal disease Periodontal disease • Has no pulpal problem. • Simulates clinically and concomitantly Needs Endodontic therapy radiographically pulpal or periapical • Pulpal disease may be and root amputation to gain disease and appears to indicate coincidental to Periodontal periodontal healing and need for Endodontic treatment but actually requires Periodontal lesion or may be due to degree retain the tooth therapy only of Periodontal damage

2. Etiology

Endodontic (pulpal disease) Both Endodontic (pulpal and Tooth may have deep periapical) and Periodontal caries, large restoration disease approaching the pulp, pulp capping, pulpotomy, considerable dimunition of pulp space

Periodontal disease. Pulp may Periodontal disease be normal or may have some degree of pulpal inflammation

3. Diagnosis

It is based on finding that patient has minimal or no periodontal disease in other areas of mouth

It is based on finding that periodontal problems are present elsewhere in mouth and that a pulpal pathosis is also present

Periodontal disease present, no pulp damage in the involved tooth. Possibility of retaining the tooth and good periodontal result by means of Endodontic treatment plus root amputation

4. Treatment

Endodontic therapy only

Both Endodontic and Periodontal Here treatment is aimed at Requires periodontal therapy therapy gaining healing of periodontalonly problem. Endodontic therapy and guided tissue regeneration (GTR) or root amputation (indicated in case of severe periodontal defect around one root of multirooted tooth, other roots have healthy support)

5. Prognosis

Heals rapidly. Excellent prognosis. Clinical symptoms disappear after initial root canal debridement. Deep pocket of 8–10 mm reduces to about 2 mm after first appointment of Endodontic treatment. Bone damage gets repaired and remineralized seen on radiograph within one year

Prognosis for periapical portion is superior to that of Periodontal portion. If periapical lesion healed after Endodontic treatment, less chance of recurrence. Periodontal lesion may recur if periodontal maintenance not followed

Other Treatment Alternative: Forced Eruption/Orthodontic Extrusion In cases where surgical crown lengthening cannot be performed or will not give the desired result, orthodontic extrusion can be a better alternative. It is very infrequently used technique. It serves to preserve the natural root system and related periodontal architecture.

Due to loss of bone and soft tissue support due to periodontal disease, affected teeth may become sensitive to changes in temperature which might be misdiagnosed as irreversible pulpitis. Tenderness to percussion and mobility and swelling. Exudate may be expressed from crevice on probing in case of periodontal abscess

Here use of Endodontic Prognosis is poor unless periodontal procedure produces healing treatment is done of periodontal disease and no further periodontal therapy may be required in the area of amputation of involved root

• Indications: – Fractured teeth – Teeth with extensive caries – Teeth with internal or external root resorption – Teeth with lateral perforation – Teeth in which surgical crown lengthening will produce poor prosthesis. • Prognosis is usually poor in case of single-rooted teeth.

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Disease process

Prognosis

•

Primary Endodontic disease Necrotic tooth with or without sinus tract

Excellent prognosis if appropriate Root Canal Treatment is done.

•

Primary Periodontal disease

Excellent, good to poor prognosis depending on severity of Periodontal disease, patient’s tissue response and oral maintenance.

•

Primary Endodontic disease with secondary Periodontal involvement

Good to poor prognosis. Endodontic treatment to be done first, treatment results to be evaluated in 2–3 months and only then Periodontal therapy considered.

•

Primary Periodontal disease with secondary Endodontic involvement or true combined lesions

Guarded prognosis. It depends mainly on severity of Periodontal disease and success of Periodontal therapy.

Prognosis may be better in molar teeth if all the roots have not suffered loss of supporting tissues. Root resection can be considered as treatment alternative.

WHAT IS THE PROGNOSIS OF A TOOTH WITH BOTH ENDODONTIC AND PERIODONTAL DISEASE? Long-term prognosis will be determined by correct diagnosis of the etiology of disease process whether Endodontic, Periodontal or combined. The prognosis of

the tooth as per the type of Endodontic-Periodontal lesion is given in the above table.

BIBLIOGRAPHY 1. Cohen S, Hargreaves KM. Pathways of Pulp, 9th edn. St. Louis: Mosby; 2006.pp.650-65. 2. Franklin S Weine. Endodontic therapy, 6th edn. Mosby-Affliate of Elsevier, St Louis, Missouri; 2004.pp.452-80. 3. Grossman L, Oliet S, Del Rio C. Endodontic Practice, 11th edn. Varghese publication; 1991.pp.313-27. 4. Ingle J, Bakland L, Baumgartner J. Ingle’s Endodontics 6, 6th edn. BC Decker Inc, Hamilton; 2008.pp.638-56.

CHAPTER

26

Surgical Endodontics

This chapter discusses in detail the various aspects of periradicular surgery including the basic principles and step-by-step procedure for performing the surgery.  • • • • • •

You must know What is Endodontic or Periradicular Surgery and what are its Objectives? What are the Indications of Periradicular Surgery? What are the Contraindications of Periradicular Surgery? What is the Contemporary Classification of Endodontic Surgery? What are the Important Considerations While Case Selection and Treatment Planning for Periradicular Surgery? What are the basic Principles and Steps to be followed in Periradicular Surgery?

WHAT IS ENDODONTIC OR PERIRADICULAR SURGERY AND WHAT ARE ITS OBJECTIVES?

WHAT ARE THE INDICATIONS OF PERIRADICULAR SURGERY?

A surgical procedure that allows visualization and manipulation in the periradicular area in order to eliminate pathosis and to place a biocompatible seal by means of retrograde filling through the surgical site is called Endodontic or periradicular surgery.

Grossman gave the following list of indications for periradicular surgery: • When direct access to the apical third of the canal is prevented either due to anatomic conditions such as calcifications, curvatures, bifurcations, etc. or due to iatrogenic errors such as ledging, or blockage from separated instrument, old fillings, posts, etc. • In case of pathologic or iatrogenic apical perforation that cannot be sealed properly by orthograde filling of the canal • In case of lesions that require diagnostic biopsy • In case of “blunderbuss” canals that do not respond to apexification and cannot be adequately sealed with an orthograde filling.

Objectives of Periradicular Surgery • • • • •

To gain adequate access to periradicular area To remove pathological tissue To visualize and evaluate the root and root canal system To place root-end filling in order to achieve a biocompatible apical seal of the root canal To promote regeneration of periodontium.

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• When the apical constricture of the root canal has been destroyed by uncontrolled instrumentation resulting in apical foramen that cannot be adequately sealed with orthograde filling. • For the removal of the foreign body such as extruded filling, cement, instrument from the periradicular area that has resulted in the origin or extension of periradicular disease, • In case of exacerbation of disease during nonsurgical treatment or in case of persistent and unexplainable pain following completion of nonsurgical treatment. • When there is excessively large and intruding periapical lesion that may require marsupialization and decompression procedures for treatment. • In case of a horizontally fractured root tip associated with a periradicular disease. • Failure to heal in spite of good nonsurgical Endodontic treatment. (Friends, we can remember the above indications by using a simple alphabetic formula: a2b2cde2f2 Where a = access, a = apical, b = biopsy, b = blunderbuss, c = constricture, d = disease, e = exacerbation, e = excessive, f = fracture, f = failure) But, with the recent advances in the field of Endodontics in terms of improved visualization with microscope, increased knowledge and improved materials has made primary nonsurgical treatment and nonsurgical retreatment more predictable with increased rate of success. As a result, today there are specific indications for periradicular surgery. Ingle has given the following specific indications for periradiclar surgery: – When nonsurgical retreatment has failed, that implies that nonsurgical treatment had been employed atleast twice. – When the initial or primary nonsurgical treatment provided has failed and retreatment is not possible or practical to achieve a better result. – When a biopsy is necessary.

WHAT ARE THE CONTRAINDICATIONS OF PERIRADICULAR SURGERY?

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WHAT IS THE CONTEMPORARY CLASSIFICATION OF ENDODONTIC SURGERY?

Preoperative Evaluation of Patient

• The contemporary classification of Endodontic surgery: (Ingle’s Endodontics, p.1234)

Thorough evaluation of patient’s medical history and specific assessment of patient’s cardiovascular status and any kind of tolerance to local anesthetics containing adrenaline, is essential. Enquiry about drug history including any known allergy to any medications and about the use of any nonprescription medications that can have interaction with local anesthetics or can inhibit coagulation, is also essential.

Anatomic Considerations Important anatomic structures that may be encountered during Endodontic surgery and the anatomy of the individual root and root canal system should be considered. • Richard Rubenstein and Kim gave the following classification of Endodontic microsurgical cases:

Considerations in Anterior Maxilla • Floor of nose and bony anterior nasal spine in case of extremely long roots of maxillary incisors or a large periradicular lesion that may erode considerable amount of bone. • Amount of lingual inclination of the root of maxillary lateral incisor. • Maxillary canine has long root and if it is combined with a shallow vestibule in a particular patient, then it can complicate access to the apical area.

Considerations in Posterior Maxilla

WHAT ARE THE IMPORTANT CONSIDERATIONS WHILE CASE SELECTION AND TREATMENT PLANNING FOR PERIRADICULAR SURGERY? Important considerations while case selection and treatment planning for periradicular surgery include:

• Maxillary sinus: – Proximity of root apices to the maxillary sinus should be considered: - Apex of buccal root of maxillary 1st premolar is quite away from the floor of maxillary sinus approximately 7.05 mm. - Apices of maxillary 2nd premolar, and that of mesiobuccal and distobuccal roots of maxillary 1st molar are found to be approximately 2.8 mm from the floor of maxillary sinus. - Mesiobuccal root of maxillary second molar is found to be closest to the floor of maxillary sinus, approximately 0.83 mm.   Periradicular pathosis may cause pathologic resorption of bone around the apices decreasing this distance further.

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– Clinician must be prepared for the management and precautions to be taken when the maxillary sinus gets exposed during Endodontic surgery in case of a large periradicular lesion. Sinus opening should be temporarily occluded with appropriate material and prevent the inadvertent displacement of infected root fragments and debris into the sinus. • Palatal roots: Surgical access to the palatal roots of maxillary molars may be difficult. They can be accessed by palatal or buccal (transantral) approach. • Greater palatine foramen: Generally located about 1 cm from the margin of palatal gingiva in between the maxillary second and third molars. This anatomic structure is usually not encountered as very few apical surgical procedures are performed on the palatal roots of maxillary 2nd or 3rd molars. • Anterior palatine artery: Emerges from greater palatine foramen distal to maxillary 2nd molar. Its position should be carefully considered to avoid severing it during incision. But in case if it gets severed, it should be locally clamped and pressure applied for hemostasis.

Considerations in Anterior Mandible • Roots of mandibular incisors are lingually inclined. • Vestibule is shallow in the region of mandibular incisors. • Roots of adjacent teeth are quite close to each other.

Considerations in Posterior Mandible • Position of mental foramen: It may be located between the apex of mandibular first premolar and the mesial root of the mandibular first molar. • Relationship of the root apices to the mandibular canal. • Neurovascular bundle within the mandibular canal that exits through the mental foramen. • Depth of vestibule in mandibular posterior teeth. • Distal root of mandibular second molar is located quite away from buccal cortical plate, meaning that mandibular second molar has quite thick overlying buccal bone and more buccal location of mandibular canal, all these factors cause difficulty in access to the roots of mandibular second molar. A mind-map to remember all points of anatomic considerations for periradicular surgery is given in Figure 26.1.

Fig. 26.1  A mind-map to remember all points of anatomic considerations for periradicular surgery

Surgical Endodontics

WHAT ARE THE BASIC PRINCIPLES AND STEPS TO BE FOLLOWED IN PERIRADICULAR SURGERY? • Preoperative: Patient preparation for surgery – Informed consent – Premedication – Endodontic surgical armamentarium • Endodontic surgical phase: Step 1: Local anesthesia Step 2: Soft tissue surgical access: – Incision – Flap design – Flap retraction Step 3: Hard tissue surgical access—Removal of cortical bone for periapical access Step 4: Periradicular curettage and biopsy Step 5: Management of hemorrhage from the surgical site Step 6: Management of root end: – Root end resection – Root end conditioning – Root end cavity preparation Step 7: Retrograde filling of root Step 8: Closure of surgical site • Postoperative care: – Possible postoperative sequelae – Postsurgical instructions.

Preoperative Phase: Patient Preparation for Surgery Informed Consent • Patient should be informed about the benefits and also the risks involved in the proposed surgical procedure. • Patient should also be explained about the various treatment alternatives other than Endodontic surgery. • Patient should read, understand and sign a written consent form that includes the possibility of different serious complications during surgery. For example, paresthesia following mandibular posterior surgery, damage to neurovascular bundle or Exposure of maxillary sinus, etc. • Patient should be explained that most of the commonly occurring complications related to surgery are selflimiting and are readily manageable such as swelling, bruising, bleeding and sometimes infections.

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Premedication • Preoperative administration of an NSAID, such as Ibuprofen 400 mg is recommended to reduce postoperative pain. • It is recommended that a long-acting local anesthetic be used for pain control for a longer period. • Administration of prophylactic antibiotics depends on general health of patient. It is necessary in case of immunocompromised patients, diabetic patients, patients with cardiac problems, etc. • Chlorhexidine gluconate oral rinses (0.12%) are recom­ mended. – To be started one day prior to surgery – To be used immediately before surgery – To be continued for 4–5 days following surgery. Chlorhexidine causes reduction in number of surface microorganisms in the surgical field and following surgery it creates a favorable environment for wound healing. • It is recommended that sedative-hypnotic drugs such as one of the benzodiazepines be given a single dose at bed time the evening before the surgery and second dose just before the start of the procedure to make the patient relaxed during surgery.

Endodontic Surgical Armamentarium • Increased visibility of surgical site with the help of mag­ nifi­cation and illumination using dental operating microscope, endoscope or orascope. • Newly introduced microsurgical instruments such as ultrasonic tips used for root end preparation (Microsonics) and micromirrors used for root-end inspection, are very useful for increased visibility of surgical site. • Basic Endodontic surgical instrument tray containing – Bard parker handle with a no. 15 blade or a microsurgical scalpel (Also no. 11 and no. 12 blade) – Periosteal elevator – Micro-tissue forceps – Microexplorer, Endoexplorer – Straight handpiece and different burs – Sterile saline – Sterile cotton, cotton pliers – Surgical forceps – Curette

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– Root-end filling material – Micro-mirrors – Microcondensers or micro burnishers and pluggers of different sizes – Needle holder, suturing needle and suture material.

Endodontic Surgical Phase Step 1: Administration of Local Anesthesia • Long-acting local anesthetic is recommended to be administered to reduce postoperative pain. • Objectives of local anesthesia administration are: – Localized hemostasis during and after surgery for a clear, surgical field and reduced patient morbidity following surgery. – Profound and prolonged anesthesia for control of pain and anxiety. • Site and technique of injection: – For maxillary teeth: - Infiltration anesthesia in buccal alveolar mucosa at surgical site and then extended 2–3 teeth on either side and a palatal injection. This helps achieve both anesthesia and hemostasis. - A supplemental block injection may be required for maxillary posterior teeth. - Palatal approach to anterior middle superior nerve may be required for maxillary anterior teeth. – For mandibular teeth: - Inferior alveolar nerve block will provide anesthesia - Additional injection in the soft tissue in the immediate area of surgery for hemostasis.   Always ensure that profound adequate anesthesia has been achieved prior to starting the procedure.

Step 2: Soft Tissue Surgical Access Good surgical access is required for proper visibility of the surgical site and for performing the required surgical procedure meticulously and depends on: • Correct location and adequate extent of incisions • Appropriate flap design • Proper reflection of flap. Incisions Give clean, atraumatic incision using scalpel blade no. 11 and 15 starting with a horizontal incision (with no. 11) followed by vertical releasing incision (with no. 15).

• Vertical incision: Vertical releasing incision is desirable since it: – Severs fewer vessels, thus less hemorrhage – Since blood supply to the tissue coronal to incision is preserved, there is prevention of localized ischemia and tissue sloughing – Enhanced healing: Severely angled vertical incision should be avoided. Certain principles should be kept in mind while placing vertical incisions: - Make ver tical incision parallel to the supraperiosteal vessels in the attached gingiva and submucosa. - Place incisions over solid healthy bone. - Place incisions superior to bony eminence and not over the radicular eminence. - Incision should not be made across major muscle attachment and frenal attachment. - Do not dissect the dental papilla, either include or exclude it.   Vertical incisions are placed vertically between adjacent teeth over interdental bone. • Horizontal incision: – The vertical incision intersects the horizontal incision and ends in the intrasulcular area at mesial or distal angle of tooth. – Horizontal incision should be adequately extended to include atleast one or two teeth lateral to the tooth being treated. – Horizontal incision may be the form of an intrasulcular incision that includes the interdental papilla so that the entire papilla is completely mobilized. – It can be an intrasulcular incision that excludes the interdental papilla. In this, the incision starts at the base of papilla and is then directed to the crestal bone. It is called papillary based incision. – Horizontal incision can be made in the attached gingiva retaining about 2 mm of attached gingiva. – Papillary-based horizontal incision is desirable in esthetic anterior regions since it prevents papillary recession and surgical cleft or double papilla. Flap Design Principles of flap design • Base of the flap should always be wider than the free end of the flap so that adequate circulation is maintained in the flap. • Always use firm, continuous strokes while making incisions. Short, intermittent strokes result in ragged margins.

Surgical Endodontics

• There should be continuous curvatures between the hori­zontal and vertical incisions. Sharp angles may tear. • When sinus tract is present, it should be included in the flap. • Releasing incisions should not be over bony eminences but between them, as their overlying tissue is thin and it may get stretched and tear when sutured. • Whenever possible, the sutured flap margins must rest on solid cortical bone plate. Periradicular surgical flaps can be of 2 types: 1. Full mucoperiosteal flap: Involves an intrasulcular horizontal incision in which the marginal and interdental (papillary) gingival tissues are reflected as the part of the flap. It is also called as papillary based flap. – It can be triangular flap formed by horizontal intrasulcular incision and one vertical releasing incision as shown in Figure 26.2. Single vertical releasing incision causes limited surgical access. – It can be rectangular flap formed by horizontal, intrasulcular incision and two vertical releasing incisions as shown in Figure 26.3. This provides good surgical access and may be indicated in case of mandibular anterior teeth or when multiple teeth are involved. There is difficulty in  reapproximation of flap margins with this design. – It can be trapezoidal flap, which is similar to rectangular flap but an obtuse angle is formed where the vertical incision intersects the horizontal and intrasulcular incision as shown in Figure 26.4. There is possibility of severing vital structures and increased bleeding with this flap design. So, it is contraindicated in periradicular surgery. – It can be horizontal or envelope flap created by horizontal and intrasulcular incisions but there is no vertical releasing incision as shown in Figure 26.5. It provides limited access. It may be used in case of cervical defects, hemisections, etc. 2. Limited mucoperiosteal flaps: These flaps have a submarginal, i.e. subsulcular horizontal incision. It does not include marginal or interdental tissues. – It can be semilunar flap formed by giving a curved incision in the attached gingiva and the alveolar mucosa as shown in Figure 26.6. Its horizontal component rests on alveolar bone structure about 3 mm apical to gingival crest and ends in attached gingiva.

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  Generally used in cases when no underlying periodontal problems are present.   It is also called submarginal curved flap.   It is not recommended for periradicular surgery due to its disadvantages such as poor surgical access, poor wound healing, etc. – It can be submarginal scalloped rectangular flap: Luebke-Ochsenbein flap is formed by two vertical incisions connected by a scalloped submarginal horizontal incision in the attached gingiva as shown in Figure 26.7.   This flap gives the advantage of both-vertical flap and semilunar flap. Can be used in case of maxillary teeth where there is adequate amount of attached gingiva. Flap Reflection and Flap Retraction In this step, soft tissues such as gingiva, mucosa and periosteum are separated from the surface of the alveolar bone using a periosteal elevator.

Fig. 26.2  Triangular flap design

Fig. 26.3  Rectangular flap design

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Fig. 26.7  Submarginal scalloped rectangular flap design Fig. 26.4  Trapezoidal flap design

Fig. 26.5  Horizontal or envelope flap design

• Damage to marginal gingiva and the delicate supracrestal root attached fibers should be prevented during tissue reflection as it can cause loss of their viability which results in alteration in the soft tissue attachment levels. • Soft tissues should be handled gently, but firmly to avoid any tearing, puncturing or crushing of tissues during flap reflection and retraction. • Reflected tissue should be kept hydrated by irrigation with sterile saline. Flap reflection: Begins in the vertical incision, few millimeters apical to the junction of horizontal and vertical incisions in a horizontal direction to elevate the periosteum and its superficial tissues from the cortical plate. Then the elevator is directed coronally to separate the marginal and interdental gingiva from the underlying bone undermining the attached gingiva. It has been found that elevation of flap approximately 0.7–0.8 cm apical to estimated apex would allow adequate access to perform the surgical procedure.

Fig. 26.6  Semilunar flap design

Certain principles to be followed during this step include: • While reflection and elevation of flap, microvasculature should be maintained in the body of the tissue flap. This controls hemorrhage during surgery. • Appropriate instrument stabilized with adequate finger support. Stabilization during reflection of flap is necessary to prevent inadvertent slipping of instrument that may cause damage. • It is important that the retractors rest on solid cortical bone.

Flap retraction: After the tissue is reflected, elevation of soft tissues is done in an apical direction to provide adequate surgical access for bone removal and subsequent root end procedures. Flap retraction involves holding the reflected soft tissues in position using appropriate size tissue retractors for good access to radicular and periradicular structures.

Step 3: Hard Tissue Surgical Access This step involves surgical access made through the cortical bone to allow visualization of the root ends. In case of an extensive periradicular lesion, buccal or labial cortical plate may be lost and fenestration may be present with no bone overlying the root whereas in some cases with minimal or no periradicular lesion large amount

Surgical Endodontics

of cortical and cancellous bone may have to be removed to gain access to the root end which can be difficult as exact location of bony window needs to be determined to prevent unnecessary removal of bone. Use of a radiopaque marker can serve as a guidance to determine the position of root apex. • Principles that should be followed during hard tissue surgical access include: – Preservation of healthy bone as much as possible. – Controlling the heat generated during the process. • Hard tissue surgical access is achieved using a round bur in a high speed handpiece with adequate water coolant. – It is important that high speed handpiece that is used should exhaust air from the base rather than the cutting end in order to avoid the risk of air embolism. – Round bur is used to remove bone as it readily allows access of coolant to the cutting surface so that there is minimal inflammation and favorable wound healing. Bone covering the root should be slowly and carefully removed using the round bur in gentle brush stroke action working in an apical direction until the root end is identified. – Use of adequate coolant is essential to control the heat generated during bone cutting and to clear off the debris accumulated on the cutting flutes of instruments. • Technique involves creating a window by preparing 3 openings in the bone, two of the openings through the cortical plate adjacent to mesial and distal sides of root near its apical third and third opening slightly beyond the apex. After completing initial access, extension of window can be done using hand instruments such as chisels as they are less likely to gouge the root. • Next step is to distinguish the root apex from the surrounding bone by following ways: – Radiograph can be taken to serve as the “road map” – Color: Root structure appears more yellowish as compared to bone. – On probing, there is no bleeding from root. – Texture: Bone has granular and porous texture. Root has smooth and hard texture. – Staining dye can be used to identify the periodontal ligament surrounding the root.

Step 4: Periradicular Curettage and Biopsy It is recommended that prior to periradicular curettage, local anesthetic containing a vasoconstrictor be injected

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into the soft tissue mass to prevent any possible discomfort during the process of debridement and for the purpose of hemostasis. • Periradicular curettage is done to: – To remove pathologic tissue associated with root apex such as cyst, granuloma, etc. – To remove any foreign material that had got extruded in the periapical area. – To provide visibility and accessibility to facilitate root-end procedures. • Biopsy is done for the histopathologic assessment of the pathologic soft tissue removed. • Technique – Place an appropriate size curette between the soft tissue mass and the lateral wall of the bony crypt. – Then apply pressure against the bone as the curette is inserted between the soft tissue mass and bone around lateral margins of lesion. – The soft tissue mass, if possible, can be removed from the bony crypt in one piece to facilitate periradicular curettage. – The curette detaches the soft tissue mass from the walls of the crypt, then a pair of tissue forceps can be used to grasp the soft tissue mass and immediately it is put in a bottle containing 10% buffered formalin solution and submitted for biopsy. – The curette is then used in scraping motion to remove the remaining soft lesion if any from the medial wall of the osseous defect.

Step 5: Management of Hemorrhage from the Surgical Site • Hemorrhage occurs during curettage and following root end resection which can obstruct vision and prevent careful evaluation of the root end and the further root end procedures. • Hemostasis can be achieved by: – Presurgical local anesthetics and vasoconstrictors – Use of local hemostatic agents in the surgical site. • Local hemostatic agents control hemorrhage from small blood vessels and capillaries by forming an occlusive clot, either by exerting a physical tamponade action or by enhancing the clotting mechanism. • Sponges or cotton pellets soaked in a vasoconstrictor such as racemic mixture of epinephrine hydrochloride can be used as a local hemostatic agent.

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• Local hemostatic agents can be classified as:

Step 6: Root End Management This step includes: • Root end resection and inspection of the resected root end • Conditioning of the root end • Preparing root end cavity to receive a filling. Root End Resection It involves resection of the apical 3 mm of the root apex so as to eliminate most of the apical ramifications and lateral canals that usually contain the irritant that contributes to periradicular disease. Thus it removes the etiologic agent of the disease. • Indications: – To eliminate anatomic variation. – To eliminate defects due to resorption. – In case of iatrogenic errors such as ledges, perforations, canal obstructions and separated instruments in the apical 1/3rd of the root. – In order to visualize the seal created by the orthograde root canal filling material. – In case of persistent periradicular disease. – Endodontic failure cases with irretrievable posts or obturating materials. • Objectives: – To remove the bacterial irritants, which are the most common etiologic agents of periradicular disease. – To remove the diseased periradicular tissue. – To prevent recontamination of periradicular tissues. – To allow remodelling of bone over the tooth structure by reducing apically fenestrated root apex below the level of surrounding cortical bone. • Extent of root end resection: Varies from case to case. Adequate access and visualization should be achieved. Factors determining extent of root end resection include: – Shape of the root – Number and location of canals within the root

– Extent of periradicular lesion – Root end filling material must be surrounded by sound dentin – Location of perforation, ledges, separated instruments – Associated periodontal factors – Level of crestal bone – Anatomic structures such as mental foramen or mandibular canal. • Angle of root-end resection: – Concept of beveling of root end as shown in Figure 26.8, which was described in the past, no longer stands true because it has been found that beveling of root end opens the dentinal tubules on resected root surface that may communicate with the root canal space resulting in apical leakage. - Earlier beveling was done to improve visibility. But with advent of DOM and microsurgical instruments, beveling of root end is not required. – Most appropriate angle of resection would be perpendicular (90˚) to the long axis of the root as shown in Figure 26.9. - Rationale for perpendicular root end resection: ■ Most likely to include all apical ramifications ■ It is convenient ■ It causes even distribution of stress forces exerted in apical region ■ Increasing the angle of root end resection causes decreased number of exposed dentinal tubules thus reducing chances of apical leakage.

