Ceramic veneers: contact lenses and fragments [1 ed.] 9788560023

Citation preview

PAULACARDOSO & RAFAELDECURCIO

Florianópolis/SC - Brazil 2018 - 1st edition

TITLE Ceramic VENEERS: contact lenses and fragments 1st Edition, 2018 Editora Ponto Ltda. ISBN: 978-85-60023-19-6 AUTHORS Paula de Carvalho Cardoso & Rafael Decurcio GRAPHIC DESIGNER Emmanuel Fontes PORTUGUESE REVIEWER Giovanni Secco ENGLISH VERSION Fabio Luiz Andretti, DDS, MSD, PhD Paul Anthony Luz, PENR This book is a publication of Ponto Publishing Ltd., Avenida Othon Gama D’Eça, 900, Sala 810, Centro, Florianópolis, Santa Catarina, Brazil, CEP 88015-240. No part of this publication may be reproduced without prior permission from the Editor. INFORMATION: [email protected] www.editoraponto.com.br facebook.com/EditoraPonto @EditoraPonto (55 48) 3223 9150 Cardoso, Paula Ceramic venners : contact lenses and fragments / Paula Cardoso & Rafael Decurcio ; [English version Fabio Andretti, Paul Anthony Luz]. -- 1. ed. -- Florianópolis, SC : Editora Ponto, 2018. Título original: Facetas : lentes de contato e fragmentos cerâmicos. ISBN 978-85-60023-19-6 1. Odontologia 2. Cerâmicas dentárias 3. Facetas dentárias 4. Lentes de contato I. Decurcio, Rafael. II. Título. 18-16899 Cibele Maria Dias - Bibliotecária - CRB-8/9427

CDD-617.692

authors

PAULA DE CARVALHO CARDOSO MS, PhD in Restorative Dentistry / UFSC Specialist in Restorative Dentistry / HRAC-USP Professor, Specialization Course in Restorative Dentistry/ ABOGO Coordinator of the Course “Ceramic Veneers – Building a Predictable Protocol”/ ABO-GO

RAFAEL DE ALMEIDA DECURCIO MS Oral Rehabilitation / UFU Specialist in Periodontics / ABO-GO Professor, Specialization Course in Restorative Dentistry/ ABO-GO Professor of the Course “Ceramic Veneers – Building a Predictable Protocol”/ ABO-GO

LÚCIO JOSÉ ELIAS MONTEIRO MS, Restorative Dentistry / SLM-Campinas-SP Professor, Specialization Course in Restorative Dentistry/ ABO-GO Professor of the Course “Ceramic Veneers Building a Predictable Protocol”/ ABO-GO

MARCUS VINÍCIUS N. M. DOS R. PERILLO DE FREITAS Specialist in Restorative Dentistry / ABO-GO Professor, Specialization Course in Restorative Dentistry/ ABO-GO Professor of the Course “Ceramic Veneers Building a Predictable Protocol”/ ABO-GO

TERENCE ROMANO TEIXEIRA Specialist in Restorative Dentistry/ ABO-GO Specialist in Periodontics / Uberlândia Specialist in Implant Dentistry / Uberlândia Professor, Specialization Course in Restorative Dentistry/ ABO-GO Professor of the Course “Ceramic Veneers Building a Predictable Protocol”/ ABO-GO

WILMAR PORFÍRIO DE OLIVEIRA CDT, Owner Wilmar Porfírio Dental Laboratory Professor, Specialization Course in Restorative Dentistry/ ABO-GO Professor of the Course “Ceramic Veneers Building a Predictable Protocol”/ ABO-GO

ANA PAULA RODRIGUES DE MAGALHÃES MS, Dental Clinics / School of Dentistry / UFG Specialist in Restorative Dentistry / ABO-GO Associate Professor of the Department of Restorative Dentistry / UNIP-GO Professor, Specialization Course in Restorative Dentistry/ ABO-GO Professor of the Course “Ceramic Veneers – Building a Predictable Protocol”/ ABO-GO

coauthors

PEDRO LUÍS ALVES DE LIMA Specialist in Restorative Dentistry / ABO-GO Assistant Professor, Specialization Course in Restorative Dentistry/ ABO-GO Assistant Professor of the Course “Ceramic Veneers – Building a Predictable Protocol”/ ABO-GO

AMIN DE MACEDO MAMEDE SULAIMEN Professor, Specialization Course in Restorative Dentistry/ ABO-GO Assistant Professor of the Group ImplantePerio / ABO-GO Specialist in Periodontology and Implant Dentistry / ABO -GO MSD Implant Dentistry / SLMandic

JOÃO CHRISTOVÃO PALMIERI FILHO Master in Prosthodontics / UnB Specialist Implant Dentistry / ABO-DF Specialist in Occlusal Diagnostics and Rehabilitation / DATO Dental Practice Buenos Aires

GUIDO CIRILO FERREIRA Specialist in Restorative Dentistry / ABO-GO Assistant Professor, Specialization Course in Restorative Dentistry/ ABO-GO Assistant Professor of the Course “Ceramic Veneers – Building a Predictable Protocol”/ ABO-GO

ALTAMIRO FLÁVIO RIBEIRO PACHECO Specialist Prosthodontics / UFU Professor, Specialization Course in Restorative Dentistry/ ABO-GO Accredited member of the Brazilian Society of Aesthetic Dentistry (SBOE)

ANDREA MELO PhD Student Restorative Dentistry / UERJ MSD Materials Science / IME Specialist Prosthodontics / UVA Graduate in Periodontics / OCEX

JÚNIO S. ALMEIDA E SILVA MS, PhD in Restorative Dentistry / UFSC Specialist in Restorative Dentistry / UFSC Visiting Researcher, Department of Prosthodontics / Ludwig-Maximilians Universität, Munchen, Germany

FERNANDA G. V. PALHARES SAKEMI Specialist in Restorative Dentistry Professor, Specialization Course Restorative Dentistry / ABO-Uberlândia-MG

JULIANA NUNES ROLLA Specialist in Restorative Dentistry / UFSC MS, Restorative Dentistry / PUC-RS Associate Professor, Restorative Dentistry / UFRGS Professor Specialization Course, Restorative Dentistry / UFRGS

JULIANA ROMANELLI Specialist in Orthodontics and Dentofacial Orthopedics / UNICASTELO MSD Oral and Maxillofacial Prosthodontics/ FO-USP Assistant Professor, Courses of Excellence in Periodontology and Implant Dentistry / ImplantePerio Institute

CRISTIANO SOARES CDT / Integração-Campinas-SP Shareholder and Owner of the Laboratory “J. Soares”, Head of the sector of customized dental works / Campinas-SP Ceramist, Private Practice, Prof. Dr. Eric Van Dooren / Antwerp-Belgium Coauthor of the book “The Pursuit of Aesthetic Excellence”, Editora Napoleão Coauthor, QDT Year Book 2014 and 2015, Quintessence

coauthors

LUCIANO REIS GONÇALVES Specialist in Periodontics / USP-Bauru Specialist in Implant Dentistry / UNESP-Araçatuba Specialist in Prosthodontics/ Funorte-Goiânia

VICTOR CLAVIJO PhD, Restorative Dentistry / UNESP-Araraquara MSD, Restorative Dentistry / UNESP-Araraquara Specialist Restorative Dentistry / UNESP-Araraquara Specialist in Implant Dentistry / SENAC-SP

RENATA GONDO MACHADO PhD, Restorative Dentistry / UFSC Specialist, MSD, Restorative Dentistry / UFSC Associate Professor Restorative Dentistry / UFSC

MAX SCHMELING PhD, Restorative Dentistry / UFSC MSD, Restorative Dentistry / UFSC Peer-reviewer, Restorative Dentistry, Journal of Dentistry and Odontology - Japan

JUSSARA BERNARDON MS, PhD in Restorative Dentistry / UFSC Specialist in Restorative Dentistry / UFSC Professor Graduate Program - MSD and PhD / UFS

LEANDRO DE CARVALHO CARDOSO PHD, OBMFS / UNESP-Araçatuba Master in OBMFS/ UNESP-Araçatuba Specialist in CTBMF / CFO Specialist in Implant Dentistry / APCD-Araçatuba

preface

Brazil is not “great” because of its immense territory, but because of its people (although many would have us believe the opposite). Rafael, Paula and the entire staff of this wonderful book inwhich I have the honor to introduce, are an undeniable proof of what I believe in and for many years what I have been saying. People are the greatest wealth of any country, and this is no different in Brazil. I met Paula, more than 10 years ago, during a dental event, while she was still an undergraduate student in the city of Anápolis, Goiás, Brazil. Afterwhich I had the privilege of being her professor during her masters and doctorate courses at the Federal University of Santa Catarina in Florianopolis, where I teach. In contrast, I met and became Rafael’s friend not long ago. Yet, deep down, I have the impression that I have always known him, such is our affinity and mutual respect. I have had the pleasure and the joy of working with them both in the specialization courses in Dentistry and in some of our short-duration courses on ceramic veneers at ABO Goiás. They are one more proof that dreaming is an universal right and that our dreams do not get fulfilled on their own. They only manifest true through hard, persistent and patient work. The work is what carries out the dreams. To accomplish another one of his dreams, that is, this wonderful book, Paula, Rafael and the entire group who work with them are being reaffirmed more and more, a great example to thousands of young people who want to build, as they have, a beautiful career. This book, in addition to its up-to-date content, is easy to understand and scientifically supported, and overwhelmingly illustrated with immaculate photographs. Countless case reports optimally documented reveal the extensive experience of the authors and co-authors in this particular field of Dentistry. Indeed, a wonderful book. If you have any questions, I suggest that you carefully go over each page and then proceed reading without any hurry. I am sure you will agree with me and will also be proud of what they were able to produce, at such a young age. Congratulations, my friends. I am so proud of you all.

Luiz Narciso Baratieri

acknowledgements

Despite being the first to be read in books, acknowledgements are usually the last to be written. Authors focus their energies on objective, scientific and technical issues, and at times fail to conclude their work with the proper acknowledgments. With the hope of not committing the offense of forgetting anyone, and as well not categorize people in order of importance or interest, we would like to express our sincere gratitude to everyone who participated in this literary project, from its very conception through to its editing. We would also like to acknowledge the attributes, and not solely the characters. First (even being impossible to attribute Him adjectives) we thank GOD! CONFIDENCE. To all of the patients presented here and to everyone else that had offered us their confidence and their hope for change. Since the introduction of the clinical course entitled “Ceramic Veneers - Building a Predictable Protocol”, a paramount importance has been given to the patient who can successfully make our innovative and unique dream come true. ALTRUISM. A term more than synonymous of those individuals like Tereza, Cleide, Wauner, Denise, Henrique, Thiago, Maria, Jacyra, Ângela and many others. Thanks to ALL of the employees who selflessly supported the work undertaken by the Restorative Dentistry Team from ABO-GO over the years LOYALTY. Cleide Rocha and Katarina de Souza exemplify the embodiment of this concept. There is no day, time, difficulty, workload or mood ... their loyalty transcends rational issues. With them “a mission given is a mission accomplished”. WILLINGNESS. Without hesitation, we received a “yes” from all of our co-authors which costed them several hours a year from their families, friends and leisure time, in order for them to engage in the full cooperation of the completion of this project. MAGIC. Fontes materialized into pages what we only could have ideally dreamed of. COMPLICITY. Summing up heterogeneous characteristics, our team unites itself in complicity with the total absence of personal vanity and an unmatched desire to see that each and every task is “well done”. Lúcio Monteiro, Altamiro Flávio, Marcus Vinícius Perillo, Terence Romano, Maria Geovânia, Ana Paula Magalhães, Guido Ferreira, Pedro Lima, Amin Mamede and Alfeu Neto form the group of authors and testimonies of this book. FRIENDSHIP. With a relationship initiated for the pursuit of knowledge, our students and alumni have become great friends, each of which has contributed to the growth of the teaching-learning experience and have actively participated in the construction of the clinical cases as well as in the life-time transformation of innumerous patients. EXCELLENCE. Since Dentistry is predominantly technical, where obedience to a protocol and the repetition of steps are what lead to the anticipated results, José Carlos Romanini, Murilo Calgaro, Leonardo Bocabella and Cristiano Soares are outlying individuals which have gifted this book with amazing cases, incorporating inspiration and naturalness to such a technical field of Dentistry. PARTNERSHIP. Of those few that life seldomly offers. DUDU MEDEIROS became a partner and friend, left responsible for much of what has been carried out by our team in recent years. In this book, far more than photographing most of our patients, he gave us his expertise and an eye for beauty that escapes ones common sense.

Paula Cardoso & Rafael Decurcio

special acknowledgements

We dedicate a special chapter to Wilmar Porfirio. Much more than a service provider, leading a team of over 40 employees, Wilmar Porfírio, turned into a great partner and friend, who became largely responsible for carrying out this book. Simple, humble and “hill-billy” born, as he likes to call himself, Wilmar is a genius in service to the field of Cosmetic Dentistry. By quirk of fate or unexplainable convenience, he (we fear that ever) will still be recognized by technically idealizing the ceramic injection technique for fabrication dental contact lenses. But it does not matter! Devoid of personal vanity and excessive ambition, the genius is content to be satisfied with the results of the work of his team jointly, the smiles captured by comparative “before and after” pictures and kind emails of thanks. Yes... he is like that! He is an unconditional supporter of our ideas and projects, and as a professor of our courses, he works with the simplicity of his personality and with a non-academic lecturing skill based on the brilliance of what he does and who he is! Wilmar Porfírio, we extend our most sincere gratitude to you for carrying out most of the cases presented here, for teaching openly your technique, and for the opportunity of living with your elevated spirituality through your simple way of seeing and living life!

