Best Practices in Endodontics: A Desk Reference [Illustrated] 9780867156775, 0867156775

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Best Practices in

ENOODONTICS A Desk Reference Edited by

Richard S. Schwartz, DDS Private Practice Limited to Endodontics San Antonio, Texas

Venkat Canakapalli, BDS, MDS Private Practice Limited to Endodontics Tauranga, New Zealand

Anthony

m

Illustrations by L. Horalek, DDS, MS

Quintessence Publishing Co, Inc

Chicago, Berlin, Tokyo, London, Paris, Milan, Barcelona, Istanbul book/ Moscow, New Delhi, Prague, Sao Paulo, Seoul, and Warsaw

Dedication , who stood , To my parents, Arnie and Carol Schwartz, who supported and encouraged me. To my wife Jeannette can. beside me all these years . And to my daughter, Marni, who has enriched my life as only a child

— RS me to To my parents, teachers, and friends, and to the extraordinary clinicians on the TDO forum who inspired . dreams my follow do this book . And to my wife, Mithuna, who encourages and supports me to VC

—

I dedicate these illustrations to Nebraskans Wilma and Robert Fulk , without whom my entry into private practice would not have been possible; Wade Jensen, my favorite cousin, who has always believed in me; and Gary Carr; the founder of Pacific Endodontic Research Foundation ( PERF ) and The Digital Office (TDO ), who created the environment for hundreds of us to become outstanding endodontists. — TH

Library of Congress Cataloging-in-Publication Data Best practices in endodontics : a desk reference / edited by Richard S. Schwartz and Venkat Canakapalli ; Illustrations by Anthony L. Horalek. p. ; cm. Includes bibliographical references and index. ISBN 978-0-86715- 677-5 I. Schwartz, Richard S., editor. II. Canakapalli, Venkat, editor. [ DNLM: 1. Endodontics--methods--Handbooks. 2. Dental Pulp Diseases-therapy-Handbooks. 3. Root Canal Therapy-Handbooks. WU 49 ]

RK351 617.6'342~dc23

2014043663

quMe//ence book/

© 2015 Quintessence Publishing Co, Inc Quintessence Publishing Co, Inc 4350 Chandler Drive

Hanover Park, IL 60133 www.quintpub.com

5 4 3 2 1

All rights reserved. This book or any part thereof may not be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, or otherwise, without prior written permission of the publisher . Editor: Leah Huffman Design: Ted Pereda Production: Angelina Sanchez

Printed in the USA

Contents Dedication iv Contributors V / /7 Preface ix Introduction X

PART I The Dental Operating Microscope 1 1 Operatory Design and Ergonomics for Microscopic Endodontics 3 Gary B. Carr

2 Setting Up Your Dental Operating Microscope for Photography 77 Scott K. Bentkover

3 Setting Up Your Dental Operating Microscope for Videography Scott K. Bentkover

4 Photodocumentation for Endodontics Jeffrey B. Pafford and Keith G. Kanter

47

5 Training an Assistant to Work Under an Operating Microscope 46 Michael Trudeau

PART II Cone Beam Computed Tomography and Endodontics 6 Incorporating CBCT Imaging into Endodontics 55

53

7 Clinical Applications of CBCT Imaging in Endodontics

77

Gary B . Carr, John Khademi, and Richard Schwartz

Sashi Nallapati

PART III Nonsurgical Endodontic Procedures

87

8 Access Cavity Preparations 89 Pushpak Narayana

9 Working Length

704

Mike Gordon

10 Preparation of the Root Canal System

709

Steven Baerg and Eric Herbranson

11 Clinical Management of Calcified Teeth

720

Sashi Nallapati

12 Clinical Management of Severely Curved Canals John E. Levin

13 Obturating with Gutta-Percha Master Cones

730

736

Scott A. Martin

14 Obturation with High-Temperature, Thermoplasticized, Injectable Gutta- Percha 747 Robert Corr

29

Contents 15 Clinical Management of C-Shaped Canal Configurations Jason C. Joe

148

PART IV Retreatment 157 16 Bypassing Ledges, Separated Instruments, and Other Obstructions 159 Fred S. Tsutsui and Robert H . Sharp 17 Removing Metal and Fiber Posts 167 Marga Ree

18 Removing Silver Points and Gutta-Percha Carriers Scott T. Weed

175

19 Retreatment of Teeth Containing " Russian Red " Endodontic Paste Ivan N . Vyuchnov

20 Repair of Iatrogenic Perforations

191

Robert Corr

PART V Restorative Considerations

199

21 Evaluating Restorability Prior to Treatment

201

Venkat Canakapalli

22 The Pre-endodontic Buildup

212

Rahim Karmali

23 The Customized Resin Matrix

218

Michael Trudeau

24 Restorative Procedures with Posts 227 Richard Schwartz

25 Esthetic Restoration of Access Cavities Ron Fransman

234

26 Bonding to Ceramic Materials 238 Richard Schwartz

PART VI Resorption 243 231 Diagnosis and Treatment Planning for Resorption Richard Schwartz

245

28 Nonsurgical Treatment of Invasive Cervical Resorption Richard Schwartz

29 Surgical Treatment of Invasive Cervical Resorption Richard Schwartz

253

258

30 Treatment of Internal Resorption and External Inflammato ry Resorption 262 Richard Schwartz

183

31 Flapless Decoronation for Teeth with Replacement Resorption 268 Jared Buck

PART VII Trauma Management 273 32 Immediate Surgical Extrusion 275 Mary M . Chien and Rajiv G. Patel 33 Orthodontic Extrusion 281 Venkat Canakapalli and Mithuna Vasudevan

34 Clinical Management of Horizontal Fractures 286 Richard Schwartz and Marga Ree

35 Clinical Management of Incisors with Complex Fractures Michael Trudeau

PART VIII Other Topics 299 36 Clinical Management of Teeth with Open Apices with the Apical Barrier Technique 301 Marga Ree

37 Vital Pulp Therapy in Immature Teeth

310

Marga Ree

38 Decompression 316 Scott A. Martin

39 Suturing Under the Microscope

320

Ivan N . Vyuchnov

40 Keys to Effective Communication 331 Mitchell H . Davich and Marc Balson

41 Quality Intraoral Radiography for Endodontics 337 Andrew L. Shur

Index 343

292

Contributors Steven Baerg , DMD Private Practice Limited to Endodontics Gig Harbor, Washington

Marc Balson,

Mike Gordon, BDS, MDS ( Endo), MRACDS (Endo ) Private Practice Limited to

Endodontics

Eric Herbranson, DDS, MS Private Practice Limited to Endodontics San Leandro, California

Private Practice Limited to

DDS

Clinical Assistant Professor Director of Microscopic Endodontics College of Dentistry University of Illinois at Chicago Chicago, Illinois

Jason C. Joe,

Private Practice Limited to

Keith G. Kanter,

DDS

Private Practice Limited to Endodontics Honolulu, Hawaii

Endodontics Orlando, Florida

Endodontics Carson City, Nevada

Venkat Canakapalli,

MDS

Private Practice Limited to

Rahim Karmali,

DDS

Private Practice Limited to

Tauranga, New Zealand DDS

Private Practice Limited to

Endodontics San Diego, California

Endodontics Durango, Colorado

Private Practice Limited to

Endodontics Morristown, New Jersey

Ron Fransman, DDS Private Practice Limited to Endodontics Amsterdam, The Netherlands

Endodontics

John E. Levin, DDS, MS Adjunct Clinical Professor Department of Endodontics Saint Louis University Center for Advanced Dental Education St Louis, Missouri

Private Practice Limited to

Endodontics Suffolk, Virginia

Fred S. Tsutsui,

DMD

Private Practice Limited to

Endodontics

Mithuna Vasudevan ,

MDS

Private Practice Limited to

Orthodontics Tauranga , New Zealand

Endodontics Moscow, Russia

Endodontics Kingston, Jamaica MDS

Private Practice Limited to Endodontics

Lady Lake, Florida

DDS

Private Practice Limited to

Ivan N. Vyuchnov, DDS, MSC Private Practice Limited to

BDS

Pushpak Narayana ,

Michael Trudeau,

Torrance, California

Endodontics Lafayette, Louisiana

Sashi Nallapati,

Endodontics Portland, Maine

Private Practice Limited to Microendodontics Hacienda Heights, California

Mitchell Davich, DMD

Private Practice Limited to

Andrew L. Shur, DDS Private Practice Limited to

Scott A. Martin, DDS Private Practice Limited to Microendodontics Duvall, Washington

Endodontics Colorado Springs, Colorado

Endodontics San Antonio, Texas

John Khademi, DDS, MS

Private Practice Limited to

Private Practice Limited to

DDS

Private Practice Limited to

Sacramento, California

Mary M. Chien, BDS, MS Clinical Assistant Professor Graduate Endodontic Department Ostrow School of Dentistry University of Southern California Los Angeles, California

Robert Corr, DDS, MS

Marga Ree, DDS, MSC Private Practice Limited to Endodontics Purmerend, The Netherlands

Endodontics Denver, Colorado

Private Practice Limited to

Endodontics

Endodontics Carrollton, Texas

Robert H. Sharp, DDS

DDS

Private Practice Limited to

BDS, DDS

Richard Schwartz, DDS

Private Practice Limited to

Endodontics Evanston, Illinois

Gary B. Carr,

Endodontics Decatur, Georgia

Rajiv G. Patel,

Livingston, New Jersey

Jared Buck,

Private Practice Limited to

Endodontics Hamilton, New Zealand

DDS

Private Practice Limited to

Scott K. Bentkover,

Jeffrey B. Pafford, DMD, MS

Scott T. Weed, DDS Private Practice Limited to Endodontics Reno, Nevada

Preface Most accomplished clinicians credit much of their suc cess to their mentors. All of the contributors to this book have benefited from and acted as mentors. Over the past 15 years, the contributors have participated in an online discussion group as part of a virtual community of endodontists from around the world. All of us post cases for discussion, review research, collectively solve clinical problems, and learn from our long-term successes and failures. One day one of the members suggested that it would be nice if we could catalog and share some of this knowledge with a wider audience That is the purpose of this book. This book is " microscope centric" in the sense that all the contributors use a dental operating microscope for every patient. The procedures described in this book are best performed (and some can only be performed) under a dental operating microscope. Although endodontics can be performed without a microscope, a clinician's level of care improves as microscope skills are acquired. The first five chapters are devoted to the microscope itself, including operatory design, photographic and video documentation of treatment, and how to do clinical procedures in the most efficient and ergonomic manner for the doctor and assistant. This material will be very useful to clinicians who are designing or remodeling an office and who want to document their work. It will be useful for both beginners and experienced clinicians and

derway. It will contain material collected and organized in a manner that is not available anywhere else in the dental literature. It will be heavily referenced and will require several readings and " study " to gain an understanding of the benefits and pitfalls of CBCT and many of the common errors in interpretation. The importance of recalls is emphasized throughout the book. Without long-term recalls, we are totally in the dark as to whether our treatments are successful. When recalls are included in the endodontic literature, they are rarely more than 2 or 3 years ' follow-up. Recalls only start to become relevant in the 5- to 10-year time frame We currently practice in the " implant era," where relevant time frames have stretched out to 15- and 20-year mea sures of success and failure. A number of chapters are therefore devoted to restorative procedures, because in many cases, the restorative status of the tooth before and after endodontic treatment is the most important

.

.

factor that determines longevity. This book is designed to be a clinician's guide in daily practice and is not a substitute for standard endodontic textbooks. It is not intended to be "scholarly " or " evidence based," although some of the chapters are well referenced. Many of the chapters are devoted to a single procedure or topic and are written as how -to guides. Specific armamentaria and step-by -step instructions are included, and documented cases are used to illustrate specific principles. Chapters include practical information and " pearls " on a wide range of everyday clinical problems and scenarios. These chapters are intended to provide clinical guidance to clinicians performing unfamiliar procedures or wanting to learn alternatives to their usual approach. It is a book written by clinicians for clinicians, at a specialist level, but it is intended for anyone who wants to provide endodontic care at a high level.

especially graduating residents. This book is also " CBCT centric." CBCT (cone beam computed tomography) is an integral part of the daily practice of all of the contributors. Two chapters are devoted to utilization of CBCT in endodontics, and it is integrated into the clinical chapters throughout the book. Several additional chapters on CBCT were originally planned for this book, but the amount of material grew to the point that a separate book is currently un-

Richard S. Schwartz, DDS Venkat Canakapalli, MDS

0

Introduction The contributors to this book come from various backgrounds, geographic locations, and clinical areas of ex pertise. What they all share, however, is a specific vision of what the specialty of endodontics represents today and, more specifically, what an endodontist represents. In attempting to set the highest possible clinical standard for our specialty, we call upon all endodontists to join us in a re-examination of our core principles and a rededication to the vision that began this specialty more than 60 years ago.

The first part of this re-examination addresses the question: " What is endodontics?" The American Association of Endodontists answers this question with the following: Endodontics is the branch of dentistry that is concerned with the morphology, physiology, and pathology of the 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.1

This answer shapes and constrains the traditional view of clinicians and academics who consider the primary purpose of endodontic therapy to be the prevention or elimination of apical periodontitis "by means of cleaning, shaping, disinfecting, and filling the root canal system." 2 This disease-centric orientation dominates the priorities and directs the focus of our scientific research and scientific journals. It permeates our critical evaluation of clinical procedures and the procedural recommendations found in many textbooks for the broader dental audience.3-15 It concludes that addressing the endodontic "triad" is the basis for successful endodontic treatment and forms the foundational basis of our specialty.12'14-16 The contributors to this book view the purpose and end goal of endodontic treatmentfrom a different perspective. We see endodontics as a branch of restorative dentistry whose primary purpose is the preservation of the natural dentition over the length of a patient's life. Such a difference in vision is not merely pedantic in nature; it affects virtually every facet in the study of endodontics. Specifically, it affects how we make clinical decisions and how we interpret and measure our outcomes, and it establishes our procedural goals and recommended best practices. The assumed concordance of the goals of tooth preservation and disease elimination—assumptions that permeate our specialty—we view with increasing skepticism, and we suspect that these goals often operate at crosspurposes. Endodontics has fixated on clinical treatment objectives and end points directed toward removal of the pulpal remnants and bacteria that are believed to be the etiologic agents of endodontic disease. Thus, elimination of the causative agents of disease has become the objec-

five of endodontic treatment.3 This focus often comes at the cost of competing considerations, which are at least as important for long-term tooth preservation, including structural and restorative considerations. The key aspect of this discussion starts with a new answer to the question " What is a successful outcome?" Tra ditionally, endodontic outcome measures were diseasecentric, with disease being defined based on histologic critera.17-19 Because we generally do not have histology available as an outcome measure, we rely on radiographic findings to determine the presence of apical periodontitis,9'17 and the radiographic outcome is considered a primary measure of "success," 20 Strindberg21 developed the initial definition of success in 1956, which included very stringent criteria, including radiographic reestablishment of a well-defined periodontal ligament. With the introduction of CBCT into endodontics, a new Periapical Index (PAI) based on CBCT was developed,22 which has continued this discussion.23-26 These erroneous outcome measures have created problems for our specialty for decades that will not be improved by a CBCT-PAI. CBCT allows clinicians to identify even more " lesions " and "pathology " associated with teeth that have been free of clinical signs and symptoms for decades. Compounding this problem is that the majority of endodontic outcomes analysis counts death of the tooth as a good outcome because extracted teeth are excluded from the analysis. So ingrained in the clinician's psyche is this radiographic measure of outcome that study designs that violate basic CONSORT guidelines are common, with little awareness of how skewed the analysis becomes. Therefore, we are not only studying the wrong outcome measure, but we are studying it incorrectly. For these and other reasons, we draw a distinction between process-centered outcomes, clinician-/ diseasecentered outcomes, and patient-centered outcomes:

•Process-centered

outcomes are the results of procedures the clinician performs. These include factors like the target parameters and end results of the cleaning, shaping, and obturation procedures and the radiographic appearance of the completed case. In many cases, process-centered outcomes have no relationship to clinician-/disease - centered outcomes or patient centered outcomes, yet they make up the vast majority of articles in the endodontic literature. •ClinicianVdisease-centered outcomes are signs and findings that the clinician measures or observes as proximal evidence of treatment efficacy, or lack thereof. First among these is radiographic evidence of resolution of apical periodontitis (often inappropriately described as " healing of the lesion"). This outcome measure may or

may not be related to the selected process- centered outcomes or to patient-centered outcomes. are outcomes that are rel•Patient-centered outcomes 27 evant to patients. They are outcomes that patients notice and care about, such as survival or loss of the tooth, normal function, symptoms such as pain or swelling, or health-related quality of life.27 A test for patientcenteredness is the following question: "Were it to be the only thing that changed, would patients be willing to undergo a treatment with associated risk, cost, or inconvenience?"

References 1. American Association of Endodontists. Specialty of Endodontics. http://www.aae.org/about-aae/specialty-of-endodontics. aspx. Accessed 28 January 2015. 2. American Association of Endodontists. Myths about Root Canals and Root Canal Pain, http://www.aae.org/patients/ treatments-and- procedures / root- canals/myths-about -root canals-and-root -canal-pain.aspx. Accessed 29 January 2015. 3. Paredes-Vieyra J, Enriquez F. Success rate of single- versus

canal treatment of teeth with apical periodontitis: A randomized controlled trial. J Endod 2012;38:1164— 1169. 4. Sedgley C, Nagel A, Hall D, Applegate B. Influence of irrigant needle depth in removing bioluminescent bacteria inoculated into instrumented root canals using real-time imaging in vitro. Int Endod J 2005;38:97-104. 5. Silva LA, Novaes AB Jr, de Oliveira RR, Nelson-Filho P, Santamaria M Jr, Silva RA. Antimicrobial photodynamic therapy for the treatment of teeth with apical periodontitis: A histopathological evaluation. J Endod 2012;38:360-366. 6. West J. Endodontic predictability: " What matters? " Dent Today 2013;32:108,110-113. 7. Siqueira JF Jr, Rogas IN. Clinical implications and microbiology of bacterial persistence after treatment procedures. J Endod 2008;34:1291-1301. 8. Fleming C, Litaker MS, Alley LW, Eleazer PD. Comparison of classic endodontic techniques versus contemporary techniques on endodontic treatment success. J Endod 2012;36:414-418. 9. Molander A, Warfvinge J, Reit C, Kvist T. Clinical and radiographic evaluation of one- and two-visit endodontic treatment of asymptomatic necrotic teeth with apical periodontitis: A randomized clinical trial. J Endod 2007;33:1145-1148. 10. Trope M, Bergenholtz G. Microbiological basis for endodontic treatment: Can a maximal outcome be achieved in one visit? Endod Topics 2002;1 (1) 40-53. 11. McGurkin-Smith R, Trope M, Caplan D, Sigurdsson A. Reduction of intracanal bacteria using GT rotary instrumentation, 5.25% NaOCI, EDTA, and Ca(OH) 2. J Endod 2005;31:359363. 12. American Association of Endodontists. Access Opening and Canal Location. Colleagues for Excellence, Spring 2010. 13. American Association of Endodontists. Root Canal Irrigants and Disinfectants. Colleagues for Excellence, Winter 2011. 14. Castellucci A. Endodontics, vol 1. Florence: II Tridente, 2009. 15. Ingle J I, Bakland LK. Endodontics, ed 5. Hamilton, ON: BC Decker, 2002. 16. Cohen S, Hargreaves K. Pathways of the Pulp, ed 9. St Louis: Mosby, 2006. 17. Nair P, Sjogren U, Figdor D, Sudqvist G. Persistent periapical radiolucencies of root- filled human teeth, failed endodontic treatments, and periapical scars. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1999;87:617-627. 18. Nair PN. On the causes of persistent apical periodontitis: A review. Int Endod J 2006;39:249-281. two-visit root

outcomes and clinician-/diseasecentered outcomes are important, but only as they serve to help us improve or predict patient-centered outcomes.28

Process-centered

The perspectives expressed throughout this book emphasize patient-centered outcomes. Our historical focus on process-centered outcomes and clinician-/ disease-centered outcomes has misled us into studying the wrong outcome measures over an inappropriately short time frame. Much of this problem traces back to how we have defined endodontics and endodontic disease from the beginning. When reading these chapters, please keep in mind that the primary goal of endodontic treatment is the long-term preservation of the dentition, not the lack of evidence of apical periodontitis. This lack of evidence of apical periodontitis, which is all a radiograph can show, is often mistaken for total elimination of disease (or evidence of health), based on the processes we infer are required to eliminate the disease. Obviously, all of us would wish to totally eliminate disease if we could; however, this is rarely possible in chronic disease states. Trying to achieve this goal by aggressive coronal and radicular preparations results in weakening of the tooth or, in some cases, premature loss of the tooth, with no real evidence that it results in a better "Strindberg result." We must look at the larger picture and develop diagnostic and treatment protocols that better serve the goal of long-term tooth retention.

Gary B. Carr, DDS

John A. Khademi, DDS, MS Richard S. Schwartz, DDS

0

24. Wu M, Wesselink Pf Shemesh H. New terms for categorizing the outcome of root canal treatment. Int Endod J 2011;44:1079-1080. 25. Patel S, Mannocci F, Shemesh H, Wu MK, Wesselink L, Lambrechts P. Radiographs and CBCT Time for a reassessment ? Int Endod J 2011;44:887-888. 26. Liang Y, Li G, Wesselink PR, Wu MK. Endodontic outcome

19. Paula -Silva FW, Wu MK, Leonardo MR, da Silva LA, Wesselink PR. Accuracy of periapical radiography and cone-beam computed tomography scans in diagnosing apical periodontitis using histopathological findings as a gold standard. J Endod 2009;35:1009-1012. 20. Saini H, Tewari S, Sangwan P, Duhan J, Gupta A. Effect of different apical preparation sizes on outcome of primary endodontic treatment: A randomized controlled trial. J Endod 2012;38:1309-1315. 21. Strindberg L. The dependence of the results of pulp therapy on certain factors. Acta Odontol Scand 1956;14(suppl 21): 1-175. 22. Estrela C, Bueno MR, Azevedo BC, Azevedo JR, Pecora JD. A new periapical index based on cone beam computed tomography. J Endod 2008;34:1325-1331. 23. Peters C, Peters O. Cone beam computed tomography and other imaging techniques in the determination of periapical healing. Endod Topics 2012;26:57-75.

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predictors identified with periapical radiographs and conebeam computed tomography scans. J Endod 2011;37:326-

331. 27. PCORI Methodology Committee. The PCORI Methodology Report November 2013. http://www.pcori.Org/assets/2013/11/ PCORI-Methodology-Report.pdf. Accessed 29 January 2015. 28. Guyatt G, Rennie D, Meade MO, Cook DJ. Users ' Guides to the Medical Literature: A Manual for Evidence -Based Clinical Practice, ed 2. New York:McGraw-Hill Professional, 2008.

ED

PART I

The Dental Operating Microscope

CHAPTER

I

Gary B. Carr, DDS

Operatory Design and Ergonomics for Microscopic

The Role of the Microscope in Modern Endodontic Practice Before considering ergonomics and operatory design, we should clarify our ultimate objective. Briefly, in an ideal ergonomic practice, all procedures are performed under the microscope, even those that do not require a microscope to be performed competently. For example, screening a patient for oral cancer, administering anesthesia, and checking occlusion are procedures that are not typically thought to need magnification. The important question is not whether the microscope is required to perform a task but rather, in performing one set of tasks with the microscope and another set without it, is ergonomic efficiency negatively affected? The answer to that question is almost always "yes." Working in an environment where the microscope is constantly being moved into and out of the field is extremely inefficient and tends to be very distracting for the doctor, the assistant, and even the patient. Such a practice model fragments continuity of care, reduces focus on the task at hand, and often requires the use of Classes III, IV, and V motions (described later), thus dramatically decreasing both health and efficiency. For these reasons, we have come to understand that if the clinician can learn to incorporate ergonomic techniques and perform all procedures under the microscope whether magnification is needed or not—then efficiency, focused concentration, competence, teamwork skills, and job satisfaction are all enhanced.

—

0

!

1

Operatory Design and Ergonomics for Microscopic Endodontics

Box 1-1

Benefits of implementing ergonomic science into operatory design

•Stress reduction •Reduction in repetitive motion injuries •Healthy posture •Elimination of burnout •Enhancement of clinical excellence

•Healthy practice culture •Elimination of disability •Efficient office design

•Time-motion efficiency

•Reduction of fatigue

•Maintenance of optimal mental outlook

Understanding Basic Ergonomic Principles Ergonomics is the science of maximizing human performance and well-being and involves a study of both human excellence and health. Proper ergonomic design is necessary to prevent repetitive strain injuries and other musculoskeletal disorders, which can develop over time and lead to long-term disability. Box 1-1 summarizes the benefits of implementing ergonomic science into operatory design.

Ergonomic classes of motion Ergonomic science classifies the kinds of motions required to perform a specific task. Generally, a task that can be completed using a single class of motion is more efficient than the same task performed with multiple classes of motion. For example, passing a mirror using just a Class I motion is far more efficient than using a combination of Classes I, II, III, IV, and V motions. Table 1-1 summarizes the classifications of motion, and there are several videos available on YouTube demonstrating how they impact efficiency and performance during endodontic procedures.1 In endodontics, proper ergonomic design criteria are based on the goal of reducing Classes III, IV, and V motions while producing a healthy and injury-free environment where Class I and Class II motions predominate. With proper training, discipline, and teamwork, it is possible to perform nearly all endodontic procedures under a microscope using only Class I and Class II motions, with only an occasional need for Class III motion. Once this skill is mastered, the clinician will reap the benefits of increased productivity, heightened competence, stress reduction, postural balance, and an enhanced practice culture of focused teamwork. Executing efficient ergonomics is a habit that is mastered through repetitive training. While bad habits are difficult to break once formed, good habits and proper technique can become part of routine practice in a short period of time. A clinician or an assistant can learn the required skills if there is effortful practice and a work environment conducive to learning and mastering a new skill set.

•Safety •Performance consistency •Retention of talented staff

Key design parameters of ergonomic operatory design Operatory design and ergonomic technique go hand in hand. Even if the clinical team is practiced and wellversed in proper ergonomic skills, it is almost impossible to execute good ergonomic practice if the operatory does not reflect proper ergonomic design. The circle of influence, a key principle in both operatory and front office design, posits that all instruments (ief armamentaria, recordkeeping devices, viewing monitors) involved in the delivery of care should require nothing more than a Class III motion for both the doctor and the assistant (Fig 1-1). Employing such a principle places significant constraints on operatory and front office designs. Additionally, the operatory should be designed with sight angles so that there is little need to turn one's head to view monitors, use keyboards, or procure accessory devices. There are nine key elements that are required to realize good ergonomic operatory design (Table 1-2). The following sections describe each one briefly and discuss its role in ergonomics.

Microscope parameters In order for the clinician to perform all dental procedures under a microscope, the lowest magnification should be not much over 2.2 X . If the magnification is higher (ie, 3.5 X or even 2.7 X ), it is difficult to complete certain procedures such as giving anesthesia, placing bands, prepping teeth, or performing an oral cancer examination, among others. If the practitioner adopts a model of practice where the scope is moved in and out of the operating field for different procedures and there is a continual changing of working positions, the result will be frustration and inefficiency and, ultimately, disappointment with microscope use. Lower productivity can be avoided if the microscope's lowest magnification is 2.2 X . The ideal practice model is to bring the microscope into position at the start of a patient visit and never change that position until the procedure is completed.2 We recommend a six-step microscope or a zoom microscope that has the capability of lowpower magnification of 2.2 X (Fig 1-2). At this magnifi-

Understanding Basic Ergonomic Principles

Table 1-1

Classifications of motion

I

Class I

Moving only the fingers

Class II

Movement from the wrist

Class III

Movement from the elbow

Class IV

Movement from the shoulder

Class V

Movement from the waist

Fig 1-1 (a ) Aerial view of the circle of influence design principle. View of the doctor' s (yellow circle) and the assistant 's (red circle) respective circles of influence, (b ) The circle of influence design principle states that all required instruments and devices are within easy reach.

Table 1- 2

Nine elements required for good ergonomic operatory design

Element

Requirement

Microscope parameters

Six-step or zoom with lowest magnification down to 2.2 X

Patient chair and headrest

Must be freely movable (rotation) and without a headrest

Doctor and assistant stools

Dual adjustable (height and angle) armrests, adjustable lumbar

Microscope mounting

Wall, ceiling, floor mounts

Assistant/co-observation scope

Adjustable, dual-axis (not single-axis) co-observation tube with inclinable binoculars

Doctor cart or delivery system

Freely movable with internal water supply and compressor

Back wall design

Self-contained assistant's platform and storage as well as suction

Assistant monitor

Viewable from the assistant's working position

Doctor monitor

Viewable from both the doctor's and the assistant's working position

support

s

1

Operatory Design and Ergonomics for Microscopic Endodontics

Fig 1- 2 A six-step microscope with beam split- Fig 1-3 The circle of light shows the viewing Fig 1 -4 View seen at 2.2 x with a six-step ter, assistant ' s scope, and camera. Global microscope. area with a six-step microscope.

Fig 1- 5 (a ) Pillow placement replacing the chair headrest, (b ) Pillow placement to support the neck.

cation, the clinician can see from the floor of the nose to the bottom of the chin on most patients and is able to perform an oral examination, oral cancer screening, and occlusal examination provided he or she is able to move the patient chair effortlessly. Figures 1-3 and 1-4 demonstrate the circle of light range and the view seen at 2.2 X . Clinicians using three-, four-, or five-step microscopes experience far more difficulty and typically revert back to a practice model where the microscope is used only for certain procedures, thereby guaranteeing inefficiency.

lessly requires a patient chair that “ floats" freely, so the microscope itself rarely needs to be touched other than to change magnifications or make small adjustments in focus. What may not be evident to all clinicians is that nearly all endodontic procedures have a natural procedural flow to them, and the skillfulness required for these procedures is affected adversely by even minute interruptions or fragmentation. Preventing this fragmentation by moving the chair instead of the microscope eliminates such interruptions and allows one to work continuously with total focus on the procedure itself and not on the tool being used to perform the procedure. A second factor concerning the patient chair is the size and location of the chair headrest. The headrest is almost always a problem for the endodontist performing all procedures under the microscope. With most headrests, the patient 's head cannot be positioned close to the doctor's lap, and the doctor will be required to bend forward at the waist ( a Class V motion), creating back, neck, and shoulder stress. Patient chairs with removable headrests are far more preferable. Head and neck comfort for the patient can easily be provided by a Tempur-Pedic pillow placed underneath the head and shoulders (Fig 1-5) while allowing the patient's head to be correctly positioned in the doctor 's lap (Fig 1-6). Figures 1-7 and 1-8 compare the changes in positioning required with the

Patient chair and headrest In observing hundreds of endodontists over a 20-year period, the author has concluded that one of the most significant impediments to good ergonomic technique involves poor patient positioning and chair ergonomics. The secret to working effectively under the micro scope is to move the patient chair, not the microscope. Nearly all endodontic procedures are performed with the patient in the Trendelenburg position, in which the patient is in the supine position with the feet higher than the head by 15 to 30 degrees. It is seldom necessary to change the patient from this position, whether you are working on the maxilla or the mandible or performing surgical endodontics. What the clinician needs is to be able to move the patient chair laterally in an east-west direction with either the knees or the legs while working under the microscope. For such motion to happen effort-

standard chair headrest and the removable headrest.

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Understanding Basic Ergonomic Principles

Fig 1- 6 Patient head positioned close to the doctor or assistant ' s lap.

Fig 1 - 7 (a and b) Headrest prevents proper patient positioning and requires bending from the waist.

Fig 1- 8 (a ) Headrest removed. Notice the upright position of the operator, (b ) Close- up view of the patient with the headrest removed and the operator in an upright position.

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Operatory Design and Ergonomics for Microscopic Endodontics

Fig 1-9 Ergonomically healthy doctor and assistant positioning.

Fig 1-10 Proper design of armrests for the assistant.

pletely eliminate shoulder and neck pain that is caused by spasms of the trapezius and sternocleidomastoid muscles. Because an assistant is required to have both right- and

Doctor and assistant stools The incidence of disability claims for both doctors and assistants is surprisingly high. A Dutch study3 reports that nearly half of all dentists will experience a disability that will prevent them from working at full capacity during their career. Similarly, almost 90% of dentists will suffer from some physical impairment of their back, neck, shoulder, arm, or wrist during their productive career that will impact their practice significantly. Therefore, proper posture and sitting positions are imperative in microscopic endodontics. Repetitive motion injuries are common, and it is rare to find an endodontist or assistant who has practiced for more than 10 years who does not have some type of physical problem with the neck, back, shoulder, or wrist. All of these injuries affect job performance and job satisfaction/fulfillment, increase working stress, and bring significant economic repercussions. Although repetitive stress injuries are complex in both their origin and course, all healthy ergonomic technique starts with correct posture and sitting positions, so it is imperative to pay attention to how one sits and positions oneself while working.

left-handed skills, having armrests appropriately positioned for the assistant is crucial (Fig 1-10). The standard halfcircle armrest found on most assistant stools is a very poor choice because it forces the assistant to be too far away from both the doctor and the assistant microscope and makes erect posture impossible, thus necessitating a Class V motion (bending at the waist) (Fig 1-11 ).

Posture and positioning during suctioning Because accurate suctioning is fundamental to compe tent assisting, it is important for an assistant to be able to perform this procedure erect and without muscular stress. In Fig 1-12, the assistant uses her left hand, with elbow on the armrest, to accurately position the suction tip. The handgrip used to hold the suction device also

deserves attention, as it is important to avoid stressful pronation of the wrist typically experienced by assistants performing suctioning on patients. Bending and twisting during assisting is one of the primary drivers of assistant injury and may very well be one of the major factors in assistant burnout. If assistants are physically fatigued from bending and twisting all day and return to their families at night physically exhausted, it will inevitably have a negative impact on job satisfaction and talent retention.

Proper armrest placement With correct posture and positioning at the microscope, it is possible to work in such a way where your postural support muscles are relaxed and at rest (Fig 1-9). Dual (ie, right and left), movable armrests are critical for both the doctor and the assistant, and their correct use can com-

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Understanding Basic Ergonomic Principles

Fig 1 - 11 (a ) Improper assistant ' s chair with forced bending at the waist, (b) Healthy, upright sitting position and relaxed posture for the assistant.

Fig 1-12 ( a and b ) Assistant suctioning position using the left hand from two viewing angles, (c and d) Proper hand position to eliminate fatigue.

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Operatory Design and Ergonomics for Microscopic Endodontics

Fig 1-13 (a and b ) Improper suction and mirror placement with resultant mirror splash, (c and d ) Proper mirror and suction placement that minimizes mirror splash. Notice how far away the mirror is placed from the site and where the suction tip is placed.

tion of the east-west rotational movement of the chair. If new construction is contemplated, the ceiling mount is far more preferable because access to the microscope from the doctor's side should require no more than a Class IV motion (Fig 1-14). Ceiling mounts over the patient's right or left hip position are less desirable than a rear-mounted ceiling location. The hip-mounted location can impede a patient's ingress or egress to the chair and may present a hazard, causing a patient to potentially strike their head against the microscope if they stand up too quickly. This problem is not present with rear-mounted installations. The microscope's range of motion, both vertically and horizontally, needs to be considered during mounting. The microscope should not be mounted so that it is ever needed at the maximum range of its extension

Proper suction placement Extreme accuracy in suction placement plays an important role in defogging the mirror and avoiding water-spray splash from the handpiece (Fig 1-13) in all phases of

endodontics, including conventional retreatment, and surgical endodontics where the ability to see cannot be compromised. Often clinicians are not aware of the increase in efficiency achieved by simply having accurate suction placement by their assistant. Even the distance of as little as 1 or 2 mm can make all the difference between a mirror that stays debris- and splash-free and one that does not.

Microscope mounting

arms. The author prefers the rear back wall or rear ceiling mount both for its ease of installation and ease of moving it into and out of the operating field (Figs 1-15 to 1-17 ).

The dental operatory is a confined space, and it requires careful planning to develop an effective ergonomic design. Because microscopes do not function well when they are used at the maximum extension of their arms, careful measurements need to be taken to ensure that the operator always has some degree of freedom of positional movement of the microscope. Patients vary in height and size, and an improper mounting can make treating patients outside the normal range difficult and uncomfortable. The choices for microscope mounting include floor, wall, and ceiling mounts. Floor mounts are very problematic for a variety of reasons mostly having to do with the restriction of patient access to and from the chair as well as restric-

Assistant/co- observation scope Assistant/ co -observation tubes (or scopes) are one of the greatest advantages of parallel-optics microscopes. A co -observation tube is attached to the beam splitter on the microscope, and a properly configured assistant 's scope allows the assistant to sit in an ideal upright position, always muscularly at rest for all endodontic procedures including surgical endodontics. The advan-

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Understanding Basic Ergonomic Principles

Fig 1-14 {a ) Microscope placement requiring only a Class IV motion to bring it into use. (b) Ceiling mount .

Fig 1-15 Back wall mount.

Fig 1-16 Side wall mount.

Fig 1-17 Ceiling mount. Scope ac cess using a Class IV motion.

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Operatory Design and Ergonomics for Microscopic Endodontics

Fig 1 - 18 Dual-axis assistant scope.

Fig 1 -19 (a) Dual-axis and inclinable binoculars on an assistant scope, (b) Range of motion of inclinable binoculars.

tage of this approach should not be taken lightly, and

fixed binoculars (Fig 1-19). If the co-observat ion scope is not configured properly, the assistant will not be able to achieve the ideal ergonomic sitting position for every procedure. Single- axis assistant scopes are to be avoided, as are fixed-angle binoculars, because these handicap the assistant ergonomically and will greatly compro mise the assistant's ability to function at a high level.

endodontists who take the time to train their assistants in this technique never return to using a microscope that does not have a co-observation scope. The configuration of the assistant 's scope is critical. It must be a dual-axis (not single-axis) scope that utilizes two degrees of freedom around two separate axes (Fig 1 -18). It must also have inclinable binoculars, not

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Understanding Basic Ergonomic Principles

Fig 1-20 (a ) Positioning of the doctor cart for Class III motions, (b ) Class III motion to the doctor cart.

Fig 1-21 Umbilicus connection to the doctor cart.

Many clinicians have a difficult time understanding the benefits of a co -observation scope. However, there are many advantages of a co -observation scope in endodontics: ( 1 ) enhanced teamwork and practice focus; (2) increased clinical competence; (3 ) increased efficiency; (4 ) retention of top assisting talent; (5 ) less guesswork on the part of the assistant; (6 ) preservation of the ergonomic health of the assistant; (7 ) more accuracy in the performance of critical assistant functions; and (8 ) promotion of a practice culture centered around clinical

side of the operator. It is imperative that the clinician not reach for handpieces, ultrasonics, or Stropko Irrigators (SybronEndo) in a way that requires any motion from the shoulder or any motion that requires lifting of the elbow off the chair armrest. The delivery cart should be easily positioned so that a single Class III motion is all that is needed to grasp any required device (Fig 1-20). Having a self -contained water supply and onboard compressor makes the cart even easier to move and minimizes the contents of the connecting umbilicus (Fig 1 -21).

Doctor cart or delivery system

Back wall design and assistant 's platform

Dental delivery units have their own ergonomic constraints for the endodontist who performs all procedures under a microscope. The common methods of dental delivery systems used in endodontics rear delivery or over the patient are very poor models for the microscopic approach. The circle of influence principle and the need to minimize the frequency of Classes III, IV, and V motions demand a mobile cart system delivered from the front

An ergonomically designed back wall and assistant's platform is critical to successful ergonomic practice, and the time spent designing the back wall and assistant's work area carefully will pay dividends. The back wall design should conform to the circle of influence principle, allowing the assistant to have ready access to all instruments and devices with minimal movement as well as access to the mouse, keyboard, and mon-

excellence.

—

—

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Operatory Design and Ergonomics for Microscopic Endodontics

Fig 1 - 22 Spatial relationship of the doctor cart , microscope, back wall, and assistant 's work area.

Fig 1- 23 Back wall design with the assistant ' s monitor.

Fig 1 - 24 Assistant ’s platform.

Fig 1- 25 Standard assistant positioning and back wall design.

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Understanding Basic Ergonomic Principles

Fig 1- 26 (a and b) Proper positioning of the assistant 's monitor allows continual assisting and digital recordkeeping simultaneously.

.

Fig 1- 27 fa and b) Improper monitor placement. The assistant must turn away from the assistant’s scope to enter data

itor while assisting. Building the assistant's platform or tray into the back wall has the advantage of creating a large platform in a compact space with full access to all instruments and devices using only Class III motions. The assistant's tray or platform needs to be positioned so that a sitting assistant can access the tray at postural rest in an upright sitting position. The assistant's monitor needs to be placed directly in front of the assistant, at eye level, so it is visible while the assistant is sitting at the microscope using the coobservation scope. Figures 1 -22 to 1-25 demonstrate the back wall, the assistant's platform, and their correct

moment without even turning the head. Such ergonomic

efficiency results in the clinician never being without an assistant, while the natural flow of procedures is not interrupted on account of the assistant being indisposed or otherwise distracted. Conversely, improper placement of the monitor handicaps the assistant and results in fragmentation of clinical procedures, contributing to frustration for both the doctor and the assistant. Figure 1-27 shows improper placement of the monitor and is unfortunately the typical placement seen in commercial dental operatory designs.

positioning.

Doctor monitor

Assistant monitor

Similarly, the doctor 's monitor should be placed so that he or she can view the monitor without turning the head . The doctor typically has a need to examine radiographs throughout the course of most procedures, so the monitor should be large, correctly positioned, and in a direct line of sight so turning of the head is not required. The author has found that a large monitor placed on the cart fulfills this need best (Fig 1 - 28).

As mentioned previously, the placement of the assis and is one of the most common errors made in operatory design. Ideal design allows the assistant to continue assisting while still being able to enter data. As shown in Fig 1 - 26, the assistant can view the monitor simply by averting his or her eyes for a brief

tant's monitor is critical

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Operatory Design and Ergonomics for Microscopic Endodontics

Fig 1-28 ( a and b) Doctor ’s monitor placed on the cart for direct line-of -sight viewing.

Common problems and solutions for creating an ideal ergonomic practice Problem Moving scope in and out of the

operating field Moving scope more than

Reason for the problem

Solution

Purchase a six-step microscope or a microscope that has the lowest magnification of

Magnification not low enough

2.2 X

necessary

Patient chair not easily moved

Purchase a chair that is easily moved back and forth

Inefficiency during procedures

•Too many Classes III, IV, and V motions •No armrests on doctor and assistant stools

•Practice and drill using only Class I and

• No assistant scope

•Obtain an assistant's scope

•Not a dual-axis assistant's scope

•Ensure proper assistant's scope

Assistant uncomfortable at scope

•Improper assistant stool •Improper patient and doctor positioning

•Chair headrest requires doctor and assistant Neck and/or back pain

to

bend at waist

•No doctor or assistant armrests •Poor patient positioning

Conclusion

Class II motions

configuration

•Correct the assistant stool •Correct doctor and patient positioning •Remove the patient chair headrest •Have adjustable armrests for doctor and assistant

•Place the patient in the Trendelenburg position

References

Efficient ergonomics in a microscope-centered practice requires a constellation of factors to be present. Frequently, this is a step-by-step process as the clinician gradually appreciates the value of working in such a manner. Table 1-3 summarizes some of the common problems and their solutions for creating an ideal ergonomic practice.

1. " Ergonomics: 1 - 2 Instrument Passing Technique " YouTube video, posted by TDO Software, January 1, 2012, https:// www.youtube. com/watch?v= MHBIrhlJaOM. Accessed 7 July 2014. 2. " Ergonomics: The Healthy Way to Work " YouTube video, posted by TDO Software, January, 22, 2011, https://www. youtube.com/watch?v=6VM64zpoxtY. Accessed 7 July 2014. 3. Hoevenaars JG. Dentist and disability: A matter of occupa tional disease ? [in Dutch]. Ned Tijdschr Tandheelkd 2002;109:207-211.

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CHAPTER

cott K. Bentkover, DDS

Setting Up Your Dental Operating Microscope for

Capturing high-quality digital images through a microscope is both highly rewarding and informative. Many authors have described the value of implementing digital photography in the dental office and how it can support:

•More effective diagnosis and treatment planning •Dental/legal documentation •Forensic documentation •Insurance verification •Patient/referral education and marketing tools •Communication with laboratories, dental team members, and colleagues1-3 The goal of this chapter is to convey the basic principles needed to get the clinician " up and running " with microscope photography utilizing equipment that may already be available.

Photography Basics Before we enter into the discussion of capturing photographic images through a microscope, a review of some basic photography concepts is in order. Table 2-1 defines terms such as resolution , aperture , depth of field, iris , magnification, focal length of the objective lens, International Organi zation for Standardization ( ISO ), shutter speed / exposure time , and white balance, which are referenced throughout this chapter. Illustrations for some of these terms follow. These concepts serve as an important foundation in mastering clinical photography skills.

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Setting Up Your Dental Operating Microscope for Photography

Table 2-1

Basic photography concepts

Photography concept

Resolution

Basic definition

Key principle (s)

•The sharpness and clarity of •Commonly measured in pixels, which are the smallest addressable element an image. in the image or display device. - Pixels are typically reported in terms of •Also refers to the ability of an megapixels. 78

imaging system to resolve detail in the object that is being imaged.4-6

•Megapixels are calculated by multiplying an image's pixel columns by pixel rows and dividing by one million.7-8

•Increasing the number of pixels will more accurately represent the original object (Fig 2-1).

Aperture

The size of the hole through which light travels through an optical system.9

•Directly relates to both the amount of light that is allowed into an optical system and the depth of field imparted into images captured through that system.

Depth of field

The distance between the nearest and farthest objects that appear acceptably sharp in an

•One of the single most important characteristics of a surgical microscope,

.

image (Fig 2-2) Iris

An adjustable aperture used to control the amount of light passing through a lens or optical system. (According to Webster 's Dictionary.)

Magnification

The process of enlarging the size of something such as an optical image. (According to the American Heritage Dictionary.)

Focal length of The distance from the plane the objective of the lens to the point that an lens image is in focus (Fig 2-3). (Note that this should not be confused with the focal length of a camera lens, which is discussed later.) International Organization for Standardization (ISO)

The standardized industry scale for measuring sensitivity to light.11 It pertains to the sensitivity of a digital camera 's image sensor.

Shutter speed, •The length of time (expressed also known as in seconds) a camera 's shutter exposure time is open when taking a photo-

graph.13 •The length of time that your

image sensor " sees " the scene you are attempting to capture 14

.

depth of field determines how possible it is to achieve a focused view of an object within an extended depth.10 •In microscopic endodontics, maximum depth of field is desired so as to give observers the greatest amount of detail and understanding. An • iris can be added to optical systems or lenses to constrict (in varying amounts) the aperture, which in turn increases or decreases the depth of field.10 Closing an iris in an optical system will decrease the aperture of the system but will increase the depth of field of that system. •A byproduct of decreasing the aperture of a system is to decrease the amount of light allowed through the system. Therefore, closing an iris is the desired method used to increase the depth of field of a system; however, other methods must be used to compensate for the loss of light that incurs. •Increasing the magnification decreases the depth of field. This can easily be

demonstrated when comparing the view of an object at low magnification with that of the same object at high magnification. •Example: An operating microscope might have 45 to 50 mm of depth of field at low magnification but only 2 to 3 mm of depth of field at high magnifica tion.

•Increasing the focal length of an objective lens will increase the depth of field

,

•Example: A 300-mm objective lens will be in focus farther away from a subject and have a greater depth of field than a 200-mm objective lens, so increasing the focal distance of an objective lens will increase the depth of field of the

system. •As the focal length of an objective lens is increased, the magnification of the

lens will decrease, which translates into greater depth of field and less magni fication at longer focal lengths.

•Measured in numbers, with the lower numbers (eg, ISO 100) being the least

sensitive to light and the higher numbers (eg, ISO 6400) being the most sensitive to light.11 •With increased sensitivity (ie, higher numbers), the camera sensor can capture images in low-light environments without a flash; however, higher sensitiv ity adds grain or " noise " to the picture (Fig 2-4), and too much noise may become objectionable at higher ISO settings.12 •Longer exposure times allow the shutter to be open longer, which allows more light to be captured by the sensor. •However, longer shutter speeds will allow more camera movement to be captured by the sensor as well, which might result in blurry images when too

much movement is captured by the sensor. •The actual speed chosen for a given picture will vary depending on the

operator's ability to control microscope movement and how much blur is acceptable. •Generally, the shutter speed should be set at 1/125th of a second or faster to minimize the effects of microscope movement on the image . White balance The process of removing unreal- •Adjusted to get the colors in images as accurate as possible.16 istic color casts, so that objects •Adjustments can be made manually by using the camera to record a truly that appear white in person are known white target or automatically by having the camera digitally determine rendered white in the photo.15 the proper white target for each image captured. •Most digital cameras used in microscope dentistry can detect white balance automatically.

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Microscope Armamentarium Important for Photography

1X 1

2x 2

5X 5

10 x 10

20 x 20

noiai itH

'

50 x 50

100 x 100

D U if iii

(Courtesy of Jared C. Benedict. Fig 2- 1 Visual example of resolution . Note that higher resolution is Fig 2- 2 Visual example of depth of field. achieved when more pixels are used.

)

Fig 2- 3 Visual example of focal length of the objective lens. (Courtesy Fig 2- 4 Visual example of ISO numbers. Note the added noise in the picture at the right due to the higher ISO number. (Courtesy of Nasim of Carl Zeiss.) Mansurov.)

Box 2-1

Complete list of accessories necessary for capturing digital images through a microscope

•DSLR photo adapter •Reticle for dominant eye side eyepiece •Light source •Ring flash* •DSLR camera body

•Assistant co-observation microscope •Dual-iris diaphragm •Beam splitter (Typically 50/50 beam splitters are recommended; however, other configurations are available.) •10 X eyepieces

*Note that the use of a flash is not mandatory and depends on the microscope manufacturer, light source intensity, and DSLR technology.

outfitting an operating microscope for photography requires several key accessories: a co - observation microscope, a dual-iris diaphragm, a beam splitter, a photo adapter, 10 X eyepieces, a reticle, a light source, a ring flash, digital single- lens reflex (DSLR ) camera body, and in some cases a supplemental ring flash (Box 2-1 and Fig 2- 5). Each of these essential microscope accessories is described in detail in the following sections.

Microscope Armamentarium Important for Photography For the purposes of this chapter, it is assumed that the practitioner already has a thorough understanding of the basic parts of the microscope (ie, objective lens, magnification changer, binoculars, and eyepieces). Properly

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2 Setting Up Your Dental Operating Microscope for Photography

Fig 2-5 (a and b) Key accessories necessary for microscope photography : dual- iris diaphragm (A); beam splitter (B) ; photo adapter (C), coobservation/assistant microscope (D); reticle (E) (note that the reticle is not visible in photo ) ; DSLR camera (F); ring flash (G).

Co- observation/ assistant microscope

Dual-iris diaphragm

Of all microscope accessories, the co-observation microscope (also referred to as an assistant microscope) is perhaps the most valuable (see Fig 2-5). It offers a three-dimensional view of the operative site and allows an assistant to work in real time with full optical clarity and depth of field that cannot be matched by a video monitor or any other device available on the market today. When working through the microscope, the assistant can do more than simply follow along, passing instruments or files with limited visibility. The co -observation microscope creates a four-handed microenvironment that allows the assistant to pass and receive instruments precisely at the location and in the orientation that the doctor needs them; to assist in diagnosis and pulp testing procedures; to suction directly adjacent to but not in obstruction of the doctor 's view; to perform countless mirror changes to maintain good visibility; to air-jet debris away from the operative site and/or the doctor 's mirror to maintain good vision; and to aid in the administration of anesthesia. An assistant scope also proves to be invaluable during microscope documentation. Tasks such as changing to a clean photography mirror, suctioning adjacent to the mirror for all clinical photographs so as to prevent fogging, remotely triggering the camera, changing the camera settings, and titling and organizing images are all facilitated with the assistant working through the microscope.

As mentioned earlier (see Table 2-1), an iris closes and opens the aperture, which respectively increases or de creases the depth of field of an optical system (Fig 2-6). An operating microscope has two optical pathways (one for each eye), so each pathway requires an iris—hence the term dual - iris diaphragm. Operating microscopes have inherently poor depth of field, especially at higher magnifications. Adding a dual-iris diaphragm to a microscope allows the operator to manually decrease the aperture of the microscope, thereby increasing the depth of field in the system. This invaluable component will impart a greater vertical range of focus in the viewing field, which offers a great amount of sharpness and detail in what the operator is viewing and planning to

-

photograph through the operating microscope. However, it is important to remember that closing the dual-iris diaphragm to increase the depth of field will decrease the amount of light passing through the optics. Therefore, the operator might need to make adjustments or add additional accessories to the system to increase the amount of light needed for optimal photography results When assembling the operating microscope, the operator has to place the dual-iris diaphragm directly be low the beam splitter ( described below) (see Fig 2- 5) Operating the dual-iris diaphragm is accomplished either by pushing a sliding bar mechanism to the left or right (in Global Surgical models) or by turning a serrated dial (in Carl Zeiss and similar models) toward or away from the operator (Fig 2-7). Either of these motions will open and close the iris's mechanism. However, at the time of this writing, only Zeiss's dial mechanism has a click -stop in each position, making the adjustment both reproducible and one that can be accomplished without looking at the device.

. .

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Microscope Armamentarium Important for Photography

Fig 2- 6 (a ) Image taken with the dual iris wide open and therefore with less depth of field and more light (ISO 400). (b) Image taken with a closed dual iris and therefore with more depth of field but less light (ISO 8000). Closing the dual iris shows more detail but will require additional light , higher ISO, or both.

Fig 2-7 Double-iris diaphragm (Carl Zeiss) ( left ) and dual-iris diaphragm (Global Surgical) (right ).

Beam splitter

through to the operator's eyepieces. For exampie, the Zeiss 20 beam splitter (Carl Zeiss) sends 80% to the eyepiece and only 20% to the side port, and the Virtual Beamsplitter (Global Surgical) sends 96.5% to the eyepiece and only 3.5% to the peripheral port (Fig 2-9). Allowing more light to pass to the operator's eyepieces translates into a brighter image, where the operator can see and focus more sharply while less light is sent to the camera. Beam splitters that give more light to the operator's eyepieces were originally designed to work well with video cameras due to their heightened light sensitivity. DSLR cameras were not so fortunate and performed poorly with these beam splitters (reduced light to the side port ) because light is a valuable and limited commodity in microscope photography and is the big gest obstacle to acquiring great photographs.3 As DSLR camera technology has continued to improve with higher ISO capabilities, so has the application of these beam splitters where less light is sent to the side to pass

The beam splitter divides (splits) the light traveling through the microscope between that which will eventually go on to the eyepieces and that which will continue to either one or two side ports. Peripheral accessories such as a DSLR camera, a video camera, or an assistant microscope can easily be attached and removed from the side ports. Typically, beam splitters have two side ports, although most manufacturers also make a single side port version for those who need only one peripheral device. The two -port beam splitter houses two cube prisms (one for each optical pathway of the microscope), which splits the light beam so that a portion goes to the side port and the remainder continues on to the eye piece. The most common type is a 50 / 50 beam splitter, which directs 50% of the light to the eyepiece and 50% to the side port (Fig 2- 8). Other beam splitter configura tions exist that are designed to allow more or less light

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Setting Up Your Dental Operating Microscope for Photography

Fig 2- 8 Diagrammatic view of a 50/50 beam splitter. Each Fig 2- 9 Virtual Beamsplitter (Global Surgical) (bottom prism divides or “splits” the light in half so that 50% con- left ) and 50/50 beam splitter (top right ).

tinues on to the eyepieces and 50% goes to the side port.

port. For example, instead of

er, the most appropriate choice for dentistry is 10 x due to ergonomic requirements. This becomes clear when

equally splitting the light, the Virtual Beamsplitter actually reflects 3.5% of the viewable light via a small, fully reflective disc in the center of the viewing field (see Fig 2-9). This small-diameter reflective surface also decreases the aperture of the optical pathway, thereby increasing the depth of field of the resulting image. This combination will result in darker images with good depth of field, which, when coupled with a camera capable of shooting at higher ISOs, can produce images with excellent depth of field and lighting without the use of a dual iris. Therefore, newer generations of DSLR cameras have allowed some users to forgo the use of a dual iris once they make the necessary lighting changes through altering the ISO in the camera. Finally, it is important to remember that regardless of the type of beam splitter used, the shutter speed should not be set below 1/125th of a second.

considering that 12.5 X eyepieces have 25% more magnification than 10 X eyepieces. When a clinician commits to working entirely through an operating microscope, procedures such as diagnosis, administration of anesthesia, evaluation of quadrant occlusion, placement of rubber dam, implant surgery, temporomandibular joint evaluation, and quadrant photography are all facilitated by the lower magnification of the 10 x eyepieces. Finally, the eyepiece magnification also affects the assistant 's perspective, where the eyepieces of the co-observation microscope need to have equivalent (1Ox ) or perhaps less (8 x ) magnification than the doctor's view. The assistant's tasks would be greatly impaired by having the reduced field diameter and decreased depth of field if the eyepieces had a higher magnification. Eyepiece power affects the magnification of the entire optical system, which in turn can also affect the choice of photo adapter. Utilizing 10 x eyepieces translates into the operator viewing the field at a lower magnification, and because it is most desirable to have photographic images at or near the magnification of what is seen through the microscope, a lower-magnification photo tube in the focal length range of F = 220 mm is required. The inverse of this is also true: In a microscope where the operator is using 12.5 X eyepieces, a highermagnification photo adapter should be employed to make sure that the camera is capturing close to but not greater than what the doctor is seeing through his or her eyepieces.

10x eyepieces The primary function of the eyepieces in an operating microscope is to project and magnify an image for the user. A secondary function is to allow the user to individually adjust a diopter setting (optical power to switch from near to far focus) to equilibrate each eye so that all parts of the microscope are in focus on the same plane (see section on parfocal adjustment later in this chapter). Current operating microscope eyepieces are called wide field, because they provide a wider field of view than earlier generations of eyepieces, and high eyepoint, which means that the eye can be farther away from the lens of the eyepiece and still allow the user to see the image. This facilitates the use of eyeglasses and also allows the operator to keep his or her eyes at a short distance from the eyepiece to avoid continually bumping or moving the microscope. Eyepieces are available in many different powers, the most common choices being 10 x and 12.5 X ; howev -

DSLR photo adapter The DSLR photo adapter, which attaches the camera body to the microscope, is a cylinder with lenses and a mirror (or prism) that carries the light to the camera so that it focuses

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Microscope Armamentarium Important for Photography

Fig 2-10 Photo adapters: (a ) F = 220 (Carl Zeiss); (b) DCA-220 (EIE2); (c) DSLR XMount (Global Surgical); (d) F = 340 (Carl Zeiss).

directly on the camera sensor and fills it to the maximum level.4 It basically acts as a photographic lens that attaches the camera body to the microscope. This small accessory is fraught with much controversy as there are many criteria that contribute to a superior photo adapter, such as focal length, light transmission, lens quality, image quality, construction, centering ability, weight, and ease of connecting and disconnecting cameras. Although all are important, due to the scope of this writing, only focal length is discussed here. The focal length of a camera lens refers to the distance between the lens and the image sensor when the subject is in focus, usually stated in millimeters.17 In photography, camera lenses with a longer focal length produce highermagnification images compared with lenses of a shorter focal length. Most photo adapters available on the market have a focal length of 170 mm (lower magnification) to 340 mm (higher magnification), so some have twice the magnification of others. Images taken at a magnification that is too low will not fill the image sensor of a DSLR camera, causing a vignetting effect where the image periphery is darkened, producing the effect of a dark circle around the image. Images taken at higher magnification will fill the image sensor, but as the magnification increases, the depth of field decreases, which can lead to a problem where the photo adapter's depth of field is less than that of the microscope. This translates into out-of-focus images; while the operator might be seeing an image in focus through the microscope, it will be outside the depth of field of the photo adapter, so the camera will see it as out of focus. There are several other concerns related to the use of higher-magnification photo adapters. When the vi-

sual frame of the microscope is greater than what the camera can see, accurate framing becomes more challenging. Also, a basic principle of optics states that light intensity decreases as magnification increases, which means that higher-focal length adapters will

produce darker images compared with their lowerfocal length counterparts. Finally, higher-focal length lenses use more lens glass and put the camera body farther away from the lens, thereby creating additional light loss and compounding the effect of the highermagnification light loss. For all of these reasons, when today's DSLR camera bodies (APS-C sized sensors) and microscope systems are considered, the preferred focal length range for a photo adapter is 200 to 250 mm (Fig 2-10).

Reticle Another simple component in the microscope photography setup is a reticle, which appears similar to a crosshairs or dotted circle in a gun sight and is placed in one of the doctor 's eyepieces. This often forgotten yet indispensable little component offers the benefit of allowing the operator to easily center and frame every image as it is captured. Without it, the operator will find that centering becomes a frustrating task, whereas once a reticle is utilized, off -center images will never be an issue again. It is important to determine which eye is the doctor's dominant eye, as the reticle will be placed in the eyepiece corresponding with that eye. Although the use of an assistant co - observation system is highly beneficial, it is not necessary to place a reticle in the assistant 's eyepieces as well as the doctor ' s.

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Setting Up Your Dental Operating Microscope for Photography

Light source The four types of light sources currently available for microscope use are halogen, metal halide, light-emitting diode (LED), and xenon. While all light sources vary by manufacturer, fiber-optic cable quality (broken fibers can severely affect the light output of the microscope), and lamp age, the source with the highest initial intensity is xenon (up to 200 kLux), followed by LED (65 to 85 kLux), metal halide (50 kLux), and halogen (50 to 65 kLux). Xenon lighting also offers the best color temperature (5,400 to 5,500 K) because it is most similar to daylight (5,500 to 6,000 K). However, regarding color temperature of LED lighting, there is wide variation in the industry, and it is difficult to generalize. For example, some metal halide and LED light sources (5,500 to 6,000 K) approximate that of xenon, while some are much higher (8,000 K). Halogen light sources (3,500 K) have a color temperature that is skewed toward the red end of the spectrum, which makes them a poor choice as the sole source of light for photography. Finally, although xenon light sources offer the best color temperature and light intensity, consideration should be given to the high cost of xenon lamps versus the life span, intensity, and color temperature of LED light sources. Therefore, readers should carefully

weigh all factors when selecting a light source.

System type-C [ APS-C] sized sensors) as opposed to full18 frame cameras (or 35-mm frame-sized sensors). Although full-frame, or larger-sensor, cameras can capture more detail ), cropat higher ISO settings (commanding a higher price range ISO the in well surprisingly do bodies frame camera piccapturing , photography microscope in typically found frame tures with the same level of quality. Additionally, crop center sensors are smaller, so they only capture, or crop, the , of the image that a camera lens sends to the sensor thereby producing pictures with a higher magnification than a full-frame sensor camera body using the equivalent lens. In other words, the larger-frame cameras produce images with lower magnification and require a higher-focal length photo adapter (300 mm to 340 mm) to produce an image of equivalent magnification to a crop-frame camera, which negates some of the advantages the larger-sensor camera can offer. Interestingly, the higher- end, crop-frame camera bodies currently available on the market offer marginally detectable image -quality advantages over older and more affordable cameras, so it pays to do a little research before purchasing a new camera body for your microscope. Finally, recent advances have led to a substantial decrease in the size (and weight) of both the APS-C and full-frame sensor cameras, which can improve the stabil ity of a microscope that has also been equipped with a co-observation scope for use by an assistant.

-

Ring flash

Setting Up Your Microscope

Microscopes equipped with halogen, metal halide, and even many LED light sources usually do not supply enough light to capture high-quality DSLR images when a dual-iris

Once the proper components have been obtained, the final assembly of the microscope can be addressed as described in Box 2-1 and depicted in Fig 2-5. During the process of assembly, it is important that the microscope arm balancing mechanism is adjusted so it can accept the weight of the additional accessories. The next step is to input the basic settings on the camera. The recommended settings listed in Box 2-2 can be used as a starting point and altered as needed, although the majority of users will find them sufficient. When capturing images through the microscope, a good practice model is to keep the process as simple and reproducible as possible. Additionally, the photography equipment and settings should be programmed to capture high- end images on every patient. Attempting to alter images "postproduction" through programs such as Photoshop, PhotoPlus, or GIMP (the GNU Image Manipulation Program) is extremely time-consuming and should be avoided. Only a small percentage of individuals make minor modifications with these programs

diaphragm is being used for maximum depth of field. In these light-deficient environments, it is beneficial to add a macro ring flash with a guide number (strength) of at least 43 feet at ISO 100. Ring flashes such as the Macro Speedlight SB-21B (Nikon) and the Macro Ring Lite MR -14EX (Canon) should suffice. Operators might also find that the addition of a ring flash is necessary or at least helpful even when the most powerful xenon light sources and high-end microscope systems are used. Fortunately, as camera sensor quality continues to improve, allowing images to be acquired at higher ISO settings with less noise, the need for a ring flash will become less of an issue.3

DSLR camera body The DSLR camera body sometimes receives more attention than is necessary. A common misconception is that high-quality digital images can only be achieved using the latest, most expensive professional camera body outfitted with many high -end features. To the contrary, excellent endodontic microscope images can be obtained with very simple camera bodies that have been available on the market for many years. It is important to understand that most DSLR camera

accommodate use of photographs for lecturing or publishing purposes. Therefore, operators will find that once their microscope photography setup is complete, capturing great images might require little to no modifications of the ISO, light intensity, or dual-iris settings during patient treatment.

to

bodies that are applicable to the operating microscope environment are crop-frame cameras (or Advanced Photo

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Setting Up Your Microscope

DSLR camera settings

Box 2- 2

•Image quality: Large-Fine, Medium-Fine, or Small-Fine*

•Manual •Flash off •TV (Shutter priority) 1 /125 s •ISO 200 (with flash) or 400-1600 (without flash)** •Exposure compensation: None

•White balance: Auto

•Metering mode: Center weighted •Drive mode: Single shot •Picture style: Standard

*ISO can vary depending on microscope manufacturer and light source.

at a very high ISO setting, some cameras will allow " High ISO Speed Noise Reduction " to be turned to *When shooting on your image size preference (choose small, medium, or large), but always set the compression to " Fine."

ON to improve image quality.

TDepends

Box 2- 3

Two methods to achieve parfocal adjustment*

Method 1

Method 2

.

1. Turn on the power to the microscope. 2. If you wear eyeglasses, roll back (in Global Surgical models) or dial down (in Carl Zeiss models) the eyecups to shorten them. 3. Position the microscope over a dot on a white piece of

1 Pull off the binocular head with eyepieces attached. 2. Set the eyepieces at high: plus (+8). 3. Relax the eyes by looking at infinity. 4. Do one eye at a time. 5. Look at a very distant object through the binocular. 6. Roll the eyepiece through focus until the image is sharp 7. Repeat a few times until you have confidence in the settings. 8. Record the settings for future use. 9. Repeat this procedure every few months to accommodate for changes in vision.

.

paper.

4. Set both eyepiece diopter settings to 0. 5. Position the fine focus to the middle of its range. 6. Adjust the interpupillary distance to " One circle of light." 7. Focus the image at the highest power using the fine focus knob only to get the clearest image. 8. Being careful not to physically move the microscope,

switch to the lowest power and then focus one eyepiece at a time with one eye closed while turning the diopter ring on the open eye to sharpen the image Lock into

.

place.

9. Focus the other eyepiece with the first eye closed and

lock the second eyepiece into place. 10. Change the magnification to the next highest setting and check each eye for sharpness and adjust if necessary. 11. Stabilize the microscope so that the assistant can go through the exact same sequence on the co-observation scope to set his or her diopters. 12. Repeat several times to confirm the settings. 13. Record the settings for future use. 14. Recheck every few months to accommodate for changes

.

in vision

*Compiled from a combination of original PERF documents, the Zeiss instruction manual, and a TDO Chart posting by Dr Eric Herbranson

Parfocal adjustment

a microscope are out of focus. Box 2-3 describes two methods that can be used to achieve parfocal adjust ment. Initially, this exercise should be performed several times a day throughout the first week until a consistent setting is achieved. However, it might need to be re peated every few months to accommodate for changes in the operator's vision (ie, eyeglass/contact lens prescription changes). Finally, it is also important to under stand that a user's eyepiece diopter values will vary from one microscope to another.

The parfocal adjustment (also known simply as parfocus ) is necessary to ensure that all the parts of the microscope are focused at the same plane. It is the single most important adjustment to make to a microscope when using a camera (video or DSLR) and/ or a coobservation scope. If the parfocus is not accurate, the camera(s) and the assistant scope will not be in focus when the operator has a sharp image. This is the most common explanation as to why images captured through

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Setting Up Your Dental Operating Microscope for Photography

Fig 2-11 (a ) Dual-iris (Global Surgical) setting closed so as to maximize depth of field for photography, (b) Dual iris wide open so as to maximize light while operating.

Transferring images from the camera to the computer

Common Microscope Photography Scenarios

Connecting an active USB extension cable from the camera to the computer allows for continuous image transfer and prevention of data loss and can save an enormous amount of time. Programs such as DSLR Remote Pro (Breeze Systems), EOS Digital Solutions (Canon), and Capture NX2 (Nikon USA) not only ensure safe transfer and storage of photographic images but can also take the place of a wireless remote. Remote activation of the camera is highly recommended because manually pressing the shutter release button will cause subtle movements of the microscope and affect image sharpness.

Microscopes with sufficient light for

photography As mentioned earlier, a primary component to capturing high-quality images is the dual iris, which, when closed to maximize the depth of field, will further limit light availability. A good rule to follow is to try to photograph at a predetermined dual-iris position, as the lighting environment is relatively consistent throughout a given procedure and might require only minor "tweaking" of the iris position from one type of scene to the next. A relative starting point for a Global Surgical dual-iris setting is to allow only 1 cm of slider bar to be exposed on the left side of the bar (Fig 2-11). It also might be helpful to inscribe a pencil mark at this position until it can be done by sight looking at the bar, as there are no reproducible marks on the mechanism. An equivalent starting point on the Zeiss dual iris is to have it closed all the way or only one or two clicks open from the closed position. Then, through trial and error, the operator should take some sample images on a set of endodontic files to find the corresponding ISO that will make that dual-iris position produce adequate lighting for a desirable image. The goal is to obtain a very close set of parameters (see Box 2- 2) for a specific microscope setup so that only the dual-iris position might vary slightly throughout a procedure to capture the most superior images; however, if any significant increase in light is needed, it is better to increase the ISO than to move too far away from these iris positions so as not to sacrifice depth of field. If the dual iris is closed to the proper position with the ISO of the camera set at the maximum level (which varies by camera and manufacturer) and the

Other essential tools and software Purchasing an AC adapter power supply for the camera will avert frustrating interruptions in patient treatment flow caused by battery and system failures. Additionally, high-reflectance mirrors, such as those made by Zirc and Excellence in Endodontics 2 (EIE2), reflect more light than typical dental mirrors. EIE2 mirrors also have a bendable neck—a notable ergonomic benefit—as well as a higher degree of flatness compared with other clinical mirrors, which translates to less distortion in the final image. Finally, the use of an office software system that also captures and manages images (eg, The Digital Office) is strongly recommended. To help shorten the photographic learning curve, two common photographic scenarios (as well as how to operate them) are presented here: ( 1 ) microscopes with sufficient light for photography and (2 ) microscopes with insufficient light for photography. If the reader is not certain as to which category a particular system falls into, simply follow the first scenario; if dark images are obtained, then continue on to the second scenario to remedy this common issue.

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References test images are still too dark, then it should be assumed

utilizing a flash, the operator can work with very little concern as to the light source intensity, as the majority of the light in the images comes from the flash.

that this particular microscope does not have enough light intensity for that camera, and the reader should refer to the later section ( " Microscopes with insufficient light for photography ") to remedy this situation. The clinician should also observe carefully that setting the ISO to a very high level may lead to unacceptable graininess in the images, which is also discussed below. Typically, microscopes with xenon or newer-generation LED light sources will provide sufficient light for capturing high-quality photography with newer-generation cameras. Remember that fiber-optic cable quality and lamp age can also affect light output of a microscope that utilizes a fiber-optic cable. When the practitioner finds that excellent images can be taken at an ISO within the capable range of the camera being used, one of three methods can be employed to capture images:

Conclusion Mastering good clinical photographic skills should be a goal for every clinician. This chapter can be used as a reference on how to get started utilizing microscope photography with the current knowledge and readily available equipment. The doctor and the assistant will find that taking superior clinical photographs and communicating with images will be one of the most rewarding aspects of clinical practice.

References

1. The clinician should operate the microscope under

normal circumstances with a moderate to low light intensity setting and the dual iris wide open. Then, when taking a picture, the dual iris should be closed and the light intensity increased to the maximum. By following this method, the clinician must determine the appropriate ISO that allows a high-quality image to be taken. It may be necessary to open up the dual iris or increase the ISO to compensate for clinical cases where there is a slight deficiency in light. 2. The clinician should operate the microscope and capture images at the maximum light intensity setting with the dual iris closed all the time. Then, if more light is required when taking a picture, the clinician will either slightly open the dual iris or increase the ISO. 3. The clinician should operate the microscope at the maximum light intensity with the dual iris wide open and then close the dual iris when taking a picture; the clinician can alter the dual-iris position or ISO slightly when more light is required.

1. Ahmad I. Digital and Conventional Dental Photography: A Practical Clinical Manual. Chicago: Quintessence, 2004. 2. Terry DA, Snow SR, McLaren EA. Communicating digitally with the laboratory: Design, impressions, shade, and the digital laboratory slip. Inside Dent 2009;5:62-67. 3. van As GA . Digital documentation and the dental operating microscope: What you see is what you get. Int J Microdentistry 2009;1:30-41. 4. Camera & Imaging Products Association. CIPA DCG-001Translation-2005. Guideline for Noting Digital Camera Specifications in Catalogs, http:// www.cipa.jp/std/documents/e/ DCG -001_E.pdf. Accessed 11 August 2014. 5. International Imaging Industry Association. ANSI/ I3A IT10.7000-2004. Photography - Digital Still Cameras - Guidelines for Reporting Pixel- Related Specifications. International Imaging Industry Association, 2004. 6. RatcliffS, Bush DE, Fondriest JF. Digital Dental Photography: A Clinician's Guide. Key Biscayne, FL: LD Pankey Dental Foundation, 2004. 7. Foley JD, Van Dam A. Fundamentals of Interactive Computer Graphics. Reading, MA: Addison-Wesley, 1982. 8. Graf RF. Modern Dictionary of Electronics. Oxford: Newnes, 1999:569. 9. Terry DA, Snow SR, McLaren EA. Contemporary dental photography: Selection and application. Funct Esthet Restor Dent 2007;1:37-46. 10. Carl Zeiss. Depth of field OPMI application tip # 2. Informed 2006;2:14-17. 11. Callow R (ed). What does ISO stand for in photography and why do I need to know ? Bright Hub 2013. http://www.

Microscopes with insufficient light for

photography When halogen, metal halide, or even some older LED light sources are used, today's cameras do not have the capacity to capture high-quality microscope pictures. Moreover, combining one of these light sources with a dual-iris diaphragm will further limit light availability. For this setup, adding a macro ring flash source is strongly recommended. With the addition of a ring flash, the dual iris can remain wide open throughout the duration of a procedure and then can be closed only when a pic ture is taken. This is necessary because the view through the eyepieces is likely to be too dark if the dual iris is left closed during the procedure. The ISO is then set to obtain proper lighting at this dual-iris position. When

brighthub.com /multimedia /photography / articles / 72927. aspx. Accessed 21 July 2013. 12. Mansurov N . Understanding ISO—A beginner 's guide. Photography Life 2009. http: //photographylife.com/ what -is-isoin-photography. Accessed 21 July 2013. 13. Ray SF. Camera features. In: Jacobson RE (ed). Manual of Photography: A Textbook of Photographic and Digital Imaging, ed 9. Burlington, MA : Focal Press, 2000:131-132.

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Setting Up Your Dental Operating Microscope for Photography 16. Rowse D. Introduction to white balance. Digital Photography School http://digital-photography-school.com/introductionto-white-balance/. Accessed 21 July 2013. 17 Nikon. Digital SLR camera basics, http://imaging.nikon.com/ history/basics/. Accessed 27 July 2013. 18. Harmer J. The difference between full-frame and crop sensor DSLR cameras. Improve Photography 2011. http://improvephotography.com/699/ the -difference -between-full -frame and-crop-sensor-dslr-cameras/. Accessed 28 July 2013.

14. Rowse D. Introduction to shutter speed in digital photogra phy. Digital Photography School. http://digital-photogra phy-school.com/shutter-speed. Accessed 21 July 2013. 15. McHugh S. Tutorials: White balance. Understanding White Balance. Cambridge in Colour 2013. http.V/www.cambridgeincolour.com/tutorials/white-balance.htm. Accessed 21 July

,

.

2013.

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CHAPTER

3 Scott K. Bentkover, DDS

Setting Up Your Dental Operating Microscope for

More and more clinicians in the dental and medical professions are becoming proficient in microscope videography. The underlying drawback of relying solely on still photography is that it doc uments only static findings, while a short video clip or display from a live video feed can reveal far more information.1 However, this should be tempered with the understanding that learning how to use video requires preparation and patience, because the financial investment and postproduction time required in video editing and manipulation can be staggering. This chapter describes the armamentarium required to acquire and display video from a dental operating microscope to help the clinician navigate through technology that is currently available.