Fig. 26.8  Beveling of root end

Surgical Endodontics

Fig. 26.9  Angle of resection should be perpendicular (90°) to the long axis of the root

Root End Conditioning • Resected root should be made smooth with a round bur in slow-speed contra-angle handpiece or the newly introduced miniature surgical handpiece, so that the surface cracks and anatomic variations are detected better. • Chemical treatment of the root end is called root condi­ tioning. Its purpose is to remove smear layer and to produce a conducive surface that allows for periodontal cell colonization without affecting the vitality of the adjacent periodontium. Root end conditioning can be done with solutions such as citric acid, tetracycline and EDTA, with citric acid being the most effective and commonly used agent. EDTA should not be used when MTA is going to be used as the root end filling material. Root end cavity preparation: A cavity is prepared to receive the filling. It is recommended that Class I cavity be prepared with a depth of about 3 mm and along the long axis of the tooth. Cavity preparation can be accomplished using micro­ handpiece with a rotating bur or ultrasonics. Root end cavity preparation using Ultrasonics: For root-end cavity preparation, specially designed ultrasonic tips are available. • Step-wise procedure: – Examination of the site using magnification and staining

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– Outline the cavity design by a sharp point of a CT-S ultrasonic tip, without irrigation – Deepen the prepared cavity design using appropriately sized and angled ultrasonic tip with irrigation. – Thoroughly irrigate the cavity with sterile saline. – Dry the cavity and examine under magnification. • Advantages of ultrasonics for root end cavity preparation: Ultrasonic root-end preparation has several advantages over the micro-handpiece method. – Less bone is removed and it produced conservative preparation – Decreased risk of root end perforation - No need for root-end beveling - More parallel walls for better retention – Less smear layer. • Disadvantages: Risk of root fractures from ultrasonic vibration. For bonded root end fillings, modified root end preparation includes a shallow, scalloped preparation of entire root surface about 1 mm at the deepest concavity. Root end cavity preparation for bonded root-end fillings (composites) requires a shallow, scalloped preparation of the entire root surface using a round or oval bur with a depth of atleast 1 mm at the deepest concavity. An ultrasonic preparation into the root canal system may not be necessary.

Step 7: Retrograde Filling Root end filling is done between the root canal space and the periradicular tissues. • Properties of an ideal root end filling material: – Should not be affected by moisture during setting – Should be biocompatible – Should be able to induce cementogenesis over the root end filling material and regeneration of PDL complex. – Should be dimensionally stable – Should be easy to handle – Should be insoluble in tissue fluids – Should be seen on radiograph (radiopaque) – Should produce a seal, preventing leakage – Should be nonstaining (Remember the alphabetic formula: ABCDEF S3) • Various root end filling materials: 1. Amalgam: Amalgam is most commonly used root end filling material. Amalgam is well-tolerated by periapical and periodontal tissues. It is readily available and easy to manipulate. However, amalgam

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used as a retrograde filling is not an ideal apical sealant. It is dimensionally unstable and may stain overlying soft tissues. 2. Zinc oxide eugenol cements: Zinc oxide powder and eugenol liquid mixed into a paste is compacted into a cavity preparation. Unmodified ZOE cements are weak, are soluble and have long setting time. Additions have been made to the basic ZOE mixture in order to increase the strength and radiopacity and to decrease the solubility of the final material. Intermediate restorative material (IRM) and super-EBA are commercially available ZOE materials. i. Intermediate restorative material (IRM): ■ Available as powder-liquid system ■ Powder contains: – 75% zinc oxide – 20% polymethacrylate ■ Liquid contains: – 99% eugenol – 1% acetic acid ■ Advantages: – Easy to place, has clay-like consistency on mixing powder and liquid – Well-tolerated by periradicular tissues – Seals well. ■ Disadvantages: No dental hard tissue regeneration potential. ii. Super-EBA: ■ This is also zinc oxide-eugenol based cement ■ Fast set and regular set are two forms ■ It also does not have cementum regeneration potential. 3. Mineral trioxide aggregate: Mineral trioxide aggregate (MTA) has been found to satisfy most of the criteria for a root end filling material. • Physical characteristics of MTA: – Available as fine, gray and white colored powders. Figure 26.10 shows photograph of commercially available packet of MTA. – It is mixed with saline or local anesthetic solution on a sterile glass slab – With the addition of more powder to liquid, the mix becomes too dry and crumbly – With addition of more liquid, it becomes too wet and runny, difficult to handle – Setting time of MTA is 2½ to 3 hours – Has pH of 10 initially and 12.5 about three hours after mixing.

Fig. 26.10  Commercially available MTA

• Consistency of mix for root end filling is recom­ mended to be firm, free of excess moisture. – It should not be too dry and crumbly – It should not be too wet and runny • MTA mix can be placed on the root end preparation using: – Small spoon excavator – Small amalgam-type carrier – Commercially available MAP system. • Drawbacks of MTA: – Difficult to handle (poor handling charac­ teristics) – Long setting time (2½–3 hours). 4. Composite resin system (Retroplast). ■ It is a two-paste, dual cure, dentin bonding composite resin system used in conjunction with a Gluma-based dentin bonding agent. ■ Working time of nearly 2 minutes. ■ Found to promote regeneration of periodontium with a cementum layer over the root end filling. ■ Requirements: While using composite resin as root end filling material: – There should be dry field – Optimum hemostasis. 5. Others: Glass ionomer cement, resin cements such as DIAKET have also been tried as root end filling material but with limited results. Appropriate root-end filling is placed in the prepared cavity on the root surface.

Surgical Endodontics

Fig. 26.11  Endodontic surgery—postoperative sequelae

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Step 8: Closure of Surgical Site • It is necessary to do careful visual and radiographic inspection of the surgical site before attempting closure of wound. • Evaluate radiographically: – To check for any root-end fragments present in surgical site – To check for any excess root-end filling material – To check the quality of seal achieved with the root end filling material. • If indicated, barriers such as resorbable or nonresorbable (Resorbable preferred for Endodontic surgery) membranes may be placed for the purpose of bringing about guided tissue regeneration (GTR) and guided bone regeneration (GBR). • The elevated mucoperiosteal flap is then gently repositioned back to its original position. • For approximation of incised tissues and to stabilize the reflected tissue during the initial phase of wound healing, sutures are placed using the appropriate technique. • Silk has been the commonly used suture material but since silk tends to support bacterial growth, patient should be advised to rinse with chlorhexidine mouthwash during the postoperative period. • Suture materials with Teflon coating, or synthetic monofilament suture material or gortex sutures have desirable properties for wound closure after periradicular surgery.

Postoperative Phase Possible Postoperative Sequelae These have been mentioned in Figure 26.11. Endodontic Surgery-Post-operative Sequelae (mnemonic to remember is: S2 H2 I3P3E).

Postsurgical Instructions • Postoperative pain can be managed well with NSAIDs such as Ibuprofen. • Patient is advised to do intermittent ice application (about 20–30 min each hour) in order to reduce pain and swelling. • Softer or semisolid room-temperature diet is recommended for 24 hours postsurgery. • Patient is advised to maintain the wound flushed and clean after meals. • Smoking is to be strictly avoided. • Patient is recalled for removal of sutures about 2–4 days following surgery. This is current concept so that all potential irritants from the incision area are removed as soon as possible. Earlier, it was recommended to wait for seven days after surgery before suture removal. • Patient is informed that minor oozing from surgical site causing pink tinge in saliva can be expected but if excessive bleeding occurs or if there is any event of emergency, then the patient should call up and inform the dentist immediately.

BIBLIOGRAPHY 1. Cohen S, Hargreaves KM. Pathways of Pulp, 9th Edn. St. Louis: Mosby, 2006.pp.724-71. 2. Grossman L, Oliet S, Del Rio C. Endodontic Practice, 11th Edn. Varghese publication, 1991.pp.289-311. 3. Ingle J, Bakland L, Baumgartner J. Ingle’s Endodontics, 6th Edn. BC Decker Inc, Hamilton, 2008.pp.1233-86.Aximi, utempor eptati conet abores entotatia voluptaesti siminci offici cus.

CHAPTER

27

Pulp Therapies

This chapter describes the various vital pulp therapy techniques—current concepts and materials used and also describes apexification.   You must know • What is Vital Pulp Therapy? • What are the Objectives of Vital Pulp Therapy? • What are the Techniques and Materials used for Vital Pulp Therapy? • What are the Hemostatic Agents and Antimicrobial Materials used in Vital Pulp Therapy? • What is the Criteria for Case Selection for Vital Pulp Therapy? • What is Apexification (Nonvital Pulp Therapy)?

WHAT IS VITAL PULP THERAPY? When the pulp tissue is affected directly or indirectly by caries, trauma or restorative procedures, the treatment carried out in order to preserve and maintain the pulp vitality is called vital pulp therapy. Preserving the vitality of the pulp is crucial to the tooth’s long-term survival and function of tooth as during life of the tooth, the healthy pulp produces reparative, secondary and peritubular dentin in response to various biologic and pathologic stimuli. Vital pulp therapy is the treatment consideration mostly in case of pulpally involved immature permanent teeth, where the preservation of radicular pulp tissue induces apexogenesis in teeth with open apices in order to retain the tooth as a functional unit. In pulpally involved tooth, this theory is based on the fact that pulp tissue has innate capacity for repair in absence of microbial contamination. In the last decade, lot of advances have occurred in the field of vital pulp therapy in terms of improved materials and techniques and expanded knowledge of pulp microbiology and caries progression. A new bioactive substance, mineral trioxide aggregate (MTA), has been found to potentiate the ability of dental pulp to heal, thereby retaining and maintaining its natural evolutionary function and purpose.

WHAT ARE THE OBJECTIVES OF VITAL PULP THERAPY? Figure 27.1 gives the objectives of vital pulp therapy (VPT).

WHAT ARE THE TECHNIQUES AND MATERIALS USED FOR VITAL PULP THERAPY?

Indirect Pulp Capping • Definition: Indirect pulp capping is defined as “a procedure in which a material is placed on a thin partition of remaining carious dentin that, if removed, might expose the pulp in immature permanent teeth”. (Ingle’s Endodontics, p.1312)

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• Materials used: – Calcium hydroxide – Zinc oxide eugenol • Rationale of indirect pulp capping: Rationale is based on the finding that when there exists a zone of demineralized affected dentin between the outer infected dentin and the pulp, infected dentin is removed and the affected dentin that is left behind remineralizes and the odontoblast form reactionary dentin, so that pulp exposure is avoided. Few viable bacteria that remain in the deeper layers of dentin are inactivated when cavity is sealed properly and pulp exposure prevented. Thus vitality of pulp is preserved. • Mechanism:

Fig. 27.1  Objectives of vital pulp therapy

• Objectives: – The interim or final restoration should seal completely the involved dentin from the oral environment – Vitality of tooth should be preserved – Absence of post-treatment signs or symptoms such as sensitivity, pain or swelling. – No radiographic evidence of internal or external root resorption or other pathologic changes. – Immature teeth with open apex should show continued root development and apexogenesis. • Indications: – Teeth with deep caries but free from symptoms of painful pulpitis – No spontaneous pain – No tenderness to percussion – No abnormal mobility – No radiographic evidence of radicular disease – No internal or external root resorption detectable radiographically. • Contraindications: – Teeth with deep caries with signs and symptoms of painful pulpitis – History of spontaneous pain – Tenderness to percussion – Abnormal mobility – Radiographic evidence of interradicular bone loss.

• Indirect pulp capping is not a predictable treatment option for permanent teeth due to following reasons: – Difficulty in determining at what depth, caries excavation should be halted. – As remineralization occurs, carious dentin becomes dry and loses volume that results in voids under the restorative material. – The dormant lesion may get rapidly reactivated in case of restoration failure. • Technique: First visit After profound anesthesia and isolation with rubber dam, Step 1: Large round bur #6 or #8 is used to excavate caries under adequate water cooling. Careful judicious use of spoon excavator can be made for caries excavation as its use in deep carious lesions may remove large segment of carious dentin.

Pulp Therapies

Step 2: C aries indicator dye is applied. Stained outer infected layers of dentin is removed. Unstained inner transparent layer is left intact. Step 3: All caries except that just overlying the pulp is removed and the remaining carious dentin (affected) is covered with zinc oxide eugenol or calcium hydroxide. Step 4: Tooth is sealed with hard setting ZOE or alternatively amalgam or acid etched bonded composite is placed to seal the tooth. Although use of permanent restoration at this stage is controversial. Second visit After about 6–8 weeks, tooth is reentered to confirm secondary or reactionary dentin formation and to excavate the remaining carious dentin without pulp exposure. Figures 27.2A to C are the diagrams showing steps of indirect pulp capping in mandibular first molar.

Direct Pulp Capping • Definition: Direct pulp capping is defined as, “treatment of an exposed vital pulp by sealing the pulpal wound with a dental material placed directly on a mechanical or traumatic exposure to facilitate the formation of reparative dentin and maintenance of the vital pulp”. (Ingle’s Endodontics, p.1312)

A

B

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• Objectives: – Vitality of tooth should be maintained – Absence of post-treatment clinical signs or symptoms of sensitivity, pain or swelling. – Pulp healing and formation of reparative dentin should occur. – No radiographic evidence of internal or external root resorption, periapical radiolucency, abnormal calcification or other pathologic changes. – Immature teeth with open apex should show continued root development and apexogenesis. • Indications: – Pinpoint (less than 0.5 mm in diameter) mechanical exposures surrounded by sound dentin produced as a result of caries removal during cavity preparation or due to trauma or during tooth preparation. – In teeth which are free from signs and symptoms of pulpitis. – Minimal or no bleeding from exposure site. – Exposure that has occurred in a clean, uncon­ta­ minated field. • Contraindications: – Large pulp exposures – Caries present surrounding the exposure site – Teeth with history of spontaneous pain

C

Figs 27.2A to C  Steps of indirect pulp capping: (A) Mandibular first molar showing deep occlusal and proximal caries approaching the pulp; (B) All caries is excavated except that is just overlying the pulp and is covered with calcium hydroxide sub-base and the tooth is sealed externally with hard-setting zinc oxide eugenol or amalgam may be placed as an interim restoration. a: Zinc oxide eugenol; b:  Calcium hydroxide sub-base; c: Affected dentin; d: Pulp horn; (C) After about 6–8 weeks the tooth is re-entered. Deposition of reactionary dentin is found beneath the caries that allows eradication of remaining caries without causing pulp exposure. Cavity preparation is completed and a fresh layer of calcium hydroxide is placed as sub-base, which is covered with zinc oxide eugenol or zinc phosphate base and a permanent restoration is placed. a: Permanent restoration; b: Pulp protecting base; c: Calcium hydroxide sub-base; d: Calcium hydroxide reacted affected dentin; e: Calcification seen overlying the pulp horn

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– Excessive bleeding indicating hyperemia or pulpal inflammation – Long standing pulp exposure that might have contami­nated with oral microorganisms. • Rationale of direct pulp capping: The remaining dental pulp with reversible pulpitis is selectively induced to produce a reparative barrier that protects the tissue from microbial challenges with the intention to postpone the more aggressive therapies, that could eventually lower the long-term prognosis for tooth retention and function. “Teeth undergoing orthograde root canal therapy and placement of posts and cores, followed by full coverage restorations, show lower long-term survival rates than teeth with vital pulps.” (Ingle’s Endodontics, p. 1313) • Materials used: – Ideal requirements of a pulp capping material: - Adhere to dentin and overlying restorative material - Bactericidal or at least Bacteriostatic - Caries prevention: Should prevent secondary caries by releasing fluoride - Dentin formation: Should stimulate reparative dentin formation - Easy to manipulate - Forces: Should be capable of resisting forces during restoration placement and under masticatory load - Should provide a tight Seal against bacteria - Should be Seen on radiographs (Radiopaque) (Remember the ideal requirements using Alphabetic formula ABCDEF S2). – Pulp capping materials:

• Can degrade and dissolve beneath restorations • Tunnel defects: Calcium hydroxide fails to provide a longterm seal against microleakage due to tunnel defects under the formed dentin bridge • Calcium hydroxide is available as: – Two pastes (Base and catalyst) - Dycal - Life - Care – Light cured system • Properties: – Mechanical: Low compressive strength Low tensile strength Low elastic modulus limit – Thermal: Calcium hydroxide provides some thermal insulation if it is placed in sufficiently thick layers. But usually it serves only as a sub-base and needs to be covered with a overlying base to provide thermal protection. – Solubility of Ca(OH)2 in water is high – Biological: - Pulpal Repair: Alkaline pH (9.2–11.7) that causes irritation of pulp tissue stimulating pulpal defense and repair - Secondary/Reparative dentin formation: Pulpal defense reaction and protein lysing effect results in reparative dentin formation. It has been found that due to tunnel defects in dentinal bridge associated with Ca(OH) 2, microorganisms can penetrate pulpal tissue and cause subsequent pulpal irritation. This is usually associated with pulpal calcification and canal obliteration. Figures 27.3A to C are the diagrams showing steps involved in direct pulp capping using calcium hydroxide.

Calcium Hydroxide Compounds • Calcium hydroxide has been widely used as a pulp capping agent since many years with variable treatment outcomes. • Have high alkaline pH that causes irritation of pulp tissue stimulating pulpal defense and repair • It is a relatively weak cement that may not be able to withstand forces • Associated with primary tooth resorption

A

B

C

Figs 27.3A to C  Steps of direct pulp capping: (A) Mandibular molar showing deep occlusal and proximal caries; (B) Caries excavation caused mechanical exposure of mesial pulp horn; (C) Calcium hydroxide placed as pulp capping agent, covered with pulp protective base and permanent restoration is done

Pulp Therapies

Zinc Oxide • • • •

Has obtundant effect on pulp Can provide protection against chemical insults Weak cement Does not have desirable properties of a pulp capping agent.

Adhesive Resins and Resin-modified Glass Ionomers • Their use as pulp capping agent is controversial. Some studies have shown favorable results with it. While other studies are associated with unfavorable reactions and lack of calcific bridge formation. • They have not been found to produce predictive pulpal healing, reparative dentin formation and elimination of microorganisms.

Mineral Trioxide Aggregate (MTA) • Introduced in Endodontics by Lee et al in early 1990s • Composition: Dicalcium silicate, tetracalcium alumino ferrite, calcium sulfate dehydrate, bismuth oxide • Available as: – White MTA powder (for esthetic reasons) – Gray MTA powder: Gray formulation has been found to give better results than white powder. • Desirable properties of MTA making it suitable as pulp capping agent: – MTA is hygroscopic and sets in the presence of moisture, so even if there is contact with tissue fluids or blood, it does not affect its properties – Good marginal adaptation – Forms a reactionary layer at the dentin interface resembling hydroxyapatite in structure – High alkaline pH of 12.5, which is sustained, with slow release of calcium, arrests any further microbial growth of residual microorganisms that may be left after caries excavation. Also, slow release of calcium ions allows material to stimulate growth factors from the dental pulp and promote signalling molecules such as interleukin, TGF-Beta for hard tissue formation. – Due to small particle size, it produces gap-free interface. As a result, microleakage and bacterial ingression is prevented. – MTA has high compressive strength and surface texture of set cement is favorable to withstand stresses and provide strong bonding with adhesive restorations. – MTA fulfils most of the ideal requirements of a pulp capping material.

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• Clinical procedure with MTA: (Two-visit procedure) Refer Figures 27.4A to F for steps of direct pulp capping using MTA. First Visit After profound anesthesia and isolation of tooth with rubber dam, Step 1: Caries removal under magnification. Caries detector dye is applied for 10 seconds and then tooth is washed and dried. Slow speed round carbide burs and spoon excavator used to excavate the stained carious dentin. Then again apply caries detector and check and excavate till no stain or only light stain evident. Step 2: During caries removal, if pulp exposure occurs, achieving hemostasis at exposure site by placing cotton pellet moistened with 3–6% sodium hypochlorite for 20–60 seconds. Again staining and careful removal of remaining caries around exposure site till no staining visible. After caries excavation, if still there is bleeding from the exposure site then cotton pellet moistened with 3–6% NaOCl is placed directly on exposure site for 1–10 minutes. If even after 10 minutes, hemostasis cannot be achieved, then diagnosis of irreversible pulpitis is made and pulpotomy or pulpectomy procedure recommended. Step 3: MTA is mixed to consistency of wet sand and gently patted down with moist cotton pellet over the exposure site as well as on the surrounding dentin of pulpal roof or axial wall in the thickness of atleast 1.5 mm. Step 4: Place a moist cotton pellet over MTA and let it remain there and place interim restoration over it. Second Visit Schedule after 5–10 days. Ask patient for symptoms. Perform pulp vitality testing. Isolate the tooth, remove the interim material and cotton pellet. Confirm that MTA has set. Then, permanently restore the tooth with bonded composite. Occlusion is adjusted and patient is recalled at 6 weeks and subjective symptoms evaluated and radiograph taken. Subsequent follow-up after 6 and 12 months. One-visit Procedure with MTA After profound anesthesia and isolation of tooth with rubber dam, Step 1: Caries is excavated under constant water cooling and magnification. Step 2: Hemostasis at the exposure site is achieved using cotton pellet moistened in 2.6–5% NaOCl. Step 3: Prepare Proroot MTA and apply on exposure site and use cotton pellet to remove excess moisture.

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A

B

C

D

E

F

Figs 27.4A to F  Steps of two-visit direct pulp capping using MTA in a young permanent tooth. First visit: (A) Deep caries in permanent molar tooth excavated, small (pin-point) exposure of pulp causing bleeding; (B) Cotton pellet moistened with 3–6% NaOCl is placed directly on exposure site for 1–10 minutes; (C) MTA mixed to consistency of wet sand of about 1.5 mm thickness is gently patted down with moist cotton pellet over the exposure site as well as on the surrounding dentin of pulpal roof or axial wall; (D) A moist cotton pellet is placed over MTA and covered with an interim restoration. Second visit: (E) Interim restoration and cotton pellet removed and a probe is used to confirm that MTA has set; (F) The tooth is permanently restored with composite restoration

Step 4: Place a lining of light cured GIC liner over MTA. Step 5: Place bonded composite restoration in the same visit. Patient is recalled and checked after 3–6 months.

Pulpotomy • Definition: Pulpotomy is defined as “the surgical removal of the coronal portion of a vital pulp as a means of preserving the vitality of the remaining radicular portion” (Ingle’s Endodontics, p. 1312). • Objectives: – Preservation of vitality of radicular pulp – Relief of pain in patients with acute pulpalgia – To promote apexogenesis in immature permanent tooth

• Rationale: Surgical excision of coronal pulp ↓ Inflamed and infected area is removed ↓ Leaving behind vital, uninfected pulpal tissue in the root canal ↓ Remaining pulp may undergo repair while completing apexogenesis (Root end development and calcification) in young permanent immature tooth. (Also, removal of inflamed portion relieves pulpalgia.) ↓

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Medicament placed over the pulp stump induces necrosis, beyond which undifferentiated mesenchymal cells or fibroblasts in cell-rich zone differentiate into odontoblast ↓ Odontoblast produce reparative dentin ↓ “Bridge” forms to cover and protect the pulp • Indications: Pulpotomy is indicated in pulpally involved immature young permanent tooth. Teeth with healthy, hyperemic or slightly inflamed pulps such as: – Traumatic exposure: Young permanent anterior tooth with wide open apex that is fractured during sports or accident – Carious exposure: Posterior tooth with wide open apices that has small, asymptomatic carious exposure. • Contraindications: – Abnormal sensitivity to heat and cold – Chronic pulpagia – Irreversible pulpitis – Necrosis of pulp – Calcification in pulp chamber – Extension of pulpal disease into periapical tissues causing periradicular disease – Tenderness of tooth to palpation or percussion • Types of pulpotomy: Based on the amount of pulp tissue removed: Partial pulpotomy and complete pulpotomy.

Partial Pulpotomy Also called as Cvek pulpotomy • Definition: Partial pulpotomy is defined as “the surgical removal of a small portion of vital pulp as means of preserving the remaining coronal and radicular pulp”. (Ingle’s Endodontics, p.1313) • It is similar to direct pulp capping with only difference that some inflamed pulp tissue is removed • It is indicated in carious or traumatic exposures when the pulp is vital and only 1–2 mm of coronal pulp tissue is inflamed. • Only about 2–3 mm of superficial inflamed pulp is excised and a biocompatible material such as calcium hydroxide is placed over it. • Glass ionomer lining can be put and the tooth is restored with permanent restoration such as composite resin. Figure 27.5 shows diagrammatic representation of partial pulpotomy.

Fig. 27.5  Partial pulpotomy in a permanent maxillary central incisor tooth

Complete/ Cervical Pulpotomy • Similar to partial pulpotomy, just that in cervical pulpotomy, entire coronal pulp to the level of the root orifices is excised. • The coronal pulp is completely removed and the suitable material is placed over the canal orifices. • In case of mature permanent teeth, pulpotomy is used as the means of relieving pain during an emergency appointment of severe pain due to irreversible pulpitis. Pulpectomy and completion of root canal treatment procedure can be done in the subsequent appointment. Based on the mode of action of medicament used: Type

Materials

Devitalization

Formocresol Electrocoagulation Ca(OH)2 Enriched collagen Hard setting Ca(OH)2 Freeze dried bone Demineralized dentin BMP OP MTA ZOE Gluteraldehyde Ferric sulfate Laser

Regeneration

Preservation

Formocresol Pulpotomy It is usually done in case of pulpally involved primary teeth in which there is inflammation only in the coronal pulp or

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mechanical exposure cases. Coronal pulp up to the root canal orifices is extirpated, bleeding is controlled by pressure and then a cotton pledget moistened with formocresol is applied for about five minutes which is covered with zinc oxide eugenol cement base and then restored with amalgam or glass ionomer restoration. Formocresol causes necrosis and fixation of tissue and is a potent antibacterial substance. Steps involved in formocresol pulpotomy procedure in a deciduous molar are demonstrated and explained in Chapter 28 Pediatric Endodontics.

Calcium Hydroxide Pulpotomy Calcium hydroxide has been widely used in vital pulp therapy in permanent tooth due to its has antibacterial property and ability to form hard tissue barrier. It has an alkaline pH of 11. Coronal pulp is amputed to the level of root canal orifices, hemorrhage is controlled and calcium hydroxide mixed with water or commercially available paste containing calcium hydroxide in combination with other medicaments is applied on the amputed pulp which is covered with zinc oxide eugenol cement and then sealed with a permanent restoration. Necrosis occurs under the placed calcium hydroxide, beyond which a reparative dentinal bridge is formed. A radiograph is taken for future comparison to check the calcific bridge formation after three months. A tooth treated with calcium hydroxide pulpotomy may develop internal resorption or calcification of the root canal which also should be monitored on subsequent radiographs and Endodontic therapy should be performed as soon as apexogenesis is completed and is evident radiographically.