Paula Cardoso & Rafael Decurcio

dedication

“I dedicate this book to my parents Paulo and Lucienne, who taught me to dream and gave me all the support for my personal and professional growth; to my brothers Paulene and Leandro, who always walk next to me; to my grandmothers, for sharing their experience; my sons Leonardo and Bruno, who make me strong and stimulate my betterment each and every day; and to my love, Rafael Decurcio, for holding my hand in such a sublime way without giving up and with the certainty that happiness is reachable!” PAULA DE CARVALHO CARDOSO

“I dedicate this book to my little princesses, Rafaela and Giovana, that one day will understand the real importance of work and dedication as a means to happiness; to my brothers, Paulo and Daniel, who never refused their implicit or explicit support; to my mate and accomplice, Paula Cardoso, who taught me what only hearts know; and, in a special way, to my parents, Paulo and Wilma, for their example of uprightness of character, for the unconditional demand placed upon my studies and further for their own dedication to work and for the greatest love I’ve ever felt in the world.” RAFAEL DECURCIO

eternally grateful

By far, this is the most difficult text to be written throughout the course of the production of this book. All of the months of hard work and dedication, the numerous literature searches, the hundreds and hundreds of hours of photographic documentation of the whole process of work are not as difficult as to express in written words your importance in our lives. Professor, Master Supervisor, Coordinator, Head, Owner, Reference, Friend, Companion, or anything else that fits, Baratieri is our everything! Directly and absolutely responsible for everything that we have achieved professionally and personally, since his presence in our lives. With a strong focus and a sharp sincerity, he is able to command with the strength of a father and the love of a mother. Incomprehensible decisions in the present are reflected into lucid solutions of tomorrow with that rare insight of the few. With frightening childlike energy, he urges all those that surround him always forcing us to walk with no thought of regret. We are sure that if we could bottle this elixir, we would be millionaires. But we do not! Neither us, nor anyone acting in Aesthetic Dentistry. We are already billionaires for the unique opportunity to be around him and take advantage of all the treasure he produced, produces and will produce for the common good. Baratieri.... to you forever grateful, we offer our canine faithfulness and our Spartan loyalty! WS Team forever!

Paula Cardoso & Rafael Decurcio

summary

SECTION I. INITIAL CHAPTER 1. A NEW AGE IN DENTISTRY CHAPTER 2. AESTHETIC PRINCIPLES CHAPTER 3. SHADE SELECTION AND REPRODUCTION IN CERAMIC VENEERS CHAPTER 4. AESTHETIC REHABILITATION PLANNING SECTION II. BEFORE CHAPTER 5. OPTIMIZATION OF THE AESTHETIC AND FUNCTIONAL RESULTS CHAPTER 5.1. THE RELEVANCE OF ORTHODONTICS AS AN INITIAL THERAPY BEFORE RESTORING WITH CERAMIC VENEERS CHAPTER 5.2. PERIODONTAL PLASTIC SURGERY CHAPTER 5.3. DENTAL BLEACHING CHAPTER 5.4. OCCLUSAL PLASTIC RESTORATIVE THERAPY SECTION III. IMPLEMENTATION CHAPTER 6. ON SIZE OF THE RESTORATIONS CHAPTER 6.1. PREPS FOR CERAMIC VENEERS CHAPTER 6.2. CERAMIC FRAGMENTS CHAPTER 7. CERAMIC SYSTEMS CHAPTER 8. IMPRESSION TAKING FOR CERAMIC VENEERS THE ESSENCE OF COMMUNICATION CHAPTER 9. TEMPORARY RESTORATIONS FOR CERAMIC VENEERS

26 30 70 90

124 126 146 178 194

226 228 268 296 316 338

SECTION IV. CEMENTATION CHAPTER 10. DENTAL ADHESION CHAPTER 11. RESIN CEMENTS CHAPTER 12. LUTING PROCEDURES

356 372 388

SECTION V. FOLLOW-UP CHAPTER 13. MAINTENANCE CHAPTER 14. FAILURES OF CERAMIC VENEERS CHAPTER 15. BEFORE AND AFTER

418 432 468

SECTION I. INITIAL

A NEW AGE IN DENTISTRY

CHAPTER 1

a new age in dentistry Paula de Carvalho Cardoso | Rafael Decurcio

Ceramics, resin cements, rehabilitation treatment planning, tooth morphology, aesthetic parameters, adhesion - whatever it may be the subject of contemporary dentistry to be presented, they are always to be preceded by a deep-rooted concept in humanity: Beauty! Both the operatory techniques and the physical and optical behavior of the materials have been widely studied in Dentistry throughout its history. However, how does one conceptualize Beauty objectively? How do we come to understand such an extensively conceptualized concept, which was revised throughout the entire history of mankind, which is neither tangible, nor generates unanimity, as well as people? The diversity of the beauty concept in constant change comes from the Pre-socratic era of philosophy, which lends strong mathematical association of beauty to shapes and accurate measurements. The European Renaissance, between the fourteenth and seventeenth centuries, rediscovered the concept of classical beauty, one in contrast to the Gothic Era, which conceptualized that non divine beauty was sinful and should be viscerally rejected. Later, Humanism revisited the concept of Beauty which once again came down to mathematical harmony and rational analytical order. Already in the Post-Modernist phase, beauty was once again philosophically rejected, appearing as an unsightly portrait in its artistic forms of expression. And today? How should we conceptualize Beauty? And what is the real significance of such great historical concepts and philosophical diversity in relation to such a thrilling and alluring theme? Perhaps no importance at all or it may be that they are fully important, depending upon ones point of view. If we imagine that we should guide our choices and decisions on current concepts, the historical philosophical changes are harmless. However, if we think that the concept of beauty is changing and that our choices today can reflect an unbearably ugly and unpleasant tomorrow, the History of Philosophy will at least help us by providing us with parsimony and wisdom to decide and act. In the beginning of this century, especially over the last eight years, Dentistry was greatly influenced by an incessant social quest for aesthetic perfection, creating a new and dangerous era: “The Age of Veneered Patients”. People have been treated in a standardized and digitized manner, by producing identical results for different people. Age, gender and physical characteristics have been excluded from the evaluation process in the pursuit for ease of treatment delivery to achieve this so called dreamed Aesthetic Perfection. But will the dreamed Aesthetic Perfection override the individuali?

28

Even facing all of the conceptual and philosophical changes to Beauty, we must react and reflect on the etymological concept of the word. In Greek, Beauty, or Beautiful, is defined as “time” and it is associated with a particular time. It can guide not only dental practice but also our vision of the world: it make us to come to understand the beauty of the buildings at the very time they were errected, the beauty of a small country village quitely opposed to our urban life, to the timeless beauty of the classical arts, the beauty of a smile in its respective age that possesses it, as well as the beauty of the white and the yellow. Etymologically, Beautiful is related to a time, it is all about the moment, the age, and gender. Beauty then, is individuality at that very moment in time. The aim of this book was to introduce a philosophical work based on established clinical protocols supported by literature on ceramic veneers, specifically on how to customize the treatment planning and to further implement aesthetically, functional rehabilitations without extending beyond its precise indication, blending patient’s expectation and professional’s decency and ethics.

29

chapter 2

aesthetic principles Paula de Carvalho Cardoso | Rafael Decurcio | Altamiro Flávio Pacheco Ana Paula Rodrigues de Magalhães | Marcus Vinícius Perillo

Promoting health and respecting the biology of the individual, have always been principles of treatments proposed in Dentistry, with the aim of conveying physical care and achieving highly physiological results. Following evolution and technological advances, Dentistry has come to address psychological aspects through aesthetic rehabilitations, ie, the ability to restore the physiological shape of a smile, respecting the patients’ biology, highlighting their positive aesthetic features, while adapting to their lifestyle, job and social status.13 Noting both of these aspects, it is imperative to settle which aesthetic standards one should be based, first of all upon factors related to health of the individual. Thus, the correct rehabilitation planning becomes essential. Given the importance of a smile and the complexity of its evaluation, a number of parameters such as facial, dentolabial, gingival as well as dental references are extremely important in identifying and recording all data needed to optimize the aesthetic appearance of the prosthetic rehabilitation.21,54 Thus, while focusing on the harmony between the face and hard and soft tissue components of the oral cavity,21 a method to display each case becomes mandatory. The patient-tailored analysis based on optimal aesthetic references, that seeks to achieve objective parameters for the implementation of aesthetic treatments, provides an opportunity for universalization of expertise to the most difficult task of Aesthetic Dentistry, treatment

FACIAL REFERENCE LINES Fradeani22 described the topics of facial analysis that should be addressed for each individual patient in cases of oral rehabilitation. According to the author, horizontal reference lines, vertical reference lines and facial proportions must be taken into consideration as a starting point in the aesthetic planning. Extraoral photos are used at the moment of the facial analysis and proper patient positioning is essential for carrying out the digital planning (see Chapter 4).22 Within these parameters, the main horizontal and vertical lines are: (Figure 1b) 1. the interpupillary horizontal line (passes through both pupils); 2. the horizontal line of the labial commissure (passes through the labial commissures); 3. the horizontal eyebrow line (passes through both eyebrows); 4. the vertical midline (center of the upper lip); 5. vertical lines of the nostrils (line tangent to the nasal alae); and 6. the horizontal line of the incisal edge. Horizontal reference lines are used to analyze the parallelism between the structures. The literature is unanimous on the importance of parallelism between horizontal lines of the face, such as the interpupillary, the eyebrow and the labial commissure lines.14,62 Often these references are used to guide the incisal plane, the occlusal plane and the gingival contour.22 32

FACIAL ANALYSIS

planning.

There is a statistically significant correlation between the interpupillary line and the incisal edge of the maxillary central incisors, regardless of gender.1 A study by Malafaia et al.45 reports that 70.59% of the studied population showed parallelism between the described lines. In situations where the interpupillary line and the commissure line are parallel, but diverge from the horizontal plane, they could still be used as a prosthetic rehabilitation guide.22 The facial midline is determined by the following points of reference: glabela, the tip of the nose and the tip of the chin. (Figure 2). The middle line is perpendicular to the interpupillary line and forms a “T”.48 This intersection of the midline

Figure 1b.

Figure 2a.

Figure 1a.

Figure 2b.

Figure 1. Frontal photo of the smiling patient (a) and the same photograph with the tracings of the horizontal and vertical lines (b). Figure 2. Frontal photo of the smiling patient with the marking of points (a) to guide the demarcation of the facial midline (b): glabela, tip of the nose and chin. Photographs by Dudu Medeiros.

33

with the aforementioned horizontal planes creates a type of organized structure in which it is possible to identify the presence or the absence of symmetry between the right and left sides of the face. The facial asymmetry tolerated between the right side and the left side is 3%; more than that the asymmetry is evident and aesthetically unpleasant.22 According to Kokich,36 from the prosthetic standpoint, the lack of alignment between the glabella, the nose tip, and the tip of the chin hinders the identification of the facial midline. In these situations, the center of the upper lip, or the lip filtrum should be used as the reference.28 (Figure 3) The optimal average dental lines (upper and lower) should be coincident each other and along the facial midline. However, Miller, Bodden and Jamison47 found that 70.4% of the studied sample showed coincidence of the dental midline with the facial midline. A

Figure 3a.

Figure 3d.

Figure 3b.

Figure 3c.

Figure 3e.

Figure 3. Patient Frontal photo (a-b) where there is no alignment of forming points of the midline, complicating its tracing (c). It was then traced following the philtrum (d). This patient also features titling of the bipupilar line. Photos after the rehabilitation of the patient, with the philtrum as reference of the midline, showing dentolabial and dentofacial harmony (e) although keeping discreet bilateral discrepancy of the upper lip volume while smiling.

34

slight misalignment between the upper and lower midlines is rarely perceived, especially by lay evaluators, who do not visualize up to 3 mm deviation;17,58,62 therefore, it does not represent an obstacle in obtaining optimal aesthetics. Nevertheless, some patients request a perfect coincidence between the interincisal midlines. Under these requests, clinicians and technicians attempt to realign the maxillary and the mandibular arches using the inclination of the dental axes which may cause an unpleasant aesthetic appearance.37 Clinically, in cases where there is pronounced deviation between the maxillary and the mandibular midlines which is not to be corrected prior through orthodontics, a manner to to achieve smoother and more pleasing results, even with the given limitations, by carrying out the rehabilitation with the proximal surfaces of the involved teeth as parallel as possible. (Figure 4)

Figure 4a.

Figure 4b.

Figure 4c.

Figure 4d.

Figure 4e.

Figure 3. Frontal photograph of the patient that presents deviation from the dental midline as to midline of the face (a) and close-up shot of the smile (b). Photography conventional preparations for ceramic veneer veneers carried out with greater reduction on the mesial surfaces of the teeth on the right side (c). In the final shots of the rehabilitation, the proximal surfaces were made parallel to each other(d), providing a satisfactory result, in that the deviation has not been fully corrected, but was softened by configuring the tooth shape (e).