Videography Basics While many of the basic photography concepts (ie, aperture, depth of field, shutter speed/exposure time, white balance) covered in chapter 2 will aid the reader in understanding videography, a review of several new concepts is in order. Table 3-1 defines terms such as resolution, analog video, digi tal video, high -definition ( HD ), aspect ratio, progressive / interlaced scanning , frame rate, and gain, which are referenced throughout this chapter. These concepts serve as an important foundation to help the reader quickly master clinical videography skills.

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Setting Up Your Dental Operating Microscope for Videography

Table 3-1

Basic videography concepts

Videography Resolution

Analog video

Digital video

Key principle(s)

Basic definition

concept

The understanding of resolution , or sharpness Video is considered to be a string of multiple frames (still and clarity of an image, is broadened with images) being shown in a given second. As the lines per frame video resolution relative to both analog and increase in a given video, so will the resolution. digital formats, which are the formats that are currently available for video capture through a microscope. Analog video is a video signal transferred by •Each frame is composed of horizontal lines, also known as TV analog coding methods. An analog color vidlines, resulting from the derivation of analog video from the eo signal contains luminance, brightness (Y), television industry.2-3 and chrominance (C) of an analog television •Typical analog video resolution in North America and Japan image. Composite video combines all video uses the National Television System Committee (NTSC) information into one signal. Component video standard 480 lines of resolution, while in Europe and many Asian and African countries, the Phase Alternating Line (PAL) improves signal clarity by separating the comstandard is used, which offers 576 lines of resolution.2 ponents of a video signal so that they do not interfere with each other and include formats •Higher analog video resolution ranges from 800 to 1,000 lines such as S-video (Y/C), RGB, and YPBPR. of resolution.

•Each frame is composed of horizontal lines, with the modi-

Digital video comprises a series of orthogonal bitmap digital images, or frames, displayed

fication that each line is digitally sampled, or processed to separate the continuous signal into discrete picture elements, to create a number of pixels per line.3 •The more lines per frame, the higher the image resolution. The more pixels per line, the higher the resolution of each line.3

in rapid succession at a constant rate via a

digital signal.

High-definition (HD)

Aspect ratio

Progressive/

interlaced scanning

Frame rate

Higher-resolution digital video (now commonly known as high-definition [ HD] format) is defined by the Advanced Television Systems Committee (ATSC) to have either 720 or 1,080 lines per frame.3

•The pixel resolution of HD video has 1,280 pixels per line and

The ratio of width to height of an image.4

•Two aspect ratios presently obtainable in microscope videography are 4:3 and 16:9. •The 4:3 aspect ratio, seen in standard definition (SD), means

•Progressive (480p, 720p, or 1080p) scan video sources display both the even and odd scan lines of the entire video frame on the TV at the same time.5-6 •Interlaced (480i, 720i, or 1080i) scan video sources display even and odd scan lines as separate images, a fraction of a second apart.5-6

The number of frames displayed per second

(fps).

720 line measures (1,280 x 720), and the higher 1,080-line video uses either 1,440 or 1,920 pixels per line (1,440 X 1,080 or 1,920 X 1,080). •At the time of this publication, 4K (also known as ultra HD) , which has a resolution of 3,840 pixels X 2,160 lines, has not yet made it into the microscope video camera market, but it is beginning to enter into the consumer camera market, which will certainly be adaptable to operating microscopes.

that for every 4 inches of width in an image, there will be 3 inches of height (ie, screen will be 33% wider than it is high). •The 16:9 aspect ratio, utilized in HD, means that for every 16 inches of width in an image, there will be 9 inches of height. Unlike the 4:3 aspect ratio, a 16:9 aspect ratio is 78% wider than tall4 (Fig 3-1). •Modern HD video is only available in a 16:9 aspect ratio. •Respectively indicated with either a "p" or an "i" after the lines of horizontal resolution number. •The even scan lines image is drawn on the screen first, and then the odd scan lines image is drawn on the screen 1/60th of a second following the first image. A pair of these even and odd scan line image fields make up one video frame. •Progressive video contains more data than interlaced video and, as a result, the video imaging appears sharper and more detailed, with no motion artifacts visible when watching quick-motion sequences, because the entire image is on the screen at once.5 However, progressive video cameras are more expensive and require more data to be transferred to either a monitor or recording device.

Progressive video frame rates can range from 60 fps to 120 fps; however, any type of video with a frame rate of less than 24 fps will appear as " jumpy " or less true to life.

[ 30I

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Microscope Armamentarium Important for Videography

Basic videography concepts

Videography concept

Gain

Basic definition An electronic amplification of the video signal, where the signal is boosted by adding more voltage to the pixels on the imager (ie, charge-coupled device [CCD] or complementary metal-oxide semiconductor [CMOS]), causing them to amplify their intensity and therefore brighten the image.7

Key principle(s) for Stan•The video equivalent to International Organization dardization (ISO); as the gain increases, so does the brightness and graininess of the resulting video. to light compared •Video cameras have a higher sensitivity with still cameras and are capable of functioning quite well in the most light-deficient microscope environments. Therefore, many of the methods utilized to increase the light intensity for digital single-lens reflex (DSLR) photography through a microscope are not usually necessary when utilizing a video camera.

Box 3-1

Complete list of accessories necessary for capturing video through a dental operating microscope

•Beam splitter •Video camera adapter •Video adapter iris (optional) •Reticle

•Video cables

•Video display/monitor •Video camera •Recording device (optional)

Fig 3- 1 Aspect ratio example. There are two aspect ratios available in microscope videography: 4:3 and 16:9. The 16:9 aspect ratio is a product of the movie industry to allow more information in a given frame. 4

vice and the monitor, must be capable of supporting HD- quality video.8 Finally, there are more accessories

Microscope Armamentarium Important for Videography

and setups available in videography than photography, which makes each configuration both user- and system-specific.

Properly outfitting a microscope for videography requires several key accessories: a beam splitter, a video camera adapter, a video adapter iris, a reticle, video cables, a video display/monitor, a video camera, and in some cases a recording device (Box 3-1). While similar to those used in photography, each accessory in the video process (or video chain ) works in unison, and the final video quality is directly related to the lowest performing accessory in the video chain.8 For example, if HD- quality video is desired, then each accessory, from the video camera to the connecting cables to the recording de-

Beam splitter A beam splitter is required in all microscope video sys -

tems. As explained in chapter 2, the beam splitter divides each light path in the microscope to allow a digital single- lens reflex (DSLR ) camera, video camera, or

assistant co- observation scope to be attached to the microscope. Table 3-2 lists the variety of beam splitters

available for videography use and the key features of

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Setting Up Your Dental Operating Microscope for Videography

Table 3-2

Types of beam splitters and combined video modules with details of their components % Light split to

Integrated cameras

port or camera

Eyepieces

Focal length of video lens

50

50

N/A

No

N/A

N/A

N/A

N/A

3.5

96.5

N/A

No

N/A

N/A

N/A

N/A

50

50

N /A

No

N/A

N/A

N/A

N/A

25

75

F = 80 mm

Yes*

50

50

N/A

No

N /A

N/A

N/A

N/A

50-L 20-R

50-L 80- R

N/A

No

N/A

N/A

N/A

N/A

Zeiss 20 beam splitter (Carl Zeiss)

20

80

N/A

No

N/A

N/A

N/A

N/A

Zeiss 50 beam splitter (Carl Zeiss)

50

50

N/A

No

N /A

N/A

N /A

N/A

Zeiss 70 beam splitter (Carl Zeiss)

70

30

N/A

No

N/A

N/A

N/A

N/A

MediLive compact video camera (Carl Zeiss)

20

90

F = 60 mm

Yes*

MORA interface with documentation port (Carl Zeiss)

30

70

N/A

Yes

N/A

N/A

N/A

N/A

Pico integrated HD video camera (Carl Zeiss)

20

80

F = 50 mm

Yes

N/A

20

80

F = 48 mm

Yes

N/A

N/A

F = 50 mm

Yes*

VOL-mount camera (Carl Zeiss)

20

80

F = 80 mm

Yes*

50/ 50 beam splitter

50

50

N/A

No

Side

Product name (manufacturer ) 50/ 50 beam splitter (Global Surgical)

Virtual Beamsplitter (Global Surgical) 50.50 beam splitter (Leica Microsystems)

Integrated HD camera (Leica Microsystems) 50.50 beam splitter (Seiler Instrument)

Dual-port beam splitter (50/50-left [L] side and 20/ 80-right [ R] side) (Seiler Instrument)

PROErgo integrated video camera (Carl Zeiss)

TRIO 610 HD video camera system (Carl Zeiss)

(Zumax Medical)

Built-in

SD

HD

1CCD

3CCD

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

CCD, charge-coupled device. *Built-in to a single module where the module is easily removable from the microscope by the user.

each. The most common variation, a two- port 50 / 50 beam splitter, allows the light path to be equally divided between the eyepieces and the side ports. Other video beam splitter components contain integrated video lenses and/ or cameras and offer an ergonomic, low-pro file, and budget-friendly means of adding videography capabilities to a microscope. However, it is important to understand that some manufacturers ' integrated video systems are not easily upgraded, so these systems may not be the best choice for users who prefer to frequently change video cameras as technology evolves.

Video camera adapter The video camera adapter (also known as a video lens, video adapter , or cine adapter) (Fig 3-2), like a photo adapter, is a cylinder with a lens that focuses the image directly on the camera sensor (or chip in video terminology). However, the cylinder may or may not contain a mirror (or prism) in the design because current microscope video cameras are typically smaller than DSLR camera adapters and do not need to be offset. Additionally, the focal distance of video adapters is less than that of pho-

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Microscope Armamentarium Important for Videography Fig 3- 2 Comparison of video camera adapters and photo adapters. The size of the photo adapter is significantly larger than the video camera adapters due to the requirement of lenses with longer focal length in DSLR photography. ( left to right ) F = 45 mm video adapter (Global Surgical), F = 60 mm video adapter (Carl Zeiss) , and F = 340 mm photo adapter (Carl Zeiss).

Fig 3- 3 (a) TRIO 610 (Carl Zeiss) integrates a 3CCD 1080p HD camera and F = 50 mm video lens all in one unit, (b) F = 60/340 mm video/ photo adapter (Carl Zeiss) with a DSLR camera (Canon) and HD video camera (Sentech) allowing simultaneous video as well as still photography through one adapter.

Fig 3-4 (a ) The Zeiss pico with integrated video camera (Carl Zeiss), with the majority of video components contained within the body of the microscope. (Courtesy of Carl Zeiss.) ( b) The Leica M320 with the integrated video module (Leica Microsystems) in a completely invisible installation (ie, no video wires or camera visible). (Courtesy of Leica Microsystems.)

Video iris

the smaller size of the chips found in the video camera body. As explained in chapter 2, the smaller chips result in higher camera magnification, which equates to lower magnification required in the video adapter. Additionally, because of the variety of chip sizes available in video camera bodies, users should pay close attention to the manufacturer specifications so the appropriate video adapter focal length-chip size combination is selected. Otherwise, the video will either be too high or too low in magnification compared with what is seen through the microscope eyepieces. The most common chip sizes used in microscope video cam eras are 1/B- and 1/2-inch chips, which are best paired with video adapters in the focal distance range of 45 to 60 mm and 60 to 85 mm, respectively. Finally, as a result of the compact nature of microscope video cameras, some manufacturers offer integrated configurations where the camera is built into the microscope body or dual-adapter designs where both video and photo adapters are combined into one unit (Figs 3-3 and 3 -4). to adapters

due

to

As mentioned in chapter 2, an iris closes and opens the aperture, increasing or decreasing the depth of field as well as the amount of light the camera sees. When adding video to a microscope, the system can utilize a dual-iris diaphragm, a video adapter iris, or in some cases no iris at all. While the dual-iris diaphragm is mandatory for optimum depth of field in DSLR photography, a video iris is not always required in videography because the small size of the chips in most microscope video cameras effectively creates a decreased aperture, which inherently increases the depth of field of the video. Therefore, the video iris is an optional component in many systems. Additionally, for video systems that require an iris and are not presently using a dual-iris diaphragm, many video adapters come equipped with either a simple fixed video adapter insert or a variable integrated form (Fig 3-5).

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Setting Up Your Dental Operating Microscope for Videography Fig 3-5 ACCU-BEAM video adapter (TTII Medical) (left ) contains an adjustable iris mechanism, whereas the Zeiss F = 60 mm video adapter (right) has a removable iris insert.

Video camera

Reticle

The quality of a microscope video camera is primarily measured by the size and the number of the chips it contains. Microscope video camera chips come in many diameters, but the most common are V2 inch, 1/a inch, and 2A inch. Like DSLR camera sensors, larger chips offer less noise, improved low-light performance, and a better dynamic range, but they also require a bigger and

A reticle is a dotted circle placed in the eyepiece of the operator's dominant eye to center his or her view, and its importance cannot be overemphasized. During a typical microscope procedure, it is not unusual for a task that is well within the operator's field of view to be more toward the periphery of the eyepiece's field of view. A spectator viewing this type of procedure in real -time on a monitor will quickly recognize when a reticle is not being utilized because the center of focus may be far off from the center of the monitor. A reticle will quickly remind the operator where to keep the center of attention during the procedure and prevent development of an

higher-magnification video adapter to cast an image over them. Video cameras with smaller chips have the advantages of increased depth of field and smaller physical size, making the camera itself smaller and lighter. Consequently, microscope video camera manufacturers strive to maximize the depth of field aspect of the camera while minimizing the size and weight of the housing, which means that the best microscope cameras available have 34 inch-diameter chips. The number of chips contained in the camera also impacts video quality. Microscope video cameras are available in 1-chip (1CCD) and 3-chip (3CCD) configurations, where CCD stands for charge-coupled device. A 1CCD camera uses a single computer chip to process all the colors the camera sees, whereas the more expensive 3CCD camera processes each of the primary colors (ie, red, green, and blue) separately9 and thus produces better color rendition, higher dynamic range, higher resolution, less noise, and higher light sensitivity. Not surprisingly, 3CCD cameras are priced three to five times as much as 1CCD cameras. While there are 1CCD cameras available that can produce good video quality, 3CCD HD cameras using 34 inch-diameter chips presently offer the highest-quality video (Fig 3-6).

almost unwatchable video.

Video cables Video cables carry the video signal to the video displays and recording devices and can dramatically affect the final video quality. For example, simple, low- cost com posite video cables carry the information for video resolution, line and frame synchronization, color (ie, luminance, chrominance, hue, saturation), and even sound through just one or two wires, which requires a high degree of signal processing and limits the color depth and resolution of the video. In contrast, higher- quality digital visual interface (DVI) or high-definition multimedia interface (HDMI) cables carry the signal through a much higher bandwidth via multiple wires without the use of compression, thereby imposing no real limit on color depth and resolution. Table 3-3 lists various cable, connector, and signal quality options available for use when setting up a microscope for videography.8 Finally, many cameras offer video signal outputs in several formats (Fig 3-7), and while an inexpensive, composite standard definition (SD) video cable might function with a particular system, a DVI cable would transmit a much higher resolution and HD video output.

I

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Microscope Armamentarium Important for Videography Fig 3- 6 (a ) OPMI Vario microscope (Carl Zeiss) with Microcast HDXS Vi -inch 3CCD 1080p HD video camera (Optronics) with Quintus video

adapter (Optronics). (Courtesy of Optronics.) (b) OPMI PROErgo microscope (Carl Zeiss) with TRIO 610 /j-inch 3CCD HD video camera (Carl

Zeiss).

Table 3-3

Video cable

Various cable, connector, and signal quality options available for use when setting up a video system

Technology Analog

BND (1x) or FBAS or VBS

Good

100 m

Analog

4pin mini DIN or BNC (2 x )

Bad connection

Analog

BNC (3 x) or RCA

Analog

BNC (4x)

Composite

S-Video

Component

YPbPf

Connector mechanical quality

Connector Type

Maximum

length

Video signal quality

supported

Recommended

format

for SD

Lowest

PAL/NTSC interlaced scanning

Low

PAIVNTSC interlaced scanning

SD

10 or 20 m

100 or 10 m

Good

SD/HD: interlaced or progressive scanning

SD or HD

Good

Good

Very good

SD/HD: inter-

SD or HD

100 m

laced or progres-

Component RGB

Video signal

sive scanning

RGB-HV, VGA

Analog

BNC (5 x or HD-15 connector

Good

100 or 10 m

Very good

Good

4.5 m

Very good

[ "VGA"])

i.Link

Digital

FireWire, DV, or IEEE 1384

SD/HD: interlaced or progressive scanning

SD or HD

SD/HD: inter-

SD (HD only for HDV/FireWire)

laced or progressive scanning

DVI-D / HDMI

SD/HD: inter-

Digital

DVI-D or HDMI

Good

5-30 m

Best

laced or progressive scanning

Best

SD/HD: interlaced or progressive scanning

HD: Short cable runs, but best

quality and compatible with monitors

SDI (ie, mSDI, HD-SDI, 3G-SDI)

Digital

BNC (1x)

Good

100 m

HD: Best quality for all formats, low price, and long cable runs

HDMI, high-definition multimedia interface; SD, standard definition; HD, high definition; PAL, Phase Alternating Line; NTSC, National Television System Committee.

Fig 3- 7 The rear panel of the TRIO 610 HD video camera system (Carl Zeiss) showing the various cable connections and formats that can be used with current microscope vid-

eo cameras.

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Setting Up Your Dental Operating Microscope for Videography

Differences in monitor output

Video display The video display (commonly known as the monitor ) is the most recognizable but also perhaps the most variable of the components in the video chain. New video display technology advances are made every day, so the information provided in a book such as this is outdated almost before it is published. Nevertheless, a brief dis cussion of what specifications to look for will assist readers in choosing an appropriate model for their system. A good general rule is to choose the highest-quality display that has a resolution and refresh rate equal to or better than the camera being utilized. HD displays dominate the marketplace today, yet many microscope users may not be in a position to invest in an HD camera. Consider purchasing a display that has both HD and SD inputs. Typical brightness ratings range from 250 to 350 cd/ m2 for monitors that perform general-purpose tasks. For displaying movies, a brighter luminance rating such as 500 cd/m2 might be desirable; however, this is highly dependent on the room's ambient lighting. The size of a monitor is determined by measuring the diagonal distance from the bottom left corner to the upper right corner. A few more detailed terms relating to video display are discussed in the following sections.

Static contrast ratio The static contrast ratio is the difference between the darkest and brightest parts of an image on a monitor at the same backlight level and is easily the most important factor in overall picture quality.10 A display with a low contrast ratio will seem washed out and flat compared to one with a high contrast ratio, which will seem more realistic with greater "depth."10 A contrast ratio of 1,000:1 is considered respectable, and a ratio of 2,000:1 is stellar.11

Response time The response time, which refers to the amount of time it takes a pixel in the monitor to go from black to white and back to black, should be short in order to allow adequate real-time projection of video (ie, video streaming) during procedures with minimal to no delay. A poor response time will manifest as a moving image appearing blurry or will elicit a cometlike tail when moving across the screen. A response time of less than 10 milliseconds

Finally, when video content is viewed or compared in the dental office, differences in monitor output significantly affect what the user sees If more than one monitor is used, they should have similar specifications, or else a calibration device or software should be used to establish similar views.

.

Recording device An optional accessory in the video chain and often the least utilized, the video recorder allows the microscope operator to capture, store, and later edit video footage of clinical procedures. The video recording process must be integrated into the clinical workflow and therefore should be activated by an assistant using a remote control or via the doctor through the microscope hand- grip where possible. Many video recording systems offer a frame capture function, but even the latest HD recorders cannot yet rival the quality of typical DSLR photography. As with other video system components, attention must be given to assure that the video recorder supports the highest affordable format available at the time of purchase and that the recording quality at least equals that of the camera. Several high-end microscope video camera systems incorporate video capture, still image capture, and recording capabilities in the same device. Finally, videography requires a significant commitment in postproduction time to edit the video excerpts. For this reason, video streaming might be the most widely used medium for imaging through an operating microscope. However, video recording and editing are the least utilized documentation procedures.

Assembling Different Video Configurations There are many video configurations available for equipping a microscope to record or stream live video. When selecting which configuration is best, the operator should consider the following factors:

•Video quality desired

•Camera size desired

•Ergonomics •Desire to utilize a co-observation scope

is considered acceptable.8'11

•Desire

to have both DSLR imaging and video capabilities •Weight-bearing capacity of the microscope •Duration of output desired •Desire to stream or record video •Budget

Brightness A bright screen is important when working in a well-lit room. Brightness is expressed as candelas per square meter, or cd/m2, where the higher the number, the better

the quality of the video display.

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Assembling Different Video Configurations Fig 3- 8 (a ) Direct HD video system (TTI Medical) on a Wild microscope (Leica Microsystems), (b ) The G6 microscope (Global Surgical) with F = 45 mm video adapter and Sentech HD video camera (Sensor Technologies).

A C«IZM

I'

Fig 3- 9 OPMI PROErgo microscope equipped with a dual-iris diaphragm, angled opticsdual-port Zeiss 50 beam splitter (Carl Zeiss), co-observation system, photo adapter, DSLR camera, Zeiss 20 beam splitter (Carl Zeiss) , TRIO 610 1/3 -inch 3CCD HD video camera (Carl Zeiss), and a reticle incorporated in the dominant eye-

-

/A p

-/

side eyepiece.

These factors will influence which scenario a particular user selects. The following sections briefly discuss common setups; these setups may require adjustment as new technolog-

lens combination (see Table 3-2). Furthermore, only a select few microscope systems are able to handle the additional weight of a co-observation scope, a DSLR camera, two beam splitters, and a video camera (Fig 3-9). ter-video

ic advances are made.

Low-light beam splitter and external microscope video camera

Traditional 50/50 beam splitter and external microscope video camera

Most microscope manufacturers sell a beam splitter that delivers less light to the side port than a 50/ 50 beam splitter would, known as a low - light beam splitter (Fig 3-10). These beam splitters allow more light to continue on through the microscope to the doctor 's eyepieces and work well due to the high-sensitivity video chip cameras presently available. Although reducing the light to the camera can in some cases slightly reduce the video quality, the benefit of allowing more light to pass through the microscope to the eyepieces outweighs this small reduction in quality. When a low-light beam splitter is used, a video adapt er, video camera, video iris (system and/or adapter de pendent), video cables, and video display ( and perhaps

Today the most common and versatile method for adding videography to an operating microscope is through the addition of a dual-port 50/ 50 beam splitter (Fig 3- 8; see also Fig 3 - 6). This single component offers the most flexibility when using additional accessories such as a co- observation scope, a video camera, and/or a DSLR camera system. It also allows the greatest ease in changing components, should the user decide to change to another medium or the available technology changes or a camera fails. When this configuration is used, a video adapter, video camera, video cables, and video display (and perhaps a recording device as well) are required to complete the video chain. Also, depending on the video adapter used, an iris might be required in the form of an iris insert, video adapter variable iris, or dual-iris diaphragm ( diaphragm needs to be placed beneath the beam splitter on the microscope). All video cameras that lend themselves for use with a microscope can be used with a 50/50 beam splitter, which provides the greatest light to the camera, offers quality video, and does not limit the duration of operation. Additionally, certain microscope systems allow a 50/50 beam splitter to be used in concert with a specialized beam split-

a recording device as well) are required to complete the video chain. Some beam splitters, such as the Virtual Beamsplitter (Global Surgical) or the Seiler 50/ 50-20/ 80 ( Seiler Instrument), can also accommodate the addition of a co -observation system to the 50/ 50 side. Others, such as the Zeiss 20 beam splitter (Carl Zeiss), would not be the best choice for this application because they offer inadequate light to the assistant, which negatively affects patient treatment.

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Setting Up Your Dental Operating Microscope for Videography

c Fig 3 - 10 (a) Seiler microscope (Seiler Instrument) equipped with a 50/50-80/20 beam splitter where an F = 60 mm video adapter and Sentech /a -inch CCD HD video camera (Sensor Technologies) are mounted on the 80/20 side port. (Courtesy of Seiler Instrument.) (b) The G6 microscope with a Virtual Beamsplitter where an F = 45 mm video adapter and Sentech 1/3 -inch CCD HD video camera ( Sensor Technologies) are mounted on the virtual side port. (Courtesy of Global Surgical.) (c) Top view of the Virtual Beamsplitter where the small mirror spot on the peripheral port reflects 3.5% of the light to the camera, allowing 96.5% to pass through to the eyepieces.

Fig 3-11 (a) FlexioMotion (Carl Zeiss)-Sony Handycam combination mounted on the documentation port of a Zeiss pico with MORA interface (Carl Zeiss). (Courtesy of Carl Zeiss.) (b ) Seiler Sony Handycam adapter mount ed on a 50/50- 20/80 beam splitter (Courtesy of Seiler Instrument.)

.

Integrated video camera

Camcorder

The integrated video camera is compact and ergonom ically friendly, usually shows few to no external cables, and has the "cleanest " outside appearance of any video system (see Fig 3-4). This system is both secure and reliable, and it does not require assembly. In addition, components are always perfectly matched with the optical system of the microscope, which allows for immediate use without the need for any adjustments by the consumer. This video chain does not require an iris mecha nism or any other additional components, aside from a video display and an optional recording device. Despite these advantages, however, there can be several significant limitations to this setup. First, at the time of this writing, there are very few options that allow a user to upgrade an integrated system. Second, only 1CCD (and not 3CCD) HD integrated devices are available. Third, these integrated systems can also vary widely in price, so users should thoroughly investigate and compare products before settling on a purchase. Finally, although some systems might allow the addition of other accessories to the microscope, users must be careful not to exceed the weight -bearing capacity of the

system.

A surprisingly easy and cost-effective way to obtain both video streaming and recording output is through the addition of a Handycam camcorder (Fig 3-11). Moderate to high-end, consumer- grade video cameras can be attached to a specialized microscope video adapter (eg, Global XMount [ Global Surgical ], FlexioMotion [ Carl Zeiss ] or Seiler Handycam adapter [ Seiler Instrument]) to significantly simplify the video chain. However, these systems vary depending on the microscope and camera manufacturer. This low-cost option provides high-quality HD recordings and usually can capture still images as well; however, these camcorders are not quite at the level of a true high end microscope and can suffer slightly in their light sen sitivity and color-rendering capabilities. Additionally, the camcorder body must be attached to one side of a beam splitter, which presents challenges in terms of achieving proper ergonomics as well as supporting the additional weight of the device. Also, to complete the video chain, this setup requires a 50/ 50 or specialized beam splitter, a camcorder video adapter, video camera, and an optional external video monitor. This configuration does not require an additional iris of any type because the video camera's internal lens system already contains a camera-controlled iris.

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Conclusion Fig 3-12 OPMI PROErgo microscope equipped to capture both digital stills and 1080p video through a DSLR camera. Accessories include a dual-iris diaphragm, angled optics-dual-port Zeiss 50 beam splitter, co-observation system, photo adapter, DSLR camera, and a reticle incorporated in the dominant eye-side eyepiece.

HD video-enabled DSLR cameras

scope, 10 x eyepieces, a reticle located in the eyepiece of the operator's dominant eye, a DSLR camera capable of an HDMI output, video cables, and a video display to complete the video chain. An important modification for HD video capture, however, is the orientation of the camera: Both the photo adapter and the DSLR camera must be rotated to account for proper right -left and forwardbackward coordination between the operator's movements and the video displayed on the monitor (Fig 3-12). The camera settings for HD video-enabled DSLR camera microscopes are the same as described in chapter 2 (see Box 2-2), with the addition of the live view function. Live view is designed to display the captured video in the window monitor on the rear of the camera; once a cable is connected to the camera's HDMI output port, the video feed is transferred from the camera's monitor to the external display monitor, making these highquality cameras quite convenient.

Recent advancements in DSLR cameras have allowed the still photographer to acquire 1080p HD video excerpts with the same camera body. Consequently, most microscope DSLR camera systems include an HD video capture function and, recently, even 4K (ultra HD) video

capabilities. This configuration can capture an occasional short video clip or a limited amount of video streaming, which should accommodate the needs of most users. The video capabilities of these cameras rival the output of much more expensive, professional video cameras. However, this configuration is limited in the duration of operation, making it difficult to record procedures lasting longer than 30 minutes in one clip. The maximum recording time of one video clip through a DSLR camera is 29 minutes and 59 seconds (or a maximum of 4GB, whichever comes sooner), after which the camera will stop recording. No file larger than 4GB can be recorded with this system due to the nature of the FAT 32 partitions of the recording media. Consumer camera companies also set this time restriction so that only cameras classified as "camcorder " support longer video recording. Furthermore, when the output function of a DSLR camera is used to project the video signal to a video display, internal heat production and increased thermal noise can cause the sensor to overheat and shut down after about 50 minutes of use (depending on the manufacturer, conditions of use, camera model, and ambient room temperature). At the time of this writing, only the Sony NEX and Alpha camera lines allow video streaming for longer than 1 hour. Additionally, the video-out display with these systems is a bit more cluttered when compared with traditional microscope video camera options; however, it is still quite acceptable as a procedural

Conclusion As microscopic documentation becomes more common, the clinician will need to decide whether to capture still images, video, or both This chapter has provided a set of parameters for selecting the best configuration based on the user 's needs and desires. The majority of clinicians may find that a simple microscope setup alone or the addition of a DSLR camera and co- observation scope may suffice; however, those who teach, lecture, or want a video-enabled microscope will find the many possibilities exciting. If emerging technology is any indicator for the future, then video will most certainly have a place in microscopic documentation. Hopefully, the ease of acquisition will be improved and the time required to manipulate and edit video material will be shortened, as these aspects along with the financial investment are major limitations that need to be overcome.

.

display. The assembly for an HD video-enabled microscope using a DSLR camera is identical to the setup for capturing still images discussed in chapter 2. This assembly includes the dual-iris diaphragm for aperture control, a 50/ 50 beam splitter, a photo adapter, a co-observation

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Setting Up Your Dental Operating Microscope for Videography

References

7. DeMaio J. The Truth about Video Gain and How To Use It Properly. Production Apprentice. 31 August 2010. http:/ / www. productionapprentice. com /featured/the- truth-about video-gain- and-how-to-use-it-properly/. Accessed 19 January 2014. 8. Carl Zeiss Meditec. Video Basics. Compendium 2010;1.2:1-121. 9. Grabowicz P, Seidler E, Kaneshiro V, Reynolds P. Sony Pd 150/170 Video Cameras. KDMC Berkeley. 16 June 2011. http:/ / multimedia . journalism .berkeley. edu /tutorials / vid cams/. Accessed 30 March 2014. 10. Morrison G. LED LCD vs. OLED vs. Plasma. CNET. 18 November 2013. http:/ /www.cnet.com/news/led-lcd-vs-oledvs-plasma/. Accessed 7 April 2014. 11. Murphy K. Things to Consider When Buying a Monitor. The New York Times. 22 August 2012. http://www.nytimes. com/ 2012 /08/ 23 /technology/personaltech/things -to -con sider- when -buying- a -monitor.html ?pagewanted=all& _ r =0. Accessed 8 April 2014.

1. Kaschke O. Digital video solutions: Insight into the conscious use of modern visualization technologies. Informed 2006;2:24-27. Carl Zeiss Meditec publication. 2. Axis Communications. Resolutions, http:// www.axis.com/ products/video/about_networkvideo/resolution. Accessed 30 December 2013. 3. Apple. Final Cut Pro 7 User Manual 2010. http://documentation.apple.com/en/finalcutpro/usermanual/index.html. Accessed 30 December 2013. 4. Steve's Digicams. The Difference Between a 16:9 Aspect Ra tio and 4:3 Aspect Ratio, http:// www.steves-digicams.com/ knowledge- center /how-tos/digital- camera -operation/thedifference-between-a -169- aspect-ratio-and- 43- aspect-ratio. html. Accessed 18 January 2014. 5. Briere D, Hurley P. Home Theater for Dummies, ed 3. Hoboken, NJ: Wiley, 2009. 6. Monahan S. Video Editing Terms Explained—Part 2: Progressive (p) vs Interlaced (i) Recordings. Serif Blog. 31 August 2012. http://www.serif.com/blog/video-editing-terms-explainedpart-2-progressive-p-vs-interlaced-i-recordings/ Accessed 19 January 2014.

.

AC\

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CHAPTER

Jeffrey B. Pafford, DMD, MS Keith G . Kanter, DDS

Photodocumentation for

Why Are Photographs Needed? Photographically documenting your treatment through the dental operating microscope is an enjoyable part of practice. More importantly, it helps you explain your treatment recommendations to your patients for effective informed consent, assists you in communicating with referring dentists, and helps protect you in the event of medicolegal challenges. Photographs taken during the initial examination aid in preoperative conversations with patients about the complexity and prognosis of their treatment and help you explain your treatment recommendations (Fig 4-1). When patients can see the problem photographically, they are more comfortable with the conversation and the decision-making process. An informed patient can make decisions based on personal needs and desires. Photography helps you develop the trusting relationship needed for a mutually beneficial outcome. Digital photographs also enhance communication with other dentists. They help build stronger referral relationships in both directions and ultimately yield better decisions and results for patients. Sharp, clear photographs also provide important documentation for medicolegal purposes, espe cially when preexisting conditions are present.

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4

Photodocumentation for Endodontics

Probing Tz +mm

Fig 4- 1 Consult photograph tak- Fig 4- 2 Photograph of the pulpal Fig 4 - 3 Photograph of an uninstru- Fig 4- 4 Photograph of cracks/frac en during the initial patient exam- status upon entry in the chamber/ mented/missed canal. MB2, second tures. mesiobuccal canal. ination. canals.

Fig 4- 5 Photograph showing in- Fig 4-6 Photograph taken after Fig 4-7 Photograph taken af vasive cervical resorption. ter the definitive restoration was obturation. placed.

•Consult photographs, which may include a sinus tract,

When Should Photographs Be Taken?

defective restorations, occlusal interferences, discolored teeth, or deep periodontal probings with the probe in place (see Fig 4-1). •Preoperative photographs taken once the rubber dam is in place. (This may be important if a crown has chipped porcelain, for example.) •Photographs of the pulpal status upon entry into the chamber /canals (Fig 4-2). •Photographs of special situations: - Uninstrumented/missed canals, for retreatments (Fig 4- 3) - Separated instruments

Once the microscope and camera are properly set up (see chapter 2), cases can be documented while you are working The assistant can activate the camera with a computer mouse so that images can be captured without any interruption in treatment flow The author (JBP) takes a standard set of photographs for all cases (see below). Some cases require only a few

.

.

photographs and others many; the circumstances of the case dictate how many and what techniques are used. If the camera is connected and triggered through the computer on the clinician's side, the clinician can verify that the picture captured shows the desired effect and field.

- Perforations

- Unusual anatomy - Cracks/fractures, either coronal or radicular (Fig 4-4) - Resorption (Fig 4-5) •Photographs of the canals after cleaning and shaping. •Photographs taken after obturation (Fig 4-6). •Photographs taken after the definitive restoration has been placed (Fig 4-7). •Any other photographs of interest.

Standard Photographic Set for Nonsurgical Endodontics The types of photographs listed below are recommended for routine documentation of every case:

High-quality photographs require a highly reflective mirror, such as those sold by Excellence in Endodontics 2 or Zirc.

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Standard Photographic Set for Nonsurgical Endodontics

( ) Fig 4-8 [a ) Maxillary left second molar that appears to require routine nonsurgical treatment, (b) Only one mesiobuccal second ,( ) orifice could be found upon entry. A digital photograph was taken to aid the endodontist for the second visit c At the appointment, a second, negotiable MB canal was located, (d) Final radiograph.

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Fig 4- 9 (a) Preoperative radiograph of the mandibular right first molar, (b) Preoperative photograph taken after the rubber dam was placed, (c) Pulpal status photograph showing the necrotic pulp, (d) Working photograph showing leakage under the original composite restoration, (e) Working photograph taken prior to a pre-endodontic buildup, (f ) Working photograph showing the pre-endodontic buildup, (g) Photograph taken prior to obturation (often taken to document any unusual findings or anatomy). DL, distolingual canal; radix, radix entomolaris; MidD, middle distal canal; DB, distobuccal canal, (h) Post-obturation photograph, (i) Definitive restoration. ( j ) Final radiograph.

explore further when the patient returned 1 month later. Ultimately, a second, negotiable MB canal (MB2) was located (Fig 4- 8c), and the case was completed with this separate MB2 canal splitting off the main MB canal (Fig 4- 8d). The photograph documenting endodontic treatment of the mandibular right first molar (Fig 4-9a), taken during treatment, is a typical example and required little additional effort. As noted above, every case will warrant a different set of photographs as dictated by the situation and the patient. As this case progressed, the changing circumstances were documented with digital photographs. These photographs show standard and unusual circumstances or items of interest to the patient or referring dentist. Figures 4-9b to 4-9j document endodontic treatment of the mandibular right first molar.

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Case report Teeth can appear to have straightforward anatomy preoperatively, but that impression sometimes changes once the canal system is entered, as this case shows. The maxillary left second molar would appear to require routine nonsurgical treatment (Fig 4- 8a). Upon entry, however, only one mesiobuccal (MB) orifice could be found. Pre-bent handfiles were introduced and produced a " stick " on the palatal side of the MB canal. The MB canal was then lightly troughed with ultrasonics, and a mesiolingual fin was visualized, but a point of negotiation could not be located. As the initial appointment was coming to a close, a digital photograph was taken to aid the author at the second visit (Fig 4-8b). Notes were added to the photograph, reminding the author

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4 Photodocumentation for Endodontics

Jeffrey B. Pafford, D.M.D., M.S. Specialist in Endodontics

755 Commerce Drive, Suite 916 Decatur, GA 30030

PAFFORD ENDODONTICS

( 404) 377-9395

www.paffordendo. com

July 31 , 2012

Referring Dental Office 123 Peachtree Street Atlanta , GA Dear Referring Dentist: Endodontic treatment on President Thomas Jefferson was completed on 7/31/2012 for tooth #30 . President Jefferson will be returning to your office for continued care. Should you wish to discuss this case further, please do not hesitate to call. Periapical Diagnosis: APP Restorative Recommendations: Crown

Pulpal Diagnosis: Necrotic Pulp Prognosis: Good i.

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You may access treatment status , medications prescribed , future appointments , images and radiographs for all of your patients by visiting www.Daffordendo.com . Please contact our office for your login information.

Thank you for your confidence in referring this patient and for the opportunity to be a part of your dental team. Please let us know if we can be of further assistance on this or any other of your cases. Sincerely ,

Jeffrey B. Pafford , D.M.D., M.S. Fig 4- 10 An example of a final report to a referring doctor.

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Fig 4-11 Photographic set for surgical endodontics, (a) Preoperative radiograph. (b) Preoperative clinical photograph, (c) Sulcular depths are measured, (d ) Initial incision, (e) Flap reflected, (f) Root-end resection and crypt control, (g ) Retrofilling in place, (h) Flap repositioned and sutured, ( i ) Postoperative radiograph, ( j ) Suture

removal.

5. Root resection and crypt development (Fig 4-1If) 6. Retrofilling (Fig 4-11g) 7. Sutures (Fig 4-11h and 4-11i) 8. Suture removal (Fig 4-11 j)

Figure 4-10 is an example of a final report to a referring doctor. It includes written information and radio graphic and photographic documentation of treatment.

Other findings are documented as necessary, and they may include cracks, sinus exposures, and the neurovascular bundle, among others.

Standard Photographic Set for Surgical Endodontics Endodontic surgery has become less common in recent years as retreatment procedures have become more

Conclusion

predictable and implants have gained popularity. However, there are still clinical scenarios where endodontic surgery is the treatment of choice. The author (KGK) documents at least eight steps of the surgical process with photographs:

Successful practitioners are able to evoke confidence and trust from their patients, and photographs are a powerful tool in the development of positive patient relationships. Because most people are visual learners, photography helps simplify patient conversations and leads to better understanding. Effective communication between treating doctors is also very important in build ing confidence in patients. Finally, photography makes you look high-tech /' something most patients and other doctors associate with competence and intelligenee.

1. Preoperative view including at least three teeth and the surrounding gingiva (Fig 4-11a and 4-11b) 2. Periodontal probing (Fig 4-11c) 3. Incision (Fig 4-11d) 4. Flap elevation ( Fig 4-11e)

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CHAPTER

Michael Trudeau, DDS

Training an Assistant to Work Under an Operating

Developing highly competent team members is one of the primary keys to a successful and enjoyable endodontic practice. There is no substitute for having a well-trained assistant (Fig 5-1) who can efficiently and skillfully manage challenging endodontic and restorative procedures under the operating microscope. As endodontic treatment and case referrals become more challenging from both technical and behavioral perspectives; successful and rewarding management of these cases demands exceptional individuals working as a team. A team that shares a common purpose and demonstrates a unified vision and commitment to providing outstanding care is recognizable by patients, clinicians, and referral sources alike. The skills and vision that inform this team approach must be acquired over time and represent an investment that every clinician must make to excel in this area. It is axiomatic that any team can only be as good as its weakest member. This chapter reviews many of the steps the author has found helpful in training assistants in microscopic endodontics. If these steps are followed, it is possible to train a motivated assistant within a 3-month period. Such training will benefit a practice for many years into the future, making the investment in time and energy one of the best investments a clinician can make in his or her career.

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Building a Basic Skill Set

Fig 5-1 A chairside assistant looks through the Fig 5-2 (a ) The assistant releases the clutch and adjusts the co-observation tube (b) The coco-observation tube to actively participate in the observation tube allows three axes of movements of the arm so the assistant can be positioned comfortably. treatment. ,

der the microscope: positioning of materials, instruments, and the microscope; positioning of the patient, doctor, and assistant; and the practice of effective ergonomics (ie, work limited primarily to Class I and Class II motions).

Overview of the Training Process There are three major goals that must be set for any kind of training to be effective:

Building a Basic Skill Set

1. Establish the vision and endpoint goals clearly and without equivocation. 2. Figure out the details and the methods to be used to attain and master those details. 3. Have a time frame established that outlines attainable and realistic objectives and how they will be

The most effective way to train an assistant is through basic skill set building, which is the same process a child follows when learning to play a piano (eg, practicing with repetition, learning one song before moving on to the next, etc). At the beginning of each session, the clinician and the assistant should revisit skills that were taught in previous sessions, typically in the same order they were introduced. If competency in a newly taught skill is not established within a reasonable period, the clinician should conduct an additional training session devoted to that skill before moving on to a new one. The basic skill set for an endodontic assistant consists of the following: positioning the microscope, reading hand signals, swapping mirrors, transferring files, delivering anesthetic, bending files, transferring rotary files, and irrigating canals. Each of these skills is described in detail below. The ultimate goal of training is to incorporate these basic skills into muscle memory so that the assistant does not have to think about the actions as they are being performed.

measured.

The assistant must first and foremost understand the vision of how a microscopic team functions at a high level. After that vision is understood, it is only the details that need to be mastered. Often clinicians fail to adequately convey with sufficient clarity what endpoint is desired as the goal of the training. Without this endpoint, the assistant will have trouble maintaining the necessary focus to master the many small details required for competence. Another mistake that is commonly made is to assume such training can occur on the fly without a structured process. The author therefore outlines a defined, structured, disciplined process that relies on incremental skill development, repetition, muscle memory development, and reinforcement through development of reflex motion and habit. Dedicated time should be devoted to one- on -one training with the assistant without a patient being present. Development of muscle memory takes time, repetition, recalibration, and reinforcement, and this cannot occur in a patient-centered setting. Habit development is a recapitulation-type process where manual and eye skills are practiced over and over again until cognitive effort is not required. The clinician and the assistant should therefore schedule hands-on training time away from patients, whether before or after work, at lunch, or during canceled patient appointment times. The objective of hands-on training should be the seamless "choreography " of vital tasks performed un-

Positioning the microscope Before any clinical activity begins, the doctor reclines the patient, adjusts his or her own chair, positions the doctorside cart, and positions the microscope. Ideally, once positioned, the microscope is not moved (see chapter 1); instead, the patient chair is released so that it is freely movable. The doctor then instructs the assistant to adjust the co-observation tube for clear vision and comfort. The assistant releases the clutch on the co-observation tube and adjusts the three-point access, vertical range, and intraocular distance. This process should be practiced multiple times during each training session (Fig 5-2).

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5 Training an Assistant to Work Under an Operating Microscope

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Fig 5- 3 Hand signals, (a ) Patient eye protection, (b) Bite block, (c) Rubber dam (d) Anesthetic, (e) File, (f ) Irrigation, ( g ) Mirror.

Fig 5 - 4 Mirror swapping, (a) When the assistant determines a clean mirror is needed, he she or

lightly taps the doctor ’s hand, indicating that a mirror swap is coming, (b) Using the little finger, the assistant grabs the dirty mirror and swaps it for a clean one. (c) The mirror swap is completed , leaving the new mirror face in the same place as the old.

Reading hand signals

Swapping mirrors

Every skill set should be initiated with a hand signal. The signals themselves do not really matter as long as the clinician uses the same signals with all assistants. Basic skill sets that require hand signals include placement of patient eye protection, bite block, and rubber dam; delivery of anesthetic and irrigation; and transfer of files and mirrors (Fig 5 - 3). Before proceeding with training, make sure your assistant can perform basic endodontic tasks when asked to do so by a hand signal. As the assistant becomes more knowledgeable about the procedures, little, if any, verbal instruction s are necessary.

Because every tooth should be treated under the microscope from start to finish, having a clear view via a clean mirror is imperative. The assistant must be able to replace a dirty mirror with a clean one in such a way that the flow of treatment is not disrupted. For example, the clinician should be able to continue cutting with a dental handpiece during the mirror swap. Spending 1 hour passing the mirror 300 to 400 times, in both the maxillary and mandibular orientation, is a good start when conductin g training for this skill. The clinician should look through the microscope and give constant feedback to the assistant regarding the spatial position of the mirror (Fig 5- 4)

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Building a Basic Skill Set

Fig 5- 5 File transfer, (a ) The endo ring is shown loaded with files. Note the sides of the sponge. (b ) Fig 5- 6 Anesthetic delivery. The anesthetic sy The file is offered to the doctor from the east side of the sponge, (c) After the file is used, it is aimed ringe is passed to the clinician, at the assistant ’s shoulder for transfer, (d ) The file is passed back to the assistant using the south side of the sponge.

ticed initially with the needle capped to allow the assistant to become familiar with the direction of the needle and be able to pass the syringe in such a way that the clinician's finger-holds are unencumbered. Clear actions are essential; the movements must be clean and decisive. Once the technique is learned, the procedure should be practiced many more times with the needle uncapped (Fig 5 -6). Eventually, the assistant must also master the process of changing carpules and the one -handed scoop technique for safely recapping the needle.

Transferring files To maximize efficiency, the assistant should perform file

bending and measurement tasks for the clinician. The assistant wears the endo ring and manages the files, and the doctor discards used files into a plastic cup on the doctor-side cart. Passing of files starts with the assistant placing a file on the east side of the endo ring sponge (Fig 5 -5 a). The file is brought into the waiting fingers of the doctor (Fig 5 - 5b). The assistant then anticipates the next file needed by the doctor and places it again in the east side of the sponge. When the clinician is ready to swap files, he or she points the file tip at the assistant's left shoulder (Fig 5 - 5 c). The assistant receives it with the south side of the sponge (Fig 5 - 5d), makes a onequarter counterclockwise turn, and from the east side brings the new file into the waiting fingers of the clinician. Using a series of files (eg, nos. 8 to 20 K), the assistant and the clinician should practice transferring files. After a few hours of practice, the process will quickly be committed to muscle memory for both the clinician and the assistant.

Bending files Accomplishing the specific bends needed by the clinician is a skill the assistant should develop over time, using tools such as cotton forceps, cuticle scissors, and the Buchanan Endo - Bender (SybronEndo), among others (Fig 5 -7). The clinician should demonstrate, under the microscope, the different types of bends that are required, assigning each one an appropriate name. Using a sponge of 60 to 100 K-files (nos. 8 and 10 are the author's preference), the assistant should practice making the most common bend and then passing the file to the clinician. The clinician should evaluate the bend under the microscope and provide feedback. Over time, as the assistant masters the first bend, multiple bends can be incorporated into the training.

Delivering anesthetic Delivering anesthetic under the microscope is not only more efficient and ergonomic, but it also contributes to overall patient comfort. Passing of the syringe is prac -

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5 Training an Assistant to Work Under an Operating Microscope

Fig 5-7 File bending. File bending using cotton forceps (a), cuticle scissors (b), and the Buchanan Endo-Bender (c).

Fig 5-8 Rotary transfer, (a ) The clinician operates the rotary handpiece, (b) The assistant swaps the hypochlorite syringe for the rotary handpiece, (c) The clinician irrigates, (d ) The assistant swaps the hypochlorite syringe for a hand file. While the clinician hand-files, the assistant changes the rotary file, (e ) The assistant swaps the hand file for the rotary handpiece, (f ) The doctor again operates the rotary handpiece.

Transferring rotary files and irrigating canals

2. The rotary cutting instrument is located on the back wall. (A cordless handpiece would be handled the same way.)

The ergonomics of rotary file transfer and irrigation depend on the dental operatory layout. There are two common configurations:

The assistant must be able to swap a rotary (or cordless) handpiece for irrigation and then suction ; a rightangled suction is most helpful in this action. The benefit here is that the clinician can hand-file while the rotary file is swapped and measured by the assistant ( Fig 5 - 8).

I. The rotary cutting instrument is incorporated into

the doctor-side cart.

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Summary Fig 5 - 9 Stropko Irrigator, (a and b ) While looking through the co-observation tube, the assistant clears debris from the tooth, cleans the mirror, and anticipates the doctor ’s next move.

Advanced Skill Sets

tice working with extracted teeth so the assistant is not disoriented when taking the new skills to the patient. Doing a few access preparations on extracted teeth will help the assistant become familiar with the tools used to keep the operative field clean. Eventually, the time comes when the assistant is ready for patient care. Schedule extra time and perhaps extra appointments—to accommodate this learning process. Remember, there will be many firsts and a multitude of mistakes, but work to encourage incremental improvement with your assistant. Nitpicking about everything at once can be detrimental to the progress of your assistant's training and professional development.

Additional, advanced skill sets will require much more practice in order for the assistant to gain proficiency. Eventually, the assistant should be able to use the Stropko Irrigator (SybronEndo) to clean the mirror and clear debris from the tooth (Fig 5 -9). This skill requires the assistant to be able to step away from a mirror—and often out of the microscope field—in order to clean the mirror. To establish proficiency usually takes many hours, much like learning a difficult dance. Use of the Stropko Irrigator is a skill that can be transferred to other advanced clinical procedures, such as maintaining a clear working field while removing obstructions from a canal or while providing surgical suction during apical surgery. It is highly desirable for the assistant to enter treatment data such as pulpal status, working lengths, and treatment notes into an assistant-side computer during treatment. Working this into the choreography requires a smart, organized assistant. Other advanced skills that are performed most effectively with the assistant "in the microscope" include removal of obstructions from canals, repair of perforations, and many restorative procedures, especially the difficult ones with isolation issues. Some clinicians place the rubber dam under the microscope.

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Summary Training an assistant to work under a microscope and effectively utilize a co-observation tube is not a simple task that will be accomplished within a few sessions. It requires purposeful practice as well as patience and persistence from both the clinician and the assistant. The goal is to learn skills in a stepwise manner and focus on continuous improvement. While the rewards of training are great for both the clinician and the assistant, it is important to implement training that will ultimately lead to improved patient care. This chapter is not intended to provide comprehensive assistant training but rather a primer of the basics. Once the basics are learned, the process gets easier. Because no two clinician- assistant teams operate exactly the same, many of the details discussed in this chapter may need to be adjusted.

Transitioning into Clinical Practice It takes time to learn how to work under a microscope. After the basic skills are mastered, it is important to prac51

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Cone Beam Computed

PART II

Tomography and Endodontics

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CHAPTER

Gary B. Carr, DDS

John Khademi, DDS, MS Richard Schwartz, DDS

Incorporating CBCT Imaging into Endodontics

Cone beam computed tomography (CBCT) imaging has experienced rapid adoption in endodontics. As with any new technology, some early adopters have made exaggerated claims about its usefulness and efficacy, which has only added to the drumbeat of its purported necessity and forced many clinicians to wonder how endodontic practice could have ever survived without it. Therefore, a judicious and sober assessment of its role in clinical endodontics is required. Although endodontists bring many strengths to the process of interpreting CBCT volumes because of our assumed domain expertise in two-dimensional (2D) radiography, competent interpretation of CBCT images is neither easy nor straightforward. Our expertise in 2D interpretation may actually be a hindrance because we express a confidence in our interpretive acumen when none is warranted. The perceptual, cognitive, and decision-making issues involved in maximizing the use of this instrument are complex, requiring much study and reflection. Most of these issues actually are not specific to three- dimensional (3D) imaging, as they have not been studied with any degree of sophistication even in 2D imaging. These issues are discussed in fuller detail in A CBCT Primer .1

The Medical Model of CT Imaging In advanced imaging modalities such as medical CT, the immediate caregiver is almost never directly involved with the acquisition or interpretation of the images. Advanced imaging studies are generally ordered by the immediate caregiver, taken by a technologist, and interpreted by a radiologist.2-4 Due to the high cost of the equipment and the specialized technologists required to obtain multipla nar cross-sectional images like CT or magnetic resonance imaging (MRI) studies, this kind of imaging is almost always done in hospital settings or at centralized imaging centers specifically designed

for such referral-based imaging. Definitive interpretation of the imaging study is performed almost exclusively by radiologists, all of whom have at least 4 years of training after medical school and many of whom are subspecialized in very specific areas of expertise, even within the domain of CT

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Incorporating CBCT Imaging into Endodontics community to

no one in the medical or dental radiology refer patients to for imaging studies in the

imaging. The outcome of the imaging study is generally in the form of an actionable report back to the ordering

endodontic

formal domain; presumably, endodontists who obtain gap this fill eventually training in radiology will L _ not a Therefore, endodontic CBCT imaging is ; it is a activity based hospital-based or imaging centerIn this . activity local private-practice, point- of -service, even from regard, endodontic CBCT imaging is different can which , implant-based or periodontal-based imaging be based on the imaging- center, order-image-report model. In endodontics, specialized technologists are More imnot taking these images endodontists are. be renot should and not portantly, endodontists are interpretation primary the lying on oral radiologists for of imaging studies unless a non- endodontic pathosis is suspected and an overread is requested. Instead, they are interpreting the findings and writing the reports themselves. Thus, while the endodontic model appears to have some benefits over the medical model, there are some issues that require careful consideration. 10,11 In their two-part review article, Miracle and Mukherji express concerns about the increasing use of a point-ofservice model of dentomaxillofacial imaging with CBCT, citing concerns with appropriateness, outcomes, and lack of training and expertise by the prescribing and interpreting clinician. They point out that CBCT has been largely adopted as an office-based service in maxillofacial imaging in dentistry. However, the technology is limited by lack of user experience and a relatively small body of related literature. In these office-based practices, CBCT imaging is usually performed and interpreted by nonradiologists who do not have the accreditation, training, or licensure required by the radiology community. Despite the risks with this newer model of CBCT imaging, there are also many advantages. The process is far less fragmented and potentially far less costly. And it is immediate: In most cases, the patient receives the results of the study right after it is taken, with the endodontist reviewing and interpreting the findings with the patient. The authors anticipate that this endodontic model will persist well into the

-

clinician.2 4

The technologists who perform the imaging and the radiologists who interpret the study usually have no direct relationship with the patient. They may have only partial information about the patient's clinical condition, symp toms, history, provisional diagnosis, or other testing findings. The medical model is therefore a somewhat fragmented, transactional process with many steps, players, and interdependencies at work. The immediate caregiver expects to read a report from the radiologist and may not even have access to the study itself or perhaps only a few sections or slices from the entire study. This model in which there is a marked division of labor and responsibilities among various professionals has served the medical community fairly well for over 30 years, and most patients receive a high degree of competence in the evaluation of their imaging. However, this model is beginning to come under pressure to deliver increased value.2,4-6 Unlike the medical model, in the practice of endodontics, the endodontist is, and is expected to be, both the radiologist and the caregiver /surgeon. There is no division of labor or responsibilities; it all lies with the endodontist. This reality has several implications for the clinician in both private and academic practice. We should consider these implications carefully, both as individual private practitioners and collectively as a specialty, especially in our postgraduate teaching institutions. This chapter outlines the many reasons why the medical model of imaging may not be appropriate for the practice of endodontics.

*

—

The Endodontic Model of CBCT Imaging Several factors have converged in endodontics to create a model different from the medical model for CT imaging. First, there has been a dramatic reduction in radiation exposure for dental CBCT imaging, especially with small and focused-field of view (FOV) imagers. This lowers the risk -benefit ratio for prescribing imaging based on ALARA (as low as reasonably achievable) guidelines as compared with medical CT imaging. Second, the dramatic decrease in cost of the imager makes these devices easily within the reach of many endodontists. This allows deployment in the endodontic practice as opposed to the leverage required to support referral to an imaging center. Third, because the technology is so new, there is a lack of domain expertise of formally trained oral radiologists in the endodontic imaging domain. It is also unlikely that formally trained radiologists will gain this expertise, as there is some evidence that perceptual learning is impaired or does not occur without feedback.7-9 This means that there is currently

future; as the technology becomes more generally accepted and used, and as the dose of exposure to the patient is reduced, clinicians will find that intraappointment CBCT studies (ie, the ability to take a study midtreatment) is one of the great advantages of having an in -house CBCT imager. Figures 6-1 to 6-4 show examples of the benefits of intra-appointment treatment imaging. Another consideration favoring the private-practice, in- office model is that endodontic practice is moving toward minimally invasive treatment, and incorporation of CBCT technology is becoming central to this CT- guided treatment approach (Fig 6- 5). CBCT-guided treatment affords the clinician the opportunity to minimize loss of key pericervical dentin while confirming that key points of negotiation of the canal systems are not overlooked. These minimally in-

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The Endodontic Model of CBCT Imaging

Fig 6 - 1 (a and b ) A conservative, stepped access was made through an all-porcelain crown. Two points of negotiation were located in the mesiobuccal root. Interoperative CBCT imaging with calcium hydroxide in the canals demonstrates balance and symmetry within the mesiobuccal root form, suggesting that there are no additional canals. Note that the bowling-pin root form dramatically reduces in the mesiodistal width as the reconstruction progresses from a slice in the coronal one-third (c) to the midroot (d ). Because of the risk of strip perforation, the second mesiobuccal canal was prepared only to a size 17/0.04 , with a maximum flute diameter of 0.65 mm.

Fig 6- 2 (a to c) A case similar to Fig 6- 1 with a conservative access but three points of negotiation in the bowling-pin root form of the mesiobuccal root, (d ) Imaging with calcium hydroxide shows the second mesiobuccal canal (MB2) coursing from the mesiobuccal orifice and joining the third mesiobuccal canal (MB3). Axial slices show thin furcation- side walls in the MB2/MB3 area even with very small (17/0.04) shapes.

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6

Incorporating CBCT Imaging into Endodontics

Fig 6- 3 (a) A periapical radiograph suggests a typical mandibular molar with two mesial canals. A conservative, stepped access was made, and one distal and two mesial points of negotiation were located, (b) At the first visit , small shapes ( / 17 0.04) were prepared, and calcium hydroxide was placed, (c ) However, interoperative CBCT imaging showed a marked lingual inclination and suggested missed mesiobuccal and distobuccal canals. These were easily located at the second visit. The initial small shaping proved to be highly fortuitous and probably avoided a strip perforation in the middle mesial canal, which was initially mistaken as the mesiobuccal canal.

to c) Initial instrumentation of a mandib ular first premolar seemed to indicate that the lingual and distobuccal canals had been entered (circle), (d) An intra-appointment CBCT with calcium hydroxide in the canals reveals an untreated mesiolingual canal (arrow ), which is mesial and lingual to the already locat ed canals, (e) CBCT imaging allowed all the canals to be treated with minimal additional removal of dentin.

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Physical Layout

Fig 6-5 CBCT can be very helpful for making orifice-directed access, as described in chapter 7. For example, measurements from CBCT slices (a to c) can guide the clinician in making precise , conservative access to the canals (d to g ), with minimal dentin removal. (Courtesy of Dr Charles Maupin, Lubbock, Texas.)

familiar with dental CBCT imagers are highly advised before installation. All CBCT imagers require thoughtful design of the walls, electrical requirements, networking requirements, lighting, ingress and egress passageways, and spacing. Lead-lined drywall may be required. Imagers are very sensitive to wall and floor vibrations, so proper structural support is essential. CBCT imagers also require a stabilized and regulated power source that carefully controls voltage and current supplied to the units within very narrow limits. Voltage and current variations or power surges can easily destroy the sensitive circuit boards within these instruments. In planning the physical space, one should consider that the acquisition and preliminary interpretation of the imaging studies should be performed in very close proximity to where the clinical procedures are performed. For this reason, it is not advised to share a facility with other specialties—a model that is commonly recommended for multispecialty practices. Having the imager in a distant part of the building or on a different floor defeats the purpose of the practice- based imaging model, which the authors believe best fits the practice of endodontics. Although a shared facility in a group-

Physical Layout

tor

Imager requirements If building from the ground up, planning for the CBCT imager space is straightforward but requires thoughtful design. There are federal, state, and local regulations for the use of radiologic devices and the shielding and spacing necessary for their use. Additionally, there may be regulations that limit who can take a study and who is required to review it. In many countries, such regulations are very stringent and serve as a significant impediment to the placement and use of such devices in a private-practice setting. Some states require filing of a Certificate of Need or other such documentation for purchase of a dental CBCT imager. Every clinician, contractor, and space planner should be familiar with all pertinent regulations before a formal design is submit ted or committed to action. The clinician is advised to carefully review state law regarding shielding and local construction code, as there is considerable variation in 15 requirements among states.12- A set of detailed plans as well as a site inspection by a state -approved inspec -

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m Incorporating CBCT Imaging into Endodontics Fig 6-7 Mirrored dual panels. The initial protocol setup may be performed by the technologist on the main panel, as shown in the foreground, or on the mirrored panel shown in the background.

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practice setting may seem to make economic sense and be attractive in theory, in practice, our experience has been that clinicians who operate this way almost always regret it. The need for a CBCT study is often unplanned and immediate. For example, when anatomical informa tion is being gathered for guidance during treatment when canals cannot be located, or when the depth and direction of bur penetration are being determined in anatomically complex cases, the need for the study is immediate and usually unanticipated. If the imager is not immediately available due to the demands of other clinicians, a great deal of frustration can be encountered. Therefore, the CBCT room should be in very close prox imity to the clinical treatment rooms. Although many CBCT imagers can be used with the patient in a standing position, most clinicians soon discover that better reconstructions are obtained with the patient seated in the gantry. Even a small amount of patient movement during image acquisition can ruin a study. Seating the patient in a chair and then moving them into proper position requires more room around the imager than that necessary for a static standing position. This extra space should be planned for when positioning the location of the imager in the room. As Fig 6-6 shows, additional space is required for the technologist to set technique parameters for the area to be surveyed. The use of mirrored dual panels for the CBCT acquisition computer may facilitate adjustment of the technique parameters for systems that use software control of the protocol (Fig 6-7). The initial protocol setup may be performed by the technologist on the main panel or on the mirrored panel. Retrofits to smaller spaces may make use of a wall to support the technologist as he or she adjusts the technique for a seated patient (Fig 6- 8 a). Small countertops nearby should be available to hold the patient's jewelry, hearing aids, hairpins, glasses, removable dental prostheses, or any other metallic objects in the imaging plane as well as a glove dispenser and a second mouse

for the technologist to adjust the technique. This second mouse is within the circle of influence of the technologist for adjusting the scan range, gantry height, center of rotation, and other technique parameters while

viewing the effects of the adjustments on the alignment beams of the imager (Fig 6-8b).

Reading room It is advantageous for the viewing and interpretation of the study to take place in the same space as the imaging itself. A preliminary read may be rendered for the purpose of immediate patient education or case presentation, for ensuring that the study has the de sired characteristics, or for directing immediate patient management where a read is required in the course of treatment.5 The room should also be designed to perform the final read, which can be a lengthier process and requires ideal viewing conditions. There is substantial research on optimal viewing conditions for reading medical CT studies that shows that the environment in which they are read affects the frequency of errors made in interpretation.16 The ambient room light needs to be controlled because it affects perception and can significantly degrade the detection of low -contrast objects; the authors recommend a moderately darkened room with no more than 50 to 80 lux.17 Although the study can be reviewed chairside for the preliminary read, most endodontists find the acquisition room far preferable for both the preliminary and final reads as well as for generating the report. It is more private, the lighting is better controlled, and the monitors can be larger and angled advantageously for presentation. In addition, the acquisition computer fre quently has better graphics capability and processing power than the operatory computer, which decreases rendering time. The acquisition room can be designed with enough space to allow seating of spouses or fam-

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Physical Layout Fig 6- 8 (a) Smaller spaces may make use of a wall to support the technologist as he or she adjusts the technique for a seated patient. The countertop in the foreground has a depression to help hold the patient ’s jewelry, hearing aids, hairpins, glasses, removable dental prostheses, or any other metallic objects in the imaging plane. The countertop in the background (behind the technologist ' s right arm) holds a glove dispenser as well as a second mouse for the technologist to adjust the technique, (b) This second mouse (arrow ) is within the circle of influence of the technologist for adjusting the scan range, gantry height, center of rotation, and other technique parameters while viewing the effects of the adjustments on the alignment beams of the imager.

Fig 6-9 (a and b) Ergonomic placement of monitors and comfortable seating in two different offices. Note that the digital record is on one screen and the CBCT reconstruction is on the other.

ily members who have an interest in the treatment and would benefit from seeing the study review. Performing an operatory presentation of the study is more ergonomically difficult in those situations. The private-practice imaging model the authors rec ommend means that the patient does not need to wait for a radiologist's overread and report. Instead, the protocol is to review the study with the patient immediately after acquisition and reconstruction, whenever possible. Immediate feedback benefits both the patient and the clinician. Going through the study with the patient reinforces the thoroughness of the consultation process, helps explain the rationale for any treatment suggested, and allows the clinician an opportunity to better explain any complexities of the case that are difficult to communicate verbally. Patients are engaged with this process, questions are better addressed, and potential misunderstandings are mitigated because patients gain a better understanding of the particulars of their case. The dual-monitor approach allows simultaneous presentation of both the reconstruction (on one monitor) and the traditional periapical radiographs or clinical photo -

graphs (on the other monitor), allowing for a very efficient case presentation (Fig 6-9).

Computers and IT Large, bright, high-resolution monitors should be rergonomically placed, and because the interpretation of the study takes time and effort, comfortable seating should be available. Studies show that the visual task of reading CBCT reconstructions taxes the vision, cognition, and posture of clinicians in ways that are difficult to assess but that can dramatically affect diagnostic performance, so these issues are not minor.17-19 Dual, large -screen, high-resolution monitors placed at eye level are advised. Currently, consumer-grade monitors are used. Medicalquality high-resolution monitors are not required, but as their prices continue to decrease, the authors anticipate that their use will become more common in endodontics. Consumer monitors coupled with consumer display adapt ers generally cannot display more than 256 shades of simulated gray (8bit), whereas true grayscale medical momtors can display 4,096 (12bit) shades, meaning that more

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Incorporating CBCT Imaging into Endodontics Fig 6-10 CBCT study on a 27 -inch Apple iMac operatory computer. Reviewing the study in the operatory, although possible, is less efficient and not as ergo nomic as having a dedicated room for viewing and presenting the case.

detail can be discerned. However, Barten20 has shown that the human visual system cannot discern more than 1,000 shades of gray and even less than that at any given level of adaptation. Furthermore, coupled with the high luminance of consumer panels, the displaying of more shades may not be beneficial.17-21 Nevertheless, when selecting among consumer-grade monitors, opt for the highest luminance and contrast ratio available. An additional consideration is size of the monitor, because side-by-side viewing may be desired to evaluate the effects of treatment or monitor potential degenerative changes. The authors find that 27inch screens are large enough for this purpose. At the time of this writing, Apple iMacs are a great choice because of their large, bright, high-resolution screens with sleek, elegant form factors (Fig 6-10).

million possible orthogonal reconstructed slices. Adding in potential curved and oblique slices, the number of reconstructable slices is essentially infinite! Endodontists are used to viewing full mouth series that usually contain 18 images at most. So the first reaction is to be overwhelmed with all the potential views, or simply to restrict the focus to the tooth or teeth that prompted the imaging. Without a defined, structured protocol for reviewing the study, endodontists can waste a lot of time and energy and are likely to make many errors in interpretation. It is the authors' opinion that the 3D rendering view contributes very little of value and, more often than not, is misleading. It can be useful in explaining volu metric imaging to the patient and explaining the dif -

ferent planes that will be examined, but after that brief explanation to the patient, the 3D rendering is better left turned off. Using the 3D rendering for diagnostic purposes guarantees that significant errors will be made in interpretation. The Carestream documentation wisely suggests that the rendered 3D volume not be used for definitive diagnosis.27 Recognizing that satisfaction of search (SoS) errors are likely to be common in CBCT image interpretation, the careful clinician will take steps to avoid such errors. Satisfaction of search was first described by Tudden ham28 in 1962, and the term was coined by Smith29 in 1967. It is commonly misunderstood to refer to the discontinuation of a search for abnormalities once a first abnormality is detected. The actual definition has more to do with expectation and a quest for meaning. Once a meaningful interpretation of the study is found, the clinician is unlikely to look for or find other interpretations. For this reason, the authors feel it is best to initially avoid focusing on the area where you are expecting to find abnormalities and instead try to get a global view of the study. As Berbaum et al write, " The phenomenon is real: Observers do not report unexpec ted findings on images when they have found something suggested by the original search task.» 30 Thus, the study should be screened first. After the ex amination is performed and the study is loaded, the patient should be seated next to the doctor and the study

Reviewing the study As discussed in A CBCT Primer,1 there is a general lack of domain expertise in interpreting endodontic CBCT studies. Until such domain expertise is acquired, endodontists will have to rely upon a scanning strategy to detect image perturbations during the interpretive processes. This is a much slower process than global recognition and also much more prone to error. Multiple studies have conclusively demonstrated that true experts perceive the essence of a scene within the first few seconds of observation—far too short of a time for a scanning strategy to

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account for their expertise 1 1622-26 This section assumes that the reader

does not have domain expertise and will be using a scanning strategy in evaluating the study, without the benefit of a large repertoire of normal and abnormal schemas stored in long-term memory. Thus, this section introduces a strategy of how to go about interpreting a CBCT study, presenting one possible protocol used by the authors to review a CBCT study based on what medicine has learned about the interpretive process.16 This strategy is discussed in more detail in A CBCT Primer.1 The first obstacle an endodontist faces in interpreting a CBCT study is the vast number of potential slices that can be viewed. A Carestream 9000 study contains 695 X 695 X 478 total pixels, which results in about 200

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Fig 6-11 The clinician is often tempted to first investigate the tooth in question. However, this practice should be avoided whenever possible because it is likely to increase SoS errors , (a ) The yellow axial slice indicates the approximate center of mass in the axial plane to serve as the preliminary gui e for construction of the curved slicing plane, ( b ) A curve with a minimal number of points is drawn in the axial slice, and the sagittal section thickness is changed to about 20 mm. The zone to be reconstructed in the thick - section pseudo- periapical view (top center pane of a ) will then be indicated by the white lines in the axial slice. The yellow axial reconstruction plane indicator is moved in an inferior- superior direction to ensure that the structures of interest are captured within these white lines.

Fig 6-12 (a ) Too many points, even when seemingly well drawn, can lead to “kinks” in the reconstruction and distorted anatomical information. Note the seeming discrepancy in the mesiodistal width of the two mandibular incisors and to a lesser extent the two mandibular premolars. (b ) Correctly drawn arch with only four points showing the matching mesiodistal width of the mandibular incisors and premolars. In a posterior mandibular segment, often only two points are sufficient.

previewed. Study review is a structured, defined process that requires practice, familiarity with the functionality of the software, and a certain degree of confidence that takes some time to develop. The authors have found it useful to describe to the patient the basics of SoS errors, that they are likely to be common in CBCT imaging, and that therefore the area of interest will be looked at last, in the hopes of avoiding such errors. As a preliminary introduction for the patient, the nature of 3 D imaging is explained, and the three-axis planes as well as how they can be independently adjusted and viewed in the different panes are described. The authors have found that creating a pseudo-pan or pseudo-periapical view using curved multiplanar reformatting27 can be very helpful initially in getting one's bearings as well as orienting the patient. The best way to do this is to create a curved reconstruction plane through the axial center of mass and then perform screening of that plane in the sagittal, trans-

sagittal,1 and axial planes. This pseudo-pan or pseudo periapical view with focused-field imagers gives you a single view of the reconstructed volume (Fig 6-11 a) . When the sections are thickened to the width of the al veolar bone (about 20 mm) (Fig 6-11b) and aligned properly (Fig 6-12), the clinician can bring to bear some of the expertise gained from years of periapical radiography to get a gestalt of any areas that might need further exam ination, other than the one for which the examination was prescribed in the first place. The screening process is performed to ensure that clear and compelling find1 When a curved reconstruction plane is used, the plane often curves from one traditional reconstruction plane to another, introducing ambiguity in the description. For instance, in an anterior case, a curved plane from canine to canine will be closest to a coronal plane at the maxillary central incisors, while coming closer to a sagittal plane near the canines. If a larger FOV is reconstructed to include the molars, the reconstructed plane will be sagittal near the molars. The transsagittal plane is a plane that is always perpendicu -

lar to the curved slicing plane.

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Incorporating CBCT Imaging into Endodontics

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f Fig 6- 13 Protocol for screening a CBCT study, (a ) The study is screened first . The transsagittal slice ( lower right ) shows a reconstruction of the max illary second molar. The maxilla is observed as the blue sectioning plane indicator (lower left ) is moved anteriorly, ( b ) The study is screened by moving the blue plane indicator anteriorly. The tooth in Question can be skipped initially and viewed after the screening process is complete, (c) Screening continues anteriorly. The reconstruction plane angle can be adjusted to reflect a reconstruction plane appropriate for the local anatomy, (d ) The study is then screened in the sagittal plane that was previously used as the pseudo- periapical view. The section thickness is reduced to the thinnest section and reviewed in a mediolateral direction with the red plane indicator. Notable findings include evidence of a resorptive area distal to the maxillary sec ond molar visible on the sagittal and axial slices, (e and f ) The study is then screened in the axial plane. The curved reconstruction plane indicator is turned off (e ). Evidence of a distal resorptive defect is confirmed in the axial plane (f ).

ings of significance are not missed due to SoS errors. If there are any non-endodontic findings at this point and the clinician is unsure of their significance, then it is recommended that the study be forwarded to an appropriate radiologist for an additional interpretation. After the global view is studied (Figs 6-13a to 6-13c), it is usually worthwhile to carefully manipulate the study in thin sections in all three planes (Figs 6-13d to 6 13f). With the pseudo-pan or pseudo-periapical view, the transsagittal sections are reviewed. The axial sections are best viewed from coronal to apical, studying each tooth in the FOV. This is best accomplished with the ax -

ial plane positioned perpendicular to the longitudinal axis of the teeth. The remaining coronal or sagittal plane is reviewed in a similar manner. Diagnostic performance is related to the number and types of " schemas" stored in long-term memory. Because endodontists are new to

this technology, we lack the number and quality of engrams necessary for immediate recognition of abnormal ities. Therefore, until such schemas are present, we will have to rely on a scanning strategy to uncover abnormalities or perturbations in the examination . Unfortunately, such a strategy takes much more time and is much more susceptible to error both falsepositive and false —

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Physical Layout have performed an imaging study. Such teeth provide at least some feedback on whether the interpretation was

negative errors. For a better understanding, the reader is encouraged to review the chapters on perception and cognition in A CBCT Primer 1 as well as The Handbook of Medical Image Perception and Techniques.16 After a screening of the study is done and areas of potential interest identified, custom or oblique slicing functions are activated. The authors believe that the best way to avoid error or missing findings is to peruse the axial view first. The axial plane is adjusted and viewed for all teeth in the section from a coronal to apical direction, taking care to visualize all teeth in the FOV. This will usually require four to six complete rotations of the coronal/apical sequence. These views are usually performed using the thinnest slices. When areas of interest are identified, the frontal and sagittal angles are adjusted to give the most efficacious views of said areas. These are typically views that are perpendicular to the longitudinal axis of the tooth. During this viewing process, the clinician should be sensitive to all the artifactual possibilities present, especially those artifacts caused by objects outside the reconstructed FOV. Orthogonal reconstructions will give hint to imaging artifacts occurring in the plane of the contributory materials As a novice, the clinician new to CBCT imaging will not know the expected distribution of findings in either health or disease; therefore, a certain skepticism of any finding that appears abnormal (based on periapical radiography schemas) is prudent. Many clinicians new to CBCT imaging detect all kinds of "pathology," only to find out later that such findings were completely within the normal distribution range. To gain a better appreciation of the importance of this issue, the interested reader should review the chapters on type I and type II errors in A CBCT Primer.1 Using this protocol, clinicians should, with practice, develop skills that enable a relatively rapid method for reviewing a study that minimizes interpretive error and SoS errors. There is no substitute for acquiring all the schemas of normal and abnormal findings in longterm memory. This takes years, so it is better to start at the beginning with a structured process and develop this expertise over time. As endodontists, we are handicapped in that the development of expertise is a function of both the number of reads a clinician has done and the feedback involved, according to medical radiology research.9'23-26 There is also some evidence to indicate that, lacking feedback, the perceptual ma chinery simply might not learn.31 As endodontists, we rarely receive feedback on our reads, except occasionally during surgical procedures. Wood, in her paper on feedback,7 writes that " Feedback is most effective when expected, solicited, and understood. Without a system of constructive feedback, we are in danger of produc ing uncertain and overconfident physicians without adequate self-checks to regulate their activities and decisions." For this reason, endodontists should seek out all opportunities to examine extracted teeth on which they

accurate or not.