Mineral Trioxide Aggregate Pulpotomy Pulpotomy can be an effective procedure in deciduous teeth and young permanent teeth when MTA is used due to its desirable properties mentioned before, such as alkaline pH (10.2–12.5), antibacterial agent, pulp underneath has less inflammation. It forms a dentinal bridge that is thicker and continuous unlike calcium hydroxide. MTA mix contains calcium oxide which comes in contact with moisture to form calcium hydroxide and induces the hard calcific bridge through the same mechanism as calcium hydroxide.

adequate to achieve hemostasis. Various hemostatic and antimicrobial agents include: • Ferric sulfate disinfectant (Consepsis-Ultradent product) • Epinephrine • Hydrogen peroxide • Sodium hypochlorite (NaOCl): It is safe and most practical method to achieve hemostasis in vital pulp therapy. Besides excellent hemostasis, it removes most of the dentinal chips as well as the biofilm and thus brings about disinfection of the cavity interface. It also removes the damaged cells from mechanical or traumatic exposure. • MTAD (Mixture of Tetracycline isomer doxycycline, citric Acid and Detergent): MTAD has been tried and favourable results achieved.

WHAT IS THE CRITERIA FOR CASE SELECTION FOR VITAL PULP THERAPY? • Age of patient: In case of young patients with initial caries on first molars causing reversible pulpitis, direct pulp capping can be done. Favorable prognosis for vital pulp therapy diminishes with increasing age of the patient. • Rate of decay: In case of patient with rampant caries, pulpotomy will be preferred over pulp capping as patient may have recurrent caries. • Remaining tooth structure: If there is advanced caries and severe coronal breakdown that may need full coverage restoration, pulpotomy rather than direct pulp capping is recommended. • History of restorative treatment: In case of mature permanent teeth, teeth with no previous history of restorative treatment, direct pulp capping can be done. • Pulp hemorrhage: Visualize the pulp and assess the hemorrhage. If bleeding can be controlled with 3–6% NaOCl applied with cotton pellet on exposed pulp for about 1–10 minutes, then direct pulp capping can be done. But if bleeding cannot be controlled, then diagnosis of irreversible pulpitis is made and pulpotomy or pulpectomy may have to be done. • Irreversible pulpitis in immature permanent tooth: In young permanent teeth with open apices, pulpectomy is done and MTA is used as a root end plug to promote root end closure.

WHAT IS APEXIFICATION (NONVITAL PULP THERAPY)?

WHAT ARE THE HEMOSTATIC AGENTS AND ANTIMICROBIAL MATERIALS USED IN VITAL PULP THERAPY?

Apexification

Direct pressure at the exposure site with cotton pellet moistened in sterile water or saline may be sometimes

• Definition: “Apexification is a method to induce development of the root apex of an immature, pulpless

Pulp Therapies

tooth by formation of osteocementum or other bone-like tissue” (Grossman’s Endodontic Practice, 11th Edition, p. 110). According to American Association of Endodontists, “Apexification is a method to induce a calcific barrier in a root with an open apex or the continued apical development of an incomplete root in tooth with necrotic pulp.” Apexification procedure involves debridement of canal, short of the apex, without disturbing apical tissues and placement of a biocompatible material to stimulate hard tissue formation. Open apex of an immature permanent tooth is also called ‘blunderbuss apex’. Apexogenesis is the physiologic process of root development whereas apexification is induced root end development using a biocompatible material. • Objective: – Induce closure of the open apical third of the root canal – Formation of an apical barrier, creating an apical stop, against which obturation can be achieved. – Preserve and stimulate Hertwig’s epithelial root sheath (HERS), to induce root end development by natural root lengthening process. • Rationale: –

Any viable and undamaged apical pulp tissue present in the root canal along with the odontoblastic layer associated with the pulp tissue is preserved ↓ Cleaning and shaping/disinfection of the root canal 2 mm short of the radiographic apex to remove microorganisms and toxic products without causing any harm to the viable pulp tissue and HERS ↓ Matrix formation and subsequent calcification guided by viable HERS, creating an apical stop, against which  dense obturation can be achieved. (Refer Figure 27.6A) – If necrotic pulp and destroyed HERS, ↓ Disinfection of root canal 2 mm short of root apex ↓ Biocompatible material used as chemical stimulant to induce differentiation of cementoblast or undifferentiated fibroblasts of periapical tissue and periodontal ligament ↓ A hard substance forming a calcific bridge at or short of apex, creating an apical stop, against which dense obturation can be achieved. (Refer Figure 27.6B)



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Histologically, the hard substance formed may have configuration either of bone, dentin, osteodentin or cementum

• Materials used: Calcium hydroxide, mineral trioxide aggre­ gate (MTA), Radiopaque calcium hydroxide paste in a methylcellulose base, calcium hydroxide in combination with Camphorated paramonochlorophenol, zinc oxide paste, etc. • Technique: – Using calcium hydroxide: - Anesthesia may or may not be needed. Isolation of tooth with rubber dam. Access preparation and coronal pulp extirpation - Preoperative radiograph used to determine apparent length of the tooth and instrumentation done 2 mm short of the apex to remove necrotic pulpal tissue and prepare the root canal for calcium hydroxide dressing. - Root canal is dried with blunt absorbent points - Calcium hydroxide is mixed with sterile water or anesthetic solution to a thick consistency and carried to the pulp chamber using amalgam carrier with plastic tips and then thick, large finger plugger is used to force the dry calcium hydroxide paste into the root canal. Alternatively, rotating lentulospiral can be used to deliver the calcium hydroxide paste into the root canal. - A radiograph is taken to confirm the correct placement of the medicament. Care should be taken to avoid pushing it beyond the apex. - Temporary coronal seal: A dry cotton pellet is placed over the material and sealed with reinforced zinc oxide eugenol cement. - Recall: Patient is recalled after 3 months and radiograph is taken to check if calcific barrier is formed at or near apex. If it is not formed, then old calcium hydroxide dressing from the root canal is removed using large files and copious irrigation with sterile water or normal saline to prevent irritation to periapical tissues. Patient is recalled every 3 months till radiographic evidence of an apical barrier is seen that denotes apexification. It has been found that this process takes about 3 months to 21 months. - Once the apical stop is created, obturation of the canal with gutta-percha is done.   Figure 27.7 shows the diagrammatic representation of apexification procedure using calcium hydroxide.

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B

Figs 27.6A and B  Successful outcome of apexification. (A) Root end development; (B) Calcific bridge is formed

A

D

Fig. 27.7  Apexification using calcium hydroxide

– Using mineral trioxide aggregate: MTA is considered material of choice for apexification because it is found to create permanent apical plug at the outset of treatment. - Anesthesia may or may not be needed. Isolation of tooth with rubber dam. Access preparation and coronal pulp extripation - Preoperative radiograph used to determine apparent length of the tooth and instrumentation and irrigation done 2 mm short of the apex to remove necrotic pulpal tissue and to prepare the root canal. - Root canal is dried with blunt absorbent points

B

C

E

Figs 27.8A to E  Apexification procedure using MTA. (A) a: Necrosed pulp, b: Open apex (blunderbuss); (B) Instrumentation done 2 mm short of apex; (C) Apical plug of MTA and a moist cotton pellet is placed in pulp chamber and sealed with a temporary cement. ‘a’ shows MTA apical plug; (D) Apical barrier formed is checked using an Endodontic instrument such as plugger or spreader after 48 hours against which obturation is achieved; (E) Outcome after 3–6 months: a: Calcified bridge, b: Obturation of canal using gutta-percha, c: Permanent restoration

- Mineral trioxide aggregate (MTA) is mixed with distilled water as per manufacturer’s instructions and placed as an apical plug in the apical 3–4 mm using a special plugger or amalgam carrier. - Radiograph is taken to verify the placement - MTA sets under moisture. So, a moist cotton pellet is placed in the pulp chamber and access is sealed using reinforced zinc oxide eugenol cement.

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- Recall: Patient is recalled every 3 months to check the apical barrier formation radiographically. Figures 27.8A to E shows diagrammatic representation of apexification using MTA. Figures 27.9A and B show radiograph of pulpally involved immature permanent maxillary central incisor tooth in which MTA was used for apexification and obturation completed with gutta-percha. Also, one more case of immature pulpally involved maxillary right central incisor, in which apexification was done is explained in Chapter 24: Management of Dental Traumatic Injuries (Figs 24.9A to D). A

B

Figs 27.9A and B  (A) Radiograph showing immature pulpally involved permanent maxillary right central incisor; (B) The case was completed with an apical plug of MTA for apexification and guttapercha root canal filling in the same tooth (Courtesy of Dr Chetan Shah)

- After two days, hardening of MTA is checked gently and obturation with gutta-percha is done.

BIBLIOGRAPHY 1. Cohen S, Hargreaves KM. Pathways of Pulp, 9th edn. St. Louis: Mosby, 2006.pp.834-82. 2. Grossman L, Oliet S, Del Rio C. Endodontic Practice, 11th edn. Varghese publication, 1991.pp.102-15. 3. Ingle J, Bakland L, Baumgartner J. Ingle’s Endodontics, 6th edn. BC Decker Inc, Hamilton, 2008.pp.1310-29. 4. Reference Manual, V 36/No 6, 14/15, AAPD, ‘Guideline on Pulp Therapy for Primary and Immature Permanent Teeth’.

CHAPTER

28

Pediatric Endodontics

This chapter explains the specific features of the Pediatric patients that may require special considerations during Endodontic treatment and describes the various pulp therapies that can be performed in Pediatric patients.   You must know • What is Pediatric Endodontics? • What are the Objectives of Preserving Primary Teeth? • What are the General Features of Endodontic Treatment of Pediatric Patients? • What are the Specific Morphologic Features of Teeth of Pediatric Patients? • How to Establish a Correct Pulpal Diagnosis in Children? • What is the Important thing you must know about the Proximal Lesions in Primary Teeth? • Which are the Different Pulp Therapies Performed in Children? • Pulp Therapies for Primary Teeth

WHAT IS PEDIATRIC ENDODONTICS? Endodontic treatment performed in children for the preservation of primary and young permanent teeth with pulp involvement to prevent premature loss of primary teeth and to facilitate completion of development of young permanent teeth to render them functional for many years, is called Pediatric Endodontics.

WHAT ARE THE OBJECTIVES OF PRESERVING PRIMARY TEETH?

• Primary teeth have complex root canal anatomy. • During Endodontic treatment of primary teeth, there is danger of injury to permanent tooth bud. • There can be special problems associated with the natural resorption of primary tooth roots.

WHAT ARE THE SPECIFIC MORPHOLOGIC FEATURES OF TEETH OF PEDIATRIC PATIENTS? We shall discuss these features by classifying them in the following way:

Objectives of preserving primary teeth include (Fig. 28.1).

WHAT ARE THE GENERAL FEATURES OF ENDODONTIC TREATMENT OF PEDIATRIC PATIENTS? • During treatment of pediatric patients, aspects of child psychology and behavior management have to be considered which can be time-consuming and sometimes challenging too.

Fig. 28.1  Objectives of preserving primary teeth

Pediatric Endodontics

• Specific morphologic features of primary teeth (Fig.  28.2A): – Crown: - Enamel: Enamel is thinner and more consistent in thickness when compared to permanent teeth. - Dentin: The thickness of dentin between the enamel and the pulp chamber is less and does not provide much protection to large pulp. - Pulp chamber: Larger pulp chamber in relation to overall size of tooth crown and in comparison to permanent teeth. Pulp horns, especially mesial pulp horns are higher in primary molars as compared to permanent molars. - Wider mesiodistal dimension of crowns in comparison with their crown length than crowns of permanent teeth. - Marked constriction at the dentinoenamel junction (DEJ) as compared to permanent teeth. - Narrower occlusal surface in the faciolingual direction due to converging facial and lingual surfaces occlusally of primary molars. – Root: - Flaring (diverging) root of primary molars from the cervix and more at the apex. - Longer and more slender roots of primary molars as compared to permanent molars. - Narrower and longer roots as compared to crown length and width. So, root-to-crown length of primary teeth is greater than that of permanent teeth. - Root length completion occurs in shorter period of time than the permanent teeth due to shorter length of primary roots. - Resorption of roots begins soon after root length completion and there is deposition of additional dentin within the root canal system that significantly changes the number, size and shape of the root canals within the primary tooth. • Specific morphologic features of young permanent teeth (Fig. 28.2B):

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– Crown: Important consideration is relatively larger pulp chambers and high pulp horns as compared to adult teeth. – Root: Apical root development may be incomplete causing presence of blunderbuss canals. If pulp necrosis occurs prior to complete dentin deposition there would be thin roots which are more prone to fracture. – An immature nonvital young permanent tooth will have poor crown to root ratio. In case of a pulpally involved young permanent tooth, efforts are directed towards stimulation of reparative dentin to retain the tooth as functional unit. Additional procedures such as apexification may be necessary for maintaining pulpless immature permanent tooth. • Specific features of primary root canal anatomy of individual teeth: – Maxillary primary incisors (Fig. 28.3): - Single round root canal resembling the shape of the root. - Permanent tooth bud lies lingual and apical to primary tooth, so resorption is initiated on the lingual surface in apical third of roots. – Mandibular primary incisors (Fig. 28.4): - Single root canal flattened on mesial and distal surfaces - Occasionally, two canals may be present - Lateral or accessory canals may be present. - Permanent tooth bud lies lingual and apical to primary tooth. So resorption is initiated on the lingual surface in apical third of roots.

A

B Figs 28.2A and B  Shows the diagrammatic representation of primary (A) and young permanent tooth (B)

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Fig. 28.3  Maxillary primary incisor

Fig. 28.4  Mandibular primary incisor

Fig. 28.5  Maxillary and mandibular primary canine

– Maxillary and mandibular primary canines (Fig. 28.5): - Single rounded root canal corresponding to exterior root shape. - Triangular shape of root canal with the base towards the facial surface. - Bifurcation of canal or lateral canals generally not present. - Permanent tooth bud lies lingual and apical to primary tooth, so resorption is initiated on the lingual surface in apical third of roots – Maxillary first primary molar (Fig. 28.6): - Two to four canals are present that correspond to exterior root form with much variation. - Palatal root is usually round and longer than the facial roots. - In about 75% of maxillary first primary molar, there is bifurcation of mesiofacial roots into two canals. - The isthmus connecting separate canals is narrow and islands of dentin exist between the canals with many connecting branches. - Mesial canal tends to show variations - Accessory canals, lateral canals and apical ramifications of pulp may be present. – Maxillary second primary molar (Fig. 28.7): - Two to five canals are present that correspond to exterior root form. - Mesiofacial root usually bifurcates or it may contain two distinct canals. - Fused palatal and distofacial roots may have a common canal or a narrow isthmus connecting separate canals may be present with island of dentin between canals with connecting branches. – Mandibular first primary molar (Fig. 28.8): - Usually 3 canals are present corresponding to external root anatomy but may have two or four canals. - Approximately, 75% of mesial roots have two canals and 25% of distal roots contain more than one canal. - Accessory canals, lateral canals and apical ramifications of pulp may be present. - Resorption begins on inner surface of roots next to interradicular septum causing variations in root canal anatomy – Mandibular second primary molar (Fig. 28.9): - Usually three canals are present. But, two to five canals may be present. - Mesial root tends to show variations.

Pediatric Endodontics

Fig. 28.6  Maxillary first primary molar

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Fig. 28.9  Mandibular second primary molar

- Accessory canals, lateral canals and apical ramifications of pulp may be present. - Resorption begins on inner surface of roots next to interradicular septum causing variations in root canal anatomy.

HOW TO ESTABLISH A CORRECT PULPAL DIAGNOSIS IN CHILDREN? History Taking

Fig. 28.7  Maxillary second primary molar

• A thorough medical history to evaluate child’s general condition is important. In a child with systemic disease, Endodontic therapy may be contraindicated or may require different approach. • Pain history: In case of pediatric patients, history of pain given by child or his parents sometimes, may not be relied on completely. But, still few direct questions related to pain such as onset, duration, intensity, nature of pain, etc. can be very useful indications of the status of the pulp.

Clinical Examination

Fig. 28.8  Mandibular first primary molar

• Careful inspection and palpation of oral soft and hard tissues. Figure 28.10 shows multiple carious deciduous teeth in a child. (Nursing bottle caries) Figure 28.11 shows photograph of trauma to permanent anterior teeth in a child. • Intraoral sinus opening and draining sinus tracts are quite common in children due to early involvement of pulp.

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Most of the times, an accurate pulpal diagnosis is established only after direct evaluation of pulp tissue. One has to check for: • Size of exposure: It may be pinpoint or massive carious expo­sure associated with varying degrees of pulpal inflammation. • Amount of hemorrhage: Tooth with extensive inflammation may bleed profusely when pulp amputation is done. There is persistence of bleeding for long, even after pressure with cotton pellet is applied for hemostasis. • Pulp polyp: Chronic inflammation of pulp in the form of pulp polyp may be seen.

Fig. 28.10  Nursing bottle caries involving all maxillary teeth and mandibular posterior teeth in a child (Courtesy of Dr Samir Khaire)

Fig. 28.11  Trauma to permanent anterior teeth in a child (Courtesy of Dr CR Suvarna)

• Percussion test may not be very reliable because it depends on subjective response by the child. • Mobility test also may not be very reliable because of the aspect of normal physiologic mobility of primary teeth associated with natural resorption of roots.

Pulpal Diagnostic Tests Thermal tests and electric pulp test are generally unreliable in children due to some aspects of pulpal anatomy of primary teeth and due to other problems in children related to apprehension and management.

Radiographic Examination Intraoral periapical (IOPA) and bitewing radiographs of the affected area has to be taken. On the radiograph: • Extension of caries can be seen. Figure 28.12 is radiograph showing pulpally involved immature tooth with open apex. • Physiologic root resorption of primary teeth may be apparent. • Developing permanent tooth buds are seen • Calcified masses may be seen in pulp chamber in response to irritation to pulp • Radiolucency may be apparent in the bifurcation or trifurcation of roots rather than at the apex due to presence of accessory canals on pulpal floor or communication from necrotic pulp to furcation through altered dental tissue in area of furcation. Figure 28.13 is radiograph showing radiolucency in the furcation and around the roots of an over-retained deciduous molar. • Pathologic root resorption and bone resorption may be present due to extensive inflammation in the tooth. • Internal root resorption due to pulpal pathosis may be seen. • Follow-up of treatment: Radiographs of treated teeth are taken during the follow-up visits to evaluate the outcome of treatment. Figure 28.14 shows few examples of posttreatment and follow-up radiographs. A panoramic view is also very valuable radiograph in Pedodontics as it shows in one view all the deciduous teeth along with the permanent tooth buds so that proper treatment can be planned. Figure 28.15 shows a panoramic image of a patient. After proper history taking and thorough clinical and radiographic examination, or sometimes after direct

Pediatric Endodontics

Fig. 28.12  Radiograph showing pulpally involved immature tooth with open apex (Courtesy of Dr Chetan Shah)

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Fig. 28.14  Few examples of post-treatment and follow-up radiographs (Courtesy of Dr Ashwin Jawdekar)

Fig. 28.15  Panoramic image (commonly referred to as orthopantogram) (Courtesy of Dr Ashwin Jawdekar) Fig. 28.13  Over-retained deciduous molar (Courtesy of Dr Chetan Shah)

evaluation of pulp tissue, pulpal diagnosis can be made such as: – Reversible pulpitis – Irreversible pulpitis – Pulp necrosis • Important considerations for deciding treatment – Affected tooth: Time of exfoliation with respect to dental age of patient. – Restorability of crown – Presence or absence of permanent successor – Extent of infection: Whether the infection is severe enough that has the potential to affect permanent tooth bud or that cannot be treated with Endodontic therapy and will need extraction.

A mind-map to remember pulpal diagnosis in children is given in Figure 28.16.

WHAT IS THE IMPORTANT THING YOU MUST KNOW ABOUT THE PROXIMAL LESIONS IN PRIMARY TEETH? Proximal lesions in primary teeth are quite deceptive. One must consider appropriate pulp therapy in the event of: • Lesions extending subgingivally • Lesions with marginal ridge breakdown • Lesions with the involvement of more than 50% of tooth substance from the outer margin towards pulp as evident on radiograph. Proximal lesions without gingival seat are difficult to restore and endanger pulp exposure.

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Fig. 28.16  A mind-map to remember pulpal diagnosis in children

Dentin of primary teeth has wider tubules. As a result there is rapid progress of caries. There is possibility of invasion of bacteria and their toxins much before frank carious exposure. Moreover apart from stainless steel crown, it may not be possible to seal the margins adequately. Thus a conservative approach in management of pulpal lesions may not help. Therefore, pulp therapies such as indirect pulp capping or pulpotomy needs to be considered for all deep proximal lesions.

Another factor that needs to be considered is the dental age of the patient. If the dental age is more, then a conservative approach is preferred. If dental age is lesser, then more definitive pulp therapies such as pulpotomy or pulpectomy needs to be done. It is needless to state that proximal lesions will need adequate coronal seal and stainless steel restoration would be the restoration of choice in most instances. Figures 28.17A to C show the photographs and corres­ ponding radiographs of proximal lesions in various primary teeth.

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A

B

C Figs 28.17A to C  Proximal lesions in primary teeth. (A) Maxillary posterior region; (B) Mandibular posterior region; (C) Maxillary anterior region

WHICH ARE THE DIFFERENT PULP THERAPIES PERFORMED IN CHILDREN? In children, pulp therapies may be performed in primary teeth or in young permanent teeth generally with open

apices. The latter have been discussed in Chapter 27: Pulp Therapies and in Chapter 24: Management of Dental Traumatic Injuries. Here we will discuss about the pulp therapies for primary teeth.

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Indirect Pulp Capping

PULP THERAPIES FOR PRIMARY TEETH Protective Liner It is a thinly-applied liquid which is placed on the pulpal surface of a deep cavity preparation covering the exposed dentinal tubules, to act as protective barrier between the restorative material and the dental pulp. Examples of protective liner include: Calcium hydroxide, dentin bonding agent, glass ionomer cement. • Indications: In a tooth with normal pulp, after excavation of all the caries, a protective liner may be placed in the deep areas of the preparation in order to: – Minimize injury to the pulp and promote pulp tissue healing – Reduce postoperative sensitivity. • Objectives: Liner is placed in deep area of the cavity preparation: – To promote pulp tissue healing, – To promote formation of tertiary dentin – To preserve pulp vitality – To minimize bacterial microleakage.

Done in case of deep carious lesion approximating the pulp, where it is anticipated that pulp would be exposed when caries is excavated. This should be done only when there are no signs or symptoms of irreversible pulpitis. • Indications: Deep carious lesion in a primary tooth with no signs of pulp degeneration. • Contraindications: – Signs or symptoms of irreversible pulpitis – Radiographic lesion such as internal or external resorption or furcation radiolucency • Objectives: – The restorative material seals the involved dentin from the oral environment. – Vitality of the tooth preserved – No post-treatment clinical signs or symptoms such as sensitivity, pain or swelling. – No radiographic evidence of pathologic external or internal root resorption or any pathologic change. – No harm to the succedaneous tooth. • Technique: – Anesthesia and rubber dam isolation. – Excavation of caries using a round bur except that directly overlying the pulp. Spoon excavator can be used for excavation in deep cavities, but should be used judiciously if indirect pulp capping is planned, as it might remove large segment of caries causing direct exposure of pulp. – A biocompatible material such as calcium hydroxide or zinc oxide eugenol is placed over remaining carious dentin to stimulate healing and repair. If calcium hydroxide is used, then it should be covered with glass ionomer or reinforced zinc oxide/ eugenol material is placed over it to provide a seal against microleakage as calcium hydroxide has high solubility, poor seal and low compressive strength. – The tooth is then restored with hard-setting, reinforced ZOE or amalgam or acid-etched bonded composite to seal it against microleakage – The tooth re-entered after a period of approximately 6 weeks and removal of remaining caries is done. This remaining caries generally appears dehydrated, slightly hard consistency and light brown color. According to current literature, there is no conclusive evidence that it is necessary to reenter the tooth to remove residual caries so long as the tooth remains sealed from bacterial contamination and shows good prognosis for caries arrest and reparative dentin formation to protect the pulp. – The re-entered tooth is then permanently restored. (with Glass ionomer or amalgam restoration)

Pediatric Endodontics

Direct Vital Pulp Therapies Direct Pulp Capping Done in case of traumatic or mechanical pulp exposures. • Indications: Pin-point sized mechanical or traumatic pulp exposure, when the pulp is vital and no signs or symptoms of irreversible pulpitis. Direct pulp capping of a carious pulp exposure in a primary tooth should not be done. • Contraindications: – Carious pulp exposure – Large exposures – Profuse bleeding from exposure site indicating extensive inflammation • Material used: Calcium hydroxide is the pulp capping agent of choice. MTA can also be used. • Objectives: – Vitality of the tooth preserved – No post-treatment clinical signs or symptoms such as sensitivity, pain or swelling. – Healing of pulp and reparative dentin formation should occur. – No radiographic evidence of pathologic external or internal root resorption or any pathologic change. – No harm to the succedaneous tooth. • Technique: – Anesthesia and rubber dam isolation – Excavation of caries with bur or spoon excavator, if it causes mechanical or traumatic pulp exposure which is pin-point sized and no bleeding or minimal bleeding occurs, then pressure with cotton pellet is applied to control bleeding. – Calcium hydroxide is placed over the exposed pulp. It is covered with glass ionomer or reinforced zinc oxide/eugenol material as base and the tooth is permanently restored with amalgam or composite restoration. It is recommended that direct pulp capping be performed in older children in cases in which the teeth will exfoliate within 1 or 2 years.

Pulpotomy in Primary Teeth Amputation of the coronal pulp leaving behind vital radicular pulp is done in cases of carious pulp exposures or large traumatic exposures, in which the inflammation is confined to the coronal pulp. • Indications: Carious pulp exposure in primary teeth or inflammation of pulp confined only to the coronal portion of tooth.