35

The nostril lines are two imaginary vertical lines that are bilaterally tangent to the nose wing, which determines the interalar distance with the patient smiling. These lines can help in two aspects: (1) to analyze the symmetry of the nose with the face; and (2) help at assessing the optimal size of the six anterior superior teeth. (Figure 5) The nasal alae line determines the harmony of the nose with the face, something fundamental when planning, after all one can not have doubts about the patient’s complaint, as the disharmony often lies in the width of the nose, and not the dental condition.51 Thus, the nasal alae line determines if the nose is symmetrical, wide or narrow for the face.39,40 According to Gomes et al.,25 the ideal average interalar width during a smile is 38.7 mm for females and 43.1 mm for males. Another detail that brings harmony to the face is the nasal alae is that the line vertical tangent to the medial border of the sclera (“white of the eye”); conversely, the greater the distance of the nasal alae from the sclera, the most asymmetrical (wider or shorter) the harmony. Another important condition is that line of the nose wing should be tangent to the distal portion of the maxillary canines, which shows an optimal ratio for the width of the six anterior superior teeth during the smile,60 confirming the relationship between the structures described in the work of Gomes et al.25 This reference line, while providing data for the analysis of the nose symmetry in relation to the face and establishing the width of the six anterior teeth, helps in determining the distal or mesial positioning of the maxillary canines whether by tooth movement, either by the gaining of the labial volume of the anterior teeth in cases of lingual positioning of the crown. The line of the incisal edge, where the smile line or the incisal curvature is determined by an imaginary line that touches the incisal edges of the anterior superior teeth. This greatly influences the smile aesthetics. Ideally, the incisal edge is convex and should be parallel to the upper edge of the lower lip, which promotes radial symmetry or the incisal curve. This is present in 84.8% of cases.23,68,31 (Figure 6) However, the curvature of the lower lip is not always homogeneous and can present variations between both sides of the face including hyperactivity during smiling and with aging. Thus, it should be based on the horizontal reference because it is a fixed parameter and a static reference for leveling the incisal edges of the anterior superior teeth.62 (Figure 7) The lack of parallelism between the incisal plane and the curvature of the lower lip typically is due to a flatening of the incisal line or even inversion of the incisal edges, creating a negative anterior space and a significant smile artificial.2 Horizontal asymmetry occurs due to either functional or parafunctional wear or skeletal changes or both, and causes four aesthetic impairments : (1) the incisal edge of Figure 5.

Figure 5. Frontal photograph of the smiling patient with the tracing of nose wing lines allowing for the evaluation of the nasal symmetry with face, touching the medial border of the sclera; and the relationship to the dimension of the six anterior superior teeth touching the distal portion of the upper canines. Photograph by Dudu Medeiros.

36

Figure 6a.

Figure 6b.

Figure 6c.

Figure 6d.

Figure 7a.

Figure 7d.

Figure 7b.

Figure 7c.

Figure 7e.

Figure 6. Frontal smile photography of a patient with tracing representing its incisal edge (red) and the outline of the lower lip (yellow) (a). The incisal edge is concave and does not match the lip contour. With the lips retracted and the teeth on a dark background, this concave shape is even more evident (b). After the aesthetic rehabilitation of the patient, was obtained the radial symmetry with the coincidence of these two lines in smile and harmony of the incisal curve (c-d). Figure 7. Frontal photography of the smile of a patient with lower lip asymmetry, resulting in a heterogeneous curvature of the lip (a-b). The rehabilitation was based on the horizontal, eyebrow, bipupilar and commissure reference lines (c), and not in the curvature of the lip, when building the incisal edge, obtaining the harmony with the face (d-e).

37

Figure 8a.

Figure 8b.

Figure 8a-b. Patient presenting parafunctional wear and subsequent flatening of the smile line.

the anterior superior teeth is not parallel to the curvature of the upper rim of the lower lip; (2) decreased display of the central incisor at rest; (3) reduction of interincisal angles (the incisal embrasure); and (4) an evidenced anterior negative space.27 (Figure 8) In addition to these highlights, there is a clear change within the height/width ratio of the clinical crown and loss of the opaque or opalescent halo in the case of attrition. The final sum of all aspects analyzed above is the determination of a smile with an elderly appearance. The shape of the incisal edges is a fundamental parameter. In middle-aged and elderly patients, the incisal edge shape is often a straight line or an inverted curve, which creates uniformity and an artificial leveling of the smile line. In this situation, the incisal embrasures are small or absent, which makes the incisal edge flat and contributes significantly to an unpleasant effect and an inevitable appearance of senile smile.14 In younger patients, the incisal edges are shaped in the form of a “seagull”, due to the relative dimensions of the original teeth. In this situation, the incisal edge of the lateral incisors is 0.5 mm to 1.5 mm above the straight line joining the most incisal point of the central incisors and canines.43 The digital facial bow proposed in Figure 9 objectively expresses the average facial lines, the nasal alae and the incisal edge with the patient smiling, proposing a simple analytical framework for assessing the smile and his relationship with the face, as well as facilitating the aesthetic planning of the patient.

38

Figure 9.

Figure 9.

Figure 9. Digital design of the facial bow in the photography of the face with patient smiling and displaying mid, nasal alae and incisal edge lines.

PROPORTION OF THE THIRDS OF THE FACE The evaluation of the facial thirds and the correct diagnosis of its changes greatly influence the decision for orthognathic surgery prior to the aesthetic rehabilitation. Remember that in this evaluation it is important that the lips to be relaxed for proper measurements. The face is divided into thirds that define an ideal symmetry which are formed by horizontal lines, as highlighted below: (Figure 10) 1. upper third: the hairline to the eyebrow line (above the eyebrows), corresponding to approximately 30% of the total length of the face; 2. middle third: the eyebrow line to the interalar line, corresponding to approximately 35% of the total length of the face; 3. lower third: the interalar line to the base of the chin, corresponds to approximately 30% to 35% of the total length of the face.

Figure 10.

Figure 10. Patient photography with lips at rest position with the tracings of the lines that divide the face into thirds, for analysis of horizontal ratio.

39

Figure 11b.

Figure 11a.

Figure 11c.

Figure 11d.

Figure 11.Patient presenting with decreased lower third; initial photo with tracings dividing the face into thirds (a) and initial photo of the smile showing tooth wear and loss of dimension (b). Post-rehabilitation photographs showing the established aesthetics (c) and harmony between the thirds of the face(d).

Figure 12a.

Figure 12c.

Figure 12b.

Figure 12d.

Figure 12e.

Figure 12. Patient with increased lower third as a result of vertical maxillary excess that declined to to submit to orthognathic surgery (a-b). Completion of the mock-up (c) guided the decision for periodontal cosmetic surgery associated with porcelain veneer veneers, with limited results, though harmonic and in accordance with the patient’s expectations (d-e).

40

The thirds are within a vetical range of 55 mm to 65 mm. Most often, the upper third is smaller than the others in normal faces; however, in some situations, the patient has degrees of baldness that prevent the use of this reference. For these common variations, the third is not important in the reference analysis. The increase in the lower third is often found in cases with vertical maxillary excess and Class II malocclusions. By analogy, the decrease in the same third is associated with vertical maxillary deficiency, mandibular retraction associated with deep bite and loss of vertical dimension. (Figure 11) This area of facial analysis is extremely important in the surgical orthodontic diagnosis and treatment planning. A classic example are patients with vertical maxillary excess, increased lower third, which are generally associated with gingival display greater than 3.0 mm. In this situation, the best approach is to carry out the orthognathic surgery prior to the aesthetic rehabilitative interventions, whether they are prosthetic or surgical-periodontal. However, the patient’s decision on whether or not undergo orthognathic surgery is sovereign and should be the focal point for proposals for new treatment modalities. The exclusion of orthognathic surgery as first choice encourages the establishment of a second treatment option, having the mock-up as facilitating instrument in that decision.This option involves performing periodontal cosmetic surgery associated with full ceramic veneers, with limited results.5 (Figure 12) However, and before the patient’s decision to refuse to undergo orthognathic intervention, the result, though limited, still promotes a pretty nice change and within the limits of technical feasibility available. Equality of the middle and lower third should not be used as the determining factor for changes in facial height. In fact, the lower third of the face is the most important for facial aesthetics, and thus the occurrence of variations in display of incisors and the interlabial space in the lower third are more important in the evaluation of equilibrium and equality of thirds..5,22 With the lips relaxed, the subnasal (Sn), the upper lip (Ls), the lower lip (Li) and soft tissues of the mento (Me) divided the length of the lower lip into thirds.6 (Figure 13) As a general rule, the length of the upper lip must be half of the length of the lower lip (skin and vermillion).56 The normal length of the Sn line to the upper rim of the Li is between 19 mm and 22 mm and involves the length of the upper lip, which is anatomically shorter (less than 18 mm, approximately), promotes increased interlabial distance at rest and consequently the display of the upper central incisors which is aesthetically desirable. This situation can not be confused as the vertical maxillary excess and increased lower third.5

Figure 13.

Figure 13. Frontal photograph showing length discrepancy of the relationship between upper and lower lips greater than1:2.

41

Figure 14a.

Figure 14b.

Figure 14c

Figure 14. Profile photography of patients with different classifications: normal (a), convex (b) and concave (c).

PROFILE VIEW The profile can be evaluated by joining three points (glabela, subnasal and pogonion) and the so formed internal angle. The overall harmony of the forehead, midface and lower third is evaluated with this angle. This analysis also becomes fundamental for the definition of conventional rehabilitative interventions or to the prior indication of orthognathic surgical procedures: (Figure 14) 1. normal: forms angle of approximately 170º; (Figure 14a) 2. convexity lower than 170 ° as a function of most posterior position of pogonion and suggests skeletal Class II. A Class II or convex profile patient, has little dominance of a central incisor; and (Figure 14b) 3. concave: greater than 170 ° as a function of most anterior position pogonion and suggests skeletal Class III. (Figure 14c) Other profile references are used to evaluate the harmony of the face and its consequences, such as the nasolabial angle. This angle is formed by the intersection of the anterior portion of the upper lip and subnasal columella. The factors to be considered in the planning to properly evaluate this angle are as follows: fformed by a line tangent to the base of the nose and another tangent to the outer edge of the upper lip, corresponds to 90º to 95º angle in males and 100° to 105° in females. This gender difference could be explained by the occurrence of the nose tip slightly pronounced in women. Still, whenever a patient has natural teeth or dentures labially inclined, the upper lip is also buccally projected, in a 1 to 0.4 ratio; ie for each 1.0 mm flaring of the teeth, the lip is buccally projected 0.4 mm. In females, this modification of the nasolabial angle provides a masculine profile.5,6 (Figure 15) 42

Figure 15a.

Figure 15b.

DENTOLABIAL ANALYSIS

Figure 15. Photograph of two patients showing the nasolabial angle and the difference between genders: female (a) and male (b).

LIPS The teeth, visible during wide smile and during speech, are framed by the lips. The orbicularis muscle of the lips lips joins superiorly to the base of the nose, to the nasolabial folds laterally and inferiorly the mentalis muscle. When compared to the upper lip, the lower a tendency has to be larger, full, broad and elastic.A vertical depression previously mentioned in this chapter, known as “philtrum”, is located in the upper lip and has great relevance in the analysis of the facial and dental midline. The philtrum length, measured from the subnasal angle to the lip vermillion, is 2.0 mm to 3.0 mm less than the height of the commissures to the horizontal line that touches the subnasal angle. This is attractive and desirable from the aesthetic point of view, and also determines increased display of the central incisor with the lips at rest. During smile, the lips should move uniformly with the horizontal plane, and therefore be parallel to the interpupillary line, which, remember, is the facial reference plane.22 In cases of irregularity of both sides of the upper lip during the smile, one should consider the possibility of adopting the horizontal plane as a reference. This scenario and its consequent relationship with a larger dental and gingival unilateral display becomes relevant for surgical planning and prosthetic rehabilitation, because sometimes having it as a reference and seeking harmony based on such disharmony promotes disastrous results from the aesthetic and biological point of view, obtaining tilted smiles. Variations the lip position may depend on ethnic and/or gender differences, especially in size, contour, shape and position in the range of natural dentition. These variations may occur depending on the shape, length, the activity of the lips and their support, which is based on the position of the alveolar process and teeth.27 The lip profiles may also be affected by the occlusal relationships (Class I, II and III). Thus, the E line, which connects the tip of the nose to the tip of the chin, should be evaluated, and the natural appearance 43

provided by the position of her upper lip, which is 4 mm shorter than her lower lip, 2.0 mm. Many variations are possible, but every lip position is found to be normal provided that it is located posterior to the line E.11 (Figure 16) The teeth and the alveolar process provide all the anatomical support of the lips, while the anterior superior teeth support the lower half of the upper lip. In fact, it is the tooth position, not the position of the incisal edge, which establishes the relationship to the upper lip, and this has been seen in studies that showed that in 70% of cases the support does not come from the incisal third, but from the remaining two thirds of the maxillary incisors. The maxillary teeth are the primary support of the upper lip, but this can vary depending on the type and shape of the lip. The position of the teeth have a greater effect in thin, prominent lips when they are compared with thick and retracted lips.10 (Figure 17) The correlation between lips, philtrum and central incisors is frequent and fundamental to establish the dominance of the centrals, which promotes a more pleasant aesthetics. As an example, bulky lips require longer and voluminous central incisors for proper display at rest.22 This condition favors positioning correcting the teeth in situations of tiltings with ceramic veneer veneers in which the patient does not accept undergoing orthodontic treatment without interference of the facial aesthetic outcome. In contrast, thin and short lips require finer central incisors, which prevents their overdisplay at rest.22 In this condition, it requires greater respect to morphology to be established, since the emergence profile to the three vestibular slopes, under the risk of changing the lip and facial aesthetics. DISPLAY OF THE ANTERIOR TEETH The lip position at rest is that in which the patient is in an upright and natural position of the head with jaw and lips relaxed. There are no tooth contacts, and a a slight interla-

Figure 16a.