Reporting and reports Language of interpretation The language selected to report the interpretation of radiologic findings should be carefully chosen because it can have occult ramifications in the interpretive process and ensuing decision-making. The Radiological Society of North America has published RadLex (www.radlex. org), a lexicon of unified language with 68,000 terms to characterize, organize, and retrieve images and imaging reports, so it should be clear that proper, uniform, and consistent language is important in medical radiology. Because any radiological finding is, in the best case, nothing more than a record of attenuation of photons, one should be careful in describing such findings in the language of health and disease, as has been traditionally and incorrectly done for decades. Therefore, when referring to CBCT imaging, a clinician should not say: " A lesion was found at the apices of the maxillary left first molar " or "The mesiobuccal root of the maxillary left first molar has obvious pathology." A more accurate description of what is observed is to describe the finding using language that reflects an appropriate level of uncertainty and avoids the hidden inferences one makes when using language common to disease states, a practice that is widespread in the endodontic literature, texts, and presentations.2 Such a finding might be better described as: "The maxillary left first molar has a radiolucent finding suggestive of apical pathosis." Using language of appropriate skepticism allows for alternate possibilities and brings to light the hidden inference that is being made with disease-state descriptions. Therefore, it more accurately describes what is actually observed and distinguishes it from inferences that can be made from such observations and the confidence in those inferences. Examples of language used to describe findings and associated confidence related to differentials under consideration include the following:

.

•Inconsistent with •Possible •Not inconsistent with •Consistent with •Suggestive of •Characteristic to •Classic •Pathognomonic 2 Better still is to consider findings in terms of perturbations of the range of normal schema. The reader is referred to The Handbook of Medical Image Perception and Techniques.16

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Incorporating CBCT Imaging into Endodontics

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TDO CBCT Report Patient Katherine Sample Age: 57

Gender: Female

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Ref. Doctor: Dr. Richard Gold Scan Date:6 /12/2014 3:44:42 PM Disc Included: No

Taken By: Dr. Carr Read By: Gary Carr Exposure : 83 KV lOma

Slnos: #14 Sinus secondary to endodontic disease suspected #15 Sinus &&&$& secondary to endodontic disease suspected

Nasal Cavities: Not visualized in this volume Lamina Dura: # 14 Widened apicaQy suggestive ofpathosis # 15 55&Urifid apicaHy suggestive ofpathosis

Osseous Findings: # 14 Suggestive of apical rarefication # 15 Suggestive of apical rarefication

Location of Finding ; # 14 Apical, Impinging Max sinus wall #15 Apical, Impinging Max sinus wall

Finding Size: #14 2mm x 2 mm x 2 mm #15 2mm x 2 mm x 2 mm

Fractures;

None detected Suspected Palpal Anatomy;

#14 Missed MB2, Dilaceration suspected |suspected # 14 Missed DB canal suspected, dilaceration # 14 Heavy calcifications suspected # 14 Fused DB and Palatal root # 15 Dilacerations suspected, heavy calcification suspected

Vital Structures; Floor of the sinus Retrcatment Complexities; #14 Coronal obstructions, suspected aberrant anatomy, There are multiple negatives for treating this tooth # 14 Fused DB and Palatal root #14 Jhc.existing MB instrumentation places the obturation material already dose to the &K suggesting a possible strip perforation #15 Suspected aberrant anatomy, there are multiple negatives for treating this tooth

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14&15 Treatment wiQ compromised existing pericervical dentin

Restorabilitv after Treatment; # 14 55511 require crown # 15 May not require anything except repair of access, should treatment be performed Differential Diagnosis: # 14 CFtfbflfc apical periodontitis # 15 Gjtfpnit; apical periodontitis Recommended Treatment; # 14 Consult and treatment planningbefore proceeding; possible retreatment #15 Recommend no retreatment; observe instead

Prognosis: #14 Good, if no treatment performed; more guarded if retreated # 15 Good, if no treatment performed

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Treatment Plan: #14 Discussion with Q f patient about treatment options before dedding on treatment #15 Recall later for further evaluation

Fig 6-14a Written portion of a TDO CBCT Report.

It is also useful to distinguish between findings and features as we study our imaging. Findings are things that we observe as clinicians as discrete pieces of evidence in support of various hypotheses (differentials) under consideration. In the imaging domain, they are observations one makes on imaging that have a variety of possible explanations. They are used in an inductive direction of logic, from the observations to a possible cause for the observations. Features, on the other hand, are typical manifestations or collections of findings of known processes. They are used in a more inductive direction of logic, from those known processes to likely presentations of those processes. During the interpre-

tive process, one brings to bear the features of known biologic processes, such as the histologic development of a lesion of endodontic origin and likely manifestations at imaging, and correlates those with the radiographic

findings observed at imaging.

The final report and reporting software In the endodontic model described above, the endodontist is generally acting as the ordering clinician, the radiologist, and the surgeon when viewed through the medical model of advanced imaging. However, this

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Preparing the Patient for a CBCT Study

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Other scenarios

The unknown

CBCT imaging may be useful in patients for whom intraoral placement of a film or digital sensor is uncomfortable or difficult because of a strong gag reflex, large tori, large hyperactive tongue, or limited opening. CBCT images are isotropic in nature, meaning that accurate measurements can be made with the imaging software. Measurements can be made to establish a preliminary working length, confirm the final working length, or measure the distance to a patent canal.

The role of CBCT imaging in diagnosing the " unknown" is worth mentioning. What appears to be routine treat -

ment based on a periapical radiograph may have hidden complications like an apical rarefaction, root resorption, perforation, root calcification, anomalous root form, complex canal form, or apical dilaceration, among others. It is very helpful to have this information prior to treatment not only for treatment- planning purposes but also for patient education and consent. While it is difficult to justify screening every patient for " unknown" findings, due to ALARA and other factors, sometimes unexpected findings can completely change the treatment plan (Fig 7 -12).

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CBCT Imaging in Treatment Planning Fig 7-13 (a ) Periapical radiograph of a max illary first molar, ( b) With CBCT imaging, this molar proves to have a complex C - shaped

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Fig 7-14 (a) This maxillary second premolar looked unremarkable on a periapical radiograph. CBCT images revealed a palatal curvature of the root (b) and a deep buccolingual apical split of the canal (c).

it highlights the asymmetry of the canal's location in the root and is suggestive of the presence of a second mesiobuccal canal (see Case 7- 8, page 81, and Case 7-9, page 82). Midroot and apical bi- or trifurcations of canals can make endodontic treatment challenging, and CBCT imaging is sometimes helpful in identifying these features. Success is dependent on the size of the canal (smaller canals are harder to identify), the resolution of the scanner (higher is better), the slice thickness at which the scan can be analyzed (thinner is better), and the ability of the reader to

CBCT Imaging in Treatment

Planning CBCT imaging can be useful in treatment planning for nonsurgical and surgical endodontic treatment and often provides critical information in determining the treatment plan. This is especially true for retreatments (see Case 7 - 6, page 81).

Complex anatomy

manipulate the scan to visualize and interpret the findings (see Case 7-10, page 82). CBCT imaging can also be useful in visualizing root curvatures and the roots' spatial relationships to the buccal and lingual planes (Fig 7-14).

CBCT imaging is useful for distinguishing among root forms, which may influence shaping objectives. Small, delicate root forms, especially if they contain curvatures and/or concavities, may dictate the size and taper of ca nal preparations. Sharp or multiplanar curves may influence the shaping protocol. CBCT images can identify complex root forms such as three-canal premolars, fused roots, C-shaped canal configurations, and dens invaginatus17'18 (see Case 7-7, page 81). For example, prior knowledge of a midroot invagination in a C-shaped molar may influence the clinician to shape the canals to a smaller size or taper (Fig 7-13). Due to the limitations of resolution, CBCT imaging is not always useful in directly identifying untreated canals. However, in many cases the axial view in particular identifies anatomy that is highly suggestive of an untreated canal. A common example is in maxillary first molars. The CBCT image may not identify a discrete canal, but

Calcified canals CBCT imaging can be quite useful in the planning and progression phase of the treatment of teeth with calcified canals. See chapter 11 for a complete discussion of

.

management of calcified canals

Relationship of the tooth to vital structures CBCT imaging helps to determine the relationship of the tooth to structures like the inferior alveolar nerve, mental foramen, greater palatine artery, nasal cavity, and maxillary sinus19 (Fig 7 -15). Some mandibular molar

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7j Clinical Applications of CBCT Imaging in Endodontics

Fig 7- 15 (a ) A large periapical radiolucency was associated with this maxillary lateral incisor that contained a dens invaginatus. (b) CBCT views revealed that the radiolucency extended into the nasal cavity superiorly (red arrow ) , (c) Significant buccal expansion is seen (red arrow ) with minimal remaining bone on the buccal and palatal aspects of the lesion. (Courtesy of Dr Richard Schwartz, San Antonio, Texas.)

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roots are in close proximity to the mandibular canal, and mandibular premolars may be in close proximity to the mental foramen (Fig 7-16). Once this anatomy is identified, extra caution can be exercised during instrumentation and irrigation so as to prevent damage as well as extrusion of intracanal medicaments and obturating

CBCT Imaging During Treatment

materials.

CBCT imaging can be very helpful when a problem is encountered in the middle of treatment. CBCT imaging can be used:

Endodontic retreatment

•To

locate a canal in a tooth with an anomalous root form (see Case 7-13, page 84) •To negotiate calcified canals via assessment of the root form and orientation of the initial preparation to the long axis of the root •To measure the actual depth to where the canal widens and becomes visible (see Case 7-14, page 84) •To visualize the path of a sealer tract in three dimensions (see Case 7-15, page 85) •To assess any occult canal curvatures that may be suggested in traditional images (see Fig 7 -14) •To visualize apical anatomy and assess the main portals of exit, especially if they exit short of the root apex.

Preoperative CBCT imaging helps in the treatment planning for teeth with failing endodontic treatment. Three-dimensional (3D) imaging may shed some light as to the possible cause of failure, such as a missed canal or perforation. This may influence the decision to treat or do surgery, do both, or extract (see Case 7-11, page 82).

Endodontic surgery CBCT imaging can help plan for endodontic surgery. As previously mentioned, it can be used to estimate in three dimensions the actual size, location, and extent of a periapical or periradicular radiolucency. It also allows the surgeon to visualize the thickness of the cortical plates and whether there is through-and-through involvement. The images help to determine the relationship of the roots to vital structures, to the area of bone loss, to each other in a multirooted tooth, and to the roots of adjacent teeth (see Case 7 -12, page 83). They can also show the presence of fused roots. All of this information is critical to know prior to surgical intervention.

Clinical Cases Cases 7-1 to 7 -17, shown in Figs 7-17 to 7 - 31, demonstrate the application of CBCT imaging in endodontic practice.

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Clinical Cases

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Fig 7-17 This patient was referred to the author with pain in the mandibular right quadrant . He pointed to the first molar Periapical (aj and bitewing (b) radiographs revealed no obvious pathology. Clinical tests were within normal limits. CBCT axial (c) and coronal (d) views showed a Tuny impacie third molar with caries ( red arrow ). The patient ’s pain was eliminated after extraction of the third molar.

Fig 7 -18 This patient was referred with pain in the maxillary left quadrant. The maxillary first premolar was hyperresponsive to cold stimulus. No other significant findings were noted. Periapical (a) and bitewing ( b) radiographs revealed no obvious pathology. CBCT serial axial views (c) revealed invasive cervical resorption (ICR) on the distolingual aspect that extended close to the pulp (red arrow ) . Endodontic treatment was performed, followed by surgical repair of the ICR.

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Fig 7 -19 (a ) Periapical radiographs of this previously treated , symptomatic mandibular first molar were unremarkable CBCT imaqinq revealed a midroot furcal radiolucency associated with the mesial root. Red arrows in the axial slice ( b ) and yellow arrows in the sagittal slice (c) point to the radio lucency. The coronal slice (d) hints at the possibility of an unfilled isthmus between the mesiobuccal and the mesiolingual canals le) Retreatment was completed. A CBCT scan taken at the 6-month recall shows osseous repair in the axial (f ) and sagittal (g ) views. The coronal view ( h ) demonstrates the filled isthmus.

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7 Clinical Applications of CBCT Imaging in Endodontics

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preparations Fig 8- 34 An example of a restorative-leveraged access that was modified due to the wide platform. The root canal systems were accessed from two locations, leaving a dentin truss that braces the buccal and lingual walls. (Courtesy of Dr Steve Baerg, Gig Harbor, Washington.)

with a co-observation scope can control the working field with suction and air, and use of rubber dam addresses most of the isolation issues. See chapters 22 and 23 for a more complete discussion of isolation. The primary goal of an orifice-directed access is to preserve structural dentin. As previously mentioned, the pulp horn and a portion of the roof of the chamber may be retained during the access cavity preparation process. The author places files in an EndoHandle (Venta) and customizes the tips to remove tissue remnants from areas that are difficult to access (Fig 8-35). These areas can also be chemically debrided by flooding the chamber with sodium hypochlorite, activated by sonic or ultrasonic devices. There must be a balance between dentin preservation and adequate access to the root canal system. There are valid concerns about increased risk of instrument separa tion with conservative access cavity preparations. In fact, properly designed orifice-directed access cavity preparation eliminates all sharp corners, the areas of highest

sometimes be altered to take advantage of teeth with caries or large restorations (Figs 8-33 and 8 - 34), known 7 as restorative / caries -leveraged access.

Challenges to Conservative Access Cavity Preparations The proposed conservative access cavity preparations discussed in the previous sections come with inherent challenges (Box 8-4). A conservative access cavity must be completely visual. Traditional methods rely primarily on tactile feel, such as dropping into the pulp chamber with a round bur, but many teeth have no chamber. The dental operating microscope addresses the visual challenges and allows the clinician to see every step of the process, identify the restorative-tooth interface, and read the dentin color map. A trained assistant working

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Challenges to Conservative Access Cavity Preparations Fig 8- 35 Modified files in an EndoHandle are useful for removing tissue in pulp horns and under soffits. They can be activated indirectly with ultra-

sonics.

Fig 8 -36 A maxillary molar with paper points projecting from the canals shows how unobstructed access can be obtained to all the canals with a conservative, orifice-directed access cavity preparation.

Fig 8- 37 Endodontic access in a tipped mandibular molar is fraught with danger and requires careful planning. CBCT imaging can be very helpful in planning. (Courtesy of Dr John A. Khademi, Durango, Colorado.)

risk from cyclic fatigue, and allows direct access to every orifice (Figs 8-36 to 8 -38). In addition, most rotary files should not be used for more than a few seconds in each canal. Nickel-titanium (Ni-Ti) files and controlled memory files with smaller tapers and diameters further reduce instrument fatigue.

Overzealous approaches to dentin preservation can lead to procedural accidents and errors. The distalized access shown in Fig 8 - 39 resulted in excessive removal of furcation dentin. Overzealous mesial positioning of the access cavity preparation in Fig 8 - 40 compromised the pericervical dentin. Orifice -directed access does

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Access Cavity Preparations Fig 8- 38 Orifice-directed trajectories of the canals, (d to f ) Red and blue arrows represent canal trajectories, while pink arrows point to pericervical dentin thickness. ( g ) A CBCT axial scan of canals containing calcium hydroxide after initial root canal preparation. Green arrows show that the canals are well centered and that little dentin was sacrificed.

Fig 8- 39 (a and b) Overzealous distalization of the access and aggressive shaping in the mandibular molar led to excessive dentin removal toward the furcation.

Fig 8- 40 (a and b) Overzealous mesialization of the access in the maxillary second molar led to unnecessary dentin removal (red arrows ), (c to f ) The examples shown (blue, green, and pink arrows ) are more ideal.

necessarily mean a tiny access cavity preparation. Working through a tiny access without careful attention to the root divergence can lead to instrument distortion (or separation) and unnecessary dentin removal in the coronal third of the canal. Extending the endodontic acnot

cess or carefully creating a notch on the access outline, usually on the side opposite the canal in question, will

instrument binding and unnecessary dentin removal (Fig 8- 41; see also Fig 8-23).

prevent

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References

Fig 8- 41 Sectioned tooth images show rotary instrume nt restriction. The red arrows indicate the danger zone for binding and file separation. The blue arrows indicate the area where restricted instruments tend to remove excessive dentin. The green arrows indicate the area where the access cavity preparation should be extended to avoid problems in the red and blue areas.

Conclusion The conservative approach to endodontic treatment is gaining wide support among the leaders in the restorative community. While conservative access cavity preparations require more skill and are more difficult and time- consuming than traditional preparations, they maintain more natural tooth structure, most likely extending the functional life of the tooth. Conservative endodontics and considerable remaining tooth structure are common characteristics of endodontically treated teeth that have survived for 20 or more years.

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References .

1 American Association of Endodontists website. Glossary of Endodontic Terms, http://www.nxtbook.com/nxtbooks/ aae/ endodonticglossary/index.php#/2. Accessed 24 July 2014 2 Ferrari M, Cagidiaco MC, Goracci C, et al. Long-term retrospective study of the clinical performance of fiber posts. Am J Dent 2007;20:287-291. 3. Sorensen JA, Engelman MJ. Ferrule design and fracture resistance of endodontically treated teeth. J Prosthet Dent 1990;63:529-536.

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5. Verma P, Love RM. A Micro CT study of the mesiobuccal root canal morphology of the maxillary first molar tooth. Int EndodJ 2011;44:210-217. 6. Rundquist BD, Versluis A. How does canal taper affect root stresses? Int Endod J 2006;39:226-237. 7. Clark D, Khademi J. Modern molar endodontic access and directed dentin conservation. Dent Clin North Am 2010;54: 249-273. 8. Stankiewicz N, Wilson P. The ferrule effect. Dent Update 2008;35:222-224,227-228. 9. LaTurno SA, Zillich RM. Straight-line endodo ntic access to anterior teeth. Oral Surg Oral Med Oral Pathol 1985;59:418419. 10. Zillich RM, Jerome JK. Endodontic access to maxillary lateral incisors. Oral Surg Oral Med Oral Pathol 1981;52:443 45. 11. Ouellet R. Mandibular permanent cuspids with two roots [ in French]. J Can Dent Assoc 1995;61:159 161 - . 12. Wilcox LR, Walton RE, Case WB. Molar access: Shape and outline according to orifice locations. J Endod 1989 15* 315— 318. 13. Krasner P, Rankow HJ. Anatomy of the pulp- chamber floor. J Endod 2004;30:5-16. 14. Trope M, Elfenbein L, Tronstad L. Mandibular premolars with more than one root canal in different race groups. J Endod 1986;12:343-345. 15. Acosta Vigouroux SA, Trugeda Bosaans SA. Anatomy of the pulp chamber floor of the permanen t maxillary first molar J Endod 1978;4:214-219. *

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4. Johnson WT. Endodontic access. In: Color Atlas of Endodontics. St Louis: Saunders, 2002.

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CHAPTER

Mike Gordon, BDS, MDS (Endo), MRACDS (Endo)

The Importance of Working Length Successful endodontic treatment depends on removal of the maximum amount of infected/injured pulp tissue, necrotic material, and microorganisms from the root canal. This can only be achieved if the length of the root canal is determined with accuracy. Working length is the extent to which endodontic instrumentation is taken and subsequent root filling material is placed. On a biologic level, working length is also the level at which a wound is created and will subsequently heal. It is therefore critical for clinicians to distinguish between vital and necrotic/infected tissues. Instrumenting the necrotic/infected tissue to the apical foramen leaves the wound surface in a position that is ideal for healing. In vital cases, the wound surface can be 1 mm short of the apical foramen and still produce optimal healing. In 1930, Grove stated that "the proper point to which root canals should be filled is the junction of the dentin and the cementum" and that "the pulp should be severed at the point of its union with the periodontal membrane."1 The cementodentinal junction (CDJ) is the anatomical and histologic landmark where the periodontal ligament (PDL) begins and the pulp ends. Clinicians therefore employ root canal preparation techniques aimed at making use of this potential natural barrier between the contents of the canal and the apical tissues. However, the difficulty many clinicians face is howto use this landmark to accurately identify and prepare the working length. This difficulty is made all the more challenging by variations in the anatomy of tooth apices due to age and tooth type.

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Armamentaria and Techniques Used to Determine Working Length

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Fig 9- 1 Anatomy of the root apex: 1, the vertex; 2, the major constriction; 3, the minor constriction; a, the

Fig 9- 2 The center of the major foramen (1 ) and the minor foramen (2). The red arrows distance between the major and minor constrictions; represent the MAFD. b, the distance between the major constriction and the vertex. (Adapted from Kuttler2 with permission.)

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Apical Anatomy of the Tooth

Armamentaria and Techniques Used to Determine Working Length

Root To fully appreciate the concept of working length, an understanding of the apical anatomy of the tooth root is required (Fig 9 -1). The apical foramen is the opening at or near the apex of the tooth root. The apical constriction , when present, is the narrowest part of the root canal; it has the smallest diameter of blood supply, so preparation at this point results in a small wound site and optimal healing conditions.3 The location of the apical constriction varies considerably from root to root, and its relationship to the CDJ is also variable. The CDJ is highly irregular and can be up to 3 mm higher on one wall of the root compared with the opposite wall.4 It is for this reason that the apical foramen is a more accurate indicator for determining working length. The minimal apical foramen diameter (MAFD ) is the smallest cross-sectional length of the apical foramen at the apical constriction of the canal that can be determined with gauging files5 (Fig 9-2). In most instances, the MAFD consists of the two closest points on a plane that represent the cavosurface of the canal. An elliptical or irregularly shaped foramen may be wider than this distance. In the rare instance in which the cavosurface of the canal is at the anatomical and radiographic apex of the root and the apical foramen is a perfect circle, the MAFD is the diameter of the apical foramen.

Tactile sense While useful for experienced clinicians and in patent root canals, tactile sense has many limitations. The anatomical variations in size, tooth type, patient age, and apical constriction location make working length assessment with this method unreliable. In some cases, the canal is sclerosed or the constriction has been destroyed by inflammatory resorption. Seidberg et al6 found that, even among the most experienced clinicians, only 60% could locate the apical constriction by using tactile sense.

Radiography The preoperative radiograph has been used for many years to determine the anatomy of the root canal system,

the number and curvature of roots, and the presence or absence of disease as well as to act as an initial guide for working length determination. The radiographic apex is defined as the anatomical end of the root as seen on the radiograph, while the apical foramen is the region where the canal leaves the root surface next to the PDL.7 When the apical foramen exits to the side of the root or in a buccal or lingual direction, it becomes difficult to make out on a radiograph. Olson et al8 found that when files were placed to the foramen in extracted teeth, only 82% appeared to be at the apical foramen on the ra diographs. Dense bone and anatomical structures can make the visualization of root canal files impossible by

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9 Working Length

Fig 9-3 (a and b) Radiographic interpretation alone can be problematic in determining working length and is at best an estimation. Other methods of measurement are required to determine an accurate working length.

Fig 9- 4 A commercially available EAL (Apex ID, SybronEndo).

Limitations of electronic measurement

make the visualization of root canal files impossible by obscuring the apex. The superimposition of the zygomatic arch can also obscure the apices of the maxillary posterior teeth. The deposition of secondary dentin and cementum can move the apical constriction, causing preparation errors.9 Averages used to distinguish the apical constriction from the anatomical or radiographic apex could lead to inaccurate obturation. At best, radiography can give only an estimation of this histologic structure (Fig 9-3).

The majority of current EALs are not affected by irrigants within the root canal, and some are most accurate in the presence of sodium hypochlorite.13,14 Biologic phenomena such as inflammation can also affect the accuracy.15 Intact vital tissue, inflammatory exudate, and blood can conduct electrical currents and cause inaccurate readings, so their presence should be minimized.16 Other conductors that can cause short-circuiting in a second canal are metallic restorations, caries, saliva, and instruments. Care must be taken if any of these variables exist. Similar measurements were obtained using stainless steel and nickeltitanium (Ni-Ti) instruments in the same root canal.17

Cone beam computed tomography Cone beam computed tomography (CBCT) sometimes provides valuable information to clinicians. CBCT images allow accurate measurement of distances in various planes and sections and allow for a more accurate pic ture of canal curvature and general root anatomy.10

The paper point method The paper point method can be very accurate in determining working length and may also give information about the three-dimensional position and slope of the apical foramen.18 This allows for custom cone cutting and placement during obturation. To utilize this method, the canal must be dry and patent and the paper point must pass freely out the apex (Fig 9- 5). If the paper point comes back with the tip buckled, the measurement is not accurate. The extraradicular environment consists of PDL, granulation tissue, pus, blood, bone, or other hydrated tissues. If a paper point is placed into a dried canal and removed short of the apical foramen, it should be retrieved dry (Fig 9-6). If a paper point is placed into a dried canal and taken past the cavosurface of the canal, the portion that extended past the cavosurface will be wet with fluid (ie, blood, pus, serous fluid, or mucus) when retrieved (Fig 9-7). The maximum length a paper point can be placed into the canal and remain dry is recorded as the bleeding point, and this measurement should be the length of the canal used for instrumentation.

Electronic apex locator The electronic apex locator (EAL) is an instrument that, when used with appropriate radiographs, allows for much greater accuracy of working length determination (Fig 9-4). The EAL can accurately reveal where the canal ends and the extraradicular structures (ie, PDL, bone, granulation tissue, cyst) begin.11 Modern EALs are about 90% accurate when determining the apical constriction, but they are reported to be 100% accurate in determining the position of the apical tissues in ideal conditions.12 However, experience is required to determine if the reading is accurate and representative of the apical foramen. When the EAL indicates that the apex has been reached, it means that the very tip of the file is protruding slightly through the foramen.

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Summary

Fig 9- 5 A paper point Passed out the apex of a dry canal will be wet at the tip when retrieved,

—

Box 9-1

Fig 9- 6 Illustration of a paper point extended Fig 9- 7 The maximum length the paper point slightly long. can be extended and remain dry is a very accurate measurement of working length.

Clinical tips for determining working length

•Working length often decreases slightly between the first file to length and final instrumentation, particularly in curved canals. •EAL measurements should be repeatable and consistent. If they are not, do not believe them. •Sometimes, drying the canal and filling it with a nonconducting medium such as ethylenediaminetetraacetic acid (EDTA) paste will produce more consistent readings with

the file •EAL measurements are sometimes more accurateisifrecord is extended past the apex and the measurement ed as you pull it back in.

•Sometimes a larger, tighter-fitting file will produce a more accurate EAL measurement than a small file. •The paper point method works best in canals with small apical diameters.

the EAL.

6. Once an accurate working length is determined, the MAFD can be established. Take Ni-Ti K-files to the paper point length with apical pressure without rotating them; a file of the proper size will bind at, or just short of, the paper point length. This file represents the MAFD. 7. Complete additional instrumentation if necessary. 8. You are now ready to obturate (see chapters 16 and 17).

Determining Working Length Below is a step-by-step guide for determining working length. In addition, clinical tips for working length determination can be found in Box 9-1. 1. Begin with an accurate preoperative radiograph . CBCT scan to estimate canal length and curvature file a , 2. After initial access and coronal preflaring pass with the EAL. to the estimated length as measured initial 3. Establish and maintain patency, complete paper small a place and shaping, dry the canal, by the point 0.5 mm short of the length determined it until it advance , EAL. If the point comes out dry working initial an picks up some fluid. This provides length. of 4. Complete instrumentation to an approximation the final shape and size points. 5. Verify the length a second time with paper This will provide a very accurate final measurement of working length. or

Summary This chapter discussed a method to accurately measure canal length to the cavosurface and determine the MAFD. Once this is accomplished, a suitable preparation and obturation technique can be used for predictable and successful endodontic treatment within the anatomical limits of the tooth.

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Working Length 10. Jeger FB, Janner SF Bornstein MM, Lussi A. Endodontic

References

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working length measurement with preexisting cone-beam computed tomography scanning: A prospective, controlled clinical study. J Endod 2012;38:884-888. 11. Segura - Egea JJ, Jimenez- Pinzon A, Rios- Santos JV. Endodontic therapy in a 3-rooted mandibular first molar: Importance of a thorough radiographic examination. J Can Dent Assoc 2002;68:541-544. 12. Gordon MP, Chandler NP. Electronic apex locators. Int Endod J 2004;37:425-437. 13. Jenkins JA, Walker WA III, Schindler WG, Flores CM. An in vitro evaluation of the accuracy of the root ZX in the presence of various irrigants. J Endod 2001;27:209-211. . 14 Meares WA, Steiman HR. The influence of sodium hypochlorite irrigation on the accuracy of the Root ZX electronic apex locator. J Endod 2002;28:595-598. 15. Kovacevic M, Tamarut T. Influence of the concentration of ions and foramen diameter on the accuracy of electronic root canal length measurement—An experimental study. J Endod 1998;24:346-351. 16. Trope M, Rabie G, Tronstad L. Accuracy of an electronic apex locator under controlled clinical conditions. Endod Dent Traumatol 1985;1:142-145. 17. Thomas AS, Hartwell GR, Moon PC. The accuracy of the Root ZX electronic apex locator using stainless-steel and nickel-titanium files. J Endod 2003;29:662-663. 18. Marcos-Arenal JL, Rivera EM, Caplan DJ, Trope M. Evaluating the paper point technique for locating the apical foramen after canal preparation. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009;108:e101-e105.

1. Grove C. Why canals should be filled to the dentinocemental junction. J Am Dent Assoc 1930;17:293-296. 2. Kuttler Y. Microscopic investigation of root apexes. J Am Dent Assoc 1955;50:544-552. 3. Ricucci D, Langeland K. Apical limit of root canal instrumentation and obturation, part 2. A histological study. Int Endod J 1998;31:394-409. 4. Gutierrez JH, Aguayo P. Apical foraminal openings in human teeth. Number and location. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1995;79:769-777. 5. Rosenberg DB. The paper point technique. Part 1. Dent Today 2003;22:80-86. 6. Seidberg BH, Alibrandi BV, Fine H, Logue B. Clinical investigation of measuring working lengths of root canals with an electronic device and with digital-tactile sense. J Am Dent Assoc 1975;90:379-387. 7. American Association of Endodontists, Subcommittee on Nomenclature. An Annotated Glossary of Terms Used in Endodontics, ed 4. Chicago: American Association of Endodontists, 1984:1-3. 8. Olson AK, Goerig AC, Cavataio RE, Luciano J. The ability of

the radiograph to determine the location of the apical foramen. Int Endod J 1991;24:28-35. 9. Chong BS, Pitt Ford TR. Apex locators in endodontics: Which, when and how? Dent Update 1994;21:328-330.

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CHAPTER

Steven Baerg, DMD Eric Herbranson, DDS, MS

Preparation of the root canal system is the primary focus of nonsurgical endodontic care. Historically, preparation techniques have aimed to fulfill biologic objectives and facilitate obturation requirements. Biologic objectives focus on mechanical and chemical debridement of the root canal system for the prevention and treatment of apical periodontitis, and obturation requirements are based on the primary objectives of filling and sealing the prepared canal space in three dimensions. Both aspects of canal preparation reflect biologic models and available materials and have significant market influences. Practitioners are exposed to a wide variety of technology and techniques for preparation of the root canal system and obturation of the prepared canal space. Over the years, specific mechanical objectives, preparation strategies, and the corresponding treatment endpoints have come to represent the biologic objectives within the context of our current disease model. Within this framework, practitioners focus their attention on the radiographic appearance of process- driven treatment endpoints and substitute a certain radiographic look for actual treatment outcomes. This goal of achieving a specific radiographic appearance and the simplification of our disease model into a binary result have led to overconfidence of anticipated outcomes as well as a tendency for practitioners to overlook other, possibly more important influences on long-term outcomes of treatment and tooth longevity.1'2 Missing from this mindset is an appreciation of the role root canal preparation has on the structural integrity of the tooth. Increased awareness of the need to evaluate and maintain the structural integrity of the tooth, and the important role it plays on the tooth's ultimate longevity, has led to more conservative approaches for the preparation of the root canal system. It is important to understand three essential concepts relating to treatment outcomes when considering potential approaches for care. Patient care will be enhanced if the practitioner understands

and appreciates these distinctions.

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Preparation of the Root Canal System Fig 10-1 The pericervical dentin is an area critical for tooth strength. Conservation of dentin in this area enhances longterm restorative success.

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1 Patient -centered outcomes reflect the outcome measures that matter most to patients, including function, comfort, and longevity. Awareness of the patient's perspective of treatment endpoints and how endodontic intervention may negatively affect tooth longevity is very important to achieving a satisfactory patient-centered outcome. 2. Disease-specific outcomes reflect the affect of treatment on disease. Examples in endodontics include elimination of swelling, a healed sinus tract, or bone regeneration. Disease-specific outcomes tend to be physiologic or biologic in nature and reflective of disease process beliefs that may not be tied to, or even good predictors of, patient -centered outcomes. For example, in endodontics, periapical radiographic findings are generally not reflective of what matters most to the patient. Furthermore, the radiographic presence of an apical radiolucency does not nec-

er those endpoints contribute to a successful diseasespecific or patient-centered outcome. The endodontic literature does not provide an answer to the question of which technique produces the highest success rate relating to endodontic disease; however, we do know that dentin

essarily reflect treatment failure, nor does lack of a radiolucency always reflect success. Radiographic findings are often misinterpreted as or substituted for (and occasionally to the exclusion of) patientcentered outcomes. 3. Process-related outcomes are those in which the endpoint of the intervention itself is used as a proxy for a disease -specific outcome. For example, the radiographic look of root canal treatment is representative of a process-related outcome. If the radiographic look of the treatment is good to the practitioner, it is expected that the treatment will be successful. Successful process-related outcomes often lead to overconfidence that treatment will result in successful disease-specific and patient-centered outcomes.

Treatment protocols that preserve natural tooth structure result in teeth that are stronger, better able to handle functional and parafunctional loads, and more resistant to fracture. In examining endodontically treated teeth, Clark and Khademi3 defined the importance of preserving tooth structure through directed dentin conservation by introducing a hierarchy of tooth needs for optimal strength and fracture resistance. Within this hierarchy, pericervical dentin (dentin roughly 4 mm above and below the crestal bone) is considered a critical area for a tooth to withstand stresses (Fig 10-1). Orifice- directed approaches in access preparations designed to preserve pericervical dentin are described in chapter 8. Extending the concept of directed dentin conservation to canal preparation protects the natural structural integrity of the root by minimizing dentin removal during the preparation process, subsequently increasing the potential for long-term tooth survival. Furthermore, conservative preparation of the canals and the prevention and treatment of apical periodontitis are not

removal weakens the tooth and increases the likelihood of structural failure, irrespective of clinical technique. It is the authors' belief that endodontic procedures should recognize the potential for and minimize the loss of tooth structure, which will in turn maximize the structural integrity of the tooth, and that maintaining the structural integrity of a tooth is at least as important as achieving the biologic objectives of endodontic treatment.

Model for Longevity

The nature of the endodontic literature is such that we often seek to achieve process-related endodontic endpoints (eg, a negative culture from a canal or a large apical preparation size) with no real knowledge of wheth-

mutually exclusive objectives. 110

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Principles of Radicular Dentin Management

Fig 10- 2 A conservative approach respects root morphology and mimics the natural canal anatomy.

Fig 10- 3 Traditional access and canal preparation includes removal of radicular dentin triangles.

Fig 10- 4 Orifice-directed access preparations preserve the pericervical dentin triangles and help maintain the structural integrity of the tooth.

Preservation of radicular dentin in the pericervical area

Principles of Radicular Dentin Management

Traditionally, the structural importance of coronal radicular dentin has been superseded by the technical requirements for endodontic treatment. Many traditional techniques consider coronal flaring desirable and accomplish this with medium to large Gates Glidden drills. "Triangles " of radicular dentin found proximal to the canal orifice in posterior teeth and sometimes referred to as lingual shelves in anterior teeth have been designated as treatment liabilities requiring removal (Fig 10- 3). This sacrifice of dentin is in response to the perceived need for straight- line access to facilitate the preparation process. Removal of radicular triangles of dentin facilitates more direct vertical approaches, but because this dentin is located in the pericervical area, the root - form alterations unnecessarily weaken the tooth. Straight -line access is not a prerequisite for treatment with current technology and has never been associated with enhanced treatment outcomes related to apical periodontitis. Orificedirected access approaches in posterior teeth and incisal access approaches in anterior teeth mitigate the loss of pericervical dentin and do not require the removal of radicular dentin triangles (Fig 10- 4).

Strategies for radicular dentin management require case-specific approaches. The universal application of standardized treatment approaches to achieve a particular radiographic look has the potential to miss opportunities to conserve dentin and ultimately enhance longevity. Any approach to canal preparation should respect the natural canal anatomy and root morphology of the tooth, and the ideal radiographic appearance should be one in which the natural pretreatment canal anatomy is preserved as closely as possible in regard to taper, curvature, and apical foramen size and location (Fig 10-2). To achieve this objective, the practitioner must follow specific core principles, including the following: ( 1 ) minimize coronal flaring to preserve radicular pericervical dentin; (2) carefully evaluate and respect root morphology; and (3 ) maintain the anatomy of the canal system. The practitioner must consider biologic objectives and technical capabilities as well when designing treatment strategies.

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03 Preparation of the Root Canal System Fig 10- 5 Initial scouting files help determine the degree of coronal curvatures and canal convergence profiles.

Fig 10- 6 Canal convergence profiles determine the amount of tooth structure that needs to be removed coronal to the pericervical dentin area for the orificedirected approach.

Initial scouting of the coronal canal system with hand files provides valuable feedback regarding the orientation of the orifices and convergence profiles (Fig 10- 5). Armed with this information, the clinician can preserve coronal root dentin at the expense of the less important dentin and restorative materials coronal to the pericervical area. The canals generally project toward the middle of the occlusal surface, and access should always be ap proached in such a way that it follows the natural canal projections and minimizes the loss of dentin in the area around the orifices (Fig 10- 6). While pre-enlargement is an acceptable aid in certain case types, the expenditure of dentin should be judicious, and decisions should be made based on orifice-directed canal projections and root morphology, not a standard generalized protocol.

advent of in-office focused-field cone beam CT (CBCT) technology allows practitioners to obtain detailed, casespecific insight regarding canal anatomy and root outline form (Fig 10-8). Combining the knowledge of general tooth anatomy and its variations gained through the study of the tooth atlas with the case-specific insights offered by in-office CBCT scans makes it possible for clinicians to develop highly accurate mental models of canal anatomy and root morphology. These models reflect general anatomical realities, including the following: ( 1 ) root dentin is generally thin; (2) root concavities are common, and this significantly reduces dentin thickness; (3 ) molar roots frequently have curves in the coronal third; and (4 ) a minimal root-form taper exists in the middle and coronal thirds, and this is mirrored by the taper of the canal (Fig 10-9). Armed with this knowledge, clinicians can develop case-specific strategies for practical applications (see section later in this chapter).

Approaches that respect root morphology Decisions involving alterations to radicular dentin must also be respectful of the presenting root-form morphology. This requires a thorough appreciation and awareness of the many potential presenting variations in root morphology and canal anatomy. The practitioner must be knowledgeable about tooth anatomy and acutely aware of the role it may play in canal preparation, procedural accidents, and the structural demands for longevity. The Tooth Atlas (Tooth Atlas v7.0, eHuman.com) is a valuable resource that uses high-resolution computed tomography (CT) scans of human teeth to illuminate the great diversity of root morphology and fine root canal anatomy within teeth (Fig 10-7). Study of these reconstructions aids the practitioner in developing accurate mental models. Additionally, the

Maintaining canal anatomy Traditional canal preparation strategies generally fall into two groups: one advocating aggressive, continuous funnel-tapered canal preparations in combination with minimal alteration to the apical foramen size, and the other advocating less-tapered preparations with active preparation of the apical extent of the canal to larger sizes.4,5 These strategies have rationales based on perceived disinfection requirements and/or obturation requirements, and both impart significant negative alterations to canal anatomy in achieving these requirements. The authors advocate an alternative strategy based on the desire to maintain the tooth's structural integrity fol112

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Principles of Radicular Dentin Management

Fig 10-7 High-resolution CT scans offer valuable insight into root morphology and canal anatomy.

Fig 10- 8 Focused-field CBCT image of a maxillary molar taken after an endodontic

pro-

cedure.

Fig 10- 9 This mandibular molar is somewhat typical in that it has fairly minimal taper in the coronal and middle thirds of the root and canal

.

titis.1 Dentin preservation should be one of the primary considerations when altering the natural canal taper for any technique, and careful pretreatment assessment will offer the practitioner important insights into potential approaches for managing the preparation taper. In addition, management of preparation taper is significantly influenced by root-form morphology and presenting ca nal curvature. The natural taper of the canal system and root form often mirror one another with minimal taper, and root canal width is typically inversely related to root dentin thickness. Large tapers are particularly undesirable in roots with wider canals, both from a structural standpoint and because of the potential for midroot concavities that are susceptible to strip perforations due to limited dentin thickness. Although narrower canals have the potential to afford more latitude with preparation taper

lowing canal preparation. The aims are to (1 ) minimize alterations to the root structure through less-tapered canal preparations; (2) maintain the natural flow of the canals by respecting canal curvatures with generally smaller shapes; and (3 ) maintain the apical foramen size and location via limited modification of the apical canal anatomy. This strategy represents an appropriate balance between the perceived biologic requirements for successful treatment and the structural requirements of the tooth for longevity.

Taper Canal taper is determined by the relationship between the apical foramen size, canal orifice size, and canal length. Naturally occurring canal taper tends to be relatively parallel and nonstandardized. Historically, the rationale for degree of taper during canal preparation has been largely empirical.6 The introduction of nickeltitanium rotary instrumentation has facilitated canal preparations with a variety of predefined tapers, yet specific degrees of taper have not been associated with improved outcomes in the resolution of apical periodon-

due to increased thickness in dentin walls, indiscriminate and excessive taper preparation negatively impacts root strength; therefore, minimizing the arbitrary expenditure of root dentin with conservative preparation taper profiles offers the more prudent approach for care.

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03

Preparation of the Root Canal System Fig 10-10 Instrument modification can vary in type and degree. Modifications should be directed, purposeful, and reflective of the intended use.

Fig 10-11 Apical canal profile and taper as seen through a passive "step back” of 0.02 taper hand files.

on curvatures can lead to unnecessary canal alterations in dentin-sensitive locations.

Curvature The degree of canal curvature is a variable with the potential to significantly influence the technical approach of the preparation process (see chapter 12). Schilder described preparation processes that mirror natural cur7 vature as achieving a sense of flow. He emphasized the importance of recognizing and respecting multiplane curvatures throughout the preparation process and cautioned against straightening the curvatures with aggressive preparation and deviations from the natural canal path. Negotiation of both coronal and apical canal curvatures is achieved through selective modification of instruments in discovering the natural canal anatomy and determining the degree and orientation of curvatures. Instrument selection and modification should vary based on pretreatment assessment and intratreatment feedback. Any instrument modification should be purposeful and representative of its intended purpose. The type of instrument modification (bend or curvature) and degree of modification (sharp or gentle) should be reflective of the emergence profile and natural obstructions coronally and presenting canal anatomy apically (Fig 10-10). Once the curvatures are established, initial coronal scouting files require frequent reproducible negotiations to minimize unintentional anatomical deviations and iatrogenic mishaps in this region Only after this initial path is discovered and established should instruments be advanced further apically. More gentle curvatures encountered in the midroot region require flexible instruments that remain centered in the canal. Failure to recognize the significance that specific instrument designs impart

Apical anatomy Historically, variations in apical preparation designs have reflected alterations to accommodate desired treatment endpoints for disinfection and/or obturation. However, strategies that increase the size of the apical preparation have not been associated with improved outcomes and actually increase the potential for technical error.8 Common errors encountered include transporting the location of the natural foramen (perforation), changing the shape of the foramen through repositioning (" zipping"), and transporting the canal short of the foramen (ledging/apical stop). To avoid these errors, practitioners should not be encouraged to actively enlarge the apical preparation to predetermined sizes but should instead utilize approaches to maintain the natural anatomy and minimize apical alterations. The instrumentation of apical canal anatomy is most predictably achieved following the discovery and established negotiation of coronal canal anatomy, which addresses impediments influenc ing tactile feedback and apical advancement. As with initial coronal scouting, purposeful and directed instrument modification is necessary to minimize unintentional alterations to the apical anatomy. Instrument modification for apical preparation is typically limited to case-specific custom curving of the terminal 3 mm of files. Initially, the degree of curvature is determined by mental modeling, imaging, and tactile feedback from use of small-diameter instruments. Following confirmation of the

.

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Practical Applications Fig 10-12 Root form-appropriate canal preparation is attainable with a 11

multitapered file with appropriate flute diameters reflective of the natural canal system profile. The increased apical taper of this file blends into the minimal coronal taper, offering conservative dentin removal and increased coronal flexibility of the file to reduce canal transportation during shaping.

•

Recommended maximum flute diameters (MFD)

MFD (mm)

Tooth Most teeth

0.9

Maxillary central incisors

1.1

Mandibular anterior teeth

0.6

Maxillary molars

0.8 (MB1, DB, P); 0.6 (MB2)

Mandibular molars

0.8 (M, D); 0.6 (MM)

MB1, first mesiobuccal; DB, distobuccal; P, palatal; MB2, second mesiobuccal; M, mesial; D, distal; MM, middle mesial.

natural apical anatomy, instrument modification should mirror this anatomy through the serial precurving of instruments to be used. The periodic and purposeful movement of select small-diameter files beyond the apical foramen, ensuring canal patency throughout the preparation process, helps minimize the aforementioned errors. Also, frequent gauging of the foramen size throughout the preparation process enables the practitioner to most effectively ensure adequate apical debridement and provides valuable feedback regarding apical taper and obturation considerations. Gauging the foramen is achieved through the relatively passive use of hand files with limited taper (0.02). Realized increases in apical foramen size during the preparation process should be attributed to the practitioner's ability to more accurately gauge the apical foramen throughout the process and should not be the result of purposeful active enlargement of the foramen. The apical canal profile and final taper is determined through the passive placement of hand files (0.02 taper) increasing in size to the point of binding. The apical taper profile will mirror the "step back" of the files out of the canal (Fig 10-11).

vative maximum flute diameter (MFD) that is respectful of the dentin width in the coronal third of the canal. Files with small tip diameters and correspondingly small MFDs are beneficial in treating small-diameter roots. They also have the advantage of greater flexibility, which, combined with new metallurgy, lessens the potential straightening of the coronal part of the canal as well as reduces the potential for canal transportation and strip perforation. Most importantly, by maintaining more pericervical dentin, this design minimizes the negative influence preparation procedures impart on root strength (Fig 10-12). While the authors believe that preparation decisions should be based on a thorough understanding of principles and not generalized cookbook approaches, a list of recommendations of MFDs for various roots is presented in Table 10-1. These recommendations are based on the average dimensions of teeth, the appreciation for concavities, and the arbitrary rule that no more than Vz of the root dentin should be removed from any given root. These recommendations should be considered as the maximum limit and used as general guidelines easily adapted to and adjusted for case-specific

presentations.

Practical Applications

Anatomical areas of concern The following is not intended to be an in-depth review of tooth anatomy but rather a supplement to point out the unique areas of concern when engineering dentinconserving access and canal preparations. Practitioners should be mindful of the correlation between the external anatomy of a tooth and the internal pulp anatomy. The internal canal anatomy mimics the external canal anatomy due to the constant rate of dentin deposition around the root form during tooth formation (Fig IQ13). This understanding enables the development of a mental model of canal anatomy for specific case presentations. For example, a root with two canals will always have a concavity in the external surface, with the predictable minimal dentin volume found in such a configuration, while roots with single ovoid canals most proba bly have ovoid root forms and lack a concavity.

Instrument selection in a directed approach requires the practitioner to have a thorough understanding of file profile, flute diameter, and structural changes the instrument imparts on the root itself. In addition, an appreciation and respect for general anatomical nuances and specific areas of concern is necessary to direct predictable case -specific approaches to care.

File profile and flute diameter The

most

effective rotary instrument profiles are multita-

pered, with adequate apical taper and minimal coronal taper. Ideally, apical file taper approximates 0.06 for 3 to 4 mm, and the coronal taper approximates 0.02 to 0.00 for V2 to Vz of the file. This design exhibits a more conser-

115

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EH

Preparation of the Root Canal System

Fig 10-13 The cross- sectional outline form of Fig 10-14 The incisal- guided palatal access of this the root mirrors the canal outline form. (Cour- maxillary central incisor utilized a small notch on the tesy of Dr David Clark, Tacoma, Washington.) palatal side of the incisal edge as a guide. Maximum pericervical dentin is preserved with this approach.

Fig 10-16 Cross sections of mesiobuccal roots of the maxillary first molar show a variety of root outline forms, Mesial concavities are common and produce a root with two canals. The dentin width at the second mesiobuccal canal is thin, and this characteristic must be considered in the preparation protocol to prevent strip perforation and structural weakening.

Fig 10-17 A computer model of a real maxillary molar in cross section displays an extreme curve in the cervical third of the MB2 canal. Direct projection of this canal is not possible, and modification of the coronal part of the canal profile is necessary for reasonable access to the canal system,

Fig 10-15 A cross section of a maxillary molar is shown exhibiting a palatal root with two canals and an associated concavity. (Courtesy of Dr David Clark, Tacoma, Washington.)

Fig 10-18 A significant difference exists between the mesiodistal and buccolingual width of mandibular incisors. The central axis exits to the facial of the incisal edges, offering an ideal access location. An access through the incisal edge is recommended in a tooth with a worn incisal edge,

form. The first premolar typically has two roots with a deep concavity on the mesial side of the root, increasing susceptibility to strip perforations. The second premolar has one or two roots with a lesser concavity. They both tend to have a narrow, ribbon-shaped pulp chamber that requires care in the access procedure and the use of small-diameter burs. When presenting with single roots, they are often very thin and "spindly" and should only be prepared with small instruments and minimal coronal flaring.

Maxillary anterior teeth

root

Maxillary anterior teeth are the least problematic teeth anatomically. They generally have a rounded cross section with no root concavity. An exception is the canine, which can have a slight concavity in the mesiodistal (MD) dimension. Clinical significance lies in the reality of potentially less dentin than may appear on a conventional radiograph. Ideal straight-line access to the canal can usually be obtained in anterior teeth through the lingual aspect of the incisal edge. This approach leaves the pericervical dentin with minimal alteration, and a conservative access results in minimal loss of tooth structure and strength (Fig 10-14).

Maxillary molars Maxillary molars are arguably the most complex tooth type in regard to root morphology and canal anatomy, typically exhibiting three roots and four canals. The palatal root is the largest root and usually fairly straight, although a sharp apical curve toward the buccal may be present and unidentifiable on conventional periapical radiographs. This root occasionally has two canals with a palatal concavity

Maxillary premolars Maxillary premolars are characterized by root forms exhibiting a narrow MD dimension and a wide buccopalatal dimension. The size of the clinical crown form hides a much smaller

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Practical Applications

Fig 10-20 A mandibular premolar was accessed through a buccal approach made possible because the central axis of the tooth actually ran through the cusp tip. This approach, respectful of root morphology and utilizing root form-appropriate preparation, facilitated the patient 's desire to retain his 50-year-old gold crown.

Fig 10-19 A mandibular anterior tooth was accessed through an incisal approach

.

facilitated by the significant wear present Two canals were accessed despite the conservative preparation protocol.

on the palatal side of the root (Fig 10-15). This concavity minimizes the amount of available dentin, and this configuration should preclude the use of a restorative post. The distobuccal (DB) root is often fairly straight but varies. A sharp distal curve at the apex of the DB root is fairly common. The mesiobuccal (MB) root tends to be the most problematic root of the maxillary molar. It is typically kidney bean shaped in cross section and usually has a concavity on the furcation side of the root (Fig 10-16), reflective of a second canal rate reported as high as 90%. Therefore, the practitioner must assume the presence of a mesiopalatal canal (or second mesiobuccal canal, MB2) until proven otherwise. The MB2 canal is most commonly mesial to a line between the MB canal and the palatal canal. It usually has some degree of curvature, which may present an emergence profile requiring selective coronal restorative or dentin sacrifice (stepped access) for improved access (Fig 10-17). The dentin tends to be thin in the area of the MB2 canal and may be less than 2 mm in width, even in the coronal portion of the root. The small size and curves require a delicate approach and the use of files with small

Mandibular premolars The mandibular premolar is typically considered a simple tooth, but a small percentage of them can be quite complex and exhibit multiple canals. If multiple canals are present, concavities and/or grooves will also be present, considerably reducing the amount of available dentin. Only small instruments should be used in multicanal teeth, and restorative posts are prohibited. The centerline of mandibular premolars extends through the buccal cusp tip. Ideal access is obtained just lingual to this and involves the buccal triangular ridge, not the central groove (Fig 10-20).

Mandibular molars Mandibular molars have more complexity in canal anatomy than a cursory examination would indicate. There tends to be significant concavities on the furcation side of the mesial root and, to a lesser degree, on the distal root as well (Fig 10-21). These concavities require care because they limit the amount of dentin the practitioner has to work with and require small flexible files to avoid overwidening the canal and transporting it to the furcation side. Overzealous use of instruments with larger MFDs can result in strip perforations into the furcation

MFDs.

Mandibular anterior teeth

and weakening of the root. When a middle mesial ca nal is located, the dentin is considerably thinner and requires the use of the smallest instruments. The presence of two distal canals indicates a furcation-side concavity on the distal root, and care should be taken with conservative preparation. If a post is indicated with this configuration, either two very small posts or a cast post should be used. Three-rooted mandibular molars have a typical mesial root configuration and two distal roots: one main root slightly displaced to the buccal and a difficult-toaccess distolingual root. Much of the time the third root has a sharp apical curve toward the buccal that is not evident on conventional radiographs. These require awareness and careful approaches to treat effectively (Fig 10-22). Mandibular molars with C -shaped canal sys-

Mandibular anterior teeth have a narrow MD root width that, similar to the maxillary premolar, requires small burs and instruments with a careful approach. There is minimal room for error in the access procedure. Anatomically, two canals are exhibited 50% of the time. Typically, the centerline of this tooth is facial to the incisal edge; because of this, ideal access approaches are through the facial surface (Fig 10-18). This approach preserves critical lingual dentin and offers improved predictability through improved visibility. Modern composite restorative materials allow for the esthetic repair of this access approach. If there is significant incisal wear, the access should be directed toward the middle of the worn incisal surface (Fig 10-19).

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Preparation of the Root Canal System

Fig 10- 22 The distolingual root in this three-rooted mandibular molar curves sharply toward the buccal (a configuration referred to as radix entomolaris) . This is not obvious on the typical periapical radiographic representation. The presence of a third root also changes the expected location of the distal canal(s) and requires modification of the access approach to accommodate this as well as the buccal-oriented canal projection of the distolingual canal.

Fig 10- 21 A computer model of a mandibular first molar in cross sec tion displays the very common mesial concavity and distal concavity on the furcation side of the roots. The root is very thin in this area, and if a middle mesial canal is present, only small instruments should be used to prevent strip perforations and excessive weakening of the tooth.

t Fig 10- 23 Treatment sequence: ( 1 ) Incisal access approach. (2) Initial scout ing with 0.08 and 0.10 precurved hand files. (3) Canal negotiated with nos. 10, 15, and 20 hand files to binding and length determination. (4 ) 20/06 rotary file to binding (short of length). (5) Hand files are sequentially passively introduced until resistance is met. The apical profile is discovered and the taper profile determined.

standard of care in endodontics. Although case - specific approaches vary based on presenting variables, sequence patterns in treatment protocols can be observed (Fig 10- 23 to 10-25). Generally speaking, these directed approaches followed similar basic protocols:

complicated and should be referred to specialist, if possible. See chapter 15 for a discussion of treatment of teeth with C-shaped configurations.

terns can be very

a

Representative cases

.

1 Scouting, discovery, and analysis of coronal canal

Preparation strategies that respect the aforementioned principles and appreciate morphologic and anatomical nuances have the potential to culminate in endodontic care representative of a patient-centered outcome. In addition to a thorough understanding and appreciation of instrumentation, utilization of available technology further enhances the level of care provided. For example, the proficient use of a surgical operating microscope is critical in providing predictable care with routine endodontic procedures and has long been recognized as a

anatomy with hand files 2. Light coronal preparation with tapered rotary files, if indicated based on scouting feedback, to facilitate the canal emergence profile 3. Canal length and curvature determination 4. Passive canal body preparation utilizing hand instrumentation and rotary instruments alone or in combination 5. Apical gauging and apical canal profile discovery

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Fig 10-24 Treatment sequence: (1 ) Restoratively lever- n. aged, orifice-directed, stepped access is performed. (2) Mr Initial scouting with 0.08 and 0.10 precurved hand files m of and determination canal emergence profiles. (3) Profiledirected light orifice preparation with variable-taper rotary files. (4 ) Canals negotiated with nos. 8, 10, and 15 hand files to binding and length determination . (5) 20/06 rotary file to binding (short of length) in buccal canals and closer i to length in the palatal canal. (6) Hand files are sequential- 1;:k ly passively introduced until resistance is met. The apical profiles are discovered and the taper profile determined.

H

Fig 10- 25 Treatment sequence: ( 1 ) Restoratively leveraged, orifice-directed, stepped access is performed. (2) Initial scouting with 0.08 and 0.10 precurved hand files and determination of canal emergence profiles. (3) Profile-directed light orifice preparation with variable-taper rotary files. (4) Canals negotiated with nos. 8, 10, and 15 hand files to binding and length determination. (5) 20/06 rotary file to binding (short of length) in mesial canals and closer to length in the distal canal. (6) Hand files are sequentially passively introduced until resistance is met . The apical profile is discovered and the taper profile determined.

3. Clark D, Khademi J. Modern molar endodontic access and directed dentin conservation. Dent Clin North Am 2010;54: 249-273. 4. West JD, Roane JB, Goerig AC. Cleaning and shaping the root canal system. In: Cohen S Burns RC (eds). Pathways of the Pulp, ed 6. Philadelphia: Mosby, 1994:179-218. 5. Trope M, Debelian G . Endodontic Treatment of Apical Periodontitis. In: 0rstavik D, Pitt Ford T (eds). Essential Endodontology, ed 2. Oxford: Blackwell Munsksgaard, 2008:347-380. 6. Peters O, Peters C. Cleaning and shaping the root canal system. In: Hargreaves KM, Cohen S, Berman LH (eds). Pathways of the Pulp, ed 10. Philadelphia: Mosby, 2011:283-348. 7. Schilder H. Cleaning and shaping the root canal. Dent Clin North Am 1974;18: 269-296. 8. Friedman S. Expected outcomes in the prevention and treatment of apical periodontitis. In: Orstavik D, Pitt Ford T (eds). Essential Endodontology, ed 2. Oxford: Blackwell Munksgaard, 2008:408-469.

These routine cases (see Figs 10- 23 to 10- 25) repreapproaches that adhere to the principles of radicular dentin management in concert with anatomical knowledge and technical proficiency. The patient is the ultimate benefactor of an approach that focuses on tooth longevity. sent preparation

;

References 1. Ng YL, Mann V, Rahbaran S, Lewsey J, Gulabivala K. Outcome of primary root canal treatment: Systematic review of the literature—Part 2. Influence of clinical factors. Int Endod J 2008;41:6-31. 2. Ng YL, Mann V, Gulabivala K. Tooth survival following non-surgical root canal treatment: A systematic review of the literature. Int Endod J 2010;43:171-189.

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CHAPTER

Sashi Nallapati, BDS

Clinical

Management of

Clinical management of calcified teeth makes up a significant portion of current endodontic practice. People are living longer than they used to, and many wish to retain their natural dentition. A history of multiple restorations, chronic irritation from deep restorations or cracks, trauma, and vital pulp therapy can result in moderate to severe calcification of the pulp chamber as well as the root canal system.1 Pulp stones (in the pulp chamber), sclerotic dentin (usually in the pulp chamber), dystrophic calcification (in the root canals), and pulp canal obliteration (both in the pulp chamber and the root canal) are some of the clinical situations commonly encountered by endodontists (Fig 11 1). -

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Armamentaria and Techniques for Locating Calcified Canals

Box 11-1

Essential armamentaria for locating calcified canals

•Cone beam computed tomography imaging (Kodak 9000 3D, Carestream Dental)

•Surgical operating microscope for magnification and illumination (Global Surgical)

•External light source for transillumination (Endure Medical)

visualiza •Small-size mirrors (size no. 1, 2, or 3) for better vision in

tion of the pulp chamber space under indirect tight areas (Excellence in Endodontics 2 [EIE2]) •High- and low-speed long, tapered fissure burs (EndoGuide, SS White Dental) •Munce Discovery Burs (CJM Engineering) •Round-ended ultrasonic tips (EIE2) •Microdebriders (Holt Dental Supply) •Endodontic explorers (DG16, JW17, C K Dental Specialties) •File holders (Logan handles, Pearson Dental) •Stiff files (Path files, C and C+ files, Dentsply) •Ethylenediaminetetraacetic acid (EDTA) •Dyes (methylene blue, fluorescein sodium, Sable Seek [Ultradent]) •Radiopaque irrigants (hypaque)

Fig 11-1 An assortment of pulpal floor calcifications.

Armamentaria and Techniques for Locating Calcified Canals

Cone beam computed tomography The Shannon-Nyquist theorem states that, in order to visualize an object predictably on a cone beam computed tomography (CBCT) scan, the resolution of the CBCT must be no greater than one half the size of that object.2 For example, visualization of a calcified canal that can only accommodate a no. 10 hand file (0.10 mm at the tip) requires a scanner with a voxel size of 0.050 mm or less. Presently there are no CBCT scanners on the market with a voxel size less than 0.076 mm. The limitations in resolution as well as the "noise" in three-dimensional (3D) imaging due to scatter, streaking, and reconstruc tion artifacts limit the application of CBCT technology in locating calcified canals. However, CBCT is quite useful in the planning and progression of treatment. CBCT imaging helps to assess the root form and the orientation of the prepara tion in relation to the long axis of the root, especially in the buccolingual dimension (see Case 11- 2, page 125). Because CBCT images are isotropic in nature, they can be used to measure the actual depth of the canal entry point (see Case 11-3, page 126).

The dental armamentaria essential for successful identification of calcified canals are presented in Box 11-1. Below are brief descriptions of selected armamentaria and techniques to locate and treat teeth with calcified canals.

Radiography Angled radiographs Angled radiographs in combination with object localization, like the SLOB (same lingual, opposite buccal) rule, can be used to locate calcified canals (see Case 11-1, page 124). Bitewing radiographs in posterior teeth provide a distortion-free assessment of the true depth of the pulp chamber. They allow the operator to assess the depth and orientation of initial preparation into a calcified pulp chamber as well as the risk of perforation (Fig 11-2).

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Clinical Management of Calcified Teeth Fig 11-2 Bitewing radiographs used to assess the direction and depth of the troughing. The endodontic access was directed toward the furcation (yellow arrow ). An adjustment was necessary to stay aligned with the long axis of the root (red arrow ).

shows the color Fiq 11- 3 The pulpal floor viewed under high magnification

dark-colored pulpal floor differences between the light -colored axial dentin and primary and reparabetween differentiate to critical is information This dentin different when it is looks dentin the how Note . canals tive dentin when locating ways. dry (a ) versus wet (b). It is often helpful to view the chamber both

.

Fig 11-4 Small intraoral mirrors (a )\ tapered, diamond-coated, round ultrasonic tips (Excellence in Endodontics 2) (by, and Munce Discovery Burs (c) are helpful aids when treating teeth with calcified canals, (d) Transillumination with the help of an extraoral light source highlights the calcified dentin (red arrows ).

Dental operating microscope The dental operating microscope provides a clear view of the pulpal floor, exposing subtle color distinctions between primary and reparative dentin (Fig 11-3) in the axial and pulpal floor (see Case 11-4, page 126). This information can be used to differentiate between the dentin and canals that require removal and those that can be preserved to retain the structural integrity of the tooth. Ultimately, this helps the clinician to be as minimally destructive as possible when it comes to endodontic treatment (see Case 11- 5, page 127).

Locating ring calcifications with the dental operating microscope Dentinal tubules are oriented in a radial pattern around the root canal space. In single-canal teeth, there is a round area of darker, calcified dentin surrounded by lighter primary dentin. Sometimes there is a dark dot in the middle of the circle, which represents the patent or calcified canal.3 This pattern is sometimes referred to as ring calcification or a target pattern, and it can be viewed through the dental operating microscope. Sometimes transillumination through the tooth from an external light source can also aid in visualization (see Fig 11- 4d). The " bullseye" can be followed apically within the dark dentin to locate the patent canal (see Case 11-6, page 127).

This same phenomenon helps in locating calcified canals in highly calcified pulp chambers in posterior teeth (see Case 11-7, page 128). Generally, canals are connected by fissures or grooves. If these grooves are traced apically, sometimes they lead to canals at the ends or in the corners of the dark dentin if there are more than two canals. Sometimes troughing the grooves will also uncover small canals in the middle

.

Troughing techniques Troughing that balances careful carving of calcified dentin while preserving the healthy dentin is the hallmark of good endodontic practice. Troughing refers to the careful removal of dentin in the calcified pulp chamber under high magnification and illumination. This can be accomplished with low -speed stain less steel burs or round-ended ultrasonic tips (Fig 11- 4). These instruments are used in a carefully crafted brushing motion, usually under dry conditions for better visualization. Intermittent wetting of the operating field will cool the dentin surface and provide a different look to the " dentinal map / This alternate pattern of dry and wet troughing provides the contrast necessary to view the subtle color changes between primary and reparative dentin. Patience is an important clinical virtue when attempting to trough calcified teeth (see Case 11-8, page 128).

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Clinical Management

HAAG-STREIT INTERNATIONAL

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Fig 15-2 (a and b) Teeth with the C- shaped canal configuration are typically mandibular second molars with a fused, conical root form.

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15-3 An endodontically treated mandibular second molar with a broad foramen exiting short of the radiographic terminus.

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apical direction (Fig 15- 6). The axial view also allows the clinician to visualize external developmental grooves that may affect the periodontal prognosis. Teeth with a C-shaped configuration are subject to many possible morphologic variations. A " classic " C-shaped canal configuration has a continuous isthmus of tissue connecting all the points of negotiation (Fig 15 -7 ), forming a shape similar to the letter C oriented toward the buccal aspect of the tooth. This pattern may be either partially or fully continuous to the apex. Another common configuration has a band of dentin that sepa rates the mesial and distal points of negotiation, often in a semicolon shape (Fig 15 -8). Another configuration may have prominent mesial and/or distal orifices like a typical mandibular molar with small lateral isthmus extensions to

Diagnosis Most teeth with a C-shaped configuration are readily identifiable with periapical radiographs. Their roots tend to have a fused and conical appearance (Fig 15-2). Some or all of the canals usually merge short of the apex (Fig 15 -3). Most of the time the contralateral tooth is also C-shaped (Fig 15- 4). Inside the chamber, the canals line up along an isthmus in the shape of a C pointed toward the buccal aspect (Fig 15-5). In cases where the diagnosis is unclear, cone beam computed tomography (CBCT) can be very useful. The axial view provides a special appreciation of the canal configuration as it dynamically changes from the coronal

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IS

Clinical Management of C-Shaped Canal Configurations

Fig 15- 5 The canals often line up along an isthmus in the shape of a C pointed toward the buccal

Fig 15 - 4 When a tooth demonstrates the C- shaped canal morphology (a ), often the contralateral tooth has a similar configuration ( b ).

aspect.

Fig 15-6 CBCT imaging provides unique visual insight into the dynamic canal configuration of a tooth with C- shaped anatomy. A C-shaped configuration is shown in the axial scan view.

Fig 15 - 7 A true C- shaped canal configuration. The contiguous canal orifice forms a C. Note the sodium hypochlorite soaking in the canal space.

Fig 15- 8 A C-shaped Fig 15- 9 A pulpal floor with symmetric Fig 15-10 An unusual C-shaped tooth with one canal orifice configu- mesial and distal canal orifices, symmetric mesial and distal canal orifice. ration with separate mesial and distal canal orifices characterized by a semicolon shape.

(Fig 15 -9). Less frequently seen is a configuration with a single symmetric mesial and distal canal orifice (Fig 15 -10). The clinical chamber anatomy of C-shaped maxillary molars tends to be similar to their " ordinary " max illary counterparts. Radiographically, however, C -shaped maxillary molars tend to exhibit the typical root fusion

Preoperative Periodontal Considerations Pulp sensibility tests coupled with radiographic visualization of the periradicular areas establish an accurate pulpal and periradicular diagnosis. It is equally import-

that is ubiquitous in C-shaped teeth.

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Access

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Fig 15-11 An isolated periodontal probing on the distal or mesial surface can often suggest a vertical root fracture.

Fig 15-12 A vertical root fracture in the tooth shown in Fig 1511 was confirmed with a dental operating microscope.

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Fig 15-13 (a and b) A small access is started in the middle of the tooth and expanded only as much as neces sary for instrumentation of the canals. Note that it was not necessary to remove the entire roof of the chamber, (c) One-year follow up.

ant to evaluate the periodontal status during the initial clinical examination. Because of the difficulty of performing effective endodontic treatment on teeth with the C-shaped configuration, extraction may be indicated for teeth with moderate to advanced periodontal disease.

Once the decision is made to initiate endodontic treatment, the clinician must carefully plan an ideal endodon-

For teeth that present with a sinus tract or a deep iso lated probing, the clinician must identify whether these manifestations are primarily endodontic or periodontal in origin or if the tooth is fractured. It is the author's experience that isolated distal probings of greater than 4 mm suggest a vertical root fracture in a tooth with a C-shaped configuration, because sulcular sinus tracts tend to form to the buccal aspect rather than the distal or lingual surfaces (Fig 15-11). A broad distal probing may indicate cratering of bone associated with generalized periodontal disease or bone loss from a previously extracted third molar. A deep lingual probing or sinus tract is not a common occurrence and is suggestive of bone loss due to a lingual developmental groove or vertical root fracture. The author has observed a more frequent rate of vertical root fractures in mandibular second molars with C-shaped configurations than with "normal " second molars with diverging roots. If a fracture is suspected, probe firmly at the distal tooth surface, under local anesthesia if necessary, to ascertain an accurate probing value. Probing values greater than 4 mm should be evaluat ed carefully through an endodontic access with a dental operating microscope (Fig 15 -12). In most cases, if there is a crack that extends down an axial wall and into a canal orifice, the tooth should be extracted.

tic access. The pulp chamber is usually well centered in the occlusal table, so access is initiated toward the center of the tooth (Fig 15 -13). Specialized burs may be used to penetrate or remove existing restorative materials. Most or all of the restorative material should be removed; if a crown is present, a large portion of the occlusal surface can be removed because it contributes little to the overall strength of the tooth. Once the dentin is uncovered, the access should be made in such a way that the structural integrity of the remaining tooth structure is maintained as much as possible. Access is made into the pulp chamber with a small surgical length # 2 round bur (SS White) or an Endoguide EG -1 bur (SS White). Once an opening into the pulp chamber has been created, a broad sidecutting bur such as a tapered diamond bur or an Endo Z bur (Dentsply) is useful for straightening the access, smoothing the vertical walls, and creating a comfortable amount of opening. Be aware of the orientation of the access burs at all times, because there is a tendency to extend the access too far toward the distal aspect, particularly in second mandibular molars when the patient has limited opening. It is easy to mistakenly identify a distal canal as a mesial canal. A working-length radiograph is often a good idea to orient yourself once the first canal is identified. Teeth with

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Clinical Management of C-Shaped Canal Configurations

Fig 15-14 Teeth with the Cshaped configuration sometimes exhibit a deep chamber. In this case, the pulpal floor was more than halfway down the tooth from the coronal aspect of the occlusal table. This makes canal detection even more difficult with limited visibility.

Fig 15-15 (a to c) In this retreatment scenario, the tooth was accessed, a fiber post was removed, and the canals were negotiated to the terminus. A calcium hydroxide interim dressing was placed as an added disinfection step.

Fig 15-16 (a to c) This mandibular left second molar presented with a large preoperative radiolucency and a necrotic pulp. Calcium hydroxide interim medication was changed bimonthly over a period of 8 months. At that point, deep probings were reduced and there was clear evidence of radiographic healing, so the tooth was obturated and restored.

the C-shaped configuration often have deep pulp chambers. This may further complicate locating the canal system (Fig 15-14).

The author has observed that the point of negotiation into the mesial canals tends to be constricted and broader in the distal root. The initial points of negotiation should be identified at both ends of the C, and then the clinician can carefully dissect away the tissue space in between to see if there are additional points of

negotiation.

Instrumentation The cross section of canal systems in teeth with the C-shaped configuration tends to be ribbonlike rather than round or ovoid. There are often transverse anastomoses between canals that make effective debridement and disinfection difficult. Negotiation and instrumentation of canals should be carried out carefully with generous irrigation. The author generally uses the following

1. Clean the chamber and identify the full extent of the C-shaped groove. 2. Lightly trough the full length of the groove with a small round bur or round-tipped ultrasonic tip. Debris will pack into the groove and show areas of widening that are potential entry points. 3 Using small hand files with light pressure, attempt to negotiate all the potential canals. 4. Carefully enlarge the canals with hand files and small rotaries. Aggressive preparation with Gates Glidden burs or large nickel-titanium rotary files is not recommended. Teeth with C- shaped configurations are more susceptible to strip perforation, so small files with small tapers are preferred. 5. At some point in the process, establish patency for all canals if possible, and maintain it throughout the

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remainder of the procedure. 6. Use small precurved files by hand or with sonic or ultrasonic activation to carefully debride the isthmus es. This should not be done aggressively.

protocol:

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Restoration

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Fig 15 -17 (a and b ) This unique mandibular left second molar exhibited a C-shaped anatomy with an extra fused mesiobuccal root, (c) For tooth-preservation purposes, this root was accessed independently from the main C- shaped canal system, even though they shared a mutual pulp chamber, (d and e) Instrumentation and obturation were performed through two access cavities, (f and g ) The tooth was restored with bonded composite.

gutta-percha in the apical third but are "slim fitting" at the coronal third, so they do not tend to bind in the

Interim Calcium Hydroxide Dressing

coronal two-thirds of the canal. 2. Try to obtain tugback in the fully seated cone. Sometimes this is more difficult in teeth with a C-shaped configuration because of the ribbon shape of the canal system. 3. If there is a significant space lateral to the seated cone, then additional cones can be placed to fill the space or a bolus of thermoplasticized gutta-percha can be injected into the space prior to the downpack. 4. Perform multiple downpacks and backfills to force gutta -percha and sealer into the fins and isthmuses.

Calcium hydroxide paste has favorable antimicrobial properties and aids in dissolution of residual tissue not removed during instrumentation. Because of the inaccessible areas in fins and isthmuses, the author almost always treats these teeth in multiple appointments with a calcium hydroxide interim dressing (Fig 15-15). This additional clinical step also allows assessment of the initial treatment to ensure that symptoms and clinical signs resolve before the canals are obturated and the tooth is restored (Fig 15-16).

Restoration

Obturation

As with all endodontically treated teeth, immediate restoration is desirable to prevent contamination and pro tect the remaining tooth structure. Bonded restorations are preferred (Fig 15-17). Posts are rarely indicated in molars, but in those cases where a post is necessary, there are special considerations with a C-shaped configuration. In most mandibular mo lars, posts are placed in the distal canal because it is the largest, straightest canal. In teeth with a C-shaped configuration, the distal canal is sometimes ribbon-shaped and provides poor retention. In these situations, consid-

C-shaped teeth present a special set of challenges during the obturation phase. The primary challenge is volumetric: The canal system is highly irregular, but most obturation techniques utilize round, standardized gutta-percha cones and sealer. Based on years of experience, the author has developed the following obturation technique: 1. Fit a gutta-percha cone that corresponds to the taper used to prepare the canals. Autofit cones (SybronEndo) work well because they maximize the volume of

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Clinical Management of C-Shaped Canal Configurations Fig 15-18 (a and b) This abutment tooth for a partial denture had little mesial tooth structure but an adequate canal. Therefore, a fiber post was bonded into the mesiobuccal canal to help retain the build-up restoration.

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Fig 15-19 (a) The initial endodontic treatment was failing, (b) Upon access, the author located an untreated canal, and there was necrotic tissue evident in the isthmuses between the canals, (c to e ) Retreatment was completed.

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er a carefully placed post in the mesiobuccal canal (Fig 15 -18), if it is independent and will create the best friction fit. In most cases, the pulp chamber and canals provide adequate retention so that a post is not necessary.

should be used in combination with solvents. This process can be tedious (Fig 15-20). Create channels through the filling material as a starting point for instrumentation and for solvents to facilitate the process. The au-

thor prefers removal of root- filling material at the orifice level using a CT- 4 or UT- 4 ultrasonic tip (Excellence in Endodontics) at a low power setting. Precurved stainless steel K-files and Hedstrom files, sizes no. 15 to 25, can be used to scrape adherent material from the canal walls and isthmuses. Continually irrigate with chloroform. Use sonic or ultrasonic activation to move the filling material into suspension, where it can be absorbed onto paper points or flushed out with copious chloroform solvent into an assistant's suction. Retreatment of teeth with a C -shaped canal configuration can be tedious and challenging because the clinician must work within the anatomical limitations imposed by each unique canal system (Fig 15 -21).

Retreatment If an endodontically treated tooth with C -shaped anat omy appears to be failing, then nonsurgical retreatment is often preferred due to issues with access and rootend preparation. Often a contributing factor to refractory endodontic disease is untreated canal space in the C-shaped anatomy, which may harbor necrotic tissue or debris (Fig 15-19). When retrieving root - filling material, care must be taken not to overenlarge the existing canals because of the risk of strip perforation. Small instruments and hand files 154

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References

with Fig 15 - 20 (a to d ) A considerable amount of gutta-percha root-filling material was carefully removed from this broad, fanning C-shaped system a no. 20 Hedstrom file and a precurved no. 25 K-file, used in alternating fashion with chloroform solvent.