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• Contraindications: – Pathologic root resorption or radiolucency seen on radiograph – Profuse bleeding that persists for long after coronal pulp amputation – In a tooth that is about to exfoliate – In a tooth with draining abscess. • Objectives: – Radicular pulp asymptomatic with no adverse signs or symptoms such as sensitivity, pain or swelling – No postoperative radiographic evidence of pathologic external root resorption – Self-limiting and stable internal root resorption which should be monitored. – No harm to succedaneous tooth. • Materials used: Calcium hydroxide has been used but has less long-term success. – Formocresol – Ferric sulfate – Glutaraldehyde – MTA, more recent material used for pulpotomy has high success rate and is now preferred pulpotomy agent. – Electrosurgery used for pulpotomy also has shown good results. • Pulpotomy agents used and technique for pulpotomy: 1. Formocresol pulpotomy - One-fifth concentration formocresol can be used for pulpotomy which is prepared as follows: ■ 3 parts of glycerin + 1 part of distilled water (to prepare diluent) ■ One part formocresol + 4 parts of diluent - Formocresol causes tissue fixation. - Technique: Figures 28.18A to G show the steps of formocresol pulpotomy ■ Anesthesia and rubber dam isolation. ■ Removal of caries. Figure 28.18A shows mandibular first primary molar with deep caries involving the pulp. Figure 28.18B shows excavation of caries using a round bur. ■ Removal of entire roof of pulp chamber with a high speed bur with adequate water coolant (Fig. 28.18C). ■ Removal of entire coronal pulp with a long shank round bur or spoon excavator to the level of orifices. (Fig. 28.18D) ■ Control of hemorrhage with moist cotton pellet pressure placed over the opening of the root canals. ■ Then a cotton pellet dipped in the diluted formocresol is placed in direct contact with

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A

C

B

D

Figs 28.18A to D  Steps of pulpotomy in primary teeth. (A) Caries involving coronal pulp in a mandibular first primary molar; (B) Excavation of caries using a round bur; (C) Removal of the roof of the pulp chamber; (D) Amputation of coronal pulp to the level of orifices using a spoon excavator

the pulp stumps. This cotton is left in contact with the pulp stumps for 5 minutes (Fig. 28.18E). ■ A base of ZOE may be placed over stumps ■ The tooth is restored permanently (Fig. 28.18F). Restoration can be composite resin in anterior teeth and glass ionomer or amalgam or composite restoration followed by stainless steel crown for primary molars (Fig. 28.18G). - Safety: There are concerns about the systemic distribution of formocresol and its likely

carcinogenic potential and regarding its safe use in dentistry. 2. Glutaraldehyde pulpotomy: 2–4% aqueous glutaraldehyde can be used for pulpotomy instead of formocresol. - Advantages of glutaraldehyde over formocresol: ■ Less cytotoxic than formocresol ■ It has less systemic distribution after appli­ cation and does not diffuse out of the apex of the tooth. There is limited tissue binding and remainder of glutaraldehyde gets excreted in urine or exhaled as carbon dioxide.

Pediatric Endodontics

E

F



■ With glutaraldehyde, there is rapid fixation of the underlying pulpal tissue and the remaining radicular pulp maintains vitality and is free of inflammation. – Technique: Similar to formocresol pulpotomy – Disadvantages: - Not as successful as formocresol pulpotomy - Limited shelf life.

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G

Figs 28.18E to G  Steps of pulpotomy in primary teeth. (E) Cotton pellet dipped in formocresol is placed over pulp stumps for 5 minutes; (F) A base of zinc oxide eugenol is given and covered with a permanent restoration such as glass ionomer or silver amalgam; (G) The tooth is protected with stainless steel crown

3. Ferric sulfate pulpotomy: Ferric sulfate can also be used to replace formocresol for pulpotomy and has been shown to give reasonably good clinical and radiographic results. 4. MTA pulpotomy: Formocresol can be replaced with mineral trioxide aggregate for pulpotomy in primary teeth with good results.

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A

B

C

D

E (i)

E (ii)

Figs 28.19A to E  Steps of pulpotomy. (A) Mandibular second primary molar is isolated using rubber dam after adequate anesthesia; (B) Caries is excavated completely; (C) Deroofing the pulp chamber; (D) Coronal pulp is removed and hemostasis is achieved; (E) Pulpotomy agent is placed and the tooth is restored with a temporary cement: (i) Photograph showing good temporary seal achieved after pulpotomy: (ii) Postoperative radiograph of the same case in which pulpotomy was performed for mandibular second primary molar and pulpectomy was performed for mandibular first primary molar (Courtesy of Dr Ashwin Jawdekar)

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But, the disadvantages include high cost of the material and it may cause pulp canal obliteration.

Summary of Pulpotomy Procedure • Case selection • Asepsis • Hemostasis • Coronal seal Figures 28.19A to E are the case photographs demon­ strating the technique of pulpotomy in mandibular second primary molar.

Nonvital Pulp Therapy for Primary Teeth Pulpectomy It involves extirpation of pulp from both coronal and radicular spaces, cleaning and shaping of canals and obturation with a resorbable root filling material. • Indications: – Irreversible pulpitis – Necrotic pulp • Contraindications: – Tooth close to exfoliation having moderate to excessive mobility – Nonrestorable tooth with only carious root piece or stump remaining. In such cases, extraction of primary tooth followed by space maintainer would be preferred. • Objectives: – Following pulpectomy treatment, radiographic radiolucency suggestive of infectious process should resolve in six months. – Pretreatment clinical signs and symptoms should resolve in few weeks. – Optimum root canal filling evidenced on radiograph with no gross overextension or underfilling – Treatment should permit physiologic resorption of primary tooth and filling material to allow for normal eruption of succedaneous tooth – No pathologic resorption or furcation/apical radiolucency • Technique: Figures 28.20A to F show the steps of pulpectomy in a primary molar tooth: – Anesthesia and rubber dam isolation. – Removal of caries. Figure 28.20A shows deep caries in mandibular primary molar involving the pulp. Figure 28.20B shows excavation of caries and access cavity preparation.

A

B Figs 28.20A and B  Steps of pulpectomy in primary teeth. (A) Mandi­ bular first primary molar with extensive caries involving the pulp; (B) Excavation of caries and access cavity preparation

– Access cavity preparation is done by connecting all the pulp horns. Access preparation is made through the lingual surface for the anterior primary teeth and through the occlusal surface for the primary molar teeth. – Removal of roof of pulp chamber followed by entire coronal pulp to the level of orifices.

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C

D

Figs 28.20C and D  (C) Extirpation of pulp and cleaning and shaping of root canals: Circumferential filing with K-files in sequence to a predetermined length estimated from a preoperative radiograph; (D) After thorough debridement, the canals are filled with zinc oxide eugenol (Obturation)

– Flaring of access preparation walls for easy insertion of files and to achieve straight line access to the apical portion of the canals. – From preoperative radiograph, determine the approximate length of roots and then measure the Endodontic instruments such as K-files about 1 mm short of the apex. – Barbed broach or the smaller files can be inserted in the canals to this length for pulp extirpation (Fig. 28.20C). – Copious irrigation with sodium hypochlorite 3% or sterile saline should be done. – Cleaning and shaping: Circumferential filing with 2–3 K-files or H-files in sequence of size to the length, should be done. Excessive enlargement of canals may cause unnecessary damage to tooth such as perforation and hence should be avoided. Stainless steel or nickel-titanium (Ni-Ti) instruments can be used. Ni-Ti instruments are recommended due to their flexibility. Both hand and rotary instruments can be used. If stainless steel instruments are used, the instruments need to be gently curved to help negotiate the canals.   The objective of cleaning and shaping in primary teeth is to remove the pulp tissue and debris from the canals and make space for a resorbable root filling material.

– Irrigation of canals and then dry the canals with sterile paper points. – Then, obturation of canals with a suitable obturation material (Fig. 28.20D). • Ideal requirements of obturation material for primary teeth: – Biocompatible – Antiseptic – Resorbable—at par with tooth – Good handling – Economical – Radiopaque • Materials used for obturation of root canals of primary teeth (Table 28.1): – Zinc oxide eugenol: Zinc oxide eugenol is biocompatible, antiseptic and has good handling properties. It is economical and is a time-tested material. It has been used as an obturation material for primary teeth since many years. The limitation of ZOE is that it resorbs very slowly. Its resorption is not par with resorption of roots of primary teeth. – C a l c i u m h y d r o x i d e : C a l c i u m h y d r o x i d e is biocompatible and has excellent antiseptic properties. But its antiseptic action is short-lived. Within few days, its pH becomes neutral and becomes ineffective. It rapidly resorbs from the root canal. Although, it is a good material to be used for

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TABLE 28.1  Materials used in pulpectomy of primary teeth Requirements

ZOE

Ca(OH)2

Vitapex

Endoflas

Biocompatible

Y

Y

Y

Y

Antiseptic

Y/N

Y/N

Y

Y

Resorbable—at par with tooth

Y/N

N

Y/N

Y/N

Good handling

Y

Y/N

Y

Y

Economical

Y

Y

N

Y/N

TABLE 28.2  Selection of obturation material for primary teeth Pulp status

E

F Figs 28.20E and F  (E) After obturation with zinc oxide eugenol, permanent restoration such as glass ionomer or silver amalgam is placed in the pulp chamber space; (F) The tooth is protected with a full coverage restoration-stainless steel crown

intracanal dressing (medicament), its not suitable to be used as obturation material for primary teeth. To resist its rapid resorption and to make use of its antiseptic properties, it has been combined with other medicaments such as iodoform. – Calcium hydroxide and iodoform mixture—nonsetting, commercially available as Vitapex, is a very

Teeth Incisors

Canines and molars

Abscessed/nonvital

Ca(OH)2 + Iodoform (Nonsetting)

Ca(OH)2 +Iodoform (hard setting) or ZOE after 1 week interappointment dressing using Ca(OH)2

Nonabscessed/vital

Ca(OH)2 + Iodoform (Nonsetting)

ZOE or Ca(OH)2 + Iodoform (nonsetting or hard setting)

good primary root canal filling material and has following desirable properties: - Easy to apply - Resorbs slightly faster than roots of primary teeth - Has no toxic effects on permanent successor - It is radiopaque. This combination is being widely used now-adays for obturation of primary teeth. It is available as preloaded syringes with thin intracanal tips, which makes its delivery in the canal very easy. • Calcium hydroxide and iodoform mixture-hard setting, commercially available as Endoflas, is also a good material for obturation of primary teeth. It undergoes faster resorption as compared to ZOE and is hardsetting. It is also available as preloaded syringes for easy delivery in the root canals. Clinical implications: (Table 28.2 Selection of obturation material for primary teeth ) • In case of primary incisors, it is always preferred to use a nonsetting calcium hydroxide and iodoform combination so that their roots resorb in time and there is no delay in its shedding. Over-retained primary incisors can deflect the path of eruption of permanent incisors and can cause cross-bite.

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• In case of primary canines and molars with necrotic pulp and abscess, if nonsetting obturation material is used, there is high possibility that it will get resorbed easily. So, a hardsetting material is preferred such as calcium hydroxide with iodoform-hard setting (Endoflas). Alternatively, in such cases, calcium hydroxide dressing can be given for one week and then ZOE can be used as obturation material when the canals are dry. • In case of primary canines and molars which had a vital pulp, any of the obturation material: ZOE, calcium hydroxide and iodoform combination—nonsetting or hard-setting, can be used. • Obturation techniques in primary teeth: – Incremental: The canals can be coated with the paste of unreinforced ZOE using paper points, k-files or spreader incrementally.

A

– Pressure syringe: Commercially available filling devices are available such as Navitip, Vitapex syringe, etc – Syringe with needle – Wet cotton: The pulp chamber is filled with the obturating material such as ZOE and a wet cotton pellet is pressed over it few times so that it flows into the canals. – Lentulospiral: Endodontic hard instruments such as files or rotary lentulospiral fillers can be used. Important thing to note in case of filling using lentulospiral fillers is that it should be inserted and removed from the canal while in rotation. The rotation should not be started or stopped when in the canal for its effective use otherwise the ZOE gets removed with the lentulospiral filler.

B Figs 28.21A and B  Stainless steel crowns placed on Endodontically treated deciduous and permanent molars (Courtesy of Dr Ashwin Jawdekar)

A

B

C

Figs 28.22A to C  Radiographs of a pulpally involved primary molar in which pulpectomy was performed. (A) Preoperative radiograph; (B) Intraoperative radiograph with K-files inserted in the canals for determination of working length; (C) Postoperative radiograph

Pediatric Endodontics

-

Radiograph can then be taken to confirm if the canals have been adequately filled. - After obturation with zinc oxide eugenol, permanent restoration such as glass ionomer or silver amalgam is placed in the pulp chamber space (Fig. 28.20E) - Tooth should be restored with stainless steel crown (Figs 28.20F and 28.21A and B) - In case if the succedaneous permanent tooth is missing and the retained primary tooth is pulpally involved, the canals can be filled with gutta-percha after pulpectomy.

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Figures 28.22A to C show the radiographs of primary mandibular second molar tooth (Pre-intra- and postoperative views).

BIBLIOGRAPHY 1. Cohen S, Hargreaves KM. Pathways of Pulp, 9th edn. St. Louis: Mosby, 2006.pp.822-74. 2. Dr Ashwin Jawdekar, Little Smiles Child Care Pvt. Ltd., Presentations and Notes. 3. Ingle J, Bakland L, Baumgartner J. Ingle’s Endodontics, 6th edn. BC Decker Inc, Hamilton, 2008.pp.1400-25. 4. Reference Manual, V 36/No 6, 14/15, AAPD. Guideline on Pulp Therapy for Primary and Immature Permanent Teeth.

CHAPTER

29

Geriatric Endodontics

This chapter describes the Endodontic treatment for the geriatric patients and explains the specific features of the older patients that may require special considerations.   You must know • What is Geriatric Endodontics? • What is the Scope of Geriatric Endodontics? • What is the Need for Geriatric Endodontics? • What are the Specific Features of General Health of Older Patients? • What are the Regressive Changes that occur in the Teeth with Increasing Age? • What are the Specific Features of Teeth of Older Patients? • Which Orofacial and Dental Signs and Symptoms are Elicited by Clinician to Derive Correct Diagnosis? • What are the Different Diagnostic Tests? • How to Formulate Treatment Plan after making Correct Diagnosis in Geriatric Patient? • What are the Steps in Endodontic Treatment in Geriatric Patient?

WHAT IS GERIATRIC ENDODONTICS? Dental clinics of North America (1989) defined Geriatric Dentistry as the provision of dental care for adult persons with one or more chronic debilitating, physical or mental illness with associated medication and psychosocial problems. Endodontic treatment for the older adults, such as for patients over the age of 65 years, is called geriatric Endodontics. Geriatric dentistry is emerging as a specialized branch of dentistry and The National Institute of Aging has stated that all dental professionals should receive education and training for the management of elderly patients, as a part of basic professional education.

WHAT IS THE SCOPE OF GERIATRIC ENDODONTICS? Geriatric Endodontics deals with following as given in Figure 29.1.

WHAT IS THE NEED FOR GERIATRIC ENDODONTICS? Need for Geriatric Endodontics • With the improvement in standard of living and availability of advanced medical care, the percentage of aged persons in the society has increased. • Quality of life of older patients can be significantly improved by saving teeth through Endodontic treatment.

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• Decline in renal and liver function that may alter the behavior and interaction of drugs in the body. • Certain complex conditions and medical problems might make a patient functionally dependent. • Symptoms of certain undiagnosed illness may be present. • Visual and auditory deficits can make communication difficult.

WHAT ARE THE REGRESSIVE CHANGES THAT OCCUR IN THE TEETH WITH INCREASING AGE? Regressive Changes in the Teeth

Fig. 29.1  Scope of geriatric Endodontics



This can have a great value in improving the overall dental, physical and mental health. • Root canal treatment, if possible, is definitely a favorable alternative to the trauma of extraction and the subsequent cost of replacement. • Since, the primary function of teeth is mastication, loss of teeth can lead to detrimental changes in food intake habits resulting in reduction in general health of the patient. • For some patients, social issues can be a reason to save natural anterior teeth. Endodontic treatment is certainly less traumatic in the extremes of age or health, than is extraction. Due to increased awareness of benefits of saving teeth, many older patients now seek Endodontia rather than extraction.

WHAT ARE THE SPECIFIC FEATURES OF GENERAL HEALTH OF OLDER PATIENTS? • With increasing age, the biological functions of body are compromised. There may be reduced blood supply, brittle bones and weak host resistance. • Age-related changes in cardiovascular system, respiratory system and central nervous system may result in drug therapy needs.

• Enamel: – Decrease in the permeability of enamel – Wasting diseases causing loss of enamel (attrition, abrasion and erosion) – Enamel becomes slightly brittle with age. • Dentin: – Decrease in permeability of dentin – Secondary and reparative dentin deposition – Deposition of peritubular dentin and gradual obliteration of dentinal tubules – Dentin sclerosis • Pulp: – More fibers, less cells – Reduced pulp volume – Small geriatric canals – Decreased blood supply to tooth – Calcification in pulp chamber and root canals. – Calcification process associated with aging appears clinically to be more of linear type than that which occurs in younger tooth in response to caries or trauma. – Constant deposition of cementum throughout life increases the length of the canal from actual anatomic foramen to cementodentinal junction • Root: – Conditions like hypercementosis – Apical root resorption may be present. Figures 29.2A and B show comparison between root canal system of young permanent tooth with that of a geriatric tooth.

WHAT ARE THE SPECIFIC FEATURES OF TEETH OF OLDER PATIENTS? Specific features of teeth in elderly are described in Table 29.1.

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WHICH OROFACIAL AND DENTAL SIGNS AND SYMPTOMS ARE ELICITED BY CLINICIAN TO DERIVE CORRECT DIAGNOSIS? Subjective symptoms

A

B

Figs 29.2A and B  Diagram showing comparison between an adult tooth root canal system with that of a geriatric patient: (A) Root canal system in a young adult tooth; (B) Root canal system in a geriatric patient. a—Pulp horns: High pulp horns go on receding with increasing age, b—Pulp chamber: Large and wide pulp chambers become smaller and shorter, c—Root canals become thin, d— Cementum deposition causes thin narrow apical foramen, e—Pulp stone

TABLE 29.1  Specific features of teeth in elderly Clinical features

Related to symptoms

Related to healing and repair

• Radicular caries (Root decay) • Gingival recession • Periodontal problems • Poor oral hygiene • Wasting diseases of teeth: – Attrition – Abrasion, etc. • Sinus tracts • Missing teeth and tilted teeth can cause compensating bite which may result into temporomandibular joint (TMJ) dysfunction or loss of vertical dimension • Cracks or craze lines on teeth may be present • Interproximal root caries • Figures 29.3 and 29.4 show the intraoral clinical features in a geriatric patient

• Pain associated with vital pulps (i.e. Referred pain, pain caused by heat, cold, sweets) seems to be reduced with age • Severity seems to diminish over time • Heat sensitivity may occur as the only symptom due to reduced pulp volume • Necrosis may occur quickly after microbial invasion, again with reduced symptoms • High conduction nerve endings in dentin are reduced or absent, and dentinal tubules are calcified; so patient may not feel pain until actual pulp exposure has occurred

• Pulp healing is reduced • Age-related changes in connective tissue and bone resulting in delayed repair of periapical tissues

Objective signs

• Clinician can ask specific • Clinician should do the following questions and allow examination and elicit specific signs: patient to express his A. Thorough extraoral examination: Check symptoms: for any facial asymmetry or distension A. Patient’s chief complaint. indicating swelling B. About pain: B.  Thorough intraoral examination: – Nature of pain – Examination of area of chief – Severity complaint. – Relationship to – Rule out predisposing factors to oral stimulus or irritant cancers which may initially manifest – Aggravating and as prodromal signs or symptoms relieving factors – Decreased salivation (xerostomia) Any specific symptom due to certain medications resulting that patient would like to in dental caries and oral fungal speak about infections – Gingival recession causing hypersensitivity of exposed dentin and cementum. – Periodontal examination. – Failed restorations, marginal leakage – If sinus tract is present, gutta-percha can be used to trace its origin

WHAT ARE THE DIFFERENT DIAGNOSTIC TESTS? • Inspection • Slow and gentle percussion and palpation • Transillumination and staining to detect cracks in case of presence of symptoms • Pulp testing: It detects the response of pulp to stimuli and irritants. The response to stimuli may be weaker than young pulps due to fewer nerve branches and mineralization in older pulps.

Geriatric Endodontics

Fig. 29.3  Geriatric patient showing abrasion and erosion

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• Radiographs: In geriatric patients: – It may be difficult to place the film, especially if tori are present or if patient is unable to hold the film. Film holders can be helpful. – Exposure time will have to be increased to get proper diagnostic contrast if exostoses and dense bone is present. – Early bone changes can be detected effectively by digital radiography as compared to conventional radiography. – Evaluate the radiograph for the following: - Receding pulp horns - Depth of pulp chamber - Presence of pulp stones - Proximal and root caries and restorations - Calcification between observable pulp chamber and root canal in case of deep restorations - Number of roots - Root canals — number, size, shape and curvature - Midroot disappearance of a detectable canal may indicate bifurcation.

HOW TO FORMULATE TREATMENT PLAN AFTER MAKING CORRECT DIAGNOSIS IN GERIATRIC PATIENT? Based on patient’s history, clinical examination and interpretation of various diagnostic tests, determine: • Vitality of tooth: Vital/nonvital • Presence or absence of periapical pathologic conditions and determine whether root canal treatment is indicated.

Fig. 29.4  Geriatric patient showing attrition, abrasion, gingival recession and craze lines

In elderly patients, it becomes difficult to perform and interpret results of electric and thermal pulp testing due to – Extensive restorations – Pulp recession – Excessive calcifications • Test Cavity: – Less useful due to reduced dentin innervation – Should be used only when other tests have failed to give correct diagnosis.

Once you plan to do RCT, then: • Consultation with patient’s relatives, obtain informed consent from patient and obtain valid consent from patient’s physician in case of any medical problem • Then schedule the appointment as per patient’s convenience • Decide whether single-visit or multiple visit approach would be suitable • Consider patient’s comfort, chair position, jaw fatigue and choice of anesthetic.

WHAT ARE THE STEPS IN ENDODONTIC TREATMENT IN GERIATRIC PATIENT? • Pretreatment • Access cavity preparation • Cleaning and shaping/biomechanical preparation

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• Obturation • Post-Endodontic restoration • Repair after endodontic treatment

Pretreatment • Administration of appropriate local anesthetic (LA) • Isolation with rubber dam

Access Cavity Preparation • The most difficult step in Endodontic treatment of older patients is adequate access and identification of root canal orifices. This may be due to thin, small geriatric canals, which may be calcified most of the times that makes location and penetration of canal orifice quite difficult and time-consuming. • Remove caries and existing restorations if any, under suitable magnification in the form of loupes or microscopes. • Location and initial penetration of the canal orifice with DG-16 explorer. Canal negotiation with #8 k-file with gentle apical pressure and prelubricated with a chelating agent. • If risk of deviation from long axis exists such as in heavily restored tooth or calcified canals, surgical access may be preferred. • Errors: – Canals may be overlooked. Careful location of orifices is important. – Perforation: Pain, bleeding, disorientation of probing instrument may indicate perforation.

Cleaning and Shaping (Biomechanical Preparation) • Reparative dentin deposition and calcification makes penetration of canals difficult • Due to constant deposition of cementum throughout life, length of canal from actual anatomic foramen to CDJ increases, but actual CDJ width remains constant with age. • Usually crown-down technique is followed: Flaring of coronal 1/3rd of canal to provide a reservoir of irrigating solution and reduce the stress on metal instruments. • Thorough copious irrigation with sodium hypochlorite to remove debris that block access. • Instruments with no rake angle are beneficial. • Canal preparation should terminate at CDJ (narrowest constriction of canal): 0.5 to 2.5 mm from radiographic apex.

• Difficulties encountered in cleaning and shaping in root canals of geriatric patients: – Reduced tactile sense in identifying constriction due to calcification – In cases with hypercementosis, there is difficulty in penetration of the canal in the apical third – Achieving and maintaining patency are difficult – Reduced periapical sensitivity causes reduced response of patient that otherwise indicates penetration of apical foramen.

Obturation of Root Canal System • For older patients, excessive pressure during obturation can result in root fracture. So, the obturation techniques that do not require unusually large mid-root tapers and do not generate pressure in this area are selected. • Obturation using a thermoplasticized material such as resilon, can significantly reduce coronal leakage that can result from root caries after Endodontic treatment and also it increases resistance to root fracture. • Permanent restorative procedures should be scheduled as soon as possible to prevent coronal leakage.

Post-Endodontic Restoration • Root fracture is common in older adults when posts with much taper is used. • Post fracture or failure may occur when small diameter parallel post is used. • In older patients, factors determining type of restoration include root caries, cervical erosion, gingival recession, bone loss and lesser number of teeth remaining. • In case of older patients, often multiple teeth are missing. So there may be insufficient vertical and horizontal space when opposing or adjacent teeth are missing.

Repair after Endodontic Treatment • Repair may be delayed due to age-related changes such as: – Increase in atherosclerotic changes of blood vessels – Viscosity of connective tissue is altered – Decrease in rate of bone formation and normal resorption – Greater porosity of bone – Decreased mineralization of formed bone • In case of vital pulps with normal periapical tissue: Good prognosis of Endodontic therapy and periapical tissue can be maintained normal by confining preparation and filling procedures to canal space.

Geriatric Endodontics

• In case of infected nonvital pulps with periapical pathologic abnormalities: Repair is determined by ability of host tissue to respond.

Endodontic Surgery in Geriatric Patients Endodontic surgery may be considered in geriatric patients if the case is definitive indication for surgery, but may require medical consultation.

Considerations for Endodontic Surgery Medical

Local

Thorough evaluation of Medical history is done. Some special considerations may be needed: • Prophylactic antibiotic premedication • Sedation • Hospitalization • More detailed evaluation

• Presence of fenestrated or dehisced roots and exostoses • Thickness of overlying soft and bony tissue. • Relationship of anatomic structures such as sinus, floor of nose, neurovascular bundle with surrounding structures may change when teeth are lost. • If root end surgery is to be performed, consider whether the root that will be left is long enough and thick enough for tooth to remain functional and stable after surgery.

Need for Endodontic Surgery Surgical access may be preferred in case of anatomic complications of RC system such as small or completely calcified canal, non-negotiable root curvatures, extensive apical root resorption or pulp stones. Perforation during access, losing length during instru­m entation, ledging and instrument separation are iatrogenic treatment complications associated with treatment of calcified canals. Hence, surgical Endodontics may be considered.

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BIBLIOGRAPHY 1. Cohen S, Hargreaves KM. Pathways of Pulp, 9th edn. St. Louis: Mosby, 2006.pp.883-915.

CHAPTER

30

Pathologic Tooth Resorption

This chapter explains in detail about tooth resorption and its different types.   You must know • What is Tooth Resorption? • What is Mechanism of Tooth Resorption? • What are the Etiologic and Stimulating Factors of Tooth Resorption? • Which are the Types of Tooth Resorption? • Which are the Clinical and Radiographic Features of Different Types of Tooth Resorption and How to Manage them? • What are the Differences between External and Internal Root Resorption?

WHAT IS TOOTH RESORPTION? According to American Association of Endodontists (1984). Resorption is defined as, “A condition associated with either a physiologic or a pathologic process that results in loss of substance from a tissue such as dentin, cementum or alveolar bone.” Bone undergoes apposition and resorption as a part of continual remodelling process. In case of teeth: • Roots of primary teeth undergo resorption during exfoliation. This resorption is considered physiologic. Sometimes, pathologic resorption may occur. • Roots of permanent teeth do not undergo resorption normally. Intact cementoblast and odontoblast cell layers that are present in the tooth normally, provide immunity to permanent teeth against resorption (Homeostasis Phenomenon of Pulp and Periodontal Ligament) Physical and chemical insults to these layers causes loss of protection and can lead to Resorption. This resorption of roots of permanent teeth is considered pathologic. If the permanent tooth germ lies in an ectopic position, then the process of physiologic resorption of

primary predecessor can cause nonphysiologic root resorption of adjacent permanent tooth.