Figure 16b.

Figure 17.

Figure 16. Patient photograph showing the ideal tracing of line E: with this line, the upper lip should be 4 mm below that line, and the lower, 2 mm below (a). In the second patient, the upper lip almost touches the line and the lower surpasses showing a mentus impairment (b). Figure 17. Patient with mock-up on the right hemiarch and without mock-up on the left hemiarch, which shows the difference in lip volume when there is an increase in the volume of anterior superior teeth.

44

bial separation is observed. To observe this position, the literature suggests the repeated speech of the letter “M”. When pronouncing that sound the patient touches the lips, which, when separated, return to the lip position at rest.22 Another possibility is the tip inwhich the patient blows softly with the lips sealed, and the end of this process also dictates the position of lips at rest. This reference condition is of utmost importance in defining the incisal length of the anterior teeth. It is also the position in which is diagnosed what is referred by the lay as “young smile” or “aged smile”. Such expressions emerged from the fact that there is less display of the upper teeth associated with aging, either by wear of tooth elements or the loss of perioral muscle tone. Such a reduction of display of superior-anterior teeth culminates in an display of the anterior-lower teeth. (Figure 18) In addition to this relationship with aging, there is a difference of dental display with lip position at rest between men and women. It is normal to have more dental display in females than in males.22,27 This is because women usually have shorter lips than men. The normal range is 1.0 mm to 5.0 mm.5

Figure 18a.

Figure 18b.

Figure 18c.

Figure 18d.

Figure 18e.

Figure 18f.

Figure 18. Photograph of patient’s face which does not expose the maxillary central incisors with lips at rest (ab) and smile photo (c). Facial photograph of the same the patient’s rehabilitated with porcelain veneer veneers without preparations from 26 to 16, showing display at rest compatible with gender and age (d-e) and the harmonious smile (f-h). Facial and artistic photographs by Dudu Medeiros.

45

Figure 18g.

46

Figure 18h.

47

Figure 19a.

Figure 19b.

Figure 19. Photograph of a male patient which shows the amount of exposure of the central incisors in optimal rest for men, about 1.91 mm (a). For women, this value reaches 3.4 mm (b).

Vig & Brundo71 reported that maxillary incisors are more displayed on average in women (3.4 mm) when resting than in men (1.91 mm) and that in young patients they are more visible than in middle-aged patients (3.37 mm against 1.26 mm).22 (Figure 19) FULL SMILE POSITION At full smile, some dental-labial features can be seen such as the gingival display (smile height); gingival balance of levels; harmonious gingival contour; the position of the gingival zeniths; the buccal corridor; and the occlusal plane relationship with commissure line and the incisal curvature. During smile, 57% of subjects exhibit up to the second bicuspid, and 20% until the first molar.18 According to Gurel,28 a pleasant smile is achieved when the angles of the mouth (labial commissure line) are parallel to the interpupillary line and the incisal plane, with the tips of the canine gently touching the lower lip. This touch should be added to the the incisal curve coinciding with the lower lip. SMILE LINE Defined as the lower edge position of the upper lip relative to the teeth and gingiva, the smile line defines the amount of tooth and gingiva exposed when the patient is smiling. It is related to greater mobility (muscle) of the lip and/or to its length and may be classified as follows:68 (Figure 20) • low: frequent in 20.5% of the population, the motility of the upper lip exposes up to 75% the length of the anterior teeth and no gingiva; • middle: frequent in 69% of the population, labial movement reveals 75% to 100% of the length of the anteriors and gingival papillae; • high: 10.5% frequent in the population, the anterior teeth are completely exposed during the smile and also a gingiva of variable length. At a frequency twice as large in women, it is suggested that this situation is due to the shorter the length of upper lip (average of 19.5 mm) in relation to men lip (average between 22 mm and 24 mm). 48

Figure 20a.

Figure 20b.

Figure 20c.

Figure 20. Facial photographs of three patients with different smile line heights and hence different degrees of exposure of the teeth and gingiva: Low (a), middle (b) and high (c). Photos by Dudu Medeiros.

The height of the smile is influenced by age and gender. The older the individual, the greater the tendency to present the low type.16 This information becomes clinically significant, since high smile lines tend to become middle with age, and low smiles become increasingly lower. In other words, there is a possibility of self-correction for smile “gingival” over time, and this not happens with low smile. According to Chang et al.13 and Cracel-Nogueira &Pinho,18 the average smile line is associated with more aesthetic smiles. Adding up these considerations, it is imperative that rehabilitative planning, especially surgical, to be based on this concept that the middle smile line is optimal and that is changeable over time. Thus, small distortions of high to middle smile lines will be compensated naturally and reach the optimal point through the years, which could, thereby promote less invasive therapies and quicker rehabilitation treatments. Gender also seems to influence the smile height. The literature shows that there is a greater tendency for women to have middle and high smile line, and men to have middle and low smile lines.55,59 The presence of a high smile line and disharmonic gingival contour suggests the clinical indication of periodontal cosmetic surgery to improve the results. In situations of low smile line, the gingival contour is not decisive and liable to influence the final smile. Disconsidering this correction depends on the acceptance of the patient to maintain the contour disharmony, even without obvious display during smiling. Sometimes even without direct interference on the displayed result, this imbalance is refuted by the patient and its correction needs to be considered and shown in the treatment planning. 49

When planning anterior rehabilitations one should consider that after the successful aesthetic rehabilitation treatment in anterior teeth, the maximum elevation of the upper lip during wide smile, may increase due to increased self-esteem of the patient. The upper lip line should not then be considered in the first evaluation as a reliable or immutable reference.28 BUCCAL CORRIDOR During the smile, not only are the teeth should be considered, but also the illusion of depth or grading effect provided by the negative space created by the buccal corridor. Such terminology is defined by the available space in the buccal aspect of the smile of the posterior teeth until the buccal mucosa. This depth effect is emphasized by the vestibular-palatal position of the maxillary canines.26,52,63 Remember that the relationship between the distance of the most lateral points of the canines and the distance between the angles of the mouth does not have strong influence on the smile aesthetics, but rather when evaluating the image as a whole. The buccal or lingua positioning of the bicuspids determines the appearance of a defect.31 (Figure 21) Overlooking the importance of this space brings smile disharmony, as in the case of positioning excessive buccal of rehabilitations in the posterior region. This can fill completely the buccal corridor and change the smooth and natural progression of smile. Conversely, an excessively broad buccal corridor also hinders the final outcome, by lack of buccal volume for premolars and molars.22 The observance of this initial clinical condition is determinant for the indication of ceramic veneer veneers in the posterior teeth, for the broad buccal corridor correction, because in case of installation for veneers in anterior superior teeth, there is an inevitable projection of the maxilla, which strongly highlights the initial defect shown. The opposite takes place when the indication is solely for the delivery of the ceramic veneers only of the anterior teeth.

Figure 21a.

Figure 21b.

Figure 21c.

Figure 21. Photographs patients who illustrating the three possible situations the buccal corridor analysis of: large (a) and narrow (b); and from two situations that change the natural progression of harmonious smile, and optimal (c).

50

GINGIVAL ANALYSIS

Ideally, the contour of the gingival margin outlined by the cervical levels of the maxillary canines and central incisors should be parallel to the incisal edge and the curvature of the lower lip.22 The gingival zenith is the most apical point of the gingival contour and usually is located distally to the long axis of the teeth. However, the exact distal positioning may vary due to the dental morphology, as well as by the shape of the cervical contour, determining the shape and size of the interdental papillae as well. The papillae, in turn, depends upon the presence of the diastema or even small interdental spaces, which is able of generating short and flat papillae, rather than the traditional long and inverted triangular shaped base. An aesthetically pleasing gingival contour occurs when the gingival zenith of the maxillary central incisor is symmetrical to the canine and ranges from 0.5 mm to 1.5 mm apical to the lateral incisor. In this conformation, the zeniths of the anterior superior teeth are characterized as the vertices of an imaginary triangle, which gives the balance of the gingival components. Lack of this harmony, verified by the absence of formation or inversion of this triangle, suggests the need for surgical correction of the tissue contour, in order to optimize the aesthetic result. The correct placement of the gingival margin will influence the tooth shape definitively.43 (Figure 22) Clinical situations in which the gingival margin of the central and canines are on the same plane, or when the margin of the canines is positioned slightly above the edge of the central incisors and the margin of the lateral incisors is below both the centrals and canines, are deemed harmonic conditions. If the level of the canine gingival margin is below the level of the central incisors or the edge of the laterals is higher than both teeth, this is to be considered a disharmonious condition with apparent reversal lines. (Figure 23) These variations in the gingival contours are visible particularly in patients with a high smile line completely exposing the anterior teeth along with a strip of gingiva of variable length of approximately 1.0 mm to 3.0 mm.37 The acceptability of this exposed gingiva ranges from 4 mm for lay people with a tolerance of up to 2 mm for clinicians.38 More recently, Kaya & Uyar35 revealed that the appeal of a smile is directly related to gingival display and consequently influenced by the smile arc, and the opposite is also true, as the smile arch is influenced by the gingival display. The results revealed that, in situations wherein the

Figure 22.

Figure 23.

Figure 22. Patient with optimal configurations of the gingival zenith, which greatly influence the final shape of the teeth. Figure 23. Demarcating zenith positions of anterior upper teeth, showing total bilateral disharmony and discrepancy with the aesthetic gingival principles.

51

amount of gingival display is insufficient, it is more appropriate to use more triangular arches (more closed). On the other hand, when the amount of display is excessive gingival, parabolical smile arches are more preferred. Situations where such a gingival display is greater than 3 mm are known as gingival smile. Its etiology is related to different factors: (1) passive incomplete or altered eruption; (2) excess gingival growth; (3) maxillary anterior or complete vertical excess (hyper-maxilla); (4) insufficient length of crown; (5) short upper lip; and (6) hyperactivity of the upper lip.41 Possible corrections for the gingival smile include periodontal surgery, orthodontic corrections, orthognathic surgery, and applicationof botulinum toxin (Figure 24) and application of orthopedic cement. The definition for the type of treatment will depend on the variety of existing medical conditions,50 the generated clinical consequences, and above all upon the patient’s compliance to the proposed treatment planning.

Figure 24a.

Figure 24b.

Figure 24c.

Figure 24d.

Figure 25a.

Figure 25b.

Figure 24. Patient with gingival smile and color and shape deficiencies of teeth (a). The use of botulinum toxin in the elevator muscle of the upper lip and nose wing (b) promoted reduction of the gingival smile (c). Final photograph of the patient with l installed aminates (d). Figure 25. Patient with thick lips and gingival smile (a) in which excess gingival exposure was eliminated by surgery to increase the clinical crown, and associated with dental bleaching (Power Bleaching®, BM4, Brazil), with predictable and satisfactory results.

52

Except for complex cases of vertical maxilla excess, the treatment of the gingival smile usually recommended and that should be firstly considered is clinical crown lenghtening through the removal of marginal support structures. (Figure 25) However, particular situations will advise the use of specific surgical procedures. In the presence of excessive soft and bone tissue, surgical techniques for such situations are gingivoplasty, osteotomy and osteoplasty, with total flap, mixed or without flap elevation, ie the flapless technique.33 This step is critical in determining the gingival contour, the zenith positioning and hence the dental morphology is be established after rehabilitation. Thus, the mock-up becomes an essential tool to guide the surgical process depending upon the advanced approval of the size and morphology of the tooth. (Figure 26) In some cases, the upper lip may not possess adequate bone support for the dynamics of the smile by shortening when it accommodates in the depression of the anterior maxillary process creates a broader smile or even during speech. In these situations, the literature has recommended the association of the clinical crown lenghtening surgery with orthopedic surgical cement to provide lip support and limit the elevation of the upper lip during smile.50 Such a situation can also be compensated for by the surgical reduction of bone volume of the anterior of maxilla process and the posterior regions in which the lip seats. The elimination of this accommodation position promotes only lip sliding in the maxilla, strongly controlling the gingival smile. Another relevant factor is to maintain the lip thickness with decreased bone volume when smiling. The lip, when accommodating itself within the anatomical depression invariably becomes thin by inversing to the full muscle movement.

Figure 26a.

Figure 26b.

Figure 26c.

Figure 26d.

Figure 26. Patients with thin lips and gingival smile represent a more complex condition (a), whose solution should be properly planned and tested through the use of a mock-up. In this case an indirect acrylic resin mock-up (b), showing the need for gingival and incisal lengthening. The same mock-up was also used as a surgical guide for achieving the clinical crown lenghtening surgery (c), whose result improved the gingival display, but was unable to solve it completely. The ceramic veneers complemented the rehabilitation lengthening to incisal, producing a more harmonious outcome (d).