Fig 15- 21 (a ) This C- shaped tooth was retreated due to the presence of a periapical radiolucency coupled with acute symptoms, (b) A stainless steel parapost was removed, (c and d ) Retreatment was completed over a period of 6 weeks, (e) The 2-year recall radiograph shows evidence of complete healing.

References

Summary

1. Barnett F. Mandibular molar with C-shaped canal. Endod Dent Traumatol 1986;2:79-81. 2. Chai WL, Thong YL. Cross-sectional morphology and minimum canal wall widths in C-shaped roots of mandibular molars. J Endod 2004;30:509-512. 3. Manning SA. Root canal anatomy of mandibular second molars. Part 1. Int Endod J 1990;23:34-39. 4. Yang ZP, Yang SF, Lin YC, Shay JC, Chi CY. C-shaped root canals in mandibular second molars in a Chinese popula tion. Endod Dent Traumatol 1988;4:160-163.

Teeth with a C-shaped canal configuration are most commonly seen in the mandibular second molar position but may occur in other locations. Their conical, fused root forms usually allow them to be identified radiographically. They vary in shape and intracanal morphology and provide a clinical challenge for endodontic treatment. This treatment is often fraught with danger and requires conservative, even delicate handling. This chapter has provided guidance for safe clinical management.

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PART IV

Retreatment

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CHAPTER

16 Fred S. Tsutsui, DMD Robert H. Sharp, DDS

Bypassing Ledges, Separated Instruments, and SillfKlMiE

Endodontic treatment and retreatment can be very challenging. This is especially true when obstructions are present. Obstructions are usually iatrogenic in nature, such as ledges, blockages, and separated instruments that occur during initial treatment, but they can also occur due to natural calcifications. This chapter discusses how to prevent obstructions as well as strategies to treat them when they occur. Clinical management of obstructions requires specific skills that are somewhat different from those employed for standard endodontic procedures. Successful treatment requires an understanding of root canal anatomy and what causes obstructions as well as knowledge of how to use specific armamentaria. In recent years, focused-field cone beam computed tomography (CBCT) technology has become an important asset in managing obstructions. Obstructions prevent access to the apical portion of the canal for debridement and disinfection. In most cases, the goal of treatment is to remove the obstacles (ideally) or bypass them. When neither goal is achievable, obturating to the obstruction ( and observing), apical surgery, and extraction are the remaining treatment options.

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m Bypassing Ledges, Separated

Instruments, and Other Obstructions

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Fig 16-1 A ledge was created by a Gates Glidden bur (a) and subsequently made worse with a Fig 16- 2 A ledge led to a straightened canal rotary file (b). and perforation.

Fig 16- 3 fa) A small, sharp apical bend is placed with a bird beak pliers or similar instrument, (b ) A properly precurved hand file will tend to deflect off the ledge and advance apically.

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Bypassing or Removing a Ledge

1. Visualize the curvature of the canal, the location of the ledge, and the path necessary to bypass it. 2. Use small hand files that are precurved (Fig 16-3). 3. Use plenty of irrigation with sodium hypochlorite. Avoid ethylenediaminetetraacetic acid (EDTA) until

Ledging usually results when an instrument is forced against the outer curvature of a canal wall. Once a ledge has been created, subsequent rotary or hand files can compound the problem by enhancing the ledge and straightening the canal, making the ledge progressively more difficult to bypass. Figure 16-1 shows the creation of a ledge with a Gates Glidden bur (Fig 16-1a) and subsequent deepening of that ledge by a rotary instrument (Fig 16-1b). Figure 16- 2 shows the straightening effect that can result in a perforation. The best way to deal with ledges is to avoid them in the first place by following a few basic principles:

the ledge is bypassed.

4. Once the ledge is bypassed, use many short in-out filing motions in an anticurvature direction to try

smooth out the ledge before withdrawing the file from the canal. This will facilitate bypassing the ledge with subsequent hand files. Hedstrom hand files are effective for smoothing out a ledge. 5. Once the initial instrument fits loosely in the canal, try the next- larger file in the same manner. 6. Once a proper glide path has been established with hand files, introduce small, precurved rotary instruments. 7. In most cases, rotaries can be used to finish the job. to

•Visualize the curvatures as much as possible from ra-

diographs and CBCT and precurve files before inserting them into the canal •Use light forces. •When an obstruction is encountered, back off and try to find a path around it. •Use instruments with noncutting tips.

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Removing a Separated Instrument

Clinical procedure

Separated instruments are usually the result of operaRarely are separations due to a manufacturing defect. The most common causes are overuse and/or

tor error.

The clinical procedure for bypassing a ledge is as follows:

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Removing a Separated Instrument

Fig 16- 4 (a ) An instrument was separated in the mesiobuccal canal (arrow ), (b) Under

high magnification of the operating microscope, space is visible on the side of the instrument segment . (c) The instrument handle was requested and received from the original treating dentist. An SP - 3 ultrasonic tip (SybronEndo) was applied to the instrument for 1 second at high power, (d ) The separated instrument immediately loosened and jumped out of the canal, (e) Treatment was completed uneventfully.

excessive forces exerted by the operator. Rotary instruments in particular are susceptible to breakage when the tip gets caught in an isthmus or confluence of two canals. As with ledges, prevention is the key. To prevent separation, follow these guidelines:

•Single-patient instrument usage is a good policy. Hand and rotary instruments should be discarded once the treatment has been completed. Use a light touch. Never force an instrument.

•

•Use plenty of irrigation.

•Aggressive instruments with cutting tips are more sus-

ceptible to separation as well as ledging and other problems. •When an instrument binds, back off, irrigate, precurve if appropriate, and reinsert. •Use instruments as passively as possible. •Use special care in tight canals, sharp curvatures (particularly in the midroot area), and S-curves. S-curves and curvatures in the midroot are especially dangerous with rotary instruments when the thicker, less flexible part of the instrument engages the mid-root curve. •Some rotary instruments are "grabby" when they bind in the canal, which can result in the operator losing control of the instrument and it being " pulled in."

Knowledge of the brand and flute design of the separated instrument can be helpful. Retain or obtain (if possible) the handle portion of the instrument for later reference. If the handle portion is unavailable, request information about the type of instrument that separated. Knowing the flute design and gauge of the instrument can help to select a strategy for its removal.

Clinical procedures Direct and indirect ultrasonics Sometimes an instrument separates when the tip is caught in a fin or irregularity in the canal. If the head of the segment can be visualized with the dental operating microscope, it can usually be removed. A clean, dry canal is needed to assess the situation. Irrigate the canal with sodium hypochlorite, scrub the walls, and use sonic or ultrasonic agitation. Do a final rinse with 100% alcohol and dry the canal with a Stropko irrigator (SybronEndo). Close examination under the microscope may reveal a gap or space between the instrument and a canal wall (Figs 16-4a and 16- 4b). A thin ultrasonic spreader tip (such as the SP-3 tip, SybronEndo) can sometimes be inserted into the gap and activated, causing the file to loosen and sometimes " jump " out of the canal (Figs 16- 4c to 16-4e). Activate the tip at high power for only 1 second at a time. Prolonged use (more than 1 second) can result in several negative outcomes, such as overheating, excessive dentin removal, or breakage of the instrument segment or ultrasonic tip. If the instrument segment is not dislodged af ter several attempts in a dry canal, place the ultrasonic tip against the instrument, flood the canal with water, and repeat with several short ultrasonic bursts. The water acts as a lubricant and coolant and will often expedite the process. Sometimes indirect ultrasonics work best in delicate roots or areas with difficult access. This technique ap plies ultrasonic energy to an endo explorer or spreader, which is used to contact the instrument segment inside

the canal.

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Bypassing Ledges, Separated Instruments, and Other Obstructions

Fig 16- 5 The IRS System utilizes a tube with a Fig 16- 6 (a and b ) The Cancellier System utilizes a hollow tube that fits on a handle. The tube solid shaft inside to retrieve instruments or oth- slips over the head of the separated instrument, and super glue is used to secure and retrieve the er objects from canals. The tube slips over the instrument. (Courtesy of Dr Gary Carr, San Diego, California.) end of the object, the head of the object slides out a window near the end of the tube, and the object is secured between the shaft and wall of the tube.

Fig 16-7 Assorted tubes.

Tube / cannula techniques

spreader, if possible, to create space. If this cannot be accomplished and there is sufficient dentin wall thick ness, remove some dentin with a thin ultrasonic tip at the contact point. If the handle portion of the instrument is available, find the smallest tube that loosely fits over the broken end. The loose fit allows room for the composite material when you slip the tube over the exposed end of the file. The clinical procedure is as follows:

If the top of the instrument is visible and accessible, and repeated attempts with the ultrasonic tip are unsuccessful, another approach is to use a tube or cannula. There are a number of commercial instrument removal systems available, such as the IRS system by Dentsply Tulsa Dental (Fig 16-5), the Cancellier Instrument Removal System by SybronEndo (Fig 16-6), and the Endo Extractor System by Roydent. The authors have used all of these systems with varying degrees of success. A simple and more economical cannula /tube method utilizes the " tube and glue" technique with selfcuring composite. Tubes of different gauges are shown in Fig 16-7. The authors have used dead soft tubes from Ultradent Products and Vista Dental Products. The coronal end of the separated instrument segment must be exposed 2 to 3 mm with a circumferential space around it with the tube and glue technique. If the head of the instrument is leaning against a canal wall, it must be teased to the center of the canal with an explorer or

1. Clean and dry the canal as previously described. 2. Mix a small amount of self -curing or dual-curing composite. 3. On a mixing pad, scoop composite into the end of the prefit tube and place it over the exposed portion of the separated instrument. 4. Wait for the excess composite on the mixing pad to harden. If you are an impatient person, leave the room. 5. Grasp the tube/cannula, pull gently, and unscrew the

file (counterclockwise for most files).

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Removing a Separated Instrument

Fig 16- 8

(a ) A separated hand file is shown in a multicanal mandibular premolar (arrow ). The handle portion of the instrument was obtained and used to gauge the appropriate tube size, (b ) Self - curing composite was scooped into the end of the tube and placed around the exposed portion of the instrument, (c and d ) After 5 minutes of curing time, the tube was removed with the separated instrument inside, (e) The case was then completed.

Fig 16-9 (a ) An instrument was separated deep in the mesial root of a mandibular molar (arrow ). A tube was fitted loosely over the head of the separated instrument, and a Hedstrom file was screwed into the space between the file and the tube wall. The instrument was engaged and removed (b), and treatment was completed (c ). (Courtesy of Dr Rebecca Prescott, San Antonio, Texas.)

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The lasso technique utilizes a tube and thin ligature wire. The tube carries the wire loop into the canal, and the wire “lassos" the head of the instrument or other object and removes it. In this case, a silver point was removed. to c)

The separated instrument generally comes out with ease. The tube and glue technique is illustrated in Fig 16- 8. The “tube and Hedstrom " technique is somewhat similar to the tube and glue technique. The head of the separated file segment is exposed, and a loose-fitting plastic or soft metal tube is slipped over the head. A small Hedstrom file is screwed into the gap between the file and tube wall. The file is engaged and removed (Fig 16-9).

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The “ lasso " technique utilizes a loop of thin ligature wire in a tube. It can be effective to remove separated instrument segments, silver points, and metal carriers. The tube carries the wire loop into position. The ligature is looped around the head of the obstruction and cinched tight at the other end of the tube, and the obstruction is removed (Fig 16-10).

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Bypassing Ledges, Separated Instruments, and Other Obstructions

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a Fig 16-11 A separated instrument was successfully bypassed despite the sharp curvature in the mesiobuccal canal, (a ) Preoperative view prior to file separation, (b) The separated instrument was bypassed with a small file, (c) Completed treatment. (Courtesy of Dr Venkat Canakapalli, Tauranga, New Zealand.)

Fig 16 -12 (a and b) An instrument was separated in a sharp curvature in the mesial root of the mandibular right third molar (arrow ), (c) It was bypassed successfully and obturated, (d) The 14 - year recall radiograph.

4. If the isthmus area does not work, try other areas. In many cases, there is at least one path that can be negotiated past the instrument segment. 5. Once the hand file starts to advance, you will be able to reinsert the subsequent files blindly into the correct path. Repeat the process with the canal flooded with sodium hypochlorite. Remember to be patient; it may take a number of files to bypass the instru-

Bypassing an Instrument Segment There are several techniques to partially or totally bypass the instrument segment. Some clinicians believe that this is a better option than removing the instrument segment because very little dentin is sacrificed in the process. The process of bypassing an instrument segment starts with small hand instruments (often many). It can be a slow and tedious process and requires that the operator understand the anatomy of the canal. CBCT imaging can provide information about canal curvatures in three dimensions, the location of the separated instrument, and additional information about the canal anatomy, such as whether canals merge. A dental operating microscope is

ment segment.

6. Once the instrument segment is bypassed, carefully repeat the process with successively larger hand files. Irrigation with EDTA is helpful at this point. 7. In many cases, the canal can be fully instrumented once the instrument segment is bypassed. Rotary files should be used cautiously so the canal does not end up containing two broken instruments. 8. In some cases, the separated instrument comes out in the process of preparing the canal. 9. A small file in an ultrasonic handpiece can be used to try to loosen the instrument once it is bypassed, allowing it to be removed. There is some danger to this approach, however, because the instrument segment can be pushed apically once it is loose.

paramount to success. In many cases, with patience, the instrument can be

bypassed with small, stiff hand files. The best place to do this is often adjacent to an isthmus. The clinical procedure is as follows: 1. Some clinicians believe that bypassing an instrument segment is a better option than removing it because very little dentin is sacrificed. 2. Clean and dry the canal as previously described. 3. Visualize the instrument, if possible, and attempt to insert a size 6 or 8 hand file between the instrument and isthmus, feeling for a "catch." Gently try to advance with a watch- wind motion.

Separated instruments were successfully bypassed under difficult circumstances in Figs 16-11 and 16-12.

The braiding technique The "braiding" technique also bypasses the instrument segment but with the intent to remove it. Small hand files may

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Removing Nonspecific Obstructions

Fig 16-13 (a to d ) A separated instrument (arrow in a) was bypassed on two sides, hand files were inserted and braided around it, the file was removed, and treatment was completed.

tions are usually the result of a lack of understanding about proper canal instrumentation, or impatience, and can be avoided by following a few basic principles:

be used as previously described to bypass the segment. For short instrument segments that are loosely wound, a file can sometimes enter the flutes and bypass the instrument. In this situation, the tip of the hand file will come out of the canal in a spiral shape that follows the flutes of the separated instrument. This technique was refined and taught by Dr David Rosenberg, who trained many clinicians in its use. The clinical procedure is as follows:

•Start with small hand files and use them passively as

much as possible. •Irrigate extensively. •When resistance is encountered, never force an instrument.

1. Clean and dry the canal as previously described. 2. Evaluate the access preparation to see if better ac cess can be attained. 3. Try to create a " stick " adjacent to the instrument segment with an endo explorer or fine spreader. 4. Try to engage the stick with a small hand file. If you cannot, create a stick in a new location. 5. As the file starts to advance, use C+ files in a 6, 8, 10, 6, 8, 10 . . sequence. Irrigate with EDTA once the instrument is bypassed. You must be able to bypass the entire separated instrument. When a no. 10 file easily bypasses the separated instrument, continue to sizes 15 and 20 K-files. 6. Pry the other side of the separated instrument away from the contacting wall with an explorer or spreader, and then repeat the sequence of 6, 8, 10 as be fore. The goal is to bypass the separated piece inside another flute or create a second path around the outside surface. 7. Place a no. 20 hand file, preferably a Hedstrom file, on one side of the separated instrument and a no. 10, 15, or 20 file on the other side. 8. Braid the two files counterclockwise and rotate and lift the separated piece out of the canal (Fig 16-13).

•Be patient. •Establish and maintain patency. Frequent recapitula tion helps prevent iatrogenic blockages.

Bypassing canals blocked with debris The clinical procedure for bypassing canals blocked with debris is as follows:

.

1. Place sodium hypochlorite in the canal and allow it to " soak " for 5 minutes in an attempt to dissolve the organic components and loosen the knot of debris. 2. Carefully use precurved hand files (see Fig 16-3), sizes 6, 8, and 10, to break up the blockage and allow

canal irrigants to flush out the debris. 3. It is crucial to find the " soft spot " to disrupt or bypass the blockage. Usually a debris obstruction is only 0.5 to 1.0 mm thick and densely packed at the coronal side. 4. Once a soft spot is found, use hand files in a balanced-force manner to efficiently penetrate the looser interior of the obstruction. 5. Once the obstruction is bypassed, routine file sequences can be employed. 6. Recapitulation with patency files is crucial to prevent recurrence of obstructions. 7. Forceful disruption of the blockage should be avoided to prevent " straightening out " of the canal and creation of a ledge or lateral root wall perforation (Fig 16-14). A passive, gentle "pecking " motion into the obstruction should be used.

Allow 2 or more hours if this is your first attempt.

Removing Nonspecific Obstructions term "blocked out " of the canal may refer to obstructions of natural calcific material or may be caused by previous endodontic procedures. Iatrogenic obstruc -

The

When hand files are unsuccessful, try ultrasonics. An ultrasonic file adapter can be used to attach a no. 10 hand file to an ultrasonic handpiece. Fill the canal with

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Bypassing Ledges, Separated Instruments, and Other Obstructions

Fig 16-16 A light acoustical stream of water is shown coming off an ultrasonic file.

Fig 16 - 14 A plastic block with an Fig 16-15 Ultrasonic file adapters obstruction demonstrates how a (SybronEndo). canal can be straightened out via forceful instrumentation.

Fig 16- 17 (a ) A molar was referred for retreatment (b) All materials were removed from the canal to the point of the obstruction. A no. 8 hand file would not go beyond the obstruction, (c and d ) A precurved ultrasonic file was used at low power with water, which broke up the obstruction. All canals were negotiated to the apices (arrow ) (e), and treatment was completed (f ). ,

sodium hypochlorite and activate the ultrasonic file. In some cases, this agitation will loosen the blockage. Ultrasonic file adaptors are available through SybronEndo (Fig 16-15) as well as Osada. There is no reason to use a file larger than a size 10. Use ultrasonic files passively. To work effectively, the file tip should not engage the canal walls. Aggressive use can cause file breakage, unnecessary dentin removal, ledging, or perforation. The technique for using the ultrasonic file is as follows:

7. Once the obstruction is bypassed, treatment can usually be completed in the usual manner (Fig 16-17). 8. If no further advancement into the canal occurs with the small hand files, repeat the ultrasonic activation. 9. Repeat the process until the blockage is removed or your attempts exceed 1 hour. Be patient and avoid excessive force with the ultrasonic file.

If unsuccessful with either approach, calcium hydroxide can be placed in the canals for a minimum of 2 to 3 weeks. Calcium hydroxide has tissue-dissolving properties. Sometimes an obstruction can be bypassed at the second appointment. If bypassing is ultimately unsuccessful, alternative options include obturating to the level of the obstruction followed by observation, apical surgery, or extraction.

1. Remove all obturating materials to the level of the obstruction and clean the canal as previously

described. 2. Set the ultrasonic unit at the lowest power setting

with the water on. 3. Precurve the file in the adapter with a gentle curva ture (see Fig 16-17c). 4. Avoid contact of the ultrasonic file with the canal

walls.

5. Use a gentle pecking motion. You will see a light

Summary

acoustical stream of water coming off the file from the ultrasonic energy (Fig 16-16). 6. After 15 to 20 seconds of gentle pecking, re-enter the canal with small hand files and follow the procedure as previously described. If a tugging or binding of the ultrasonic file occurs before 15 seconds, stop the ultrasonics and switch to hand files.

This chapter has outlined strategies and procedures for the clinician to efficiently and conservatively treat ledges, instrument separation, and obstructions. It has also provided the reader with a better understanding of the etiologies that create these problems and how to prevent them from occurring.

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CHAPTER

Marga Ree, MSC, DDS

Removing Metal

Retreatment sometimes requires post removal to gain access to the root canal system. Post removal should only be considered when there is sufficient remaining tooth structure so the tooth can be restored predictably. The structural integrity of the remaining tooth structure is one of the key factors for long-term survival of the tooth. There are several factors that influence the difficulty of post removal:

•Type of luting cement •Post length •Adaptation of the post to the canal wall •Use of magnification and specific devices

•Expertise of the clinician

•Composition, shape, and surface texture of the post Posts come in a variety of materials, designs, and shapes, and their removal requires a variety of techniques and instruments Therefore, it is important to identify which type of post was used. Posts can be fabricated from stainless steel, gold, nickel- chromium alloy, titanium alloy, ceramic, zirconia, and fiber-reinforced composite (FRC). Metal posts can be passive or active, which may also influence the choice of the device that will be used for post removal.

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Post Identification In general, the radiographic appearance of the post can help the clinician to identify its material composition and its design (active versus passive) (Fig 17-1). The most radiopaque post systems are cast post and core systems and stainless steel posts, followed by posts made out of zirconium diox ide (zirconia). Titanium posts are sometimes difficult to distinguish radiographically, because their radiopacity is similar to that of gutta - percha. Most FRC posts are relatively radiolucent and may be outlined by more radiodense luting cements.

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Removing Metal and Fiber Posts

Fig 17-1 Radiographic appearance of different post systems: (a ) custom cast metal post; (b ) threaded metal post; (c) zirconia post; (d) titanium post; (e) FRC post.

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US Fig 17- 2 Munce Discovery Burs.

Fig 17- 3 EndoGuide burs.

piece. Once there is minimal restorative material left, a less aggressive rotary instrument, such as a Munce Dis covery Bur (CJM Engineering) (Fig 17-2) or EndoGuide bur (SS White) (Fig 17-3), or an ultrasonic tip can be used. The goal is to free the head of the post from restorative material while limiting the loss of sound tooth structure and thinning of the post. The more of the post head that is exposed, the greater are the options for removal. Once enough of the post has been exposed, the retrieval procedure can be carried out.

Removing Metal Posts In most cases, metal posts can be removed effectively and safely. Post removal should be carried out under rubber dam isolation to optimize visual control, prevent contamination, and protect the patient 's airway. The use of an operating microscope significantly facilitates the

procedure.

A variety of techniques and instruments for metal post removal have been developed. These include burs, trephines, ultrasonic devices, and mechanical post extraction devices. In general, when rotary instruments are used to remove a metal post, sound root dentin is sacrificed, which weakens the tooth; therefore, rotary instruments should be avoided as much as possible when removing posts. Ultrasonic vibration is an effective way to break down the luting cement and will eventually result in loosening of the post from the root canal in most cases. If properly used, this technique presents suitable

Removing a threaded metal post To remove threaded posts, grasp the exposed head with a small forceps or thread on an extractor device and gently turn it in a counterclockwise direction (Fig 17 -4). If the post does not rotate initially, apply an ultrasonic tip in a counterclockwise rotation to help break down the cement, and then try to rotate it again. Avoid excessive rotational forces that could crack the root or break off the head of the post. Once the post has been removed, a careful inspection of the root should be carried out to

efficiency, speed, and safety while preserving the root integrity. Ultrasonic energy causes heat generation and should always be carried out with water spray. In most cases, if the post has not loosened after 5 to 10 minutes, other methods should be considered. No matter which technique is utilized, the first step is to create sufficient access to the post by removing all adjacent restorative material. Gross removal can be accomplished with diamond burs in a high-speed hand-

evaluate the integrity of the remaining root structure, look for cracks, and assess the restorability of the tooth.

Removing a passive metal post Ultrasonic energy may be used to break the cement bond and ultimately loosen the post. The effectiveness

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Removing Metal Posts Fig 17- 4 (a ) The mandibular right premolar has to be retreated for restorative reasons, (b ) After re moval of the core material on this mandibular right premolar, the head of the threaded post is adequately exposed, (c) Ultrasonic vibration is applied to the post, (d to f ) By turning the forceps in a counterclock wise direction, the post is removed from the canal.

Fig 17- 5 (a ) CPR -1 ultrasonic tip (SpartanObtura). (b) CPR - 1 ultrasonic tip used for post removal.

Fig 17- 6 (a) Preoperative radiograph of a mandibular left first premolar before post removal and retreatment. Water spray was not used for cooling, and excessive heat was generated during the post removal procedure, (b) Intraoral photograph taken approximately 1 month later. The soft tissue adjacent to the tooth is necrotic , (c) Radiograph taken shortly before extraction shows necrosis of the alveolar bone.

of ultrasonics is dependent on ( 1 ) the composition and volume of the post and (2) the type of cement. Long, deeply embedded posts with close adaptation to the canal wall can be very resistant to ultrasonic vibra tion and require extra time to break down the cement. It is the author's experience that most stainless steel and cast gold posts can be vibrated loose in 5 minutes, and even the most difficult ones can usually be loosened in less than 10 minutes. Removal of titanium posts may take longer, because they have a low modulus of elasticity (stiffness) compared with stainless steel. A material with a high modulus of elasticity transmits ultrasonic energy more efficiently than a material with a low modulus. Metal posts

Fig 17-7 Stropko irrigator (SybronEndo).

cemented with resin cements also generally require more time for removal than those cemented with glass ionomer or zinc phosphate cements The ultrasonic tip (Fig 17-5) is applied to the post at a high setting in an up-and- down and circumferential man-

.

ner with minimal pressure and sufficient coolant. Often there is a " sweet spot " where the ultrasonic energy is transferred most effectively to the post. Ultrasonic energy applied to metal objects can generate high temperatures on the root surface and in the surrounding bone, which in extreme cases can result in necrosis and tooth loss (Fig 17-6) Use of the Stropko irrigator (Fig 17-7) by the dental assistant will keep the working field free of debris and greatly facilitates the procedure.

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Removing Metal and Fiber Posts

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Fig 17 - 8 (a ) Preoperative radiograph of a maxillary right central incisor with a cast post and core, fb) The patient was not satisfied with the appearance of the metal-ceramic crown and desired to have the crown replaced by a nonmetal restoration. Note the dark appearance of the marginal gingiva, probably

caused by the metal substructure of the crown and post (c) A slot is prepared in the palatal surface for a crown remover, (d) The crown remover is applied, (e) After removal of the crown, the cast post and core is exposed, (f ) The cast post and core is isolated with rubber dam and reduced in diameter, ( g ) An EndoGuide bur # 4 in a high - speed handpiece is used to dissect the cement layer around the post. (h) A CPR - 1 ultrasonic tip is used to apply ultrasonic vibration to the post, ( i ) The post is removed, ) (j After post removal, there are remnants of cement attached to the canal walls, ( k ) All remaining cement residue from the canal walls is removed. (I and m ) An apical plug of mineral trioxide aggregate (MTA) is applied, ( n and o ) The existing post and crown are used as a temporary restoration, (p ) Postoperative radiograph showing the endodontically retreated root canal and an FRC post and core, (q and r ) Recall radiograph and clinical photograph after 1 year, showing the definitive restoration. The gray appearance of the marginal gingiva has improved but not fully disappeared. ,

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After removal of the post, all remaining cement residue from the canal wall should be removed with an endo explorer or fine ultrasonic tip. Finally, the remaining tooth structure

be examined carefully to verify its structural integrity and the absence of any cracks, fractures, or perforations. The clinical procedure is shown step by step in Fig 17-8. must

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Removing Metal Posts Fig 17- 9 (a ) The Gonon Post Removal Kit (Schwed) . (b ) By turning the wheel of the post puller in a clockwise direction, an extraction force is created.

Fig 17-10 (a ) Preoperative radiograph of a maxillary right central incisor with an apical radiolucency requiring removal of the titanium post and endodontic retreatment . (b) The tooth is isolated with rubber dam. (c) The core is reduced into a roughly cy lindric shape, (d ) A Munce Discovery Bur is used to create a trough around the post . (e) A trephine bur is used to mill the coronal part of the post to the proper size, (f ) A mandrel is used to tap a thread onto the head of the post , (g ) The Gonon post puller in place and ready to use. Note the silicone disk used to cushion the tooth from the metal post puller, (h) The wheel is turned to open the jaws and create the extraction force, ( i ) Removal of the post and preservation of tooth structure, ( j ) Postoperative radiograph showing the root canal filling, FRC post, and definitive restoration.

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the wheel in a clockwise direction, which opens the jaws and creates shear forces on the cement. Most cements have weak resistance to shear forces. The tooth should be protected from the post puller by using one or more silicone disks (Fig 17-10). The Gonon-type kits can also be used to remove a threaded post. After the mandrel has been applied to the threaded post, it is rotated continuously in a counterclockwise direction to unscrew the post. The author turns to the Gonon device if ultrasonic application has been unsuccessful after 5 to 10 minutes. The Gonon requires very little removal of tooth struc ture, which is a definite plus, though it is reported to occasionally cause tooth fractures. However, the author has never had that occur when using the Gonon.

Removing a metal post with the Gonon-type post removal system The Gonon post removal system (Dent Corp) was first introduced by Dr Gonon in 1955 and was later modified by Dr P. Machtou (Fig 17 -9). There are several other post removal systems that are similar, and these systems can be used for removal of parallel or tapered passive or threaded posts. Once enough of the post has been ex posed, a trephine bur is used to reduce the diameter of the post to a specific size. Then a corresponding sized, internally threaded mandrel is placed on the head of the post and rotated in a counterclockwise direction to tap the internal threads onto the post. Finally, the extraction device or post puller is applied and activated by turning

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Removing Metal and Fiber Posts

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Fig 17-11 (a) Preoperative radiograph of a maxillary right central incisor with an apical radiolucency requiring removal of the cast post and core and endodontic retreatment, (b ) The tooth is isolated with rubber dam, and the composite core material adjacent to the post is removed with an EndoGuide bur in a high- speed handpiece, (c) An appropriate-size microtube is filled with composite and seated over the exposed post head. The microtube is left in place until the composite is fully set. (d) The microtube is rotated until a path of removal is found, (e) Removal of the post, (f ) Removal of the root canal filling (g ) Intracanal dressing of calcium hydroxide. ,

Removing a metal post with a tube and composite The tube and composite removal technique can be used in conjunction with ultrasonic vibration to the post. Sometimes the cement layer is disintegrated to the point that the post is loose but still will not come out of the canal due to cement retention on the post that binds on the canal wall. In this case, a microtube (Vista Dental) can be used with composite resin to remove the post. An appropriate-size microtube is selected and fitted over the exposed post head, the microtube is filled with a chemical curing composite material and seated over the post, and the composite is allowed to polymerize. The tube can then be used as a handle to remove the post (Fig 17 - 11). This sometimes requires a rotational motion or trial and error to find a path of removal, but it is a good technique to use with an all-ceramic or metalceramic crown where ultrasonic vibration to the post risks damage to the overlying ceramic material.

Removing Nonmetal Posts Removing a fiber-reinforced composite post FRC posts can be successfully removed using burs and ultrasonic tips. The time needed to remove an FRC post is dependent on the composition of the post, its length and location, the type of bur that is used, and the skills of the clinician. For example, carbon FRC posts require less time to remove than glass FRC posts because the material is softer and easier to distinguish from tooth structure ( black or dark gray in appearance). Most manufacturers state that fiber posts are easy to remove. This might be true in vitro, but clinically the procedure can be very challenging. Glass- and quartz based FRC posts are harder to penetrate than carbon fiber posts and are white, which can make them difficult to distinguish from tooth structure. Wetting an FRC post makes it more distinguishable from the surrounding composite and tooth structure.

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Removing Nonmetal Posts

Fig 17 -12 (a) The patient was referred because of a sinus tract at the buccal aspect of a maxillary left lateral incisor, which was an abutment tooth for a three-unit bridge (b) Preoperative radiograph showing an apical radiolucency. The sinus tract is traced with a guttapercha cone. The patient opted for retreatment , which required removal of the FRC post , (c ) The bridge is removed (d ) The tooth is isolated with rubber dam. The post is visible toward the palatal aspect of the canal, (e) The fibers that are embedded in the resin matrix of the post are cut with a bur and removed from the root canal, ( f ) A Munce Discovery Bur is shown in the coronal part of the root canal ( g) A Munce Discovery Bur in the middle part of the root canal. Note that the bur head is getting off track, creating the beginning of a false path. Tilting the bur head in a more distal direction is impaired by the size of the bur shank, fully occupying the small access opening, (h ) An ultrasonic tip (CPR -4 , Spartan -Obtura) is used to remove the last part of the post and the remnants adhering to the canal wall (i ) After removal of the root canal filling, the working length is determined, ( j ) An intracanal dressing of calcium hydroxide, (k ) After 4 weeks, the sinus tract has disappeared. (I ) A new FRC post is placed. ( m) The bridge is recemented, ( n ) A radiograph at 4 years showing a healthy abutment tooth in full function. ,

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Once the head of the post is exposed and visualized, a pilot hole is prepared in the middle and the post is " cored out " internally. Munce Discovery Burs are very

efficient for this task. Their long shanks allow direct visualization under the microscope to a fairly great depth. Once visibility becomes impaired, ultrasonic tips may

be used to penetrate through the apical segment of the post. When in doubt, radiographs should be taken to ensure that the bur or ultrasonic tip is in proper align ment. Once the level of the gutta -percha is reached, any residual fibers and composite attached to the canal wall can be removed using ultrasonics (Fig 17-12).

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Fig 17-13 (a) Preoperative radiograph of a mandibular right second premolar with an apical radiolucency requiring removal of the zirconia post prior to endodontic retreatment (b) An access opening is prepared in the occlusal surface, j and the post is visible, (c) Removal of the post after using ultrasonic vibration, (d) Postoperative radiograph showing the root canal filling with MTA and an FRC post. Note the thin root canal walls due to removal of dentin around the zirconia post, (e) Recall radiograph after 6 months showing that the radiolucency has decreased in size. ,

Removing a zirconia or ceramic post Retrieval of zirconia and ceramic posts can be very dif ficult if endodontic retreatment is necessary or the post fractures. Some ceramic materials can be removed by grinding away the remaining post material with a bur, but this is a tedious and dangerous procedure. The risk of removing surrounding tooth structure is significant. It is virtually impossible to grind away a zirconia post. The safest option is trying to loosen the post with ultrasonic vibration while troughing and dissecting along the cement line. Because ceramic and zirconia posts tend to be weaker than metal posts, a thicker post is often used, and in most cases dentin has to be sacrificed to remove them. Therefore, the clinician needs to carefully evaluate whether the remaining tooth structure is adequate for retreatment (Fig 17 -13) or if apical surgery or extraction is a better option.

Summary The following guidelines should be considered when at tempting to remove posts:

•Post removal should only be considered if there will be

adequate remaining tooth structure after its removal. If there is any doubt about the restorability, periapical surgery or extraction may be an alternative treatment option.

•Try to identify the type of post preoperatively using radiographs.

•Use magnification and isolate with rubber dam.

•Remove as much adjacent restorative material as possible and avoid reducing the post head too much in height or diameter to keep all options open for its removal. •Preserve coronal and radicular dentin.

•Use sufficient coolant when applying ultrasonic energy

to a metal post. •Switch to a post extraction device when ultrasonic vi-

bration is unsuccessful after about 10 minutes.

•FRC posts are reported to be easy to retrieve in vitro,

but their tooth-colored appearance makes them difficult to distinguish from dentin. Do not underestimate the difficulty of removal. •Wetting the surface of an FRC post is helpful to distinguish it from dentin and composite. •After post removal, a careful inspection of the root should be carried out to evaluate the integrity of the remaining root structure and assess the restorability of the tooth.

Recommended Reading Abbott PV. Incidence of root fractures and methods used for post removal. Int Endod J 2002;35:63-67. Davis S, Gluskin AH, Livingood PM, Chambers DW. Analysis of temperature rise and the use of coolants in the dissipation of ultrasonic heat buildup during post removal. J Endod 2010;36:1892-1896. Forde R, Baba NZ, Jekki B. Removal of posts. In: Baba NZ (ed). Contemporary Restoration of Endodontically Treated Teeth: Evidence- Based Diagnosis and Treatment Planning. Chica go: Quintessence, 2013:181-194. Frazer RQ, Kovarik RE, Chance KB, Mitchell RJ. Removal time of fiber posts versus titanium posts. Am J Dent 2008;21:175-178. Gluskin AH, Ruddle CJ, Zinman EJ. Thermal injury through intraradicular heat transfer using ultrasonic devices: Precautions and practical preventive strategies. J Am Dent Assoc 2005; 136:1286-1293. Peciuliene V, Rimkuviene J, Maneliene R, Pletkus R. Factors influencing the removal of posts. Stomatologija 2005;7:21-23. Ree M, Schwartz RS. The endo -restorative interface: Current concepts. Dent Clin North Am 2010;54:345-374.

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CHAPTER

Scott T. Weed, DDS

Removing Silver Points and Gutta-

Materials other than gutta -percha may be encountered in the retreatment process, and removal of these materials is a crucial step that can be quite challenging. Despite generally favorable research evidence and the fact that patients present regularly with decades- old silver point obturations that are successful (Fig 18 -1), silver points and carrier-based gutta -percha have been stigmatized over the years. The stigma surrounding these materials is that they are difficult to retreat when they fail. However, this is not necessarily true in most instances. This chapter discusses clinical strategies for their removal.

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Removing Silver Points and Gutta - Percha Carriers Fig 18-1 A mandibular left

Fig 18- 2 If the buildup is not completely removed over the carrier and gutta-percha (red arrow ), it can impede retrieval of the carrier.

first molar containing silver points. Note the periodontal ligament space regularity. Note also the coronal ends of the points folded along the chamber floor.

As clinicians, we should have a clearly defined purpose when prescribing retreatment and need to be careful in our assessment of radiographic surveys that " look suspicious." Several questions should be considered before initiating retreatment:

ly, the end of the silver points or carriers can usually be preserved as a handle to facilitate removal. The author removes restorative materials in the center of the chamber first; careful expansion laterally will uncover the ca nal orifices. If all the restorative material is not removed, it can act as a retentive feature for the silver point or gutta -percha carrier, making it more difficult to remove (Fig 18-2).

•Is the patient symptomatic, or has he or she ever been symptomatic ?

•Has the radiolucency changed in size?

•What are the hazards of retreatment? Is there a chance retreatment could make matters worse? Will retreatment "cure" the "problem "?

A Note on Irrigants and Solvents

tancy of the tooth?

The following techniques emphasize mechanical methods to remove silver points and gutta -percha carriers. These methods may be enhanced with the use of chemical solvents. The downside to solvents, however, is that they make the chamber " messy " and cause the gutta-percha to stick to the canal walls. Many clinicians attempt to remove the canal contents initially without solvents and only introduce them as necessary. Several irrigants and solvents are commonly used during retreatment. Organic solvents, like chloroform, eucalyptol, and eugenol, can help remove and dissolve the cement and gutta-percha that surround silver points, making them much easier to remove. They do the same for gutta-percha carriers. Sodium hypochlorite is an excellent adjunct because it dissolves necrotic debris that may be in the canal alongside the point or carrier. Sodium hypochlorite also acts as a lubricant and pulls organic debris into the solution. Ethylenediaminetetraacetic acid (EDTA) can soften dentin debris that may be packed in the canal. In many cases, all of these materials are needed to " outflank" a stubborn silver point or carrier. Water acts as a coolant and lubricant. It can be activated with sonic or ultrasonic energy and safely sprayed under

• •What is the restorative prognosis for the tooth? •Will retreatment increase or decrease the life expec•What

effect will failure have on future treatment options? •What are the risks associated with nontreatment or alternative treatments (like extraction)? •What is the total cost of treatment (not only in terms of money, but also in chair time, emotional energy, patient discomfort, etc)? •Will I be able to measure the outcome of the retreatment? •And perhaps the most important consideration: What does the patient want?

The decision to re-treat must be made with realistic expectations by all parties, understanding that treat ment is associated with very real hazards.

Chamber Cleanup The first step in any retreatment is removal of guttapercha, sealer, restorative materials, and any other impediments from the pulp chamber. If this is done careful-

pressure.

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Silver Points Fig 18- 3 Preoperative radiograph of a premolar obturated with a silver point. In this case, even though the tooth is asymptomatic, retreatment of the tooth was recommended because the root canal system had been exposed to the oral cavity for several weeks prior to the patient seeking care for the dislodged crown. The tooth can also be improved structurally by utilizing the canal space as an anchor for new restorative material. Note the “handle" (circle).

Fig 18- 4 If a handle is present, silver points can be held securely with well-machined dental instruments. Take care to loosen a silver point prior to applying strong traction forces to avoid breakage.

Silver Points

Crab and pull The simplest technique is usually the best one to try first when removing silver points. Remove the core buildup material, paying special attention to the very first signs of reaching the silver point(s). Be careful not to remove the exposed tips of the silver points along with the core material. Carefully remove the final remnants of the core with spoon excavators, endodontic explorers, ultrasonic tips, or very small, long rotary burs, such as Munce Discovery Burs (CJM Engineering) or EndoGuide burs (SS

Silver points were the most popular method of root ca nal obturation prior to the 1970s for several reasons:

•They are stiff and can be inserted into canals without buckling.

•They

can accommodate a conservative canal prepa ration because they do not require coronal flaring to facilitate condensation instruments

•They were often successful.

Fig 18- 5 After removal of the temporary material placed by the patient’s general dentist, the silver point was well visualized. Note the cement in the ovoid canal flanking the round silver point, which allows the introduction of hand instruments on two sides.

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Once the core is removed and the silver points are visible, grab them with cotton pliers or specialized forceps (Stieglitz, Roydent) and attempt to remove them with a gentle pulling force. Moderate to heavy force at this stage can result in the silver point breaking and can make removal of the remaining portion more difficult. However, quite often the point will release from the canal with a fortuitous light tug (Fig 18- 4).

The silver point technique generally involved the placement of a sealer or cement into the prepared canals followed by insertion of the silver point. Often we encounter " mixed" cases in which silver points were placed in the narrower and more curved canals while gutta-percha was placed in the larger and straighter ca nals. Additionally, some cases are encountered in which gutta-percha was placed into the coronal canal alongside the silver point. In most cases, several millimeters of the point were used as a "handle" for placement purposes, and rather than it being cut off flush with the canal orifice, it was folded over to the chamber floor and embedded in a zinc oxide-based material or amalgam. This handle is always a welcome windfall to silver point retrieval, and every ef fort should be extended to ensure that it is not removed during treatment (Fig 18-3).

Bypass technique If the silver point was not removed with a gentle tug, by pass it with small hand files as deeply as possible Sol . vents may be helpful in loosening the coronal cement. Most canals are not round, and there is generally at least one area, and often two, alongside the silver point that is exploitable with a hand file (Fig 18- 5). When removing any root canal filling material , patience is the name of the game. Minimize the loss of natural dentin. Silver points are soft, and a carefully bypassed silver point will show tracks where the file(s) passed (Fig 18- 6). Ledges and lateral perforations can occur if instruments are forced. Removal of a silver point is more predictable if it can

Silver point removal techniques Silver points are generally unmistakable on a periapical radiograph. They' are well demarcated and regular in profile with little taper, unlike a fractured instrument

that might have flutes or other machined features in its radiographic profile.

be completely bypassed with hand files. Bypassing may involve multiple rounds of small hand files and

generous

0 由　扫描全能王　扫描创建 0

[0 Removing Silver Points and Gutta -Percha Carriers Fig 18 -7 K - files bent with the EndoBender. The file on the left is bent at its last flute, while the file on the right is bent to its second- to-last flute.

Fig 18-6 (a and b ) After removal of this silver point, note the grooves where K -files were negotiated along the side of the soft silver point.

irrigation. However, it is not always necessary to bypass the entire silver point to remove it. You must "take what the tooth gives you." In many cases, the combination of instruments and solvents allows for the silver point to be removed on the second attempt at the grab and pull technique. Short -radius bends created near the tip of the file can be helpful in negotiating a path alongside a silver point (Fig 18 -7 ). These small bends can be accomplished with an EndoBender (Sybron) or a bird beak pliers.

Extraction devices Kits are available (Ruddle, Sybron; Gonon, Schwed; Outpost, SD Swiss) for removing various metal objects from a canal. A machined cylinder with left -handed female threads is threaded onto the exposed end of the silver point and acts as a handle. It is helpful to lubricate the threads with a drop of light machine oil or handpiece lubricant to facilitate engagement of the silver point. Once the silver point is engaged, attempt to gently tug it from the canal by hand. If unsuccessful, ultrasonic ac tivation of the handle (indirect, as explained below) may help loosen the point. These devices have another component that can be used to provide a lever action.

Hedstrom technique A Hedstrom file can sometimes be placed into the space created with small hand files and can engage the silver point with a slight clockwise rotation. However, it is im-

Other devices

portant to note that Hedstrom files, because of their ma chined profile and cross section, can break on rotation when wedged into a canal; the file should be rotated

only enough to slightly engage the flutes in the silver point. Once the silver point is engaged, clamp the Hedstrom file with a hemostat, use a cotton roll as a cushion, and gently fulcrum the hemostat. Often the silver point will come out with the Hedstrom file on the first try.

Generally, devices and techniques used to grab bro ken endodontic files can also be used for silver points. The key to remember is that the tensile strength of silver points is much lower than that of steel or nickeltitanium files. These techniques include the "tube and glue" and " lasso " techniques (see chapter 16) as well as the IRS (SD Swiss) and Basic Object Acquisition (CJM Engineering) devices.

Two - file technique

Indirect ultrasonic activation

For a stubborn silver point that has been bypassed along one side and still will not yield, bypassing at another location is the next step. This creates more space around the periphery of the silver point and also increases the frictional grip of the files. Place a second file on the opposite side of the silver point. Twist the file handles around each other (Fig 18-8) and lift out the silver point by hand, or clamp the files simultaneously with the hemostat and remove the silver point as previously

Direct contact from an ultrasonic tip will cause the soft silver points to " melt away " or, worse yet, to break off, making your job harder. Indirect ultrasonic energy, however, can be safely used to remove silver points. For example, ultrasonic energy can be applied to a stainless steel hand file that has bypassed the silver point or to a grasping instrument that engages the top of the file (Fig 18-9). Low power settings are advised, at least to start. It is far better to work your way up to the appropriate power setting than to start out too high and cause the silver point to fracture in the canal.

described.

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Silver Points

Fig 18- 8 Hedstrom files can be used with a hemostat to lever out a silver point or carrier.

Fig 18- 9 In most cases, an ultrasonic instrument should not be placed directly in contact with a soft silver point, as this will cause the soft silver material to "melt away, " resulting in loss of the handle. A safer strategy is to grasp the silver point with a forceps and touch it with the ultrasonic tip to apply indirect ultrasonic energy.

Fig 18- 10 (a to d ) A Hedstrom file and hemostat were used to remove a small silver point segment. (Courtesy of Dr Marga Ree, Purmerend, The Netherlands.)

Activating a file, spreader, or endodontic explorer in the canal alongside the silver point encourages the cement to break up as well as deeper solvent penetration. The canal should be " wet " when doing this, either with an organic solvent, sodium hypochlorite, EDTA, or water. An assistant should strategically place a vacuum tip in the area to capture spatter from the activation process.

Removing a fragment deep in the canal Some teeth contain a segment of a silver point deep in the canal, either because the coronal portion was removed to create a post space or the silver point broke when removal was attempted. Start by working small files around the silver point as previously described. If a lateral path can be created with small files, a Hedstrom file can sometimes be introduced to " snag" the silver point segment (Fig 18-10). Direct or indirect ultrasonic activation can also be used to retrieve deep fragments in a straight root. These methods might be considered when removing the frag-

deemed necessary; leaving it in situ would be unacceptable. The risks include damage to coronal restorations, pushing the fragment into the periapical tissues, and failure to remove the fragment. ment is

Surgical removal In the event that an entire silver point or deep fragment cannot

be removed nonsurgically, a surgical approach

may be used. In some cases, surgical treatment may be more conservative than nonsurgical techniques that could result in dentin loss from the coronal and cervical

parts of the tooth.

Sometimes during surgery a silver point can be re moved apically or pushed coronally and removed through the chamber. The silver point is most likely to be dislodged with direct ultrasonic activity. If it cannot be removed, the silver is quite soft and a retropreparation can be prepared easily with an ultrasonic tip. Root amputation is also sometimes an option.

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m

Removing Silver Points and Gutta - Percha Carriers

Fig 18-11 (a and b) Two examples of metal carriers. Note the irregular edges.

Fig 18-12 An IRS instrument was used to grab and retrieve a metal carrier.

Gutta-Percha Carriers

Hand file technique Once the gutta -percha has been removed coronally, attempt to keep going with hand files to completely bypass the metal carrier. Once the carrier is bypassed with smaller hand files, enlarge the path to a size 20. Usually at this point, or sometimes earlier, the metal carrier will loosen and can be removed. Hedstrom files can work with metal carriers, but they do not engage the metal carrier (stainless steel) as well as they do plastic carriers and, to a

Metal gutta-percha carrier removal techniques Carrier-based techniques were first described in 1978 and commercialized about 10 years later. The original technique used a metal endodontic file as a carrier covered with gutta-percha. These metal carriers were manufactured until the 1990s, when they were largely replaced with plastic carriers. This knowledge can help the clinician approximately date cases treated with metal carriers. Because the early iterations of metal carriers were in fact K - files, they appear radiographically like a file in the canal. The hallmark of the metal carrier that distinguishes it from plastic carriers or silver points is the presence of flutes (Fig 18-11). Because metal carriers are the same as K- files, some of the techniques for removing them are similar to those used to remove silver points or separat ed instruments. If any portion of the carrier protrudes from the canal orifice into the pulp chamber, take great care to preserve it as a handle. A careful counterclockwise twist will often aid in its removal.

lesser degree, silver points. If bypassing does not loosen the carrier, even with subsequent applications of solvent, try to bypass it at another location, ideally 180 degrees from the first bypass.

Hand file technique (with a twist ) Once the metal carrier has been bypassed in two places, place a K-file to length in each place (two files) and twist them around each other and the carrier. Remember that most metal carriers, like K- files, have right-handed threads, so twist the files counterclockwise (see Fig 18-8). The metal carrier will often unscrew and can be removed.

Heated technique

Exploit the coronal canal

A heat carrier (System B or Touch'n Heat, Sybron) can sometimes be used judiciously to soften gutta -percha in the canal with a metal carrier. Apply the heat directly to the gutta -percha if the width of the canal allows it. Once a portion of the metal carrier is exposed, apply heat directly to the carrier to soften the surrounding guttapercha. Work around the carrier with hand files immediately before the gutta-percha cools. The area should be completely dry before attempting heat application

Carriers were developed at the same time that coronal flaring of the canal was popular, so in most cases there was space around the coronal portion of the carrier. Therefore, the first focus is to remove as much gutta percha as possible from around the carrier. Organic solvents are helpful for this task. It is not recommended to introduce rotary files into canals with metal carriers because often you will end up with two pieces of metal in the canal.

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Gutta - Percha Carriers

Fig 18-13 After the heat plugger has completely Fig 18-14 (a and b) The Hedstrom/hemostat technique also works well with plastic carriers, cooled, it is removed parallel to the long axis of the (Courtesy of Dr Tim McManus, Windsor, Ontario.) coronal third of the canal. (Courtesy of Dr Fiona McMichen, Surrey, England.)

keep the tip as still as possible during the cool-down. Water spray can aid the process. Once it is cooled, se cure the tip with a hemostat or your fingers, and pull it out of the canal parallel to the long axis of the tooth (Fig 18-13). A fortuitous pull will remove the carrier along with the tip.

File removal techniques Devices and techniques used for separated instruments can be equally applied to metal carriers once most or all of the gutta-percha has been removed. In Fig 18-12, an IRS instrument was used to remove a metal carrier.

Plastic gutta-percha carrier removal techniques

Hedstrom technique If the cooled tip comes out cleanly with no carrier at tached, the process can be repeated at another location. Alternatively, a Hedstrom file (or two) can be immediately inserted into the softened gutta-percha and given a slight clockwise twist to set it. A cotton roll or fingertip can be used as a fulcrum on an adjacent tooth for a hemostat to remove the files (hopefully with the carriers attached) (Fig 18 -14). Solvents used in conjunction with small hand or rotary files can also aid this process.

The vast majority of carrier retreatments today involve plastic carriers. Although they are patent protected, carriers of ISO size 45 and above are made of polysulfone, which is not resistant to organic solvents like chloroform. Carriers smaller than ISO 45 consist of 4- acetoxybenzoic acid/6-acetoxy-2-naphthoic acid copolymer, a polyes ter that is resistant to solvents (insoluble). Clinically, all plastic carriers appear to be insoluble despite the stat ed properties of polysulfone. Most plastic carriers have a groove along the side to facilitate negotiation with a hand or rotary file. However, this is not the case with all plastic carriers. Some of the newer carriers are made of cross-linked gutta -percha. Manufacturers state that they are soluble in organic solvents, but clinical experience seems to indicate that if they are soluble, they are not as easily dissolved as typical gutta -percha.

Removal with rotaries At this point, if all attempts to remove the carrier have failed, it can sometimes be ground out or popped out of the canal with medium-sized rotary instruments. Unless the carrier fits very tightly in the canal, a rotary file can usually be introduced along the side of the carrier and gradually worked apically. Sometimes the carrier pops out with this method, but more commonly it ends up partially shredded and pressed against the opposite canal wall. It can sometimes be peeled away from the wall and removed with an endo explorer, or a Hedstrom file can be introduced between the carrier and the canal wall to snag it. The rotary method is more dangerous than the hand file/Hedstrom methods but works well in most cases. In fact, for some clinicians this is their go-to method for removing plastic carriers.

Heated plugger technique Carrier-based obturation is a true thermoplastic technique, and this can sometimes be used to our advantage to remove them. One method is to use a heat source such as System B or Touch'n Heat. With the heat source at a high setting, plunge the heated tip into the gutta percha along the side of the plastic carrier. Once it has penetrated 4 to 6 mm into the canal, let it cool. Try to

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KQ

Removing Silver Points and Gutta-Percha Carriers

Surgery

Summary

When all else fails, apical surgery may be the only re maining option other than extraction. Plastic carriers are easily resected and allow adequate ultrasonic

retropreparation.

Retreatment of teeth obturated with silver points and carrier-based gutta-percha can be challenging and is generally more prone to procedural accidents than gutta -percha obturation. This chapter reviewed several methods for removing these materials safely.

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CHAPTER

Ivan N. Vyuchnov, DDS, MSC

Retreatment of Teeth Containing " Russian Red "

The "Russian Red" technique utilizes a red chemical-cure resorcinol formaldehyde resin for obturating root canals, so once polymerized, it is hard to penetrate. It is usually, but not always, radiopaque and is easy to identify clinically because of the characteristic red color. However, it can be very challenging to remove if retreatment is indicated. When considering retreatment in general and retreatment of Russian Red in particular, several questions must be considered:

•Do root-filled asymptomatic teeth with periapical radiolucencies automatically require retreatment? •What if a small periapical radiolucency is unchanged from historical radiographs? •Is a poor-quality root fill reason enough for retreatment? •Will retreatment extend or shorten the life span of the tooth?

These questions are particularly relevant in challenging cases such as those typically seen with Russian Red. This chapter reviews nonsurgical and surgical methods for retreating teeth with Russian Red.

Historical Overview Although the material is referred to as Russian Red, it was neither invented nor popularized by Russian (Soviet) scientists. In early 1898, Gysi, who was Swiss, introduced the material, and Albrecht popularized it in 1912. It was never referred to as "Swiss Red," however. It was recommended for use after removal of the coronal pulp and was applied into the root canal orifice to cause fixation of the remain-

ing pulp tissue. The original technique took about five appointments to fully instrument and obturate the root canal system, but improvements in instruments and techniques eventually allowed it to be completed in a single appointment. A tooth that contains Russian Red has a characteristic pink discoloration. The technique became very popular among clinicians in Eastern Europe, who claimed that the procedure resulted in patients who were pain free. It was used with both vital and necrotic pulps.

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B3

Retreatment of Teeth Containing " Russian Red " Endodontic Paste

Fig 19- 1 (a to d) Typical Russian Red cases referred to the author 's endodontic practice. They feature minimal obturating matenal in the apical half of the root with blockages and ledges in the middle and apical thirds. Most of these teeth are asymptomatic

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small radiolucency. Some questions the following:

Clinical Categorization and Description

to

consider include

•Are historical radiographs available that show the relative size of the radiolucency in the past? •How difficult is retreatment likely to be? •Is a new restorative treatment planned? •Does the patient have other, more pressing dental needs?

Teeth with Russian Red obturation tend to have several common features. The canals tend to be opened quite large coronally, often with a Gates Glidden bur or Peeso reamer. They are often ledged in the midroot with minimal or no instrumentation apical to the ledge. The composite resin tends to be quite dense in the coronal third of the root but sparse or absent in the apical twothirds, something that can make retreatment easier (Fig 19-1). Many of the teeth originally treated with Russian Red have been asymptomatic for years despite what appears to be inadequate debridement and the presence

Symptomatic tooth with a periapical

radiolucency This type of case usually requires retreatment or extraction.

of a periapical radiolucency. There are several types of Russian Red cases that are referred to the author's endodontic practice in Moscow. Careful observation of these cases has helped the author in clinical decision-making and in predicting outcomes of treatment.

Armamentarium Retreatment of Russian Red is very difficult if the clinician is not trained to work under the surgical operating microscope using small, specially designed instruments that allow visualization deep in the canal. This includes microsuction and a microtipped air- water syringe as well as small ultrasonic instruments designed so that the handle does not obstruct vision into the canal. Assistantside oculars allow the assistant to simultaneously see what the endodontist sees inside the tooth and are a

Asymptomatic tooth with no radiographic findings If the tooth is asymptomatic with no radiographic findings, the canal preparation was probably adequate in terms of chemomechanical cleaning of the root canal system prior to obturation. There are few indications to retreat this type of tooth. Retreatment might make the radiograph look better, but the process can be very dif ficult and may actually reduce the functional life span of the tooth.

must to operate

efficiently.

The predominant instruments used to remove Russian Red are a diamond-coated ultrasonic tip (Fig 19-2), small hand files (Fig 19- 3), and a device to activate them with ultrasonic energy (Fig 19- 4). The ultrasonic tip removes the restorative material from the pulp chamber and the hard paste from the orifice and coronal third of the canal. This is done carefully under the microscope and creates a staging platform for the introduction of endodontic files.

Asymptomatic tooth with a widened periodontal ligament space or small

radiolucency

Retreatment is also not necessary for many asymptomatic teeth with a widened periodontal ligament space or

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Technique

Fig 19- 2 (a and b ) Diamond-coated ultrasonic tips are used for initial removal of the hard paste in the chamber and at the orifice level. This allows for "scout ing" with small, stiff hand files.

Fig 19- 3 C-files have a stiffer core than conventional K-files and are used in the initial stages of re-treating teeth with Russian Red.

Fig 19-4 (a to d) IrriSafe files (Satelec) help the clinician deliberately remove paste from the root canal without removing an excessive amount of viable dentin tooth structure, thereby protecting the tooth from possible fracture in the future.

Small, stiff hand files such as the C-file (VDW) or C+ file (Dentsply) are used to penetrate the hard resin or bypass it (see Fig 19-3). These files are rhomboid in cross section and have fewer flutes than a regular file. This design allows less binding of the canal walls and increased stiffness compared with K-files. Rotary files can be useful in the early stages but often become blocked in the middle third. They are prone to transportation of the canal or perforation if apical pressure is applied. They also tend to overenlarge the coronal part of the canal, leaving space in which the file will bend, thereby reducing the stiffness and making it more difficult to maintain a centered position. The use of solvents with Russian Red is controversial. In the author's experience, it is doubtful that they make a difference. Irrigants such as ethylenediaminetetraacetic acid (EDTA) and sodium hypochlorite can be helpful in cleaning the dentin surface and providing visualization of the middle and apical thirds of the root canal under high ma gnification. Once the Russian Red is removed, locating and negotiating the canals follows the same process as described in chapter 10. Devices such as Endosonore (QED), Endo Chuck (Dent America), or the IrriSafe file (Satelec) were developed to deliver ultrasonic energy to irrigating solutions, but they can also be helpful in re-treating teeth with Russian Red. These instruments are very helpful for every stage of root canal instrumentation, including bypassing the paste, removing it once it has been bypassed, as well as cleaning grooves and isthmuses. The file can be bent into multiple angles so you can work under the microscope without blocking visualization of the site (see Fig 19- 4c). The chairside assistant can help by continually blowing out the dust accumulated during ultrasonic activation.

EndoGuide burs (SS White) are helpful in making conservative access preparations, locating the canal orifice, and troughing grooves. The EndoBender (Sybron) allows small bends to be placed at the tip of a file, which is helpful in negotiating the canals, bypassing ledges, and finding the location of the canal's natural portal of exit.

Technique Each tooth and every canal is unique and different, so there is no such thing as a standard protocol. However, there are certain techniques that have proved to be suc cessful in many cases. The instrumentation protocol for treating teeth with Russian Red should be divided into three parts: 1. The coronal third 2. The middle third 3. The apical third

The coronal third Once the restorative material has been removed from the pulp chamber and the orifices are located, small hand files are introduced. If you are lucky, it may be possible to " watch-wind" the file to patency. In most cases, however, it will be blocked at the orifice or after a short distance into the canal. When the initial scouting files are blocked, it is necessary to enter the canal with the diamond-coated ultrasonic tips. Like most pastes, Russian Red tends to be most dense in the coronal third of the canal, and if the paste can be removed from that area, negotiation of

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19 Retreatment of Teeth Containing " Russian Red " Endodontic Paste

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the rest of the canal tends to be easier It is important to mention that diamond-coated ultrasonic tips should not go deeper than the middle third of the canal, and the clinician must be careful to always stay "on line " with the original canal. Use of the dentin map to uncover root ca nal anatomy is described in chapter 11 Cutting off the tip of a file to make it end-cutting is generally not recommended because it can lead to canal perforation or transportation. Experienced users can apply this technique in the coronal part of the root canal where the obturation material is still visible.

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The middle third Once a file has reached the middle third of the canal, the sequence of files starting from ISO size 15 to ISO size 6 (15, 12, 10, 8, 6) is used with light but steady apical pressure in a balanced-force motion. If the paste is still dense enough to resist apical progress, search for a path alongside the paste. Isthmus areas are most likely to produce a path to bypass. C+ files and C- files, used in tandem, can be very effec tive. Rigid C + files can sometimes penetrate the obturation material, while C-files are less rigid, more flexible, and tend to follow the canal path more readily. You must always be careful with C+ files, because they are more likely to create a false path in the dentin. Use the C+ files only to create a path for the less rigid C-files. When the file is inserted with apical pressure and requires some force to remove it, this usually means that you are on the right track. Once you are past the composite resin and into the canal, instrumentation of the apical portion of the canal tends to be straightforward.

The apical third When instrumenting the apical third, it is important to pay close attention to the presence of obturation mate rial debris in the flutes of the files. This helps to decrease the likelihood of canal transportation or perforation. It is also helpful to note the curvature of the file as it is removed, which indicates whether the true canal path is being followed. In most cases, there is not very much

Clinical Cases Case 19- 1 An asymptomatic, healthy 38-year-old woman was referred for endodontic retreatment prior to new crown fabrication on the maxillary left first molar. A periapical radiograph revealed three canals partially obturated with Russian Red and a radiolucency at the apex of the mesiobuccal root (Fig 19-5a). Upon access, remnants of necrotic pulp tissue were noted in the chamber. Note the pinkish-red color of the chamber (Figs 19-5b to 19-5f). A previously untreated second mesiobuccal canal

instrumented to full length with hand instruments. Russian Red blocked the mesiobuccal and distobuccal canals in the coronal third. The author was able to remove the composite resin from the coronal third with the diamond-coated ultrasonic tip and use precurved size 15 and 10 C-files to negotiate the original canals and achieve patency. Upon removal of the files from the canal, was located and

the flutes were checked for obturation material debris, and their curvature was noted to ensure maintenance of the true canal path. The palatal canal was managed in much the same way but was instrumented with an IrriSafe ISO 15 file just short of the radiographic apex. Once the firmly set ma terial was removed, hand files from 15C to 8C were introduced in a watch - winding motion in order to achieve patency.

The patient experienced a flare-up after the first appointment, which was managed pharmacologically. The calcium hydroxide was replaced twice, final shaping was performed, the canals were obturated, and a definitive amalgam restoration was placed. At the 6-month recall, the patient was asymptomatic, and there was clear evidence of bone healing (Fig 19-5 g).

Case 19- 2 A 64-year-old man was referred for retreatment of a structurally compromised, symptomatic mandibular right first molar (Fig 19 -6a). The provisional restoration was removed, and the orifices were exposed. An isthmus between the mesiolingual and mesiobuccal canals was troughed with an EndoGuide bur, which uncovered two untreated canals that were occluded with dentin dust. False canals had been previously created to the buccal and lingual of the true canals (Figs 19-6b to 19-6e). Once the canals were located and fully instrumented, calcium hydroxide was placed as an interim medication and the tooth was provisionalized. At the next appointment, the patient was asymptomatic, the canals were obturated, and the tooth was definitively restored (Figs 19-6f to 19-6h). Figures 19- 6i and 19 -6j show the immediate postoperative and 1 - year recall radiographs, respectively.

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paste in the apical third

The usual sequence is ISO 15, 12, 10, 8, 6 in a watch- winding motion with steady apical pressure. In longer and smaller canals, smaller- diameter files (eg, ISO 8 and 6) can be used because they are less likely to ledge or block the canal. If a ledge is present, visualize the natural curvature of the canal and the likely position of the ledge, then use small hand files with apical bends to bypass it. Irrigation with EDTA and sodium hypochlorite at the end of each file sequence is important. It helps to remove debris and lubricates the canal for advancement of the files.

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Clinical Cases

Fig 19-5 (a) Periapical radiograph showing three canals partially obturated with Russian Red and a radiolucency at the apex of the mesiobuccal root, (b to f ) The pinkish-red color of the chamber is typical of a tooth obturated with Russian Red. ( g ) Six-month recall radiograph showing partial bone regeneration.

Case 19-2

Fig 19-6 (a ) A structurally compromised, symptomatic mandibular right first molar, (b to e ) After the isthmus was troughed, the natural canals were located ( green arrows ). The yellow arrows indicate the presence of false path canals.

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|Q Retreatment of Teeth Containing " Russian Red " Endodontic Paste

Case 19-2 ( cont )

Fig 19-6 (cont ) (( to h) A series of radiographs and clinical photographs showing the progression of treatment including core placement, ( i ) Immediate postoperative radiograph, ( j ) One- year recall radiograph.

Case 19- 3

paste was still dense and resistant in the middle third. The

author instrumented the next few millimeters carefully with ISO 10, 8, and 6 C-files only. For the following few millimeters, only ISO 8 and 6 files were used. The size 8 files created a channel only slightly bigger than the size 6 files, so the walls of the channel supported the size 6 files, maintained their stiffness, and kept them from buck ling when apical pressure was applied. With patience and many hand files, the paste was penetrated and the canals were located. Once the canals were patent, they were cleaned and shaped, calcium hydroxide was placed , and they were obturated at the next appointment A . definitive alloy core was placed after removal of the composite interim core (Figs 19-7g to 19-7j)

This patient was referred for retreatment of a structurally compromised maxillary left second molar (Fig 19-7 a). This case is an example of how multiple appointments are sometimes necessary to achieve patency. The Russian Red obturation ended in the middle third of the root canal systems. A pre -endodontic buildup (see chapter 22) was placed with composite resin and a copper band to protect the tooth and help with isolation during the endodontic pro cedures (Figs 19-7b to 19-7f). Access was made through the buildup, the canals were located, and the Russian Red was removed in the coronal third as previously described. C-files were then introduced from ISO size 15 to 6. The

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Clinical Cases

Fig 19-7 (a ) The maxillary left second molar shows no signs of periapical disease. This often indicates that instrumentation to patency will be a challenge, (b and c) A pre-endodontic buildup was performed using a copper band and composite resin, (d to f ) The copper band was left in place throughout the endodontic procedure to protect the tooth from possible fracture, ( g to j ) After the canals were obturated, the pre-endodontic buildup was removed, and the definitive alloy buildup was placed.

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19

Retreatment of Teeth Containing " Russian Red " Endodontic Paste

Case 19-4

Fig 19- 8 (a ) A 52-year-old man with asymptomatic chronic apical infection was referred for retreatment of the maxillary left first molar, (b to e ) The author was able to re - treat the distobuccal and palatal canals but was unable to negotiate the mesiobuccal canals. Root -end surgery was necessary on the mesiobuccal root, (f and g ) Immediate postoperative photograph and radiograph, (h) Six -month recall radiograph showing the definitive restoration in place and bone regeneration that is nearly complete.

Case 19- 4

Conclusion

Sometimes it is not possible to negotiate all the canals due to difficult root canal anatomy, blockages, or calcification, and a surgical approach may be indicated. This 52-year- old man with asymptomatic chronic apical infec tion was referred for retreatment of the maxillary left first molar (Fig 19 - 8 a). The author re - treated the distobuccal and palatal canals but was unable to locate and negotiate the mesiobuccal canals. The mesiobuccal "channels " were obturated far short of the apex, and the tooth was restored (Figs 19- 8b to 19 - 8e). The root end was partially resected (Fig 19 -8f), the canals were located apically, and a retrofilling was placed (Fig 19-8 g). The 6-month recall radiograph shows that bone regeneration is nearly complete (Fig 19 -8h).

While there is no ideal technique for every case, it is hoped that some of the techniques presented in this chapter will help clinicians to maintain the natural dentition of their patients despite the challenge of re-treating teeth with Russian Red paste obturation.

Recommended Reading Schwandt NW, Gound TG. Resorcinol -formaldehyde resin " Russian Red" endodontic therapy. J Endod 2003;29: 435-437. Vranas RN, Hartwell G, Moon PC. The effect of endodontic solutions on resorcinol-formalin paste. J Endod 2003;29: 69-72.

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CHAPTER

Robert Corr, DDS, MS

A root perforation is an artificial communication from inside the tooth into the periodontal tissues resulting from a pathologic process or procedural accident. The focus of this chapter is limited to the management of subcrestal mechanical perforations resulting from a procedural accide nt during endodontic treatment. Perforations can occur even under the cautious eye of skilled clinicians. Iatrogenic perforations can happen during access preparation, instrumentation of canals, or endore storative procedures such as post space preparation, and they generally result in compromise to the tooth's prognosis. Prevention is the first line of defense. Prudent use of diagnostic tools and visual aids as well as careful techniques should lead to very rare occurrences of this procedural mishap . When perforations do occur, it is important to make an honest assessment of the progno sis and consider viable replace ment options for the most favorable patient-centered outcome. The decision to attempt repair of a perforated tooth should factor in the strategic value of the tooth, the overall restorative and periodontal prognosis, the functional demands on the tooth, as well as the potential consequences to the comprehensive health and function of the patient in the event that treatment fails. The consequences of perforation include damage to the periodo ntal tissues adjacent to the site of injury, with possible resorption of adjacent hard tissues and the spread of inflammation along the periodontal ligament space. This can result in a persistent periodo ntal pocket due to apical migration of epithelium.

The potential for a favorable periodontal tissue response after perforation is influenced by a vari ety of factors. It is generally believed that healing is less likely if there is a communication between the perforation defect and the oral cavity or a preoperative radiolucency at the site. These variables are more likely to develop and cause more advanced periodontal breakdown if repair is delaye d. Therefore, immediate repair is recommended. Early articles indicated that healing was advers ely affected when perforations were larger in size and that the location of the defect influen ced the outcome; however, more recent reports since the introduction of bioactive materials suggest that the healing response may be independent of the size of the defect.1 3 "

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El

Repair of Iatrogenic Perforations

Perforations close to the alveolar crest may present a greater challenge, because they are more likely to result

Perforation Repair Technique

resolve regardless of treatment efforts. Furthermore, crestal perforations weaken the pericervical dentin, which compromises the structural integrity of the tooth and may render it more vulnerable to structural failure.

Figure 20 -1a shows a radiograph of a patient who was referred to an endodontist when attempts to retrieve a silver point from the maxillary right lateral incisor result ed in a facial perforation. The treatment approach used represents the standard technique for many perforation

in a periodontal defect that communicates with the oral cavity. Once established, this communication may not

repairs.

Materials and Procedural Sequencing A variety of materials have been used to repair perforations. Prior to the introduction of mineral trioxide a 99 re9ate (MTA), materials such as composite, glass ionomer, and amalgam were used with generally disappointing results, and these materials are no longer recommended. The introduction of MTA has resulted in more encouraging outcomes45 and has established bioactive materials as the materials of choice. MTA has been thoroughly investigated in vitro and in vivo, and the favorable biologic response is well documented.6 Newer bioactive materials have been introduced and may be comparable to MTA for perforation repair, but the author still prefers MTA. Because the prognosis for perforation repair is time-dependent, it is wise to repair the defect as soon as practical after the injury is discovered. There are three primary strategies for sequencing an orthograde perforation repair with the endodontic treatment:

1. Restore the defect immediately, prior to completing the endodontic procedures. Immediate repair offers the advantage of protecting the exposed periodontal tissues from additional injury throughout the remaining course of treatment. When this option is considered, it is sometimes wise to temporari-

ly block the root canals with a retrievable material avoid creating canal obstructions with the repair materials. 2. Complete the instrumentation and disinfection procedures, and then perform the obturation as well as the repair of the defect concomitantly using the same material. 3. Obturate the canal apical to the defect with standard methods, and then repair the perforation (filling the rest of the canal with the obturating material) as a separate step. This option requires special care to avoid extruding the apical obturation materials into the perforation defect. to

1 . Decontaminate the site and achieve

hemostasis A sterile cotton pellet lightly saturated with 1.5% sodium hypochlorite was placed over the exposed tissues for 3 to 5 minutes for disinfection and hemostasis (Fig 20-1b). Heat cautery or hemostatic medicaments such as Viscostat (Ultradent) may be used when hemostasis cannot be achieved with sodium hypochlorite alone. Heavy bleeding may be an indication of significant

inflammation.

2. Block out the other canals A sterile cotton pellet was placed in the canal orifice to prevent obstruction of the canals with repair materials. A Hedstrom file was later used to engage and withdraw the cotton when the repair was complete. In some cases, no block-out is necessary

.

3. Place an external barrier if needed When possible, MTA should be placed directly without a barrier, because some investigations have demonstrated the most favorable periodontal healing when the repair material contacts the tissues directly. In most cases, the adjacent periradicular tissues provide sufficient support for gentle placement of the repair material. Small extrusions of MTA are generally not problematic.7 However, if the defect is large or the adjacent tissues lack sufficient support, whether due to direct injury or pathologic process, significant extrusion through the defect may occur. In such cases, a bioresorbable barrier can be placed through the defect to provide resistance to extrusion of the repair material. Collagen barriers absorb moisture and provide a source of moisture for the MTA to set appropriately. Alternatively, some clinicians use plaster products such as calcium sulfate that expose the MTA to less moisture but seem to work nonetheless. In this case, a collagen barrier was placed (Fig 20-1c).

4. Place the material Prepare the MTA according to the manufacturer's rec ommendations. The water-powder ratio can be varied slightly to alter the consistency of the material to achieve your preferred handling characteristics. A thicker mix of

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Perforation Repair Technique

Fig 20- 1 a A preoperative radiograph shows a lateral root perforation affecting the maxil lary right lateral incisor.

-

Fig 20- 1 b Clinical view of the lateral incisor after disinfection and hemostasis,

Fig 20- 1 d The perforation channel is filled with MTA.

MTA generally offers more user-friendly handling prop erties for larger defects, whereas a thinner consistency may allow for better flow into smaller or narrower defects. Once the desired consistency is achieved, a small carrier such as a Dovgan carrier ( Quality Aspirators) or MAP System (Dentsply Tulsa Dental) may be used to

deliver a small aliquot of material

to

Fig 20- 1 c A CollaCote barrier (Zimmer Dental) was placed to help contain the repair ma-

terial.

Fig 20-1 e A flowable composite resin was placed over the MTA and light cured to protect the unset MTA during subsequent immediate restorative procedures.

furcal perforations, then a small bulk of material should be placed over the surrounding dentin as well. With a dense placement, a brief gentle rinse with water can be used to help flush excess material from around the re pair. Figure 20-1d shows the perforation defect repaired with MTA.

the perforation

site. The MTA is gently guided into the defect using an endodontic explorer for very small defects or an appropriately sized endodontic condenser for larger defects.

5. Restore over the repair material Current repair materials are not recommended for use therefore, an appropriate restorative material should be placed over the repair. MTA requires moisture to set appropriately, and some clinicians piace a moist cotton pellet over the MTA for 24 hours, ensur ing that the MTA has set before placing the definitive restoration. In many cases, the adjacent periradicular tissues may provide a sufficient source of moisture, allowing for immediate restoration. In order to avoid disturbing the MTA during the subsequent restorative procedures, a small amount of glass ionomer or flowable resin can be used to cover and protect the MTA when immediate restoration is considered (Fig 20-1e).

Indirect ultrasonic condensation of the material can be achieved by activating the handle of the condenser with the touch of an ultrasonic instrument during placement. This helps to reduce voids and ensure denser filling and better adaptation. The MTA can be gently tamped with cotton or a blunt end of a paper point. Excessive compaction of the material is unnecessary and may result in unwanted extrusion of the MTA through the defect. Sufficient material should be present to ensure stability during setting. When the perforation forms a channel, such as a post space perforation, filling the defect alone is generally sufficient to support the MTA. However, when the defect has no lateral walls, as is common with

as core materials;

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Repair of Iatrogenic Perforations Fig 20- 1 (cont ) (f ) A postoperative radiograph demonstrates favor-

able placement of the repair material, (g ) The 12-year recall radiograph suggests a normal periodontal ligament and lamina dura adjacent to the perforation site. (Case courtesy of Dr Scott Bentkover, Chicago, Illinois.)