WHAT IS MECHANISM OF TOOTH RESORPTION? Cells involved in tooth resorption: • Osteoclast: Osteoclast are giant cells that play an important role in the following: – Tooth eruption: - Osteoclast plays a role in physiologic resorption of primary teeth - During development of permanent successor and the eruption process, coronal part of the follicle induces a rim of osteoclast, which is involved in the resorption of roots of primary predecessor and adjacent bone. - Chronic periapical inflammation from pulp necrosis in primary teeth accelerates its shedding. – Alveolar bone growth and maintenance: - Continuous bone remodelling (osteoblastic and osteoclastic activity) occurs throughout life. Lack of equilibrium in activity of these two cells causes osteoporosis or osteosclerosis. - In case of replacement resorption (ankylosis), tooth becomes a part of general bone remodelling

Pathologic Tooth Resorption

system and continuous replacement of root with bone takes place. – Repair after injury: - Osteoclast has a role in revascularization process in bone and teeth. - This occurs in case of luxation injuries and root fracture with displacement of teeth. - This is termed as transient apical breakdown, transient marginal breakdown, transient ankylosis or transient internal surface resorption depending on location of the process. – Defense cell against microbial invasion: - Microbial invasion occurs in cervical area of tooth due to plaque accumulation and periodontal pocket formation and in apical area of tooth due to bacterial accumulation in the root canal. - In both the cases, bacteria and inflammatory cells release a series of osteoclast-promoting signals that stimulate osteoclast generation and accelerate osteoclast activities. Methods to control osteoclastic activity: Certain medicaments have been tried to inactivate the osteoclast activators, which are the triggers of root resorption. Ledermix (Tetracycline+Triamcinolone) topically applied in the root canal can reduce the extent of osteoclastic attack on the root. Another alternative way is to change the dentin environment from a neutral pH to a basic pH, that may interfere with the Osteoclast’s mineral dissolution. • Odontoclasts and cementoclasts: These are the resorptive cells that are involved in the tooth resorption. • Monocytes and macrophages: They are inflammatory cells which are phagocytic in function.

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Mechanism of Root Resorption After an osteoclast is formed, it resorbs hard tissues such as cementum, dentin, enamel or bone. Mechanism of hard tissue destruction by osteoclasts involves: • Dissolution of inorganic material (hydroxyapatite) by acids by the action of polarized proton pump produced by ruffled border of the clast cells and enzyme carbonic anhydrase II and acid phosphatase. • Breakdown of organic matrix containing type I collagen by enzymes such as collagenase and cysteine proteinase.

WHAT ARE THE ETIOLOGIC AND STIMULATING FACTORS OF TOOTH RESORPTION? Tooth resorption may occur due to the following causes or situations such as: • Pulpal infection • Periapical infection • Periodontal infection • Reimplantation cases • Excessive mechanical or occlusal forces during orthodontic treatment • Pressure caused by impacted tooth • Pressure caused by tumors and cysts • Idiopathic.

WHICH ARE THE TYPES OF TOOTH RESORPTION? Classification of root resorption: • According to etiology:

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• According to Andreasen and Bakland (Ingle’s Endodontics):

• According to Levin and Trope:

WHICH ARE THE CLINICAL AND RADIOGRAPHIC FEATURES OF DIFFERENT TYPES OF TOOTH RESORPTION AND HOW TO MANAGE THEM? External Root Resorption Definition: “External resorption is a lytic process occurring in cementum or cementum and dentin of the roots of the teeth.” (Grossman’s Endodontic Practice, 11th edn, Pg. 98). It is resorption that occurs on the external or lateral surface of the root. Injury may be only to the external root surface with no inflammation in root canal. But, sometimes injury to external root surface is associated with an inflammatory stimulus in root canal. In such cases, there are chances of pulp necrosis causing pulp space infection.

Types of External Root Resorption 1. External surface resorption (repair-related resorption): It represents the healing response to chronic and/or acute injury in the PDL that affects the cells adjacent to the root surface.

Fig. 30.1  External root resorption

Figure 30.1 shows diagrammatic representation of External root resorption. • Etiology and pathogenesis: – Acute repair-related resorption may occur in case of: - Dental traumatic injuries: Luxation injuries (Concussion, subluxation and lateral luxation) and following Intrusion - Replantation of avulsed teeth. - Root fracture: Here it may be found adjacent to the fracture line. – Chronic injury: Associated with orthodontic treatment, traumatic occlusion, pressure from cysts or tumors and ectopically erupted teeth. When the trauma and/or pressure is discontinued, spontaneous healing tends to occur. This is a typical feature of repair-related resorption. The injured tissue is removed by osteoclast and macrophages in about 2–4 weeks, following which repair occurs by progenitor cells from adjacent PDL. • Clinical features: No significant signs or symptoms.

Pathologic Tooth Resorption

• Types: – Transient surface resorption: In this resorption, tooth has vital healthy pulp that has recovered from traumatic event. New cementum is deposited and resorbed area is restored to normal surface contour. – Progressive surface resorption: It progresses to a more destructive resorption, either inflammatory resorption or replacement resorption. • Radiographic features: Repair-related resorption have very limited size. So, they may not be recognized radiographically. After about 2–4 weeks, localized widening of the PDL space occurs. Slight cavitations may be seen on the lateral root surface or at the apex. As a result, roots appear shorter in size. • Treatment: It is a self-limiting process and does not require any treatment. On elimination of trauma and/ or pressure, 100% repair usually occurs. 2. External infection-related resorption (inflammatory root resorption): It represents a combined injury to the pulp and the PDL, where bacteria located in dentinal tubules and pulp space trigger osteoclastic activity on the root surface. • Etiology and pathogenesis: Exclusively related to acute trauma, commonly seen after intrusion or replantation of avulsed teeth. Bacterial toxins present in dentinal tubules and/ or infected root canal can be diffused to the PDL via the exposed dentinal tubules, which continues the osteoclastic process and associated inflammation in the PDL, leading to resorption of adjacent alveolar bone. Resorption process involves the root dentin and the root canal gets exposed. If bacteria are eliminated from the dentinal tubules and the root canal by Endodontic therapy, resorption process will arrest. • Types: – Cervical: External inflammatory root resorption that occurs on the area of root surface just below the attachment apparatus. – Apical: External inflammatory root resorption that is confined to the apex because of sufficient pressure to overcome the resistance of the cemental layer to resorption. • Clinical features: This type of resorption is rapidly progressing and may result in total resorption of roots in few months. Patient usually gives history of trauma. There is increased mobility in the involved tooth and has dull percussion tone. The tooth may be extruded. Inflammation of periodontal tissues is seen. • Radiographic features: After 2–4 weeks of injury, it appears as progressive cavitations involving the root

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and adjacent alveolar bone. A bowl like radiolucency is seen with ragged irregular areas on the root surface. • Treatment : Immediate Endodontic treatment to control or remove osteoclast-promoting factors. In case of mature teeth, prophylactic extirpation of pulp in replanted avulsed teeth. Use of sodium hypochlorite and calcium hydroxide is recommended during cleaning and shaping. Obturation of the root canal is done after 2–3 weeks. In case of immature teeth, apexification procedure needs to be performed. 3. External trauma-related replacement resorption (ankylosis): It represents a sequel to injury in PDL including cell layer next to cementum. • Etiology: Acute trauma. For example: Severe luxations such as lateral luxations, intrusion or replantation of avulsed teeth. In moderate sized injuries, an initial transient ankylosis develops. (Later areas of resorption get replaced with new cementum and PDL). In extensive injuries, progressive ankylosis occurs (tooth becomes a part of bone remodelling system) • Clinical features: A tooth with ankylosis-related root resorption appears firm in its socket, with high metallic sound on percussion. Infraocclusion, incomplete alveolar process development in case of young patient. • Radiographic features: Moth-eaten appearance with irregular border, absence of periodontal ligament and lamina dura. • Treatment: – Decoronation treatment: In children and adolescents, removal of crown of the tooth and leave behind root portion allowing continued vertical growth of alveolus. – Breaking of ankylosis sites (luxation of tooth) 4. External spontaneous ankylotic resorption • Etiology and pathogenesis: Not known. But may be related to the instability of the RANK-RANKL-OPG system. The ankylosis-related resorption causes infraposition of involved tooth in young individuals and gradual substitution of root by bone. • Clinical features: In primary dentition, mandibular second primary molar is commonly involved tooth. Ankylosis causes infraposition of tooth and tilting of neighboring teeth. In permanent dentition, first and second permanent molars are commonly involved teeth. Ankylosis causes gradual infraposition of tooth and high and metallic percussion tone. • Radiographic features: Ankylosis begins in interdental area and then gradually spreads to remaining part of the root in case of primary molars. In case of permanent

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molars, replacement resorption starts in intraradicular area and gradually spread to remaining part of the root. • Treatment: Endodontic treatment should not be done as it aggravates the aggressive nature of ankylosis process. In case of primary dentition, decoronation treatment in early stages. If it is diagnosed late (during adolescence) then it should be rebuild to prevent supraeruption of antagonistic tooth. In permanent dentition, if diagnosed early, extraction of involved tooth. If diagnosed later, then rebuild the tooth to prevent supraeruption of the antagonist tooth.

Internal Root Resorption “Internal resorption is an idiopathic slow or fast progressive resorptive process occurring in the dentin of the pulp chamber or root canals of teeth”. • It represents progressive pulp healing. • It begins centrally within the tooth, initiated by inflammation of the pulp. • It is less common than external root resorption in permanent teeth • An oval-shaped enlargement of root canal space is seen in internal root resorption. • The multinucleated giant cells adjacent to granulation tissue in the pulp cause the resorption of internal aspect of the root. Figure 30.2 shows diagrammatic representation of internal root resorption. • Etiology: Not exactly known (Idiopathic) – Trauma has been found to be an initiating factor. – Iatrogenic: Extreme heat produced during cutting dentin without an adequate water coolant, partial removal of pulp, pulp capping or pulpotomy using calcium hydroxide. – Caries.

• Coronal portion of tooth may be necrotic. • Pulp in the apical portion that includes the internal resorptive defect may be vital. • After a period of active resorption, tooth may become nonvital. • Diagnosis – ‘Pink spot’ appearance of crown in later stages of resorption when integrity of crown is compromised. – Later stages may be associated with perforations. – On radiographic examination: - Round or ovoid uniform radiolucent enlargement of the pulp canal may be seen Figure 30.4 shows

Fig. 30.2  Internal root resorption

Clinical Features • Usually asymptomatic. Pain may be a symptom if perforation of crown occurs. Thus, two types of internal root resorption: 1. Nonperforating (asymptomatic) 2. Perforating (painful) • Maxillary anterior tooth is found to be commonly affected. • Reddish area showing through the resorbed area of the crown representing the granulation tissue is the pathognomonic sign of internal resorption (Figure 30.3 shows reddish-pink discoloration in maxillary right central incisor suggestive of internal resorption. Also referred to as “pink tooth”).

Fig. 30.3  Internal resorption in maxillary right central incisor (pink tooth) (Courtesy of Dr Manoj Ramugade)

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Fig. 30.4  Radiograph showing internal resorption in maxillary left central incisor tooth which has perforated the root (perforating internal resorption)

Fig. 30.5  CBCT scan image of a tooth with internal resorption. Note the oval-shaped enlargement of root canal space (Courtesy of Dr Mansi Shah, Dentoview-Advanced dental imaging center)

an intraoral periapical radiograph showing internal resorption (perforating type) in maxillary left central incisor tooth. Resorption begins in the root canal so some part of root canal space may show radiolucent resorptive defect. Distorted outline of root canal. At a very late stage, changes in the surrounding bone may be evident. CBCT is a recent diagnostic technique which gives 3-dimensional image unlike radiographs which are 2-dimensional. Any pathology present in the tooth buccolingually cannot be seen on radiographs but can be seen in CBCT images. Figure 30.5 shows CBCT image of a tooth with internal resorption which can be clearly appreciated in the center of the crown.

– Treatment: No treatment required. Only periodic observation. 2. Internal-infection related resorption/internal inflammatory resorption: It represents resorbing granulation tissue interposed between healthy and diseased pulp tissue. – Etiology and pathogenesis: Necrotic infected pulp tissue or pulp tissue with chronic inflammation is present coronal to resorption site in the pulp. Expansion of the resorption process eventually leads to fracture of the root. – Types: Internal inflammatory resorption is of two types:

- - - -

Types of Internal Root Resorption 1. Internal surface resorption: – Etiology and pathogenesis: Usually found in areas where revascularization occurs, such as: - Fracture lines of root fractures and in apical part of root canal and - Luxated tooth, apical part of root canal undergoing revascularization. It involves osteoclastic activity and formation of granulation tissue. – Radiographic features: Temporary widening of root canal is seen.

– Radiographic features: Round or ovoid radiolucency in the central portion of the tooth with smooth, well-defined margins. Lesion appears close to the root canal even if angulation of radiograph changes. – Treatment: Endodontic treatment to stop internal resorptive process by extirpation of pulp and delayed obturation after repair of defect with calcium hydroxide paste.

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3. Internal replacement resorption (metaplastic resorp­ tion): – Etiology and pathogenesis: Related to trauma mainly. Other causes include: extreme heat to tooth, pulpotomy procedures, etc. Damaged pulp tissue is replaced as a part of healing process with an in growth of new tissue which includes bone-derived cells. Root is gradually replaced by bone. The postnatal pulp stem cells which are present in the apical part of root canal are the source for the metaplastic hard tissue formed in replacement resorption as reparative response to restorative result. – Clinical features: Most of the times asymptomatic. If ankylosis occurs, tooth will gradually develop infraocclusion. – Radiographic features: Radiographically, it appears as a dissecting resorptive area in the center of root canal. Root canal space may appear engorged with radiopaque material suggestive of hard tissue. – Treatment: Endodontic treatment, although it may have poor prognosis due to lack of root maturity.



Cervical Invasive Resorption

WHAT ARE THE DIFFERENCES BETWEEN EXTERNAL AND INTERNAL ROOT RESORPTION?

It is a type of inflammatory root resorption occurring immediately below the epithelial attachment of tooth (which may be exactly at the apical margin or apical to the cervical margin). • Etiology and pathogenesis: The cause is related to a defect in the cementoblast layer (PDL defect) in its RANKRANKL-OPG system. May be related to: – Orthodontic treatment – Acute trauma – Cervical restoration – Bleaching of nonvital teeth – Periodontal treatment – Bruxism. The initial cervical resorption gradually spreads and may progress in apical and coronal direction eventually leading to fracture of the tooth. • Types: Heithersay has classified cervical root resorption into following four types: Class I: A small invasive resorptive defect near cervical area with shallow penetration into dentin. Class II: Well-defined resorptive defect close to coronal pulp chamber, with little or no involvement of radicular dentin. Class III: Deep resorptive defect involving coronal pulp and also coronal third of the root.

Class IV: Resorptive defect extending beyond the coronal third of the root. • Clinical features: Initially, the cervical invasive resorption is asymptomatic. Long-standing cervical resorption causes loss of tooth structure replaced by granulation tissue, which undermines the enamel. So, a “pink spot” next to the cervical margin is seen in expansive lesions. It should be differentiated from the pink tooth appearance of internal resorption, by radiographic examination. • Radiographic features: Appears as cervical bowl-shaped lesion that progresses in coronal and apical directions. In initial phases, the root canal is not involved. As the resorption progresses, the root canal gets involved. • Treatment: Raise a surgical flap, remove granulation tissue and place a dentin-bonded restoration. If pulp canal gets involved then Endodontic treatment. After Endodontic treatment, the resorbed area may be repaired from an internal or external approach. Intentional replantation and root amputation are the other treatment options in such cases. Figure 30.6 gives the mind-map to remember the different types of pathologic tooth resorption.

Distinguishing features of internal and external root resorption: External resorption

Internal resorption

This defect moves away from the canal as the angulation of radiograph changes

This defect appears close to the canal even if angulation of radiograph changes

Ragged or scooped out area on the side of the root

Here well-demarcated enlargement of the root canal. Walls of root canal appear to balloon out

Outline of root canal appears normal, defect is seen as “running through” radiolucent defect

Outline of root canal is distorted

Resorption of bone along with that of root. So, radiolucency in both root and bone is seen

Radiolucency is confined to root. Rarely bone may be involved if root perforation occurs

Variations in density of radiolucency

Uniform density of radiolucency

No pink spot

Pink spot (Pink tooth of mummery) is a possible sign; if present is pathognomic of internal root resorption

Its distribution is not symmetrical and can occur on any root surface

Its distribution over the root is symmetrical but may be eccentric

Pathologic Tooth Resorption

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Fig. 30.6  Mind-map to remember the different types of pathologic tooth resorption

BIBLIOGRAPHY 1. Cohen S, Hargreaves KM. Pathways of Pulp, 9th edn. St. Louis: Mosby, 2006.pp.630-9. 2. Ingle J, Bakland L, Baumgartner J. Ingle’s Endodontics, 6th edn. BC Decker Inc, Hamilton, 2008.pp.1358-80.

3. Zvi Fuss, Igor Tsesis, Shaul Lin. “Root Resorption-Diagnosis, Classification and Treatment Choices based on Stimulation Factors”, Dental Traumatology. Blackwell Munksgaard. 2003;19:175-82.

CHAPTER

31

Dentinal Hypersensitivity and its Management

This chapter explains in detail about dentinal hypersensitivity with respect to its etiology, diagnosis and different treatment modalities for its management.  You must know • What is Dentinal Hypersensitivity? • What are the Different Hypotheses put Forward to Explain the Mechanism of Dentinal Hypersensitivity? • What is the Incidence and Prevalence of Dentinal Hypersensitivity? • What are the Predisposing Factors that cause Dentinal Hypersensitivity? • How to Diagnose Dentinal Hypersensitivity? • How to Manage Dentinal Hypersensitivity?

WHAT IS DENTINAL HYPERSENSITIVITY? Dentinal Hypersensitivity is a sharp, quickly reversible pain in exposed dentin of a tooth that has no other form of dental pathosis, in response to thermal, evaporative, tactile, mechanical, osmotic or chemical stimuli. Dentin is normally covered by Enamel in crown and by cementum in the root. Loss of Enamel or Cementum due to various causes, which have been discussed later in this chapter, results in exposure of dentin to the oral environment. This exposed dentin may become more sensitive to external stimuli than the normal, immediately after exposure. But within a few weeks, sensitivity may diminish or subside due to gradual occlusion of dentinal tubules by mineral deposits with aging or chronic irritation. Reparative dentin deposition over the pulpal ends of exposed tubules also reduces sensitivity. However, some hypersensitive dentin may not spontaneously desensitize. Hypersensitive tooth: A tooth is termed ‘hypersensitive’, when it is sensitive to changes in temperature, usually cold. Such pain/sensitivity lasts for few seconds. Common causes that may lead to hypersensitivity include: • Exposed dentin due to abrasion, attrition, erosion, etc. • Leakage under restorations • Tooth or cavity preparation without adequate water coolant.

WHAT ARE THE DIFFERENT HYPOTHESES PUT FORWARD TO EXPLAIN THE MECHANISM OF DENTINAL HYPERSENSITIVITY? Different theories have been proposed to explain the mechanism underlying Dentin Hypersensitivity such as (Fig. 31.1): • Neural theory (Presence of nerves in dentin) • Transduction theory • Hydrodynamic theory. Of which, the hydrodynamic theory is the most accepted theory for exposed dentin sensitivity.

Neural Theory or Direct Innervation Theory • Earlier it was thought that free nerve endings are present in the entire length of dentinal tubules. Stimuli directly activate the nerve endings causing hypersensitivity. • Nerve fibers were shown to be present in the innermost part of dentinal tubules in circumpulpal dentin. • This hypothesis is not accepted now. • Tooth is usually very sensitive at the Dentino Enamel Junction (DEJ). But the hypothesis that nerve endings are present at the DentinoEnamel Junction has not been corroborated.

Dentinal Hypersensitivity and its Management

Transduction Theory • According to this theory, odontoblast is the primary structure excited by the stimulus and the impulse is transmitted to the nerve endings in the inner dentin. • This is not a popular theory as it has been found that outer part of dentinal tubule contains only dentinal fluid and not cells (odontoblasts). Odontoblastic process is present in the inner portion of dentinal tubules. • Also, there are no neurotransmitter vesicles in the odontoblastic process to facilitate the synapse.

Hydrodynamic Theory • According to this theory, when the exposed dentin of a tooth is subjected to external stimuli such as heat, cold, air blasts, probing with tip of an explorer, it causes rapid displacement of fluid in the dentinal tubules producing pain. This is called “hydrodynamic mechanism of dentin sensitivity.” • The fluid displacement may be inward or outward and it stimulates the pain mechanism in the dentinal tubules by mechanical disturbance of the nerves closely associated with the odontoblast and its process. Mechanical displacement of dentinal fluid affects the nerve endings. Thus nerve endings act as mechanoreceptors. The movement of intratubular fluid influencing mechanoreceptors has been called as the Hydrodynamic theory of Dentin sensitivity. • According to studies done by Brannstrom, the rapid movement of dentinal fluid causes pain in response to osmotic, chemical, mechanical or thermal stimuli. – According to studies done by Matthews, et al:

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– External stimuli produce movement of dentinal fluid causing stimulation of A-delta nociceptive nerve fibers located on pulpal side of the dentinal tubules, producing dental pain. – Outward flow of fluid is found to produce stronger nerve response than the inward movement. – On thermal stimulation, there is rapid movement of fluid into dentinal tubules which causes activation of sensory nerve terminal in the underlying pulp. Heat causes the dentinal fluid flow towards the pulp as heat expands the dentinal fluid faster than it expands the dentin. Cold causes fluid to contract more rapidly than dentin causing dentinal fluid to flow outwards. – Dentinal tubule acts like a capillary tube having an exceedingly small diameter. Dehydration/ Dessication of dentin caused by blast of air or absorbent paper cause capillary forces that produce rapid outward movement of fluid in the tubule. Brannstrom found that dessication (excessive drying) of dentin can theoretically cause outward flow of dentinal fluid at the rate of 2–3 mm/sec.

Fig. 31.1  Hypotheses or theories to explain mechanism of dentinal hypersensitivity: On the left, is the direct innervation theory (Stimuli directly affect the nerve endings in the tubules), in the center is the hydrodynamic theory (Stimuli cause inward or outward movement of fluid in the tubule which causes movement of odontoblast and its process), and on the right side is the transduction theory (Membrane of odontoblast process conducts and impulse to nerve endings in tubules). a: Dentin, b: Predentin, c: Odontoblastic process, d: Odonto­ blast on the right side is the transduction theory (Membrane of odontoblast process conducts an impulse to nerve endings in tubules)

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WHAT IS THE INCIDENCE AND PREVALENCE OF DENTINAL HYPERSENSITIVITY? Incidence and prevalence of Dentinal Hypersensitivity: • More common in females than males. • In cervical region of incisors and premolars, often on the side opposite the dominant hand. • Toothbrush abrasion being the most common cause. • Occurs mostly in third to fourth decades of life. • Decline in prevalence of hypersensitivity in older patients due to decrease in dentinal tubule permeability. • More with cold stimuli (90%) than other stimuli such as chemical (Candy) or mechanical (toothbrushing). • Commonly involved areas: Cervical areas of teeth are commonly affected by Dentinal Hypersensitivity. Facial root surfaces in canines, premolars and molars are particularly affected, especially in the areas of periodontal attachment loss due to their susceptibility to toothbrush abrasion often on opposite side of dominant hand.

WHAT ARE THE PREDISPOSING FACTORS THAT CAUSE DENTINAL HYPERSENSITIVITY? • Movement of fluid in the dentinal tubules is the basic event in the arousal of pain. • Dentin may be hypersensitive due to – Lack of protection by Cementum or Enamel – Loss of smear layer – Hydrodynamic movement of fluids in dentinal tubules. • Pain is amplified when dentinal tubules are open to oral cavity. • Patent dentinal tubules are usually present in areas of hypersensitivity and may result in increased irritation and localized reversible inflammation of the pulp at the sites involved. When the patent dentinal tubules are exposed, ‘A’ fibers innervating the dentinal tubules or located in pulp adjacent to dentinal tubules get activated by stimuli such as blast of air from air/water syringe, scratching the dentin with explorer tip, rapid cooling, or presence of hypertonic solution (sweets). • Thus, Dentinal hypersensitivity may be caused by: – Inflammatory changes in the pulp or – Mechanical changes in the patency of dentinal tubules. Dentinal hypersensitivity may be related to: • Excessive abrasion caused due to vigorous tooth brushing (Mechanical-Abrasion)

• Erosion from dietary or gastric acids (Chemical- Erosion) • Occlusal stresses • Periodontal patients with gingival recession and exposed root surfaces: Periodontal disease causes recession of gingiva. Gingival recession exposes cementum to the oral environment. The thin layer of cementum is lost by toothbrushing or flossing or using tooth picks and dentin gets exposed which may respond to stimuli. • May be increased following Scaling and Root planning. • Dehydration/Dessication of dentinal surface by airblast. • Acid etching of exposed dentin to remove the smear layer opens the tubule orifices and makes dentin more responsive to stimuli such as air blasts and probing.

HOW TO DIAGNOSE DENTINAL HYPERSENSITIVITY? Diagnosis of dentinal hypersensitivity is based on eliciting: • Type of stimuli • Duration of pain • Location • Absence of pulpal symptoms • Absence of radiographic changes. Dentin Sensitivity is not a problem in intact teeth. It is possible to activate neurons with high intensity stimulus during cold testing (vitality test for pulp) with ethyl chloride spray. It represents normal dentinal sensitivity. When the tooth feels more sensitive than the normal, it is called Dentinal Hypersensitivity. Pain is evoked by cold stimuli, mechanical stimuli (probing with an explorer tip), and hypertonic stimuli (sweets). Pain is short, sharp pain in response to stimuli  arising from exposed dentin. Pain is of mild to moderate intensity and patient usually is able to localize the tooth. Symptoms of dentinal hypersensitivity are reversible.

HOW TO MANAGE DENTINAL HYPERSENSITIVITY? Newly exposed dentin may be very sensitive. However, within a few weeks, sensitivity subsides due to: • Gradual occlusion of the tubules by mineral deposits, thus reducing the hydrodynamic forces. • Deposition of reparative dentin over the pulpal ends of the exposed tubules. • Formation of smear layer from tooth brushing or dentinal sclerosis.

Dentinal Hypersensitivity and its Management

Thus in few cases, Dentinal Hypersensitivity resolves without treatment. In other cases that do not spontaneously desensitize, need treatment.