53

The relationships and ratios of the anterior teeth determine an equilibrium for the aesthetic perception of a smile. Lombardi43 introduced to Dentistrythe application of the golden proportion. Although the concept of the golden proportion has fulfilled an important role, its application can not be rigid and should not be used to define a rehabilitation planning, disregarding individual modifying factors.4,20,29 The golden proportion produces results with narrower canines than desired, with less pleasant relationships from an aesthetic point of view.43,58 However, Murthy & Ramani50 revealed the possibility of applying this rule when considering and carrying out adjustments according to the ethnicity of the population. Thus, the authors define the ideal dimensions of the maxillary central incisors (CIs) as the starting point for planning being that they are more representative elements of the smile. There are different manners to determine the ideal width and length of the CIs. According to Fradeani,23 they should present an average width of 8.3 mm to 9.3 mm. Other researchers suggest possible relationships of dental measurements with facial and intraoral measures, in order to assist clinicians in this difficult task of determining the width of the anterior superior teeth.3,19,25 The width of the central, lateral incisors and canines are highly correlated with the interpupillary distance and the combination of interpupillary and interalar distances,30,32 along with the inter-commissure width and the distance between the medial corner of the eye (Intercantal).25 However, Strajnic, Vuletic &Vucinic67 reported not to rely on the application of parameters such as the intercantal distance and the interalar width, the same was shown by Hasanreisoglu et al.,29 who highlighted the need for correlating the width of the anterior superior teeth with the characteristics of race and gender. In the face of disagreements, the ease of use and relevant and desired individualized planning for each patient, the authors dictated as a rule using the interpupillary distance as a fixed and personal facial reference for determining the width of the central incisor.12 (Figure 27) The achievement of the width of the maxillary central incisor occurs by dividing the interpupillary distance by fixed factors, ranging from 6.6 to 7.2, defining the maximal and minimal ideal widths, respectively.12 The centrality for determining tooth width12,19 occurs due to the ease of determining the tooth height, since the smile height can be determined by the upper lip, which is a reliable anatomical reference. The relationship between the widths of the teeth is 100% for the CI; that of the lateral in relation to it is 74%; and the width of the canine is 88% relative to the central (may use 80% to 90%). These numerical mathematical relationships should not be overstated rigidly and with precision, due to the fact that there are variations in the literature caused by systematic errors during shooting. This statement explains the slight variation of the results from Preston,59 when comparing the relationship suggested above, with the lateral incisor width in relation to the CI (67%), and the width of the canine relative to the central (84%). Studies on tooth proportion have concluded that the length of the CI is 25% to 33% greater than its width. That is, to achieve the length it becomes necessary to multiply the width of CI by a coefficient of 1.25 to obtain the minimum length or by 1.33 to obtain the maximum acceptable length.14,15,22 (Figure 28) The centrals and canines have similar coronal heights 54

DENTAL ANALYSIS

WIDTH/LENGTH RATIO

Figure 28a.

Figure 27.

Figure 28b.

Operative Dentistry – Ideal Dimensions Central Incisor

Lateral Incisor

Canines

63

Lateral Width

Canine Width

Width of the Central Incisor

Width of the Central Incisor

C.I. Width

÷ 6,6 9,54

Length x Width - Ratio 100%

-25% (x0,75)

÷ 7,2 8,75

x1,33

x1,25

x1,33

x1,25

11,92 10,93

11,63

6,97

-0,5 to 1,5mm

-15% (x0,85)

7,9

With Diastemata

Check with D.I if it is greater the maximum acceptable refer to Orthodontics

Lateral Length

Canine Length

Equal to the Length of the Central Incisor

Equal to the Length of the Central Incisor

x

Minimum and maximum acceptable length of the central incisor

x+y+z= -0,5 or equal -0,5

Selected Design of the C.I. 9,3

Length 11,62

85%

0,5 or = CI

C.I. Width

12,68

Width

75%

-0,5 à 1,5mm

y

z

18,6 ÷ 2 =

9,3

Measurements For Wax-up

-0,5 à 1,0mm

-1,0

-0,5

INCISAL

CERVICAL

Final Value = 11,12

11,62 9,3

11,12

10,1 6,97

7,9

Final Value = 10,1

Figure 28c.

Table 1. Calculation for obtaining the width and length of the maxillary central incisors.

INTERPUPILLARY DISTANCE

÷ 6.6 = maximal width of the central incisor

x 1.33 = maximum length of the central incisor

÷ 7.2 = minimal width of the central incisor

x 1.33 = maximum length of the central incisor x 1.25 = minimal length of the central incisor

x 1.25 = minimal length of the central incisor

Figure 27. Photograph representing the correct way of measuring the interpupillary distance of the patient: head straight up, staring at a fixed point right in front, and the digital caliper placement at the center of both pupils. Figure 28. With the measurement of the interpupillary distance, two central incisor width values are obtained when dividing by 6.6 (a) or 7.2 (b), and two different lengths can be obtained from each of these values, when the width is multiplied by 1.25 or 1.33. Figurewith the patient’s calculations illustrating the chapter showing the obtaining of widths and lengths from the interpupillary distance,(c).

55

(range of about 0.5 mm) and a range of 1 mm to 1.5 mm longer than the lateral incisors.43,65 (Figure 29) In an ideal composition, two lines which join the cervicals and the incisal edges of the maxillary centrals and canines should include the laterals, ie ideally the laterals cannot break through those lines, neither by the gingival or incisal.14 Obtaining an ideal width/length aspect ratio is not always possible without orthodontic movement. Thus, one can rehabilitate clinical situations of the atresic arch without room for increasing the width of the teeth with alternatives such as the use of orthodontic separators, for a period of 24 h, promoting the creation of a space for the flaring of the teeth to be restored provisionally with composite resin, to maintain the space until the rehabilitation is completed. Regarding tooth crowding, Fradeani22 advocated that in rehabilitation without room for the six anterior superior teeth, the laterals should be narrowed. However, the authors have stated the ideal tooth to be modified for corrections of position and arrangement discrepancies, should always be the canine, because its distal portion is not visible. Another possibility to accommodate the teeth in the arch with little room is to rotate the laterals, always preserving the harmony of the dominant teeth of the smile, the central incisors. It is worth remembering that in both the above conditions, the dental anatomy would be wrong and not consistent with the natural anatomy.This means that attempting to solve aesthetic problems through compensations and changes in the anatomy of individual teeth is not always the ideal. Treatments correcting this initial condition, such as orthodontics, should be preferred. If this also is not possible, then the patient should be aware of the case limitations.28 (Figure 30)

Figure 29a.

Figure 29b.

Figure 29c.

Figure 29. From the ideal proportions of the central incisors of each patient it is possible to recreate shapes and sizes of the remaining teeth, creating a harmonic distribution, based on the actual measures obtained in the patient. With this new shaping a wax-up and mock-up can be made to explain to the patient all the possibilities for resolution of the case. In this case, direct composite resin mock-up was fabricated, along with smile (a), and intraoral (b) photographs. See the formation of the imaginary triangle of zeniths (c).

56

Panoramic view

Figure 30a.

Labial-palatal cross-sectional slices - Real size (1:1)

Figure 30b.

Figure 30c.

3D reconstructions Right buccal view

Occlusal view

Figure 30d.

Figure 30e.

Figure 30f.

Figure 30g.

Figure 30h.

Figure 30j.

Figure 30k.

Figure 30i.

Figure 30a-k. Surgical stage of the case shown in this chapter: clinical crown lenghtening, tooth extraction of #53 and fixture installation.

57

TOOTH TYPE The tooth type refers to form. According to Lombardi,43 choosing the shape of teeth for rehabilitation is based in compliance with the shape of the face of the patient. Other parameters are also used when choosing dental forms such as gender, personality and age.28 Thus, the first techniques to select tooth shape appeared in the late nineteenth century, influenced by the theory of the four moods.7,71 Based on the observation of physical and emotional characteristics, subjects were classified into one of the following moods: sanguine, phlegmatic, choleric or melancholic. The different tooth shapes corresponded to different moods.73 However, based on Williams’s work, the mood theory was discredited by the scientific community.72 Theoretically, the existence of a typical woman’s tooth may be assumed to be more rounded, such as ovoids, and a purely masculine tooth, square, as demonstrated by Burchett and Christensen.9 However, it seems there is no exact correlation between gender and tooth form because of its prevalence data may not be the rule, and there is no reason to state that these differences are easily noticeable from casual observation.8 The observation of a large number of natural tooth forms clearly demonstrates the countless variations of tooth forms and that these characteristics differ in the most diverse ways. Thus, for teaching purposes, there are three main types of tooth forms: ovoids, triangular, and squared.34,72 To better understand these forms one must know the morphology, the marginal ridges defined as determinants enamel ridges on the prominence and visualization of the teeth. Between the ridges, there is a flat area, especially in the maxillary incisors. At the proximal aspect of the ridges, regardless of lighting, shading occurs, from which the optical perception of the tooth volume is defined. For this reason, the use of articulated twin speedlights or still lighting for clinical shots is indicated, in order to highlight the marginal ridges through lateral illumination. Most often, a circular flash is unable to define the details of the tooth form with precision.28 Table 2 features the three formats. (Figures 31, 32 and 33)

Table 2. Characteristics of the most commonly found tooth shapes.

SHAPE

SQUARED

OVOIDAL

TRIANGULAR

Peripheral contour

Straigth

Rounded

Strait

Marginal ridges .

Sharp and parallel .

Smooth and converging to incisal and cervical

Prominent and converging towards the cervical

Developmental grooves .

Long mesial and narrower incisal base compared to the distal

Without sulcii .

Discrete concavity between crests .

Flat area

Greater and uniform

Greater in the middle third

Greater in the incisal third

Zenith

Distal to the crown long axis

Between middle and distal thirds

Central

Gingival contour .

Slightly rounded or flattened in the middle third

Completely rounded .

Triangular .

Shadow area

Small, uniform and clear transition to the plane area

Smaller in the middle third and smooth transition to flat area

Greater in the cervical third and quite clear transition to the flat area

58

Figure 31a.

Figure 31b.

Figure 31c.

Figure 32a.

Figure 32b.

Figure 32c.

Figure 33a.

Figure 33b.

Figure 33c.

Figure 31. The photograph represents a natural squared tooth (a) and a wax-up where the goal was to obtain a squared tooth shape (b) with its greater light reflection and minor shade area (c), causing the impression that the tooth is wider. Figure 32. Photography of a natural ovoid tooth (a) and wax-up of the same previous mouth with ovoid teeth (b), now presenting outline and smoother configuration with almost no shaded area (c). Figure 33. The natural triangular tooth is shown in Figure (a), and the same teeth from previous waxing represent now that format, showing the change of the flat area (b), shape of the crest and the zenith position (c).

Due to the subjectivity of tooth shape and numerous individual variations, the ultimate goal should be the making of the diagnostic wax and the completion of the mock-up, for the patient’s subsequent approval.43

59

PROXIMAL CONTACT AREAS IN THE ANTERIOR DENTITION The proximal contact area is the wide area where two adjacent teeth touch each other. Between the anterior maxillary teeth, the length of this area is not equivalent. According to Morley,48 proximal contact areas should ideally be of approximately 50% of the length of the central incisor and between both centrals; 40% between the central and the laterals; and 30% between the laterals and the canines. In a more recent study, the percent rule was suggested to be 40-30-20, which indicates the relationship between the anterior teeth where the largest contact area occurs between the central incisors (40), and the narrower contact which is seen between the lateral incisor and the canine (20).64 (Figure 34) The most incisal aspect of the contact area is named the point of contact. Such contact points move apically as we move toward the posterior region. However, this rule should also be individually analyzed and in accordance with the tooth morphology present or established for the rehabilitation. Squared teeth have longer contact area proximal than triangular teeth as well as point of contact more incisal while in triangular teeth it is positioned more towards the middle third in teeth ovoid. The contact area and the interproximal point of contact is also variable for rehabilitation of areas with diastema, especially with converging faces to incisal. In these situations, the interdental spaces (diastema) “camouflage” the observation of an aesthetic and more severe morphological discrepancies: the gingival papillae. They present to be shorter when compared to the ideal papillae and planned and format different from the ideal trian-

Figure 34.

Figure 35.

Figure 34. Schematic representation of the different contact areas found in the anterior superior teeth, showing proportional reduction from anterior to posterior. Figure 35. Schematic of the ideal size of the embrasures of the anterior teeth drawing: the cervical embrasures should decrease as we move away from the midline, while the incisal embrasures should increase in the same direction.

60

gular shaped; however, they have deeper gingival sulcus and greater tissue volume, which facilitates their handling during the interim phase and after the delivery of the ceramics. As discussed in Chapter 6.1, to minimize or eliminate the formation of black triangles or “black spaces”, the contact area should be extended as more cervically as possible; therefore, squared teeth, and especially ovoid are preferred for rehabilitating these situations. From the point of contact, two adjacent teeth diverge and form the incisal embrasures,28 the spaces found between a tooth and its adjacent in the incisal edge of anterior teeth. Its width is determined by the contact area of the proximal position, i.e., increasing in size as they move away from the midline. Ithis makes the incisal embrasure formed between both smaller in central incisors than in the central and lateral incisors, which, in turn, is smaller than the embrasure formed between the lateral and canine. On the other hand, the cervical embrasures decrease in their relative size as we move away from the midline.45,28,47 (Figure 35) The incisal embrasures can also affect the perception of the length, width and the incisal edge.A change in the incisal edge can provide a lowered or increased illusion of width. Worn teeth produce a loss of the incisal embrasures and create a short and wide tooth aspect. In diastema closure situations, an accurate job incorporating tooth morphology makes it necessary to create the optical illusion of narrower teeth. To this end, wide open incisal embrasures are manufactured, creating teeth which are preferably ovoid.28 Just like working with opened embrasures, the marginal ridges are manipulated as well as the area of light reflection to create the aspect of narrower teeth. (Figure 36)

Figure 36a.

Figure 36b.

Figure 36a-b. Diagram showing the displacement of edges, which gives from optical illusion narrower or wider teeth with teeth of the same width.