6. Assess the outcomes

feet with gray MTA prior to managing the canal systems. Gray MTA was placed (Fig 20-2d), and given the available moisture from the adjacent tissues, the MTA was capped immediately with flowable resin (Fig 20-2e) to allow the endodontic procedures to continue. The previously untreated mesiolingual canal was located, and the remaining canals were retreated as well. The tooth was restored immediately upon completion with a fiber post and resin core. Review of the immediate postoperative radiograph demonstrates a favorable procedural result (Fig 20-2f). At the 2.5 -year recall, the periodontal probing depths normalized, and the radiograph demonstrates evidence of healing (Fig 20-2g).

The repair should appear dense, and ideally it should be flush with the root boundary on immediate radiographic examination. Short-term follow-up at 1 year should demonstrate resolution of adjacent radiolucencies, normal periodontal health, and satisfactory function for the patient. Long-term follow-ups are encouraged to ensure a patient - centered outcome of comfort and function as well as continued absence of disease (Figs 20-1f and 20-1g)

Clinical Cases

Case 20- 2: Repair of a lateral root perforation (coronal)

Case 20-1: Repair of a furcal

This case demonstrates a favorable response to repair of a large, coronally positioned lateral root perforation and associated radiolucency. Initial root canal treatment prior to referral to an endodontist resulted in a file sep aration and lateral root perforation during retrieval at tempts (Fig 20-3a). During the first visit to the endodontic office, the instrument fragment was bypassed, and the perforation was repaired with MTA (Fig 20- 3b). The fragment was retrieved during the second visit, and the canals were medicated with calcium hydroxide for an additional 2 months, during which time the patient became symptom free. The canals were subsequently ob turated (Fig 20-3c), and the tooth was restored. Radio graphic examination at the time of completion reveals a favorable procedural outcome (Fig 20-3d). At the 1-year recall, deep furcation probings were reduced to normal depths, and radiographic findings suggest that the periradicular tissues are healing (Fig 20-3e).

perforation The patient was referred to an endodontist with a large furcation perforation that had been repaired 6 years earlier with amalgam and was associated with a furcal radiolucency, a communicating periodontal pocket with purulent exudate, and a sinus tract (Figs 20-2a and 20-2b). Despite the poor prognosis for perforation repair, the patient requested that treatment be attempted. This example demonstrates the possibility for successful healing despite poor preoperative conditions. The referring doctor created the perforation originally while exploring for the mesiolingual canal and repaired it with amalgam. A sinus tract appeared 6 years later, at which point the patient was referred for retreatment. The tooth was accessed, and the previous restorative materials were removed to expose the perforation defect (Fig 20-2c). In this case, the clinician elected to repair the de-

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Clinical Cases

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Fig 20-2 (aj The preoperative radiograph shows the previous furcal repair and the presence of a furcal radiolucency. (b) The clinical view upon disassembly shows the furcal perforation repaired with amalgam, (c) The broad perforation defect was decontaminated, and hemostasis was obtained, (d) The untreated mesiolingual canal was prepared, and MTA was used to repair the perforation, (e) The completed obturation and perforation repair. A layer of flowable resin was placed over the MTA to protect the repair during subsequent restorative procedures, (f ) The immediate postoperative radiograph shows the completed endodontic and restorative treatment, (g ) At the 2.5-year recall, the tooth was asymptomatic, there were no deep probings, and the radiograph suggests healing of furcal tissues. (Courtesy of Dr Mary Chien, Hacienda Heights, California.)

Case 20-2

Fig 20- 3 (a ) The preoperative radiograph shows the presence of a separated instrument fragment in the mesiolingual canal and a furcal perforation, ( b ) At the first appointment, the instrument segment was bypassed, the perforation defect was repaired with MTA, and the tooth was provisionalized. (c ) Clinical view after the MTA repair and obturation were complete, (d ) Immediate postoperative radiograph, (e ) The radiograph at 1 year suggests healing of the periapical and periradicular structures. (Courtesy of Dr Marga Ree, Purmerend, The Netherlands.)

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Fig 20- 4 (a ) The preoperative radiograph shows the separated instrument segment and perforation, (b ) The postoperative radiograph shows the completed perforation repair with MTA and obturation of the canal systems, (c) At the 6-month recall, the patient was asymptomatic, and the tooth was functioning normally.

Fig 20-5 (a) The preoperative radiograph demonstrates periodontal breakdown adjacent to a post perforation, (b ) The postoperative radiograph shows the MTA repair and definitive restoration, (c ) At the 1.5 -year recall, the patient was asymptomatic and the tooth was functioning normally. The radiograph demonstrates resolution of the lateral root radiolucency. (Courtesy of Dr Peter Mellin, Portland, Maine.)

Case 20- 3: Repair of a lateral root

Case 20- 4: Repair of a post preparation

perforation (apical third)

perforation

This case demonstrates the repair of a lateral root perforation at a midroot point of curvature in a Weine Type II (2:1) canal configuration. During initial treatment, a Hedstrom file separated at the point of confluence of the two mesial canals (Fig 20- 4a). A lateral root perforation occurred during attempts to retrieve the instrument with ultrasonic instruments and was discovered with the aid of an apex locator as well as bleeding spots on the lateral aspect of paper points. The remaining portion of the separated instrument was bypassed, and the canals and perforation site were medicated with calcium hydroxide. After shaping and disinfection procedures were completed, the apical portion of the canal was obturated using a high-temperature thermoplasticized injectable gutta percha technique (see chapter 14). Residual sealer was removed with alcohol and ultrasonic activation. The perforation channel was subsequently filled with gray MTA (Fig 20- 4b), which was delivered to the site in small aliquots using the MAP System and condensed with the aid of indirect ultrasonics on a premeasured endodontic condenser. A moist cotton sponge was placed over the MTA, and the tooth was provisionalized. At 4 weeks, all signs and symptoms had resolved, obturation was completed, and the tooth was restored. The 6-month follow-up radiograph shows a favorable short -term outcome (Fig 20-4c).

This case demonstrates a post that was placed in poor alignment to the long axis of the root, which resulted in perforation of the distal wall. The perforation was associated with a periradicular radiolucency and sinus tract at the time of referral to an endodontist (Fig 20- 5 a). The post was retrieved, the site was repaired immediately with white MTA without an external barrier, and the access was immediately restored with amalgam (Fig 20-5b). At the 1.5 -year recall, the patient was asymptomatic, the sinus tract had resolved, and the radiograph suggests resolution of the periradicular radiolucency and reconstitution of a periodontal ligament and lamina dura (Fig 20- 5c).

Summary Perforations are a frustrating procedural complication that may adversely affect the prognosis of the injured tooth. A growing body of literature demonstrates favorable healing outcomes using contemporary bioactive materials, although long-term reports (> 10 years) are fairly rare. With appropriate case selection and careful technique, repair may be a viable treatment option for perforated teeth.

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References

References 1. Krupp C, Bargholz C, Brusehaber M, Hulsmann M. Treatment outcome after repair of root perforations with mineral triox ide aggregate: A retrospective evaluation of 90 teeth. J Endod 2014;39:1364-1368. 2. Mente J, Hage N, Pfefferle T, et al. Treatment outcome of

-

mineral trioxide aggregate: Repair of root perforations. J En dod 2010;36:208-213. 3. Pontius V, Pontius O, Braun A, Frankenberger R, Roggendorf M. Retrospective evaluation of perforation repairs in 6 pri vate practices. J Endod 2013;39:1346-1358.

4. JOE Editorial Board. Procedural accidents: An online study guide. J Endod 2008;34(5 suppl):e65-e70. 5. Main C, Mirzayan N, Shabahang S, Torabinejad M. Repair of root perforations using mineral trioxide aggregate: A longterm study. J Endod 2004;30:80-83. 6. Parirokh M, Torabinejad M. Mineral trioxide aggregate: A comprehensive literature review—Part III: Clinical applications, drawbacks, and mechanism of action. J Endod 2010;36: 400-413. 7. Chang, S, Oh T, Lee W, Cheung, G, Kim H. Long- term observation of the mineral trioxide aggregate extrusion into the periapical lesion: A case series. Int J Oral Sci 2013;5:54-57.

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PART V

Restorative Considerations

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CHAPTER

Venkat Canakapalli, MDS

Evaluating Restorability

Practicing clinicians frequently face the decision of whether to perform endodontic treatment or extract. The decision to retain a tooth is made on the basis of risk versus reward and must consider multiple risk factors, including endodontic and periodontal criteria, the structural integrity of the tooth, caries risk, suitability as an implant site, as well as the perceived strategic value of the tooth

within the dentition. The skill level and experience of the clinician(s) performing the treatments are important factors in the decision-making process. Single risk factors are often easy to manage, but multiple risk factors may jeopardize the survival of a compromised tooth. The clinician also has to consider the consequences of tooth loss in the future and how failure will impact future restorative options. With the emergence of implants into the mainstream of dentistry, more emphasis has been placed on long-term outcomes. Retaining endodontically treated teeth as long as possible is no longer a given in the implant era. Instead, more emphasis is placed on evaluating the long-term prognosis and restorability of teeth prior to endodontic treatment. Patients are not well served if the endodontic treatment is successful but the tooth fails. Consequently, some teeth that might have received endodontic treatment in the past are now extracted if they are marginally restorable or if extraction makes more sense in the overall treatment plan. This chapter provides clinicians with a framework for the decision-making process of whether to treat or extract (Fig 21-1) and describes a method to evaluate restorability of a tooth prior to end-

odontic treatment.

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Fig 21-1 The decision-making tool used to evaluate the restorability of a tooth.

Fig 21- 2 Tooth restorability index (TRl). The tooth is divided into six areas for assessment of restorability.

Factors to Consider

What is the quality of the remaining coronal tooth structure?

Is the occlusion favorable?

Suprabony tooth structure is an important factor in de termining the restorative prognosis for a tooth. What constitutes adequate coronal tooth structure is not known, but there is general agreement that more is better, particularly in the cervical area of the tooth. Poste rior teeth that require endodontic treatment often have interproximal restorations, but if the buccal and lingual surfaces of the tooth are intact with at least 1 mm of height and thickness, it is considered adequate for a ferrule. The tooth restorability index (TRl) was devised to de termine the quality of coronal tooth structure and its contribution to crown retention and resistance. The TRl provides an overall numerical value. A molar, for example, is divided into six equal sections encompassing two proximal, two buccal, and two lingual areas (Fig 21-2). For each sextant, the coronal dentin's contribution to retention and resistance (ie, above the finishing line of the preparation) is reviewed, and the following scores are assigned. If in doubt, the lower score is assigned A scoring system of 0-3 is allocated to each section:

Occlusion is one factor that affects all areas of dentistry. Occlusal trauma is associated with tooth fracture and changes in the periodontium, among a myriad of other

negative effects. Mutually protected occlusion is considered the ideal occlusion by most clinicians. The anterior teeth "protect " the posterior teeth from lateral excursive forces, and the posterior teeth "protect" the anterior teeth from excessive vertical forces. In the posterior dentition, occlusal trauma is often related to noncentric contacts or "interferences." In the anterior teeth, it often occurs in the absence of posterior support. Occlusal trauma is exacerbated by bruxism or clenching and can destroy even the finest dentistry. In considering tooth retention, the occlusion should be carefully evaluated in every instance and modified if necessary.

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Factors to Consider Fig 21-3 This 64-year-old patient present ed with new decay in several teeth. She had a minimal history of decay until the past year, when she started on several new medications. The restorative dentist and periodontist asked these questions: ( ? ) If we restore her teeth, will she be back in 5 to 10 years with extensive decay? (2 ) Would she be better able to tolerate extractions and implant surgery now or in 5 to 10 years? (3) Would she have better implant sites now or in 5 to 10 years? (Courtesy of Dr Richard Schwartz, San Antonio, Texas.)

•0—None. Throughout two-thirds or more of the sex-

What is the patient's caries risk?

under consideration, there is no axial wall of dentin (ie, a box or missing cusp), or any dentin present above the finishing line is so lacking in height or thickness that it is unable to contribute to retention and resistance of a core or crown. This score is appropriate when a margin is visible just apical to the limit of a missing wall but there is only a small bevel or chamfer. •1 —Inadequate. Coronal dentin is present in the sextant, but it is insufficient in terms of thickness, height, or distribution (eg, an undermined cusp) to make any predictable contribution to retention and resistance. •2—Questionable. More dentin is present than with a score of 1, but not enough is present to make a predictable contribution to retention and resistance. This score should only be assigned when the operator finds it impossible to determine whether a score of 1 or 3 is more appropriate. Do not use it as a default category. •3—Adequate. There is sufficient coronal dentin in terms of height, thickness, and distribution for the operator to feel confident that this sextant will contribute fully to retention and resistance of the core and defintant

Patients with high caries risk include those with poor oral hygiene and dietary habits as well as older patients who develop dry mouth naturally or due to their medications. These patients are poor candidates for tooth retention, particularly if the teeth are compromised. Some patients can be "turned around" with oral hygiene instruction, but most efforts are unsuccessful. Caries is not an issue with implants. In older patients with high caries risk, the clinician must consider a multiyear treatment plan that includes loss of additional teeth as well as the fact that the patient's health and tolerance for surgery are likely to decline as he or she gets older (Fig 21-3).

Has there been recent restorative treatment ? Irreversible pulpitis after recent restorative treatment is not uncommon, and these teeth are usually at low risk for negative outcomes from root canal treatment (Fig 21- 4) On the other hand, a tooth with old restorative treatment that was stable for many years and now requires endodontic treatment is more likely to have a poor prognosis due to fractures, caries, or other issues. Old restorative treatment with pins frequently leads to cracks (Figs 21- 5).

.

itive restoration.

Thus, a maximum of 18 could be scored for each molar (six sextants with a maximum score of 3 each). A score of 8 localized to the buccal and lingual surfaces is considered the minimum to proceed with restorative treatment without crown lengthening. However, as of this writing, the TRI has not yet been validated.

What is the expected quality of the subsequent restorative treatment?

What is the patient's periodontal status?

The quality of the restorative treatment after completion of the endodontics is a very important factor in the decision-making process. Straightforward restorative treatment by a highly skilled clinician warrants more risk taking with a compromised tooth (Fig 21-6).

Patients with poor oral hygiene and/ or poor periodontal support are at increased risk for tooth loss. Deep pock ets, bone loss, mobility, inflammation, and infection—all associated with periodontitis—are negative prognosticators for tooth retention. The long -term effects of poor oral hygiene on implants are not really known at this point but are generally considered to be less deleterious

What is the risk of retaining the tooth? The clinician needs to consider how a retained tooth that fails a few years later will impact future restorative treatment. Figure 21-7 shows an example of a tooth with a fracture line that lasted 4 years but made the future implant treatment more difficult and more expensive.

than for natural teeth.

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Evaluating Restorability Prior to Treatment i

\ Fig 21 - 4 (a to d ) Radiographs and clinical photographs showing the favorable outcome of

conservative treatment through a recent crown.

Fig 21- 5 (a and b ) Vertical crack in relation to a large pin-retained restoration.

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Fig 21- 6 (a and b) Endodontic treatment was completed on the mandibular left first premolar in a patient with very poor- quality restorative treatment. (c and d ) Six months later, the second premolar fractured and had to be extracted. The decision was made to also extract the first premolar, despite the fact that the periapical radiolucency appeared to be healing, and replace both teeth with implant -supported crowns. The decision to extract was partially due to the poor fit of the existing crowns and the likelihood that subsequent tooth- borne crowns would fare no better. (Courtesy of Dr Richard Schwartz , San Antonio, Texas.)

Fig 21-7 (a and b) Endodontic treatment was performed on the maxillary left second premolar with a known crack in one of the canals, (c) Six months later, healing was almost complete, (d ) At the 4 -year recall, there was significant vertical bone loss. The tooth was extracted, but the implant site had been compromised. (Courtesy of Dr Richard Davis, San Antonio, Texas.)

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Factors to Consider

Fig 21 - 8 Failure of the pier abutment occurred Fig 21-9 (a ) Endodontic treatment was performed on an abutment tooth through the existing due to fracture after 5 years. The tooth failed partial denture, (b ) The 5-year recall shows successful retention. even though the quality of the endodontic and restorative treatment was good. (Courtesy of Dr Richard Schwartz, San Antonio, Texas.)

Fig 21-10 (a and b) This patient was taking intravenous bisphosphonates. His maxillary left first molar had decay to the bone level and would normally have been extracted. (Courtesy of Dr Richard Schwartz, San Antonio, Texas.)

What are the restorative options if the tooth is extracted?

What is the intended role for the tooth?

When considering retention of a compromised tooth, evaluate the alveolus as a potential implant site and the adjacent teeth for fixed or removable prosthodontics. A poor implant site, for example, pushes the decision toward retention.

As previously mentioned, terminal teeth in the arch have a poorer prognosis, especially when they are abut ments for removable partial dentures. The prognosis is reduced for teeth that serve as abutments for fixed partial dentures and cantilevers as well as teeth with structural compromise. The use of compromised teeth in multitooth reconstructions should be avoided in most cases. On the other hand, if an abutment tooth is part of an existing and otherwise stable reconstruction, greater efforts should be made to save the tooth and the restoration (Fig 21-9).

Is there adjacent tooth support ? The most posterior tooth in the arch " takes a beating," particularly when it is an abutment for a removable partial denture. A compromised tooth with teeth on both sides, on the other hand, is likely to survive longer because of the physical stabilization and sharing of the occlusal load. Pier abutments are generally poor candidates for endodontic treatment (Fig 21- 8).

What is the patient's health status? Health issues occasionally push the decision toward tooth retention. Physicians sometimes recommend against surgery for medically compromised patients and patients who have received radiation to the jaws. The increased use of intravenous bisphosphonates and the associated healing problems after extraction sometimes result in retention of teeth that would otherwise be ex tracted in a normal patient (Fig 21-10).

What is the quality of the remaining root structure? Evaluate the thickness and length of the roots and try to preserve root structure during endodontic and restorative procedures (see chapter 24).

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Evaluating Restorability Prior to Treatment

Fig 21-11 (a and b) Endodontic access on a mandibular molar with a large mesio-occlusodistal restoration revealed a crack in relation to the distal marginal ridge and distolingual canal. Ca(OH) 2, calcium hydroxide; DB, distobuccal. (c and d ) Distal probing depth in relation to the crack was within normal limits (WNL). Treatment was completed after the patient decided to retain the tooth.

MTA repair

Fig 21-12 (a

to c ) A large furcal perforation was repaired with mineral trioxide aggregate (MTA), and endodontic treatment was completed. MB mesiobuccal. (d) The 1-year recall radiograph shows failing treatment

.

What is the overall treatment plan?

Does the patient have any fractured teeth?

The decision regarding a single tooth should never be made in a vacuum. The overall treatment plan must always be considered and may push the decision in either direction. It sometimes makes sense to extract an otherwise treatable tooth because of considerations unrelat ed to the endodontic treatment.

Teeth with fractures that extend into the root canal system are the nemesis of endodontic treatment. A fracture of this type lowers the prognosis for retention, and most (if not all) of these teeth eventually fail. Teeth with no visible bone loss or deep probing may last longer than those with bone loss and deep probing (Fig 21-11). The pretreatment consultation with the patient, during which the clinician explains the risks and benefits of the various treatment options, is the key to making the decision to treat or extract. Fractures cannot be fully evaluated in many cases without removing all the existing restorations. Teeth with horizontal fractures at the base of a cusp generally have a better prognosis than those that extend into a canal.

Does the patient 's age factor into the

equation? Elderly patients are sometimes more inclined to retain compromised teeth rather than go through the restorative expense and effort required if the tooth is extracted. Also, health issues become increasingly influential with age. On the other hand, as previously mentioned, caries becomes more and more of an issue with age, and the patient's ability to tolerate complex treatment decreases with age.

How does previous endodontic treatment affect risk?

What are the patient's desires?

Retreatment involves removal of additional coronal and radicular tooth structure. Therefore, the structural integrity of the tooth should be evaluated before retreatment

The clinicians involved in treatment must evaluate the patient and make their recommendations, but the patient makes the final decision. Finances or other nonclinical factors often influence the final decision. The clinician's responsibility is to inform the patient of the options, help the patient make the decision, and then obtain his or her consent for treatment.

is considered. Some teeth considered for retreatment also come with previous procedural accidents such as

perforations and separated instruments, which lower the prognosis (Fig 21-12).

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Clinical Cases

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Fig 21-13 (a and b ) Preoperative radiographs of the maxillary right and mandibular right first molars, (c to e) Clinical photographs of both molars. ( f ) The decision- making tool was used to evaluate the restorability of the teeth. The decision was made to attempt retreatment because the overall prognosis appeared to be favorable, ( g and h ) On access, deep cracks were noted in both teeth, so both teeth were extracted.

Reducing Risk Factors

Clinical Cases

The prognosis of a questionable tooth can improve if the severity of the risk factors is reduced. Improving the periodontal condition, replacing failing restorations, decreasing the caries risk, and adjusting the occlusion are a few procedures that can enhance the overall prognosis. Communication with the patient and other treating dentists is paramount to reducing risk factors, as the majority of these procedures are not addressed during endodontic treatment.

Case 21-1 The patient in this case was an asymptomatic 60-year- old man who was referred to the author's endodontic prac tice for assessment of the maxillary right and mandibular right first molars for retreatment. A general dentist had completed the previous endodontic treatment on both teeth approximately 5 years earlier, and both teeth were mildly symptomatic (Figs 21-13a to 21-13e). The diagno sis for both teeth was previous root canal treatment and chronic apical periodontitis. The decision- making tool presented earlier in Fig 21-1 was used (Fig 21-13f), and the decision was made to attempt retreatment because the overall prognosis appeared to be favorable.

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EH

Evaluating Restorability Prior to Treatment

)C

Is the occlusion favorable ?

What is the quality of the remaining coronal tooth

Good

structure ?

What is the patient's periodontal status? What is the patient's caries risk ?

^

Has there been any recent restorative treatment?

(

What is the risk of retaining the tooth?

)( )( *

)(

What is the expected quality of the subsequent

X

( What is the quality of the remaining root structure? ) What is the intended role for the tooth ?

What is the patient's health status?

f

Does the patient's age factor into the equation ?

Yes

)( )(

Low

^

Yes

f Favorable *

No Poor Poor

High No Poor

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No ) XUnfavorable

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j

Unfavorable

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Unfavorable

( Favorable [ Favorable ) ( Unfavorable

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)(

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f Favorable ) ( Unfavorable J

What are the patient's desires?

f

Low

X )(

Favorable

)(

Is there adjacent tooth support?

Good

)(

Good

restorative treatment?

What are the restorative options if the tooth is extracted?

(

Yes

Does the patient have any fractured teeth?

j(

Yes

(How does previous endodontic treatment affect risk?J ( Favorable

^

b

^ ^

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Unfavorablej

- shaped radiolucency in relation to the distal root . A parallel Fig 21-14 (a ) Preoperative radiograph of a mandibular left first molar shows a periradicular J tooth, (c) The metal post was removed, and the untreat the of restorability the evaluate to was used tool making metal post was present. (b) The decision year recall radiographs. ed distal canal was prepared (d and e ) Bone healing was noted in the 2 and 5,

some unknown time in the past. A long-standing buccal sinus tract was present. The endodontic diagnosis was previous root canal treatment and suppurative apical periodontitis The tooth was restored with a metal post and gold crown. A large J - shaped radiolucency was present adjacent to the distal root (Fig 21-14a). A root fracture was suspected, but the probing was within normal limits. The patient was concerned about finances and was considering extraction. The risk factors were discussed, and initiation of retreatment was suggested (Fig 21-14b). During the first endodontic appointment, the tooth was disassembled, the post and core was removed, and no cracks were evident internally. There was

On access, a deep vertical root fracture was evident in both teeth (Figs 21-13g and 21-13h). This finding along with the deep probing depths were critical negative factors that influenced the restorative prognosis. Both teeth were then extracted, as the restorability was not predictable and retaining such teeth might further compromise the bone for future implants.

.

Case 21- 2 The patient in this case was a 72-year-old man who was referred for assessment of the mandibular left first molar, which had undergone previous endodontic treatment at

[208]

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The " Decision Points " Approach an untreated canal in the distal root, which was negotiated with hand files (Fig 21-14c). The canals were prepared and filled with calcium hydroxide paste. The sinus tract healed between appointments, which improved the overall prognosis. Retreatment was completed in multiple visits after bone healing was observed over 4 months. The 2- and 5 - year recall radiographs show a successful outcome with complete bone healing (Figs 21-14d and 21-14e). This patient presented with moderate risk factors at the outset of treatment similar to those in Case 1 However, the risk factors were reduced with the initial intervention, which led to signs of healing as the treatment progressed and a successful outcome.

Case 21- 3 A 39-year-old female dentist presented with failing endodontic treatment in the three mandibular right molars. The original endodontic and restorative treatments were 11 years old (Figs 21-15a and 21-15b). She had no symptoms, but there was a buccal sinus tract between the first and second molars and 12-mm probings on the buccal aspect of the second molar, where the tissue looked boggy and red. A large amount of bone loss was evident radiographically. The deep pockets indicated a high probability of a root fracture in the second molar. All three teeth were structurally compromised and appeared to have a guarded long-term progno sis. A computed tomography scan showed that if the molars were extracted, it was likely that there would be adequate bone volume for implants (Figs 21-15 c and 21-15 d). Extraction was recommended as the first choice for treatment, but the patient was anxious to retain the teeth if possible and opted for retreatment and new restorations. A treatment plan was devised that incorporated four decision points:

.

The " Decision Points "

Approach A useful approach to treatment planning and decision-making is the use of "decision points." When a decision point is reached in the treatment plan, the clinician must decide whether to proceed with treatment, stop treatment, or proceed with a different plan. Examples of decision points in endodontics include the following considerations:

1. Determine whether the second molar had a root fracture. If so, all three molars would be extracted because the first molar was more compromised than

the second. 2. The sinus tract must heal. 3. The deep probings must reduce. 4. There must be clear evidence that the periapical bone is healing.

•

Is the tooth restorable after all the restorations are

removed?

•Did a sinus tract heal after initial treatment?

initial treatment eliminate symptoms and/or swelling? •Were deep periodontal pockets reduced between appointments?

•Did

Retreatment of the second molar was initiated, and no cracks were evident internally (decision point no. 1). The post was removed from the first molar, the gutta percha was removed from all canals in the first and second molars, and these canals were prepared and filled with calcium hydroxide paste (Figs 21-15 e and 21 -15f). The third molar was planned for extraction. The patient returned after 1 month (Figs 21-15g and 21-15h), and the sinus tract had healed (decision point no. 2). The buccal gingiva looked healthier; initially it ap peared that the deep probings were reduced, but when probing was repeated after administration of local anesthesia, there were still deep pockets. The canals were instrumented and irrigated, and fresh calcium hydroxide paste was placed. The patient returned at 3 months (Figs 21-15i), and

In some cases, a decision point may be whether the bone shows initial or complete healing. Decision points allow you to evaluate the prognosis as the treatment plan progresses, and they have predefined criteria that may lead you to "pull the plug." They are also very helpful in communicating the treat ment plan to patients and other treating doctors and explaining the pitfalls that may lie ahead. The following case example shows how decision points were used with a patient with failing endodontic treatment in teeth that were structurally compromised.

there were no deep probings with anesthesia (decision point no. 3). There was some indication that the periapical bone was starting to fill in. The calcium hydroxide was again replaced. At 5 months (Figs 21-15j and 21-15k), the periapical bone was clearly healing (decision point no. 4), there were no deep probings, and the sinus tract had not returned. The calcium hydroxide was replaced one last time.

[209] 由　扫描全能王　扫描创建

Evaluating Restorability Prior to Treatment

Fig 21-15 (a and b) Preoperative periapical radiographs show structural compromise and extensive periradicular bone loss associated with the first and second molars as well as a threaded post in the mesial root of the first molar, (c and d ) A computed tomography scan shows a more accurate estimation of the bone loss but a favorable site for implant placement, (e and f) The post was removed from the first molar, the gutta-percha was removed from both molars, and calcium hydroxide paste was placed in the canals. No cracks were evident internally, (g and h ) At 1 month, the calcium hydroxide was replaced. The sinus tract had healed, (i ) At 3 months, the 12-mm probings were reduced to 4 mm or less, and there was some evidence that the periradicular bone was healing, (j and k) At 5 months, the bone was clearly healing. (I and m ) At 7 months, the bone was almost completely healed radiographi cally. Endodontic treatment was completed, the crowns were cut off , and core buildups were placed with a fiber post in the distal roots and bonded composite resin. The teeth were roughprepped. (n and o) Thirteen-month recall. The third molar has been removed. The bone has healed, and the teeth have been restored with crowns. (Courtesy of Dr Richard Schwartz, San Antonio, Texas.)

-

At 7 months, the bone was almost completely healed radiographically. The canals were obturated, the crowns were cut off, core buildups were placed, and the teeth were rough- prepped (Figs 21- 151 and 21-15m). Figures 21-15n and 21-15 o show the healed periapical bone and the teeth restored at 13 months. The third molar was extracted prior to placement of the crowns. This patient had a number of negative prognosticators for retreatment: structural compromise in the coronal

and radicular tooth structure of both teeth, including a threaded post in the mesial root of the first molar; deep probings and a sinus tract; a possible crack; and extensive periradicular bone loss. On the other hand, she had excellent oral hygiene, a high dental IQ, an endodontist who could restore the teeth immediately after completion of the endodontic treatment, and access to quality definitive restorative treatment. The measured decision point process helped optimize the probability of success.

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Recommended Reading

Summary

Recommended Reading

With the emergence of implants into the mainstream of dentistry, increased emphasis has been placed on longterm outcomes and on evaluating the restorability of teeth prior to endodontic treatment. The team of clinicians treating the patient must weigh the treatment options based on the risk factors for that individual patient. A decision - making tool was provided in this chapter that can aid the decision -making process and case presentation. A decision points approach was described that allows a clinician to evaluate prognosis as the treatment plan progresses based on predefined criteria.

Bandlish RB, McDonald AV, Setchell DJ. Assessment of the amount of remaining coronal dentine in root -treated teeth. J Dent 2006;34:699-708.

Iqbal MK, Kim S. A review of factors influencing treatment planning decisions of single- tooth implants versus preserving natural teeth with nonsurgical endodontic therapy. J Endod 2008;34:519-529.

Iqbal MK, Kim S. For teeth requiring endodontic treatment, what are the differences in outcomes of restored endodontically treated teeth compared to implant -supported restorations? Int J Oral Maxillofac Implants 2007;22(suppl):96-116. Nagasiri R, Chitmongkolsuk S. Long- term survival of endodontically treated molars without crown coverage: A retrospective cohort study. J Prosthet Dent 2005;93:164-170. Ree M, Schwartz RS. The endo-restorative interface: Current concepts. Dent Clin North Am 2010;54:345-374. Ree M, Schwartz R. Management of perforations: Four cases from two private practices with medium- to long- term recalls. J Endod 2012;38:1422-1427. Reeh ES, Messer HH, Douglas WH. Reduction in tooth stiffness as a result of endodontic and restorative procedures. J Endod 1989;15:512-516. Smith CT, Schuman N. Restoration of endodontically treated teeth: A guide for the restorative dentist. Quintessence Int

1997;28:457-462. Zitzmann NU, Krastl G, Hecker H, Walter C, Weiger R. Endodontics or implants? A review of decisive criteria and guidelines for single tooth restorations and full arch recon structions. Int Endod J 2009;42:757-774.

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CHAPTER

Rahim Karmali, DDS

The Pre- endodontic

Teeth are often structurally compromised by the time they need endodontic treatment. This struc tural compromise can be the result of caries, cracks, and/ or large existing restorations. Predictable endodontics requires effective disinfection of the root canal system, and this can only be accomplished with good isolation. Contamination of the root canal system during or after the completion of endodontic treatment can lead to a less than optimal result. Whenever possible, it is advisable to remove all of the existing restorations to assess the tooth for cracks, caries, leakage, and restorability. Caries and stain should be removed until clean, solid den tin is exposed that is suitable for bonding. The structural integrity of the tooth should be assessed, especially the quality of the cervical dentin, which is one of the keys to longevity. The patient does not benefit from successful endodontic treatment if the tooth is lost due to structural or restorative failure. Once the tooth has been deemed restorable, a strategy must be developed for isolation. In the case of multivisit endodontics, this is particularly critical. With deep margins, effective single tooth isolation with rubber dam may not be possible. Multitooth isolation may be possible with a va riety of barrier techniques (see chapter 23). One option is a pre- endodontic buildup with composite resin or resin-modified glass-ionomer (RMGI) cement. If clinicians have knowledge of materials and procedures, the proper armamentarium, and good clinical skills, placing a pre-endodontic buildup can be a straightforward and efficient way to simplify endodontic treatment and enhance predict ability. Placement of a pre -endodontic buildup has several advantages:

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Method 1

Box 22-1

The clinical procedure for method 1 of the pre- endodontic buildup

1. Multitooth isolation is usually preferred. 2. All restorative materials and caries are removed, and restorability is assessed. 3. Fluid and soft tissue control is obtained. This may be accomplished with some combination of anesthetic with 1:50,000 epinephrine, retraction cord, cotton pellets impregnated with epinephrine or coagulants, electrosurgical cautery devices, or lasers. 4. A matrix band is placed. If the pulp chamber is exposed, Cavit (3M ESPE) or a sponge will protect the chamber from filling with composite and make the chamber more easily accessible in subsequent steps. 5. The dentin and enamel are etched with phosphoric acid and thoroughly rinsed to prepare the enamel and dentin surfaces for bonding. The dentin is left moist. 6. A dentin primer and adhesive are placed and polymerized following the manufacturer's instructions. 7. The dual-curing composite buildup material is mixed, placed, and light polymerized.

•It facilitates isolation during the endodontic procedure. •It

provides convenient and reproducible reference

points. •It facilitates a coronal seal during multivisit treatment. •It expedites access closure after completion of endodontic treatment. •It allows long-term provisionalization to assess healing. •It allows gingival healing prior to crown preparation and impression. •It allows the definitive buildup to be placed under ideal isolation.

This chapter describes two methods for placing a pre-endodontic buildup.

Method 1 Method 1 utilizes composite resin and is best for teeth with margins that are easily isolated and fluids that are easily controlled. A dual-curing composite buildup material is used in combination with a dual-curing dentin bonding system. Dual-curing materials contain two components that must be mixed prior to application: ( 1 ) a light-curing component that polymerizes rapidly when a curing light is applied and (2 ) a chemical-curing compo nent that polymerizes slowly in the areas with poor light

8. The matrix is removed, and the composite is polymerized again with the curing light. 9. The buildup is shaped and finished with carbide or diamond burs. 10. The pulp chamber is re-accessed immediately through the pre-endodontic buildup, and endodontic treatment is performed in a secure, well-isolated field. The access can be closed with a temporary material if multivisit treatment is performed. 11. After obturation, the access is closed with composite resin or a post /composite. Some bonding will occur between the old and new composite resin. If a solid, onepiece buildup is preferred, the pre-endodontic buildup can be removed and replaced. An alternative is to leave a thin shell on the periphery to act as a matrix. This peripheral matrix will be removed during the subsequent crown preparation.

penetration, such as a canal space. Most dual- curing composites are provided in a " gun " with an automix tip, while most dual-curing dentin bonding agents are provided in two bottles and you mix a drop of each together. If you always use etch -and-rinse dual-curing bonding agents, you will avoid the compatibility issues present between dual- curing composites and some bonding agents).

Clinical procedure Box 22-1 outlines the clinical procedure for method 1 of the pre- endodontic buildup.

Case report The patient in Fig 22-1 presented with failing root canal treatment and a history of intermittent pain and swelling associated with the mandibular right first molar. He stated that the original endodontic treatment and crown were about 15 years old and that a buccal space swelling was resolved with antibiotics about a year earlier. Radiographically, there was a diffuse periradicular radiolucency with furcation involvement (Fig 22-1 a). The distal canal contained an active metal post. The canals appeared to be underprepared. The crown appeared

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E3

The Pre -endodontic Buildup

Fig 22-1 (a ) Preoperative radiograph. The mandibular right first molar had a periradicular radiolucency, and restorability was questionable, ( b ) The crown was removed, and leakage and decay were evident, (c) Restorability was assessed after removal of all caries and restorative materials (d ) A sponge was placed in the distal canal to expedite re-access, (e) Access was made through the pre -endodontic buildup, ( f ) The pre-endodontic buildup provides a well- sealed, long-term provisional restoration as healing is assessed. Calcium hydroxide is shown in the canals, ( g ) The molar is shown after obturation and prior to definitive closure, (h) Postoperative radiograph. Note that evidence of bone healing was present before completion of obturation and restoration, (i ) The 1 -year recall radiograph shows that the tooth has been restored and bone healing is nearly complete. ,

to be leaking. The patient was presented with two options: retreatment or extraction. He elected retreatment to preserve his natural tooth. The author recommended multiple-step retreatment over a period of several months to delay obturation until the initial signs of osse ous regeneration were evident. At the initial visit, the leaking crown was sectioned and removed. Leakage was noted on the distal margin of the buildup (Fig 22- 1b). The buildup and all caries were removed with the aid of a caries detector under microscopic magnification. The active post was removed with direct ultrasonics No cracks were noted. A sponge was placed in the distal canal (Fig 22-1c). The tooth was etched

and rinsed prior to bonding (Fig 22-1 d), and a bonded buildup was placed with a dual-curing material following standard methods. The pre- endodontic buildup was reaccessed, and the gutta-percha was removed (Fig 22- 1e). A deep split was noted in the distal canal, and the distolingual branch was previously untreated. Patency was established in the mesiobuccal canal, but patency was not achieved in the remaining canals. Calcium hydroxide was placed into the canals. Cavit (3M ESPE) was placed in the chamber, and a 1-mm layer of unbonded flowable composite was placed over the Cavit (Fig 22-1f).

.

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Method 2

Box 22- 2

The clinical procedure for method 2 of the pre-endodontic buildup

1. Multitooth isolation is usually preferred. 2. All restorative materials and caries are removed, and restorability is assessed. 3. Fluid and soft tissue control is obtained. Although placement of RMGI is less technique-sensitive than resin bonding, soft tissue and fluid management are still extremely important. 4. A matrix band is placed. If the pulp chamber is exposed, Cavit or a sponge will protect the chamber from filling with restorative materials and makes the chamber more easily accessible in subsequent steps. 5. The dentin is cleaned and lightly etched with a weak acid (usually a poly acid), rinsed, and left slightly moist. 6. The RMGI is mixed per the manufacturer's instructions and placed in a needle tube syringe. The matrix is filled and light polymerized.

7. The matrix is removed, and the material is light polymerized again, trimmed, and finished. 8. The chamber can then be re-accessed, and endodontic treatment can proceed in a well-controlled field. 9. Once endodontic treatment is complete, part of the RMGI is removed, leaving 3 mm of material covering the deep margins. A thin peripheral shell can be maintained to act as a matrix. This peripheral shell will be removed in the subsequent crown preparation. 10. After obturation, the access is closed with composite resin or a post/composite, leaving 3 mm of RMGI in the areas with the deep margins.

At the second visit 4 weeks later, all symptoms had resolved. The pre- endodontic buildup was reaccessed, and patency was established in the remaining canals. Fresh calcium hydroxide was placed in the canals, and the access was provisionalized as previously described. At the third visit 3 months later, the patient was still asymptomatic, and osseous regeneration was evident radiographically. The pre - endodontic buildup was reaccessed, and the canals were obturated. A stainless steel post was placed into the existing distal post space. The access was definitively closed with a bonded com posite core (Figs 22-1g and 22- 1 h). The 1-year follow -up radiograph showed that osseous regeneration was nearly complete (Fig 22-1i). The adjacent teeth were also re stored in the interim period.

RMGIs contain glass-ionomer cement that undergoes a slow chemical setting reaction and a light-curing resin component that allows immediate polymerization. A dentin bonding agent is not necessary with these materials, and as a result, placement is less techniquesensitive with fewer steps. A low coefficient of thermal

Method 2

The patient in Fig 22-2 presented with spontaneous pain and tenderness in the maxillary right quadrant. Comprehensive endodontic testing isolated the first premolar as the source. Clinically, the existing amalgam restoration was found to be leaking, and radiographically there was a large periapical radiolucency. Caries was also noted in multiple teeth in the quadrant (Fig 22-2a). The restoration and caries were removed from the first premolar under rubber dam isolation. No cracks were noted. Because of the high caries index and deep distal margin, the author decided to place an open sandwich buildup. A matrix was placed, and the preparation was

expansion and low polymerization shrinkage contribute to their good clinical track record.

Clinical procedure Box 22-2 outlines the clinical procedure for method 2 of the pre-endodontic buildup.

Case report

Method 2 utilizes an " open sandwich" layered technique with RMGI in the deep box and composite resin making up the bulk of the buildup. This technique takes advantage of the best properties of both materials. RMGI bonds directly to dentin, requires no bonding agent, and is less technique-sensitive than composite resins. It is cariostatic for a period of time because it releases fluoride, but it is not very strong. Composite resin provides greater strength and durability.

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EE3

The Pre -endodontic Buildup

Fig 22-2 (a ) Preoperative radiograph shows a large periapical radiolucency associated with the right maxillary

first premolar, (b) The existing amalgam restoration and all caries were removed, and a matrix band was placed. (c ) The RMGI pre-endodontic buildup was placed and re-accessed, (d ) Endodontic treatment was completed, and most of the RMGI was removed, leaving 3 mm of material in the deep proximal box and leaving a thin interproximal shell of the RMGI to act as a matrix. This interproximal shell was later removed as part of the definitive crown preparation, leaving an open sandwich buildup. (e ) The diagram shows the components of a preendodontic buildup using the sandwich technique. 1, glass ionomer ; 2, composite resin buildup; 3, red line denotes cementoenamel junction, (f ) The definitive buildup is shown, with two fiber posts and composite resin. ( g ) The postoperative radiograph is shown.

conditioned with polyacrylic acid (Fig 22-2b). An RMGI pre-endodontic buildup was placed and re-accessed (Fig 22-2c). The canal system was shaped and cleaned to patency. Purulent drainage was observed. Once the drainage stopped, the canals were irrigated and dried, calcium hydroxide was placed in the canals, and the ac cess was closed with Cavit and flowable composite as

re- accessed, the calcium hydroxide was removed, and the canal system was obturated with gutta -percha. Most of the RMGI was removed, leaving a 3 - mm thickness in the deep distal box. A thin interproximal shell was maintained to act as a matrix for the composite resin (Fig 22-2d). Two fiber posts were cemented at their deepest passive depth, and a bonded composite core was placed (Figs 22- 2e and 22- 2f). The postoperative radio graph shows signs of osseous regeneration (Fig 22-2g) The thin interproximal shell will be removed when the tooth is prepared for a crown.

previously described. At the second visit 4 weeks later, the patient was asymptomatic. Percussion, palpation, and pressure tests were comparable to the adjacent teeth. The tooth was

.

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Summary

Summary

Clinical tips

In most cases, placement of a pre-endodontic buildup is straightforward and predictable in a field that is already

•Use only composite materials that are recommended by the manufacturer for the purpose of buildups. For example, flowable composites should not be used. •For excellent control in application of the dual-

isolated with a dental dam. Pre- endodontic buildups can help the dentist meet the biologic and mechanical imperatives to achieve excellence in both endodontics and

curing composite core or RMGI, a needle tube syringe can be used. •Utilize an anesthetic with 1:50,000 epinephrine prior to rubber dam isolation to help control soft tissue bleeding around the deep margins. •The gingival tissue can be carefully cauterized with a heat source (System B or Touch'n Heat, Sybron) to obtain better isolation and soft tissue control. •With the open sandwich technique, a thin layer of RMGI can be left in the interproximal area to act as a matrix when placing the composite core layer to mitigate the need for another matrix. The interproximal RMGI should be thin enough that it is removed during subsequent crown preparation.

restorative dentistry.

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CHAPTER

Michael Trudeau, DDS

The Customized IreMTilAEifTC

Teeth requiring root canal treatment often have significant loss of tooth structure. Once endodontic therapy is complete, for optimal outcomes, the tooth should be restored immediately with a high - quality restoration. Nothing positive occurs when the restoration is delayed. The restorative procedure is sometimes more challenging than the endodontic treatment, particularly if there are deep finish lines and isolation is difficult. Regardless of the type of restorative material, good isola tion and appropriate tooth form are required. To accomplish these goals, it is important to choose the correct matrix for the given situation. This chapter introduces the customized resin matrix, a technique that may be used with any restorative material and is particularly effective in the most

difficult restorative situations. A stainless steel matrix band used in conjunction with a Tofflemire retainer is probably the most common matrix system for posterior teeth (Fig 23-1). This solution works well for the vast majority of restorative cases to restore the tooth to proper form and function (Figs 23 - 2 and 23- 3). However, matrix bands have their limitations. Isolating deep margins, for example, can be a problem . Terminal teeth in an arch can also be problematic, because the rubber dam clamp sometimes prevents complete seating of the matrix band. Tofflemire matrices are of limited use for teeth with previous crown preparations or severe breakdown. Copper bands are sometimes useful for these situations (Fig 23 -4), but trimming and fitting them can be difficult and frustrating. In many difficult restorative situations, a light -cured composite resin is the best option to create a matrix. The author utilizes OpalDam (Ultradent) to build a sectional or circumferential resin wall

H HKiH ST

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Armamentarium

-

—

Fig 23 - 1 A Tofflemire retainer with metal matrix bands.

Fig 23- 4 Copper bands can be used as a matrix for severely broken-down teeth.

Fig 23- 2 (a ) A maxillary first molar with a metal matrix band in place, (b) The resulting mesio-occlusolingual amalgam core.

Fig 23- 5 A tube of green OpalDam resin.

Fig 23- 3 A postoperative periapical radiograph of a tooth restored with amalgam using a Tofflemire retainer with a metal matrix band.

Fig 23- 6 Orange-filtered protective eyewear that allows the clinician to visualize the light -curing process without eye damage.

•Protective colored glasses (Fig 23-6): To expedite ap-

around the tooth to act as a matrix (see Fig 23-5). Isolation for the surgical repair of invasive cervical resorption (ICR ) ( see chapters 28 and 29) is another good indication for a resin matrix. In some cases, it is the only method available to provide a clean, dry field for bonding procedures. The purpose of this chapter is to describe the resin matrix technique and present several clinical scenarios in which it can be used.

plication of the OpalDam, it is advantageous to cure the resin as it is expressed. (The author wears special orange-filtered glasses for eye protection to allow him to view the OpalDam as it is expressed and polymerized

simultaneously.) •Viscostat (Ultradent) (Fig 23-7): A hemostatic liquid applied with a syringe •0.014 Crown and Bridge Bur (Patterson) (Fig 23-8) •Munce Discovery Bur #4 (CJM Engineering) (Fig 23-9) •Interdental Proxabrush (GUM) (Fig 23-10) •Black 20-gauge syringe tips (Fig 23-11): 20-gauge tips are ideal for applying the OpalDam. (Some tips have a translucent plastic housing so that if you polymerize the resin as it is dispensed, which saves time with large matrices [ see Case 23-1], the resin polymerizes within the tip. To overcome this problem, the author paints the tips with black fingernail polish.) •Peeso bur (Fig 23-12)

Armamentarium The armamentarium required for building a resin matrix includes the following:

•OpalDam (Fig 23-5): A light-cured resin block-out and matrix material

•A curing light

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E3

The Customized Resin Matrix

Fig 23- 7 Viscostat is typically sold in a bulk tube. It can then be transferred into generic 3 - mL syringes and fit ted with a tufted tip for clinical application.

Fig 23- 8 0.014 Crown and Bridge Bur.

Fig 23- 9 A # 4 Munce Discovery Bur.

Fig 23-11 Syringe tips (20-gauge) painted with black nail polish to prevent the resin from curing within the tip if it is dispensed and cured simultaneously.

Fig 23-10 A flexible interdental brush for postoperative management of the gingivectomy site.

Fig 23-12 A # 2 Peeso drill with the tip cut off. These drills are an effective way to sever the gutta-percha apical to the orifice level and create areas for core retention.

4. Scrub the bone and soft tissue with a tufted scrub tip with Viscostat Clear for 30 seconds, applying significant pressure. Rinse and dry. There should be no active bleeding or crevicular seeping (Fig 23-13b). If there is any bleeding, either remove additional gingival tissue or repeat the Viscostat scrub until there is good mois ture control. 5. Apply a 1- to 2 mm layer of green OpalDam with a 20-gauge tip on the bone and gingiva around the tooth. Cure for 10 seconds (Fig 23-13c). 6. If a circumferential matrix is needed, build an OpalDam wall in increments with 10-second light cures until the wall extends coronally to the desired height for the re storative core (see Case 23-1). 7. Remove any OpalDam flash that covers tooth struc ture with a # 4 Munce Discovery Bur and /or the 0.014 Crown and Bridge Bur (Fig 23-13d). 8. Using the 0.014 bur, smooth the internal form of the matrix and finalize the core form (see Case 23 ) -1 . 9. Provide the appropriate chamber cleanup, and place a core buildup with either a bonded amalgam or composite resin material.

Resin Restorative Matrix Technique for a Core Buildup The technique for building a customized resin matrix for a core buildup is as follows:

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1. Complete root canal treatment. 2. Perform a localized gingivectomy, if necessary, with a diamond bur (the author uses a 0.014 Crown and Bridge Bur) to expose the tooth margin. The goal is to expose at least 1 mm of vertical tooth structure apical to the finish line. Remove the tissue to the level of the bone, if necessary. Perform this procedure without water, because the heat will cauterize the tissue and decrease bleeding. Often little brown blebs of cauterized tissue are left behind (Fig 23-13 a). 3. Remove bone, if necessary, with water spray. Water will cool the bone during the osteotomy and prevent tissue necrosis. The tissue must be 1 to 2 mm below the cavosurface margin of the restoration when this procedure is complete (see Fig 23-13a).

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Clinical Cases

Fig 23-13 (a ) The interproximal tissue after gingivectomy but before Viscostat application is usually hemorrhagic, (b) After the Viscostat “scrub,” the field is well managed with no bleeding and is ready for OpalDam resin application, (c ) A layer of OpalDam resin is placed over the tissue/bone and polymerized. Additional resin is placed to the buccal and lingual to form a matrix for the amalgam. The tooth is now ready to receive the amalgam. (d) An interproximal pass is made with a 0.014 bur to remove the excess amalgam, (e) The remaining OpalDam matrix is removed with a spoon, (f ) The finished core after final shaping with an interproximal carver. ( g ) A postoperative periapical radiograph depicting a properly placed amalgam core.

10. Once the amalgam has an initial set, pass a 0.014 bur

Clinical Cases

through the interproximal area to remove the excess amalgam and most of the green matrix. Use a spoon excavator to remove any pieces of OpalDam that remain (Fig 23-13e). The initial set may take as long as 8 minutes, depending on the amalgam. Spherical alloys tend to set faster. As your experience with the procedure increases, you may choose to start removing the matrix before the amalgam is hard, but this requires a light touch to avoid " dings" or fracture of the amalgam. If composite is used, wait until it is completely cured. The OpalDam may adhere to the core, but its green color makes it easy to distinguish from the core composite. 11. Finish the restoration and rinse thoroughly to remove any debris (Figs 23-13f and 23 -13 g). A finish line may be placed on tooth structure in deep areas (see Case 23 - 4). In some cases, the finish line in deep areas may be placed on amalgam. 12. Provide postoperative instructions, including brushing the site with chlorhexidine until the restorative appointment. An interdental brush works particularly well.

Case 23-1: Bonded amalgam in a mandibular molar with severe breakdown A 64-year- old woman presented after the crown came off her mandibular left first molar. The preoperative ra diographs showed a terminal mandibular molar with significant missing tooth structure (Fig 23-14a). Root canal treatment was performed. At the first appointment, the canals were instrumented and medicated with calcium hydroxide. At the second appointment, the root filling was placed, all of the provisional restorative material was removed, and a gingivectomy was performed on the distal aspect of the tooth with a high-speed handpiece and the course - grit 0.014 bur without water. The frictional heat cauterized the tissue. The gingivectomy was extended just beyond the line angles and 1 to 2 mm apical to the cavosurface margin. A 30-second scrub with Viscostat Clear was then performed. After rinsing, the field was well controlled (Fig 23-14b). Good hemostasis is important before proceeding with the resin application, and the cavosurface must be dry. A circumferential matrix was needed for this tooth. An initial layer of the green resin was applied circumferentially and polymerized for 10 seconds. Completed poly-

Variations of this basic technique are illustrated in the case reports that follow.

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The Customized Resin Matrix

Fig 23-14 (a ) The crown was dislodged, and there was recurrent caries underneath, (b ) A g:ngivectomy was performed on the distal aspect of the tooth, (c) The first layer of OpalDam was applied to the data! aspect and polymerized, (d) The mesial wall of the matrix (e) The distal wall of the matrix, (f ) The occlusal view of the entire customized resin matrix. ( g ) The amalgam was packed to the full height of the matrix, ( h ) The final amalgam core. (i ) A postoperative periapical radiograph of the completed endodontics and core. ,

merization at this point in the treatment is not necessary (Fig 23 -14c ). Then the remaining walls of the matrix were built continuously (Figs 23-14d to 23-14f). The matrix was refined, any flash was removed, and the amalgam was packed to the full height of the matrix (Fig 23 -14g). After the amalgam had set, the green matrix was removed with the 0.014 bur, and the tooth was roughprepped for a crown. Debris was removed from the tissues with water spray (Figs 23-14h and 23 -14i).

canal treatment and restoration of both teeth, but only the molar is discussed here. After removal of the crown, significant caries was observed on the distal and palatal aspects of the molar. Access was made into the distal canal through the distal area of caries removal, and a separate access was made to instrument the mesial canals. Access preparation that retains a dentin “truss" probably results in a stronger tooth than a traditional access preparation and provides retention form for the core (see chapter 8). A gingivectomy was performed using the 0.014 Crown and Bridge Bur, leaving at least 2 mm of tooth structure above the level of the bone. Hemostasis was achieved using a Viscostat scrub. An initial layer of OpalDam resin was placed on the bone from the mesiobuccal line angle to the distobuccal line angle of the prepared tooth. A continuous cure of the OpalDam was then applied, building a full-contour wall around the palatal aspect of the tooth. Placing and condensing amalgam from the palatal and distal aspects presents a challenge with a copper band or other matrices. In this case, the matrix was customized to facilitate the condensing of amalgam. After the OpalDam wall was built, it was flared using the

Case 23- 2: Bonded amalgam in a maxillary molar with severe

breakdown A 50-year-old woman presented with a painful response to cold at the maxillary left first molar and percussion tenderness at the adjacent premolar. The bitewing radiograph showed recurrent caries under the distal crown margin of the molar (Fig 23-15a). The periapical radiograph showed a

molar with normal periapical findings and typical root morphology and a periapical radiolucency associated with the premolar (Fig 23-15b). The treatment plan included root

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Clinical Cases

Fig 23-15 (a ) The preoperative bitewing radiograph suggests recurrent caries in the maxillary left first molar (b) The preoperative periapical radiograph ,

shows normal periapical areas around the first molar but chronic apical periodontitis associated with the second premolar, (c) The completed customized aliquots of ,( ) resin matrix. Note how the mesial and distal canal systems have separate points of access with a “truss" of retained dentin in between d The first matrices, (e) amalgam being placed into the matrix are easily accessed from a divergent matrix. Access probably would have been a problem with traditional and core. Occlusal view of the palatal aspect of the amalgam core. (f ) Postoperative periapical radiograph of the maxillary molar with completed endodontics . (g) Two-week postoperative follow-up showing typical gingival healing if the patient follows the recommended postoperative instructions

benefits, and alternatives were discussed, and consent was obtained from the patient. Through an incisal access preparation, root canal treatment was completed in two appointments. The buccal canal was chosen for post placement so that it would approximate the resorption and was restored with a 0.5 DT Light-Post (Bisco) fiber post (Figs 23-16c and 23-16d). Small releasing incisions were made, and a full-thickness flap was reflected to include the adjacent teeth and papillae. The extent of the resorption was appreciated and then debrided with a 0.014 diamond bur. Once the resorptive granulation tissue was grossly removed, a judicious amount of Viscostat Clear was used on the 1 to 2 mm of tissue surrounding the cavity preparation. When the immediate field was dry, an initial layer of OpalDam was applied, leaving a small margin of root surface exposed around the preparation, and light cured. Additional layers of OpalDam were then applied to make a 3 X 3-mm matrix around the cavity preparation. At this point, 90% aqueous trichloroacetic acid (TCA) was applied to the cavity preparation using a small cotton ball (Fig 23-16e). After rinsing, minute resorptive tracks could be appreciated under high magnification. These were targeted with a VA Munce Discovery Bur. Additional applications of TCA were applied, followed by more targeted drilling. The internal cavity preparation was then refreshed with a # 4 Munce Discovery Bur,

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Crown and Bridge Bur (Fig 23 15c). This allowed for easier manipulation of amalgam under the truss and around the palatal aspect of the tooth (Fig 23-15d). After a 5-minute set time for the amalgam, the green OpalDam was removed using the 0.014 Crown and Bridge Bur. The crown preparation was finalized (Figs 23-15e and 23-15 f). An interdental brush was dispensed to the pa tient, and a chlorhexidine rinse was prescribed. At the 2-week follow- up, the tissue appeared pink, firm, and fibrotic and ready for the crown impression (Fig 23-15g).

Case 23- 3: A composite resin

restoration in surgical treatment of invasive cervical resorption A 57-year-old woman presented with a chief complaint of increasing cold sensitivity and spontaneous throb-

bing of her mandibular right canine. Diagnostic tests were consistent with irreversible pulpitis and a normal periapex. Radiographs suggested resorption extending 3 to 4 mm apical to the osseous crest (Fig 23 -16 a). Cone beam computed tomography (CBCT) images were consistent with ICR 3 to 4 mm in diameter, extending close of to the buccal canal but not beyond the line angles in was bone of plate ) buccal No the tooth (Fig 23-16b . feature to appeared canal system evidence, and the root Type II anatomy (two canals that join apically). The risks,

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The Customized Resin Matrix

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Fig 23-16 (a ) Preoperative periapical radiograph of the mandibular right canine with evidence of ICR. (b ) A sagittal slice from a focused- field CBCT image depicting the extent of the resorption. (c ) Incisal view of the tooth with the fiber post cemented with LuxaCore resin (DMG America), (d ) The finished and polished definitive composite restoration in place, (e) A buccal flap was reflect ed, an OpalDam matrix was applied to provide isolation, and the ICR was debrided mechanically with a bur and chemically with TCA. ( f ) The final cavity preparation ( g ) The completed composite restoration after finishing and polishing, ( h ) Radiograph of the completed restoration, (i ) The surgical site after suturing, ( j) At the 1.5-year recall, note the gingival position. The sulcus depth was 2 mm adjacent to the restoration, ( k ) Periapical radiograph at the 1.5-year recall. ,

and the cavity was restored with composite resin using standard methods. The completed cavity preparation is shown in Fig 23 -16f. The restoration was shaped with finishing burs, the OpalDam resin matrix was removed, and the restoration was polished (Fig 23 -16 g). A radiograph of the definitive restoration is shown in Fig 23 -16h. The surgical site was irrigated, the flap was replaced to its original position and compressed for 10 minutes, and two interrupted sutures were placed (Fig 23 -16i). Postoperative instructions were given, and prescriptions included chlorhexidine rinse and nonsteroidal anti-inflammatory drug analgesics. At the 1.5 -year recall, the tissue was stable (Fig 23-16j) with 2- mm probings, and the radiograph showed normal periapical architecture (Fig 23-16k).

canals were instrumented and obturated with guttapercha. The distal margin was subgingival (Fig 23-17c). Gingivectomy and ostectomy were performed with a diamond bur as previously described (Fig 23-17d). Viscostat Clear was scrubbed for 30 seconds, and the field was well controlled and dry. The first layer of OpalDam was placed on the bone and cured. The remaining increments were applied until all the local tissue was covered with OpalDam (Fig 23-17 e). With a composite resin restoration, it is not necessary to build the matrix to full contour like it is with amalgam. The author prefers to wait until the field is completely controlled before creating post spaces to avoid introduction of debris into the canals, so at this point the gutta-percha was removed passively from both canals, with no additional removal of tooth structure. The matching DT Light Post for this space was a size 0.5. The canals and tooth were etched, primed, and bonded using standard methods. Microsuction was used to prevent pooling of the bonding agent in the canals. LuxaCore dual-curing composite was delivered with a Centrix syringe into the canals and preparation, and two DT Light-Posts were seated (Fig 23-17f). The composite was light polymerized, and the fiber posts were cut back to the composite. The excess composite was removed from the interproximal area with a pass of the 0.014 diamond bur, and the remaining matrix was removed with a spoon excavator. The green color of the OpalDam

Case 23- 4: Composite resin with a post and core to restore a premolar A 21-year-old man presented with a chief complaint of cold sensitivity in his maxillary premolar. The bitewing and periapical radiographs suggested deep distal caries below the gingiva (Figs 23 -17a and 23-17 b). Endodontically treated premolars and anterior teeth are at risk for " snap-off " failure, so the treatment plan for this tooth included endodontic therapy as well as a post and core. The caries was removed, and the

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Clinical Cases

Fig 23-17 (a) The preoperative bitewing radiograph shows extensive caries in the maxillary second premolar (b) The preoperative periapical radiograph shows normal root morphology, (c) The caries on the distal aspect of this tooth extended below the gingiva, (d) After gingivectomy and localized crown lengthening, the field was dry and ready for the customized resin matrix, (e) The customized resin matrix provided a controlled environment for bonding, (f ) The LuxaCore buildup was completed with two DT Light-Posts, (g ) After the customized matrix was removed, a finish line was placed on tooth structure, and the core was rough-prepped on the distal aspect , (h) Postoperative radiograph showing the final post and core. ,

amalgam restoration. The tooth had extensive occlusal, mesial, and buccal caries (Fig 23-18c), all of which was removed, exposing the pulp (Fig 23-18d). The coronal pulp was removed, and a cotton pellet soaked with lidocaine with 1:50,000 epinephrine was compressed over the bleeding canal orifices for 1 minute. This provided hemostasis and allowed the application of gray MTA (Fig 23-18e). Because the second molar had not erupted, the first molar was the terminal tooth in the arch; however, a rubber dam clamp on the terminal tooth can make it dif ficult to apply a matrix band. Because a cuspal-coverage amalgam restoration was planned as the definitive restoration, it was important to establish a solid mesial contact. A FenderMate (JS Dental) sectional matrix was used. It consists of a thin section of matrix material attached to a wedge (Fig 23-18f). The FenderMate was wedged interproximally, and a customized resin matrix was added on the buccal aspect to create the proper tooth form (Fig 23- 18g). Amalgam was condensed over the MTA to full contour. The FenderMate was carefully removed, and the customized matrix was peeled from the amalgam. The amalgam was then carved to the desired contours and anatomy, completing the cuspalcoverage restoration (Figs 23-18h and 23-180

makes it easy to distinguish it from tooth, bone, and composite so that it can be removed easily. A smooth finish line was prepared in the interproximal area on tooth structure just apical to the composite core (Fig 23-17g). The contact was left completely open, allowing for excellent hygiene with an interproximal brush and facilitating excellent healing, an easier impression, and a more favorable restorative outcome (Fig 23-17h). A brush was dispensed to the patient along with a prescription for chlorhexidine.

Case 23-5: An MTA pulpotomy and a complex amalgam in an immature molar An 8-year-old boy presented with a chief complaint of

associated with his was hypersensitive tooth The . molar maxillary left first significant depicted radiograph to cold. The bitewing radiograph ) The periapical . ( 23 18 a occlusal caries Fig suggested incomplete root development (Fig 23-18b). Based on the maturity of the tooth, the patient 's symptoms, and the tooth vitality, a mineral trioxide aggregate (MTA) pulpotomy was treatment planned. Based on the patient's age and the amount of tooth destruction, it was decided to restore the tooth with a cuspal- coverage spontaneous pain and throbbing

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The Customized Resin Matrix

Case 23-5

Fig 23- 18 (a ) A bitewing radiograph of a maxillary left first molar with significant caries (b ) A periapical radiograph showing incomplete development of the tooth (c) Preoperative photograph of the molar showing significant caries. (d ) After caries removal, the pulp was exposed, (e) The coronal pulp was removed, bleeding was controlled, and MTA was placed in the chamber, ( f ) A FenderMate sectional matrix was used to provide proper interproximal , contours ( g ) The FenderMate in place in conjunction with a customized resin matrix, ( h ) The completed amalgam restoration with a tight mesial contact, (i ) Postoperative radiograph of the MTA pulpotomy with an amalgam core. ,

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Conclusion

easy to learn and can help you to achieve highquality amalgam and composite cores and restorations. The author often uses it in situations where there is biologic width impingement. It can be used in conjunction with traditional surgical crown lengthening or at the same time as localized crown lengthening with a bur.

The resin restorative matrix can be used in most restorative situations, but it is particularly helpful for terminal teeth, teeth with severe breakdown, and situations where isolation is difficult. The procedure is relatively

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CHAPTER

*..Richard ¥

Schwartz, DDS

Restorative Procedures with

Successful endodontic treatment is dependent on the restorative treatment that follows. The restorative treatment contributes to the structural integrity of the tooth and maintains the " clean " status of the root canal system. Recontamination of the root canal system is considered an important factor in late failures. The importance of the coronal restoration has been demonstrated in several studies, and delayed restoration has been shown to result in lower success rates.1^ Conversely, the endodontic treatment influences the prognosis of the restorative procedures. Radicular and coronal tooth structure should be preserved to the greatest possible extent during endodontic procedures. Access preparations should be designed so that cervical dentin is preserved (see chapter 8). The roof of the pulp chamber should be opened only to the extent necessary for access to the canals, and the walls of the pulp chamber should be prepared only to the extent necessary for adequate access for endodontic treatment. Immediate restoration of the tooth following obturation is highly recommended and has a number of advantages: ( 1 ) The operator is familiar with the root canal morphology, working lengths, and reference points of the root canal system; (2 ) the tooth is already isolated, so the chances of contamination are low; (3 ) it is more efficient for the doctor and the patient because the patient is already anesthetized, rubber dam is already in place, and there is no need for a provisional restoration. Posts are generally used for supplemental retention of a core. Recently, fiber posts have also been shown to add stiffness and improve the fracture resistance of teeth. Anterior teeth and premolars often benefit from the placement of a post when they are restored. Little, if any, additional canal preparation should be necessary once the endodontic treatment is complete.5-7 Choose a post that matches the canal in size and taper, rather than removing dentin to make the tooth fit the post (see Fig 24-1).

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Restorative Procedures with Posts

Fig 24- 1 Posts should be selected and adjusted to fit the existing canal space after endodontic treatment is complete. In this case, the canal was enlarged to fit the post, causing a fracture or strip perforation. In addition, note how much radicular dentin was removed from the apical extent of the post because it was parallel and the canal and root were tapered. When the author uses a metal post , he tapers the apical end with a diamond bur and fits it to the existing canal without removing any dentin.

Fig 24- 2 (a and b) A single-rooted fixed partial denture Fig 24- 3 Whenever possible, the auabutment tooth restored with a fiber post and composite resin.

The purpose of this chapter is to (1 ) discuss the role of posts, (2) discuss which type of post is most beneficial in various situations, and (3 ) describe the materials and clinical procedures used with posts.

thor places two fiber posts when restoring access preparations in crowns. This increases retention and resistance to fracture.

Fiber posts are not as strong as metal posts, but they distribute forces more favorably and are less prone to root fractures because they have a modulus of elasticity (stiffness) similar to that of dentin. They are available in various tapers that can be used to match the root canal preparation after endodontic treatment, so no additional dentin removal is necessary. When an access cavity preparation is restored through a crown, there is no way to accurately assess the remaining natural tooth structure. Contrary to the literature from the 1980s and 1990s about metal posts, there are numerous studies in the past 10 years showing that fiber posts strengthen the tooth.8-13 Consequently, the author routinely restores access cavities through crowns with fiber posts in premolars and anterior teeth (see Fig 24- 3). This is especially advisable for single-rooted fixed partial denture abutment teeth (Fig 24-2). Whenever possible, the author places two fiber posts (Fig 24-3). As a general rule, choose a post based on the amount of remaining tooth structure. With adequate remaining coronal tooth structure (1 to 2 mm of vertical and horizontal ferrule on the facial and lingual surfaces), the author uses a fiber post unless the canal size is very small. Teeth with severe compromise of the coronal tooth structure are often recommended for extraction or crown lengthening to obtain an adequate ferrule These teeth are sometimes restored with an active metal post or a custom cast metal post and core. Metal posts should be avoided in roots with thin walls.

Types of Posts and Their Indications Posts can be categorized many different ways, but for our purposes we will limit the discussion by identifying them as either ( 1 ) metal or fiber, (2 ) tapered or parallel, and (3 ) active or passive. The primary benefits of metal posts are strength and stiffness. The need for strength may be the overriding factor in post selection when there is minimal coronal tooth structure or thin canals. However, metal posts have several disadvantages. They concentrate forces less favorably in the root than fiber posts, and they are more susceptible to root fractures Virtually all prefabricated metal posts are parallel, while almost all roots and root canals are tapered. Parallel posts are more retentive, but they also require removal of radicular tooth structure at their apical extent, the primary location where forces concentrate with metal posts ( Fig 24-1) Passive posts are always preferred, but occasionally an active post is necessary for a tooth with short roots where maximum retention is needed.

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Fiber Posts 7. Apply a reducing agent such as 10% sodium ascorbate to the dentin surfaces for 1 minute. This will reverse the oxidizing effects of the sodium hypochlorite and contribute to a stronger bond to the dentin. 8. Acid etch the enamel (if present) with 37% phosphoric acid for 30 seconds and the dentin for 15 seconds (Fig 24-4c), agitate these surfaces with a small tufted brush, rinse, and air- dry with a Stropko Irrigator (Sybron) (Fig 24-4d). 9. Place 2% chlorhexidine in the canal, allow it to soak for 30 seconds, and air-dry until the surface is moist with no pooling. Chlorhexidine is a protease inhibitor that has been shown to slow the degradation of dentin bonding.14 10. Apply the primer from a dual-curing adhesive system to all the dentin surfaces for about 20 seconds and thoroughly air-dry (Fig 24- 4e). 11. Mix and apply a thin layer of dual-curing adhesive to the dentin. Use a paper point to remove excess adhesive from the canal (Fig 24- 4f), and then light polymerize the adhesive. 12. Inject the dual- curing buildup material into the ca nal, seat the post, and polymerize the material with a cure light (Fig 24-4g). 13. With a small round diamond bur, trim away the excess composite and post, creating a 2-mm space for a layer of restorative composite (Fig 24-4h). Make sure that the internal surface of the ceramic material is refreshed and that all the dual-curing resin has been removed from the ceramic (Fig 24-4i). 14. Apply 10% hydrofluoric acid to the internal ceramic surfaces for 1 minute and rinse thoroughly (Fig 24-4j). 15. Scrub the frosty-looking etched ceramic with alcohol (Fig 24- 4k). 16. Apply a ceramic primer to the etched ceramic and air-dry (Fig 24- 4I). 17. Apply a thin layer of dentin adhesive and liqht cure (Fig 24- 4m). 18. Apply a restorative composite resin to the remaining cavity, light cure, finish, and polish (Figs 24- 4n and 24-4o). The author typically uses an egg-shaped, 12-fluted finishing bur and diamond-impregnated low-speed rubber polishing point. 19. Check the occlusion (Fig 24-4p).

Fiber Posts Fiber posts are "cemented" with lightly filled composite resins. Light penetration is limited, so dual-curing or self-curing resins must be used. The term dual-cure means that there are two components that are mixed together prior to placement to allow for light and chemical polymerization. Shallow areas are polymerized rapidly with a curing light, and the areas with little or no light penetration undergo a slower chemical polymerization. The author uses two products to cement posts: a dual-curing dentin adhesive system in combination with a dual-curing buildup material. The buildup material acts as the luting cement for the post as well as the core material, and both procedures are completed at the same time. Some clinicians use separate luting cements and buildup materials. Self-adhesive luting agents have gained popularity for this approach because they do not require a separate dentin adhesive in the post space However, they should only be used for cementing the post and are not

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suitable for use as a core.

Clinical procedures for restoring access preparations with a fiber post and composite resin The clinical protocol for restoring access preparations with a fiber post and composite resin is as follows: 1. Grossly clean the canal with the twist drill that corresponds to the post. Little, if any, dentin should be removed in this process (Fig 24-4a). 2. The remaining remnants of gutta-percha, sealer, and temporary filling materials can be removed with a rotary brush in a low -speed handpiece (Fig 24- 4b) and/or with microbrushes dipped in alcohol or a

detergent. 3. Inspect the internal cavity surfaces under the microscope to make sure that the canal walls are clean

and pristine. 4. Select a post that passively fits into the available ca nal space and prefit it. In oval-shaped canals or pre-

molars with two canals, consider placing two posts. Confirm the fit with a radiograph if necessary. 5. Air abrade the post surface with 50-micron alumina particles for 5 seconds, or use a pretreated post that has been immersed in 24% hydrogen peroxide for 10 minutes. Clean the post surface by acid etching it with 37% phosphoric acid; then rinse and air-dry. 6. Apply silane to the post surface according to the manufacturer's instructions.

Preoperative and postoperative radiographs are shown in Figs 24-4q and 24- 4r, respectively.

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Restorative Procedures with Posts

Fig 24- 4 (a ) Endodontic treatment is complete, and the post space has been created. Note the stepped access (see chapter 8). No additional dentin was removed after obturation (b ) The canal was cleaned with alcohol and a rotary brush, (c) Phosphoric acid was applied to the dentin surfaces for 15 seconds and agitated with a microbrush, (d ) A Stropko Irrigator was used to thoroughly rinse the post space, (ej Dentin primer was applied with a long, thin microbrush, ( f ) Dual- curing dentin adhesive was applied with a microbrush followed by a paper point . Note that the yellow filter was in place to prevent premature polymerization by the microscope light , ( g ) The post space was filled with dual-curing composite, and the post was seated. ( h ) A round diamond bur was used to remove excess composite resin and post material, and a 2- mm space was created for restorative composite. ( i ) Remaining composite flash was removed from the surrounding unetched ceramic with a spoon excavator, ( j ) The ceramic was etched with 10% hydrofluoric acid for 1 minute, ( k ) Note the frosty appearance of the etched ceramic . This should be scrubbed with alcohol to remove residue from the etching process. ( I ) A ceramic primer was applied to the etched ceramic and air- dried, (m ) A dual-curing adhesive was applied and light cured ( n ) The composite was finished back to the margins with an egg- shaped, 12-fluted finishing bur. (o ) The composite was polished with a diamond- impregnated rubber point, (p ) The occlusion was checked, (q ) Preoperative radiograph, ( r ) Postoperative radiograph. ,

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Fiber Posts

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Fig 24- 5 (a ) A Tofflemire matrix applied in preparation for a composite buildup with a post. (b ) A dentin adhesive is applied, and dual-curing composite is injected into the canal space, (c ) The matrix filled with composite and the post in place, (d) The completed buildup, after it is shaped and adjusted, (e and f ) To help the referring doctor, the author sometimes prepares a deep finish line on tooth structure apical to the buildup (under the microscope). ( g ) Preoperative radiograph , ( h ) Postoperative radiograph.

Clinical procedures for fiber post cementation and composite core buildup Many of the procedures for post cementation and buildup are similar to those for restoring an access cavity, with some variation and a few extra steps:

1. Grossly clean the canal with the twist drill that corresponds to the post. Little, if any, dentin should be removed in this process. 2. The remaining remnants of gutta-percha, sealer, and temporary filling materials can be removed with rotary brushes in a low -speed handpiece and/or with microbrushes dipped in alcohol or a detergent. 3. Inspect the internal cavity surfaces under the microscope to make sure that the canal walls are clean

and pristine. 4. Select a post that passively fits into the available canal space and prefit it. In oval-shaped canals or premolars with two canals, consider placing two posts. Confirm the fit with a radiograph if necessary. 5. Air abrade the post surface with 50-micron alumina particles for 5 seconds, or use a pretreated post that has been immersed in 24% hydrogen peroxide for 10 minutes. Clean the post surface by acid etching the surface with 37% phosphoric acid; then rinse and air-dry. 6. Apply silane to the post surface according to the manufacturer's instructions. 7. Place a matrix band and secure it (Fig 24- 5 a).

8. Apply a reducing agent such as 10% sodium ascorbate to the dentin surfaces for 1 minute. This will reverse the oxidizing effects of the sodium hypochlorite and contribute to a stronger bond to the dentin. 9 Acid etch the enamel (if present) with 37% phosphoric acid for 30 seconds and the dentin for 15 seconds, and then rinse and air-dry with a Stropko

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Irrigator. 10. Place 2% chlorhexidine in the canal and on the internal dentin surfaces, allow it to soak for 30 seconds, and air- dry until the surface is moist with no pooling. 11. Apply the primer from a dual-curing adhesive sys tem to all the dentin surfaces for about 20 seconds and thoroughly air-dry. 12. Mix and apply a thin layer of dual-curing adhesive to the dentin. Use a paper point to remove excess ad-

hesive from the canal. Polymerize the adhesive with the curing light. 13. Inject the dual-curing buildup material into the canal and matrix (Fig 24-5b), seat the post, and polymerize the material with a curing light (Fig 24-5c). 14. Remove the matrix, and trim and shape the buildup with finishing burs (Fig 24- 5d). In some cases, the author does a rough crown preparation at this point or places a finish line on tooth structure in deep areas apical to the buildup (Figs 24-5e and 24-5 f). 15. Apply light polymerization from three directions.