Management of Dentinal Hypersensitivity • Identify the cause or the predisposing condition causing dentinal hypersensitivity. – If the exposed dentin is due to vigorous tooth brushing habit, patient should be educated regarding the right brushing technique, use of soft toothbrush, etc. – If dentin is exposed due to erosion by gastric acids, then its medical treatment is advised to prevent further erosion of enamel. Dietary counselling may help in these cases. It has been found that there is greater loss of dentin when brushing is performed immediately after exposure of tooth surface to dietary acids from citrus fruits. Patients should be informed and cautioned regarding this. – If traumatic occlusion is the cause, then it should be corrected. – If periodontal condition causing gingival recession and exposed root surfaces is the problem, then periodontal therapy along with the treatment of dentinal hypersensitivity. – If recent Scaling and root planning (Periodontal therapy) has resulted in hypersensitivity, patient should be reassured that it will resolve in few days without any treatment or some therapeutic agent may be used for its treatment. – If hypersensitivity is related to recently done Composite restoration in which acid-etching was done (total-etch technique), patient should be reassured that mild postoperative sensitivity will gradually subside, but clinician should also check for occlusal high points in the restoration and other causes of postoperative sensitivity with composites (such as over-drying of dentin, over-etching, faulty technique, moisture contamination, etc.) In few cases, removal of the restoration and re-doing it with correct technique and using Self-etch technique will solve the problem. • Prescribing home-use desensitizing dentrifices and mouthwashes: Use of Desensitizing dentrifices and mouthwashes by the patient for few weeks to months can provide relief from dentinal hypersensitivity. This is specially in cases of Generalized attrition or multiple teeth with mild abrasion. Desensitizing dentrifices and mouthwashes may contain the following agents.

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– 5% potassium nitrate: Potassium reduces the neuronal activity, thus decreasing the dentinal hypersensitivity. Studies have shown that the potassium containing dentrifices reduce the hypersensitivity to cold by about 60%. – 10% strontium chloride: Strontium chloride acts by blocking the dentinal tubules. Studies have found it to be effective by 50–70% in reducing dentinal hypersensitivity. – Fluoride in the form of Sodium Monofluorophosphates has also been found to be quite effective in the management of dentinal hypersensitivity. • Following treatment modalities can be used in the management of dentinal hypersensitivity. – Burnishing of the exposed root surface to form smear layer using an orange wood stick or toothpick. This occludes the open dentinal tubules to some extent and reduces dentinal hypersensitivity. – Application of desensitizing agents: - Desensitizing agents that form insoluble precipitates within the dentinal tubules—Certain soluble salts react with ions in tooth structure and form crystals on the surface of dentin. Examples of such agents include: Oxalate compounds. Oxalate ion reacts with calcium ions in dentin fluid causing precipitation of calcium oxalate in the dentinal tubule. This causes decrease in functional diameter, thereby limiting fluid movement. Potassium ion can reduce nerve activity. Commercially available potassium oxalate solutions to treat sensitive dentin can be used. - Desensitizing agents that occlude the dentinal tubules with precipitated plasma proteins in dentinal fluid. For example, Hydroxyethyl methacrylate (HEMA) with or without Glutaraldehyde. Various therapeutic agents for dentinal hyper­ sensitivity can also be classified as: a. Neural-modulating agents: E.g. Potassium nitrate. b. Tubule-blocking agents: E.g. Strontium chloride, oxalates. – Application of dentin bonding agents: Dentin bonding agents and dentin adhesives reduce sensitivity by forming resin tags and a hybrid layer. For example, Primer of the original Gluma adhesive system (an aqueous solution of 5% Glutaraldehyde, 35% HEMA) marketed as GLUMA desensitizer. It reduces sensitivity by protein denaturation process with concomitant changes in dentin permeability. It has been found to be quite effective in management of dentinal hypersensitivity.

Fig. 31.2  Mind-map to remember all points of dential hypersensitivity

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Dentinal Hypersensitivity and its Management TABLE 31.1  Management of dental hypersensitivity 1. Identify the cause or predisposing condition and take measures to correct it.

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TABLE 31.2  Management of dentinal hypersensitivity (According to Hargreaves and Seltzer, Seltzer and Bender’s Dental Pulp, 2002 edn.)

2. Home-use dentrifices and mouthwashes: •  5% potassium nitrate •  10% strontium chloride •  Fluoride sodium monophosphate

Interventions that reduce dentinal permeability and block dentinal fluid flow Application of materials such as:

Application of:

3. Treatment modalities: •  Burnishing of exposed root surface •  Application of desensitizing agents:   – That form insoluble precipitates within dentinal tubules (oxalate compounds)   – That occlude dentinal tubules with precipitated plasma proteins in dentinal fluid (HEMA with or without glutaraldehyde)

1.  GLUMA dentin bond

1.  Potassium containing dentrifices

2.  Oxalate salts

2.  10% strontium chloride

3.  Isobutyl cyanoacrylate

3.  Fluoride containing medicaments

4. Fluoride-releasing resins or varnishes

4.  Guanethidine 1% solution

  Therapeutic agents:   – Neural-modulating agents, e.g. potassium nitrate   – Tubule-blocking agents, e.g. Strontium chloride, oxalates •  Application of dentin bonding agents: Gluma (5% glutaraldehyde 35% HEMA) •  Composite resin restorations •  Lasers:   – Low-output: GaAlAs   – High-output: Nd:YAG

– Composite resin restoration: Cervical abrasion or erosion (Class V cavity) can be treated by restoring with composite resin restoration. Newer self-etch systems are preferred. The open dentinal tubules are thus sealed preventing pain producing stimuli from reaching the pulp. – Us e of las ers in manag ement of dentinal hypersensitivity: Lasers such as Nd:YAG, CO2 lasers and others have been tried in the treatment of dentinal hypersensitivity. Low-output lasers such as GaAlAs have been found effective in mild to moderate cases of dentinal hypersensitivity. They are thought to cause a transient reduction in action potential mediated by pulpal C fibers but not A-delta fibers. High-output lasers such as Nd:YAG have been found to cause superficial occlusion of dentinal tubules in addition to action potential blockage within the pulp. However, the clinical trials

Interventions that reduce the activity of dentinal neurons

5.  CO2 lasers 6. Coronally positioned mucogingival flaps

conducted and current available evidence does not support the use of lasers for treatment of dentinal hypersensitivity. So, other more conservative and economical treatment modalities are recommended. Management of Dentinal Hypersensitivity has been summarized in Table 31.1. Therapies for management of dentinal hypersensitivity can also be classified as shown in Table 31.2 (According to Seltzer and Bender). A mind-map to remember all points of dental hypersensitivity is given in Figure 31.2.

BIBLIOGRAPHY 1. Bhaskar SN. Orban’s Oral histology and embryology, 11th edn. Mosby; 2001.p.123. 2. Cohen S, Hargreaves KM. Pathways of Pulp, 9th edn. St. Louis: Mosby; 2006.pp.35, 49-50, 487-90, 520-521, 531. 3. Hargreaves KM, Goodis HE. Seltzer and Bender’s Dental Pulp, Quintessence Books; 2002.pp.205-11. 4. Ingle J, Bakland L, Baumgartner J. Ingle’s Endodontics 6, 6th edn. BC Decker Inc, Hamilton; 2008.pp.386-7. 5. Theodore MR, Herald OH, Edward JS. Sturdevant’s Art and Science of Operative Dentistry, 5th edn. Elsevier, Mosby; 2006.pp.268-9.

CHAPTER

32

Lasers in Endodontics

This chapter describes a few aspects of Laser Physics and explains the clinical applications of lasers in Endodontics.   You must know • What is Laser? • What are the Properties of Lasers? • What are the Components of Lasers? • What are the Modes of Laser Light Emission? • How is the Laser Interaction with Biologic Tissues? • Which are the Type of Lasers? • What are the Applications of Lasers in Endodontics? • What are the Advantages and Limitations of using Lasers in Endodontics?

WHAT IS LASER? Laser is an acronym for “Light Amplification by Stimulated Emission of Radiation”. The light beam consists of packets of energy known as photons such as produced by light sources. The actual physical process that takes place within laser device is amplification by stimulated emission of radiation. The radiation that is used for generating laser light is nonionizing and does not produce the effects of X-radiation. In 1960, the ruby laser was developed by Maiman. Lasers were introduced in the field of Endodontics by Weichman in 1971. Applications of lasers in Dentistry (approved by Food and Drug Administration) include: • Removal of diseased gingival tissues and other soft tissue applications • Dental caries removal • As an aid in placing tooth-colored restorations • As an adjunct in Endodontic procedures such as Pulpotomy. Laser is among one of the alternative methods used in Endodontics.

Application of Laser light results in modification or removal of tissue.

WHAT ARE THE PROPERTIES OF LASERS? Dental lasers operate in infrared, visible or ultraviolet range of electromagnetic spectrum. Three unique properties of lasers include: 1. Monochromatic wavelength: Laser light is all the same color (single wavelength). 2. Collimation: The light waves of laser light are parallel to each other. They do not diverge or have very low divergence. 3. Coherence: Waves of light (photons) are all in one phase.

WHAT ARE THE COMPONENTS OF LASERS? Figure 32.1 shows the schematic representation of laser showing its components. • Laser medium: – The construction of a light source based on stimulated emission of radiation needs an active

Lasers in Endodontics

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Fig. 32.1  Schematic representation of laser components

medium such as gas, liquid or a solid material and is contained in glass or ceramic tube (Laser media described later in this chapter). – The medium that produces the beam identifies the laser and distinguishes one laser from the other. • Optical cavity: – It is required to provide amplification in the laser and to select the photons that are travelling in desired direction. – A mirror can be added to each end of the laser medium on the laser optical cavity so that the population of photons can be directed back and forth through the medium stimulating the emission of radiation from multiple excited electrons. Some of the produced photons can pass through one of the mirrors and the resulting light can be used as surgical beam. • Pumping system: – It imparts energy to atoms or molecules of laser medium – Energy in the form of electric current or a flash lamp is applied to the medium.

WHAT ARE THE MODES OF LASER LIGHT EMISSION? Modes of Laser light emission: Laser energy is emitted in different ways with different types of Lasers. These modes of laser emission are shown in Figure 32.2. 1. Continuous wave mode: For example, in Diode laser, energy is emitted in a Continuous Wave Mode. 2. Gated Mode: It is the mechanical interruption of energy emission allowing for better control of thermal emission called as Gated mode. 3. Pulsed mode: The Pulse duration and interval is in millisecond or microsecond. For example, the Nd:YAG and Erbium lasers emit laser energy in pulsed mode. Each pulse has a beginning time, increase and end time referred to as Gaussian progression. Between pulses,

Fig. 32.2  Modes of laser light emission: A : Continuous wave mode B : Gated wave mode C : Pulsed wave mode

Fig. 32.3  Laser interactions with biologic tissues

tissue has time to cool called thermal relaxation time for better control of thermal effects.

HOW IS THE LASER INTERACTION WITH BIOLOGIC TISSUES? • Types of laser interactions when light hits the target tissue—Light can be reflected, absorbed, scattered or transmitted through the tissue as shown in Figure 32.3. – Reflection: It is the phenomenon of a beam of laser light hitting a target and reflecting back due to lack of affinity. It is therefore mandatory to wear protective eye wear to prevent accidental damage to eyes.

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– Absorption: It is the phenomenon of laser energy incident on tissue being absorbed due to affinity thereby exerting its biological effects. – Diffusion: It is the phenomenon of incident light penetrating to a depth in a nonuniform manner with respect to the point of interaction so that the biologic effects are created at a distance from the surface. When the light is scattered, it travels in different directions and energy is absorbed over a greater surface area. This produces less intense and less precise thermal effect. – Transmission: It is the phenomenon by which laser beam passes through the tissue without any affinity and exerting no effect. The interaction occurs between the laser light and the tissue if there is optical affinity between them. (Absorption and Diffusion) The lesser the optical affinity, the more the laser light will be reflected or transmitted. • The effect of laser interaction with tissue depends on: – Laser wavelength – Energy level – Mode of application – Tissue characteristics – Degree of laser energy absorbed or scattered by the tissue. • The biological effects of lasers which can be utilized for their applications in dentistry are: – Photothermal effects: The radiant light is absorbed into heat energy which produces the tissue effect. These effects destroy the cell wall. It has been found that the Gram-negative bacteria are more easily destroyed with less energy and radiation than the Gram-positive bacteria. – Photomechanical effects (including Photoacoustic effects) – Photochemical effects. In Endodontics, the Photothermal and Photomechanical effects result from interaction of different wavelengths on target tissues.

WHICH ARE THE TYPES OF LASERS? Classification of lasers according to their location on the electromagnetic spectrum of light: Different wavelengths of the electromagnetic spectrum include: • Ultraviolet range (140–400 nm) • Visible light (400–700 nm) • Infrared range (700 nm)

Lasers • Visible and invisible: For example, Argon Laser emits visible light (488 or 514 nm) The excimer laser emits invisible light at various wavelengths—ArF 193 nm, KrF 248 nm and XeCl—308 nm • Near, medium and far infrared laser: – Near infrared laser—803–1304 nm. For example, Nd:YAG (1064 nm) which has the depth of penetration in soft tissues up to 5 mm. It delivers laser energy through an optical fiber. Diode laser (810–1064 nm) which has depth of penetration in soft tissues up to 3 mm. Near infrared lasers are not absorbed by hard dentinal tissues. They have no ablative effect on dentinal surfaces. – Medium infrared laser—2780–2940 nm. For example, Erbium, Chromium YSGG (Er, Cr:YSGG; 2780 nm laser) and Erbium:YAG (2940 nm). They are used with flexible, fine tips. They are absorbed by the water content of dentinal tissues. They have superficial ablative and decontaminating effect on dentinal surfaces of the root canal walls. – Far infrared laser—For example, CO2 (10,600 nm) Classification of lasers according to penetration power of beam: • Hard lasers: They have increased penetration power. Examples include: Nd:YAG laser, Argon laser • Soft lasers: They have decreased penetration power. Examples include: Diode laser, He-Ne laser. Classification of lasers according to medium that produces the beam • Gas lasers: Examples are Argon lasers, CO2 lasers • Liquid lasers: Examples are Dye lasers • Solid state lasers: Example is Nd:YAG laser • Semiconductor lasers: Example is Gallium laser

Types of Lasers in Detail The particular properties of each type of laser and the specific target tissue determine which type of laser to be used for various procedures. Different types of lasers may have different effects on the same tissue. Also, same laser can have different effects on different tissues. • CO2 Laser (10.6 microns) – It is highly absorbed by all biological soft and hard tissues. – It is the most effective laser in tissues with high water content. It can be used for soft tissue procedures such as soft tissue surgery, Gingivectomy, Frenectomy, etc.

Lasers in Endodontics

– It has high thermal absorption. So, they are not suitable for drilling or cutting enamel and dentin as damage to dental pulp may occur. • Er:YAG laser (2.94 microns) – It is most efficient for drilling and cutting enamel and dentin. – Its energy is well-absorbed by water and hydroxyapatite. • Nd:YAG laser (1.06 microns) – Nd:YAG photons are transmitted through tissues by water. – They interact well with dark pigmented tissue. – Nd:YAG laser is effective for disinfection of the root canal and soft tissue procedures. – It can be used to treat dentinal hypersensitivity. • Argon lasers (488 or 514 nm) – It has two wavelengths—Blue and Green. Blue wavelength (488 nm) is used mainly for curing of Composite Restorations, Green wavelength (514 nm) is mainly used for soft tissue procedures and coagulation. – They are more effective on pigmented or highly vascular tissues – Delivered through fiberoptic. • Excimer lasers - They function by breaking molecular bonds and reducing the tissue to its anatomic constituents before dissipating the energy as heat. Nd:YAG, Argon and Excimer lasers can be delivered through fiberoptic that provides greater accessibility to different areas and structures in oral cavity.

WHAT ARE THE APPLICATIONS OF LASERS IN ENDODONTICS? • Pulpal diagnosis – Laser Doppler Flowmetry (LDF) is used to assess blood flow in microvascular system. – It can be used to measure blood flow in the dental pulp. – Nd:YAG laser is applied for thermal testing (heat test) Laser Doppler Flowmetry has been explained in Chapter 7, Diagnosis and Diagnostic aids in Endodontics. • Dentinal hypersensitivity: – Lasers used for dentinal hypersensitivity are low output lasers such as He-Ne and GaAlAs lasers and middle output lasers such as Nd:YAG and CO2 lasers. – CO2 lasers seal the open dentinal tubules as well as reduce the permeability of dentinal tubules.

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• Pulp capping – Nd:YAG, CO2, Argon and Er:YAG lasers can be used for pulp capping procedures. • Pulpotomy – FDA has approved the diode laser as an adjunct for removal of pulp tissue in pulpotomy procedure. – Nd:YAG and Argon lasers can be used. • Root canal preparation (Shaping) – Lasers can be used to remove dental pulp and organic debris from the root canal. – Lasers modify the dentinal walls by inducing melting and resolidification cycles that cause enlargement of the root canal walls. • Disinfection of root canals – The potential bactericidal effect of laser irradiation can be effectively utilized in cleaning and disinfection of the root canal system following biomechanical instrumentation. – For disinfection of the root canals, laser energy can be used directly or in combination with a photosensitive chemical, which is activated by low energy laser light to kill the microorganisms (Photodynamic therapy) that aid in distributing the disinfecting solutions more effectively in the root canal system (PhotonInduced-Photoacoustic-Streaming (PIPS). – Pulsed low energy laser emanates propagation of acoustic waves – Studies have shown that Nd:YAG, Argon, Er, Cr:YAG and Er:YAG laser irradiation has the ability to remove debris and smear layer from the root canal walls following biomechanical instrumentation. – Emitted energy is delivered into the root canal system by a. A thin optical fiber (Nd:YAG, KTP-Nd:YAG, Er:YSGG, argon and diode) b. A hollow tube (CO2 and Er:YAG) – The delivery of laser through a flexible optical fiber of 200 microns for canal decontamination has shown positive results. – The properties of laser light may allow a bactericidal effect beyond 1 mm of dentin. – Limitations of intracanal use of lasers a. Laser energy is emitted from the tip of optical fiber or the laser guide and is directed vertically along the root canal but may not be directed laterally to the root canal walls. Thus, laser will not be able to uniformly cover the entire root canal surface. b. There is potential for thermal damage to the periapical tissues.

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c. There is possibility of transmission of laser irradiation beyond the apical foramen in the periapical tissues which may be hazardous in case of teeth which are in close proximity to the mental foramen or mandibular nerve. d. Laser light may not be able to eradicate Endodontic biofilms even on direct laser exposure. – A new Endodontic tip called side-firing spiral tip has been developed to be used with Er:YAG laser, in which delivery of laser is through a hollow tube which allows lateral emission of radiation (sidefiring). It is designed to fit the shape and volume of the root canals prepared using Nickel Titanium

rotary instrumentation. This tip is sealed from its far end, so that there is no transmission of irradiation to and through the apical foramen. – Lasers can be combined with the commonly used irrigants such as 5.25% sodium hypochlorite, 17% EDTA and 10% citric acid for effective cleaning of the root canal system. The action of chelating substances facilitates the penetration of lasers into the dentinal walls up to 1 mm depth and is found to have stronger decontaminating effect than the chemical agents used alone. Laser-activated irrigation has been found to be very effective in removing debris and smear layer from root canals as compared to the traditional techniques and ultrasonics.

Fig. 32.4A  Mind-map of Lasers in Endodontics

Lasers in Endodontics

• Obturation of root canals – Two uses thought of with lasers for obturation of root canals include: a. To use laser irradiation as a heat source for softening gutta-percha for use as obturating material b. To condition the dentinal walls before placing an obturating bonding material. – Laser-assisted root canal filling procedure that was first performed involved using Argon 488 nm laser that was used to polymerize a resin that was placed in the main root canal.

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– It was demonstrated by Kimura et al that Nd:YAG laser was useful for reduction of apical leakage. • Endodontic retreatment – Laser irradiation can be used to remove foreign material from the root canal system, which may otherwise be difficult to remove by conventional methods. – Studies have shown that Nd:YAG laser irradiation is an effective technique for removal of root canal filling materials and has advantages over conventional methods. Er:YAG laser can also be used for the same purpose.

Fig. 32.4B  Mind-map of “Laser application in Endodontics”

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• Apicectomy – The dentin of the apically resected roots is more permeable to fluids than the dentin of nonresected roots. – FDA has approved the diode laser for apicectomy. – Advantages of using lasers for periapical surgery are improved hemostasis and concurrent visualization of the operative field. – When Er:YAG laser is used in a low output power in apical surgery, smooth and clean resected surfaces devoid of charring were observed. – Laser converts the apical dentin and cementum structure into a uniformly glazed area which does not allow egress of microorganisms through dentinal tubules and other openings in the apex of the tooth. • Bleaching of teeth – Argon laser is used for bleaching of teeth by chemical oxidation process. – CO2 laser is used to enhance the bleaching effect caused by Argon laser.

WHAT ARE THE ADVANTAGES AND LIMITATIONS OF USING LASERS IN ENDODONTICS?

Limitations • Root canals are rarely straight. They are usually curved at least in two dimensions. Manual Endodontic instruments (files) can be curved to follow the curvature of the root canal. But Lasers travel in straight path. So, laser probes need to be fabricated that cause laser light to emerge laterally, uniformly interacting with the root canal walls. • Root canal preparation using lasers has not been proved to be more effective than the mechanical shaping procedures. • There are hazards related to rise in temperature caused by interaction of laser with the tissue. The increased temperature can char the root canal space causing damage to the tooth and its surrounding hard and soft tissues. The bone surrounding the tooth may be irreversibly injured resulting in ankylosis. • The melting and solidification cycles while root canal preparation using lasers have not shown to have any positive effect on the clinical outcome. Figure 32.4A gives the mind-map to remember all points of Lasers in Endodontics, and Figure 32.4B gives the mind-map of Laser applications in Endodontics.

Advantages

BIBLIOGRAPHY

• • • • •

1. AAE Position Statement on Use of Lasers in Dentistry. American Association of Endodontists. 2012. 2. Cohen S, Hargreaves KM. Pathways of Pulp, 9th edn. St. Louis: Mosby, 2006.pp.20, 279-80, 529-31, 612-3, 852. 3. Ingle J, Bakland L, Baumgartner J. Ingle’s Endodontics 6, 6th edn. BC Decker Inc, Hamilton, 2008.pp.857-66. 4. Kimura Y, Wilder-Smith P, Matsumoto K. ‘Lasers in Endodontics-A Review’, International Endodontic Journal. 2000;33:173-85. 5. Olivi G, Crippa R, Iaria G, Kaitsas V, DiVito E, Benedicenti S. “Laser in Endodontics-Part I”, Roots 1. 2011.pp.06-9.

There is no need of anesthesia There is no noise in contrast to the noisy dental drills Less bleeding Less chances of infection Results in faster healing.

CHAPTER

33

Endodontic Practice: Ethics and Legal Responsibilities

This chapter outlines the ethics in dentistry and explains the legal responsibilities of the clinician to practice Endodontics with optimum standard of care.   You must know • What is Dental Ethics? • What are the Principles of Ethics? • What is Standard of Care? • What is Dental Negligence and Malpractice? • What are the Legal Responsibilities of the Clinician while Performing Endodontics?

WHAT IS DENTAL ETHICS? The word “Ethics” is derived from Greek word ‘Ethos’ meaning custom or character. Ethics is nothing but philosophy of human conduct. Dental ethics is a moral concept which encompasses rules and standards that govern the dentist to perform his duties with the expected standard of care. Ingle’s Endodontics 6th edition gives the full form of the word ‘ETHICS’, which can be explained as: E = Expertise Clinician must provide full attention and expertise in treating each and every patient. T = Truthful Clinician must be truthful in all the communications made with the patient regarding diagnosis, treatment, prognosis, etc. H = Honesty Clinician is expected to be honest in all dealings. I = Integrity Clinician must exhibit reliability so that patients can trust him/her completely. C = Compassion Clinician must show concern towards each and every patient. S = Sagacity

A prudent clinician is reasonably careful while treating each patient. Dentists are guided by the codes of ethics provided by the governing body such as the American Dental Association (ADA), Indian Dental Association (IDA), Dental Council of India (DCI), etc.

WHAT ARE THE PRINCIPLES OF ETHICS? • Recommend the therapy, which is best for the patient • Minimize the potential harm to the patient • Avoid placing a patient at an unreasonable risk of harm. The principles of ethics are listed in Figure 33.1.

WHAT IS STANDARD OF CARE? Definition: As given in Ingle’s Endodontics 6th edition. Standard of care is defined as “that reasonable care and diligence ordinarily exercised by similar members of the profession in similar cases in like conditions given due regard for the state of the art.” For good Endodontic practice, the clinician should be reasonably careful and must possess and exercise reasonable degree of skill and knowledge. Clinicians must strive to do their best and practice Endodontics at the highest level.

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2. Despite reasonable schooling, training and continuing education, the clinician acts with unreasonable carelessness or imprudently fails to act as a reasonably careful clinician should act.

Incidents of Negligence and Malpractice in Endodontic Practice (Malpractice Cases) Slips of Drill • It can cause injury to oral soft tissues such as tongue, lip or cheek – Clinician needs to inform the patient. Then provide treatment for the injured soft tissues and if need be,  patient has to be referred to an oral surgeon and the dentist bears the expenditure. After healing of the injured tissues, the dentist can continue with the root canal treatment.

Incorrect Tooth Treatment

Fig. 33.1  Principles of ethics

It is the prudent clinician who sets the standard of care. Endodontists, as specialists, set a higher standard of skill, knowledge and care as compared to general practitioner while practicing Endodontics. Thus, Endodontists set the standard for routine Endodontics. So if the standard cannot be met the general practitioner should refer the patient to an Endodontist rather than performing procedures that are beyond his training or competency to avoid performing treatment that is below the specialist’s standard of care.

WHAT IS DENTAL NEGLIGENCE AND MALPRACTICE? Violation of standard of care by a provider that results in harm to the patient is called dental negligence. Professional negligence arising out of the doctor-patient relationship is termed as malpractice. In simple words, negligence is nothing but carelessness or inattentiveness and malpractice is the layman term given to professional negligence. ‘Pathways of Pulp’ — Stephen Cohen’s 9th edition has given two reasons for dental negligence to occur: 1. When the clinician does not possess a reasonable degree of education and training to act prudently or

• It can occur due to failure in localizing the source of Endodontic pain. Sometimes a vital tooth will be sacrificed due to wrong judgment and diagnosis. – Clinician needs to be compassionate towards the patient and he may compensate for the error by not taking payment for the treatment performed.

Swallowing or Aspiration of an Endodontic Instrument • This can occur due to failure to use rubber dam – Clinician must inform the patient. Refer the patient for medical care to find the position of the instrument and take appropriate measures.