61

DENTAL AXES The gingival zenith, as described above, is the most apical point of the gingival contour which is usually distally located to the long axis of the teeth, depending upon the dental morphology. In this ideal anterior dental composition, the axial inclination of the anterior teeth normally produces coronal convergence and apical divergence from the midline. That is, the incisal third is inclined towards the mesial and the cervical region towards the distal aspect. The lateral incisors are inclined more distally in the apical direction than the centrals.22,45 Note that these are basic features in relation to the long tooth axis, and that the optical axis can change in accordance to the angle of observation. (Figure 37)

Figure 37b.

Figure 37a.

Figure 37c.

Figure 37d.

Figure 37e.

Figure 37. Patient presenting aesthetically compromising smile (a) with dental axes off the optimum standards(b). Diagram with the layout of the ideal tooth axes (continuous line) and present (dashed line) for this patient (c). Correcting these axes leads to a harmony of teeth with lips (37d) and each other (37e), providing greater beauty (c).

62

OPTICAL ILLUSION Through optical illusions created, contrasts can be enhanced and proportions can be distorted. In routine practice, misaligned teeth, slightly changed gingival contours and gingival recession occur very often. These variations may limit the use of a trustworthy rule, and where it is not clinically possible to establish the correct tooth proportion the clinician may create the illusion of having modified the tooth size without having actually carrying it out (illusion perception). In the marginal ridges above two major lines it is possible to differentiate to each other. The apex line of greater curvature lies well outside, and the second line, more central, internal from vault is the largest marginal ridge towards buccal. This marks the second line flat, strategic area for light reflection and disguises the appearance of anterior superior teeth. The external line of the vertex coincides in respect to the lateral edges of the shading called shaded area, from which the optical perception of the tooth volume is defined. The light that directly reaches the buccal surface between the ridges is reflected, while it reaches the outer areas of these lines it is deflected up and in this way is less noticeable. By modifying the orientation and arrangement of the internal lines of the ridges, the area of reflected light may be increased or decreased,21 which gives the visual aspect of broader or narrower teeth. (Figure 38)

Figure 38.

Figure 38. Diagrams representing the flat area based on position of the edges. The top drawing shows the vertical edge displaced to the proximal surfaces obtaining a large flat area and therefore more light reflection (contraindicated in patients with diastema). The bottom drawing represents the displacement of the edge more towards the medial third, offering an optical illusion of a narrower tooth.

63

According to Touati,69 in this manner, the tooth shape may also influence the perception of dimensions. To make thetooth apparently narrower, it is necessary to build a smaller flat area. In other words, there is least amount of space between both internal lines of the marginal ridge. This visual phenomenon occurs because, with the reduction of the flat area less dissipation of the light reflection takes place, which gives the optical illusion of a narrower tooth. Otherwise, by increasing the area, there will be greater light reflection and hence the aspect of a wider tooth. This analogy to light reflection also applies to surface texture and brightness of the teeth. The aesthetic rehabilitation and subsequent distribution of spaces must pass through the analysis of the amount of brightness present in the ceramics, as well as its texture, favoring the control of reflected light capable of creating the aspect of narrower or wider teeth. Finally, the projections of the internal vertex lines meet virtually at some point as they always converge in the cervical region of the tooth crown and create a smooth arch at the same height as the contralateral. Knowing these lines and their extensions allows for building rehabilitations with more predictable and more natural morphology.28 Decisively, there is the coincidence of the positioning of the gingival zenith and the cervical end of the distal marginal ridge on the maxillary central incisors, as in other anterior superior teeth. (Figures 39, 40 and 41)

Figure 39a.

Figure 39b.

Figure 39c.

Figure 39d.

Figure 39e.

Figure 40a.

Figure 40b.

Figure 39. Initial photograph for comparative analysis with the achieved result (a). Resolution of the clinical case illustrated in this chapter with intraoral photos and final smile, showing the beauty and harmony achieved with the rehabilitation (b-e). Figure 40. Design of the digital facial bow in the initial photo and the exact same bow in the final picture, which shows that the aesthetic goals based on facial references were achieved. Figure 41. Initial and final facial photographs of the case shown in this chapter. Photographs by Dudu Medeiros.

64

Figure 41a.

65

Figure 41b.

66

Figure 41c.

67

2. Ahmad I. Anterior dental aesthetics: dentofacial perspective. Br Dent J. 2005;199(2):81-8; quiz 114. 3. Al Wazzan KA. The relationship between intercanthal dimension and the widths of maxillary anterior teeth. J Prosthet Dent. 2001;86(6):608-12. 4. Ali FM, Jamani KD, Agrabawi J. Geometric and mathematical proportions and their relations to maxillary anterior teeth. J Contemp Dent Pract. 2006;7:62-70. 5. Arnett GW, Bergman RT. Facial keys to orthodontic diagnosis and treatment planning: part II. Am J Orthod Dentofacial Orthop. 1993;103(5):395-411. 6. Arnett GW, Bergman RT. Facial keys to orthodontic diagnosis and treatment planning: part I. Am J Orthod Dentofacial Orthop. 1993;103(4):299-312. 7. Berry FH. Is the theory of temperament the foundation of the study of prosthetic art? Dent Mag. 1906;1:405-13. 8. Brunetto J, Becker MM, Volpato CA. Gender differences in the form of maxillary central incisors analyzed using AutoCAD software. J Prosthet Dent. 2011;106(2):95-101. 9. Burchett PJ Jr, Christensen LC. Estimating age and sex by using color, form, and alignment of anterior teeth. J Prosthet Dent. 1988;59(2):175-9. 10. Burstone CJ. Lip posture and its significance in treatment planning. Am J Orthod. 1967;53(4):262-84. 11. Calamia JR, Levine JB, Lipp M, Cisneros G, Wolff MS. Smile design and treatment planning with the help of a comprehensive aesthetic evaluation form. Dent Clin North Am. 2011;55(2):187-209, vii. 12. Cesario VA Jr, Latta GH Jr. Relationship between the mesiodistal width of the maxillary central incisor and interpupillary distance. J Prosthet Dent. 1984;52(5):641-3. 13. Chang CA, Fields HW Jr, Beck FM, Springer NC, Firestone AR, Rosenstiel S, et al. Smile aesthetics from patients’ perspectives for faces of varying attractiveness. Am J Orthod Dentofacial Orthop. 2011;140(4):e171-80. 14. Chiche GJ, Pinault A. Artistic ans scientific principles applied to aesthetic dentistry: In: Chiche GJ, Pinault A, editors. Aesthetics of anterior fixed prosthodontics. Chicago: Quintessence; 1994. p. 13-32. 15. Chiche GJ, Pinault A. Aesthetics of anterior fixed prosthodontics. Hanover Park: Quintessence; 1996. 16. Cosendey VL. Avaliação do relacionamento entre o lábio superior e incisivos durante a fala e o sorriso [dissertação]. Rio de Janeiro: Universidade do Estado do Rio de Janeiro; 2008. 17. Peck S, Peck L, Kataja M. Some vertical lineaments of lip position. Am J Orthod Dentofacial Orthop. 1992;101(6):519-24. 18. Cracel-Nogueira F, Pinho T. Assessment of the perception of smile aesthetics by laypersons, dental students and dental practitioners. Int Orthod. 2013;11:432-44. 19. Dong JK, Jin TH, Cho HW, Oh SC. The aesthetics of the smile: a review of some recent studies. Int J Prosthodont. 1999;12(1):9-19. 20. Ellakwa A, McNamara K, Sandhu J, James K, Arora A, Klineberg I, et al. Quantifying the selection of maxillary anterior teeth using intraoral and extraoral anatomical landmarks. J Contemp Dent Pract. 2011;12(6):414-21. 21. Forster A, Velez R, Antal M, Nagy K. Width ratios in the anterior maxillary region in a Hungarian population: addition to the golden proportion debate. J Prosthet Dent. 2013;110:211-5. 22. Fradeani M. Aesthetic rehabilitation in fixed prosthodontics. Aesthetic analysis: a systematic approach to prosthetic treatment. Chicago: Quintessence; 2004. 23. Fradeani M. Evaluation of dentolabial parameters as part of a comprehensive aesthetic analysis. Eur J Esthet Dent. 2006;1(1):62-9. 24. Frush JP, Fisher RD. The dynaesthetic interpretation of the dentogenic concept. J Prosthet Dent. 1958;8:558-81. 25. Gomes VL, Gonçalves LC, Costa MM, Lucas BL. Interalar distance to estimate the combined width of the six maxillary anterior teeth in oral rehabilitation treatment. J Esthet Restor Dent. 2009;21(1):26-35. 26. Gomes VL, Gonçalves LC, Do Prado CJ, Junior IL, Lucas BL. Correlation between facial measurements and the mesiodistal width of the maxillary anterior teeth. J Esthet Restor Dent. 2006;18(4):196-205. 27. Gracco A, Cozzani M, D’Elia L, Manfrini M, Peverada C, Siciliani G. The smile buccal corridors: aesthetic value for dentists and laypersons. Prog Orthod. 2006;7:56-65. 28. Gurel G, Coachman C, Calamita M, Morimoto S, Paolucci B, Sesma N. The influence of tooth color on preparation design for veneer veneers from a minimally invasive perspective: case report. Int J Periodontics Restorative Dent. 2014;34(4):453-9. 29. Hajtó J. Regras de configuração. In: Hajtó J. Anteriores: a beleza natural dos dentes anteriores. São Paulo: Santos; 2008. p. 189-252. 30. Hasanreisoglu U, Berksun S, Aras K, Arslan I. An analysis of maxillary anterior teeth: facial and dental proportions. J Prosthet Dent. 2005;94:530-8. 31. Hoffman W Jr, Bomberg TJ, Hatch RA. Interalar width as a guide in denture tooth selection. J Prosthet Dent. 1986;55(2):21921. 32. Hulsey CM. An aesthetic evaluation of lip-teeth relationships present in the smile. Am J Orthod. 1970;57(2):132-44. 33. Isa ZM, Tawfiq OF, Noor NM, Shamsudheen MI, Rijal OM. Regression methods to investigate the relationship between facial measurements and widths of the maxillary anterior teeth. J Prosthet Dent. 2010;103(3):182-8. 34. Joly JC, Silva RC, Carvalho PFM. Reconstrução tecidual estética: procedimentos plásticos e regenerativos. São Paulo: Artes Médicas; 2010. 35. Kataoka S, Nishimura Y. Nature’s morphology: an atlas of tooth shape and form. Chicago: Quintessence; 2002. 36. Kaya B, Uyar R. Influence on smile attractiveness of the smile arc in conjunction with gingival display. Am J Orthod Dentofacial Orthop. 2013;144(4):541-7. 37. Kokich V. Aesthetics and anterior tooth position: an orthodontic perspective. Part III: Mediolateral relationships. J Esthet Dent. 1993;5(5):200-7. 38. Kokich VO Jr, Kiyak HA, Shapiro PA. Comparing the perception of dentists and lay people to altered dental aesthetics. J Esthet Dent. 1999;11(6):311-24. 39. Kokich VO, Kokich VG, Kiyak HA. Perceptions of dental professionals and laypersons to altered dental aesthetics: asymmetric and symmetric situations. Am J Orthod Dentofacial Orthop. 2006;130:141-51.