Preoperative and postoperative radiographs are shown in Figs 24- 5 g and 24-5h, respectively.

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m

Restorative Procedures with Posts

Fig 24- 6 (a ) The completed preparation with two post spaces and the matrix in place, (b) The cement ed posts are shown after chamber cleanup. A dualcuring dentin primer and adhesive were then placed and light polymerized, and a second layer of adhesive was placed but not polymerized. The soft amalgam was packed into the unpolymerized adhesive, (c) The carved amalgam restoration, (d) Preoperative radiograph. (e ) Postoperative radiograph. (Courtesy of Dr John Khademi, Durango, Colorado.)

6. Unlike a resin buildup, the author cements a metal post as a separate step. Use your preferred method to cement the post. This can be accomplished with zinc phosphate cement, glass-ionomer cement, a selfadhesive resin cement, or by following the procedures previously described for fiber posts. 7. Place a matrix (Fig 24-6a). Matrices are described in detail in chapter 23. 8. Apply a reducing agent such as 10% sodium ascorbate to the dentin surfaces. This will reverse the oxidizing effects of the sodium hypochlorite and provide a stronger bond to the dentin. 9. Acid etch the enamel (if present) with 37% phosphoric acid with agitation for 30 seconds and the dentin for 15 seconds, and then rinse and air-dry. 10. Apply 2% chlorhexidine to the dentin, allow it to soak for 30 seconds, and air-dry until the surface is moist with no pooling. 11. Apply the primer from a dual-curing adhesive system to all the dentin surfaces for about 20 seconds and thoroughly air-dry. 12. Mix and apply a thin layer of dual-curing adhesive to the dentin and light polymerize. 13. Inject the dual-curing build-up material into the canal just short of the orifice, and seat the post. Remove the excess resin and light polymerize (Fig 24-6b). 14. Apply a second layer of dual-curing adhesive to the remaining dentin surfaces, but do not polymerize. 15. Pack amalgam into the matrix unset resin. 16. Slightly overfill the cavity preparation and matrix with a fast-setting amalgam. Allow the amalgam to set for 10 to 15 minutes. 17. Carefully remove the matrix, and trim and shape the buildup (Fig 24-6c). In some cases, the author roughpreps the tooth at this point with a fine diamond bur.

Metal Posts and Silver Amalgam Buildups Silver amalgam is often the material of choice in the posterior region for large buildups or for teeth with subgingival margins. Amalgam provides strength and rigidity for large buildups, and for deep subgingival margins, where isolation is difficult, amalgam is less sensitive to fluid contamination than composite materials (see chapter 23). In most cases, it is desirable to use a self -curing or dualcuring dentin adhesive with amalgam buildups because they strengthen the tooth, at least in the short term. The author only uses metal posts with amalgam buildups, because there is no effective way to join the amalgam buildup to a fiber post. The author's procedural routine for a bonded amalgam buildup is as follows: 1. Grossly clean the canal with a twist drill that corresponds to the taper of the canal preparation. Little, if any, dentin should be removed in this process. 2. The remaining remnants of gutta -percha, sealer, and temporary filling materials can be removed with rotary brushes in a low -speed handpiece and/or with microbrushes dipped in alcohol or a detergent. Air abrasion is an effective way to clean the pulpal floor. 3. Inspect the dentin under the microscope to make sure that the canal walls are clean and pristine. 4. Select a post. Because the vast majority of prefabricated metal posts are parallel, while the canals are tapered, the author adjusts one end of the post for taper until it fits passively into the canal space. The other end is reduced in length to allow it to be covered by about 2 mm of buildup material. Confirm the fit with a radiograph if necessary. 5. Abrade the post surface with a bur and then air abrade with 50-micron alumina particles. Clean the post in an ultrasonic cleaner or by hand.

Preoperative and postoperative radiographs are shown in Figs 24-6d and 24-6e, respectively.

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References

Fig 24-7 (a) The dentin surface was scrubbed with alcohol, but a film remained on the dentin, (b) Air abrasion with 50-micron aluminum oxide provided a clean surface for bonding. (Courtesy of Dr Fred Tsutsui, Torrence, California.)

Fig 24- 8 (a and b) Decay removal extended almost to the alveolar bone in one area of the tooth. It was decided to restore the tooth with silver amalgam and place the finish line for the crown on the amalgam. This made it much easier to get a good impression, make a crown that fit, and remove the excess cement. (Courtesy of Dr John Khademi, Durango, Colorado.)

Clinical Tips

3. Balto K. Root filled teeth with adequate restorations and root canal treatment have better outcomes. Evid Based Dent 2011;12:72-73. 4. Willershausen B, Tekyatan H, Krummenauer F Briseno Marroquin B. Survival rate of endodontically treated teeth in relation to conservative vs post insertion techniques: A retrospective study. Eur J Med Res 2005;20:204-208. 5. Schmitter M, Huy C, Ohlmann B, Gabbert O, Gilde H, Rammelsberg R Fracture resistance of upper and lower incisors restored with glass fiber reinforced posts. J Endod 2006;32: 328-330. 6. Rosentritt M, Sikora M, Behr M, Handel G. In vitro fracture resistance and marginal adaptation of metallic and toothcoloured post systems. J Oral Rehabil 2004;31:675-681. 7. Salameh Z, Sorrentino R, Ounsi HF, et al. Effect of different all-ceramic crown system on fracture resistance and failure pattern of endodontically treated maxillary premolars restored with and without glass fiber posts. J Endod 2007; 33:848-851. 8. Bitter K, Meyer-Lueckel H, Fotiadis N, et al. Influence of endodontic treatment, post insertion, and ceramic restoration on the fracture resistance of maxillary premolars. Int Endod J 2010;43:469-477. 9. Schmoldt SJ, Kirkpatrick TC, Rutledge RE, Yaccino JM. Reinforcement of simulated immature roots restored with composite resin, mineral trioxide aggregate, gutta-percha, or a fiber post after thermocycling. J Endod 2011;37:1390-1393. 10. Tanalp J, Dikbas I, Malkondu O, Ersev H, Gungor T, Bayirli G. Comparison of the fracture resistance of simulated imma ture permanent teeth using various canal filling materials and fiber posts. Dent Traumatol 2012;28:457-464. 11. Cauwels RG, Lassila LV, Martens LC, Vallittu PK, Verbeeck RM. Fracture resistance of endodontically restored, weakened incisors. Dent Traumatol 2014;30:348-355. 12. Brito-Junior M, Pereira RD, Verissimo C, et al. Fracture resistance and stress distribution of simulated immature teeth after apexification with mineral trioxide aggregate. Int Endod J 2014;47:958-966. 13. Dikbas I, Tanalp J, Koksal T, Yalmz A, Gungor T. Investigation of the effect of different prefabricated intracanal posts on fracture resistance of simulated immature teeth. Dent Traumatol 2014;30:49-54. 14. Tjaderhane L, Nascimento FD, Breschi L, et al. Strategies to prevent hydrolytic degradation of the hybrid layer: A review. Dent Mater 2013;29:999-1011.

•Optimal bonding requires clean dentin. Air abrasion is

;

an effective method to clean the chamber. Scrubbing the dentin with alcohol or other solvents leaves behind a film (Fig 24-7 a). Air abrasion with aluminum oxide removes the film and provides an optimal surface for bonding (Fig 24-7b). •The author tries to use as few different materials as possible. Consequently, he uses the same materials and methods to cement metal posts as fiber posts. This makes sense from an expense standpoint and also

limits the number of different procedures the doctor and assistant need to remember. •For bonded amalgam buildups, a self-curing adhesive system such as Amalgambond (Parkell) can be used. The author places dual-curing adhesive in two layers, the first polymerized and the second unpolymerized. This once again limits the number of products in the office. •When a deep subgingival margin is present in one area, the author occasionally places that section of the finish line on the amalgam. The rest of the finish line is placed on tooth structure. Consider this approach in situations where crown lengthening would result in an exposed furcation or require excessive bone removal (Fig 24- 8).

References 1. Ray HA, Trope M. Periapical status of endodontically treated

teeth in relation to the technical quality of the root filling and the coronal restoration. Int Endod J 1995;28:12-18. 2. Tavares PB, Bonte E, Boukpessi T, Siqueira JF Jr, Lasfargues JJ. Prevalence of apical periodontitis in root canal-treated teeth from an urban French population: Influence of the quality of root canal fillings and coronal restorations. J Endod 2009;35:810-813.

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CHAPTER

Ron Fransman, DDS

Esthetic Restoration of

Modern restorative materials make it possible to restore an endodontic access cavity with excellent function and esthetics. Molars and premolars are often visible during speaking and smiling, so producing a nice esthetic result can be challenging. This is particular ly true for metal-ceramic restorations. Most of the composite resins on the market are made to mimic the transparency and translucency of natural tooth structure, whereas metal-ceramic crowns tend to be more opaque. Access restorations with standard composites are usually too transluce nt and low in value, thus creating a restoration that looks gray (Fig 25 -1). Opaque composites can be used to mask the metal and to create a higher value, but this tends to make the restoration look opaque and unnatural (Fig 25 - 2). This chapter describes how to restore an access cavity in a metalceramic crown without the use of metal opaques. See chapter 26 for more detail on composite bonding to ceramic materials.

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Clinical Technique

Fig 25-1 Most composite resins are designed Fig 25-2 (a and b) An example of an access cavity restored using opaque composite to mimic tooth structure but look gray and trans- to mask the metal. Note how the result looks opaque and unnatural, lucent when used to restore the access cavity of a metal-ceramic crown.

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.

Recommended Reading

Composite- ceramic hybrids Like zirconia, this class of materials does not etch. The bonding procedure is as follows:

Alex G. Preparing porcelain surfaces for optimal bonding. Compend Contin Educ Dent 2008;29:324-335. Conrad HJ, Seong W, Pesun IJ. Current ceramic materials and systems with clinical recommendations: A systematic review. J Prosthet Dent 2007;98:389-404. Donovan TE. Factors essential for successful all-ceramic restorations. J Am Dent Assoc 2008;139(suppl):14 S—18 S. Giordano R, McLaren EA. Ceramics overview: Classification by microstructure and processing methods. Compend Contin Educ Dent 2010;31 :682-684. Griggs JA . Recent advances in materials for all-ceramic restorations . Dent Clin North Am 2007;51:713-727.

1. Clean and roughen the surface of the restoration. 2. Etch the dentin with 37% phosphoric acid for 15 seconds, and then rinse and air-dry. 3. Apply dentin primer to the dentin and air- dry. 4. Apply adhesive to all surfaces and light cure. 5. Place the composite and polymerize.

Clinical Tips •Chairside air abrasion is a good method for cleaning and roughening ceramics in preparation for bonding. The same applies to dentin. Several companies sell chairside microetchers that connect to an air source or the air- water syringe. •Companies that sell ceramic primers are starting to develop cleaning agents that clean the ceramic surface and remove salivary contaminants for optimal bonding. One example is Ivoclean (Ivoclar), which is used with Monobond Plus.

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PART VI

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CHAPTER

Richard Schwartz, DDS &

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Diagnosis and Treatment Planning for Resorotion

Root resorption and apposition is a constant physiologic process in a normal dentition, resulting in little change in the root mass. Pathologic resorption, on the other hand, causes a progressive loss of tooth structure. It occurs when there is a break in the protective covering of the dentin, the cementum on the external surface, or the odontoblast layer on the internal surface, which allows clastic cells from the circulatory system access to the dentin. Resorption is frequently diagnosed too late for effective treatment; misdiagnosed; or treated inappropriately, even in the endodontic and periodontal communities Resorption is described in the dental literature by a variety of names and categories. For the purposes of this chapter, pathologic resorption will be categorized into four basic types—one internal and three external:

.

•Internal resorption (IR) •Invasive cervical resorption (ICR) •External inflammatory resorption (EIR) •Replacement resorption (RR) Most teeth with resorption that are referred to the author's endodontic practice are incorrectly diagnosed as IR. In fact, IR is fairly uncommon. While preparing a journal article in 2010, the author found that the dental literature did not provide prevalence figures for resorption, so he searched his practice's 2009 patient database ( with two endodontists) for the incidence of resorption. Of approximately 3,000 patient evaluations, 67 cases of resorption were diagnosed in the following

proportions:

•IR: 3 cases •ICR: 49 cases •EIR: 11 cases •RR: 4 cases

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Diagnosis and Treatment Planning for Rosorption Tablt 27-1

Characteristics of pathologic rosorption Pulpal status

Symptoms

Location

Internal resorption

Vital or nonvital

Usually asymptomatic

Invasive cervical rosorption

Usually vital

Usually asymptomatic

External inflammatory resorption

Nocrotic

Usually asymptomatic

Replacement resorption

Necrotic

Usually asymptomatic

Centered around the canal Anywhere on the root but usually in the cervical area " Moth-eaten " edges of the root in any location Any location on the root

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Fig 27- 1 IR lesions are usually round or oval - shaped and centered on tho root canal, and tho canal is not evident through the lesion.

Fig 27- 2 IR is sometimes seen in Fig 27- 3 (a and b ) IR can progress rapidly. These radiographs were taken primary teeth. (Courtesy of Dr Ven - 4 years apart. (Courtesy of Dr Mitchell Davich, Morristown, New Jersey.) kat Canakapalli, Auckland, New Zealand.)

ly uncommon. As previously mentioned, the author ' s practice identified only 3 cases out of 3,000 patients in 2009, an incidence of only 0.1%. IR originates in a vital pulp, and the pulp must remain vital for the resorption to be progressive. In many cases, IR is discovered af ter the pulp has become necrotic and the process has arrested. The etiology of IR is uncertain, but initiation of IR is thought to occur from a disruption of the odontoblast layer, allowing clastic cells direct contact with dentin. Teeth with IR are usually asymptomatic and are often identified radiographically (Fig 27 -1). They are sometimes identified clinically when resorption is in the coronal area and the tooth takes on a pink hue. IR can occur in permanent or primary teeth (Fig 27- 2) and can progress fairly rapidly (Fig 27- 3). Radiographically, IR is usually round or oval-shaped and centered on the root canal, and the canal is not visible through the resorption (see Fig 27- 1). Whereas with external resorption the canal and resorptive defect are superimposed on the radiograph so that the canal is usually visible, with IR the defect is a widening of the canal.

Based on these numbers, the proper diagnosis for the vast majority of teeth referred with resorption is ICR . Making the proper diagnosis is critical, because the prognosis and treatment protocols vary greatly depending on the type of resorption. The occurrence of EIR and RR in a practice depends on the age of the patient population, because these types of resorption occur primarily in children and adolescents. In 2012, the author searched his database from 2011 and found that he had diagnosed 42 cases of ICR by himself. This seems to support the common belief that the prevalence of ICR is increasing.

This chapter reviews diagnosis of and treatment planning for the four pathologic forms of resorption. Table 27 - 1 summarizes the basic characteristics of each form of pathologic resorption

.

Internal Resorption Diagnosis Of the four types of pathologic resorption, IR is the best known in the dental community, even though it is fair-

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Invasive Cervical Resorption

Fig 27- 4 (a to c) CT imaging shows the precise location and size of IR and whether the lesion perforates the root.

Fig 27- 5 (a and b ) Radiographically, ICR can be quite obvious or barely detectable.

Invasive Cervical Resorption

Treatment planning When IR is diagnosed, there are generally three treatment options:

Diagnosis

1. No treatment with eventual extraction if and when the tooth becomes symptomatic 2. Immediate extraction 3. Internal treatment including conventional root canal

ICR invades the tooth through small penetration points from the periodontal ligament (PDL), apical to the epithelial attachment. It is not clinically evident until it becomes quite large because the external surface of the crown remains intact, the pulp remains vital, and the tooth remains asymptomatic throughout most of the process. In most cases, ICR is first detected radiographically. When the resorptive lesion becomes quite large, the tooth may take on a pink appearance due to granulation tissue showing through the thinned tooth struc ture. The thin external surface of the tooth may break down late in the process. On periapical radiographs, ICR may be a barely discernable radiolucency or it may be dramatically evident. The lesions vary from well- delineated radiolucencies that are quite obvious (Fig 27-5 a) to poorly defined lesions with irregular borders (Fig 27-5b), and they sometimes resemble caries radiographically (Fig 27-6). ICR is often seen in the cervical area of the tooth, but because it is initiated apical to the epithelial attachment, it can present

treatment

IR that is contained within the root with no perforations has a good prognosis for treatment with conventional endodontic treatment. If the resorption perforates the root, the prognosis for treatment is somewhat reduced. If the resorption is in the cervical area of the tooth, the long-term viability of the tooth needs to be considered from a structural standpoint, particularly for anterior teeth. Perforating resorption can sometimes be repaired successfully with mineral trioxide aggregate. Treatment of IR is discussed in detail in chapters 28 and 29. Computed tomography (CT) imaging can be very useful with IR in determining the location and extent of the resorption and whether it perforates the root (Fig 27 -4).

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Diagnosis and Treatment Planning for Resorption

Fig 27- 6 The radiographic appearance of ICR can look somewhat similar to decay.

Fig 27-7 The outline of the root canal can usually be seen through the resorptive lesion with ICR .

Fig 27- 8 An example of ICR in a tooth that was referred with the provisional diagnosis of IR . (Courtesy of Dr Tim Silbert, Perth, Australia.)

Fig 27- 9 (a to d ) ICR is sometimes small and very hard to detect without CT imaging (b and d ). It is not always in the cervical area.

Fig 27-10 (a to d ) ICR can be very destructive. (Courtesy of Dr Marga Ree, Purmerend, The Netherlands.)

anywhere in the root. When ICR is superimposed on the pulp radiographically, the pulp space anatomy is usually evident (Fig 27-7). Because most of the resorption occurs inside the tooth, ICR is often misdiagnosed as IR (Fig 27 -8). The clinician needs to look closely for the outline of the canal or pulp chamber to help make the distinction. Angled radiographs and CT imaging are also helpful. ICR sometimes occurs in only one location, but it is not unusual for it to occur in multiple teeth. Once identified, it is important to carefully examine a full-mouth series of radiographs to identify any other occurrences. If identified early when the lesion is small (Fig 27-9), it may be easy to treat with a small restoration without the need for endodontic treatment. On the other hand, it can become very destructive (Fig 27-10). It is not a good idea to tell

the patient that you will just "watch it," unless the tooth is untreatable and the plan is for extraction at a later time. A common finding in the larger lesions is fingerlike projec tions from the main body of resorption that extend apically and out to the PDL (Fig 27 -11), which make it very difficult to eliminate all the invading resorptive tissue. ICR is sometimes mistaken for caries because they look somewhat similar radiographically (see Fig 27-6). However, a closer look reveals the " layered" look of ICR and the fact that it tracks the canal space apically. The author sometimes receives calls from dentists who are confused because when they entered a tooth they thought was affected by caries, there was bleeding or even hemorrhaging, despite the fact that they were not close to the pulp.

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Invasive Cervical Resorption

b Fig 27-11 fa and b) Multiple penetration points and tracts are shown clinically and radiographically. (c and d ) ICR tracts are shown internally in an extracted tooth. (Parts a to d courtesy of Dr Gary Carr, San Diego, California.) (e) An extracted tooth with ICR showing multiple communications with the PDL. This is one reason why Class 3 and Class 4 ICR are so hard to treat successfully.

Fig 27-12 fa) Most ICR lesions are hemorrhagic on entry, (b ) A smaller percentage of ICR lesions are dry and leathery on entry. Note the dark spots, which represent tracts. (Parts a and b courtesy of Dr Marga Ree, Purmerend, The Netherlands.) (c) A small percentage of the time, ICR lesions look like bone. (Courtesy of Dr Michael Trudeau, Suffolk, Virginia.)

When an intact tooth with ICR is entered, the resorptive tissue is usually hemorrhagic and soft (Fig 27-12a). When the external tooth surface has broken down, ICR often

Fig 27-13 Bone is a common histologic finding in ICR lesions, (Courtesy of Dr Gary Carr, San Diego, California.)

Heithersay wrote a classic series of articles in which he described the features, possible predisposing factors, and recommended treatment regimen for ICR. His treatment regimen included mechanical and chemical debridement of the resorptive lesions followed by restoration. For small, localized lesions (Class 1 or 2), he reported successful treatment of close to 100%. For moderate-size lesions (Class 3), he reported 77.8% success. And for extensive, Class 4 lesions, his success rate was only 12.5% (Fig 27-14).

dry, leathery lesion with a honeycombed appearance under magnification, which looks somewhat like caries. Close examination reveals dark spots, which represent the resorptive tracts (Fig 27 -12b). Removal of the leathery material usually results in bleeding spots as you approach the external surface of the tooth. Occasionally, ICR looks like bone that has invaded the tooth (Fig 27-12c). Histologically, bone is often present (Fig 27-13).

presents as a

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Diagnosis and Treatment Planning for Resorption

Fig 27-14 The Heithersay classification of ICR.

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Fig 27-15 (a to c/J Small ICR lesions can sometimes be treated without prior endodontic treatment.

Treatment planning When ICR is diagnosed, there are generally five ment options:

external surface of the tooth remains grossly intact. See chapter 28 for a more detailed discussion of nonsurgical treatment of ICR. Unless the lesion is very small, treatment option 4 of ten requires endodontic treatment at a later time, so the author generally performs endodontic treatment before treating the resorption. However, with smaller lesions it is sometimes possible to treat the ICR without any endodontic treatment (Fig 27 -15). Orthodontic extrusion may be helpful in treating some patients with ICR who have sufficiently long roots. Extrusion provides better access to ICR lesions and allows the final bony and gingival architecture to be more ideal when surgery is necessary.

treat-

1. No treatment, with eventual extraction if and when the tooth becomes symptomatic 2. Immediate extraction 3. Internal treatment, including root canal treatment 4. Surgical treatment, without root canal treatment (Class 1 or sometimes Class 2 lesions) 5. Surgical treatment, in combination with root canal treatment and internal debridement

Dental implants have led to increasing use of treatand 2. The author generally recommends option 1 or 2 for Class 3 and especially for Class 4 lesions. Also, location and esthetic concerns may dictate which option is selected. If treatment is planned for medium to large resorptive lesions, purely internal treatment of ICR (option 3) is preferable when possible. There is the obvious desire of most patients to avoid surgery, plus the fact that surgical treatment usually requires bone removal and may result in bone removal from adjacent teeth and a significant periodontal defect in the area of the resorption. Although it is impossible to completely eliminate the resorption from inside the tooth, careful mechanical and chemical debridement can stop the resorptive process and result in long-term success. This approach is viable only if the

ment options 1

External Inflammatory Resorption Diagnosis EIR usually occurs following trauma, and pulpal necro sis and intraradicular infection must be present. It is thought that a break in the cementum allows clastic cells to initiate dentin resorption, which continues as it is stimulated by the necrotic, infected pulp. Clinically, teeth with EIR look normal, but the adjacent gingiva is often red and inflamed, and occasional-

[250]

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Replacement Resorption Fig 27-16 EIR has a typical “motheaten" look with small “bites" out of the edges of the root.

Fig 27-17 (a and b) EIR can progress rapidly and be very destructive. It should be treated immediately upon diagnosis. These radiographs were taken only 8 months apart.

Distolabial surface

Fig 27-18 (a to d ) CT imaging can be very helpful in early detection of EIR . The resorption tends to be more obvious than in periapical radiographs, plus the tooth can be viewed in three dimensions. (Courtesy of Dr Fred Barnett, Philadelphia, Pennsylvania.)

ly there is a sinus tract present. A tooth with EIR has a typical “ moth- eaten " radiographic appearance, with irregular borders, little "bites" out of the edges, and adjacent radiolucent areas in the bone (Fig 27 -16) . EIR can be initiated in a matter of weeks af ter a traumatic event and can progress rapidly (Fig 27 -17 ). CT imaging can be helpful in making an early diagnosis when the changes are subtle (Fig 27 -18).

Replacement Resorption Diagnosis Like EIR, RR occurs most commonly after a traumatic event. The PDL may be damaged by crushing or tearing or may dry out in cases of avulsion. Root dentin is

resorbed and replaced by bone, and ankylosis occurs in the areas where there is no PDL. Clinically, an ankylosed tooth appears to be " shorter" over time, as the other teeth passively erupt. It emits a dull sound when percussed, which is noticeably different from the higher-pitched "ringing" sound of a tooth with an intact PDL. The onset of clinical signs of RR usually takes several months, and it tends to progress more slowly than EIR. Radiographically, the PDL disappears and the outline of the root becomes indistinct (Fig 27-19).

Treatment planning When EIR is diagnosed, there are generally three treatment options:

1. No treatment, with eventual extraction if and when the tooth becomes symptomatic 2. Immediate extraction 3. Root canal treatment It is important to start treatment as soon as possible once EIR is diagnosed. The author plans for a 3 - to 6-month treatment period for cases of EIR. See chapter 30 for a more detailed discussion of treatment of EIR.

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Diagnosis and Treatment Planning for Resorption

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Fig 27- 20 (a to d ) CT imaging sometimes identifies resorption that is otherwise not detectable on a periapical radiograph. In this case, the treatment plan was completely changed because of the additional information provided by the CT images. (Courtesy of Dr Alana Keough, Vero Beach, Florida.)

Treatment planning

may eventually fail due to fracture even though the endodontic treatment is successful. The endodontic treatment is irrelevant if the resorption is not eliminated and the restorative aspects are not managed properly.

There is no known treatment to arrest RR, and it may progress to the point that the crown snaps off. It is some times managed by root submergence (see chapter 31).

Recommended Reading

CT Imaging

Bakland LK, Andreasen JO. Will mineral trioxide aggregate replace calcium hydroxide in treating pulpal and periodontal healing complications subsequent to dental trauma ? A review. Dent Traumatol 2012;28:25-32. Heithersay GS. Invasive cervical resorption. Endod Top 2004; 7:73-92. Patel S, Kanagasingam S, Pitt Ford T. External cervical resorp tion: A review. J Endod 2009;35:616-625. Patel S, Ricucci D, Durak C, Tay F. Internal root resorption: A review. J Endod 2010;36:1107-1121. Schwartz RS, Robbins JW, Rindler E. Management of invasive cervical resorption: Observations from three private practices and a report of three cases. J Endod 2010;36:1721-1730.

The increasing use of CT imaging in endodontics has been very helpful in the diagnosis of and treatment planning for resorption. CT imaging can identify resorption that is not evident on periapical radiographs (Fig 27-20). It precisely locates the lesions in three dimensions and provides a more accurate estimation of size compared with periapical radiographs. In some cases, it may discourage treatment. CT images also provide information about the relationship of the lesion to the surrounding bone, which can be very helpful in decision-making.

Conclusion It is important to understand the periodontal and restorative aspects of treating pathologic resorption. Teeth with resorption are often structurally compromised and

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CHAPTER

Richard Schwartz, DDS

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Nonsurgical Treatment of Invasive Cervical Resorption

The recommended treatment for Heithersay Class 3 and Class 4 resorptive lesions (see chapter 27) is often immediate or eventual extraction, but some may be treated with an internal approach (no surgery) if the conditions are favorable and the patient is so inclined. Favorable conditions include the following:

•The resorption must be accessible without excessive removal of cervical and radicular dentin. •The tooth must have adequate remaining structural integrity once the resorption is removed for a reasonable prognosis. The • external root surface must be radiographically intact on computed tomography (CT) images. •The patient must be "on board " with the treatment and the guarded prognosis.

A surgical approach is often not practical if the resorption extends apical to the alveolar crest. If bone removal is necessary for external access to the resorption (see Fig 28-1), the result is often bone removal from adjacent teeth as well as a periodontal defect adjacent to the tooth with the resorption. The internal approach utilizes chemomechanical debridement to remove as much of the resorption as possible through the endodontic access, using a round bur in combination with 90% aqueous trichloroacetic acid (TCA), calcium hydroxide (Ca[ OH ]2), and sodium hypochlorite. Because the resorption originates in the periodontal ligament, it is impossible to totally eliminate it without perfo rating the external surface of the root, so we must rely on the TCA to cauterize any active resorptive tissue that remains. If any of the invading resorptive tissue remains viable, the resorptive process is likely to continue. The TCA chemically debrides the resorptive tissue and makes the remaining resorption stand out from the normal dentin, which aids in identification and removal. After application of TCA, the resorption will look whiter, more irregular, and somewhat layered when viewed with magnification. The tracts and penetration points will look dark (see Fig 27-12).

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Nonsurgical Treatment of Invasive Cervical Resorption

Clinical Procedure

Clinical Cases

The author uses a slightly modified version of the Heithersay approach to debride the resorptive lesion, which usually takes several appointments to complete.

Case 28-1

First appointment 1. Make access, locate the canal(s), and do an initial pulpectomy. In most cases, there will be bleeding from the resorption and sometimes hemorrhage. 2. If there is hemorrhage, gently debride the invasive cervical resorption (ICR) with a round bur in a lowspeed handpiece. 3. Place TCA on a cotton pellet and scrub the internal surfaces several times until the bleeding has slowed or stopped. Debride further with a bur, which may uncover new bleeding points, and reapply the TCA. 4. Once the bleeding is under control, establish the working length and clean and shape the canal(s). 5. Place Ca (OH)2 in the canals and resorptive area. 6. Schedule another appointment in 2 to 4 weeks.

Intermediate appointments There should be no bleeding upon re -entry. 1. Remove the Ca(OH)2, confirm the working length, and complete instrumentation of the canal(s) if necessary. 2. Further debride the resorptive areas with a bur and TCA. New bleeding points may emerge as the resorption is removed. 3. Repeat this process until nearly all of the resorption has been eliminated and perforation is imminent. This may take an additional appointment or two. 4. Place Ca (OH) 2 in the canals and resorptive lesion at

the end of each appointment. 5. Treatment is completed when the Ca(OH)2 fills the entire radiolucent resorptive defect on radiographs.

Final appointment 1. Treat the area where the dark penetration points remain with TCA. 2. Lightly "refresh" the dentin surfaces with a bur to pro-

vide a suitable surface for bonding. 3. Complete root canal treatment and restore the tooth with bonded composite and a fiber post or two if it is an anterior tooth or premolar (see chapter 24).

A 47-year-old man was referred to the author's endodontic practice in 2002 with no symptoms, but the pulp chamber of

the maxillary right second molar had an unusual radiographic appearance (Fig 28-1a). The external surface of the tooth was intact. The referring doctor's tentative diagnosis was internal resorption. The tooth was nontender to pressure and percussion and responded normally to cold compared with his other teeth. There were no significant periodontal pockets. The endodontic diagnosis was normal pulp and normal periapex. The radiolucent lesion was diagnosed as ICR. The patient was presented with three options: ( 1 ) no treatment with eventual extraction of the tooth when it became symptomatic, (2) extraction now, or (3 ) endodontic treatment followed by internal debridement and restoration. Because of the need for excessive bone removal with a surgical approach, this was not considered. The patient opted for option no. 3. Occlusal access was made, and there was immediate hemorrhage. Gross debridement was accomplished with a no. 6 round carbide bur in a low-speed handpiece, and the hemorrhage decreased. Debridement of the lesion was accomplished by alternating the round bur with TCA. Numerous small bleeding points were evident in the cervical area after initial debridement Once the dentin was treated with TCA, the bleeding stopped and there were small dark spots representing resorptive tracts that could be seen clearly under the operating microscope. The initial debridement caused the pulp to be ex posed, and endodontic treatment was initiated. Four canals were located and prepared, and Ca (OH)2 was placed in the canals and resorptive lesion. At the second appointment, additional debridement was accomplished as previously described, until the author felt that a perforation was imminent. The deep dentin was given a final "scrub " with TCA. The canals were obturated, the dentin surface was " refreshed" with a bur, and the lesion and access opening were restored with bonded composite resin (Fig 28-1b). The tooth was later restored with a crown. The radiographs in Figs 28-1c and 28-1d show the recalls at 8 and 11 years, respectively. The patient's tooth was asymptomatic and functional, and there was no evidence that the ICR had progressed.

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Clinical Cases

Fig 28-1 (a ) The patient was referred for treatment of internal resorption because of the unusual appearance of the pulp chamber. It was diagnosed as invasive cervical resorption (ICR), which was amenable to internal treatment . Consider how much bone removal would have been required from the distal aspect of the tooth to treat it surgically, (b ) Endodontic treatment was completed, and the resorptive lesion was debrided chemomechanically and restored with composite. The tooth was restored with a crown shortly after treatment was complete, (c) Eight -year recall, (d ) Eleven-year recall. The tooth is stable and functional, and there is no evidence that the resorption has recurred.

control. Ca(OH)2 paste was placed in the canal and partially filled the resorptive defect (Fig 28-2f). At the second appointment, the patient was asymptomatic and the resorption was not bleeding. It was further debrided with a bur and TCA which uncovered some new bleeding points. Ca (OH) 2 was placed again, filling more of the resorptive lesion (Fig 28- 2g). This process was repeated at the third appointment, and the final radiograph showed that the Ca (OH) 2 appeared to fill almost the entire resorptive lesion (Fig 28-2h). The Ca(OH) 2 was changed one more time (Fig 28-2i). At the fifth appointment, the apical portion of the canal was obturated (Fig 28- 2j), the internal dentin was refreshed with a bur, and the tooth was restored with a fiber post and bonded composite resin (Fig 28- 2k). The 2-year recall radiograph is shown in Fig 28-2I. For teeth with very large ICR lesions, the author uses this staged approach. Over the course of several appointments, the chemomechanical debridement allows the Ca (OH)2 to "expand " and fill the lesion, at which time treatment is completed.

Case 28- 2 A 50-year-old woman presented in 2011 with mild spontaneous pain and tenderness and Class 4 ICR (Fig 28-2a) in the maxillary right central incisor. The tooth had a weak, delayed response to cold compared with the adjacent teeth. Clinically, the tooth had a pink hue, but the external surface of the tooth was intact. Because of the extensive resorption, extraction and an implant were recommended to her as the most predictable treatment approach. However, she opted to retain the tooth if pos-

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sible. A CT scan showed that the external surface of the tooth was radiographically intact (Figs 28-2b to 28 -2d), so internal treatment was possible. Linguo - incisal access was made, causing immediate hemorrhage. The soft areas of the resorption were debrided with a bur, which caused the hemorrhaging to slow down. The root canal was located and instrumented (Fig 28-2e). TCA was applied to the resorptive areas, and they were further debrided with a bur. This process was repeated several times until the bleeding was under

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Nonsurgical Treatment of Invasive Cervical Resorption

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Fig 28 - 2 (a) Preoperative periapical radiograph showing Class 4 ICR. (b to d) The preoperative CT image provided valuable information in decidinq whether treatment was possible, (e) Access was made; the canal was located and instrumented, (f ) After some initial debridement Ca( ) OH was placed. Much of the resorptive tissue remained at this point , (g) At the second appointment, more and the postoperative radiograph showed that the Ca(OH)2 filled more of the resorptive lesion, ( h) chemomechanical debridement was performed After the third appointment, it appeared resorptive tissue was largely gone and the Ca(OH)2 filled most of the space, ( i ) The Ca( that the OH) was changed one more time and radiographica lly aoDeared to fill the entire space previously occupied by the resorption, ( j ) At the fifth appointment , 2the apical portion of the canal was obturated ( ) was restored with a fiber post and composite resin. (I) Two-year recall. ' k The tooth '

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Summary

Clinical Tips

Summary

•Preoperative

In the author's endodontic practice, ICR is frequently encountered and sometimes treated. For the majority of the treated cases, the author uses an internal approach. If the resorption is accessible and the structural integrity of the tooth can be maintained, long-term success is

CT imaging is very helpful in decisionmaking for all types of resorption, including ICR. If possible, obtain a CT image before treatment is begun.

•Take periodic radiographs to avoid perforation.

•Plan on 3 to 5 appointments for very large lesions such as that

demonstrated in case 28-2.

possible.

•Obtain TCA from a compounding pharmacy. Ask for 90% aqueous TCA in gel form.

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CHAPTER

Richard Schwartz, DDS

Surgical Treatment of Invasive Cervical

Invasive cervical resorption (ICR) is a phenomenon that is largely misunderstood and misdiagnosed within the dental community, despite the fact that it seems to show up with increasing frequency. The resorptive process starts in the periodontal ligament, penetrates microscopically into the root dentin, and can expand in any and all directions. It is frequently misdiagnosed as internal resorption because of its radiographic appearance and the fact that it is not often detectabl e clinically. In most cases, it is first detected radiographically after it has become quite large Early diagnosis is crucial if treatment is necessary. Depending on the location and extent of the resorption and whether the external surface of the tooth is intact, ICR can sometimes be treated nonsurgically (see chapter 29). This treatment is preferable because the surgical approach often requires bone removal and may result in a periodontal defect after healing is complete. However, if cavitation of the external root surface has occurred and the cavitated area is accessible, surgical treatment may be a good option. Depending on the size of the resorption, root canal treatment may or may not be necessary. This chapter describes the treatment of small (Heithersay Class 2) and medium ( Class 3) resorptive lesions that were treated surgically in combination with root canal treatment.

.

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Clinical Cases

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Fig 29-1 (a ) Preoperative radiograph showing cervical resorption on the mandibular left lateral incisor, (b) Endodontic treatment was completed in two visits, (c) The clinical view prior to surgery, (d) A flap was reflected, and the resorption was seen in an accessible location, (e) Rubber dam was placed, and the resorption was debrided with a round bur in combination with three 1-minute scrubs with TCA. ( f ) The cavity was restored with a flowable composite, ( g ) Radiographic appearance at the completion of treatment , ( h ) Eight -year recall.

Clinical Technique

Clinical Cases

If root canal treatment is necessary, perform it first in conjunction with internal debridement of the resorption with a bur and trichloroacetic acid (TCA) (see chapter 28). The surgical protocol is as follows:

Case 29-1 An asymptomatic 39-year-old woman was referred to the author's practice in 2005 with a moderate-size oval radiolucency that was evident on radiographs in the cervical area of the mandibular left lateral incisor (Fig 29-1a). There was a pink discoloration on the labial surface of the tooth and a "catch " in the subgingival area with an explorer. The tentative referral diagnosis was internal resorption. The patient had a history of orthodontic treatment as a teenager and could not recall a history of trauma or any of the other possible predisposing factors. She reported that she owned a cat. Clinical tests showed that the tooth was nontender to pressure and percussion and responded normally to cold compared with the adjacent teeth. There were no significant periodontal pockets. The endodontic diagnosis was normal pulp and normal periapex. The radiolucency was diagnosed as ICR. Treatment options were discussed with the patient, including ( 1 ) no treatment with eventual extraction of the tooth when it became symptomatic; (2) immediate extraction; (3 ) surgical exposure of the lesion, debridement, and restoration without endodontics; or (4) surgical exposure, debridement, and restoration preceded by endodontic treatment. After some discussion, the patient decided

1. Reflect a flap to gain access to the resorption lesion. 2. If possible, place rubber dam. 3. Grossly debride the remaining resorption with a bur. 4. Apply TCA, which renders the remaining resorption

whiter than the surrounding dentin and makes the small penetration tracts turn dark. 5. Remove the remaining resorption and tracts. Bone removal may be required to completely eliminate the resorption. 6. " Refresh " the dentin surface with a bur in preparation for bonding. 7. Restore the tooth with composite resin or resinmodified glass-ionomer cement. . 8 Irrigate thoroughly, replace the flap, and suture.

on option no. 4.

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Surgical Treatment of Invasive Cervical Resorption

Fig 29- 2 (a ) Preoperative view of ICR in the maxillary right first molar. It was originally mistaken for caries, (b ) Buccal and lingual flaps and interproximal bone removal were necessary to fully debride the resorption, (c) Postoperative radiograph, (d) Twelve-year recall.

Fig 29- 3 Soft tissue after accidental contact with TCA.

Root canal treatment was completed in two appointand the access opening was restored using standard methods (Fig 29-1b). A sulcular incision was made, and a small labial flap was reflected with two vertical releasing incisions to expose the resorption (Figs 29-1c and 29-1d). Because the lesion was coronal to the alveolar bone, it was possible to place rubber dam with a 212 retainer (Fig 29-1e). The resorption was dry, had a honeycomb appearance, and could be peeled off in layers with a spoon excavator. The resorption was debrided with a round diamond bur in a high-speed handpiece followed by a no. 6 carbide round bur in a low-speed handpiece. Once the lesion was debrided to smooth, clean dentin, the cavity was scrubbed with 90% aqueous TCA. Several small dark spots of residual resorptive tissue became evident in the cervical area, which was further debrided and scrubbed until all the spots were eliminated. The dentin surface was then “refreshed" with the round bur in preparation for bonding. A fourth-generation dentin bonding system (Optibond FL, Sybron) was used following the manufacturer's instructions, and the cavity was restored with a flowable composite (Figs 29-1f and 29-1g). The flap was repositioned and sutured. Substantial tooth structure remained after the conservative access preparation and relatively small restoration, so no further restorations were recommended. The 8-year recall is shown in Fig 29-1h.

with amalgam (Fig 29- 2a), but the resorption continued to progress because it was incompletely debrided. Af ter explaining the various treatment options, the pa -

ments,

tient opted for surgical treatment. In this case, it was necessary to reflect buccal and lingual flaps and remove interproximal bone to achieve total removal of the resorption (Fig 29-2b). Figures 29 -2c and 29-2d show the postoperative radiograph and 12- year recall radiograph,

respectively.

Clinical Tips •After the flap is reflected, place a rubber dam whenev-

.

er possible It will maintain isolation for the restorative treatment and keep the surgical site clean during fin-

ishing and polishing of the restoration. trioxide aggregate ( MTA) has been recommended in several case reports as the restorative material of choice because it is biocompatible. The author uses resin-modified glass-ionomer materials or com posite resins because they are stronger, bond to tooth structure, and can be exposed to the oral cavity. There are no known benefits to the use of MTA to restore ICR lesions. •The author uses glass ionomer as the first choice to restore subgingival cavities because of ease of use. If esthetics is an issue, a flowable composite may be preferable. •A compounding pharmacy can provide 90% aqueous TCA (in gel form). However, it is very caustic and must be kept away from the soft tissues (Fig 29-3).

•Mineral

Case 29- 2 This scenario is similar to the previous case, except the resorptive lesion was larger and less accessible and the tooth was tender to pressure and percussion. The resorption was originally mistaken for decay and restored

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Recommended Reading It completely demineralizes the dentin to a great depth, which is a problem for bonding. The internal dentin surface should be " refreshed " with a bur prior to bonding procedures whether you are using glassionomer or composite resin restorative materials.

Summary It is preferable to treat ICR nonsurgically when possible. However, when the external surface of the tooth has broken down and is cavitated, a surgical approach can sometimes be employed. The resorption must be accessible to avoid creation of a periodontal defect and negative effects on the adjacent teeth. Two such cases were presented in this chapter, with medium- to longterm

Recommended Reading Heithersay GS. Invasive cervical resorption. Endod Top 2004; 7:73-92. Patel S, Kanagasingam S, Pitt Ford T. External cervical resorption: A review. J Endod 2009;35:616-625. Schwartz RS, Robbins JW, Rindler E. Management of invasive cervical resorption: Observations from three private practices and a report of three cases. J Endod 2010;36:1721-1730. von Arx T, Schawalder P, Ackermann M, Bosshardt DD. Human and feline invasive cervical resorptions: The missing link?— Presentation of four cases. J Endod 2009;35:904-913.

recalls.

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CHAPTER

Treatment of Richard Schwartz, DDS

Internal Resorption and External Inflammatory

Internal resorption (IR) and external inflammatory resorption ( EIR ) are totally different entities, but their treatment is somewhat similar and generally predictable, so they are grouped together in this chapter. EIR is always associated with a necrotic, infected pulp. That is also usually the case with IR, although sometimes the pulp is vital. For a more complete discussion of diagnosis and treatment planning of these entities, see chapter 27. Treatment of IR and EIR utilizes standard endodontic methods: The canals are shaped, disinfected, and obturated. The author treats these teeth in multiple appointments, using calcium hydroxide (Ca[ OH ]2) as an intermediate dressing. Treatment of EIR usually requires 3 to 6 months and multiple changes of the Ca (OH)2 dressing until the bone is healed and the periodontal ligament (PDL) is intact. Treatment of IR, on the other hand, is frequently completed in two appointments. Treatment of IR is most predictable when no perforations are present, but perforations do not preclude a successful outcome (Fig 30-1). Computed tomography (CT) imaging can be very helpful in making that determination. The goals of treatment for both of these entities are to arrest the resorptive process if it is active, eliminate infection and inflammation, restore the tooth structurally and functionally, and allow regeneration of bone and soft tissue.

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Clinical Procedures

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Fig 30-1 (a ) The patient presented with IR that perforated the apical third, (b ) Access was made; the canal was located apical to the perforation, instrumented, and irrigated, (c) Ca(OH)2 was placed in the canal and extruded out the perforation into the bone, (d ) Most of the canal was obturated with mineral trioxide aggregate (MTA), and the access was restored with a fiber post and composite, (e) Five-year recall. The bone is healed, and the tooth is asymptomatic and functional.

Fig 30- 2 (a to c) Treatment of a typical case of IR. (Courtesy of Dr Jerry Avillion, Ft Smith, Arkansas.)

2. The root canal system and resorptive lesion should be irrigated and agitated vigorously with sodium hypochlorite to debride the uninstrumented areas. 3. Place Ca(OH)2, restore provisionally, and take a radiograph. Note whether the resorptive lesion fills completely with Ca(OH) 2. If so, and the patient is asymptomatic at the second appointment, the tooth is ready to obturate at that time. If not, or if there are still signs of active disease such as an unhealed sinus tract, treatment may require additional appointments. Repeat steps 1 to 3 and schedule another appointment. 4. Obturate when you feel that the canal system and re sorptive lesion are adequately debrided and all signs and symptoms of infection are gone. 5. Restore the tooth immediately or as soon as possible (Fig 30-2).

Clinical Procedures Treatment of nonperforating

internal resorption The clinical protocol for the treatment of nonperforating IR is as follows: 1. Make access, and prepare and disinfect the root canal system. Sometimes it is difficult to locate the canal

beyond the resorptive lesion. Hand files with small bends can usually accomplish this task.

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Treatment of Internal Resorption and External Inflammatory Resorption Fig 30-3 (a) The patient presented with a large, perforating IR defect. (b) Access was made; the canal was prepared and obturated with MTA. Note how some of the material extruded into the bone, (c) Excellent healing was observed at the 11-month recall. (Courtesy of Dr Mark Olesen, Vancouver, Canada.)

Fig 30- 4 (a to c) The author keeps Ca(OH)2 in the canal until the bone is healed.

Treatment of perforating internal resorption

Treatment of external inflammatory resorption

The clinical protocol for the treatment of perforating IR

The clinical protocol for the treatment of EIR is as follows:

is as follows:

1. Make access, prepare and disinfect the root canal system, and place Ca(OH)2. Take a radiograph and note whether the Ca(OH) 2 is completely contained within the tooth or extrudes out the side in any areas. This indicates that the resorption has perforated into the canal space. In the author 's experience, perforations worsen the prognosis for treatment. 2. At 1 month, instrument and irrigate the canal(s) and replace the Ca(OH) 2. In many cases, inflammation of the adjacent soft tissues will be reduced. Recall the patient again at 3 months. 3. At the 3-month appointment, take a radiograph and note whether the bone adjacent to the resorptive lesion has healed and whether the PDL is re-established. If healing is complete, obturate and restore the tooth. If not, replace the Ca(OH) 2 and recall at 5 months. 4. When all evidence of infection is gone and the bone appears to be healed radiographically, treatment is completed and the tooth can be restored (Fig 30- 4).

1. Follow steps 1 to 3 described above. 2. After debridement and disinfection are complete, obturate the canal space apical to the resorptive lesion. This can be done with gutta-percha or mineral trioxide aggregate (MTA). 3. Fill the resorptive lesion with MTA as completely as possible. Indirect ultrasonics is helpful in obtaining a dense fill. Do not be concerned if a small amount of MTA extrudes outside the tooth (Fig 30-3). 4. Obturate and restore the tooth as described above.

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Clinical Cases

Fig 30- 5 {a ) Preoperative radiograph showing IR in the cervical area, (b to d) A CT scan showed that no perforations were present, (e) The canal was prepared and irrigated, and Ca(OH)2 was placed in the canal and resorptive lesion, ( fand g ) At the second appointment, the apical portion of the canal was obturated and the access was restored with a fiber post and composite resin, ( h) Two-year recall.

Clinical Cases

pulp, chronic apical periodontitis, and IR. Because the resorption was extensive and located in the area most susceptible to fracture, extraction was discussed along with root canal treatment and restoration. After some discussion, the patient opted to retain and treat the tooth. Access was made into the necrotic pulp, the canal was instrumented and irrigated with sodium hypochlorite, and Ca(OH)2 was placed in the canal and resorptive area (Fig 30- 5 e). When the patient returned after 1 month, he was asymptomatic. The apical portion of the canal was obturated with gutta-percha and sealer. The remainder of the canal and resorptive lesion were restored with bonded dual- curing composite and a fiber post (Figs 30-5f and 30- 5g). Figure 30-5h shows the 2-year recall radiograph.

Case 30-1: Internal resorption A 64- year-old man presented with tenderness associated with the maxillary left lateral incisor of about 1 week's duration (Fig 30- 5 a). It had been previously restored with a ceramic crown, which was now about 5 years old. There was no other relevant history. Clinical findings included tenderness to pressure and percussion, no response to cold, minimal mobility, and no significant gingival probing depths. Radiographic findings included periapical bone loss and what appeared to be IR in the cervical area. A CT scan showed that it was, in fact, IR that did not perforate (Figs 30- 5b to 30- 5 d). There was extensive destruction in the cervical area, the region of the tooth that is most susceptible to fractures. The maxillary left lateral incisor was diagnosed with a necrotic

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Treatment of Internal Resorption and External Inflammatory Resorption

Case 30-2

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Fig 30- 6 (a to e) The preoperative radiograph shows inflammatory resorption and an open apex. Note the “moth- eaten” appearance of the borders of the root and the adjacent areas of radiolucent bone. The canal was instrumented and irrigated. Ca(OH)2 was placed in the canal and replaced twice over a period of 5 months. Once the bone was healed, the apex was still open, so an apical plug of MTA was placed. The tooth was obturated and restored.

Case 30- 2: External inflammatory

Root canal treatment was initiated, the canal was instrumented and disinfected, and Ca(OH)2 was placed. At 1 month, the swelling was gone, the soft tissues looked pink and healthy, and the patient was asymptomatic. The tooth was re-entered, instrumented, and irrigated, and fresh Ca(OH)2 was placed. This process was repeated at 3 months. At 5 months, a radiograph showed that the bone appeared to be healed and a somewhat irregular PDL was re-established. The adjacent teeth remained vital and showed normal root development. The apex was still somewhat open, so the apical segment was obturated with MTA while the rest of the canal was obturated with gutta-percha and sealer. The access opening was restored with composite.

resorption An 11-year- old boy presented 6 months after getting hit in the mouth by a softball. His maxillary left central incisor had lateral and incisal displacement, but no treatment had been rendered. His mother brought him in for evaluation when he developed gingival swelling. The tooth was nontender, had a mobility of 1, and was nonresponsive to cold. The other incisors were nontender and responded normally to cold. He was diagnosed with a necrotic pulp, chronic apical periodontitis, and EIR (Fig 30-6). The tooth also had an open apex and was positioned more to the incisal than the other central incisor.

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k Summary Fig 30-7 In this case, the EIR was not arrested before the teeth were obturated. For this reason, the author does not obturate until the bone is healed.

Clinical Tip

Summary

The author does not obturate teeth with EIR until the bone is healed in the apical and lateral aspects of the tooth, which usually takes 3 to 6 months. In some cases, earlier obturation fails to arrest the resorptive process

a standard protocol. This chapter described the step-bystep process and presented two clinical cases.

IR and EIR can usually be treated successfully following

(Fig 30-7 ).

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CHAPTER

Flapless Jared Buck, DDS

Decoronation for Teeth with Replacement

Ankylosis and replacement resorption sometimes occur after traumatic injuries to teeth if the periodontal ligament (PDL) is damaged. After the traumatic injury, an inflammatory phase ensues, bone repopulates the damaged root surface instead of PDL, and the root and bone become " fused." This may occur after avulsion or injuries in which the PDL is crushed or torn. Once a tooth is ankylosed, passive eruption ceases, and the tooth gradually looks " shorter " than the surrounding teeth as they continue to erupt (Fig 31-1). There are currently no treatments to prevent, arrest, or reverse replacement resorption; in many cases, it progresses until the tooth is lost due to cervical fracture or other causes. See chapter 27 to read more about differential diagnosis of root resorption. Decoronation is a surgical method for treating ankylosed incisors in children and adolescents. The crown and the root canal contents are removed, leaving the root in situ to be resorbed. The goal of treatment is to preserve the width and height of the alveolus until the patient has completed the rapid growth phase (Figs 31-2 and 31-3), typically the late teens for girls and early 20 s for boys. When teeth are extracted, the alveolus shrinks 40% to 60% in volume during the healing phase, both in height and width. This creates restorative problems for the patient later in life. Decoronation is indicated when there are radiographic and clinical signs of replacement resorption and an incisal edge discrepancy greater than 1 mm according to the guidelines from the International Association of Dental Traumatology.

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Fig 31 -1 When ankylosis occurs, an incisal edge discrepancy develops as the other teeth continue to erupt . (Courtesy of Dr Nishan Odabashian, Glendale, California.)

Fig 31- 2 (a to c) The anterior dentition of an adolescent 1 year after tooth extraction due to trauma. Note the extensive hard and soft tissue loss, which presents restorative difficulties both immediately and in the future. (Courtesy of Dr Benedict Bachstein, Cherry Hill, New Jersey.)

,

Fig 31- 3 Contrast the patient in Fig 31-2 with this patient who underwent decoronation: (a ) immediately postoperative; ( b) at 22 months; and (c) at 30 months. Note how the residual root slowly resorbs and undergoes pulp canal obliteration. The width and height of the alveolar ridge was preserved. (Courtesy of Drs Sharon Sabet, Los Angeles, California, and Michael Trudeau, Suffolk, Virginia.)

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There are four treatment options for ankylosis of an incisor in the developing dentition:

Case Report

1. No treatment: Usually recommended when the incisal edge discrepancy is less than 1 mm 2. Extraction: Carries the risk of catastrophic loss of alve olar bone during tooth removal 3. Orthodontic extrusion: The most common result is intrusion of adjacent teeth and no movement of the

An 8 -year-old boy was hit by the side mirror of a passing car. The maxillary right lateral incisor was laterally luxated, the right central incisor was avulsed, and the left central incisor was subluxated. The avulsed tooth was

placed in milk after 30 minutes of dry time, stored in milk for an hour, and then reimplanted (Fig 31- 4a) and splinted for 10 days. Revascularization was attempted without success (Figs 31- 4b to 31- 4d), followed by calcium hydroxide treatment (Fig 31- 4e). After 9 months, the clinical and radiographic images indicated replacement resorption of the right central incisor (Fig 31- 4f) with an incisal discrepancy greater than 1 mm. A decision was made to proceed with flapless decoronation. A surgical handpiece was used to section and remove the coronal portion of the tooth and reduce it until it was 2 mm below the osseous level (Figs 31-4g to 31- 4k). The contents of the canal were removed (Fig 31 - 41), and a provisional replacement tooth was provided on a " flipper " (Fig 31- 4m). The postoperative period was uneventful. The progression of healing is shown in Figs 31-4n to 31- 4u.

ankylosed tooth 4. Decoronation: Preserves the alveolar height and width "Traditional " decoronation has utilized a full-thickness flap. However, a flapless approach for this procedure provides several advantages: It decreases postoperative pain and is a shorter procedure, which is always beneficial when working with children and adolescents. The flapless technique is described in the case report that follows.

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Flapless Decoronation for Teeth with Replacement Resorption

Fig 31- 4 Revascularization was attempted, unsuccessfully, on this maxillary right central incisor: ( a and b) preoperative radiographs; (c) at 2 weeks; (d ) at 2 months; (e) at 3 months; (f ) at 9 months. (Courtesy of Dr David Prusakowski, Boca Raton, Florida.) ( g and h ) The crown was sectioned, and the pieces were removed from the root slightly coronal to the gingival margin, ( i to k ) The remaining shell of the crown was reduced with a round bur and high- speed handpiece in combination with a curette.

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Case Report

Case 31-1 (cont )

Fig 31-4 (cont ) (I) The tooth should be reduced 2 mm apical to the alveolar crest. The pulp or obturating materials were removed from the canal, ( m ) A removable appliance provides temporary tooth replacement in most cases, ( n and o ) Preoperative clinical and radiographic views of the tooth, (p and q ) Postoperative clinical and radiographic views, (r ) One- week recall, fs to u ) Clinical and radiographic views at 5 months. Note how the root was resorbing.

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Flapless Decoronation for Teeth with Replacement Resorption

Summary

Recommended Reading

Flapless decoronation provides a fairly simple method alveolar architecture for future prosthodontic replacement of the missing tooth once the patient's growth has stabilized. In most cases, there is little postoperative pain or swelling. Obtaining a satisfactory restorative result can be very difficult without adequate volume of the alveolar ridge.

Andersson L, Andreasen JO, Day P, et al. International Associa tion of Dental Traumatology guidelines for the management of traumatic dental injuries: 2. Avulsion of permanent teeth. Dent Traumatol 2012;28:88-96. Malmgren B. Ridge preservation/decoronation. J Endod 2013; 39(3 suppl):S67-S72.

to maintain the

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PART VII

Trauma Management

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CHAPTER

This chapter is dedicated to our

mentor; Dr James H . S . Simon ( 1934-2013 ).

Teeth with subcrestal fractures, subgingival caries, resorptive defects, or perforations in the cervical third of the roots are often condemned due to the difficulty of restoration or the violation of biologic width. Crown lengthening procedures are sometimes used to re- establish biologic width, but if the cavosurface margin is close to the osseous crest, crown lengthening may compromise the periodontal support of that tooth or adjacent teeth. Orthodontic extrusion is another option, but many patients are not willing to put up with the time and effort required, including the need for crown lengthening in the end. Another option to consider is immediate surgical extrusion. Immediate surgical extrusion consists of controlled luxation, repositioning of the tooth, and stabilization. It can be compared with extrusive luxation of teeth,1-3 which, according to Andreasen,4 - 5 has a favorable prognosis with a low occurrence of root resorption. Because the root never leaves the alveolar socket and the periodontal ligaments are kept moist and viable throughout the procedure, the potential harmful effects on the periodontal ligament cells are reduced.6

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Immediate Surgical Extrusion

Box 32-1

Procedural checklist for immediate surgical extrusion

Internally reinforce tooth structure. Ensure adequate visualization after flap reflection. Limit procedural trauma. Stain root structure with dye to detect defects. Reposition root at least 4 mm from alveolar crest.

Some of the potential indications for immediate extrusion include the following:

•To correct the pathologies in the coronal third of the root, such as subgingival caries, fractures, root perfo rations, and resorptive defects

•To rotate a tooth or root for restorative purposes •To reposition the intruded mature permanent teeth following trauma

•To maintain bone and esthetics in young, growing individuals with intact adjacent teeth for future implant placement

This chapter describes the controlled surgical extrusion of restoratively compromised endodontically treat ed teeth.

Check occlusion and clearance. Perform radiographic assessment of extrusion. Maintain flexible splinting for at least 2 weeks. Follow up at 4 weeks.

•Teeth with periodontal compromise, deep bony pockets, and/ or

mobility are poor candidates.

•Patients with compromised health and/or poor oral hygiene are poor candidates.

•The extruded root is narrower due to the natural root

.

taper A wider embrasure and altered emergence profile can result from changes in diameter and contour of the root and can be a restorative challenge. •Divergent roots and roots with multiplanar curvatures can be difficult to extrude.

Clinical Technique The clinical protocol for surgical extrusion is as follows (Box 32-1):

Armamentarium The materials and instruments required for immediate surgical extrusion are as follows:

•Periotome(s) •Forceps •Methylene blue dye •Sutures •Nylon fishing wire

•Composite resin

Clinical Considerations The following considerations should be taken into ac count when performing surgical extrusion:

final crown-to -root ratio should be at least 1:1. The root to be extruded should be long enough to support the future restoration. must be sufficient space available to extrude the There •

•The

tooth.

.

1 Initiate or complete root canal treatment. 2. Reflect a full-thickness envelope flap extended to one tooth on either side. 3. Use periotomes circumferentially in a root-down rocking manner to atraumatically luxate the root and sever periodontal ligament fibers. 4. With a forceps, passively reposition the root so that the deepest finish line is approximately 4 mm above alveolar crest (2 mm for biologic width and 2 mm for ferrule effect). An intraoperative radiograph can be taken to assess the degree of extrusion. 5. Reposition the flap and suture. 6. Check the occlusion. 7. Stabilize the tooth for 2 to 4 weeks with a flexible orthodontic wire or nylon fishing line bonded onto the adjacent teeth with composite resin. Make sure that the stabilization maintains the desired position of the tooth. 8. Prescribe 0.12% chlorhexidine mouthrinse to be used twice daily and recommend a soft diet. 9. Remove the sutures after 48 to 72 hours. 10. Reassess the stability after 4 to 6 weeks. Restore the tooth with an appropriate core buildup and proceed with the definitive restoration 11. Perform a clinical and radiographic follow-up.

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Clinical Cases

Fig 32-1 (a ) Preoperative radiograph showing fractured maxillary right central incisor crown with an exposed post, (b) Preoperative clinical view showing the crown fractured at the gingival level with an exposed post , (c) Endodontic treatment was completed in one visit. An interim restoration was placed with direct composite, (d ) Clinical view prior to immediate surgical extrusion.

This extrusion procedure is not without risks and complications. The tooth may fracture during repositioning. One can minimize this risk by placing temporary reinforcement with composite resin in the coronal section of the root. Marginal bone loss could result if the osseous housing is damaged by aggressive use of a periotome or forceps. Areas with thin cortical plate are especially susceptible to marginal bone loss from surgical trauma. One can minimize this risk by careful assessment of bone support and biotypes and by direct visualization of the periotome placement under adequate magnification and illumination after reflection of the flap.

Clinical Cases Case 32-1 A 41-year-old woman was referred for evaluation of a fractured maxillary right central incisor (Figs 32-1a and 32-1b). Clinical tests showed that all of her maxillary incisors were slightly tender to pressure but nontender to percussion. Radiographic examination revealed a small radiolucency at the apices of all of the incisors, which had been endodontically treated and restored with posts and crowns. The right central incisor was fractured at the gingival level with the post exposed to the oral environment. Various treatment options were discussed, including ( 1 ) extraction and replacement with an implant, a fixed bridge, or a partial denture; (2) endodontic retreatment with crown lengthening and restoration with a cast post and new crown; and (3 ) immediate surgical extrusion after endodontic retreatment. The patient chose option #3.

Endodontic retreatment of the maxillary right central incisor was completed in one visit, and the access was temporarily restored with bonded composite contoured to resemble a natural tooth (Figs 32-1c and 32-1 d). A sulcular incision was made, and a small labial flap was reflected (Fig 32-1e). With the root surface and alveolus exposed, methylene blue dye was painted on the root surface and subsequently rinsed with sterile saline after 1 minute to highlight any defects on the root surface. No obvious defects were detected. A periotome was then placed into the periodontal ligament space with firm apical pressure, and it was slowly worked around the root circumferentially until the root was sufficiently loosened. The tooth was then gently luxated with a forceps into the desired position (Fig 32-1f), and a radiograph was taken to ensure that the desired length had been achieved. The extruded root was stabilized with a flexible splint, and the flap was repositioned and sutured (Figs 32-1 g and 32- 1h). The patient was recalled 2.5 weeks later for splint removal (Fig 32-1i). At the 4-month recall, all of the maxillary incisors had been restored with cast posts and crowns, the endodontically re-treated anterior teeth were asymptomatic, and the radiolucency on the maxillary right central incisor showed osseous regeneration with normal architecture. The clinical and radiographic examination showed a harmonious gingival contour of the maxillary anterior teeth (Figs 32-1 j and 32-1k). At the time of this writing, approximately 7 years have passed since the immediate extrusion. Radiographic examination shows normal periodontal ligament space and normal lamina dura architecture, and there is no sign of external root resorption or ankylosis (Fig 32- 11). Clinical examination shows intact anterior crowns with a slight buccal gingival recession on the extruded tooth (Fig 32-1m).

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E3

Immediate Surgical Extrusion

Case 32-1 (cont )

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Fig 32-1 (cont ) (e) A flap was reflected, and a periotome was placed into the sulcus circumferentially with controlled apical pressure until the tooth was detached from the socket, ( f ) The tooth is elevated in the desired position, (g ) The tooth is splinted, the flap is sutured, and the occlusion is adjusted, ( h ) Immediate post -extrusion radiograph. Note the space between the alveolar sock et wall and the root, (i ) Radiographic check 2.5 weeks later at splint removal, ( j ) Clinical check 4 months after extrusion, ( k ) Radiographic check 4 months after extrusion. ( I ) Radiograph at 7 -year recall, (m ) Clinical view at 7 -year recall.

Case 32- 2 A 62 - year-old woman was referred for evaluation of a grossly carious maxillary left lateral incisor (Figs 32-2a to 32- 2c). Following a discussion of options available, the patient stated that she wanted to retain the tooth for as long as possible. Orthodontic extrusion was attempted

but was aborted due to insufficient space for activation of the orthodontic appliance (Figs 32-2d to 32- 2f). Immediate surgical extrusion was then performed (Figs 32-2g to 32- 2j). The splint was removed at 3 weeks, and the patient was recalled at 4 months (Fig 32- 2k) and 1 year (Figs 32-2I to 32- 2n).

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Clinical Cases

Fig 32- 2 (a ) Preoperative radiograph showing carious destruction of the maxillary left lateral incisor and its relationship to the alveolar crest and adjacent teeth ( b and c) Preoperative clinical views showing the compromised tooth structure, (d ) Orthodontic extrusion was attempted, fej Orthodontic extrusion was aborted due to inadequate space for activation of the orthodontic appliance, ( f ) Postoperative radiograph after completion of root canal treatment and placement of a temporary post, (g ) Reflection of an envelope flap and placement of a periotome. (h ) Controlled luxation of the tooth to the desired position and verification of occlusal clearance, (i) Immediate post -extrusion radiograph demonstrating the extent of extrusion. © The flap is repositioned and sutured. The tooth was provisionalized with composite for interim esthetics and flexible splinting for 3 weeks, ( k ) Clinical view prior to cementation of a crown at 4 months. (I ) Radiographic follow -up after 1 year shows slight periodontal ligament space widening, (m and n ) Postoperative clinical views at 1 year showing optimal gingival health and architecture around the permanent crown. ,

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Immediate Surgical Extrusion

References

Conclusion

1. Caliskan MK, Turkun M, Gomel M. Surgical extrusion of crown-root-fractured teeth: A clinical review. Int Endod J 1999;32:146-151. 2. Kahnberg KE. Surgical extrusion of root -fractured teeth—A follow-up study of two surgical methods. Endod Dent Traumatol 1988;4:85-89. 3. Kahnberg KE. Intra -alveolar transplantation. I. A 10-year follow -up of a method for surgical extrusion of root fractured teeth. Swed Dent J 1996;20:165-172. 4. Andreasen JO. Luxation of permanent teeth due to trauma. A clinical and radiographic follow-up study of 189 injured teeth. Scand J Dent Res 1970;78:273-286. 5. Andreasen JO. Traumatic Injuries of the Teeth. Copenhagen: Munksgaard, 1981:151-195. 6. Soder PO, Otteskog P, Andreasen JO, Modeer T. Effect of drying on viability of periodontal membrane. Scand J Dent Res 1977;85:164-168.

Immediate surgical extrusion can be considered as an alternative to crown lengthening and orthodontic extrusion to aid in restoring a damaged tooth and in cases where biologic width impingement is an issue.

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CHAPTER

Venkat Canakapalli, MDS Mithuna Vasudevan, MDS

Orthodontic Extrusion

Complicated crown fractures, perforations, root resorption, or caries in the cervical area of a tooth can create structural, esthetic, and periodontal problems. From a restorative standpoint, these con ditions can create isolation problems, making restoration difficult, if not impossible. Orthodontic extrusion or forced eruption is sometimes the best method for managing these issues by elevating sound tooth structure from within the periodontium and making it accessible for restorative treat ment. This method is more conservative than traditional surgical crown lengthening because no bone is sacrificed from the adjacent teeth. It has the added advantages of eliminating intrabony defects around the extruded tooth, maintaining gingival esthetics, and maintaining the crown-to-

root ratio.

A tooth can be extruded orthodontically with light forces as much as 1 mm a week without causing damage to the periodontal ligament or risking root resorption. Hence, most active treatments can be completed in 4 to 6 weeks. Once the tooth is in the proper position, it should be stabilized for the same length of time as active eruption (usually 4 to 6 weeks). In most cases, minor crown lengthening is necessary after completion of orthodontic movement. This chapter discusses orthodontic extrusion and presents a case report. The authors also pro vide basic guidelines and clinical considerations for patients that could benefit from orthodontic extrusion.

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EE1 Orthodontic Extrusion

Fig 33- 1 Examples of possible indications for orthodontic extrusion: (a ) subgingival or subcrestal fracture; (b) biologic width impingement; (c) reduction of localized angular bone defects; (d ) preimplant or atraumatic extraction; (e) traumatically intruded teeth.

Fig 33- 2 To ensure an adequate crown- toroot ratio, determine the amount of extrusion needed (4 mm in this case), subtract that amount from the apex, and compare the resulting crown- to- root ratio At least a 1:1 ratio is preferred.

.

Indications for Orthodontic

Clinical Considerations

Extrusion Root length

The indications for orthodontic extrusion include the following (Fig 33-1):

The crown-to-root ratio should be 1:1 or better at the end of treatment. When in doubt, several calculations should be made at the initial evaluation:

•Treatment of a subgingival or subcrestal lesion due to caries or oblique or horizontal fractures caused by a pin, post, or endodontic

•Perforations

1. Determine the amount of tooth that needs to be ex truded. At the end of treatment, there needs to be enough tooth above the alveolar crest to satisfy the biologic width of 2 mm, a sulcus depth of 1 mm, plus at least 1.5 mm for a ferrule. 2. Mark the new apex on a radiograph based on the amount of extrusion needed. From this point, mea sure to the alveolar crest and then to the incisal edge to confirm that a minimum ratio of 1:1 will be ob tained (Fig 33-2). 3. For easy calculation, these numbers are helpful: 3 mm are needed for the biologic width and sulcus; the crown margin should be at least 2.5 mm from the alveolar crest; and a minimum ferrule of 1.5 mm is necessary. Figure 33-2 shows a tooth that required 4 mm of extrusion.

treatment

•Subgingival root resorption •Biologic width impingements •Reduction of intrabony defects and isolated periodon-

tal pockets •Pre-implant extraction to maintain or re-establish the integrity of the alveolar ridge Orthodontic extraction where surgical extraction is • contraindicated ( eg, patients receiving chemotherapy, radiotherapy, or intravenous bisphosphonates) •Treatment of traumatically intruded teeth

Contraindications for Orthodontic Extrusion

Root form

Contraindications for orthodontic extrusion include the following:

External root form

•Ankylosis

or hypercementosis (the extra load would cause intrusion of the anchor teeth)

Most roots are tapered, and the cervical width in its final position needs to be compared with the current cervical width. If the root is quite tapered and the width is too narrow in its final position, esthetics may be compromised. A difference of 1 mm or less is ideal; 2 mm is a compromise, and 3 mm or more can cause black triangles or other esthetic compromises (Fig 33-3).

•Vertical root fracture

•Root proximity and premature closure of embrasures

•Short roots, which do not allow adequate support of a

restoration (crown-to-root ratio is less than 1:1) •Insufficient vertical space •Exposure of a furcation

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Clinical Technique Fig 33 - 3 The external root form has minimal taper, so 4 mm of ex trusion will result in less than 1 mm of loss in tooth width.

Fig 33- 4 Internal root form, (a) After the crown preparation, there will be adequate thickness of dentin, (b) The canal width is less than 1/3 of the total root width.

Internal root form

•How difficult is the restorative treatment, and what is

The thickness of the dentin wall in the cervical area with the tooth in its final position should be assessed. This is most likely to be an issue with root canal-treated teeth. The tooth must have adequate dentin thickness and strength after the crown preparation. At least 1 to 2 mm of remaining dentin thickness after crown preparation is considered adequate. In addition, the cervical width of the root canal space should occupy no more than 1/3 of the total root width (Fig 33-4).

•If it is a structurally compromised tooth, is the restor-

its long-term prognosis? ative dentist capable of restoring it adequately and obtaining a good esthetic result? •Will failure compromise future restorative options?

Clinical Technique 1. Bond orthodontic brackets to one or two teeth on ei-

ther side of the tooth to be extruded. 2. Bond a button on the facial surface of the tooth to be extruded. Position the button so that when the extrusion is complete, it will be level with the wire slot in

Smile line It is often worth going the extra mile (such as orthodontic extrusion) to retain a natural tooth in the esthetic zone of a patient with a high smile line. In many cases, a single natural tooth will provide better esthetics than a partial denture or implant. This is particularly true when

the brackets. 3. Secure a rigid archwire to the orthodontic brackets. As an alternative, a rigid rectangular archwire can be bonded directly to the adjacent teeth without the brackets. 4. Loop a rubber chain around the archwire, and secure both ends to the button. The rubber chain extrudes the tooth while the rigid base archwire maintains the space and prevents intrusion of the adjacent teeth. (A flexible cantilever spring can also be used. A single flexible archwire is generally not recommended because it moves all the teeth, and the adjacent teeth tend to tip toward the tooth being extruded.) 5. The patient should be seen every week or two to check the progress and reduce the incisal edge/occlusal surface to create space for the tooth to extrude. 6. Once the tooth is in the proper position, rigidly fix the button to the archwire and retain it for 4 to 6 weeks to allow the periodontium to finish remodeling. 7. Postorthodontic gingivectomy or crown lengthening is usually necessary to provide the proper gingival

two teeth are missing.

Patient factors Important considerations include the patient's goals and whether they are realistic; the patient 's age, medical history, and economics; and the patient's dental history, periodontal status, and oral hygiene.

Prognosis for endodontic and restorative treatments Important questions regarding prognosis include the

following:

•How difficult is the endodontic treatment, and what is

contours.

the prognosis?

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Orthodontic Extrusion

Fig 33- 5 (a) A fractured maxillary right lateral incisor following trauma. When the fractured coronal fragment was removed, some of the margins were subgingival, (b ) Preoperative radiograph, (c ) A post space was prepared, and a fiber post was bonded into the canal, (d ) Composite resin was used to build up the coronal portion of the tooth. Clear orthodontic brackets were bonded to the central incisor and canine, and a button was bonded to the lateral incisor core. A rigid archwire was attached to the brackets for anchorage, and a rubber elastic was wrapped around the wire and secured to the button, ( e ) Extrusion was confirmed with a radiograph, ( f ) A ligature wire was used to rigidly retain the extruded tooth, (g ) A gingivectomy was performed to establish the proper gingival contours and expose adequate tooth structure for a ferrule. In many cases, crown lengthening is necessary, ( h ) Ceramic crown after cementation. ( i) Postoperative radiograph, ( j ) Radiograph at 3-year recall.

Considerations for Orthodontic Root Extrusion

Case Report A 62-year-old man was referred for evaluation of a fractured maxillary right lateral incisor following trauma. Clinical examination revealed that his maxillary right lateral incisor was fractured at the level of the gingiva (Fig 33- 5 a). Radiographic examination revealed that the tooth had been endodontically treated, and there was no periapical radiolucency (Fig 33-5b). Various treat ment options were discussed, including ( 1 ) extraction and replacement with an implant or partial denture; (2 ) crown lengthening and restoration with a cast post and new crown; and (3 ) orthodontic extrusion with a post and new crown. The patient chose option no. 3. Root length and external and internal root forms were assessed and were considered ideal for orthodontic extrusion. The periodontal status of the adjacent teeth was assessed regarding their ability to provide anchorage. A post space was prepared, a fiber post was cemented

•Ideally, root canal treatment and at least the initial restorative treatment should be completed prior to orthodontic extrusion. In some cases, retreatment is necessary.

•If there is a fracture that involves the labial enamel, the

fragment should be retained (if possible) because it is easier to bond to enamel than restorative materials. •An open embrasure (black triangle) can occur on the mesial and/or distal aspect of the tooth as it is extruded (due to the distance of the contact point from the alveolar crest or the shape of the tooth). When this occurs, the mesial aspect of the tooth can sometimes

be reshaped to improve the contact point and embrasure, and the tooth can be moved slightly toward the midline so the greater space on the distal aspect can

be restored.

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Recommended Reading (Fig 33- 5 c), and a preliminary core buildup was placed to retain an orthodontic bracket (Fig 33 - 5 d). Orthodontic extrusion was initiated with anchorage from adjacent

Summary Orthodontic extrusion is a viable alternative for certain patients who are motivated to try to retain a tooth. When properly applied, it can improve restorability, making it a useful technique in clinical practice.

teeth. The tooth was assessed weekly, and adequate extrusion was achieved in 4 weeks. This was confirmed with a radiograph (Fig 33- 5 e). The tooth was retained for 6 weeks with a ligature wire. Tooth stability and radiographic healing were confirmed prior to debonding (Fig 33-5f). After the brackets were removed, a gingivectomy was performed, followed by the final tooth preparation (Fig 33-5g). Figure 33- 5h shows the cemented ceramic crown, and Fig 33- 5i shows the healed periapical bone. A radiograph taken at the 3-year recall shows normal bony architecture (Fig 33- 5 j). The tooth was asymptomatic and functional. The final outcome was satisfactory, and the patient was happy with the result, especially considering the guarded to

Recommended Reading Bach N, Baylard JF, Voyer R . Orthodontic extrusion: Periodontal considerations and applications. J Can Dent Assoc 2004;70: 775-780.