Broken/Separated Instruments (Files) • Files can break in the root canal because of overzealous or improper use or sometimes due to defective manufacture of the file. • Instrument separation is the problem that occurs usually with Ni-Ti instruments due to fatigue, if it is used for more than 1 to 2 times. Instrument binds and separates inadvertently. • Instrument separation can be considered as an unfortunate mishap and not negligence or malpractice – Patient should be informed about the mishap. The unbroken end of the file should be saved in a coin envelope and placed in patient’s treatment record. Patient should be referred to an Endodontist for microscopic retrieval of the separated file or at least

Endodontic Practice: Ethics and Legal Responsibilities

patient should be informed that the file is going to be left behind in the root canal and the treatment completed. There is potential for leakage to occur but it has been found that most of the times teeth with separated files may remain asymptomatic and functional for many years.

Perforations • Iatrogenic perforation can occur during entry to canal system due to improper bur angulation or due to overzealous use of Endodontic instruments resulting in stripping or perforation of canal wall or during post space preparation. • Complication of perforation is the potential for secondary periodontal involvement resulting in loss of tooth, if untreatable. So immediate repair of perforation is to be carried out to close the communication between root canal system and periodontal tissues, for the tooth to have a favorable prognosis. – Patient should be informed about the mishap. Assure the patient that the clinician is going to use newer materials (such as MTA) that can predictably seal the defect in the same appointment and will follow-up the case closely.

Use of Silver Points for Obturation • Current use of silver points for obturation is considered to be below standard of care.

Use of Paraformaldehyde-based Root Canal Sealers • Overextension of such sealers can result in permanent paresthesia. Use of such a material is unsafe and should be avoided. – If the clinician has used this kind of sealer and overextension occurs, patient should be informed and patient be referred to an Endodontist for retrieval of the overextended sealer before it sets.

Overextensions • Faulty technique can cause overextension of root canal filling material that results due to over instrumentation, breaking the apical seal. • Permanent harm is unlikely if there is slight over extension. But if gross over extension occurs contacting the vital structures such as inferior alveolar nerve or sinus it can cause permanent consequences. • Slight to moderate overextensions often repair themselves, so patient need not be informed, only a note

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made on patient’s record about it and patient should be closely observed with follow-up visits to rule out severe postoperative pain or development of any pathology like cyst around the overextended material.

Use of Screw Posts Current use of active posts such as screw posts is considered to be unreasonable due to the potential risk of root fracture if the screw is turned more. Instead, passive posts serve as better alternative.

Endodontic Treatment Failure There is inherent risk of Endodontic failure (about 5–10%) in spite of adequate Endodontic care. But most of the times, Endodontic failure is the result of contributing negligent factors such as inadequate isolation of tooth, procedural mishaps such as perforations, transported canals, over instrumentation, overextension, underextension or leaking coronal restorations resulting in reinfection of root canal, etc. • Patient should be informed about non-negligent failure of treatment and risk of complications that can result in failure, before the treatment is initiated so as to avoid patient disappointment later. Besides the above mentioned incidents, various other procedural mishaps can occur during treatment, which are discussed in Chapter 20: Endodontic Mishaps–Management and Prevention. Some may be termed as unfortunate accidents whereas some are a result of dental negligence. Most important is to inform the patient when such an accidental or negligent error occurs regardless of whether the error can be corrected.

WHAT ARE THE LEGAL RESPONSIBILITIES OF THE CLINICIAN WHILE PERFORMING ENDODONTICS? Figure 33.2 gives the list of legal responsibilities of clinician.

Good Record Keeping Clinician must document each and every patient’s details and maintain Endodontic therapy record. • Endodontic therapy record must contain: – Patient’s detailed case history including personal information, chief complaint, medical and dental history – Various findings of clinical examination – Good quality radiographs

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Fig. 33.2  Legal responsibilities of clinician

– – – –

•

•

• • •

Details of referral to other specialists Diagnosis Proposed treatment plan and informed consent Treatment provided: Emergency or elective treatment given along with the date of visit, any problems encountered or any complications that occurred during treatment. – Drug prescriptions – Any missed appointments and stated reasons for the same – Prognosis – Findings of follow-up visits – Payment details. Nowadays with increased use of computers in dental clinic, electronic records are being maintained. Clinician must have back up files for all patient records and confidentiality of patient information must be maintained by various means of protection. Endodontics includes use of several radiographs — pretreatment, intratreatment, post-treatment and follow up radiographs. Radiographs that lack diagnostic quality should be retaken and all the radiographs should be retained. Records should be complete, accurate and well maintained. Records can serve as means of communication among healthcare professionals whenever required. Valid information in the Endodontic therapy records can serve as an evidence to protect the clinician, confirming that accurate diagnosis and proper treatment were provided, in case of a dental malpractice claim against the clinician.

Informed Consent Before the Endodontic treatment is performed, patient must be informed about the benefits, risks, treatment plan and alternatives to Endodontic treatment. Informed consent form should be signed by the patient indicating that patient

has understood all aspects of treatment and accepts the recommended treatment. Also, any subsequent changes in the proposed treatment should be discussed with the patient and an entry made in the consent form to be signed by the patient indicating continued acceptance by the patient.

Referral to Specialists For a competent ethical practice, the clinician must know his limitations. The general practitioner should refer the case to an Endodontist if it is complicated or has a moderate to high difficulty level and will require procedures that are beyond the general practitioner’s training or competency. Before performing Endodontic treatment that the referring clinician has recommended, the Endodontist must undertake an independent diagnostic and radiographic examination of the treatment area and the proposed treatment plan and any associated medical and dental history rather than relying solely on the referring clinician.

Continuing Education A clinician is legally obligated to be updated about the current knowledge and recent technological advances in the field of Endodontics. So, the clinician must attend continuing education courses to update his knowledge and clinical skills.

Accepting Research-based Endodontic Advances Many new dental products and techniques are being constantly introduced to improve the quality and success of Endodontic therapy. A reasonable clinician should review the Endodontic advances and adopt a particular product or technique only if it is well-accepted and proved by research. Clinician must accept the research based facts, which might require: • Giving up those materials and techniques in Endodontics which had been in use for years but research has now

Endodontic Practice: Ethics and Legal Responsibilities

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Fig. 33.3  Mind-map to remember the legal responsibilities of clinician

proved them to be inappropriate or inadequate for root canal therapy. For example, giving up step back technique for root canal instrumentation (cleaning and shaping/biochemical preparation), use of silver points for obturation. • Adopting newer materials and techniques in Endodontics which have proved to be beneficial in root canal therapy. For example, adopting crown-down approach for root canal cleaning and shaping, also use of Nickel-Titanium instruments, etc.



Figure 33.3 gives the mind-map to remember the legal responsibilities of clinician.

BIBLIOGRAPHY 1. Cohen S, Hargreaves KM. Pathways of Pulp, 9th edn. St. Louis: Mosby. 2006.pp.400-52. 2. Ingle J, Bakland L, Baumgartner J. Ingle’s Endodontics, 6th edn. BC Decker Inc, Hamilton. 2008.pp.86-103.

CHAPTER

34

Regenerative Endodontics

This chapter gives an overview of the upcoming field of Dentistry called Regenerative therapy in relation to Endodontics, that can bring about regeneration of functional pulp tissue and regain vitality in a necrotic immature young permanent tooth and also describes the different terminology related to Regenerative Endodontics.   You must know • What is Regenerative Endodontics? • What is Tissue Engineering? • What are the Mechanisms and Clinical Procedures Related to Regenerative Endodontics? • What is the Triple Antibiotic Paste? • What are the Advantages and Limitations of Revascularization Procedure Over Apexification Procedure for a Necrotic Immature Permanent Tooth with Open Apex? • What are the Clinical Considerations for Regenerative Endodontics? • What is the Protocol for Revascularization Endodontic Therapy? • What are the Clinical Measures for Assessment of Endodontic Revascularization Treatment Outcome?

INTRODUCTION Regenerative Dentistry is an evolving field of dental care. The goal of Regenerative Dentistry is to induce biologic replacement of dental tissues and their supporting structures. In the last few decades, there have been lot of advancements in biologic therapies that apply growth and differentiation factors which hasten or induce natural biologic regeneration. Scope and application of Regenerative Dental Procedures has advanced to include: • Guided Tissue Regeneration (GTR) • Guided Bone Regeneration (GBR) • Application of platelet-rich plasma for bone augmen­ tation. • Emdogain for regeneration of periodontal tissues • Recombinant human Bone Morphogenic Protein (rhBMP).

• Use of Fibroblast Growth Factor 2 (FGF-2) for periodontal tissue regeneration. The potential of these therapies for dental practice is being envisioned to include Endodontics. For example: • Pulp, Dentin and Enamel can be regenerated using scaffold material and stem cells. • Tooth crowns can be regenerated using the primordium of embryonic oral epithelium and adult bone marrow stem cells. • Stem cells isolated from extracted third molars can be used to regenerate tooth roots and periodontal ligaments.

WHAT IS REGENERATIVE ENDODONTICS? Definition “ Regenerative Endodontics has been defined as biologically based procedures designed to replace damaged structures such as dentin, root structures, and cells of the pulp-dentin complex.” (Cohen’s Pathways of Pulp, 10th edn. p. 602).

Regenerative Endodontics

• From a biologic perspective, goal of Endodontics is to prevent or treat apical periodontitis. This goal can be accomplished by either: – Maintaining pulpal health in cases of pulpal inflammation or – Regenerating healthy pulp tissue in cases of pulpal necrosis. The objective is to regenerate a functional and healthy pulp-dentin complex. • In case of immature (incompletely developed) young permanent tooth with open apex, when pulp necrosis occurs, its management is challenging due to – Wide blunderbuss apex with lack of apical stop. – Risk of extrusion of irritants into the periapical area. – Thin dentin walls that are difficult to debride and are prone to subsequent cervical fracture. – If extraction of the tooth is done, then restoration is a problem as implants are contraindicated in young patients with growing craniofacial skeleton. In such challenging cases, regenerative Endo­ dontic therapy is an alternative treatment option that aims at regenerating functional pulp tissue that brings about completion of root development and restoration of function.

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Fig. 34.1  Tissue engineering triad

• Stem cells • Growth factors • Scaffolds.

Stem Cells Stem cells are relatively undifferentiated cells capable of self-renewal/expansion by continuously dividing many times.

Types of Stem Cells • Stem cells can be classified as:

WHAT IS TISSUE ENGINEERING? According to American Association of Endodontists, “Tissue Engineering is an interdisciplinary field that integrates the principles of biology and engineering to develop biological substitutes that replace or regenerate human cells, tissues or organs in order to restore or establish normal function.” Regenerative Endodontics is rapidly advancing field based on the principles of Regenerative Medicine and Tissue Engineering, which utilizes three key elements, referred to as ‘Tissue engineering triad’ (Fig. 34.1), including:

• Stem cells can differentiate into specialized cell types. Based on their range of differentiation (Potency), stem cells can be classified as:

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• Based on the source of stem cells, they can be classified as:

– The sourcing of embryonic stem cells is unsuitable for clinical development due to legal and ethical and medical (tissue rejection) issues. So, the researchers are now focusing attention on developing stem cell therapies using postnatal stem cells. The postnatal stem cells are derived from patient themselves or their close relatives. – Using stem cells to regenerate entire tooth may not be practically possible as it takes very long time (many years) even for natural development of teeth. But, within a patient’s existing permanent tooth, a functional pulp-dentin complex may be regenerated so that it can carry out the natural functions including formation of replacement dentin, tissue immunity and neural sensation. – Many postnatal mesenchymal stem cells that can differentiate into odontoblast-like cells have been isolated including:

– Stem cells can be identified and isolated from mixed cell population using various techniques such as staining cells with specific antibody markers and flowcytometry, immunohistochemical staining, etc.

Growth Factors/Morphogens • Growth factors are proteins that bind to cell receptors and act as signals to induce proliferation and/or differentiation of cells. • Growth factors trigger the differentiation of selected mesenchymal stem cells into odontoblast-like cells. • Growth factors found in dentin and platelets have been utilized in the Regenerative Endodontic Procedures. • It has been found that application of dexamethasone combined with Vitamin D3 increases the differentiation of human dental pulp cells into odontoblast-like cells. Other examples of the growth factors include: – Bone Morphogenetic Protein (BMP) derived from bone matrix which brings about differentiation of osteoblasts and bone mineralization. It is used to induce stem cells to synthesize and secrete mineral matrix – Fibroblast Growth Factor (FGF) can promote proliferation of many cells. So, it is used to increase the stem cell numbers. – Platelet Derived Growth Factor (PDGF) is obtained from platelets and endothelial cells. It promotes proliferation of connective tissue cells. It can also be used to increase stem cell numbers.

Scaffolds • Scaffolds organize the cells into correct spatial position and regulate proliferation, differentiation and vascularization. • Appropriate scaffold might bind and localize the cells selectively. • Scaffolds contain growth factors and undergoes biodegradation over time. • Blood clot, dentin and Platelet Rich Plasma have been utilized as scaffolds in few Regenerative Endodontic Procedures. • Classification of scaffolds:

Regenerative Endodontics



Beneficial properties of PRP (Platelet Rich Plasma) include: • Autologous • Easy to prepare in dental setting • Forms 3-dimentional fibrin matrix.

•

WHAT ARE THE MECHANISMS AND CLINICAL PROCEDURES RELATED TO REGENERATIVE ENDODONTICS? Terminology • Apexification: “Apexification is defined as a method to induce a calcified barrier in a root with an open apex or the continued apical development of an incompletely formed root in teeth with necrotic pulp tissue.” (Pathways of Pulp, 10th edn.p.608) • Apexogenesis: “Apexogenesis is defined as vital pulp therapy procedure performed to encourage continued physiologic development and formation of the root end.” (Pathways of Pulp, 10th edn.p.608) • Maturogenesis: Maturogenesis is the term used to describe the outcome of revascularization procedure indicating that a stage is set for physiologic root development. (Pathways of Pulp, 10th edn.p.608) • Revascularization: “Revascularization is defined as the restoration of vascularity to a tissue or organ.” (Pathways of Pulp, 10th edn.p.608) Endodontic Revascularization Treatment aims at regaining the vitality and vascularity of pulp tissue in a necrotic root canal of an immature permanent tooth with open apex. • Guided Tissue Regeneration (GTR): It is induced or guided regeneration of the tissues. The biologic tissue that fills up the pulp space after the Regenerative Endodontic Procedures (REPs) may be dental pulp or pulp-like tissue. The desired outcome of Regenerative Endodontic Procedures (REPs) is regeneration of pulp-dentin complex. Till date, most of the studies published, can be best described as “Revascularization” procedures, that attempt to regenerate biologic tissues (that may not necessarily replicate the pulp-dentin complex) and bring about revascularization within the root canal space.

WHAT IS THE TRIPLE ANTIBIOTIC PASTE? • The Triple Antibiotic Paste is the mixture of Ciprofloxacin/ Metronidazole/Minocycline (CMM) in the ratio of 1:1:1. Hoshino and Colleagues greatly contributed to the

• •

•

•

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development of this paste and this paste was originally used by Banchs and Trope. It is the medicament used to disinfect the root canal space. It can be used as an adjunct to the revasculari­ zation procedure for necrotic pulp space of immature permanent tooth with open apex as it creates a favorable environment for ingrowth of vasculature and regenerative cells by reducing or eradicating bacteria from the root canal space. Research studies show that this antibiotic combination has high efficacy in eradicating the bacteria from infected dentin of root canals. The disadvantage of using this paste is that: There is potential for Minocycline staining of the crown. This can be minimized by restricting the drug below CEJ. If such staining occurs, then walking bleach method using sodium perborate can be used to manage discoloration. This combination is less commonly used in Dentistry. So it needs additional review. Calcium hydroxide or Formocresol are used instead of the triple antibiotic paste sometimes. Also, this paste is not approved by the US Food and Drug Administration.

WHAT ARE THE ADVANTAGES AND LIMITATIONS OF REVASCULARIZATION PROCEDURE OVER APEXIFICATION PROCEDURE FOR A NECROTIC IMMATURE PERMANENT TOOTH WITH OPEN APEX? Advantages With revascularization procedure, there is increased likelihood of: •

Increased root length

•

Increased root wall thickness

}

Completion of root development

• Increased or maintained root strength. Traditional apexification procedure using calcium hydroxide has been found to affect mechanical properties of root dentin reducing the root strength, making it prone to fracture. Also, for apexification using calcium hydroxide, multiple appointments are needed for its reapplication and time taken to form calcified bridge is about 3–24 months. However, with the advent of Mineral Trioxide Aggregate (MTA), these limitations of calcium hydroxide apexification have been overcome as it is found to form a cementum-like hard bridge in relatively shorter duration of time and

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also requires fewer patient appointments. However, with both of these apexification procedures, root development is not fostered and tooth remains prone to subsequent cervical root fractures.

Limitations • Although Revascularization procedure causes increased root thickness in midroot and apical root, but not in cervical area, making the tooth prone to fracture in that area. • Regenerative Endodontic Procedures are limited to immature teeth as open apex is a ready source of stem cells. However, its long-term goal should be to treat mature permanent teeth as well. • There is ongoing research and trials for the various Regenerative Endodontic Procedures (REPs). But till date, no randomized controlled clinical trials have been published to evaluate the various Regenerative Endodontic Procedures (REPs) and their potential adverse events. Also, in case of Regenerative Endodontic therapy in humans, histological evaluation of the treatment outcome is not possible. • Case studies show that with Calcium hydroxide and MTA apexification, success rates have been as high as 95%. For Regenerative procedures, there is ongoing research still going on.

WHAT ARE THE CLINICAL CONSIDERATIONS FOR REGENERATIVE ENDODONTICS? • Age: Young patient. Younger patients have greater healing capacity or stem cell regenerative potential. • Permanent tooth with immature apex. The large diameter of the immature (open) apex may have rich source of mesenchymal Stem Cells of the Apical Papilla (SCAP). • Diagnosis of pulp necrosis in such incompletely formed/ immature permanent tooth with open apex. • Minimal or lack of instrumentation of dentinal walls. Since the dentinal walls are not instrumented, smear layer is not generated that could otherwise occlude the dentinal walls or tubules. • Use of an intracanal medicament. Usually the Triple antibiotic paste is left in root canal space for few days or weeks. • Creation of a blood clot in the canal that might serve as a protein scaffold and induces 3-dimensional ingrowth of tissue. Figure 34.2 lists these considerations in the form of a mind-map.

Fig. 34.2  Clinical considerations for Regenerative Endodontics

WHAT IS THE PROTOCOL FOR REVASCULARIZATION ENDODONTIC THERAPY? Revascularization Protocol Case Selection Young patient with incompletely developed permanent tooth with open apex that gives negative response to pulp responsiveness testing.

Informed Consent Inform patient and guardian about: • The number of appointments-2 or more and the potential benefits of the treatment. • Adverse effects that may result from the procedureMinocycline staining of crown. • There may be lack of response to treatment • Alternative treatment options: MTA apexification, no treatment or extraction. • Possible post-treatment symptoms.

Procedure First appointment • Profound anesthesia • Isolation with rubber dam • Access cavity preparation • A small k-file such as no. 10 or 15 is used to scout the root canal system and determination of working length using radiograph or paper point method. • Copious irrigation of root canal system using 20 mL of 3–5% NaOCl followed by 20 mL of 0.12–2% Chlorhexidine with saline wash in between the two to prevent the formation of brownish-orange precipitate. Irrigation should be done using side-vented irrigating needle slowly and carefully so as to avoid or minimize the irrigants passing through the open apex.

Regenerative Endodontics

A

B

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C

Figs 34.3A to C  Schematic representation of pulp regeneration: (A) Immature nonvital permanent tooth with necrotic pulp, SCAP: Stem cells from apical papilla; (B) Following antimicrobial medicament, in the second appointment, the canal is over-instrumented to cause bleeding upto cervical level. Over the blood clot, colla plug and MTA seal and coronal seal with composite restoration; (C) Pulp regeneration is expected that causes completion of root formation

• The root canal system is dried using sterile paper points. • Delivery of antimicrobial medicament such as triple antibiotic paste or calcium hydroxide into the root canal space. • The tooth is sealed with a temporary cement (e.g. Cavit). Second Appointment (Figs 34.3A to C) Scheduled after 3–4 weeks • Patient is assessed for resolution of signs and symptoms, such as pain, swelling, sinus tract, etc. that may have been present during the first appointment. • If the resolution of signs and symptoms has not occurred, the antimicrobial treatment is repeated and patient recalled after few weeks. • If resolution of signs and symptoms has occurred, then patient is anesthesized using 3% Mepivacaine. (Local anesthetic containing vasoconstrictor is not used as in this appointment revascularization-induced bleeding is to be evoked. 3% Mepivacaine facilitates the ability to trigger bleeding into the root canal system.) • Rubber dam isolation of tooth and re-establishment of coronal access. • Copious, but slow and careful irrigation with 20 mL NaOCl along with gentle agitation with small k-file to remove the antimicrobial medicament. • Root canal system is dried using sterile paper points. • A small k-file is placed few mm beyond the apical foramen to slightly lacerate the apical tissue causing bleeding up to 3 mm from the CEJ. • Insert a small piece of colla-plug into the root canal system to serve as resorbable matrix and to restrict MTA positioning (Fig. 34.3B) • Place MTA in the thickness of 3 mm (Fig. 34.3B) • Achieve good coronal seal using a permanent restoration (Fig. 34.3B).



Patient is recalled after 12–18 months for follow-up. Successful outcome is that pulp regeneration occurs in the canal that causes completion of root formation with increase in root length and wall thickness (Fig. 34.3C).

WHAT ARE THE CLINICAL MEASURES FOR ASSESSMENT OF ENDODONTIC REVASCULARIZATION TREATMENT OUTCOME? Assessment of Endodontic Revascularization treatment outcome: • Clinical – Lack of signs and symptoms – Clinical evidence of functioning vital tissue in the root canal. – Pulp testing methods such as heat, cold, electrical, laser Doppler flowmetry suggestive of asymptomatic tooth that does not require retreatment. • Radiographic – Radiographic appearance of increased root wall thickness that could be due to ingrowth of cementum, bone, or a dentin-like material. – Healing of periradicular tissues and progression of root development. – Increase in root length.

BIBLIOGRAPHY 1. Colleagues for Excellence newsletter Regenerative Endodontics www.aae.org/colleagues, Spring 2013. 2. Hargreaves KM, Law AS. Regenerative Endodontics. Chapter 16. Pathways of the Pulp, 10th edn. Hargreaves KM, Cohen S, Mosby Elsevier, St Louis, MO. 2011.pp.602‐19. 3. Peter E Murray, Franklin Garcia-Godoy, Kenneth M. Hargreaves, ‘Regenerative Endodontics: A Review of Current Status and a Call for Action’, JOE. 2007;33:4. 4. Rudolf Jaenisch, Richard Young, ‘Stem cells, the Molecular Circuitry of Pluripotency and Nuclear Reprogramming’, “Cell” Press. 2008;132(4):667-82.

Index Page numbers followed by f refer to figure and t refer to table.