68

REFERENCES

1. Ahmad I. Anterior dental aesthetics: Dental perspective. Br Dent J. 2005;199(3):135-41.

40. Leong SC, White PS. A comparison of aesthetic proportions between the healthy Caucasian nose and the aesthetic ideal. J Plast Reconstr Surg. 2006;59:248-52. 41. Leong SCL, White PS. A comparison of aesthetic proportions between the Oriental and Caucasian nose. Clin Otolaryngol Allied Sci. 2004;29:672-6. 42. Levine RA, McGuire M. The diagnosis and treatment of the gummy smile. Compend Contin Educ Dent. 1997;18(8):757-62, 764; quiz 766. 43. Lombardi RE. The principles of visual perception and their clinical application to denture aesthetics. J Prosthet Dent. 1973;29:358-82. 44. Magne P, Belser U. Bonded porcelain restorations in the anterior dentition: a biomimetic approach. Carol Stream: Quintessence; 2002. 45. Malafaia FM, Garbossa MF, Neves AC, DA Silva-Concílio LR, Neisser MP. Concurrence between interpupillary line and tangent to the incisal edge of the upper central incisor teeth. J Esthet Restor Dent. 2009;21(5):318-22. 46. Matthews TG. The anatomy of a smile. J Prosthet Dent. 1978;39(2):128-34. 47. Miller EL, Bodden WR Jr, Jamison HC. A study of the relationship of the dental midline to the facial median line. J Prosthet Dent. 1979;41(6):657-60. 48. Morley J. A multidisciplinary approach to complex aesthetic restoration with diagnostic planning. Pract Periodontics Aesthet Dent. 2000;12(6):575-7. 49. Moskowitz ME, Nayyar A. Determinants of dental aesthetics: a rational for smile analysis and treatment. Compend Contin Educ Dent. 1995;16(12):1164-6. 50. Murthy BV, Ramani N. Evaluation of natural smile: Golden proportion, RED or Golden percentage. J Conserv Dent. 2008;11:16-21. 51. Naldi LF, Borges GJ, Santos LFE, Andrade RS, Batista DG, Souza JB. Aumento de coroa estético associado ao reposicionamento labial com cimento ortopédico. Rev Odontol Bras Central. 2012; 21(57):493-7. 52. Orce-Romero A, Iglesias-Linares A, Cantillo-Galindo M, Yañez-Vico RM, Mendoza-Mendoza A, Solano-Reina E. Do the smiles of the world’s most influential individuals have common parameters? J Oral Rehabil. 2013;40(3):159-70. 53. Parekh SM, Fields HW, Beck M, Rosenstiel S. Attractiveness of variations in the smile arc and buccal corridor space as judged by orthodontists and laymen. Angle Orthod. 2006;76:557-63. 54. Paris JC, Ortet S, Larmy A, Brouillet JL, Faucher AJ.Smile aesthetics: a methodology for success in a complex case. Eur J Esthet Dent. 2011;6(1):50-74. 55. Passia N, Blatz M, Strub JR. Is the smile line a valid parameter for aesthetic evaluation?: a systematic literature review. Eur J Esthet Dent. 2011;6(3):314-27. 56. Paula Jr. DF, Silva ET, Campos ACV, Nuñez MO, Leles CR. Effect of anterior teeth display during smiling on the self-perceived impacts of malocclusion in adolescents. Angle Orthod. 2011;81:540-5. 57. Perenack J. Treatment options to optimize display of anterior dental aesthetics in the patient with the aged lip. J Oral Maxillofac Surg. 2005;63:1635. 58. Pinho S, Ciriaco C, Faber J, Lenza MA. Impact of dental asymmetries on the perception of smile aesthetics. Am J Orthod Dentofacial Orthop. 2007;132:748-53. 59. Preston JD. The golden proportion revisited. J Esthet Dent. 1993;5:247-51. 60. Puppin FA. Avaliação quantitativa de medidas dento-faciais relacionadas à altura da linha do sorriso [dissertação]. Rio de Janeiro: Universidade do Estado do Rio de Janeiro; 2002. 61. Ricketts RM. Aesthetics, environment, and the law of lip relation. Am J Orthod. 1968;54(4):272-89. 62. Rodrigues CDT, Magnani R, Machado MSC, Oliveira Jr OB. The perception of smile attractiveness: variations from aesthetic norms, photographic framing and order of presentation. Angle Orthod. 2009;79:634-9. 63. Rufenacht CR. Fundamentals of aesthetics. Carol Stream: Quintessence; 1990. 64. Sarver DM, Ackerman MB. Dynamic smile visualization and quantification: Part 2. Smile analysis and treatment strategies Am J Orthod Dentofacial Orthop. 2003;124:116-27. 65. Stappert CF, Tarnow DP, Tan JH, Chu SJ. Proximal contact areas of the maxillary anterior dentition. Int J Periodontics Restorative Dent. 2010;30(5):471-7. 66. Sterrett JD, Oliver T, Robinson F, Fortson W, Knaak B, Russell CM. Width/length ratios of normal clinical crowns of the maxillary anterior dentition in man. J Clin Periodontol. 1999;26(3):153-7. 67. Strajnić L, Vuletić I, Vucinić P. The significance of biometric parameters in determining anterior teeth width. Vojnosanit Pregl. 2013;70(7):653-9. 68. Strub JR, Turp JC. Aesthetics in dental prothetics. In: Fischer J. Aesthetics and prothetics. Chicago: Quintessence; 1999. p. 11. 69. Tjan AH, Miller GD. The JG. Some aesthetic factors in a smile. J Prosthet Dent. 1984;51:24-8. 70. Touati B. Defining form and position. Pract Periodontics Aesthet Dent. 1998;10(7):800,802-3,806-7. 71. Vig RG, Brundo GC. The kinetics of anterior tooth display. J Prosthet Dent. 1978;39(5):502-4. 72. White JW. Temperament in relation to teeth. Dent Cos. 1884;26:113. 73. Williams JL. A new classification of human tooth forms, with special reference to a new system of artificial teeth. Dent Cos. 1914;56:627-8. 74. Young HA. Selecting the anterior tooth mold. J Prosthet Dent. 1954;4:748-60.

69

chapter 3

shade selection and reproduction in ceramic veneers Max Schmeling

blems of actors and actresses during footage at Hollywood.38 At that time, inextricably, there were also the first attempts at reproduction of tooth color. It was the beginning of Cosmetic Dentistry. After nearly a century, professionals from different specialties perform the process of selection and shade reproduction – by the direct or the indirect technique – with no formula which guarantees them complete predictability. For this reason several authors relate the aesthetic treatments to artwork, rather than to relate them to science. However, based on scientific evidence, we present in this chapter information intended to make the chromatic procedure more predictable, upon the underlying concepts of color, of optical characteristics of natural teeth and the main chromatic evaluation me-

INTRODUCTION

Ceramic veneers were introduced to Dentistry in the 1930s to solve aesthetic pro-

thods used in Dentistry. At the final part of the reading, the main information related to color reproduction of teeth with ceramic veneers will be described, and the main means of communication to the ceramist will be presented to guide the clinician in implementing

In order to having color, i the presence and the interaction of three fundamental factors s necessary: the light source, the object and the observer (Fig. 1). After it is emitted by a source and hit an object, the luminous energy may be reflected or transmitted to the eyes of the observer, responsible for capturing and the transformation of such physical energy into nerve impulses which shall be interpreted by the brain as a chromatic sensation. The need for cerebral interpretation, however, gives the visual observation method a subjective character, despite the standardization of the light source and of the object.8

PHYSICS OF COLOR

this important procedure.

Light source

Viewer Object Figure 1.

Figure 1. Light source, object and observer.

72

LIGHT SOURCE

Light is a form of electromagnetic energy, distinguished from radio waves or microwaves by the wavelength (Fig. 2). Although the human eye is continually exposed to all wavelengths present within the electromagnetic spectrum, only a small range between 380 nm and 700 nm (nanometers), called the “visible spectrum”, is able to stimulate photosensitive cells present in the retina and trigger the process of of color perception.35 The sunlight, also called natural light or white light contains all of the colors, as evidenced by Isaac Newton, in 1730, when dissociated a beam of white light into seven visible colors through the incidence in a prism. This luminous capacity plays a key role in the science of colors and, therefore, should be considered the first option in chromatic procedures. When this is not possible, we strongly recommend to use lamps that simulate natural lighting under ideal atmospheric conditions. According to the International Commission of Illumination (CIE, Commission Internationale de L’eclairage), there are several sources of light, each and everyone presents its characteristic color temperature, described in kelvin degrees (ºK). However, illuminants with a temperature of 2,856 ºK (“A Illuminant”) and 6,500 ºk (“D65 illuminant”) are the most commonly found in supermarkets and specialty shops, considered as basic sources (Fig. 3).11 The “standard A” illuminants show yellowish chromatic tendency, resembling a candle flame, and are therefore popularly

Violet

Indigo

Blue

Green

Yellow

Orange

Red

Ultraviolet

Infrared

400 nm

50 nm

600 nm

700 nm

Figure 2.

A-Illuminant

D65-Illuminant

2856 k

6500 k

Figure 3.

Figure 2.Visible spectrum of the electromagnetic field. Figure 3.Standard A illuminant (2,856 K) and standard D illuminant (6,500 K).

73

called incandescent. Because the the sum of the light spectrum wavelengths is its color temperature, illuminants these have low spectral amplitude and should not be used separately in chromatic procedures. On the other hand, “D standard” illuminants have bluish tendency, higher spectral amplitude and ultraviolet (UV) light wavelengths, being referred to as fluorescent. In fact, the light spectrum emitted by them is similar to the natural light and,

Reproduction of tooth shade with a restorative material is possible only due to a psychophysical phenomenon called metamerism, observed when objects having different physical and  chemical properties interact similarly with the luminous energy, in order to result in the same color appearance. These objects are called “metameric pairs”.6 In cosmetic dentistry, the pursuit for the formation of metameric pairs is imperative when trying to reproduce the tooth shade with a restorative material. Despite the different treatment techniques, either by a direct or indirect method, there are situations that can cause chromatic differentiation of the metameric pairs and aesthetic treatment failure. These situations, called “metameric failure”, may manifest in the object or the observer.41

METAMERISM

therefore, should be considered the first option when the latter can not used.30

Metameric failures manifested in the object, which could possibly occur after making the restoration, are usually associated with changing light source (Fig. 4). A common mistake is to perform the procedures of shade selection and reproduction under a halogen light reflector. In this condition, the restoration can perfectly blend to tooth structure, or the repair ceramic restoration can be perfectly accomplished by using a composite resin, but under a more intense source of light (eg daylight), different interactions may occur between the light, the tooth and the restorative material, resulting in the perception of color.23,26 To avoid this situation, as described above, selection and shade reproduction procedures require light bulbs with a broad and balanced spectrum light, simulating natural lighting under ideal conditions.

Figure 4a.

Figure 4b.

Figure 4a-b. Metamerism of the object. The patient has a ceramic veneer on tooth 21 photographed under different light sources (left, 2,856 K; right, 6,500 K). Note that under light source with richer spectrum, a small color difference between the restoration and the tooth can be perceived better.

74

Metameric failures from the observer can occur when the illuminating source and the object remains constant, with different observers. It is the result of the complex psychophysiological mechanism which begins with capture by the eye and is carried out in the cerebral interpretation of each observer. Thus, the color of a restoration can be satisfactory for the professional and his patient, and unsatisfactory for their relatives and friends.6,41 Solving that problem is feasible but costly. One alternative is by using electronic devices for measuring of color (instrumental observation). As we shall see later, the instrumental observation method is an important aid in the selection and dental shade reproduction for all levels of professionals, even though these instruments do not ensure that the metameric failure manifested in the viewer no longer occurs, due to the subjectivity of the final evaluation of color when carried out with the visual observation method. After a lot of training, the control of luminosity in the surgical ambient and the knowledge the restorative material possibilities, still it is up to professional strive in the procedure, asking for, whenever possible, for the patient’s and third parties’s opinion during the shade selection process. At the end of treatment, even in the face of aesthetic excellence, the patient can be instructed as to the potential expression of tiny metameric failures, by the impossibility of completely reproducing the same light interaction with different materials. Once having established the spectral quality, another factor of great importance related to the light source is the intensity with which the energy reaches our eyes. Similarly, insufficient light intensity complicates the chromatic evaluation, an exaggerated light intensity also impairs. The optimal intensity can be measured using a light output meter, called radiometer (Fig. 5), which should remain close to 100 candles (Watts). Such an intensity is responsible for promoting an adequate opening of the pupil diameter, key factor for proper selection and shade reproduction, and generally corresponds to a unit with 4 fluorescent lamps of 220 watts arranged 2 meters away from the object.1 Figure 5.

Figure 5. Lightmeter.

75

a century dental literature discussed and supported the three-dimensional classification of colors proposed in 1898 by the American artist Albert Munsell. In this system, colors can be expressed by the interaction of three dimensions, called hue, chroma and value.51 HUE Hue is the most recognizable dimension of color, as IT corresponds to the name of the color. It is the quality that distinguishes one color from another family, i.e. yellow from red, or green from blue (Fig. 6). Hue is also described as the main reflected wavelength, resulting from the interaction between the luminous energy and the object. In Dentistry is considered the least chromatic dimension, due to the small existing variation between tooth shades, which are limited to variations between shades of yellow and orange.

Figure 6.

Figure 7.

Figure 8.

Figure 6. Hue Figure 7. Chroma. Figure 8. Value.

76

THE THREE DIMENSIONS OF COLOR

In order to provide increased objectivity to the chromatic communication, for nearly

CHROMA Chroma is the degree of saturation, intensity, purity or amount of pigments present in a particular hue, making it impossible to compare this dimension among different hues (Fig. 7). In translucent bodies the chroma is strongly influenced by the thickness of the material.43 In natural teeth it varies from one tooth to another and between one region and another in the same tooth. VALUE Value is the most difficult dimension of the color of being identified and is the capability of light reflection of an object. The value scale is limited in its top end by the white color (high value), which represents the clearest possible color, and on its bottom end by the black color (low value), representing the lowest brightness which a color can display. Somewhere in between, there is an achromatic scale, made up of different shades of gray (Fig. 8). When considering shade selection and reproduction in Dentistry, value is the most important dimension, since small discrepancies in value are more easily recognizable than

TRANSLUCENCY

small differences in chroma and hue.

Human teeth have different degrees of translucency, which can vary according to the thickness of  enamel and dentin. Similarly, this also occurs with composite resin and dental ceramics. In other words, increasing the thickness of these tissues and materials increases their opacity and decreases their translucency. Defined as the relative amount of light transmitted through a material, the translucency can be translated as an intermediate position between the full blocking of light rays (opacity) and their total transmission (transparency). Therefore, translucent objects allow light to pass through them partially varying it  to a greater or lesser degree (Fig. 9).43 The chromatic evaluation in translucent bodies is significantly more complex than in opaque bodies. Hue, chroma and value are parameters found to be insufficient to describe accurately the optical effects observed in objects that allow for light transmission. For this

Incident light

Transmitted light

Transparency

Figure 9a.

Incident light

Transmitted light

Translucency

Figure 9b.

Incident light

Figure 9c.

Opacity

Figure 9a-c. Translucency.

77

reason, translucency is considered the fourth chromatic dimension applied to Restorative Dentistry. In this four-dimension concept, value remains as the most important dimension of color, and secondly the translucency.16 In addition to thickness, another factor that influences the translucency of the teeth is the surface texture.3 It concerns the surface appearance of the objects. In general, one can divide it into macro- and micro-textures (Fig. 10).5,16 Macro-textures are topographical variations found on enamel surface, as, for example, the ridges and development sulci, and are responsible for broad areas of light reflection. Micro-textures are formed by tiny alterations of the enamel surface, occurred by deposition of hydroxyapatite crystals, carried out by the ameloblasts during the formation of the tooth germ, which results in the formation of small parallel sulci, named perikymata. A perikymata-rich surface is responsible for creating diffuse reflection areas on the tooth surface and the consequent decrease of translucency.