Proffit WR, Fields HW, Sarver DM. Contemporary Orthodontics, ed 4. St Louis: Mosby, 2006.

poor restorative prognosis at the outset.

Acknowledgment This chapter was based on the lecture series recorded for the American Association of Orthodontists by the late Dr Vincent G. Kokich.

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CHAPTER

Clinical Richard Schwartz, DDS Marga Ree, DDS, MSC

Management of

Horizontal

Horizontal root fractures are a fairly common result of oral trauma. If the fracture occurs at or coronal the alveolar crest, the prognosis is poor and treatment options are limited. Occasionally, with a very long root, the coronal segment can be removed, and forced eruption of the apical segment can be performed. If the fracture is in the middle or apical third, the prognosis is generally good. Horizontal fractures occur most often in the anterior teeth (Fig 34-1), but they can occur in any tooth. Sometimes they occur on only one root of a multirooted tooth (Fig 34-2). These fractures are often nondisplaced, asymptomatic, and only detected on radiographs, sometimes years later. Nondisplaced fractures may require multiple vertical angles for visualization on periapical radiographs. Cone beam computed tomography (CBCT) can be very helpful in identifying horizontal fractures (Fig 34-3), including whether they are displaced, the angle of the fracture line, and any associated alveolar fractures. The pulp remains vital in the coronal segment about 75% of the time, even with some dislocation of the segments (Fig 34- 4). The pulp remains vital in the apical segment close to 100% of the time. In many cases, one or both segments develop pulp canal obliteration (PCO). The apical segment sometimes " floats" away from the coronal segment over a period of years (Fig 34-5). Teeth with horizontal fractures often survive many years without treatment (Figs 34-6 and 34-7). In the absence of clinical signs or symptoms or radiographic changes, the protocol for management of horizontal fractures is periodic recall, radiographs, and pulp testing. If the coronal segment is mobile, it should be splinted to the adjacent teeth for 4 to 6 weeks. If the root fracture is near the cervical area, the splint should be maintained for up to 4 months.

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Clinical Management of Horizontal Fractures

Fig 34- 1 Horizontal fractures Fig 34- 2 A horizontal fracture in the mesioare usually seen in anterior buccal root of a maxillary right first molar. Horteeth like this maxillary right izontal fractures occasionally occur in premocentral incisor. (Courtesy of Dr lars and molars. Michael Pascal, Washington, DC.)

Fig 34- 3 CBCT images can be Fig 34-4 Trauma caused this very helpful in identifying horizon- horizontal fracture 5 years earlier, tal fractures. The interproximal (in Even with the unfavorable locathis case, sagittal) view is partic - tion of the fracture and significant ularly useful. This CBCT image separation of the segments, the shows the same tooth as in Fig coronal segment responded nor34-1. Note the typical oblique mally to cold. It was slightly moangle of the fracture. (Courtesy of bile but was asymptomatic and Dr Michael Pascal, Washington, functional. DC.)

Fig 34- 5 (a) A horizontal fracture of the maxillary left central incisor occurred as a result of trauma. No treatment was rendered other than periodic recalls. Recall radiographs are shown at approximately 1 (b), 4 (c), and 10 (d) years. Note that both segments underwent PCO and resorption, while the apical segment drifted away from the coronal segment.

Fig 34- 7 A 15 - year recall after a bicycle accident. Fig 34-6 (a and b ) Trauma caused horizontal fractures of the central incisors 25 years earlier. The teeth were slightly mobile but functional and asymptomatic . (Courtesy of Dr Ahmad Tehrani, Plano, Texas.)

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Clinical Management of Horizontal Fractures

Fig 34- 8 Treatment through the fracture line with gutta- percha almost guarantees failure. This patient presented with pain and swelling, (a ) Both segments had undergone root canal treatment 2 months earlier, (b) The gutta-percha was removed from the coronal segment , (c and d ) The coronal segment was obturated with MTA, and the apical segment was surgically removed.

Fig 34- 9 It is generally advisable to perform root canal treatment only in the coronal segment when treatment is necessary. In this case, the referring dentist had already instrumented both segments, so there was no choice, (a ) The canal was prepared in both segments, ( b ) A calcium hydroxide dressing was placed for a few weeks, (c) Both segments were obturated with MTA. (d and e ) A flap was reflected, and the extruded MTA was removed from the fracture site, ( f ) Radiograph at the 2-year recall, (g and h ) Radiograph and sagittal CBCT image at the 7.5 -year recall.

For those teeth that require treatment, root canal

and obturated with gutta-percha, the failure rate is close 100% (Fig 34-8). If both segments have already been treated and the clinician does not want to remove the apical segment, both segments can be obturated with MTA followed by surgical exposure and cleanup of the fracture site (Fig 34-9).

treatment should be performed only to the fracture line. The authors typically place a plug of mineral trioxide aggregate (MTA) or bioceramic putty (Brasseler). There is rarely a need to remove the apical segment When root canal treatment is performed through the fracture line

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Clinical Technique for Horizontal Fractures

Clinical Technique for Horizontal Fractures

10. If the tooth requires treatment due to clinical or radiographic signs or symptoms, follow the protocol outlined here: 11. Reposition and apply a splint if necessary (Fig 34-10a) 12. Make access and perform a pulpectomy in the cor-

The authors clinical protocol for managing horizontal fractures is as follows:

.

onal segment. Take care not to disturb the apical segment. 13. Determine the working length, which can be tricky (Fig 34-1Ob). An electronic apex locator may not provide accurate measurements. Because the fracture lines are usually oblique, periapical radiographs can be misleading. CBCT imaging is sometimes

1. Determine mobility and whether the coronal segment has been displaced. Make sure that the tooth is not in traumatic occlusion and does not interfere with normal closure. If the tooth has mobility greater than 1, plan to place a splint. 2. Take periapical radiographs from multiple vertical angles. Take a CBCT scan if it is available. 3. Determine the pulpal response to cold of the fractured tooth as well as the other teeth possibly involved in the trauma. 4. If necessary, reposition the coronal segment and splint it to the adjacent teeth. In most cases, the authors use a rigid, rectangular wire or a titanium trauma splint (Medartis AG). Sometimes the coronal segment needs to be repositioned apically as well as laterally. If there are multiple loose teeth, it may also be necessary to bond the interproximal areas together in addition to the splint. 5. Check again to make sure that there is no occlusal

helpful if viewed from the interproximal aspect to visualize the angle of the fracture line and estimate the working length. It is better to estimate too short than too long. 14. Thoroughly clean and shape the canal, and place calcium hydroxide paste or powder (Fig 34-10c). Schedule an appointment in 1 month. 15. If the patient's clinical signs and symptoms have resolved and the tooth looks satisfactory radiographically, treatment can be completed. The authors typically change the calcium hydroxide at this appointment and complete treatment at 3 months because of concerns about inflammatory resorption. 16. Place an MTA plug or a bioceramic putty to the fracture line (Fig 34-1Od) and obturate the rest of the canal with gutta-percha and composite or with composite and a fiber post (Fig 34-1Oe). The authors place the MTA with a Dovgan carrier (Quality Aspirators) and use a flat-ended, fitted gutta-percha point as a plugger. The MTA plug will become denser if indirect ultrasonic vibration is applied against a fitted metal plugger. Once each aliquot of MTA is in place, the fat end of a paper point is used to further condense it, absorb the excess moisture, and fix it in place. 17. Recall (Fig 34-1Of).

.

trauma

6. Recall at 1 month. Take a periapical radiograph and repeat the pulp tests. Look for signs of bone loss or inflammatory resorption. Check tooth mobility by

detaching the fractured tooth from the splint. If the mobility is reduced to 1 or less, remove the splint. 7. Recall at 2 months and repeat step 6 as necessary. In most cases, the splint can be removed at this point if it is still in place. 8. Recall at 6 months for radiographs and pulp testing. 9. Advise the patient and /or parents of the signs and symptoms that indicate a problem: pain, swelling, discoloration of the tooth, or a sinus tract. If any of these conditions occur, the patient needs to come in before the next scheduled recall appointment.

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Clinical Management of Horizontal Fractures

Fig 34-10 This patient presented with a horizontal fracture, (a ) The coronal segment was displaced lingually and incisally. The tooth was repositioned and splinted ( b) Working length was established ( c) The canal was cleaned and shaped to the fracture line, and calcium hydroxide was placed, (d and e) At the second appointment , an MTA plug was placed to the fracture line, and the tooth was obturated and restored, ( f ) Eight -year recall radiograph. ,

,

Fig 34-11 (a ) The patient presented with a history of a horizontal fracture and root canal treatment in both segments, ( b and c) was retreated and obturated with MTA to the fracture line, (d and e) The apical segment was surgically removed in two pieces ( ) The coronal segment f Periapical radioqraph immediately after surgery, (g and h ) Periapical radiograph and sagittal CBCT slice at 5 years.

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Recommended Reading Fig 34 -12 Teeth splinted with a titanium trauma splint.

Case Report

Summary

A 13-year-old boy presented with persistent pain following a traumatic injury to his maxillary right central incisor. Root canal treatment had been performed erroneously in both segments (Fig 34-11a). The diagnosis was horizontal fracture with previous root canal treatment and acute apical periodontitis. The treatment options presented to the patient and his parents were (1 ) retreatment of the coronal segment and surgical removal of the apical segment; and (2) removal of the entire tooth. The patient and his parents opted for the first option Retreatment was completed in the coronal segment, and the canal was obturated to the fracture line with white MTA (Figs 34-11b and 34-11c). A labial flap was reflected (Fig 34-11d), and the apical segment was removed. Because of the oblique nature of the fracture, the root end had to be sectioned and removed in two pieces (Fig 34-11e). The patient's symptoms resolved after the surgery, and healing was uneventful. Periapical radiographs are shown immediately after surgery (Fig 34-11f) and at 5 years (Fig 34-11g), and a sagittal CBCT slice at 5 years is also shown (Fig 34-11h).

The majority of teeth with horizontal fractures require no treatment. In the absence of clinical signs or symptoms or pathologic radiographic changes, recall the patient

for periodic pulp testing and radiographs. When root canal treatment is necessary, treat only to the fracture line and obturate with MTA or bioceramic materials If both segments were previously treated and are failing, retreatment of both segments may be possible with MTA or bioceramic materials. In most cases, surgery will also be necessary to " clean up " the area of the fracture and/or remove the apical segment.

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.

Recommended Reading American Association of Endodontists. Recommended Guidelines of the American Association of Endodontists for the Treatment of Traumatic Dental Injuries, http:// www. aae.org/ uploadedfiles/publications_ and_research/ guidelines_and_ position_ statements/ 2004traumaguidelines.pdf. Accessed 7 October 2014. Cvek M, Mejare I, Andreasen JO. Conservative endodontic treatment of teeth fractured in the middle or apical part of the root. Dent Traumatol 2004;20:261-269. The Dental Trauma Guide 2010. www.dentaltraumaguide.org. Accessed 7 October 2014.

Clinical Tips •At recall appointments, for teeth splinted with an or-

thodontic wire, detach the injured tooth and check for mobility. If mobility has not reduced sufficiently, it can be reattached to the wire with little effort. •For large canals, calcium hydroxide powder does not tend to wash out like paste. •A titanium trauma splint provides excellent stabilization if there is adequate tooth structure available for bonding (Fig 34-12). •It is the authors' experience that MTA and bioceramic putty can be used somewhat interchangeably.

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CHAPTER

Michael Trudeau, DDS

Clinical Management of Incisors with

Dental trauma is experienced by approximately one-third of all individuals, most commonly between the ages of 8 and 13 years. Management of traumatic injuries can be complex, including endodontic, periodontal, restorative, and/or esthetic considerations, and mismanagement of teeth with crown fractures is fairly common. The management of patients with complex crown fractures (those including the pulp) is dictated by a number of factors: tooth development, vitality, remaining tooth structure, and detached or partially attached fragments. Thinking about long-term outcomes helps guide us in the best management of these patients. Vital pulp therapy is usually the treatment of choice for a tooth with a vital pulp and incomplete root development. This can be performed with calcium hydroxide or one of the bioceramic materials, such as mineral trioxide aggregate (MTA). Continued root development increases the thickness of the dentin walls and strengthens the tooth, which is likely to extend its functional life. Traditional root canal treatment, on the other hand, often weakens the tooth. For most fully developed teeth, however, traditional root canal treatment is preferred over vital pulp therapy. When a clean fracture of the incisal segment occurs and all the fractured margins are in enamel, rebonding can provide a result that is esthetic and quite durable. This chapter outlines a clinical technique for rebonding a tooth segment in several different scenarios of complex crown fracture.

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Clinical Technique

Fig 35-1 The MAP System allows for precise placement of MTA.

Fig 35-2 Teflon tape works well for wrapping adjacent teeth to prevent resin bonding.

Fig 35- 3 OpalDam resin is used to tack the Teflon tape in position during bonding procedures.

Fig 35 - 5 Sanding strips are used for interproximal composite removal, finishing, and polishing. Fig 35 -4 Clear bite registration material is used to make the positioning jig.

4. If the fracture line is apical to the contact point, wrap the adjacent teeth in white Teflon tape to prevent composite adhesion when the fragment is rebonded. 5. Tack the Teflon tape in place with OpalDam composite resin. 6. Replace the fragment as closely as possible to its original location. In many cases, it will fit perfectly back to its original position. 7. Create a positioning jig for the tooth using a bite

Armamentarium •MTA delivery device such as the MAP System (Dentsply) or amalgam carrier (Fig 35-1) Teflon tape (Fig 35-2) • composite resin (Ultradent) (Fig 35-3) OpalDam • registration material (Dentsply) (Fig 35-4) bite Clear • (Dentsply) (Fig 35-5) strips Sanding • and wooden wedges band matrix Metal •

registration material (preferably clear). Holding the fragment with either cotton forceps or a finger, flow the quick-setting polyvinyl material over the fragment and tooth as well as the adjacent teeth. After it polymerizes, remove your finger (or forceps) and add another aliquot of material to complete the jig. Remove the jig and fragment together. The jig will act as a handle for the rest of the procedure. Make a practice run of placing the fragment on the tooth before you attempt bonding to make sure that the jig draws and seats the fragment correctly. 8. Etch and bond the tooth, and then etch and bond the fragment. Place a thin layer of dual-curing composite on the fractured portion of the tooth. Then, using the positioning jig, seat the fragment completely. If clear bite registration material is being used, the composite resin may be light cured through the jig. If not, allow adequate time for complete polymerization of the self-curing component of the composite resin.

Clinical Technique The clinical protocol for management of a complex fracture is as follows:

1. While the tooth is still wet, and before placing rubber dam, determine the appropriate composite shade should composite be needed at the end of the procedure. 2. Place rubber dam using multitooth isolation, and ensure that the fragment will complete the clinical crown and that there are no missing pieces. 3. Perform a pulpotomy or nonsurgical root canal

.

treatment

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PH Clinical Management of Incisors with Complex Fractures

Fig 35 - 6 (a ) Periapical radiograph shows an immature maxillary central incisor, (b) A high- speed diamond bur with water spray was used to remove 3 mm of pulp tissue, (c) White MTA was placed over the pulp (d ) The fragment after bonding, (e) Postoperative radiograph showing the MTA and bonded fragment, ( f ) Radiograph at 1 year. Note the dentin bridging, (g ) Radiograph showing dentin bridging and increased pericervical dentin at 3 years, ( h ) Radiograph showing the refractured tooth 4 years after initial treatment. ,

9. Remove the jig and light cure again from the facial

long-term prospects for this tooth could be improved by further root development. An MTA pulpotomy was chosen as the therapy of choice. An initial shade was chosen, the patient was anesthetized, and rubber dam was placed. A 0.014 Crown and Bridge Bur (Patterson) was used at high speed with water spray to remove 3 mm of pulp tissue (Fig 35-6b). A cotton pellet soaked in Lidocaine with 1:50,000 epinephrine was used to achieve hemostasis. White MTA (Dentsply) was placed using the MAP System and Dovgan pluggers (Fig 35-6c). The superficial layer of MTA was air-dried for 15 to 20 seconds and lightly burnished with a plugger. The dry MTA surface is less susceptible to washout during the bonding procedures. The fragment was bonded to the tooth in its original position (Fig 35-6d). The patient was followed over the next 4 years (Figs 35-6e to 35-6g). Dentin bridging occurred apical to the MTA, and the tooth continued to develop, increasing dentin thickness in the important pericervical area After 4 years, the patient refractured the tooth in the same place while playing basketball (Figs 35 -6h and 35-6i). Staining of the crown had occurred, which is typical of both white and gray MTA (Fig 35-6j). Because the tooth had now completed development and a thick dentin bridge was present, it was decided to remove the MTA and try to improve the esthetics with bleaching before

and lingual aspects. 10. If the fracture line is visible, a composite veneer may be employed to camouflage the line. Make short vertical depth cuts with variable depths using a 0.014 diamond bur. 11. Etch and bond the prepared area of the tooth and bonded fragment. 12. Place a thin facial veneer of the composite you selected at the start. 13. Finish and polish the composite. 14. Using composite finishing strips, remove any composite flash from the interproximal areas, finish, and polish.

Clinical Cases

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Case 35 -1 An 8- year-old girl fractured her maxillary left incisor. She presented with a crown fracture and pulp exposure. The periapical radiographs suggested incomplete root formation and an open apex (Fig 35 -6 a). The author felt that the

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Clinical Cases

Case 35-1 (cont )

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Fig 35 - 6 (cont ) (i) Photograph of the reinjured maxillary incisor, (j ) MTA staining shown from the lingual aspect, ( k ) Dentin bridge after removal of the MTA. (I) The tooth color was close to ideal after 1 week of internal bleaching (m) While the fractured segment was held, the bite registration material was applied ( n ) The remaining dose of bite registration material was applied (o) Fabricated positioning jig and fractured segment, ( p) Etching and bonding of the fractured tooth, (q ) Etching and bonding of the fractured segment using the jig as a handle, ( r ) Fragment bonded in place. ( s ) Vertical camouflage cuts were placed perpendicular to the fracture line at variable depths, (t ) Postoperative clinical view. ( u ) Postoperative radiograph. ,

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rebonding the fragment. The MTA was removed, and the dentin bridge was observed (Fig 35 -6k). A thin layer of Vitrebond glass-ionomer liner (3M ESPE) was placed over the dentin. Sodium perborate powder was placed into the cavity and sealed with Cavit (3M ESPE). One week of bleaching resulted in a good color match with the adjacent and contralateral teeth (Fig 35 -6I). A composite shade was taken before desiccation occurred, rubber dam was applied, and the fragment was reapproximated. In order to create the mounting jig, the first aliquot of clear bite registration material was applied to the mesial aspect of the tooth while the fragment was held in position (Fig 35-6m). After the finger positioning, it was removed and a second aliquot of bite registration was applied so that it extended to the adjacent teeth on both sides (Fig 35 -6n). The material was allowed to set for 1 minute. The resulting matrix acted as a positioning jig for the fragment. The jig was removed, and the fragment came with it (Fig 35-6o). There were no undercuts that prevented smooth placement of the fragment back to

the tooth. Both the tooth and the fragment were etched and bonded (Figs 35-6p and 35-6q). The Luxacore shade A 2 (DMG) was placed onto the tooth, and the fragment was joined to the tooth using the jig. Because the bite registration material was clear, the Luxacore could be cured through the jig. Multiple 20-second applications of light were applied from the facial, occlusal, and palatal aspects, and the jig was removed, leaving the fragment securely bonded in place (Fig 35- 6r). Residual composite resin at the bonding interface prevented the fragments from joining perfectly, so the fracture line was visible. This area was " camouflaged " with a thin veneer of composite resin. Vertical cuts were made with the Crown and Bridge Bur at variable depths (Fig 35-6 s). A metal matrix band was placed, and after etching and bonding, a thin lay er of microhybrid composite (Point 4, Kerr) was applied. The composite was finished and polished (Figs 35-6t and 35-6u). In addition to improving the esthetic result, the veneer is likely to aid retention of the fragment over time.

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EP1 Clinical Management of Incisors with Complex Fractures

Fig 35-7 (a ) Facial view of the fractured right maxillary central incisor, (b ) Palatal view showing pulpal involvement , (c) Preoperative radiograph (d ) Fractured tooth after the exposed end of the fiber post was trimmed away and the adjacent teeth were wrapped in Teflon tape (e ) Mounting jig and tooth fragment , ( f ) The tooth after bonding and preparation for a composite veneer, ( g ) The tooth after finishing and polishing of the veneer. Note the dehydration of the rebonded fragment, ( h) Radiograph showing good approximation of the fragment. ,

,

A jig was fabricated as previously described (Fig 35 -7e). The fragment and the tooth were etched and bonded, and the fragment was bonded in place using Luxacore dual-curing composite (Fig 35 -7 f). This procedure was performed prior to the introduction of clear bite reg istration material, so the jig was left undisturbed for 5 minutes while the Luxacore underwent chemical polymerization. A composite veneer was placed to mask the fracture line and provide some strength to the fractured segment. The fragment often looks chalky and dehydrated on completion (Fig 35-7 g) and takes a few hours to rehydrate and return to a normal appearance. The final radiograph shows good reapproximation of the fragment (Fig 35 -7h).

Case 35- 2 A 22- year-old man injured his tooth playing basketball. The tooth fractured through the pulp, and the fragment was found and brought to his dental appointment (Figs 35 -7 a and 35-7 b). The periapical radiograph showed a completely developed maxillary incisor with a fully developed apex (Fig 35-7 c). The endodontic management of this case included nonsurgical root canal treatment, placement of a fiber post, and rebonding of the tooth fragment. Anesthetic was delivered, and multitooth rubber dam isolation was achieved. The canal was instrumented and obturated using warm vertical condensa tion. In this case, a decision was made to place a fiber post to help prevent a snap - off failure in the future at the level of the gingival margin. The gutta -percha was removed using a #2 Peeso drill. This preparation corresponds to a 0.5 DT Light- Post (Bisco). The sealer was removed using alcohol, and the canal was etched and bonded using Clearfil bonding products (Kuraray). Luxacore was injected into the canal using a Centrix gun, and the fiber post was placed in the canal. The excess unset composite was removed with microbrushes. Af ter the composite was polymerized, the fiber post was trimmed flush with the tooth. Because the tooth fractured below the contact point, Teflon tape was applied to the adjacent teeth (Fig 35 -7 d) to prevent composite from bonding to them. A wedge was placed to create interproximal space for the fragment to seat completely.

Case 35-3 A 16- year-old boy was hit in the mouth with a baseball, causing a crown fracture that exposed the pulp (Figs 35 - 8a and 35 - 8b). The fragment was brought to the

dental appointment. The radiograph suggested that the root was mature and the apex was fully formed, so nonsurgical root canal therapy was indicated. A decision was made to extend the fiber post into the fragment. The potential benefit to this approach is that it may prevent the tooth from refracturing, although there is increased risk that the fragment itself may be more susceptible to fracture. Multiple-tooth rubber dam isolation was achieved, and the nonsurgical root canal treatment

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Summary

Case 35-3

Fig 35 - 8 (a ) Radiographic view of a fractured maxillary left central incisor, (b) Multiple-tooth isolation of the fractured tooth, (c) Radiograph of the completed obturation, (d ) Radiograph after the fragment was bonded, with the fiber post extending through both segments, (e) The fiber post was bonded in place with Luxacore composite, ( f ) Postoperative radiograph showing the completed endodontic and restorative management of the fractured tooth. (g ) One-year recall ( h ) Clinical photograph at 1 year. ,

was performed (Fig 35 - 8c). The adjacent teeth were wrapped with Teflon tape, and a positioning jig was fabricated using clear bite registration material. A small amount of Cavit was placed to prevent composite from extruding into the canal. The fragment was rebonded using Luxacore composite. The fit of the fragment was such that the horizontal fracture line was imperceptible, so a composite veneer was not necessary. A lingual access preparation was made that extended into the incisal edge, and a fiber post was fitted ( Fig 35- 8d). The canal was etched and bonded. The post was luted with Luxacore dual-curing composite resin delivered with a Centrix gun (Fig 35 - 8e) . After polymerization, the exposed end of the post was cut back and the access was countersunk with a bevel in enamel. A thin layer of restorative composite resin was bonded to the lingual aspect of the tooth to cover the end of the post. The mounting jig allowed good approximation and bonding of the fragment (Fig 35 - 8f). Figures 35- 8g and 35 - 8h are from the 1-year recall appointment.

Clinical Tips •MTA has been used because

it predictably causes a dentin bridge over the pulp. Biodentine (Septodent) or other bioceramic materials show promise in providing the same bridge without staining. •When immediate bonding is desired over fresh MTA, a thin layer of resin or glass- ionomer restorative material can be placed to protect the MTA and prevent wash out during bonding procedures.

Summary A positioning jig can facilitate the replacement of a fragfractured tooth in a variety of clinical scenarios. The patient and the clinician can expect a favorable

ment on a

esthetic outcome from the procedure.

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PART VIII

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CHAPTER

Marga Ree, DDS, MSC

Clinical Management of Teeth with Open Apices with the Apical Barrier Techni

Treatment of young permanent teeth with pulpal involvement is an endodontic and restorative challenge. When pulp vitality is lost, the formation of dentin stops, resulting in a tooth with thin dentin walls that is prone to fracture. Traditionally, apexification has been performed with calcium hydroxide. This is a lengthy procedure requiring 5 to 20 months of treatment1 and multiple appointments. During this period, the tooth is restored temporarily and is prone to fracture. In addition, several in vitro studies reported a reduction in the mechanical properties of radicular dentin after exposure to calcium hydroxide for 5 weeks or longer.2 Mineral trioxide aggregate (MTA) was introduced in 1993 and has been studied extensively since that time. It is widely used as an apical barrier in immature, nonvital teeth as an alternative to calcium hydroxide.3 MTA is a bioactive material with excellent biocompatibility, good sealing, and antimicrobial properties.4 MTA has several drawbacks, including a long setting time, high cost, difficult handling properties, and dentin discoloration.3,4 Other bioactive materials have been developed that can be used for apical barriers. These include EndoSequence Root Repair Material (ERRM) putty (Brasseler) and Biodentine (Septanest N, Septodont). These are referred to as bioceramics. The new generation of bioceramic putties have indications that are similar to MTA, but they offer some advantages. In general, they have better clinical handling properties, and there have been no reports of staining. Some bioceramic products set faster than MTA. The majority of papers report favorable properties, similar to MTA, including biocompatibility, bioactivity, minimal microleakage, and antimicrobial properties.5-10 While in vitro studies are promising, it is not clear if any of these results influence clinical success.

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3

3

Clinical Management of Teeth with Open Apices with the Apical Barrier Technique

Fig 36-1 (a and b) MTA powder and liquid are mixed together until it has a consistency of wet sand, (c) Any surplus moisture can be absorbed with a cotton roll (d and e ) The MTA is loaded into a carrier, which delivers a small pellet of material as deeply as possible into the canal. ,

Extraradicular Matrix

3. If the patient is asymptomatic after 3 to 4 weeks and there are no clinical signs of infection, proceed with

Controversy exists about the need for a matrix to prevent extrusion of the barrier material The use of a biocompatible matrix is reported to provide more control during the delivery of the apical plug.11 Several matrix materials have been recommended, including demineralized freeze- dried bone, collagen sponges, and calcium sulfate. The author prefers the use of calcium sulfate because it is a biocompatible material that resorbs in a few weeks and has the longest clinical history as a synthetic bone graft material.12-14

4. If signs or symptoms remain, or if inflammatory resorption is present, perform additional debridement and irrigation and reapply the calcium hydroxide for

.

treatment

.

another month.

5. If the canal can be dried, place an apical plug. 6. For a wide-open apex, place a matrix of calcium sulfate past the apex to contain the apical barrier material. 7. Mix the calcium sulfate to a consistency of wet sand. 8. Insert the MTA carrier loaded with calcium sulfate as deep as possible, preferably beyond the apical foramen, and apply several increments of the material into the periapical tissues, filling the bone defect to the cavosurface of the open apex. Check its placement with a radiograph. The material should set after a few minutes. 9. Mix the apical plug material according the manufacturer's instructions. 10. The consistency of MTA should be similar to that of wet sand (Fig 36-1). 11. When using Biodentine, follow the user's manual for mixing the material. It should have a puttylike consistency after it is mixed (Fig 36-2). 12. ERRM putty is premixed and ready to use (Fig 36-3). Remove the desired amount of material using a sterile instrument, and place the putty on a clean glass slab or dappen dish. Immediately after removing the material, place the lid back on the jar so that it does

Reinforcement of Thin Root Walls Immature anterior teeth are at risk for root fracture after root canal treatment. Following the apical barrier placement, immature teeth can be strengthened with restorative materials. Current evidence, mostly from laboratory 15 studies, suggests that composite resin materials and fiber 16-18 posts enhance the fracture resistance of pulpless teeth.

Clinical Technique for Apical Barrier Placement

not dry out.

The clinical protocol for apical barrier placement is as follows:

13. Apply the apical plug in small increments. 14. Use a thick paper point as an initial plugger for MTA to absorb the surplus of moisture (Fig 36-4a). Insert a metal plugger, and activate it with indirect ultrasonic vibration to create a dense MTA plug (Fig 36-4b). 15. When using Biodentine, insert a metal plugger and gently tap the material in an apical direction.

1. Control the infection with mechanical and chemical

debridement of the root canal.

2. Place an interappointment dressing of calcium

hydroxide.

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Clinical Technique for Post Placement Fig 36 - 2 (a and b ) Biodentine powder comes in a capsule to which liquid drops are added. It is triturated for 30 seconds to a puttylike con-

.

sistency

Fig 36-3 (a and b ) ERRM putty is premixed and

b

sets upon contact with moisture.

Fig 36-4 (a ) A thick paper point may be used as a plugger with MTA to absorb any surplus moisture, (b ) The use of indirect ultrasonic vibration results in a dense MTA plug.

16. When using ERRM putty, use a thick custom-made gutta-percha cone as a plugger, and gently tap the material in an apical direction. Another option is to use a metal plugger with a small amount of BC Sealer (Brasseler) on the tip and gently tap the putty in place. 17. Check the placement of the apical plug with a

Clinical Technique for Post Placement The clinical protocol for post placement is as follows: 1. Verify that the apical plug has set hard. 2. Fit the thickest post that can be placed passively into the existing space. If there is still space, consider

radiograph. 18. Remove the remnants of the used material from the canal wall with a microbrush moistened with alcohol

.

placing more than one post. 3. Soak a fiber post in 24% hydrogen peroxide for 1 minute to etch the surface and improve composite bonding. This will dissolve the superficial layer of the resin matrix in which the fibers are embedded, so more fibers are available for silanization. Clean the post with phosphoric acid, rinse and dry, and apply silane, followed by a dental adhesive. Gently air-dry. The post is now ready to be placed.

or water

19. Insert a moist foam pellet on top of the apical plug, apply calcium hydroxide in the remaining part of the canal, and provisionalize the tooth.

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3

Clinical Management of Teeth with Open Apices with the Apical Barrier Technique Fig 36-5 (a and b) A needle tube can be used to place composite resin to the level of the MTA plug.

4. Condition the enamel and dentin with a three-step dental adhesive system: ( 1 ) acid etch, (2 ) apply the primer, and (3 ) apply the adhesive according to the manufacturer 's instructions. 5. Use a chemical or dual-curing core material that will flow through a needle tube (Fig 36-5). 6. Fill the post space with the core material. Insert the post(s) and wait for the composite to autopolymerize. If using a dual- curing material, apply the light after the material is hard. 7. Cut back the post to 2 mm below the cavosurface, apply silane and a dental adhesive to the top of the post, light cure, and restore the remaining space with a light-cured composite.

applied to the periapical tissues with an MTA carrier (Fig 36-6f) and allowed to set, and ProRoot MTA (Dentsply) was applied against the matrix to a thickness of 5 mm with a Dovgan MTA carrier (Figs 36-6g and 36-6h). A moist foam pellet was placed over the MTA, and the tooth was provisionalized. After 3 weeks, the patient returned for a definitive composite restoration (Fig 36-6i). At the 1-year recall, the patient was asymptomatic, the radiolucency had decreased in size, and there were no signs of root resorption (Figs 36-6j and 36-6k). Radiographic and clinical examination after 3 and 7 years revealed complete resolution of the radiolucency and a healthy tooth in full function (Figs 36-6I to 36-6o).

Case 36- 2

Clinical Cases

A 7-year-old girl developed a sinus tract following a traumatic dental injury to her maxillary right central incisor 9 months earlier. The tooth was luxated, and after repositioning, a splint was applied. When she developed a sinus tract, root canal treatment was started, and calcium hydroxide was placed as an intracanal medicament. The sinus tract persisted, and the patient was referred for further treatment. Clinical examination revealed the sinus tract (Fig 36- 7 a), and the preoperative radiograph showed a periapical radiolucency (Fig 36-7b). The diagnosis was previous pulpectomy and chronic apical periodontitis. Informed consent was obtained from the patient and her parents, local anesthetic was administered, and rubber dam was placed. Working length was determined with an electronic apex locator and a Gates Glidden drill #6 ( Fig 36-7c). The canal space was irrigated, and calcium hydroxide paste was placed as an inter-

Case 36-1 A 7-year-old boy was referred following a traumatic dental injury 2 months earlier. The maxillary right central incisor was severely intruded and repositioned surgically. A splint was applied, but no endodontic treatment was initiated. Two months later, a sinus tract developed at the buccal aspect (Fig 36-6a). Clinical testing revealed palpation and percussion sensitivity and a negative cold test. Radiographically, the apex was wide open with a periapical radiolucency (Fig 36-6b). The diagnosis was necrotic pulp and chronic apical periodontitis. Treatment options were discussed with the patient and his parents, and root canal treatment was selected as the treatment of choice. Local anesthesia was administered, and the tooth was isolated with rubber dam. After mechanical and chemical debridement (Fig 36-6c), an interappointment dressing of calcium hydroxide was applied (Fig 36-6d). At 1 month, the sinus tract was still present. The canal was further debrided and irrigated, and the calcium hydroxide was replaced. This time it was left in place for 3 months. At the third appointment, the sinus tract was healed (Fig 36-6e), and it was possible to obtain a dry canal. An extraradicular matrix of calcium sulfate was

appointment dressing (Fig 36-7 d). When the patient returned after 1 month, the sinus tract had healed (Fig 36- 7e). The canal was irrigated and dried, and a 5-mm apical plug of ProRoot MTA was applied using an MTA carrier. No matrix was placed in this case, and the postoperative radiograph showed extrusion of MTA into the periapical tissues (Fig 36-7f). A moist foam pellet was placed over the MTA, and the tooth was provisionalized. After 1 month, the patient was asymptomatic, and the sinus tract had not returned.

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Clinical Cases

Case 36-1

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Fig 36 - 6 (a ) A sinus tract developed after intrusion of the maxillary right central incisor, ( b ) Preoperative radiograph showing a radiolucency associated with the maxillary right central incisor and an immature root with an open apex . ( c) A low - speed instrument was used to determine the working length, (d ) An interappointment dressing of calcium hydroxide was placed, ( e ) Healed sinus tract . ( f ) An extraradicular matrix of calcium sulfate was placed. Note that it has the same radiopacity as dentin, (g and h ) An apical plug of MTA was placed with a Dovgan MTA carrier (Quality Aspirators) , (i ) Postoperative radiograph of the tooth restored with composite resin ( j and k ) At 1 year, the radiolucency had decreased in size, and the patient was asymptomatic . ( I to o ) At 3 and 7 years, the recall radiographs showed resolution of the radiolucency, and the clinical photograph showed a healthy tooth in full function. ,

The tooth was restored with a composite core material covered by a hybrid composite resin (Fig 36-7 g) . At that time, the author had not yet started routinely inserting fiber posts in immature teeth. Healing was uneventful, and at the 1-year recall, the radiographs showed no signs of apical pathosis (Fig 36-7 h). At the 2- and 6 - year recalls, the tooth had normal tissue architecture, and the

extruded MTA was partially resorbed (Figs 36-7i and 36-7 j). Clinically, the tooth displayed a gray discoloration (Figs 36-7 k and 36 -7 I), which was treated successfully with an internal bleaching procedure (Fig 36- 7 m). It was decided at that point to place three fiber posts (Figs 36-7n to 36- 7 p).

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Clinical Management of Teeth with Open Apices with the Apical Barrier Technique

Case 36-2

Fig 36- 7 (a ) The sinus tract was adjacent to the maxillary right lateral incisor but actually originated from the central incisor, (b) Preoperative radiograph showing an immature tooth with an open apex and a periapical radiolucency. (c) A Gates Glidden drill was used to determine the working length. (d) An intracanal dressing of calcium hydroxide was placed, (e) Healed sinus tract , (f ) An apical plug of MTA was placed without a matrix , resulting in extrusion of MTA into the periapical tissues, (g ) The remaining part of the canal and the access opening were restored with composite resin, (h) One-year recall radiograph showing no signs of pathosis. (i and j ) The 2 - and 6-year recall radiographs showed normal tissue architecture and partial resorption of the extruded MTA. ( k and I ) Clinical photographs at 2 and 6 years showed a gray discoloration of the tooth, (m) The discoloration improved after internal bleaching, (n to p) Three fiber posts and a composite core material were placed.

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Clinical Cases

Case 36-3

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radiograph showing an apical radio( ) Fig 36-8 (a) A sinus tract was present on the labial aspect of the maxillary right central incisor. b Preoperative and extruded root canal filling radiolucency a large showed scan a CBCT from lucency requiring endodontic retreatment , (c) A representative slice filling was extruded into the periapical material, (d and e) Three Thermafil carriers (Dentsply) were removed, and in the process some of the root canal instrument (G. Hartzell & Son). tissues, ( f ) The extruded filling was removed from the periapical tissues using a Terauchi gutta percha removal

The diagnosis was previous root canal treatment with chronic apical periodontitis. Treatment options were discussed with the patient and his parents, and endodontic retreatment was selected. At the first treatment session, the carrier-based canal filling was removed (Figs 36-8d to 36-8f), and a dressing of calcium hydroxide was placed in the canal (Fig 36- 8g). In addition, the splint was removed. At the second appointment 1 month later, the sinus tract had healed (Fig 36- 8h). The canal was irrigated and dried, and an apical plug of ERRM putty was placed (Figs 36- 8i and 36- 8j) using an MTA carrier and an endodontic condenser. A moist foam pellet was inserted on top of the putty, and the tooth was provisionalized. At the third appointment, it was verified that the apical plug of ERRM putty had fully set. To reinforce the immature root, two fiber posts were placed with a composite core material (Fig 36- 8k). The 2-year recall radiograph (Fig 36- 8I) shows a healthy, asymptomatic tooth in full function.

Case 36- 3 A 13 -year-old boy presented with a sinus tract associated with his maxillary right central incisor. Three years earlier, he had suffered a traumatic dental injury, and endodontic treatment had been performed. After 2 years, a sinus tract developed, and the tooth was retreated. The sinus tract persisted, and the patient was referred for evaluation and treatment. Two months before consultation, the patient fell from his bike and sustained a second dental injury. Because the tooth was mobile, it was splinted with composite to the adjacent teeth. The medical history was noncontributory. Clinical examination revealed a sinus tract on the labial aspect (Fig 36-8 a), and the splint was still in place after 2 months. Radiographically, the apex was wide open, and there was some extruded filling material and a slight radiolucency (Fig 36 - 8b). A cone beam computed tomography (CBCT) scan was ordered and revealed the presence of a large radiolucency associated with the tooth (Fig 36-8c).

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r Clinical Management of Teeth with Open Apices with the Apical Barrier Technique

Case 36-3 (cont )

Fig 36- 8 (cont ) (g ) A calcium hy droxide dressing was placed, (h) Healed sinus tract , ( i and j ) An apical plug of ERRM putty was placed, ( k ) The tooth was restored with two fiber posts and composite resin. (I ) Twoyear recall.

Clinical Tips

•The ERRM putty tends to dry out over time. A small

•To remove calcium hydroxide from a canal, alternate

•

amount of bioceramic sealer can be added to the putty to regain its normal consistency. Calcium sulfate is sold in two forms, one of which does not set Be sure that you have the hemihydrate form, as the anhydrous form does not set. Discoloration from internal placement of MTA can of •

17% ethylenediaminetetraacetic acid (EDTA) and 5% sodium hypochlorite. Activate them with sonic or ultrasonic energy. To • get the proper consistency with Biodentine, the liquid must be measured very precisely. a small amount of EndoSequence sealer on the Apply • tip of the instrument used to condense ERRM putty to prevent the putty from sticking.

.

be resolved with internal bleaching with sodium perborate.

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References 9. Lovato KF, Sedgley CM. Antibacterial activity of EndoSequence Root Repair Material and ProRoot MTA against clinical isolates of Enterococcus faecalis. J Endod 2011;37:15421546. 10. Leal F, De-Deus G, Brandao C, Luna A, Souza E, Fidel S. Similar sealability between bioceramic putty ready- to-use repair cement and white MTA . Braz Dent J 2013;24:362-366. 11. Alhadainy HA, Abdalla Al. Artificial floor technique used for the repair of furcation perforations: A microleakage study. J Endod 1998;24:33-35. 12. Pecora G, Andreana S, Margarone JE 3rd, Covani U, Sottosanti JS. Bone regeneration with a calcium sulfate barrier. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1997;84:424-429. 13. Yoshikawa G, Murashima Y, Wadachi R, Sawada N, Suda H. Guided bone regeneration (GBR) using membranes and calcium sulphate after apicectomy: A comparative histomorphometrical study. Int Endod J 2002;35:255-263. 14. Pietrzak WS, Ronk R. Calcium sulfate bone void filler: A re view and a look ahead. J Craniofac Surg 2000;11:327-333. 15. Desai S, Chandler N. The restoration of permanent immature anterior teeth, root filled using MTA: A review. J Dent 2009;37:652-657. 16. Cauwels RG, Lassila LV, Martens LC, Vallittu PK, Verbeeck RM. Fracture resistance of endodontically restored, weakened incisors. Dent Traumatol 2014;30:348-355. 17. Brito-Junior M, Pereira RD, Verissimo C, et al. Fracture resistance and stress distribution of simulated immature teeth after apexification with mineral trioxide aggregate. Int Endod J 2014;47:958-966. 18. Dikbas I, Tanalp J, Koksal T, Yalmz A, GungorT. Investigation of the effect of different prefabricated intracanal posts on fracture resistance of simulated immature teeth. Dent Traumatol 2014;30:49-54.

References 1. Sheehy EC, Roberts GJ. Use of calcium hydroxide for apical barrier formation and healing in non-vital immature perma nent teeth: A review. Br Dent J 1997;183:241-246. 2. Yassen GH, Platt JA. The effect of nonsetting calcium hydroxide on root fracture and mechanical properties of radicular dentine: A systematic review. Int Endod J 2013;46: 112-118. 3. Parirokh M, Torabinejad M. Mineral trioxide aggregate: A comprehensive literature review—Part III: Clinical applica tions, drawbacks, and mechanism of action. J Endod 2010; 36:400-413. 4. Parirokh M, Torabinejad M. Mineral trioxide aggregate: A comprehensive literature review—Part I: Chemical, physical, and antibacterial properties. J Endod 2010;36:16-27. 5. Ma J, Shen Y, Stojicic S, Haapasalo M. Biocompatibility of two novel root repair materials. J Endod 2011;37:793—798. 6. Attik GN, Villat C, Hallay F, et al . In vitro biocompatibility of a dentine substitute cement on human MG63 osteoblasts cells: Biodentine versus MTA ® [epub ahead of print 12 February 2014]. Int Endod J doi:10.1111/iej.12261. 7. Shokouhinejad N, Nekoofar MH, Razmi H, et al. Bioactivity of EndoSequence root repair material and bioaggregate. Int Endod J 2012;45:1127-1134. 8. Rajasekharan S, Martens LC, Cauwels RG, Verbeeck RM. Bio-

dentine material characteristics and clinical applications: A review of the literature. Eur Arch Paediatr Dent 2014;15: 147-158.

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CHAPTER

Marga Ree, DDS, MSC

When pulp vitality is lost in an immature permanent tooth, the result is a tooth with thin dentin walls that is prone to fracture. In addition, the affected tooth is likely to have a poor crown-to-root ratio. Therefore, it is highly desirable to maintain pulpal vitality whenever possible to allow continued root development and strengthening. The requirements for successful vital pulp therapy are teeth with minimal or reversible pulpitis, bleeding that can be controlled, a biocompatible/bioactive pulp-capping material, and the creation of a good external seal. The primary materials used for direct pulp caps in recent years have been calcium hydroxide, the original material of choice, and mineral trioxide aggregate (MTA), the more recent material of choice. MTA is part of a class of materials known as bioceramics. Bioceramics are inorganic, nonmetallic, biocompatible materials that have similar mechanical properties as the hard tissues they are replacing or repairing. They are chemically stable and noncorrosive, and they interact well with organic tissue. Several new bioceramic materials have been introduced in recent years. MTA is sometimes described in endodontics as a first-generation bioactive material. It has many desirable properties, including excellent biocompatibility, good sealing characteristics, and antimicrobial properties.1 It also has some disadvantages: The initial setting time is at least 3 hours, it is not easy to manipulate, and it is hard to remove after it sets.1'2 Clinically, both gray and white MTA stain dentin, presumably due to the heavy metal content of the material or the inclusion of blood pigment during setting.3 4 Although MTA has been used for a number of years as the first choice for vital pulp therapy,5-7 the staining of dentin, particularly in anterior teeth, is problematic. Bioceramic materials used in endodontics can be categorized by composition, setting mechanism, and consistency. There are sealers and pastes, developed for use with gutta-percha, and putties, designed for use as the sole material, comparable with MTA. Biodentine (Septodont) is calcium silicate cement that was developed as a dentin substitute for deep cavities. Biodentine is comparable with MTA in that it is biocompatible, bioactive when in contact with vital tissues, and suitable to be used

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Clinical Cases as a pulp-capping agent.8 10 It has a higher compressive strength than MTA 10 and can be applied in bulk on dentin without any conditioning.11*12 The material sets in 12 minutes and can withstand deterioration when used as a temporary filling for up to 6 months.13 The other primary bioceramic material that can be used for vital pulp therapy is EndoSequence Root Repair Material (Brasseler),14 which is available in a paste and a putty form. In particular, the fast-setting putty form is convenient as pulp - capping material. The newer bioceramic materials have several advantages over MTA. They have better clinical handling properties and do not stain dentin like white and gray MTA.3'4 15-20

6. Avoid formation of a blood clot, because this may impair healing. 7. Once hemostasis is obtained, place MTA, Biodentine, or Root Repair Material putty against the pulp

"

.

stump

8. Place a moist cotton pellet, and then insert a provisional restoration. 9. At the second visit, re-enter the tooth and confirm that the MTA, Biodentine, or Root Repair Material putty has set. Restore the tooth with a bonded composite resin restoration.

*

Clinical Cases

Partial Versus Full Pulpotomy

Case 37-1

The goal of a pulpotomy is to remove inflamed pulp tissue to the level of healthy tissue. A " capping" agent is then placed to promote healing at the amputation site and allow continuation of root formation (apexogenesis). A partial or Cvek pulpotomy is performed most

An 8 -year-old boy was referred following a traumatic dental injury 2 months earlier. A radiolucency developed at the apex of the maxillary left central incisor, and it was tender to touch (Fig 37 -1 a). Clinical examination detected palpation and percussion sensitivity. A cold test was negative. The diagnosis was necrotic pulp and acute apical periodontitis. Informed consent was obtained from the patient and his parents, local anesthesia was administered, and the tooth was isolated with rubber dam. After the access cavity was prepared, vital pulp tissue was visible in the coronal part of the root canal (Fig 37-1b), and it was obvious that the pulpal diagnosis was incorrect. The diagnosis was changed to reversible pulpitis, and a partial pulpotomy was performed (Fig 37-1 c). A cotton pellet soaked in 5% sodium hypochlorite was applied to the pulp stump with moderate pressure (Fig 37-1 d). After 5 minutes, the bleeding stopped (Fig 37 1e). White MTA was applied over the pulp with an MTA carrier to a thick ness of approximately 3 mm (Figs 37-1f and 37-1g). A moist foam pellet was applied on top of the MTA, and the tooth was provisionalized (Fig 37-1h). After 1 week, the patient returned for a definitive composite restoration (Figs 37-1i to 37-1k). At the 6-month recall, a cold test elicited a positive response. The patient was asymptomatic during that period, and the root exhibited continued maturation (Fig 37- 11). Radiographic examination after 1, 2, and 4 years revealed apical maturation and thickening of the root walls (Figs 37 -1m to 37-1o). The tooth continued to respond positively to cold tests. Clinical examination revealed a slight gray discoloration in the cervical part of the tooth due to the MTA (Fig 37-1p). The option of internal beaching was discussed with the patient and his parents, but they declined.

commonly with complicated crown fractures in immature anterior teeth A full pulpotomy (to the orifice level) is most often performed in multirooted immature teeth,

.

when the pulp is exposed during caries removal.

Clinical Technique Vital pulp therapy is reserved for teeth with no history of spontaneous pain, no sensitivity to percussion, no swelling, and no radiographic signs of pulpal necrosis Asep sis is paramount. Rubber dam should always be used. The clinical protocol for vital pulp therapy is as follows:

.

-

1. Disinfect the exposure site with a mild disinfectant, such as chlorhexidine. 2. Use an abrasive diamond bur in a high-speed handpiece with generous water spray to remove the superficial pulp tissue and create the least amount of damage to the underlying tissue. 3. Wash the cavity preparation with sterile saline to remove all debris. 4. Remove the excess liquid with suction and blot the tissue with a moist cotton pellet. Do not air- dry, because this will cause desiccation and additional tis-

.

sue damage

5. Use a sterile cotton pellet moistened with sodium hypochlorite or chlorhexidine to obtain hemostasis. Place dry cotton pellets over the moist cotton pellets and exert slight pressure. Hemostasis should be obtained in this manner within a few minutes.

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Vital Pulp Therapy in Immature Teeth

Fig 37- 1 (a ) Preoperative radiograph of maxillary left central incisor showing a radiolucency and an immature root with an open apex, (b) Upon entry, vital pulp tissue became visible, (c ) A partial pulpotomy was carried out with a diamond bur in a high- speed handpiece, (d ) A cotton pellet soaked in 5% NaOCI was applied to the pulp stump to obtain hemostasis, (e) After a couple of minutes, the bleeding had stopped, which is indicative of healthy pulp tissue, ( f and g ) White MTA was used as a pulp- capping material, ( h ) A moist foam pellet was introduced, and the tooth was temporized. ( i ) The MTA had set hard, (j ) The enamel and dentin were conditioned with acid-etching, primer, and bonding, (k ) Postoperative radiograph showing the pulp-capped tooth restored with a composite resin. (I to o ) At 6 months and 1, 2, and 4 years, respectively, the patient was asymptomatic and the recall radiographs showed continued root development , ( p) Clinical picture showing signs of grey discoloration in the maxillary left central incisor.

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Clinical Cases

Case 37-2

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an open apex and a complicated crown fracture. Fig 37- 2 (a ) Preoperative radiograph of maxillary left central incisor showing an immature tooth with , (c ) After a partial pulpotomy was carried out , a cotton pellet incisor central left maxillary the in fracture crown complicated a showing (b) Clinical picture picture showing the hemorrhage was controlled, ( e ) Biodentine , ( ) soaked in 5 % NaOCI was applied to the pulp stump to stop the bleeding d Clinical , showing a material with moderate radiopacity. ( g ) , ( f ) Postoperative radiograph of the pulp cap with Biodentine material capping pulp a as was used to obtain a dry field and expose the subgingival sulcus the into packed was cord ) ( retraction A h . out After 1 week , the Biodentine had not washed resin, (j ) Clinical picture of the restoration , ( i ) Postoperative radiograph showing the tooth restored with composite site fracture palatal the of margin , ( k and I ) Recall radiographs at 6 and 12 months, showing continued site labial the at composite a microfilled with layered of composite core material root formation.

pellet soaked in 5% sodium hypochlorite was applied to the pulp stump with moderate pressure (Fig 37 -2c). After 5 minutes, the bleeding stopped (Fig 37 -2d). Bio dentine was applied over the pulp with an MTA carrier to a thickness of approximately 3 mm (Figs 37 - 2e and 37-2f). The material set in approximately 15 minutes and was used as a provisional restoration. This is an advantage of Biodentine over MTA and makes it the author's preferred material for this situation. The patient returned after 1 week and was asymptomatic. The Biodentine was fully set and intact (Fig 37-2g). A gingivectomy was performed, and retraction cord was packed into the sulcus (Fig 37-2h). The tooth was built up with composite, shaped, and cut back so that a more esthetic microfilled composite could be layered on the

Case 37 -2 A 7 -year- old girl presented with sensitivity to hot and cold following a traumatic dental injury to her maxillary left central incisor 3 days earlier. Clinical examination revealed a crown fracture and a small pulp exposure (Fig 37-2b). Radiographically, it had an open apex and no periapical pathosis (Fig 37-2a). The diagnosis was a complicated crown fracture with reversible pulpitis. Treatment options were discussed with the patient and her parents, and a partial pulpotomy was selected as the treatment of choice. Local anesthesia was administered, and a partial pulpotomy was performed. It was not possible to apply rubber dam, but a clean, dry field was maintained throughout the procedure. A cotton

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ES

Vital Pulp Therapy in Immature Teeth

Case 37-3

Fig 37- 3 (a ) Preoperative radiograph of mandibular right first molar showing an insufficient restoration of composite resin and immature roots with open apices, ( b ) Clinical picture showing a pulp exposure under the composite restoration in the mandibular right first molar (c ) A pulp polyp was present, (d ) After the pulp polyp was removed, hemostasis was obtained, (e ) A composite buildup was placed before a full pulpotomy was accomplished (f ) A moist cotton pellet with 5% NaOCI was applied against the amputated pulp (g ) Clinical picture showing the hemorrhage was controlled, (h and i ) White MTA was used as a pulp-capping material. ( j ) MTA had set hard, ( k ) Postoperative radiograph of the pulpotomy with MTA and an adhesive build-up of composite resin. ( I to n ) Recall radiographs at 1.5, 2.5, and 6 years showing a normal tissue architecture and apical maturation and thickening of the root walls. ,

,

,

facial surface (Figs 37-2i and 37-2j). Recalls at 6 months (Fig 37 - 2k) and 12 months (Fig 37 -2I) showed a healthy tooth in full function with continuing root development.

stasis was obtained (Fig 37-3d), it was decided to place a resin composite buildup before performing a full pulpotomy to provide better isolation and make provisional restoration easier. An access opening was prepared through the buildup, the coronal pulp was removed, and a moist cotton pellet soaked in 5% sodium hypochlorite was applied to the radicular pulp in the orifices with moderate pressure (Figs 37-3 e and 37-3f). After a few minutes, the bleeding stopped (Fig 37-3g), and white MTA was applied over the pulp with an MTA carrier to a thickness of approximately 3 mm (Fig 37-3h). A moist cotton pellet was placed over the MTA, and a provisional restoration was placed (Fig 37 -3i). At the second visit 1 month later, it was verified that the MTA had set hard (Fig 37 -3j), and the tooth was restored with an adhesive composite restoration (Fig 37 - 3k). Recalls at 1.5, 2.5, and 6 years showed apical maturation and thickening of the root walls (Figs 37-3I to 37-3n). The patient remained asymptomatic, and the tooth responded positively to electric pulp testing.

Case 37 -3 An 11-year-old girl was referred after her dentist exposed the pulp when excavating caries in her mandibular right first molar. At the time of consultation, the patient was asymptomatic. Clinical examination revealed an inadequate composite restoration. Radiographically, the tooth had open apices and no periapical pathosis (Fig 37 - 3 a) . The diagnosis was a pulp exposure with re-

versible pulpitis. Treatment options were discussed with the patient and her parents, and a full pulpotomy was selected as the treatment of choice. At the first treatment session, rubber dam was placed and the composite filling was removed, revealing a pulp polyp (Figs 37 -3b and 37-3c). The polyp was removed with a new high-speed diamond bur. After hemo-

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References 6. Eskandarizadeh A, Shahpasandzadeh MH, Shahpasandza deh M, Torabi M, Parirokh M. A comparative study on dental pulp response to calcium hydroxide, white and grey mineral trioxide aggregate as pulp capping agents. J Conserv Dent 2011;14: 351-355. 7. Caprioglio A, Conti V, Caprioglio C, Caprioglio D. A longterm retrospective clinical study on MTA pulpotomies in immature permanent incisors with complicated crown fractures. Eur J Paediatr Dent 2014;15:29-34. 8. Shayegan A, Jurysta C, Atash R, Petein M, Abbeele AV. Biodentine used as a pulp-capping agent in primary pig teeth. Pediatr Dent 2012;34:e202-e208. 9. Nowicka A, Lipski M, Parafiniuk M, et al. Response of human dental pulp capped with biodentine and mineral trioxide aggregate. J Endod 2013;39:743-747. 10. Natale LC, Rodrigues MC, Xavier TA, Simoes A, de Souza DN, Braga RR. Ion release and mechanical properties of calcium silicate and calcium hydroxide materials used for pulp capping [ epub ahead of print 20 March 2014]. Int Endod J doi:10.1111 /iej/ 12281. 11. Laurent P, Camps J, De Meo M, Dejou J, About I. Induction of specific cell responses to a Ca3 Si05-based posterior restorative material. Dent Mater 2008;24:1486-1494. 12. Raskin A, Eschrich G, Dejou J, About I. In vitro microleakage of Biodentine as a dentin substitute compared to Fuji II LC in cervical lining restorations. J Adhes Dent 2012;14:535-542. 13. Koubi G, Colon P, Franquin JC, et al. Clinical evaluation of the performance and safety of a new dentine substitute, Biodentine, in the restoration of posterior teeth: A prospective study. Clin Oral Investig 2013;17:243-249. 14. Azimi S, Fazlyab M, Sadri D, Saghiri MA, Khosravanifard B, Asgary S. Comparison of pulp response to mineral trioxide aggregate and a bioceramic paste in partial pulpotomy of sound human premolars: A randomized controlled trial. Int Endod J 2014;47:873-881. 15. Parirokh M, Torabinejad M. Mineral trioxide aggregate: A comprehensive literature review—Part III: Clinical applica tions, drawbacks, and mechanism of action. J Endod 2010;36:400-413. 16. Boutsioukis C, Noula G, Lambrianidis T. Ex vivo study of the efficiency of two techniques for the removal of mineral trioxide aggregate used as a root canal filling material. J Endod 2008;34:1239-1242. 17. Jang JH, Kang M, Ahn S, et al. Tooth discoloration after the use of new pozzolan cement (Endocem) and mineral trioxide aggregate and the effects of internal bleaching. J Endod 2013;39:1598-1602. 18. Maroto M, Barberia E, Vera V, Garda -Godoy F. Dentin bridge formation after white mineral trioxide aggregate (white MTA) pulpotomies in primary molars. Am J Dent 2006;19:7579. 19. Percinoto C, de Castro AM, Pinto LM. Clinical and radiographic evaluation of pulpotomies employing calcium hy droxide and trioxide mineral aggregate. Gen Dent 2006;54:258-261. 20. Jacobovitz M, de Lima RK. Treatment of inflammatory internal root resorption with mineral trioxide aggregate: A case report. Int Endod J 2008;41:905-912.

Clinical Tips •For a partial pulpotomy, if moderate pressure with a

moist cotton pellet does not result in a nonbleeding pulp stump after 5 minutes, repeat the procedure. If excessive bleeding continues, extend the preparation further apically. •The use of astringents such as ferric sulfate (eg, Astringedent, Ultradent) is not recommended because it causes clotting, which can be detrimental to pulpal

health.

•When in doubt about the progress of root develop-

ment at recalls, take a radiograph of the contralateral tooth for comparison.

Summary Whenever possible, vitality should be preserved in an immature tooth with pulpal involvement. To be suc cessful, one must stop the bleeding, use a bioactive pulp-capping material, and create a bacteria-tight seal. Three cases have been presented in which MTA and Biodentine were used successfully for vital pulp therapy in immature teeth with pulpal involvement. In all cases, treatment provided elimination of symptoms and con tinuation of root formation.

References 1. Parirokh M, Torabinejad M. Mineral trioxide aggregate: A comprehensive literature review— Part I: Chemical, physical, and antibacterial properties. J Endod 2010;36:16-27. 2. Parirokh M, Torabinejad M. Mineral trioxide aggregate: A comprehensive literature review—Part II: Leakage and biocompatibility investigations. J Endod 2010;36:190-202. 3. Belobrov I, Parashos P. Treatment of tooth discoloration after the use of white mineral trioxide aggregate. J Endod 2011;

37:1017-1020. 4. Akbari M, Rouhani A, Samiee S, Jafarzadeh H. Effect of dentin bonding agent on the prevention of tooth discoloration produced by mineral trioxide aggregate. Int J Dent 2012;

2012:563203. 5. Hilton TJ, Ferracane JL, Mancl L; Northwest Practice-based Research Collaborative in Evidence-based Dentistry (NWP). Comparison of CaOH with MTA for direct pulp capping: A PBRN randomized clinical trial. J Dent Res 2013;92(7 suppl) :16S-22 S.

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CHAPTER

Scott A. Martin, DDS

This chapter was written in honor of the late Dr Ben Schein, who shared knowledge freely without asking for anything in return other than interesting conversation. Decompression is a surgical method of managing large periapical lesions that is more conservative (less invasive) than traditional methods of flap surgery and enucleation. Most teeth associated with large radiolucencies at the apex have necrotic pulps or previous root canal treatment and are therefore amenable to traditional root canal treatment. Occasionally, these lesions require surgery to achieve complete healing. When a large radiolucency is present, surgical intervention can cause devitalization of adjacent teeth or damage to other structures. Decompression is a procedure that can aid the healing process with minimal morbidity. It can result in complete healing or at least reduce the lesion to a size at which surgery will not affect the other teeth or adjacent structures. The prevalence of periapical cysts is about 15%, based on serial sectioning of lesions removed in their entirety.1 Of this number, 9% were “ true" cysts (completely lined with epithelium), and 6% were “ pocket " cysts, in which the cyst cavity was open to the root canal space. The pathogenesis of cysts is not well understood. The first step in the process is pulp infection and necrosis, with subsequent periradicular inflammation and development of a granuloma. Some granulomas develop into cysts, and this development occurs in stages. In the first stage, epithelial rests of Malassez proliferate. Second, a cavity develops that is lined by the epithelium from the proliferating cell rests. Over time, the cavity enlarges,2 which is thought to result from osmotic pressure and the interactions of proinflammatory cytokines with each other as well as with the host cells. It is a complex and poorly understood process, but relieving the intracystic pressure and diluting the inflammatory mediators with irrigation are thought to explain the efficacy of the decompression procedure.

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Decompression

Fig 38- 1 (a ) This 13- year- old boy presented with a canine space swelling and large periapical radiolucency that originated from the left lateral incisor, which contained a dens in dente. (b to e) A cone beam computed tomography scan showed that there was minimal labial and palatal bone and that the lesion appeared to penetrate through the floor of the nose. This complicated things if surgery became nec essary. ( f to h ) Nonsurgical root canal treatment was initiated with dual-access preparations. Calcium hydroxide was placed in the canals. ( i ) Radiograph at 1 month, ( j ) Radiograph at 3 months. Note how much bone regeneration was evident . The canals were obturated, and the tooth was restored at 5 months, ( k ) Radiograph at 6-month recall. (I ) Radiograph at 18-month recall. (Courtesy of Dr Rick Schwartz, San Antonio, Texas.)

Most lesions of endodontic origin

—even large lesions—

the German dental literature.3 A tube is placed through the mucosa and bone into the pathologic bone cavity and left in place for several weeks to allow "decompression." The lumen in the tube allows the patient to irrigate the bone cavity daily. Decompression is a minor surgical procedure with minimal morbidity. The author could not find any references in the literature describing significant complications associated with decompression.

usually be treated nonsurgically, so conventional root canal therapy is the first step, and decompression is considered only if the lesion is not resolving. The author generally does not complete the treatment of teeth with large radiolucencies until there is evidence of bone healing. This approach takes 3 to 6 months, with periodic changes of the calcium hydroxide dressing (Fig 38-1). Cyst decompression dates back to the turn of the last century when Partsch first described the operation in can

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EE

Decompression

Fig 38-2 (a) An intraoral impression mixing tip can be modified and used for decompression, (b) An opening is made into the cyst lumen through the mucosa , (c ) The mixing tip is inserted after its length is adjusted, (d ) The flange is shortened until it fits snugly against the mucosa. (Courtesy of Dr Marga Ree, Purmerend, The Netherlands.)

7. Remove and reinsert the drain in 2 weeks. The soft tissue will heal against the tube, which can be removed and replaced easily. As with implant abutments, the soft tissue will begin to collapse when the drain is removed, so do not delay replacement more than a few minutes. With a latex catheter material, one could simply use the next smaller size if the original drain does not reseat. With a tapered impression tip, apply light pressure for a few minutes to allow the drain to fully reseat. . 8 Check the patient at 1 week, 2 weeks, 1 month, and 6 weeks, at which time the drain can usually be removed for good. 9. As the bone heals, the drain is sometimes pushed out and must be shortened and reinserted.

Materials A variety of materials can be used as drains. For example, a plastic impression tip with a flange can be modified to serve as the tube and can be sutured in place. The flange rests against the mucosa and prevents the patient from accidentally pushing it into the bone cavity during daily irrigation (Fig 38 - 2). It is an advantage if the material is radiopaque. Latex catheter material or polyethylene intravenous tubing (Schein Medical) can also be used. Both are inexpensive and can be obtained in several different sizes. Sizes 8, 10, and 12Fr are ap propriate sizes to keep in stock. One end of the tube is heated, and the tip is pressed against a glass slab to create a flange.

Time frames for decompression are empirical because there are no controlled clinical studies to provide guidance. The shortest time frame found in the literature is 2 days for decompression of a cyst related to a maxillary molar (confirmed by biopsy),4 while oral surgeons sometimes leave drains in place for several months for patients with very large lesions.

Clinical Technique The clinical protocol for decompression is as follows: 1. Make a 1- to 1.5 -cm vertical incision through the mucosa. The incision should be placed between root eminences. 2. If a biopsy is desired, a sample of tissue can be taken at this time. However, in most cases, enucleation of the entire lesion needs to be performed to make an accurate diagnosis; this requires reflection of a full

Case Report A healthy 13-year-old boy presented with a labial sinus

tract stoma in the mucosa

above the maxillary left lateral incisor. Radiographs revealed an extensive radiolucency centered over the apex of this tooth. However, the sinus tract traced to the adjacent central incisor (Fig 38 - 3 a), which was nonresponsive to cold and electrical stimulation. All other maxillary anterior teeth responded normally to pulp sensitivity testing. Access was made into the central incisor, and the pulp was necrotic. The canal space was debrided and irrigated, and a Vitapex calcium

flap. 3. Make entry into the bone cavity. This can usually be accomplished with the scalpel tip or a blunt instrument through soft tissue, but sometimes it is necessary to make a window in the bone with a bur. Drainage of pus or straw -colored fluid is often

encountered. 4. Flush the bone cavity with sterile saline to reduce the bacterial load as well as the levels of inflammatory

hydroxide dressing (Diadent Group International) was placed (Fig 38-3b). One month later, the sinus tract was healed and treatment was completed (Fig 38-3c). At the 3 - month recall, the sinus tract had returned, and the decision was made to attempt decompression. A 1-cm incision was made in the mucosa between the roots of the central and lateral incisors, and the infected bone

mediators. 5. Insert the cannula (drain) into the bone cavity and cut it to length so that it extends completely to depth with the flange against the mucosa. 6. Apply one or two sutures to secure the drain to the mucosa during the healing phase.

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References

Fig 38- 3 (a ) Even though the radiolucency appeared to be centered on the lateral incisor, the sinus tract traced to the central incisor. The central incisor was the only tooth that was nonresponsive to pulp testing, (b) Vitapex was placed in the canal after shaping and irrigation, (c) Endodontic treatment was completed about a month later, (d ) A size 10Fr latex urologic catheter is shown 2 weeks after placement, (e) At 6 weeks, the drain was removed, ( f ) At 8 weeks, there was nearly complete healing of the mucosa, (g and h) The bone appeared to be completely healed at the 18-month recall, ( i ) Ten -year recall.

cavity was flushed with sterile saline. A 2-cm-long size 10Fr radiopaque latex catheter was placed to depth, and two sutures were placed to stabilize it. The patient was instructed to irrigate daily with chlorhexidene 0.12%. At 2 weeks, soft tissue healing was excellent (Fig 38-3d). The drain was removed after 6 weeks (Fig 38- 3e), and healing of the mucosa was evident 2 weeks later (Fig 38-3f). At 18 months, bone healing was nearly complete (Figs 38-3g and 38-3h). Ten years later, the bony architecture was normal on radiographs (Fig 38-3i), and the adjacent teeth responded normally to pulp testing.

the need for more extensive surgical procedures or at least make them easier to perform while reducing the chance of devitalizing adjacent teeth or affecting other anatomical structures. If decompression proves to be ineffective, flap, curettage, and biopsy procedures can be performed.

References 1. Nair PN. New perspectives on radicular cysts: Do they heal? Int Endod J 1998;31:155-160. 2. Nair PN. Apical periodontitis: A dynamic encounter between root canal infection and host response. Periodontol 2000 1997;13:121-148. 3. Partsch C. Uber Kiefercysten. Dtsch Monatsschr Zahnheilkd 1892;10:271. 4. Loushine RJ, Weller RN, Bellizzi R, Kulild JC. A 2-day decompression: A case report of a maxillary first molar. J Endod 1991;17:85-87.

Conclusion Decompression is a procedure that is occasionally indicated when nonsurgical treatment of a large radiolucency is unsuccessful. It is a fairly simple surgical procedure with low morbidity that uses inexpensive and readily available materials and that has a low occurrence of untoward outcomes. In some cases, it will obviate

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CHAPTER

Ivan N. Vyuchnov, DDS, MSC

Suturing Under the

Many teeth with failing root canal treatment are amenable to retreatment, but some teeth contain separated files, blockages, ledges, perforations, or other obstacles that interfere with retreatment. For these teeth, surgical intervention may be an option. Apical surgery requires skills that include incision and flap elevation, apical root resection, retrograde preparation, and obturation. These pro cedures are best performed under a dental operating microscope, a skill set that must be learned like any other. Somewhat less intuitive is suturing under a microscope, and not many clinicians have developed this skill set. Suturing itself is a surgical procedure, and trauma is caused by the needle piercing the tissue. The number of sutures and the size and properties of the needle and suture materials influence healing. The fine sutures that are usually used under the microscope, such as 7 -0, 8-0, and 9-0, will not impede healing. The function of sutures is to position and stabilize the flap during wound healing and provide initial hemostasis. The sutures should secure the flap without imposing needless traction. A microscopic approach provides clear visualization, which aids in precise work and passive wound

closure. This chapter provides an overview of and specific techniques for suturing under a microscope. It discusses how microscopic suturing techniques can provide " kinder " soft tissue management, resulting in reduced morbidity and fewer surgical complications It focuses on the ergonomics of working with a chairside assistant for a smooth, efficient workflow with less stress.

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Armamentarium

Fig 39- 2 (a) Poor tissue approximation in tension, with coarse sutures. (b) Brutal soft tissue management resulted in scarred tissue.

Fig 39-1 (a ) Postoperative view of passive wound closure with 7-0 Prolene sutures (Ethicon). (b ) Recall at 1.5 years shows minimal recession and scarring of the wound.

b

c

Fig 39- 3 (a) Castroviejo type needle holder with a one-click locking device, (b) Close-up view of the locking device, (c) The diamond coating of the tips secures the needle, (d) A curved tip can access any location.

Advantages of Microsuturing

Armamentarium

Compare the patients who received apical surgery in Figs 39-1 and 39 - 2. In Fig 39-1, the surgical flap was passively repositioned and gently sutured with fine sutures. In Fig 39 - 2, the flap was repositioned poorly and sutured under tension with course sutures. Look at the difference in soft tissue healing. Which patient do you suppose had the more comfortable postoperative course? The microsurgery process is generally performed between 2 x and 6 x magnification. Higher magnifications can be used with very fine suture materials. Traditional surgery that is viewed under the microscope often re veals coarse surgical manipulations and poor primary closure with gross crushing and tearing of the tissues. Direct vision provides resolution as low as about 0.2 mm. At this level of visual acuity, fine hand movements have precision of only about 1 mm. Physiologic tremor can further reduce precision. Under magnification, visual resolution and fine motor control are greatly improved. This contributes to precise incisions, flaps that are elevated with minimal damage, and precise primary wound closure that is without tension.

Microsurgical needle holder There are specific design requirements for microsurgical needle holders. The body of the instrument should be circular in cross section in order to allow for smooth rotational movements. For precision movements, microsurgical instruments must be approximately 15 cm in length. For an average-sized hand, this provides adequate length for an instrument held in a pen grip to rest in the web between the thumb and index finger. The needle holder should be light and easy to manipulate with a single movement of the hand and should lock in only one position, where it can be locked and unlocked with minimal force. The author prefers the Castroviejo type needle holder (Fig 39-3 a). It allows the clinician to grasp and catch the needle quickly using a single movement of the index finger and thumb to close and open the jaws. The locking device is located in the handgrip area (Fig 39-3b), which allows the operator to lock and unlock it with light forces and without repositioning the fingers. A diamond coating of the internal surface of the jaws (Fig 39-3c) provides a solid grip on the needle and prevents it from slipping or rotating. Straight or curved working tips are available, but the curved tip can be applied in all areas of the mouth (Fig 39-3d).

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Fig 39- 4 Anatomical tissue and needle forcep

Fig 39- 5 Suture scissors should be springloaded, have gently curved blades, and be light ly rounded at the tips. They should be fast and precise.

Fig 39-6 (a and b ) Round needles are generally only used with thin, fragile tissue.

Tissue forceps

suture sizes than traditional surgery. Therefore, suturing needles for microsurgery must be:

Tissue forceps are used to delicately hold (not pierce or crush) the tissue, to pass the needle between hands, and to tie knots (Fig 39-4). If the clinician is right-handed, the tissue forceps are generally held in the left hand. An efficient surgeon must be able to use both hands when performing surgery in general as well as when suturing.

•Stable in the needle holder

•Able to pass through the tissue with minimal trauma •Sharp

enough to penetrate the tissue with low resistance •Rigid enough to resist deformation Curved needles with the radius of % or V2 mm are most widely used in oral surgery because they require less room to maneuver in hard-to-reach areas

Suture scissors

.

Suture scissors should be spring-loaded, have gently curved blades, and be lightly rounded at the tips (Fig 39 -5). They should allow a single hand movement to cut the suture once the knot is tied.

The shape and thickness of the needle is selected based on the tissue biotype. The round- bodied or cy lindric needles (Fig 39 - 6) are better for thin biotype tis sues because they are less likely to cause tissue tearing than the traditional cutting or reversed cutting needles, which have sharp edges. Round needles have limited use and are generally not suitable for thick tissue bio types because they are not stable in the needle holder and rotate easily. This results in wasted movements and inefficient suturing.

Suturing needles The goals of microsurgery are minimal trauma to the flap, precise primary closure, and tension-free stabilization. This is accomplished with more sutures and smaller

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Armamentarium

^

Jap

ii Siilftl Fig 39- 7 (a and b ) Most suturing in oral surgery is done with reverse cutting, triangular tips.

Fig 39- 8 Fine to coarse suture materials used in oral surgery. From left to right: 7-0, 6-0, 5-0, 4-0.

Fig 39- 9 (a ) Close-up view of Prolene, a monofilament suture, (b) 5-0 Vicryl multifilament sutures (Ethicon) used in conventional surgery. Note the coarseness of the material.

absorbable versus nonabsorbable. The cross-sectional thickness of a suture is expressed in zeros. Finer suture materials have more zeros. A 3-0 suture (000) is finer than a 2-0 suture (00). In microsurgery the 6-0, 7-0, and 8-0 are generally the sutures of choice (Fig 39-8). Monofilament sutures are comprised of a single strand or thread, as opposed to multifilament sutures, which are woven or braided. Monofilaments produce less friction while passing through tissue and are less traumatic. Because there are no gaps in monofilaments, they are less prone to microbial colonization and wicking. However, monofilament sutures are more prone to untying, so they must be secured with multiple knots. They are also more prone to damage because of their single strand. The author works primarily with a 7 -0 monofilament nonabsorbable Prolene suture (Fig 39-9a), which meets all of the requirements needed for adequate flap closure, adaptation, security, and knot tying (blue suture in Fig 39- 8). A multifilament suture is shown in Fig 39-9b.

With thick tissue biotypes, a reverse cutting needle is preferred. It is triangular in shape with sharp edges (Fig 39-7), which reduces tearing while piercing the tissue. In addition, this geometry provides a stable base for the needle holder, which prevents rotation and allows a single movement to pass the needle through the tissue. This is an " aggressive " needle design, and care must be taken if the tissue biotype is thin; if tissue tearing occurs during the initial needle pass, the suture may tear the flap when the knot is tied.

Suturing material The ideal suture material is sterile, easy to handle, minimally reactive in tissue, resistant to tissue shrinkage, and secure when knotted. It must retain its strength until the wound heals sufficiently to withstand stress on its own. The clinical situation generally dictates the preferred suture material. Sutures are described in several different ways, including by material type, monofilament versus multifilament, and

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Suturing Under the Microscope

Fig 39-11 (a and b) OptraGate in action. It is an indispensable tool for the surgeon and the assistant when operating in the anterior.