A

B

Acellular cementum 16 Actinomyces israelii 375 Air emphysema 354 Alara, principles of 112 Alkaptonuria 384 Allergy 140 Alveolar abscess acute 74, 328 chronic 76 Alveolar bone proper 17 supporting 17 Amalgam 435 restoration 458 Amelogenesis imperfecta 384 Anesthesia, evaluation of 315 Antibiotic paste 503 Anticurvature filing 254 Anxiety, management of 312 Apexification 446, 503 calcium hydroxide 448f Apexogenesis 503 Apical abscess acute 74 chronic 76 Apical canal transportation, type III 349 Apical perforation 349f Apical periodontitis 74 acute 72 chronic 74, 331 Apical third of root anatomy of 25f canal, instrument in 343f Apical-root fracture 410 Apical-third filling 307 Arterioles 11 Arteriovenous anastomoses 11 Asymptomatic irreversible pulpitis 68 Axial wall extension 213, 218 in maxillary molar 208f Azithromycin 319

Bacterial virulence factors 89, 90f Bacteria-tight seal 406 Bacteroides forsythus 415 Bacteroides melanogenicus 87 Barbed broaches 172f Barodontalgia 64 classification of 64 Bayonet-shaped canals 227f Bioactive glass 276 Biomaterial centered infection 95 Bite test 123, 124 using cotton roll 124f Bleaching chemistry of 384 contraindications of 388 material 391f points of 399f role of 386 Bleaching of vital teeth 390 extracoronal 389f technique for 389 Bone cyst 118 Bone forming cells 16 Bone morphogenetic protein 502 Bone-resorbing cells 16 Bur 163 long shank round 163f round 163f safe-ended 163f sharpness of 58 transmetal 163f

C Calcibiotic root canal sealer 292 Calcium hydroxide 273, 274, 275f, 307, 406, 441, 442, 447, 464 compounds 442 containing sealers 291 in canal, application of 275 points 274

pulpotomy 446 with iodoform 275f Calcium phosphate cement obturation 308 Camphorated parachlorophenol 276 Canal blockage 345 Canal obstructions, removal of 381 Canal orifices 20, 20f, 213 flaring of 204f Canal preparation 244 balanced force technique of 252 hybrid technique of 253 Canal system, type of 25 Candida 267 Candida albicans 415 Carbamide peroxide 388 Carbide bur, safe-ended 164f Carbon fiber-reinforced epoxy resin posts 365 Cardiac pacemaker 168 Caries and defective restorations, removal of 203f Caries causing pulpitis 53f Caries detector dye 125f, 162f Caries in dentin 53f in enamel 53f Carious dentin inner 52f outer 52f Cavity design, poor access 229, 337 Cavity preparation 200, 406 challenging access 226 steps of 207 Cavity walls 167f, 203, 204 Cells of alveolar bone 17 Cells of pulp 10 Cellular cementum 14 Cemental dysplasia 118 Cementoblasts 16 Cementodentinal junction 8, 26, 237, 282 Cementoenamel junction 202

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Cementum 14 and periodontal ligament 6 types 14 Central nervous system 312 Cephalosporins 319 Ceramic veneer, use of 400 Cervical invasive resorption 480 Champagne bubble test 209f Chlorhexidine digluconate 270, 275 for endodontic use 270f Chloropercha 299 Chronic abscess or phoenix (rebirth) 331 Ciprofloxacin 319 Clindamycin 319 Cohen’s pathways of pulp 360 Compartment syndrome 351 Complete roof removal 218 Complete/cervical pulpotomy 445 Composite resin core 368 Composite resin restorations 386, 392, 487 bonding strength of 398 Composite resin system (retroplast) 436 Composite restoration discolored 386f in both teeth 396f use of 400 Core built-up material 369f Core materials 282, 283 for restoration of endodontically treated teeth, classification of 190 types of 367 Core restoration 360 Coronal disassembly 378 Coronal leakage 415 Coronal pulp 19, 20f Coronal root fractures 410 Coronal seal, methods to enhance 310 Crown fracture 404 complication of 406f treatment of 406f Crown or root, fractured 329 cause 329 classification 329 signs 329 symptoms 329 Crown-down technique 251f Crown-root fracture 330f C-shaped canals 26 classification of 27f, 28, 28f Cytokines 133

D Debridement of canal, incomplete 342f Deciduous molar 455f Defense cells 10 Dendritic cells 11, 54 Dens evaginatus 32 Dens in dente 31 in maxillary left central incisor 31f Dens invaginatus 31 Dental biologic tissues changes during inflammation 134 Dental caries 85f sequel of 53f Dental ethics 495 Dental health care personnel 192 Dental history 100 past 101 Dental hypersensitivity, management of 487t Dental illness 100 Dental infection to maxillary sinus 103f Dental lamina primary 6 role of 6 Dental lasers 488 Dental loupes 159 Dental negligence and malpractice 496 Dental operating microscope 159, 163, 206f head portion of 161f Dental operatory 193 Dental pain 101 from maxillary sinus 102f of myofascial origin 103 Dental papilla (forms dentin and pulp) 6 Dental personnel 193 Dental practice, infection control in 193, 194f Dental pulp 5, 6, 8, 15f, 50 causes of 52, 62 cell-free zone of Weil 9 cell-rich zone 9 classify diseases of 66 connective tissue of 131 diseases of 52, 62, 67 formed 6 odontoblastic zone 8 unique features of 51f Dental sac 6 Dental trauma 401

Dental traumatic injuries 401, 403, 404 management of 401, 404, 413t Dental treatment procedures 56 Dential hypersensitivity 486f Dentin 483f acid etching of 65 bonding agents 66, 293, 485 dysplasia 32 fracture 413 reparative 52f sclerosis 51 sensitivity 483 Dentinal hypersensitivity 482, 484, 491 causes of 484 management of 482, 485, 487, 487t Dentinal tubules 84, 85f to pulp 85f Dentin-chip 307 Dentino enamel junction 482 Dentinogenesis imperfecta 384 Dentin-pulp complex 5 Dentistry, antibiotics in 317 Derivatives of phenol 276 Diamond bur 164 Digital tactile sense 234 Direct pulp capping 405, 441, 459 in traumatized tooth 406f Direct vital pulp therapies 459 Distal angulation 116f Distal root canal of mandibular second molar, infection in 76f Distobuccal canal orifice 218 Doxycycline 319

E Electric pulp tester 122f, 162f Electronic apex locator 167 Elements obturation unit 303f Elliptication, causes of 349 Ellis and Davey’s classification 402 En masse crown fracture 413 Enamel 413, 451 bur 208f cord 7 effects on 391 epithelium inner 7 outer 7 fracture 413 organ (forms enamel) 6

Index

Endo access bur 206f Endoactivator system 278f Endodontic 92 access cavity preparation 199, 200 advances, research-based 498 armamentarium 158 biofilm 94 types of 97f cases 373 diagnosis aids in 98, 161 diagnosis, accurate 129 disease 102, 103t, 418, 424 drugs used in 318f emergencies 323-325, 331 after treatment 335 before treatment 326 classification of 325 midtreatment 323 treatment, Weine’s classification of conditions 325 explorer 167f failure 373 causes of 374, 376 classification of 376 gauge 242f infections 86, 87 control in 192 types of 88f instruments 158, 196 asepsis and sterilization of 192 aspiration of 496 classification of 169 disinfection of 198 interpretation in 116 lesions 415, 418 primary 418 management, nonsurgical 373 materials 158 microbiology 83 microbrushes 277f mishaps 336, 336f, 337 classification of 337 classify 336 management 336 prevention 336 past and present 4t periodontal diseases 416f practice, malpractice in 496 preparation in maxillary premolar 215

retreatment 377, 381, 493 steps of nonsurgical 377 scope of 1, 2f sonics and ultrasonics in 180f spoon excavator 167f, 207f surgery 425, 473 classification of 427 in geriatric patients 473 postoperative sequelae 437f role of 146 surgical 425 armamentarium 429 phase 430 procedure 29 role of isthmi in 29 therapy 130, 138 treatment 140, 150, 150f, 156f, 337, 373, 374, 387, 469, 472 drugs used in 311, 312 failure 497 in geriatric patient 471 inadequate 415 of pediatric patients 450 plan 145, 146f revascularization 505 success of 357 triad 199 use of sonic devices for 178 sonics in (endosonics) 179 ultrasonics (endosonics) 179 Endodontically treated mandibular second molar 343f Endodontically treated teeth 355, 356, 356f changes on 357f physical changes on 356f post systems for 190 restoration of 190, 355 Endodontic-periodontal diseases 415 Endodontic-periodontal lesion 422 classify 416 types of 418, 424 Endodontic-periodontal problems Weine’s classification of 422 types of 423t Endodontist, enigma to 42 Endoflare 258f Endometrics 234 Endovac irrigation system 279f

509

Engine-driven handpieces 177 Engine-driven instruments 177 Enterococcus faecalis 87, 278, 374 Epiphany sealer 293 Erythroblastosis fetalis 384 Extracellular polymeric substances 92 Extracoronal bleaching 396f of vital teeth 391, 392f Extraoral examination 106

F Ferric sulfate pulpotomy 461 Ferrule effect and biologic width 361, 362f Fiberoptic endoscope 161 Fiberoptic light for transillumination test 125f, 162f Fibers 11 Fibroblast growth factor 502 Finger plugger for obturation 187f Finger-held spreader for obturation 186f Fissure carbide bur 164 Flap design, triangular 431f Flap reflection 431, 432 Focal infection 83 mechanism of 131 theory 83, 130 origin of 83 Focal sclerosing osteomyelitis 79 Formaldehyde 276 Formocresol pulpotomy 445 Foundation restoration 371 Fungi 415

G Galilean optical system 159 Gates-Glidden drills 164, 166f, 177 Genera actinomyces 374 Geriatric dentistry 468 Geriatric endodontics 468 scope of 468, 469f Geriatric patient abrasion 471f attrition 471f erosion 471f Giant cell granuloma 118 Gingival irritation 391, 398 Gingival recession 471f

510

Short Textbook of Endodontics

Gingival sulcus 340 Glass bead sterilizers 196f Glass fiber posts 365f Glass fiber-reinforced epoxy resin posts 365 Glass ionomer 458, 461f cement 61, 458 core 368 sealers 293 Glutaraldehyde pulpotomy 460 Glutaraldehyde, advantages of 460 Gram stain technique, classification to 87 Gram-negative anaerobic bacteria 267 Grossman’s classification 375 of endodontic emergencies 326 Grossman’s sealer 290 Gutta-percha 283 canal-warmed 299 carrier-based 285 chemically plasticized cold 299 compaction of 186 cone 419 for newer obturation systems 285 lateral compaction of 295 removal of 187 removal techniques 380 sterilization of 296 stick 285 heated 121f technique solid core carrier-based 306 thermoplasticized injectable 306 thermoplasticized 285, 306 with additives 285 with sealants, solid core 295

Hydrogen peroxide 269, 388 for bleaching 388f, 389 for irrigation 269f Hyperplastic pulpitis, chronic 53, 68 Hypoplastic maxillary teeth 106f

H

L

Halogens 276 Hand-operated instruments 170 Hank’s balanced salt solution 412 Hard tissue surgical access 432 Healing of perforation 340 Hemorrhage from surgical site, management of 433 Hemostasis 406 Hertwig’s epithelial root sheath 77 Holmium:yttrium-aluminium-garnet laser 278 Hydrochloric acid-pumice abrasion 398

Laser Doppler flowmetry 122, 403 in dentistry 123 Laser light emission 489 Laser-assisted root canal preparation technique 261 Lasers classification of 490 in endodontics 488, 491-493 advantages of 494 properties of 488 types of 490 Lingual opposite buccal 116f

I Immunity in endodontics, role of 135 Infection, elimination of 317 Infection, prevention of 317 Inflammatory cells 132 Inflammatory paradental cyst 118 Ingle’s endodontics 476 Intracanal brushes 277 Intracanal medicaments 273 antibiotic containing 276 Intracanal microbial biofilms 94 Intracoronal bleaching 385, 387, 388, 392 of endodontically treated teeth, side effects of 397 of maxillary right central incisor 395f of teeth, side effects of 399f Intraligamentary injection 314, 314f Intraoral examination 106 Intraosseous injection 314, 314f Intrapulpal hemorrhage 385 Intrapulpal injection 315f Irreversible pulpitis 68 in immature permanent tooth 446 with acute apical periodontitis 326 causes 327 signs 326 symptoms 326 Irrigant-related mishaps 333

Lingual shoulder, removal of 210f, 213 Liquid EDTA for removal of smear layer 273f Local anesthesia, armamentarium for 163 Luxation injuries 410 management of 410 Lymphocytes 11 Lysosomal enzymes 133

M Magnifying loupe 206f Mandibular anesthesia 313 Mandibular anterior teeth 219, 396f Mandibular canine 41, 42f, 221 Mandibular central incisor 40, 41f, 219 with two canals 41f and lateral incisor 41f Mandibular first molar 44, 45f, 125f, 224, 224f, 386f, 441f deep occlusal 441f mesial root of 110f periradicular infection in 86f proximal caries approaching pulp 441f pulp, deep occlusal caries in 110f tooth osteitis in relation to 79f postoperative 46f preoperative 46f with canals 225f with endodontic 421f with extensive caries pulp 53f, 74f with five canals 45f with four canals 45f with pulp polyp 143f with radix entomolaris postoperative 46f preoperative 46f with severe periodontal lesion 421 with three canals 45f with three mesial canals postoperative 46f preoperative 46f Mandibular first premolar 42, 43f, 221 with one and two canals 222f Mandibular first primary molar 452, 453f Mandibular lateral incisor 41, 42f, 221 Mandibular left central incisor 394f discolored 394f

Index

Mandibular molar cavity preparation in 225f taurodontism in 32f teeth 223 with deep carious lesion 419f Mandibular posterior teeth, in child 454f Mandibular premolar cavity preparation of 222f teeth 221 Mandibular primary incisors 451, 452f Mandibular second molar 47, 47f, 224 C-shaped canal in 27f tooth osteitis in relation to 79f postoperative 48f with C-shaped canal 47f, 48f, 225f postoperative 48f preoperative 48f with four canals 47f with three canals 47f with two canals 47f Mandibular second premolar 44, 44f, 222 cavity form of 223f tooth 44f with root and root canals postoperative 45f preoperative 45f Mandibular second primary molar 452, 453f, 462f Mandibular teeth, periodontal involvement in 144f Mandibular third molar 47, 48f, 226 cavity preparation in 226f curved canals postoperative 49f preoperative 49f Mast cells 11 Materials bleaching 388 disinfection of root canal 169 isolation of endodontic field 163 obturation 282 postendodontic restoration 190 vital pulp therapy, techniques and 439 Maturogenesis 503 Maxilla, posterior 427 Maxillary and mandibular primary canine 452, 452f Maxillary anesthesia 315

Maxillary anterior region 457f Maxillary anterior teeth 211, 213f, 478 cavity preparation for 213f Maxillary canine 34, 34f, 214 cavity form of 214f postoperative 35f preoperative 35f Maxillary central incisor 32, 33f, 211 cavity form of 213f tooth postoperative 33f preoperative 33f with rubber dam 154f Maxillary first and second premolars postoperative 36f preoperative 36f Maxillary first molar 37, 37f, 218 cavity form of 218f cavity preparation of 219f tooth, MB2 canal in 120f with four canals 38f postoperative 38f preoperative 38f with three canals 38f postoperative 38f preoperative 38f with two palatal canals 38f Maxillary first premolar 35, 35f, 215 cavity form of 216f tooth postoperative 36f preoperative 37f with S-shaped, cases of 227f Maxillary first primary molar 452, 453f Maxillary lateral incisor 33, 34f, 214, 386f cavity form of 214f Maxillary molar 217f cavity preparation for 217f teeth 217 Maxillary posterior region 457f Maxillary premolar teeth 215 cavity preparation for 215 Maxillary primary incisors 451, 452f Maxillary rhinosinusitis 102 Maxillary right central incisor discolored 386f, 394f fracture in endodontically treated 330f internal resorption in 478f

511

Maxillary right lateral incisor infection from 107f tooth, abscess in relation to 76f Maxillary second and third molars, concresence of 31f Maxillary second molar 39, 39f, 219 carious destruction of 356f cavity form of 219f with canal 39f with four canals 40f with three canals 39f, 40 with two canals 39f Maxillary second premolar 36, 36f, 216 cavity form of 217f tooth 37f Maxillary second primary molar 452, 453f Maxillary sinus 427 Maxillary teeth extracoronal bleaching of 396f in child 454f Maxillary third molar 39, 40f, 219 cavity preparation of 219f with three canals 40f Medicated sealers 293 Melton’s classification of C-shaped canals 27 Memory t-cells 132 Mesenchymal cells 11 Mesial and distal boundary 218 Mesial angulation 116f Mesial canal 225f Mesiobuccal canal, second 218 Metal-core obturation 286 Metallic core materials 367 Metronidazole 319 Micro-endodontics, instruments for 161 Mid-root fractures 410 Midtreatment flare-ups 334f Mineral trioxide aggregate 357, 436, 439, 443, 448 pulpotomy 446 Mishaps related to post placement 353 Monocytes and macrophages 475 Motor for rotary instrumentation 184f Mouse-hole effect 201f MTA pulpotomy 461 Mucoperiosteal flap 431 Multi-lens optic system 159 Multirooted teeth, post placement in 366 Myofascial pain vs pulpal pain 103

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Short Textbook of Endodontics

N Necrosed pulp 136f Necrotic immature permanent tooth 503 Necrotic pulp 53f Necrotic root canal 420 Neuropathic pain vs pulpal pain 104 Neuropeptides 133 Neurovascular pain vs pulpal pain 104 Neurovascular structures, damage to 351 Nickel-titanium 299 advantages of 183 alloys, phases of 181 disadvantages of 183 instruments 182, 182t hand and rotary 179 properties of 180f rotary instrument devices for 184 in root canal 183f, 262f systems 184, 257 Nitric oxide 133 Noncollagenous proteins 356 Nonmetallic cores 368 Nonnarcotic analgesics 316 Nonrestorable teeth 144f Nonrigid posts advantages of 364 disadvantages of 364 types of 365 Nonvital pulp therapy 407, 446 for primary teeth 463 for traumatized teeth 409f Nonvital teeth 145, 413 with full prosthetic restorations 360 with partial restorations 360 Normal periradicular tissues 72f Noxious stimuli affecting dental pulp 52

O Obturation techniques 295 Obturation, preparation for 293 Occlusal anatomies 202 Odontalgia, symptoms of 103 Odontoblast 10 Odontoblastic process 483f Odontoclasts and cementoclasts 475 Opioid analgesics 316 Oral foci of infection 131 Orofacial and dental

signs 470 symptoms 470 Orofacial pain 101 of nonodontogenic origin 102 Orthodontic extrusion 423 Osteoblasts 16 Osteoclasts 16 Osteogenic effect 292 Osteomyelitis 118 Ozonated water irrigation 278

P Pain control 312 Palatal roots 428 Palatine artery, anterior 428 Palatine foramen 428 Partial pulpotomy 445 in permanent maxillary central incisor tooth 445f Paste filling materials 287 Pediatric endodontics 450 Periapical abscess 53f, 75f Periapical cyst 78, 78f Periapical granuloma 53f, 77, 77f in maxillary right central incisor tooth 77f Periapical infection 376f in root canal treated mandibular premolar 376f Periodontal disease 417, 418, 424 Periodontal examination 324 Periodontal fibers, types of 17 Periodontal lesion 415, 418 in maxillary molar 420f primary 420 Periodontal ligament 16, 53f Periodontal pocket 421f Periradicular curettage and biopsy 433 Periradicular disease 72 extension of 426 of nonendodontic origin 81 Periradicular surgery 425, 426 armamentarium for 190 treatment planning for 427 Periradicular tissues 5, 14, 16f, 18, 418 causes of 71 classify diseases of 72 diseases of 71 normal 72 of endodontic origin, diseases of 72

Permanent anterior teeth in child, trauma to 454f Phenol and phenol derivatives 276 Phoenix abscess 331 Plasma derived mediators 133 Platelet derived growth factor 502 Plugger finger 302f hand-held 302f types of 302f Polyethylene fiber-reinforced posts 365 Polymerase chain reaction method 91 Polymorphonuclear neutrophils 132 Porphyria 384 Porphyromonas endodontalis 267 Porphyromonas gingivalis 267, 415 Post and core restorations 372 Post related mishaps 353 Post removal system 379f Postbleach sensitivity of teeth 391 Postbleaching inflammation of periodontal ligament 398 Postendodontic restoration 357, 357f, 358, 359, 472 type of 359 Posteruptive causes 385 Postobturation restoration 357 Potassium nitrate 485 Predentin 483f Prevotella intermedia 415 Primary apical periodontitis, pathogenesis of 81 Primary permanent tooth 451f Primary teeth 450, 450f material for 465t materials in pulpectomy of 465t obturation material for 464 obturation techniques in 466 proximal lesions in 455, 457f traumatic injuries to 413 Propionibacterium 87 Protaper endodontic files 256f Pseudomonas 87 Pulp arterial supply of 11 bacterial invasion into 52f caries involving 421f extirpation of 464f functions of 13 gangrenous necrosis of 327 causes 327

Index

diagnosis 327 treatment 328 types 327 infected 85f microorganisms in 84, 84f nerve supply of 14f tissues 12 structural elements of 10 zones of 8f Pulp and periodontal tissues, intercommunication between 414 Pulp and periodontium, interrelationship between diseases of 415 Pulp and periradicular tissues diseases of 62 pathosis of 326 Pulp canal 117 sealer 290 Pulp capping 442, 491 indirect 439, 440, 458 materials 442 steps of direct 442f indirect 441f Pulp chamber 451 components of 19 floor of 19, 20f inspection of 204, 205f morphology of 32 roof of 19, 20f, 218 Pulp degeneration 69 Pulp dressing 405 Pulp exposure 413 crown fracture with 329 crown fracture without 329 in mesially inclined mandibular molar 85f to trauma 85f Pulp fibroblast 10 Pulp hemorrhage 446 Pulp horns 5, 19, 20f Pulp inflammation (pulpitis) 67 Pulp necrosis 53, 71 Pulp necrosis, types of 71 Pulp polyp in deciduous molar 69f permanent mandibular first molar 69f primary second molar 54f

Pulp regeneration 505f Pulp stones 70f Pulp tests 118 Pulp therapies 1, 439 for primary teeth 458 in traumatized teeth 405 performed in children 457 Pulp tissue, pain related to incomplete removal of 331 Pulp to acid etching of dentin 59 reaction of 59f of enamel 59 Pulp to cavity and crown preparation 57 cleansing and sterilization 59 preparation using air abrasion 60 Pulp to dental caries 50 reaction of 51, 55f procedures 54 treatment 56 Pulp to drying of tooth 58 reaction of 59f Pulp to laser procedures 60 Pulp to local anesthetics 56 reaction of 57f Pulp to orthodontic tooth movement 60 reaction of 60f Pulp to periodontal procedures 56 Pulp to periodontium, infection from infected 421f Pulp to polishing of restorations 60 Pulp to specific dental materials 60 Pulp to ultrasonic scaling of teeth, reaction of 57f Pulp to vital bleaching techniques 60 Pulp vitality testing 56 Pulpal blood supply 11f Pulpal diagnosis 455, 491 in children 453, 456f Pulpal diagnostic tests 454 Pulpal disease 417 signs of 421 symptoms of 421 Pulpal infection, cause of 86f Pulpal pain, classification of 102 Pulpal reaction to caries 50 to dental procedures 50

513

Pulpal tissues blood supply of 11, 13f lymph supply of 12 Pulpectomy 463 in primary teeth, steps of 463f Pulpitis, acute irreversible causes 326 diagnosis 326 management 326 signs 326 symptoms 326 Pulpitis, symptomatic irreversible 68 Pulpotomy 491 in primary teeth 459 steps of 462f types of 445 Pulse oximetry 123 Push-pull motion 243f

Q Quaternary ammonium compounds 271

R Radicular cyst 78 Radicular pulp 19, 20f Redox reaction 384 Regenerative dentistry 500 Regenerative endodontic 500, 503, 504, 504f procedures 504 Resin sealers 292 Resin-based obturation system 287, 287f Resin-based sealer-AH plus 292f Resin-based self-etch root canal sealer 293f Resin-modified glass ionomer core 369 Restoration 406 effect on 392 post and core causes of 371f, 372 failure of 371f, 372 Restorative material 189, 436 Restorative resins 61 Restorative treatment 446 Rhinosinusitis, symptoms of 103 Rickert’s sealer 290 Root 117 Root anatomy 366

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Root and root canal system 425 Root apex, anatomy of 26 Root canal 31f, 87f, 117, 351f anatomy of apical portion of 25 apical width of 240f bacteria in infected 87 biomechanical preparation of 231 cavity preparation of 163, 199 cleaning and shaping of 231, 232 components of 20 delivery of sealers in 187 effective shaping of 243 infected 86 instruments of 186 ledge formation in 347f microbes from 89 microbial flora of 84 microbiology of infected 89f obturation of 186, 280, 281, 493 shaping of 464f underfilling of 335 Root canal anatomy of individual teeth, primary 451 Root canal disinfectant 265 Root canal filling material 283 classification of 283 Root canal infections 87 Root canal instruments 170, 171f Root canal irrigants 248, 265, 267 Root canal of primary teeth 464 Root canal opening 145, 323 Root canal orifices 209 exploration of all 204 flaring and exploring 204f Root canal preparation 233, 263, 491 crown-down technique of 248, 250 devices for 169 hand instruments for 172 instruments for 169 of apical third and body of canal 247f rotary instrumentation 254 sonics 261 step down technique of 250 step-back method of 245 steps of crown-down technique of 249 techniques of 244, 245, 254 terminology for 241 ultrasonics 261 Root canal sealers 282, 288, 288f, 289 in obturation 289 paraformaldehyde-based 497

Root canal system 19 activation of irrigants in 277f anatomic complexities in 26 anatomic components of 19 anatomy of 21, 29 classification of 22 components of 20f disinfection of 264, 265, 491 in geriatric patient 470f in root, types of 21 in young adult tooth 470f internal anatomy of 19 morphology of 32, 34, 35 obturation of 280, 472 of individual teeth 32 solutions in 276 Weine’s classification of 23f with increasing age 21f Root canal treatment 1, 139, 141, 419 Root end cavity preparation 435 advantages of 435 Root end beveling of 434f conditioning 435 development 448f management 434 resection 434 Root fracture 117, 118, 329, 354, 372, 409, 413 crown 409 of palatal root of maxillary second premolar tooth 120f Root perforations 415 Root resection 422 Root resorption 117 classification of 475 differences between external and internal 480 external 79, 80f, 117, 476, 476f cervical 397 internal 117, 478, 478f mechanism of 475 types of external 476 internal 479 Root-end resection, angle of 434 Roots and root canals, anatomy of 227 Roots of maxillary molar, apical third of 31f Rotary endodontic file, components of 181f

Rotary instrumentation 254 Roth’s sealer 290 Rubber dam clamps 152f forceps 153, 153f frame 152, 152f in endodontic treatment in mandibular first molar 154f material 151 placement 153 punch 153, 153f sheet 151, 152f components of 151

S Schilder technique 299 Sealapex root canal sealer 291f Sealer placed in root canal 288 Sickel cell anemia 384 Silicone-based sealers 293 Silver amalgam 61, 461 restorations 392 Silver point 287f obturation with 295f, 497 removal of 189, 379 Smear layer 272f in endodontics, management of 272 removal of 271 Sodium hypochlorite 267, 268, 269f, 356, 381, 446 accidents 268, 350 efficacy of 268 for irrigation 267f Sodium perborate 388 Sound tooth structure remainingnonrestorable tooth 144f Stainless steel and nickel-titanium instruments 181t properties of 181 Stem cells 501 types of 501 Step-back technique v/s crown-down technique 252, 252t Streptococcus faecalis 87 Strontium chloride 485 Stropko irrigator 266 Sulfur granules 95 Supernumerary roots 32 Superoxidized water 276

Index

T Teeth accessibility of 142 anterior 359 bleaching of 383, 494 classify traumatized 402 cracked 64 crowded 228 crown of 109, 116 development of 6 discolored nonvital 143f hypersensitive 482 injury to 62 internal resorption in 120f laminates for discolored 400 management of 412 discolored 382, 383, 400 mobility of 108f normal 85f opening in wrong 337 perpendicular to 116f pink 144f, 478 posterior 359 preparation of individual 211 regressive changes in 469 root of 109 permanent 474 primary 474 rotated 228 structurally sound anterior 359 traumatic injury to (acute trauma) 63 treatment of traumatized 404, 404f veneer for discolored 400 vitality of 471 Teeth, in elderly 469, 470t Teeth, in pediatric patients 450 Teeth to tetracycline, discoloration of 384f Teeth to wasting diseases, yellowish discoloration of 386f Teeth with calcifications in pulp chamber 226 in root canals 226

Teeth with curved canals 227 Teeth with minimal coronal tooth structure 228 Temporary filling 205f Temporary restorations 189 Test cavity 126 Tetracycline isomer, mixture of 272 Thalassemia 384 Thermafil obturator 307f Thermocatalytic bleaching 397 Tissue emphysema 334 cause 334 management 335 prevention 335 signs 334 symptoms 334 Tissue engineering 501 triad 501f Tissue regeneration 503 Tooth with dilaceration 120f with internal resorption 479f with pathology to radicular cyst 79f Tooth avulsion 330, 411 management 330 Tooth crown of caries 116 Tooth development, stages of 6 Tooth discoloration 384 causes of 382 etiology of 387f management 384 Tooth in arch, position of 358 Tooth infractions 64 Tooth length, measurement of 236f Tooth pulp chamber, crown of 117 Tooth removal, overzealous 338 Tooth resorption 474, 475 pathologic 474 types of 475, 476 pathologic 481f Tooth slooth 124f, 162 contact with cusp tips 124f Tooth structure 446 amount of remaining 358, 365 removal of unsupported 203, 203f

515

Tooth treatment, incorrect 496 Transillumination test 125f Trapezoidal flap design 432f Treponema denticola 87, 415 Treponema maltophilum 415 Tubli-seal root canal sealer 291f

U Ultrasonic cleaner 197f Ultrasonic instrument 178 Ultraviolet photo-oxidation 397 Underextended obturation 352f Underfilled obturation 352f Urethane methacrylate sealers 293

V Vasoactive amines 133 Vertucci’s classification 23 Viscous chelator 273 Vital pulp therapy 405, 439, 440f, 446 for traumatized teeth 407f Vital pulps with normal periapical tissue 472

W Wach’s cement 291 Walking bleach result 393 technique 392 Weeping canals 275

Y Young permanent teeth 451, 451f

Z Zinc oxide 443 eugenol 60, 441, 461f, 464 Zinc oxide-containing sealers 289 Zinc phosphate cement 61 Zones of reaction 136t