Fig 39- 10 The author performing microsurgery. Note how relaxed and comfortable he and his assistant look with chairs that support their arms. Both have microscope oculars that allow them to focus on the surgical field.

Fig 39-12 The pen grip used most often by the

author.

Gripping the Instruments

Accessory instruments Microsurgeon's stool

How you grasp the instruments for microsurgery is somewhat different than for traditional surgery. The instrument grip influences precision and your ability to reach areas of difficult access.

The surgeon's arms should be supported by the armrests of the surgical stool, with the needle holder in one hand and the tissue forceps in the other. This special chair allows the surgeon to operate primarily with Class I and Class II movements (see chapter 1), making the surgery more efficient and precise and reducing the tension on the shoulders, arms, and hands of the operator (Fig 39-10).

Pen grip The pen grip (also referred to as a pencil or internal precision grip ) is the most common and widely used grip in microsurgery (Fig 39-12). It allows for fine, precise movements in the operating field. The pen grip must be mastered to perform microsurgery. The three-digit pen grip is the same grip as that used for writing. The thumb and index and middle fingers are used as a tripod. The instrument can be opened and closed with very fine control. The knuckles should be positioned away from the surgeon, so that the ulnar border of the hand, the wrist, and the elbow are well supported by the arms of the surgeon's chair. The middle finger should rest firmly and directly on either the working surface, supporting the hand, or indirectly on the ring finger. With the tripod formed by the fingers in the pen grip, the medial-side middle finger supports the instrument. The thumb and index finger are arranged on the

Assistant microscope binoculars Working with an assistant who is trained to work through assistant-side oculars (see Fig 39-10) is a huge benefit to a surgeon. Because the assistant has the same view of the magnified field of operation as the surgeon, he or she can be more efficient and precise in managing evacuation of blood and saliva, tissue retraction, instrument passing, and anticipating the needs of the surgeon. An accessory cheek retractor such as the OptraGate (Ivoclar Vivadent) (Fig 39-11) or OptiView (Kerr) can be useful when operating in the anterior part of the mouth. It provides hands-free retraction, allowing the doctor and the chairside assistant to focus on the area of the surgery.

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Clinical Considerations

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Fig 39-13 (a to c ) The motorcycle grip for passing the needle through the tissues in one smooth motion

Fig 39-14 (a and b) The eggbeater grip for ty ing the knot.

b

instrument in contact with the underlying middle finger. Any tremor resulting from the thumb or index finger is minimized by the support of the middle finger.

Eggbeater grip The eggbeater grip was designed for knot tying and utilizes a motion similar to that used to beat eggs in a bowl (Fig 39-14). The end of the needle holder is grabbed be tween three fingers: the index finger, the middle finger, and the thumb. The needle holder is placed parallel to the suture material and then rotated like an eggbeater to form and tie the knot.

Other grips The "motorcycle" and " eggbeater " grips are used for a suturing technique developed by Dr Gary Carr. These grips utilize the Castroviejo Gomel needle holder because it has concavities at the base of the jaws that are necessary for the motorcycle grip A special Castroviejo instrument with a longer area of exterior rough metal works best for the eggbeater grip.

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Clinical Considerations

Motorcycle grip

Tying knots

The motorcycle grip facilitates a motion like that used the engine of a motorcycle (Fig 39-13). With a single rotation of the wrist, the needle is passed through the tissue.

The author ties almost all suture knots with instruments. This is called the portiligature type of suturing. Once learned, this type of suturing is precise and efficient. As with any new skill, however, it requires practice. Raw chicken legs are very good for practicing microsuturing at the bench top. Besides suturing the skin and muscle, one can dissect out blood vessels, cut them, and then suture them back together with 7-0, 8-0, or even 10-0 sutures

to start

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EH Suturing Under the Microscope

Fig 39-15 (a to f ) The sequence for simple interrupted sutures, (g ) Clinical example with 7 -0 Prolene sutures.

Fig 39-16 (a to j ) The technique for mattress sutures, ( k ) The modified vertical mattress Gottlow suture is stabilizing the frenulum in situ, the area of severe muscle tension. (I ) Postoperative bleeding had occurred on the fifth day after surgery because the frenulum had been closed with interrupted sutures only. More stable mattress sutures would probably have prevented the dehiscence.

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Types of Sutures

Posture and position The surgeon must work from a position and posture that is relaxed and comfortable. To find this position, sit in your surgical chair at 12 o ' clock to the patient and po sition the microscope at a comfortable height and location with your arms on the armrests. Close your eyes and relax your shoulders, neck, and back. Sit upright, put your hands in a working position, and adjust the armrests to the most comfortable, relaxed position. This is the ideal ergonomic working position. Most of the surgical procedures in endodontic surgery are performed with the surgeon at 12 o'clock to the pa tient. Rotate the patient's head away from the working side. For example, if you are performing the surgical procedure in the maxillary left quadrant, rotate the pa tient 's head to the right.

-

The first step consists of passing the needle through the margin of the free flap from the outside inward. When the adjacent tissue is fixed, the needle should then pierce the fixed tissue from inside outward, maintaining the same penetration distance on both sides of the incision. The needle end of the suture is then twisted twice with the needle holder in a clockwise direction, making a loop. The end of the suture is grasped with the needle holder and pulled outward with tissue forceps to form the first knot. To secure the knot, additional knots are made in alternating counterclockwise and clockwise loops. The sequence for interrupted sutures is shown in Figs 39-15a to 39-15f, and a clinical example is shown in Fig 39-15g.

Vertical mattress Gottlow suture (modified vertical mattress) Vertical mattress sutures work well for flaps where strict stabilization or fixation is required. These areas are often in the esthetic zone with low frenulum attachments or high muscle tension and a high risk of flap disruption. This method of suturing allows the surgeon to suture two planes simultaneously. The first flap is pierced through the external mucosa inward at a distance of approximately 4 to 6 mm from the incision line. The needle pierces the underside of the second flap equidistant from the incision line. The needle is then turned perpendicular to the plane of the wound, and the tissue is pierced from outside inward at a distance of approximately 1.5 to 2.0 mm from the exit hole and at least 1.5 mm from the incision line. The needle then pierces the underside of the first flap close to the incision line, a loop is formed on the free side of the flap, the needle is passed through this loop, and the suture is tied. This technique secures the wound and compresses the incision line for tighter adaptation of the cut edges. This type of suture may be used where extra stabilization is needed due to muscle tension. The sequence for the mattress suture is shown in Figs 39-16a to 39-16j, and a clinical example is shown in Figs 39-16k and 39-161.

General rules for suturing

•The more precise the incision, the better the reapproximation of the flap.

•To prevent tearing of the tissue, the 2-mm suture rule should be used. There should be 2 mm of tissue be-

tween the incision line and the entry and exit points of the needle and 2 mm between consecutive stitches. • Knots should be placed over tissue, never over the incision line. •Sutures should be tension free. They should be pulled tight enough to bring the incised edges into contact without restricting blood supply. Remember: "Approximate, don't strangulate."

Types of Sutures Interrupted sutures Interrupted, vertical mattress sutures are most often used for mucoperiosteal surgery. They can be utilized with all flap designs and function independently. If one suture breaks or pulls free, the remaining sutures are not disturbed.

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» Suturing Under the Microscope

Fig 39-17 fa to e) The figure eight suture technique utilizes interrupted sutures to secure the flap and interdental papillae, (f ) The horizontal portion of the flap was secured with figure eight sutures.

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:

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Fig 39-18 fa) The needle holder and tissue forceps are grasped in a pen grip, (b) The needle penetrates the flap about 2 mm from the incision line and is passed through the incision and about 2 mm into the fixed tissue. The tissue forceps are used to secure the tissue during the needle pass, (c) The tissue forceps are used to grasp the needle and pull the suture through, (d) The needle holder and tissue forceps work in concert to loop the suture around the needle holder, which then grasps the free end of the suture (e) and creates the first tie in the knot ( f ).

brought between the teeth to the lingual or palatal side. Here the needle is " recaught " and rotated in order to pierce the papilla from the palatal side, brought between the proximal surfaces, and sutured with the tail that remains at the first area where the initial pierce was made (buccal or facial side).

Figure eight suture This type of suture may be used in the interproximal areas to stabilize the flap and secure the papillae (Fig 39-17). Figure eight sutures are used in between the proximal surfaces of the teeth. The initial pierce is made from the buccal or facial side through the papilla, then

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Clinical Technique Fig 39-19 A special Castroviejo Gomel needle holder that has a roughened metal finish almost to the end of the handle is used for the Carr suture technique.

The Carr suture technique

Clinical Technique

This technique incorporates only one hand and the needle holder, preferably the Castroviejo Gomel. The advantage of this technique, compared with the one described above, is that it allows the clinician to see the needle and the suturing material all within the field of vision and thus control the suturing process through the entire procedure. It also limits the chairside assistant 's duties to retraction and positioning of the tissues. A special Castroviejo Gomel needle holder is recommended with roughened metal to the end of the handle (Fig 39 -19). The steps of the Carr suture technique are as follows:

Once the surgical site is ready for closure, the flap should be gently massaged to a close approximation with the attached tissue. Keep in mind that the flap has proba-

bly shrunken slightly due to the period of elevation and reduced blood flow. If force must be used to reposition the flap margins correctly, a horizontal periosteal releasing incision at the base of the flap may be necessary. Sometimes slight elevation of the tissue adjacent to the flap facilitates a cleaner needle pass and prevents the tissue from tearing. The clinical technique for suturing a flap is as follows: 1. The needle holder and tissue forceps are held in a pen grip (Fig 39-18 a). 2. The assistant works through the assistant oculars to retract and control the tail of the suture, preventing it from touching surfaces that are not sterile and making it available to the surgeon for the ties. 3. The surgeon slightly retracts the flap with the tissue forceps and passes the needle through the flap and then through the tissue to which the flap is going to be sutured or approximated (Fig 39 -18b). 4. The surgeon grasps the needle with the tissue forceps and pulls the suture material through both tissue segments, leaving about 2 cm of the tail protruding from the reflected flap (Fig 39-18c). 5. The surgeon passes the needle to the chairside assistant, holds the tip of the tail with the tissue forceps, rotates the suture clockwise twice around the needle holder (Fig 39-18d), opens the jaws of the forceps and grasps the tip of the tail (Fig 39-18e), and then ties the knot (Fig 39-18f). 6. One or two additional ties, in alternating rotations,

1. The surgeon holds the needle holder in a motorcycle grip (Fig 39-20a). 2. The tissues are pierced, and the tip of the needle is caught with the needle holder in a pen grip (Fig 39-20b). 3. The surgeon lays his or her hand flat in the field of view, and the needle is placed on the palm at the base of the pinky finger, with a sharp tip toward the palm (Fig 39-20c). 4. The surgeon secures the needle with the pinky finger, the hand is rotated, and the needle holder is placed under and parallel to the suture (Fig 39- 20d). 5. The suture is then pinched with the thumb and index finger and pulled with a pinch-pull motion until the tail of the suture is visible in the field of vision and about 2 cm stick out of the tissue (Figs 39-20e to 39 -20g). 6. The needle holder is grasped with an eggbeater grip, the suture is twisted around it to create a loop (Fig 39-20h), the tail is grasped in the beaks (Fig 39 - 20i), and a knot is tied (Fig 39-20j). 7. The surgeon passes the needle holder to the assis-

are added on top of the original knot. 7. The assistant snips both parts of the suture and transfers the needle to the surgeon to start the next

tant, who

simultaneously grabs the needle holder and passes the scissors to the surgeon 8. The suture is cut.

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suture.

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Suturing Under the Microscope

Fig 39 - 20 (a ) In the Carr suture technique, a motorcycle grip is used to make the first needle pass in one motion, (b ) The needle holder is used in a pen grip to grasp the needle and pull it through the tissue. The needle is then placed on the edge of the surgeon’s palm (c) and grasped with the pinky finger (d ). The hand is then rotated, the suture is grasped between the thumb and pointer finger (e), and the suture is pulled through the tissue with a pinch- pull motion ( f and g ). The needle holder is rotated with an eggbeater motion ( h ), the loose end of the suture is grasped ( i ), and the first tie of the knot is complete ( j ).

Recommended Reading

Summary The best surgeons are masters of the basics, and nothing is more basic than suturing. This chapter discussed the armamentarium and principles of suturing under the dental operating microscope, which requires different ergonomics and skill sets than traditional suturing. Like many things in dentistry, suturing incorporates care, skill, and craftsmanship.

Dibart S, Karima M. Practical Periodontal Plastic Surgery. Ames, Iowa: Blackwell Munksgaard, 2006. Merino EM. Endodontic Microsurgery. London: Quintessence, 2009.

Shanelec D. Periodontal microsurgery. J Esthet Restor Dent 2003;15:402-407. Siervo S. Suturing Techniques in Oral Surgery. Milan: Quintessenza, 2008. Zoltan J. Cicatrix Optima. Budapest: Akademiai Kiado, 1974.

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CHAPTER

itchell H. Davich, DMD Marc Balson, DDS

Keys to Effective

The dentist 's profession enables him to see so many varied examples of humanity that his clinic sometimes resembles the backstage of a theater; where the performers, out of costume and minus —A A. Alswany 1 makeup, are no longer acting.

Effective Communication in the Endodontic Office The endodontic office setting presents unique challenges and opportunities for doctor-to- doctor and doctor-to-patient interactions. Successful endodontists know that the words they employ to communicate their ideas, feelings, and thoughts to their patients and referring dentists are equally as important as their diagnosis and execution of treatment procedures. Communication is an inexact art and science, and just as stories change each time they are told, patients can interpret communication from endodontists, general dentists, and dental support staff members a number of ways. Clear, effective communication between endodontists and their patients is a must to ensure that patients receive the best care possible and have a positive overall experience. This chapter presents protocols that have been developed over more than 65 years of combined experience in private practice, the scientific basis of which may be criticized and debated. It discusses various aspects of communication between the endodontist, referring doctor, and patient from introduction through postoperative care that is relevant to all parties involved in the referral process.

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Keys to Effective Communication

focus, recollection, and repetition. Paraphrasing (ie, using similar words and structure) and reflection (using one's own words and structure) can drastically alter the interpretation of statements by adding analysis and reasoning. In this way, the story may change every time it is told, depending on the perceptive and cognitive biases of storytellers and interpreters. Refraining from judgments based on personal interpretations creates a more patient-focused analysis, resulting in a positive, patient - centered outcome.

How to Make a Good First

Impression A patient 's first impression of a specialist is based on what he or she was told by the referring office. Patients trust their general dentist, and it is important for specialists to foster the same level of trust. Because the patient 's first interaction with the accepting office usually occurs via telephone, verbal communication is a fundamental step. The receptionist must be efficient and professional but also welcoming and sympathetic. Your receptionist should use phrases that reinforce what the patient should have heard from the referring office, such as, " We will take good care of you," and "Dr Jones is very gentle," as well as phrases like " We have worked with [ your dentist ] for many years. [ He or she ] is great, and we love seeing [ his or her ] patients," which can be helpful and comforting to the patient. During the telephone conversation and initial patient interview, it is important that discussions remain patient centered. Answers to three key questions should be

Clinical Examination Nonverbal communication is just as important as verbal communication. Start the clinical examination with a cancer screening, including gentle palpation of the soft tissues. This process should be pleasant, enabling the patient to start off with a positive experience. It sends two important messages: "This doctor is thorough," and "This doctor is gentle and is not going to hurt me."

obtained: 1. What brings you to the office today? 2. What do you think is the problem? 3. What do you think will fix this problem?

The Role of Communication in Diagnostic Outcomes Making a diagnosis requires an endodontist to integrate effective communication with probability and decision theory. Asking the wrong preoperative questions or not asking any questions at all can have a significant effect on diagnostic outcomes. The importance of asking the right questions is illustrated in the following examples. Patient A's referral letter reads as follows: " Our patient has been referred to your office for treatment of tooth no. 31." Viewing patient A's radiograph (Fig 40-1), there is a tendency to reduce the clinical complexity of the diagnosis and focus on the second molar (tooth no. 31) because the radiograph displays a periapical radio lucent finding. However, effortful communication elicited patient A's chief concern to be thermal sensitivity triggered by cold and lasting several seconds afterward, which eventually uncovered the first molar as the source of patient A's pain. Patient B was originally asymptomatic and underwent a routine crown preparation on the mandibular left second premolar (Fig 40- 2). Three weeks later, patient B developed heat sensitivity and was unable to chew on the left side. Under these circumstances, one might expect to be endodontically treating this second premolar, since it was recently prepared. However, carefully focused discussion and testing led to the discovery that the first molar was actually the offending tooth.

The First Appointment Completion of patient registration through a secure website is standard today. It demonstrates that your office is technologically advanced and runs efficiently. It provides the accepting office with the patient 's back ground information and necessary documentation before the first appointment, so all the patient needs to do is check in and provide a few electronic signatures. Hav ing a streamlined registration process is very impressive to most patients and engenders a feeling of confidence that they were referred to the right place. Prior to entering the operatory to meet the patient, the endodontist should review all relevant documentation about the patient, including patient information, medical history, referral notes, and radiographs. You want the patient 's first impression to be, "This doctor knows me, is well prepared, and did his or her homework." Because virtually every patient likes to discuss his or her medical history, discussion of the medical history is a great conversation starter after your initial introduction. Staff members who acquire verbal medical histories must be skilled in both active listening and speaking. Essential objectives of active listening are perception,

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Making Your Case Presentation

Fig 40- 2 Although the mandibular left second premolar was prepared for a crown, the first molar was actually the source of patient

Fig 40- 1 Although the radiograph suggests a problem with the mandibular right second molar, patient A’s pain was coming from the first molar.

B’s pain.

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Fig 40- 3 Custom-made visual aid for case presentation. (Courtesy of Dr Anthony L. Horalek, Raleigh, North Carolina.)

For the patient with preconceptions that interfere with rational decision making, the authors recommend that the endodontist use a four-step technique to circumvent these biases: ( 1 ) lead with the correct view; (2) show work in multiple formats while "thinking out loud"; (3J avoid defensiveness and hostility by reframing in an outsider's perspective; and (4) leave an open door for the patient to replace prior views while maintaining personal pride. Although biases may be difficult to overcome, this technique has proved to be highly reliable in counteracting them. Simultaneous documentation allows for immediate feedback via written or email report (Fig 40- 4). It is recommended that patients also receive copies of these reports, because correspondence serves as powerful confirmation and reinforcement tools. In these narratives, the unanswered question or problem that generated the referral and its solution should be addressed in transparent and straightforward language. The patient can then make an informed decision after being presented with choices and the best available option in the opinion of the endodontist. Informed consent constitutes the backbone and basis for treatment, protecting both the endodontist and the patient.

Making Your Case Presentation The seven essential elements of case presentation are summarized by the mnemonic DORBAT-C, which stands for diagnosis, options, risks, benefits, alternatives, treat ments, and costs. Most practice management software programs supply visual aids (Fig 40- 3), videos, PowerPoint presentations, or website links that can add multiple dimensions to a case presentation. Verbal presentations should be simple and short but repeated in three different ways and supplemented as necessary with visuals. This method makes allowances for your patients' differing personality types, learning approaches, and communicating styles. It is beneficial for the endodontist to explain his or her rationale for diagnosis and treatment options to the patient and then ask the patient to verbalize the rationale for his or her decision. Dual feedback improves understanding and communication by providing a window into the thought process of each participant.

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Keys to Effective Communication

ANTHONY L. HORALEK, DDS , MS , PA

NORTH RALEIGH

ENDODONTICS’"

NORTH RALEIGH ENDODONTICS 8330 BANDFORD WAY RALEIGH , NC 27615 ( 919) 256-3996 WWW . NORTHRALEIGHENDO .COM

.

May 15* 2014 Dr. I.B. Outstanding 1234 South Main Street Raleigh, NC 27614

Dear Dr. Outstanding:

Endodontic treatment on Mrs. Happy Patient was completed today, Wednesday, March 27 , 2013 for tooth #3.

Final Treatment:

Prognosis:

Core Buildup Material Used: Restorative Recommendations

#3 non-surgical root canal treatment was completed today in two treatment sessions, Four canals ( to include the MB2) were located, treated, and obturated with gutta percha and Roth's sealer. The tooth was restored with a dual -cure composite resin. #3 had an unusual anatomy with fused palatal and disto-facial roots. The crack terminated 1 mm coronal to the cemento-enamel junction. The long-term prognosis is questionable, due to the presence of a crack. Happy was advised of this during consultation and would like to retain #3 for as long as possible. Dual-cure composite resin Cuspal-coverage restoration, as soon as possible

Pre-op #3

Post-op #3

As always, I.B., we look forward to providing your patients with outstanding endodontic treatment. Your support and confidence is greatly appreciated. Thank you for allowing us to be part of your dental team and for referring Mrs. Happy Patient.

Sincerely, Anthony L. Horalek , DDS, MS Diplomate, American Board of Endodontics Fig 40- 4 Postoperative report. (Courtesy of Dr Anthony L. Horalek, Raleigh, North Carolina.)

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Communication Posttreatment Fig 40- 5 Face-to - face postoperative chairside discussion reinforces a positive doctor-patient relationship.

Financial Discussions

Communication Posttreatment

Financial concerns are a critically important part of the communication process. Fee presentations and financial arrangements should be made prior to the initiation of treatment. The doctor or a staff member can perform this task, preferably in a quiet, private setting using as few words as possible. In addition, patients must be provided with a written breakdown of charges and any special financial arrangements that are made. Once the pa tient agrees to the charges and financial arrangements, this aspect of treatment should be de- emphasized. All future conversations should be centered on the patient's therapy and well-being.

The moment of truth begins when treatment has been concluded. At this point, most patients would like to know your assessment of the procedure and what they should expect in terms of postoperative discomfort. This is a crucial time for both patient and doctor. Resist the opportunity to rush out of your operatory and leave the discussion with your patient to your dental assistant. A short slide presentation on the computer screen showing radiographs and photographs of the patient's tooth taken through the microscope is an excellent visual aid. Active listening and a reassuring demeanor will go a long way toward demonstrating to your patients that you care and that you are an involved professional (Fig 40- 5 ).

Communication During Treatment

Review any postoperative instructions at least three times before the patient leaves your office, once each by the doctor, assistant, and receptionist. Certain patients may relate better to staff than to the doctor, and repe tition assures maximal comprehension of these instructions. It also helps to provide written instructions, par ticularly for geriatric and anxious patients, in addition to access via a website. Accompanying your patients to the front desk, shaking their hands, and wishing them well are

The time spent actively treating your patient is one of the most important aspects of communication. Because patients are at their most vulnerable when the procedure is initiated, doctors should reassure and connect with them periodically through a multiplicity of approaches. The simple "tell, show, do " approach and the use of verbal time cues and procedural updates during treatment all serve to reinforce connection with the pa tient. Tactile communication by both doctor and assistant using a soft, reassuring touch may also be a comfort to some patients, provided there are no cultural restric tions prohibiting it.

.

excellent final touches When the patient is escorted to the front desk, the conversation with the receptionist should never start with, "That will be X dollars." The receptionist should ask the following patient -centered questions before collecting money or scheduling additional visits:

•How was your visit?

•How are you feeling?

•Do you have any questions about the postoperative instructions? •Do you have any other questions?

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Keys to Effective Communication

Conclusion

When the treatment is complete, it is recommended to send a final report not only to the referring dentist(s) but to the patient as well. This additional contact point will reinforce your professionalism and thoroughness.

Whether through nanowires, signaling molecules, barks, winks, or tweets, living beings exchange information through some form of communication. Innovations such as the Internet, smartphones, social networks, and text messaging have changed how we communicate. The endodontic office is a unique environment where a multitude of communication skills are necessary to properly assess and provide treatment in a professional and predictable manner. Although societal trends may point us away from face-to-face interactions, endodontic clinicians who favor these communication modalities and develop additional communication skills will continue to be identified in their respective communities as truly ex ceptional practitioners.

Postoperative Call Either the endodontist or a staff member can make the postoperative telephone call to the patient after a treatment visit. This can take place on the evening of the appointment or during the next business day. It is recommended that if you see patients on Friday, your postoperative calls should be made Friday afternoon or evening. Waiting to call your patients 3 days later may be considered poor form by both your patients and their referring doctors. Always structure the call in a positive format and be sure that whoever makes the call smiles while speaking. Enthusiasm and empathy go a long way.

Reference I. AIswany AA. " Egypt in the Dentists Chair." nytimes.com. December 30, 2013. http://v/ww.nytimes.com/2013/12/31/ opinion/alswany-egypt-in-the-dentists-chair.html. Accessed 2 July 2014.

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CHAPTER

Andrew L. Shur, DMD

Quality Intraoral

Radiography

Radiographs are an essential part of endodontic therapy. Clear, diagnostic radiographs set the stage for all subsequent treatment and provide guidance during treatment and medicolegal documentation. Preoperative radiographs provide information for diagnosis, depict tooth anatomy, and provide valuable clues about challenges associated with treatment and prognosis. Postoperative radiographs reflect the quality of treatment performed and serve as a baseline record for monitoring the health status of the tooth. If quality endodontic treatment is our goal, we must set the bar high for the quality of our radiographs. Poor-quality radiographs reflect poorly on the clinician performing the care. They make diagnosis more difficult and hinder every step of the treatment process. They also convey a negative message to other dental professionals involved in the patient 's care. This chapter is intended for doctors and ancillary personnel who are experienced at taking radiographs, rather than beginners. Its purpose is to improve the quality of radiographs irrespective of whether one uses film, phosphor plates, or digital sensors.

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Quality Intraoral Radiography for Endodontics

Fig 41- 1 (a to c ) Examples of well- taken prooperative radiographs.

entation (Fig 41-3). This is particularly true when the pa tient has long roots or when a size 1 sensor is being used. In most cases, it allows the root ends to be captured on the image with a paralleling technique (Fig 41-4), rather than having to foreshorten the teeth to capture the apices. Images can be captured this way most of the time in the mandible, because the floor of the mouth can be displaced, allowing ideal sensor placement. Gently slip the sensor under the patient's tongue and away from the mandible, and have the patient hold it securely with his or her teeth (Fig 41-5). In most cases, this can be done with minimal pa tient discomfort. The maxilla can be more problematic due to anatomical structures and constraints. A shallow palate, long roots, narrow arch, or a maxillary torus can prevent ideal sensor placement. In some cases, the sensor can be positioned toward or at the midline to take advantage of the palatal vault, thereby obtaining proper sensor orientation (Fig 41 -6). A cotton roll between the sensor holder and the opposing teeth can help stabilize the sensor. Occasionally, if the patient has long roots and a high palatal vault, the sensor can be placed in a vertical orientation in the maxilla (Fig 41 -7). Once the sensor is properly placed, stability is import ant. Any movement by the sensor will result in blurring of the image ( see Fig 41-2h). A sensor-positioning device stabilized with the patient's teeth provides the best stability (see Fig 41- 5). This method works well even with files or gutta -percha cones in the patient 's tooth (Fig 41-8). Sometimes a cotton roll placed to the posterior helps with stability as well. Some clinicians have patients stabilize the positioning device with their hand. This is generally poor practice and may contribute to blurred images and poor positioning.

The Perfect Radiograph A radiograph should show the entire tooth from above the level of the crown to several millimeters beyond the apices. It should include the entire periapical radiolucency. The tooth should be centered on the image, and the top edge of the image should be parallel to the occlusal plane. The images should be undistorted, with the proper horizontal and vertical angles, and neither elongated nor foreshortened. The radiograph needs to be taken at the proper peak kilovoltage (kVp), milliamperage (mA), and time so that the density of the image is neither too dark nor too light. The image should not be pixilated or blurry and should not be "cone cut." The image should be free of scratches or lines, which show up as artifacts. Examples of satisfactory radiographs are shown in Fig 41-1. Some of the common errors are shown in Fig 41-2. The figure legends describe how to identify, troubleshoot, and correct these common errors. Sensor (film) placement is the key to quality radiographs. A poorly placed sensor results in less than ideal images even if everything else is done correctly. The sensor should be placed close to the teeth being imaged, if possible, with the upper edge parallel to the occlusal plane and the body of the sensor as parallel as possible to the long axis of the tooth. This allows the x -ray beam to come in perpendicular to the sensor and tooth, thus providing the least distorted images. When the ideal sensor position cannot be obtained, a bisecting angle technique can be used. The images are somewhat distorted compared with the paralleling technique, but adequate images can still be obtained. The best images are often obtained when the long axis of the sensor is used in a vertical rather than horizontal ori-

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The Perfect Radiograph

Fig 41- 2 Examples of common errors with radiographs, (a ) Radiograph with a “cone cut . ” In addition, the occlusal surfaces of the teeth are not parallel to the edge of the image, and the horizontal angle of the x - ray head was positioned too far toward the mesial, shifting the buccal roots to the distal and causing overlap and distortion on the image. Proper positioning of the sensor and rotating the x - ray head with a greater distal angle would correct these problems (b ) The apices are cut off , but the image is otherwise satisfactory. The best method to correct this problem is by rotating the sensor 90 degrees and retaking the radiograph with the same vertical and horizontal angulations. The x - ray head could be repositioned to a more negative vertical angle, but this would result in a foreshortened image, (c) In most cases, the apices of the teeth should be in the apical third of the image. This can be corrected by rotating the x-ray head to a more positive (or less negative) vertical angle, (d) The radiograph is “running downhill.” This can be corrected with proper positioning of the sensor. ,

Fig 41- 2 (cont ) (e) The radiograph is “running uphill.” (f ) Underexposed radiograph. The darkness or lightness of a radiograph is from the combination of the mA, kVP, ex posure time, and distance between the x - ray head and the sensor. Light radiographs can usually be corrected by adding more exposure time or moving the x -ray head closer to the patient, (g ) Overexposed radiograph. This can usually be corrected with a shorter exposure time or by increasing the distance between the x - ray head and the sensor, (h ) An image that is blurry due to movement during the imaging process. Having the patient stabilize the radiograph holding device with their teeth helps avoid this problem, ( i ) Elongated radiograph. This is corrected by repositioning the x-ray head at a greater positive vertical angle, ( j ) Foreshortened radiograph. This is corrected by repositioning the x - ray head at a greater negative vertical angle.

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Fig 41- 3 A sensor placed in a holding device in a vertical orientation. This orientation usually allows the x -ray head to be placed at an ideal vertical angle to capture the entire tooth while minimizing distortion.

Fig 41 - 4 (a ) Radiograph taken in the vertical orientation, (b) Radiograph not taken in the vertical orientation. Note how (a ) has less distortion than (b) and provides more information, including the entire radiolucent area in the bone.

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Quality Intraoral Radiography for Endodontics

Fig 41 - 5 With rare exceptions, a vertically ori- Fig 41- 6 In order to position the body of the sensor parallel to the long axis of the teeth in the ented sensor can be placed comfortably in the maxilla, is it sometimes necessary to position it at the patient ’s midline, (a ) The sensor against the mandible. lingual surface of the molars. Note the high angle that is required to capture the apices of the teeth. (b ) A more ideal positioning with the sensor at the midline.

Fig 41- 8 Have the patient stabilize the holding device with his or her teeth whenever possible. This can be done with most devices even when there are files or gutta-percha cones in the canals. Fig 41- 7 (a and b ) Patients with a high palatal vault sometimes allow vertical orientation of the sensor in the maxilla.

Fig 41 - 9 (a and b) One advantage of digital sensors is the ability to make corrections without moving the sensor. Note the clearer view of the apices in b after reangulation of the x -ray head.

Fig 41-10 Positioning the x-ray head at a severe horizontal angle will sometimes provide additional useful information. In some cases, an exaggerated distal angle is the only way to clearly view the distobuccal root of the maxillary molars.

head shifted the structures in Fig 41-9 to show a clearer, less distorted view. In some cases, the only way to get a clear image of one or multiple root ends is with a severely horizontally angled radiograph, as seen in Fig 41-10. A severe horizontal angle from the distal aspect is sometimes the only way to obtain a clear view of the distobuccal root of maxillary molars.

Making Corrections One of the benefits of digital sensors is the easy correction of angulations. When an initial radiograph is improperly angulated, the x-ray head can be quickly adjusted and a second image taken. Note how reangulation of the x-ray

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The Value of Bitewings

Fig 41-11 (a and b ) Example of a radiograph that was “ sharpened” on the computer. Note the sharper image in (b).

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Fig 41 -12 fa and b ) Sometimes adjustment of the contrast makes the radiograph more useful.

Fig 41-13 fa and b) Example of an inverted image. The inverted image is most useful in showing obturated teeth.

Fig 41 -14 fa and b) Preoperative bitewings can be very useful in endodontics, especially in cases where diagnosis is difficult. In this case, a large area of cervical decay in the maxillary right first molar was hidden by the crown in the periapical radiograph.

Fig 41-15 fa and b) Preoperative bitewings can also be very helpful in determining restorability and can provide a truer view of the relationships of the alveolar bone to the cen/ical area of the tooth

.

Digital Enhancement

The Value of Bitewings

Most digital systems allow the radiographs to be enhanced or the viewing characteristics to be changed. Examples include sharpening the image (Fig 41-11), adjusting the contrast (Fig 41-12), black/white inversion (Fig 41-13), coloring, cropping, and magnification. These may help the clinician in diagnosis, aid in patient education, and/or provide a better presentation in a case report.

Bitewing radiographs are usually discussed in the realm of restorative dentistry and periodontics. However, they can be very useful in endodontics as well and should be taken preoperatively in addition to periapical radiographs. Bitewings can show decay or poor restorative margins that may otherwise not be seen in periapical views (Fig 41-14). This may be helpful when diagnosis is not clear-cut. Bitewings are often more helpful than periapical radiographs in determining the amount of remaining coronal tooth structure, especially in the important cervical areas, and in determining the level of decay in relation to the crestal bone (Fig 41-15). They are also helpful in determining periodontal status, including the level of the osseous crest and the extent of bone loss. 341

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Quality Intraoral Radiography for Endodontics

Fig 41-16 A soft padding material can be Fig 41-17 If the sensor is placed correctly, many of the holding devices allow fairly accurate replaced on a sensor for patient comfort . production of radiographs at different appointments. In this case, a Rinn instrument was used for preoperative ( a ) and postoperative (b) radiographs.

Clinical Tips

Summary

•If a patient has a shallow floor of the mouth and feels

The ability to take a perfect radiograph should be viewed as essential when performing high- level, highquality endodontics. A well-taken radiograph is one of the many key factors that sets the stage for all subsequent treatment. Obviously, a well-taken radiograph has no bearing on the long-term outcome of any given endodontic case; however, if we as clinicians are striving to set our treatment bar high, it begins and ends with a high-quality radiograph.

the sensor cutting into the tissue, try padding the sensor with a sticky pad to make the insertion more comfortable (Fig 41-16). For • patients with a midline maxillary torus, the best image can sometimes be obtained by placing the sensor on the far side of the palate, behind the torus. •Patients who gag can be problematic for radiography. Placing salt on the patient's tongue sometimes helps to control the gag reflex. Also, having the patient lift a leg sometimes serves as a distraction long enough to capture a radiograph. For some patients, the gag reflex is less of a problem once the area is anesthetized. •Multiple angled radiographs sometimes provide useful information. •With consistent sensor placement, holding devices such as the Rinn instrument (Dentsply) allow reproducible angles for preoperative (Fig 41-17a), postoperative (Fig 41-17 b), and recall radiographs. This makes comparisons more valid.

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Index Page numbers followed by "f " indicate figures; those followed by "t" indicate tables; those followed by "b" indicate boxes

A Access cavity esthetic restoration of, 234-237, 235 f-237 f in metal-ceramic crown, 235, 236f Access cavity preparations armamentarium for, 92f, 92-93 burs for, 92, 92f caries/restorative/anatomy-leveraged, 96f challenges to, 100b, 100-102

cone beam computed tomography applications to, 91, 91 f crowns for, 228

definition of, 89 dentin preservation during, 89-91, 101, 102f endodontic in anterior teeth, 93 f-94f, 93-95, 95b in canines, 93-95, 94f in incisors, 93 f-95 f, 93-95 in molars, 97-98, 98 f in posterior teeth, 95-100, 97b in premolars, 96 f, 97-98 ferrule effect, 91, 91f fiber post and composite resin, 229, 230f instrument binding prevention through, 102, 103 f objectives of, 90b orifice-directed approaches, 98f, 99, 101, 110, 111f pulp chamber morphology, 90, 90f refining tools used in, 92, 92f restorative /caries-leveraged, 100, 10Of root canals description of, 90, 90f orifices, 98 f, 99, 101, 110, 111f projections, 98f, 99 " stepped," 96 f, 98 f technology used in, 91 through restoration removal, 94f, 95 in tipped mandibular molar, 101f unconventional, 94f, 95 ACCU- BEAM video adapter, 34f

Adapters photo, 22-23, 23f video camera, 32-33, 33f-34f Air abrasion, 242 All-ceramic crown, 240f, 242f Alumina glass, 239t Aluminosilicate glasses, 238 Amalgam buildups, silver, 232, 232f Analog video, 30t Anesthetic delivery, 49, 49 f Angled radiographs, 121, 131f Ankylosis, 268-269, 269 f Anterior teeth. See also specific teeth. access cavity preparations in, 93 f-94f, 93-95, 95b mandibular, 116f-117 f, 117 maxillary, 116, 116f Aperture, 18t Apical barrier case studies of, 304-308, 305 f-308 f mineral trioxide aggregate as, 301, 302f

placement of immature teeth strengthening after, 302 technique for, 302-303, 303f Apical constriction, 105 Apical foramen, 105, 105 f, 115 Apical infection, 190f Apical periodontitis, 139f Armrests, for assistant's stool, 8, 8f Aspect ratio, 30t, 31 f Assistant endodontic training of advanced skill sets, 51 anesthetic delivery, 49, 49 f canal irrigation, 50 file bending, 49, 50f file transfer, 49, 49 f microscope positioning, 47, 47 f mirror swapping, 48, 48 f overview of, 46-47 reading hand signals, 48, 48 f rotary file transfer, 50, 50f Stropko Irrigator, 51, 51f microscope binoculars for, 323 monitor for, 15, 15 f platform for, 13-15, 14f scope for, 10, 12f, 12-13, 16t, 20, 20f stool used by, 8, 8f suctioning by, 8, 9f—10f transitioning of, to clinical practice, 51

B Back pain, 16t Back wall design, 13-15, 14f Beam splitter low-light, 36, 37 f for photography, 20f, 20-22, 22f for videography, 31-32, 32t, 37 , 37 f-38 f Binoculars, inclinable, 12, 12f Bioceramics, 301, 310-311. See also Ceramics; Mineral trioxide aggregate. Biodentine, 310, 313 Biologic width, 275 Bisphosphonates, 205 Bitewing radiographs. See also Radiographs, calcified canals, 121, 122 indications for, 341, 341f

Bonded amalgam in mandibular molar with severe breakdown, 221-222, 222f in maxillary molar with severe breakdown, 222-223, 223f self-curing adhesive system for, 233 Bonding to ceramics, 240-242, 2411 to lithium disilicate, 241 to zirconia, 241 " Braiding " technique, for bypassing instrument segment, 164-165, 165f

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Index etching of, 240 glassy phase of , 238 identification of, 240, 240f nanoceramics, 239 processing methods for, 239t types of, 239t Cervical dentin, 90, 91f Cervical resorption case study of, 79f

Brightness, of video display, 36 Burs, 92, 92f, 151 Bypassing of instrument segment, 164f, 164-165 of ledges, 160-161, 161 f of silver point, 177 f—178f, 177-178

c C + file, 185 CAD/CAM technology, 239, 239t Calcified canals/ teeth angled radiographs of, 121, 131f bitewing radiographs of, 121, 122 case studies of, 124f—129f, 124-129 clinical management of, 123-124 cone beam computed tomography of, 77, 121 description of, 120 dyes used to localize, 123, 123f locating of, 121b, 121-123, 122f-123f mandibular incisors, 123f mandibular molars first, 125, 126f-128f, 129 second, 127, 127f third, 129, 129f maxillary incisors, 124f, 124-125, 126f-127f, 127 maxillary molars, 127-128, 128f maxillary premolars, 125, 125f microscopic localization of, 122, 122f radiographs of, 121, 122 troughing of, 122, 122f Calcium hydroxide apexification with, 301 as dressing, 153, 262, 264f tissue-dissolving properties of, 166 Calcium sulfate, 308 Camcorder, 38, 38 f Camera. See DSLR camera; Video cameras. Canals. See Root canal(s). Cancellier Instrument Removal System, 162, 162f

cone beam computed tomography imaging of, 79 f invasive. See Invasive cervical resorption, photographs of, 42, 42f C-file, 185 Chair, patient, 6, 6f-7f Charge-coupled devices, 34 Circle of influence, 4, 5 f Clearfil Porcelain Bond Activator, 237 Clinical examination, 332 Communication in case presentation, 333, 334f in clinical examination, 332 in diagnostic outcomes, 332 effective, 331 financial discussions, 335 in first appointment, 332 first impressions affected by, 332 posttreatment, 335f, 335-336 during treatment, 335 Complex fractures, incisors with case studies of, 294f-297 f, 294-297 management of, 293-297 mineral trioxide aggregate for, 294, 297 vital pulp therapy for, 292 Composite resin fiber post and, 229, 230f in invasive cervical resorption surgical treatment, 223224, 224f opaque, 234, 235 f with post and core for premolar restoration, 224-225, 225 f pre-endodontic buildup with, 212 Composite video cables, 34, 35t

Canines access cavity preparations in, 93-95, 94f mandibular, 93-95, 94f Cannulas, for separated instruments, 162f-163f, 162-163 Carbide burs, 92 Caries invasive cervical resorption versus, 248 photographs of, 226f Caries risk, 203, 203 f Caries/restorative/ anatomy-leveraged access, 96f Carr suturing technique, 328-330, 329f Case presentation, 333, 334f Castroviejo Gomel type needle holder, 321, 321f, 328, 329f CBCT. See Cone beam computed tomography. CCD. See Charge-coupled devices. CDJ. See Cementodentinal junction. Ceiling mounts, for microscope, 10, 11 f Cementodentinal junction, 104-105 Ceramage Opaque Dentin composite, 237 Ceramic post, 174 Ceramic primers, 241-242 Ceramics bonding to, 240-242, 2411 classification of, 239t-240t description of, 238-239

Computed tomography cone beam. See Cone beam computed tomography, medical model of, 55-56 resorption imaged using, 252, 252f Cone beam computed tomography access cavity preparation applications of, 91, 91f advantages of, 56, 57 f-58f ALARA principle with, 56, 71 anatomic determinations using, 77, 77f, 81f-82f artifacts with, 71, 75, 75 f case study uses of, 78, 79f-85f description of, 55 diagnostic uses of calcified canals, 121 C-shaped canals, 149, 150f increases in, 69 non-endodontic, 69, 79f perforations, 72, 73f-74f periapical rarefactions, 74, 74f, 79f-80f resorption, 69, 69f-70f, 79f root canal curvatures, 130 root cracks, 75, 75 f-76f, 80f trauma, 74-75, 75 f

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Index "unknown " findings, 76, 76 f endodontic model of, 56-58, 57 f-58 f endodontic surgery planning uses of, 78, 83f financial considerations for, 68 guidelines for, 72 horizontal fractures on, 283, 284f intangibles regarding, 69 intra - treatment uses of, 78, 84f isotropic nature of images, 76 learning curve for using, 69 office-directed access uses of, 59f patient preparation for, 67-68 physical layout for computers, 61-62, 62f design considerations, 59-60, 60f—61 f imagers, 59-60, 60f—61f, 68 information technology, 61-62, 62f reading room, 60-61, 61f regulatory considerations, 59 private-practice, in-house model of, 56, 61 pseudo-pan view, 63f, 63-64 pseudo-periapical view, 63f, 63-64 radiation exposure reductions with, 56, 71 reports and reporting checklists for, 67 features included in, 66 final, 66-67 findings included in, 66 language used in, 65-66 sample, 66f software for, 66-67 retreatment applications of, 78, 81 f—82f root canal evaluations, 91 satisfaction of search errors, 62, 71

diagnosis of, 149 f-150f, 149-150 endodontic treatment of access methods, 151f—152f, 151-152 calcium hydroxide dressing, 153 instrumentation, 151 obturation, 153 preoperative periodontal considerations, 150-151 restoration, 153-154 retreatment after, 154, 154f-155f periapical radiographs of, 149 posts with, 153, 154f

D Debris, root canal, 165-166, 166f " Decision points" approach, to restorability evaluations, 209-210, 21Of Decompression case study of, 318, 319 f clinical technique for, 318 definition of, 316 materials used in, 317 of periapical cysts, 316-317 summary of, 319 Decoronation, flapless, 268-272, 269f—271f Definitive restoration, 42, 42f Dens invaginatus, 78 f Dental delivery systems, 13, 13f Dental operating microscope. See Microscope. Dental truss, 99, 99 f Dentin cervical, 90, 91f cleaning of, 233, 233f pericervical, 90, 91f, 101, 110f preservation of, during access cavity preparations, 89-91, 101, 102f radicular. See Radicular dentin, sclerotic, 120 Dentinal tubules, 122 Depth of field, 18t Diamond burs, 92, 92f Digital radiographs, 341, 341f Digital single-lens reflex camera. See DSLR camera. Digital video, 30t Digital visual interface cables, 34, 35t Direct ultrasonics, for removing separated instruments, 161, 161f Disease-specific outcomes, 110 Distobuccal root, of maxillary molars, 117, 135f Doctor monitor for, 15, 16f stool used by, 8, 8 f Doctor cart, 13, 13f DSLR camera AC adapter power supply for, 26 camera body, 24 description of, 21, 24 high definition video-enabled, 39, 39f settings for, 24, 25t DSLR photo adapter, 22-23, 23 f Dual-curing composites, 213 Dual-iris diaphragm, 20, 20f-21f, 26 Dyes, for calcified canal identification, 123, 123f

sensitivity of, 71

specificity of, 71 studies patient preparation for, 67-68 reviewing of, 62-64, 63f-64f tooth relationship to vital structures imaged using, 77-78, 78 f treatment planning uses of, 77-78 working length determinations using, 106 Cone freeze technique, 133-134, 134f Cones, gutta-percha, 136-140, 137f-139f Conservative endodontics. See also Access cavity preparations. challenges to, 100b, 100-102 rationale for, 90-91 Consult photographs, 42, 42f Co-observation scope, 10, 12f, 12-13, 16t Co-observation tube, 10, 47, 47 f Co-observation/assistant microscope, 20, 20f Core buildup composite, fiber post cementation and, 231, 231 f resin matrix for, 220-221, 221f CPR - 1 ultrasonic tip, 169 f Crop-frame cameras, 24 Crown lengthening, 275 Crown -to-root ratio, 282 Crypt development, 45 f C-shaped canals cone beam computed tomography of, 149, 150 f configuration of, 148, 149f description of, 77, 81 f, 148

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H

I Index elevation of, 45 f suturing of, 328 Flapless decoronation, for replacement resorption, 268272, 269f-271f Focal length definition of, 23 of the objective lens, 18t, 19f 4:3 aspect ratio, 30t Fractures. See Root fractures. Frame rate, 30t Frustum, 99, 99f Full-frame cameras, 24

E

EAL. See Electronic apex locator. Eggbeater grip, 325, 325 f EIR. See External inflammatory resorption. Electronic apex locator, 106f, 106-107 Endo Chuck, 185 Endo Extractor System, 162 EndoGuide burs, 92, 92 f, 168f, 185 EndoHandle, 100, 101f EndoSequence Root Repair Material, 301, 302f, 308 Endosonore, 185 Endo- Z bur, 92 Ergonomic operatory design assistant monitor for, 15, 15 f platform for, 13-15, 14f stool for, 8, 8f assistant/co-observation scope, 10, 12f, 12-13, 16t back wall design, 13-15, 14f circle of influence, 4, 5 f

G Gain, 311 Gates Glidden drills, 93 Global Surgical dual-iris diaphragm, 26 Gonon-type post removal system, 171, 171f Grab and pull technique, for silver points removal, 177, 177f Gripping, of microsurgery instruments, 324f-325 f, 324-325 Gutta -percha carriers, removal of, 180f—181f, 180-182 obturation with delivery unit for, 142 high-temperature, thermoplasticized injectable. See High-temperature, thermoplasticized injectable gutta -percha obturation, master cones, 136-140, 137 f—139f selection of, 142 solvents used to dissolve, 176

doctor monitor for, 15, 16f

stool for, 8, 8f doctor cart or delivery system, 13, 13f elements of, 4, 5t microscope mounting, 10, 11 f microscope parameters, 4, 6, 6f patient chair and headrest, 6, 6f-7f problems and solutions for, 16t Ergonomics classes of motion, 4, 5 t, 13f principles of, 4-16 ERRM. See EndoSequence Root Repair Material. Ethylenediaminetetraacetic acid, 176, 185 Excellence in Endodontics 2 mirrors, 26 Exposure time, 18t

H Hand files

description of, 132, 140 gutta -percha carrier removal using, 180 Russian Red removal using, 184-185, 185f

External inflammatory resorption case study of, 266f-267 f, 266-267 characteristics of, 246t, 250-251, 251f radiographic imaging of, 266f treatment of, 262, 264, 264f Extraradicular matrix, 302 Extrusion immediate surgical, 275-280, 276b, 277f-279f orthodontic. See Orthodontic extrusion. Eyepieces, 22

Hand signals, 48, 48f

Headrest, on patient chair, 6, 6f-7f Heated plugged technique, for gutta-percha carrier removal, 181, 181f Heated technique, for gutta -percha carrier removal, 180, 181f Hedstrom technique for gutta-percha carrier removal, 181, 181f for silver points removal, 178 High eyepoint, 22 High-definition, 30t High-definition multimedia interface cables, 34, 35t High-definition video-enabled DSLR camera, 39, 39f High-temperature, thermoplasticized injectable gutta-

F Feedback, 333 Feldspathic glass, 238, 239t Ferrule effect, 91, 91f Fiber posts, 227, 228f, 229, 230f Fiber-reinforced composite posts, 167, 168f, 172-173, 173f 50/ 50 beam splitter, 21, 22f, 32t, 37, 37 f Figure eight suture, 327 File bending of, 49, 50f rotary, transfer of, 50, 50f transfer of, 49, 49f ultrasonic, 166, 166f Financial discussions, 335 First appointment, 332 First impressions, 332 Flap

percha obturation

armamentarium and materials for, 142

benefits of, 141 canal preparation for, 142 case studies of, 144f—146f, 144-146 complications of, 146-147

extrusions, 147 in long, curved roots, 145, 145 f in long canals, 144, 145 f sealer, 142-143 short fill with, 146-147 technique for, 142-144, 143f—144f in thin canals, 144, 144f

0 SKSH

03»

由　扫描全能王　扫描创建

Index Horizontal fractures in anterior teeth, 283, 284f case study of, 290f—291f, 290-291 clinical technique for, 289f, 289-290 cone beam computed tomography of, 283, 284f location of, 283, 284f long-term prognosis for, 283, 284f mineral trioxide aggregate for, 288, 288f, 290-291 nondisplaced, 283 pulpal vitality in, 283 radiographs of, 284f trauma as cause of, 287 f treatment of, 288, 288f Hydrofluoric acid, 242f Hydrogen light, 24

of internal approach to, 253 nonsurgical, 253-257, 255 f-256f recommendations for, 253 surgery, 258-261, 259 f-260f treatment planning of, 250f IR. See Internal resorption. Iris, 18t dual-iris diaphragm, 20, 20f-21f, 26 video, 33 Irreversible pulpitis, 203 Irrigants, 176 IrriSafe file, 185 IRS system, 162, 162f ISO. See International Organization for Standardization. treatment

I

K

ICR. See Invasive cervical resorption. Imagers, for cone beam computed tomography, 59-60, 60f—61f, 68 Immature teeth strengthening of, after apical barrier placement, 302 vital pulp therapy in, 310-315 Immediate surgical extrusion, 275-280, 276b, 277f-279f Incision, 45 f Incisors access cavity preparations in, 93f-95 f, 93-95 with complex fractures case studies of, 294f-297f, 294-297 management of, 293-297 mineral trioxide aggregate for, 294, 297 vital pulp therapy for, 292 mandibular, 94f, 95, 123 f maxillary. See Maxillary incisors. Inclinable binoculars, 12, 12f Indirect ultrasonics, for removing separated instruments, 161 Instruments microsuturing. See Microsuturing, instruments for. segment of, bypassing of, 164f, 164-165 separated. See Separated instruments. Integrated video camera, 38 Interlaced scanning, 30t

K-files, 185 Knot tying, 326

L " Lasso technique " for separated instrument removal, 163, 163f for silver point removal, 178 LED light, 24 Ledges, bypassing , 160-161, 161f ' Leica M320, 33f Leucite glass, 239t Light sources, for microscope photography, 24 Lithium disilicate, 239t, 240, 241f Low-light beam splitter, 36, 37f Luting cements, 229

M Macro Ring Lite MR-14EX, 24 Macro Speedlight SB-21B, 24 Magnification definition of, 18t eyepiece power effects on, 22 microscope, 4 Mandibular anterior teeth, 116f—117 f, 117 Mandibular incisors, 123f Mandibular molars calcification of, 125, 126f-129f, 129 first, 43f, 125, 126f, 187f root canal preparation in, 117-118 root structure of, 98 second, 127, 127f third, 129, 129f

Internal resorption case study of, 265, 265f characteristics of, 246t, 246-247, 247f description of, 72, 72f nonperforating, 263, 263f perforating, 264, 264f radiographic imaging of, 265f treatment of, 262-264 International Organization for Standardization, 18t, 19f Interrupted sutures, 326, 326f Invasive cervical resorption

Mandibular premolars first, 58f root canal preparation in, 117, 117 f Mattress sutures, 326, 327 f Maxillary incisors calcification of, 124f, 124-125, 126f-127f, 127 fracture of, 277, 277f, 284, 284f, 296f-297 f horizontal fracture of, 287f immature, 294f immediate surgical extrusion of, 277, 277 f-279f reinjury of, 295 f Maxillary molars calcification of, 127-128, 128f

caries versus, 248 case studies of, 254-257, 255 f-256f, 259f-260f, 259-261 characteristics of, 246t composite resin restoration in surgical treatment of, 223-224, 224f diagnosis of, 247f-248f, 247-249

Heithersay classification of, 250f hemorrhagic appearance of, 249, 249f radiographic imaging of, 247 f-248f, 247-248, 255f-256f, 259f

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I—1

Index disadvantages of, 301

first, 77, 116f

in horizontal fracture treatment, 288, 288f, 290-291

palatal root of, 116-117

root canal preparation in, 116f-117 f, 116-117 second, 43 f, 189f Maxillary premolars calcification of, 125, 125 f root canal preparation in, 116 Maximum flute diameter, 115, 115t, 117 Mesiobuccal root, of maxillary molars, 117 Metal halide light, 24 Metal posts benefits of, 228 description of, 168 Gonon -type removal system for, 171, 171f instruments for, 168, 168f passive, 168-170, 169f-170f restorative material removal, 168 silver amalgam buildups and, 232, 232f threaded, 168, 169f tube and composite for, 172, 172f Metal-ceramic crown access cavity in, esthetic restoration of, 235, 236f radiograph of, 240f MFD. See Maximum flute diameter. Microscope calcified canals identified using, 122, 122f circle of light for, 6, 6f

pulpotomy with complex amalgam in immature molar, 225, 226f for complex fractures in incisors, 294 vital pulp therapy using, 292 Minimal apical foramen diameter, 105, 105f, 107 Mirrors

Excellence in Endodontics 2, 26 swapping of, 48, 48f Molars access cavity preparations in, 97-98, 98f mandibular. See Mandibular molars, maxillary. See Maxillary molars. Monitor for assistant, 15, 15f for doctor, 15, 16f video display, 36

Monofilament sutures, 323, 323f Motion, classes of, 4, 5t, 13f Motorcycle grip, 324, 325f, 329f Mounting, of microscope, 10, 11f MTA. See Mineral trioxide aggregate. Multiplanar curvatures, of root canal, 132f, 132-133 Munce Discovery Burs, 92, 92f, 168f, 173 Mutually protected occlusion, 202

ergonomics of. See Ergonomics, magnification of, 4 mounting of, 10, 11f photography use of. See Photography, microscope positioning of, by assistant, 47, 47f role of, in endodontic practice, 3 six-step, 4, 6f suturing using. See Microsuturing. videography use of. See Videography, microscope.

N Nanoceramics, 239 Neck pain, 16t Needle holder, 321, 321f, 328, 329f Needles, suturing, 322, 322f Nickel-titanium hand files, 140 Nickel-titanium rotary instruments, 131 Nonperforating internal resorption, 263, 263f Nonsurgical endodontics invasive cervical resorption treated with, 253-257, 255 f-256f photographic set for, 42f-45f, 42-45

,

Microsuturing advantages of, 321 instruments for assistant microscope binoculars, 323 gripping of, 324f-325f, 324-325 microsurgeon 's stool, 323, 324f needle holder, 321, 321 f, 328, 329f suture scissors, 322, 322f suturing needles, 322, 322f tissue forceps, 322, 322f knot tying, 326 overview of, 320 surgeon posture and position of, 325 stool for, 323, 324f

o Obstructions instrument segment, 164f, 164-165 ledges, 160-161, 161f nonspecific, 165-166, 166f root canal debris, 165-166, 166f separated instruments. See Separated instruments. Obturation of C-shaped canals, 153 goals of, 136 gutta -percha master cones for, 136-140, 137f-139f with high-temperature, thermoplasticized injectable

sutures

description of, 322-323, 323f figure eight, 327 interrupted, 326, 326f mattress, 326, 327 f vertical mattress, 326, 327 f

gutta -percha

armamentarium and materials for, 142 benefits of, 141 canal preparation for, 142 case studies of, 144f-146f, 144-146 complications of, 146-147 extrusions, 147 in long, curved roots, 145, 145f in long canals, 144, 145 f sealer, 142-143 short fill with, 146-147

suturing Carr technique of, 328-330, 329f clinical techniques for, 328-330 general rules for, 325

Mineral trioxide aggregate apical barrier use of, 301, 302f for complex fractures in incisors, 294, 297 description of, 192-194, 193f

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Index technique for, 142-144, 143f-144f in thin canals, 144, 144f photographs after, 42, 42f with Russian Red. See Russian Red. of severely curved root canals, 133-134, 134f tooth restoration after, 227

procedural sequencing, 192 restoration placed over repair material, 193, 193 f technique for, 192-194 strip, 72, 74f

Periapical cysts, 316-317 Periapical radiolucency, 215, 216b Periapical rarefactions, 74, 74f, 79f-80f

Occlusion, 202 1CCD camera, 34 OpalDam, 218-219, 219f Operatory design, ergonomic assistant monitor for, 15, 15f platform for, 13-15, 14f stool for, 8, 8f assistant/co-observation scope, 10, 12f, 12-13, 16t back wall design, 13-15, 14f circle of influence, 4, 5f

Pericervical dentin, 90, 91f, 101, 110f, 116 Periodontal ligament, 104, 268 Periodontal probing, 45f Periodontal status, 203 Photo adapters, 22-23, 23f

Photographs

applications for, 41, 42f in final report, 44f, 45 need for, 41, 42f standard set of for nonsurgical endodontics, 42f-45f, 42-45 for surgical endodontics, 45, 45f timing of, 42 Photography, microscope accessories needed for beam splitter, 20f, 20-22, 22f co-observation/assistant microscope, 20, 20f DSLR photo adapter, 22-23, 23f dual-iris diaphragm, 20, 20f —21f, 26 light source, 24 overview of, 19, 19b reticle, 23 ring flash, 24, 27 10 x eyepieces, 22 basics of, 17, 18t, 19f image transfer from camera to computer, 26 insufficient light for, 27 parfocal adjustment for, 25, 25b scenarios for, 26-27 setting up for, 24-26, 25b sufficient light for, 26-27 Pier abutments, 205, 205 f Pillow, on chair headrest, 6, 6f Pits and grooves, 237, 237f Pixel resolution, 30t Plastic gutta -percha carriers, 181f, 181-182 Portiligature suturing, 326

doctor monitor for, 15, 16f stool for, 8, 8 f doctor cart or delivery system, 13, 13 f

elements of, 4, 5t microscope mounting, 10, 11f microscope parameters, 4, 6, 6f patient chair and headrest, 6, 6f-7 f problems and solutions for, 16t OPMI PROErgo microscope, 39f Organic solvents, 176 Orthodontic extrusion case study of, 284f, 284-285 clinical considerations for, 282-283 clinical technique for, 283 considerations for, 284 contraindications for, 282 description of, 281 indications for, 282, 282f invasive cervical resorption treated with, 250 patient factors that affect, 283 root form, 282-283, 283 f root length, 282 smile line, 283

P Paper point method, for working length determination, 106, 107f Parallel-optics microscopes, 10 Parfocal adjustment, 25, 25b Partial pulpotomy, 311, 312f Passive metal post, 168-170, 169f-170f Patient chair, 6, 6f-7 f Patient-centered outcomes, 110 Peeso drill, 220f Pen grip, 324, 324f Perforations, root cone beam computed tomography imaging of, 72, 73f-74f definition of, 191 furcal, 194, 195f iatrogenic, 191-196, 192f—196f lateral, 194-196, 195 f periodontal tissue response after, 191 post, 196, 196f repair of case studies of, 194-196, 195f—196f materials used in, 192

Post(s) cementation of, 231, 231f ceramic, 174 composite resin with, for premolar restoration, 224-225 225 f in C-shaped canals, 153, 154f fiber, 227, 228f, 229, 230f fiber-reinforced composite, 167, 168f, 172-173, 173f identification of, 167, 168f

metal benefits of, 228 description of, 168 Gonon-type removal system for, 171, 171f instruments for, 168, 168f passive, 168-170, 169f-170f restorative material removal, 168 silver amalgam and, 231, 231f threaded, 168, 169f tube and composite for, 172, 172f nonmetal, 172-173, 173f-174f perforation, repair of, 196, 196f placement of, 303-304

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t J Index paralleling technique for, 338, 339f preoperative, 337 sensor placement for, 338, 339f-340f, 342f technique for, 338, 338f-340f tips for, 342 underexposed, 339f in vertical orientation, 338, 339f working length determinations using, 105-106, 106f Radix entomolarisis, 97 RadLex, 65 Reading room, for cone beam computed tomography images, 60-61, 61f Reconstruction artifacts, 75 Repetitive motion injuries, 8 Replacement resorption causes of, 268 characteristics of, 246t, 251-252, 252f flapless decoronation for teeth with, 268-272, 269f-271f

titanium, 167, 168 f, 169 zirconia, 174, 174f Posterior teeth, 95-100, 97b. See afso specific teeth. Postoperative call, 336 Postoperative report, 334f Posttreatment communication, 335 f, 335-336 Powder condensation, 239t Pre -endodontic buildup with composite resin, 212 method 1, 213b, 213-215 method 2, 215b, 215-216 " open sandwich " layered technique for, 215 overview of, 212 Preliminary read, of cone beam computed tomography image, 60

Premolars access cavity preparations in, 96f, 97-98 composite resin with post and core for restoration of, 224-225, 225 f mandibular first, 58f root canal preparation in, 117, 117f maxillary calcification of, 125, 125f root canal preparation in, 116 Pressed ceramic, 239t Primers, ceramic, 241-242 Process-related outcomes, 110 Progressive scanning, 30t Prolene, 323 f Pulp canal obliteration, 120 Pulp chamber, 90, 90f, 99

Resin matrix armamentarium for building, 219, 219f case studies of, 221-225, 222f-226f

bonded amalgam in mandibular molar with severe breakdown, 221222, 222f in maxillary molar with severe breakdown, 222-223, 223f

'

composite resin with post and core for premolar restoration, 224-225, 225 f mineral trioxide aggregate pulpotomy with complex amalgam in immature molar, 225, 226f for core buildup, 220-221, 221f stainless steel, 218 Resin-modified glass-ionomer cement, 215-216 Resolution of photographs, 18t, 19f of video, 30t Resorption case study of, 79f computed tomography of, 252, 252f cone beam computed tomography imaging of, 69, 69f-70f, 79f external inflammatory. See External inflammatory resorption. internal. See Internal resorption. invasive cervical. See Invasive cervical resorption. pathologic, 245, 246t photographs of, 42, 42f replacement. See Replacement resorption. types of, 245 Response time, of video display, 36 Restorability evaluations case studies of, 207 f—21Of, 207-210 "decision points" approach, 209-210, 21Of decision-making tool used in, 202f factors to consider in adjacent tooth support, 205, 205f age of patient, 206 caries risk, 203, 203f coronal tooth structure, 202f, 202-203 desires of patient, 206 fractured teeth, 206, 206f health status of patient, 205, 205f occlusion, 202 periodontal status, 203 previous endodontic treatment, 206 restorative treatment, 203

Pulp stones, 120 Pulp therapy, vital. See Vital pulp therapy. Pulpal floor anatomy of, 97 calcifications of, 121f magnification of, 122f Pulpal status photographs, 42, 42f Pulpitis, irreversible, 203 Pulpotomy full, 311 mineral trioxide aggregate with complex amalgam in immature molar, 225, 226f for complex fractures in incisors, 294 partial, 311, 312f

R Radicular dentin management of, 111-115, 119 in pericervical area, 111-112 "triangles " of, 111, 111f

Radiographs angled, 121, 131f, 340 bitewing, 121, 122, 341, 341f calcified canals/teeth, 121, 122, 131f " cone cut," 339f corrections with, 340, 340f digital enhancement of, 341, 341f digital sensors with, 340, 340f errors with, 339f horizontal fractures, 284f internal resorption, 265f invasive cervical resorption, 247f-248f, 247-248, 255 f-256f, 259f

p5o] 由　扫描全能王　扫描创建

Index risks associated with retaining of tooth, 203 tooth extraction, restorative options after, 205 tooth's role, 205 treatment plan, 206 risk factor reduction, 207

in maxillary premolars, 116 morphology preservation, 112, 113f overview of, 109-110 taper, 113, 113 f, 115 traditional strategies for, 112-114 projections, 98f, 99 sealer tract, 85 f taper of, 113, 113f, 115 in tooth with anomalous root form, 84f uninstrumented/missed, 42, 42f

Restorative procedures access cavity, 234-237, 235 f-237 f after obturation, 227 posts used in fiber, 227, 228 f, 229, 230f metal, 228, 231, 231f overview of, 227 selection of, 228, 228f silver amalgam buildups and, 232, 232f types of, 228 in restorability evaluations, 203

Root canal curvatures case study of, 134-135, 135 f cone beam computed tomography of, 130 description of, 114 high-temperature, thermoplasticized injectable guttapercha obturation in, 145, 145f management of, 130-135, 131f—135f multiplanar, 132f, 132-133 obturation of, 133-134, 134f severe, 130-135, 131f-135 f Root cracks cone beam computed tomography imaging of, 75, 75f-76f, 80f findings associated with, 75 photographs of, 42, 42f vertical, 204f Root fractures complex. See Complex fractures, incisors with. cone beam computed tomography imaging of, 74-75, 75 f horizontal in anterior teeth, 283, 284f case study of, 290f-291f, 290-291 clinical technique for, 289f, 289-290 cone beam computed tomography of, 283, 284f location of, 283, 284f long-term prognosis for, 283, 284f mineral trioxide aggregate for, 288, 288f, 290-291 nondisplaced, 283 pulpal vitality in, 283 radiographs of, 284f trauma as cause of, 287 f treatment of, 288, 288f photographs of, 42, 42f restorability evaluations and, 206 vertical, 151 Root perforations. See Perforations, root. Root resection, 45 f Root resorption case study of, 79f cone beam computed tomography imaging of, 69, 69f-70f, 79f photographs of, 42, 42f Rotary file transfer, 50, 50f Rotary method, for gutta-percha carrier removal, 181 Round needles, 322, 322f Russian Red asymptomatic tooth with, 184 clinical categorization of teeth with, 184 historical overview of, 183 illustration of, 184f

Reticle for photography, 23 for videography, 34 Retreatment bypassing ledges, 160-161, 161 f chamber cleanup in, 176 in C-shaped canal, 154, 154f—155 f irrigants used in, 176 obstruction removal. See Obstructions, post removal. See Post(s). solvents used in, 176 Retrofilling, 45 f Ring calcification, 122, 127, 128f Ring flash, 24, 27 Root

apex of, 105, 105 f apical anatomy of, 105, 105 f, 114-115, 146 curvatures of, 77, 77 f forms, 77, 77 f, 81f Root canal(s) access cavity preparation considerations, 90, 90f " blocked out " of, 165 calcified. See Calcified canals. cone beam computed tomography of, 91 convergence profiles of, 112f C-shaped. See C-shaped canals. curvature of. See Root canal curvatures. debris obstruction in, bypassing of, 165-166, 166f depth of, 84f irrigation of, 50 in maxillary molars, 97-98 mesial, 99 mesiobuccal, 77, 81f—82f midroot split of, 77, 82f, 85 f morphologic variations of, 90, 97, 112, 113f orifices, 98f, 99, 101 in premolars, 97 preparation of apical anatomy, 114-115 case studies of, 118f-119 f, 118-119 curvature considerations, 114 file profile, 115 flute diameter, 115, 115t longevity model, 110 in mandibular anterior teeth, 116f-117 f, 117 in mandibular molars, 117-118 in mandibular premolars, 117, 117f in maxillary anterior teeth, 116 in maxillary molars, 116f-117 f, 116-117

retreatment

of

in apical third, 186 armamentarium for, 184-185 case studies of, 186-190, 187f-190f in coronal third, 185-186

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F

L

—

I J

Index instruments used in, 184-185, 185 f in middle third, 186 technique for, 185-186 solvents used with, 185

T

Taper, of root canals, 113, 113f, 115 Teeth. See also Anterior teeth; Posterior teeth; specific teeth. calcified. See Calcified canals/ teeth, isolation of, 212 restorability evaluations for. See Restorability evaluations. structural compromise of, 212. See also Tooth structure. Threaded metal post, 168, 169f 3CCD camera, 34, 35f Tissue forceps, 322, 322f Titanium posts, 167, 168f, 169 Titanium splint, 291f Tofflemire retainer, 218, 219f Tooth Atlas, 112 Tooth platform, 99 Tooth restorability index, 202, 202f Tooth structure coronal, 202f, 202-203 post selection based on, 228 Training, of assistant advanced skill sets, 51 anesthetic delivery, 49, 49f canal irrigation, 50 file bending, 49, 50f file transfer, 49, 49f microscope positioning, 47, 47f

s

Satisfaction of search errors, 62 Sclerotic dentin, 120 Scope, assistant/ co-observation, 10, 12f, 12-13, 16t Separated instruments bypassing of, 164f, 164-165 description of, 160-161 removal of, 160-163, 161 f—163f tube/cannula techniques for, 162f—163f, 162-163 ultrasonics for, 161, 161 f Shannon-Nyquist theorem, 121 Shutter speed, 18t Silane, 241 Silver amalgam buildups, metal posts and, 232, 232f Silver points fragment of, in canal, 179, 179f " handle," 177, 177f properties of, 177 removal of bypass technique used in, 177f-178f, 177-178 extraction devices for, 178 grab and pull technique, 177, 177 f Hedstrom technique for, 178 indirect ultrasonic activation for, 178-179 " lasso " technique for, 178 surgery for, 179 two-file technique for, 178, 179f Sinus tract, 305 f-307f, 319f Six-step microscope, 4, 6f 16:9 aspect ratio, 30t, 31f Slip casting, 239t Smile line, 283 Sodium hypochlorite, 176 Solvents gutta -percha removal using, 176 Russian Red removal using, 185 Squirt technique, 134, 146 Static contrast ratio, of video display, 36 Stool for assistant, 8, 8f for doctor, 8, 8f for microsurgeon, 323, 324f Strip perforations, 72, 74f Stropko Irrigator, 51, 51f, 169, 169f

mirror swapping, 48, 48f overview of, 46-47

reading hand signals, 48, 48f rotary file transfer, 50, 50f Stropko Irrigator, 51, 51f Trauma cone beam computed tomography imaging of, 74-75,

75 f horizontal fractures caused by, 287 f occlusal, 202 Trendelenburg position, 6 TRI. See Tooth restorability index. Trichloroacetic acid, 253, 259, 260f TRIO 610, 33f, 35f Troughing, 122, 122f, 127 "Tube and Hedstrom " technique, 163, 163f Tubes, for separated instruments, 162f-163f, 162-163 12.5 X eyepieces, 22 2CCD camera, 34 Two-file technique, for silver points removal, 178, 179f Two-port 50/ 50 beam splitter, 32, 32t Tying knots, 326

Suctioning by assistant, 8, 9f—10f suction placement for, 10, 10f Surgical endodontics, 45, 45f Surgical extrusion, immediate, 275-280, 276b, 277 f-279f Suture(s) description of, 322-323, 323f figure eight, 327 interrupted, 326, 326f mattress, 326, 327 f photograph of, 45f removal of, 45 f vertical mattress, 326, 327 f Suture scissors, 322, 322f Suturing needles, 322, 322f

u Ultra high-definition, 30t Ultrasonic file, 166, 166f Ultrasonics for bypassing canals blocked with debris, 165-166 for cement removal, 168 for removing separated instruments, 161, 161f for Russian Red retreatment, 184 for silver point removal, 178-179 Uninstrumented/missed root canal, 42, 42f

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Index

V

Vital pulp therapy case studies of, 311-314, 312f 314f clinical technique for, 311 in immature teeth, 310-315 indications for, 292 pulpotomy, 311 requirements for, 310

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Verbal presentation, of case, 333 Vertical mattress Gottlow suture, 326, 327f Vertical root fractures, 151 Video cables, 34, 35 f, 35 t Video camera adapter, 32-33, 33f-34f Video cameras description of, 34 integrated, 38 Video chain, 31, 36 Video display, 36 Video iris, 33 Video recording devices, 36

w Warm vertical compaction, of gutta -percha, 137 Warm vertical technique, for severely curved root canals, 133-134, 134f White balance, 18t Wide field eyepieces, 22

Videography, microscope accessories needed for beam splitter, 31-32, 32t, 37, 37 f-38f overview of, 31, 31b recording device, 36 reticle, 34 video cables, 34, 35 f, 35t video camera, 34, 37-38 video camera adapter, 32-33, 33f-34f video display, 36 video iris, 33 advantages of, 29 basics of, 29, 30t

Working length apical anatomy of tooth root, 105, 105f cone beam computed tomography of, 106 definition of, 104 determination of, 105-107, 107b electronic apex locator for, 106f, 106-107 importance of, 104 paper point method for determining, 106, 107f radiography of, 105-106, 106f

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X

configurations for camcorder, 38, 38f 50/50 beam splitter and external microscope video camera, 36, 36f high definition video-enabled DSLR cameras, 39, 39f integrated video camera, 38 low-light beam splitter and external microscope video camera, 36, 37 f

Xenon light, 24

Z Zeiss 20 beam splitter, 21, 37 Zeiss pico, 33f Zirconia, 239t Zirconia crowns bonding to, 241 identification of, 240, 240f Zirconia posts, 174, 174f

Vignetting, 23 Virtual Beamsplitter, 21, 22f, 32t Viscostat, 219, 220f

[353]

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Contents Part I . The Dental Operating Microscope 1. Operatory Design and Ergonomics for Microscopic Endodontics 2. Setting Up Your Dental Operating Microscope for Photography 3. Setting Up Your Dental Operating Microscope for Videography 4. Photodocumentation for Endodontics 5. Training an Assistant to Work Under an Operating Microscope Part II . Cone Beam Computed Tomography ana Endodontics 6. Incorporating CBCT Imaging into Endodontics 7. Clinical Applications of CBCT Imaging in Endodontics

Part III. Nonsurgical Endodontic Procedures 8. Access Cavity Preparations 9. Working Length 10. Preparation of the Root Canal System 11. Clinical Management of Calcified Teeth 12. Clinical Management of Severely Curved Canals 13. Obturating with Gutta-Percha Master Cones

14. Obturation with High-Temperature, Thermoplasticized, Injectable Gutta-Percha 15. Clinical Management of C-Shaped Canal Configurations

Part IV. Retreatment 16. Bypassing Ledges, Separated Instruments, and Other Obstructions 17. Removing Metal and Fiber Posts 18. Removing Silver Points and Gutta-Percha

Part V. Restorative Considerations 21. Evaluating Restorability Prior to Treatment 22. The Pre-endodontic Buildup 23. The Customized Resin Matrix 24. Restorative Procedures with Posts 25. Esthetic Restoration of Access Cavities 26. Bonding to Ceramic Materials Part VI . Resorption 27. Diagnosis and Treatment Planning for Resorption 28. Nonsurgical Treatment of Invasive Cervical

Resorption 29. Surgical Treatment of Invasive Cervical Resorption 30. Treatment of Internal Resorption and External Inflammatory Resorption 31. Flapless Decoronation for Teeth with Replacement Resorption Part VII . Trauma Management 32. Immediate Surgical Extrusion 33. Orthodontic Extrusion 34. Clinical Management of Horizontal Fractures 35. Clinical Management of Incisors with Complex Fractures

Part VIII . Other Topics 36. Clinical Management of Teeth with Open Apices with the Apical Barrier Technique 37. Vital Pulp Therapy in Immature Teeth 38. Decompression 39. Suturing Under the Microscope 40. Keys to Effective Communication 41. Quality Intraoral Radiography for

Endodontics

Carriers 19. Retreatment of Teeth Containing " Russian Red" Endodontic Paste 20. Repair of Iatrogenic Perforations

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SBN - 978- 0-867 5-677-5

90000

9 780867 156775

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