Figure 10.

Figure 10. Surface texture.

78

COLOR DYNAMICS IN NATURAL TEETH

Teeth are formed by overlapping of enamel on dentin. A primary factor when studying dental polychromatism is the variation in thickness of these tissues as a function of physiological aging. In natural teeth, value or brightness is a enamel-related feature, while chroma and hue characterize dentin. Young people, less exposed to wear caused by dietary acids and toothbrushing, have thicker enamel than elderly people, and hence lighter teeth. As wear is enhanced and the thickness of the enamel layer decreases, the enamel translucency increases, which allows the chroma and the hue, features related to dentin, become increasingly evident. Thus, during the process of interaction of light with the dental tissues, enamel plays an important role acting as a filter, whose greater or smaller thickness accounts for brighter or less bright teeth (Fig. 11, 12 and 13).12,44 Enamel plays an important role acting as a filter, whose greater or smaller thickness accounts for brighter or darker teeth. Thus, in the cervical third, where enamel is thin, dentin color is only attenuated, and the chroma is high. In the middle third, where it is thicker, enamel is able to significantly filter the characteristics of dentin, making this region to present high luminosity and low saturation.19 In the incisal third, where dentin is thin or absent, hue and chroma of the tooth are replaced by translucency and opalescence effects, which will be discussed below.

Figure 11.

Figure 12.

Figure 13.

Figure 11.Teeth with high value - Young individuals. Figure 12. Teeth with medium value - adult individuals. Figure 13. Teeth with low value - Elderly individuals.

79

have different optical properties, that give teeth singular beauty, especially, the opalescence and fluorescence, respectively (Fig. 14). The opalescence is an optical property that occurs by scattering of the shorter wavelengths of the visible spectrum, making objects more bluish opalescent when viewed under reflected light, and more orange when observed under transmitted light.27 It is so called because it was firstly observed in opal stones (Fig. 15).40 All of the tooth naturally covered by enamel present opalescence. However, this property can be best seen in the maxillary central incisors in the form of bluish strip, located near the incisal edge, and named opalescent halo.15,50

OPTICAL PROPERTIES OF TOOTH TISSUES

In addition to presenting different degrees of translucency, enamel and dentin also

Figure 14.

Figure 15.

Reflected light

Transmitted light

Figure 14. Optical properties. The Figure shows three slices of mandibular  central incisor (0.4 mm). In the right slice under reflected light, we can see the bluish tendency of the shade of enamel. In the central slice it is noted that the orange shade is predominant, whereas the slice on the left is observed in low light environment, however rich in ultraviolet. Figure 15. Opal stone.

80

In addition to forming the opalescent halo, opalescence also gives rise to other optical phenomenon, named counter-opalescence, responsible for the orange appearance, which can be observed in the region of the mammelon tip in anterior teeth (Fig. 16).42,50 It occurs when waves of greater length which are generally transmitted through enamel, meet structures capable of reflecting them. When the light makes a reverse path across enamel, blue wavelength remains dispersed while longer lengths are transmitted, making dentin to appear orange. Because of its great aesthetic importance, the opalescence was considered by some authors a chromatic dimension.55 The tooth is a translucent structure, and therefore, its observation is subject to the influence of background contrast.25 Opalescence and counter-opalescence are also subject to this influence. Some authors found greater prominence of the opalescent halo when the maxillary central incisors were in disocclusion (seen under the dark background of the oral cavity). However, when they were in occlusion (seen with the mandibular incisors behind) The opalescent halo became less noticeable, as opposed to the counter opalescent characteristics, which were prominent (Fig. 17). By understanding the role and importance of the opalescence and counter-opalescence, we noticed that enamel contributes decisively in the expression of subtle variations of the hue observed in natural teeth.

Figure 16.

Figure 17.

Figure 16. Opalescence and counter-opalescence. Figure 17. influence of background contrast on opalescence and counter-opalescence.

81

Fluorescence is a luminescent phenomenon, i.e., which causes spontaneous emission of light by a process other than heating. To better understand it, we must remembers that the whole visible light is situated in a narrow band of the electromagnetic field, limited at the bottom end by the ultraviolet (UV) radiation and at the top end by the infrared radiation (both radiations invisible to the human eye).49 While most objects dissipate the luminous energy absorbed as heat, fluorescent objects re-emit part of this energy in a visible, longer wavelength, and in a higher speed 10-8 segundos. Among other luminescent phenomena we can highlight the phosphorescence. Phosphorescent objects differ from fluorescent by the speed of reemission of light energy. While fluorescent objects no longer display luminescence when the exposure to the radiant energy ends, phosphorescent objects can continue to present this feature for more than a day. This difference is explained when comparing the time required for the return of molecules excited by the radiant energy to its original orbital position.46 Although there is evidence that dentin and cementum exhibit red color when undergo the incidence of green light,24 fluorescence of the teeth is usually associated with blue-white color appearance, due to the impact of UV length emitted by black light commonly found in the dance floor and in nightclubs (Fig. 18). In such an environment, the incidence of UV length in a tooth restored with non-fluorescent material causes metameric failure, responsible for highlighting the restorative treatment, which, unlike the blue-white tooth, is perceived as colorless (Fig. 19).31 Fluorescence is an optical property which is present both in enamel and dentin, however, since it has been associated with the amount of organic matter, its intensity is three times higher in dentin than in enamel. This occurs due to the presence of collagen fibers, more precisely due to amino acids which help to build these fibers, such as tryptophan, pyrimidine and pyridinoline.21,37 Under natural light, fluorescence makes teeth brighter and shiny, and gives them “internal luminescence”.28 Despite the fact that the fluorescence of enamel is less than the fluorescence of dentin, its observation has been described as an effective alternative to initial diagnosis of caries due to the low fluorescent intensity of carious enamel when compared to sound enamel.53 When

Figure 18.

Figure 19.

Figure 18. Natural teeth observed in low light environment, however rich in ultraviolet. Figure 19. Tooth with non-fluorescent restoration observed in low light environment, however rich in ultraviolet.

82

human dentin was irradiated with light in the range of 365 nm with a fluorescence peak located in 440+/-10 nm was observed.17 According to the study by Matsumoto, Kitamura & Araki (1999), the physiological aging process increases the intensity of dental fluorescence due to a biological and thermal mechanism which acts on dentin.29 This result is in line with the changes of enamel resulting from physiological wear, which becomes thinner and more translucent over time, which allows for better visualization of the underlying dentin fluores-

SHADE GUIDES

cence.

Although the subjectivity of the visual observation method is proven in several studies, to visually compare the natural tooth with artificial shade guide is still the primary means of shade selection used in Dentistry. The first shade guide, with 60 chromatic samples, was created by Clark in 1930.10 Since then, several studies have been performed to optimize its clinical application, but without significant changes.35 Currently, Vitapan Classical® (VC - Vita Zahnfabrik, Bad Säckingen, Germany) and 3D-Master Vita® (V3DM – Vita Zahnfabrik, Bad Säckingen, Germany)the most popular chromatic scales are considered. From a few differences presented by these scales, the difference in the arrangement of their chromatic samples stands out - in the first range it is performed in groups of hues, while in the second one, it takes place in groups of value.45 Formed in 1950, the VC shade guide (Fig. 20) has gained popularity to serve as the chromatic standard for ceramicsystemsfrom different manufacturers.7 This shade guide has its chromatic tabs in four shades groups: A (brown), B (yellow), C (gray) and D (red). Different degrees of saturation (chroma) can be observed for the same hue expressed by numbers. Increasing number corresponds to increased hue saturation. Thus, the hue has five chromatic intensities (A1, A2, A3, A3,5, A4) the hues B and C show four (B1, B2, B3 and B4; C1, C2, C3 and C4), while the hue D has only three (D2, D3 and D4).

Figure 20.

Figure 20. Vita Classical® shade guide (Vita Zahnfabrik, Bad Säkingen, Germany).

83

For decades, the VC scale was considered among a reference shade guides, although the earliest studies also have been described problems regarding its use. Among these problems, there is inconsistency of the chromatic coverage range, which is characterized by loss of clinical time or impossibility to obtain the ideal chromatic sample.33,39 According to other studies, the A and B hues of this scale are present in most of natural teeth.12 The difference in shape and structure and of the teeth and the samples and the chromatic difference between samples of the same designation in the same brand scales are also often problems described. The small variation among dental shades and ocular physiology (which gives greater ease to detect minor variations of value than small variations of chroma and hue) made value the main dimension of color in Restorative Dentistry. To adapt to this new concept, some authors have suggested that VC scale tabs to be reordered according to the value (B1, A1, D2, A2, B2, C1, C2, D4, D3, A3, B3, A3,5, B4, C3, A4, C4).According to these authors, reordering tabs from the lighter color to the darker color provides a monodimensional evaluation system, which favors checking the correct color, saving clinical time and easier communication with the potter.32 The V3DM shade guide (Fig. 21), developed in 1998, presents its chromatic tabs arranged in five groups, according to the value. According to the manufacturer, unlike its predecessor, developed empirically, this shade guide was designed to meet modern aesthetic concepts. It features 26 chromatic tabs distributed in five groups designated by numbers (1, highest value; 5, lowest value). Selecting value consists of the first step of its use. Then the chroma selection must be made within the selected group value. In the groups of value 2, 3 and 4, there are three columns of chromatic tabs with the letter M (middle), L (yellowish) and R (reddish). The selection of the chroma must be initially carried out in the column of letter M. These letters represent the hue, the last step of shade selection. At that point the clinician should evaluate the tooth the existence of reddish or yellowish tabs than that presented by the tab of column M.

Figure 21.

Figure 21. Vita 3D-Master® shade guide (Vita Zahnfabrik, Bad Säkingen, Germany).

84

Several studies have reported the optimal distribution of guide tabs V3DM compared to other shade guides.36 According to these studies, this shade guide offers greater coverage and uniformity of tabs’ distribution, allowing for greater precision and easier shade selection.Another study, however, showed that this shade guide, although more uniform than the others, also presents chromatic gaps and limitations. Recently, Paravina evaluated the clinical performance of shade guides by comparing VC, V3DM and a new shade guide, developed based on the V3DM shade guide (Vita Linear Guide 3D Master® – Vita Zahnfabrik, Bad Säckingen, Germany). The results showed that the new shade guide achieved the highest efficiency, which demonstrates the continuous evolution of the shade guides

INSTRUMENT SHADE EVALUATION

and the inconclusive nature of the subject.34

In the instrumental shade matching, the devices carry out the observation and registration of the shade mathematically, providing reliability to the method.9,13,18 This can be achieved by the use of spectrophotometers, colorimeters and digital computer analysis. Spectrophotometers are devices used to measure the color of an object by their reflected wavelengths (Fig. 22). This record is obtained in the three-dimensional coordinate of the CIELab system. The L* axys indicates the achromatic coordinate or brightness of the object, with values from 0 (absolute black) to 100 (full white). The a* and b* axes indicate the chromatic coordinates, that present the three-dimensional positioning of the object in the color space and its direction. The a* axis is the amount of red (a* positive value), or green (a* negative value). The b* axis is the amount of yellow (positive b * value) or blue (negative b * value).47 When the values of a * and b * axes come closer to the zero, representing an achromatic area based in the value scale. Currently, some spectrophotometers also have capacity to evaluate tooth color according to shade guides, upon prior calibration of the device.

Figure 22.

Figure 22. Vita Easyshade® spectrophotometer (Vita Zahnfabrik, Bad Säkingen, Germany).

85

Furthermore, colorimeters perform color evaluation from reflected wavelengths, recording the results in three chromatic axes (X, Y, Z tristimulus or Cielab).22,48 Several studies in the literature about color of natural teeth were performed with this type of device, which demonstrated reproducibility in studies performed both in vitro and in vivo.13,18 When these comparisons are made with computerized digital imaging support, the results demonstrate to be promising, but inconclusive for some authors, who suggest the need for

The excellence of the optical properties associated to extremely conservative preparations made ceramic veneers a more popular treatment alternative. The color of treatments carried out with ceramic veneers is a result of viewing the light interaction with the ceramic veneer, with resin cement and the supporting substrate which may be formed by dental tissue and/or restorative material. When performing planning of these restorations, one must consider the primary chromatic influence of the substrate. Therefore, a big difference between the initial color of the substrate and the desired final color is a great restorative challenge. So it is up to the ceramic veneer and the resin cement the roles of neutralizing the color of the substrate and determining the final color of the restoration.14,52 Ceramic veneers are manufactured with varying thicknesses, which may vary from 0.3 mm to 1.5 mm, having varying degrees of translucency. Generally, increasing the thickness of the ceramic veneer is proportional to the decrease of translucency, which increases the influence of the veneer and reduces the influence of the resin cement on the final chromatic result.14 In addition to vary according to the thickness, the color of the veneers may also vary according to the manufacturer, chemical composition, particle size and mode of fabrication.4,20 Resin cements, in turn, are available in different shades and are critical to the success of restoration.2 Unfortunately, there are various systems of resin cements that have different characteristics of color and translucency for their respective shade tabs. Thus, it is strongly recommended to know the possibilities and limitations of the resin cement for a successful aesthetic treatment. The shade selection protocol differs according to the type of restoration to be fabricated. However, the observation and identification of the characteristics and optical effects should also be recorded. When color selection and reproduction are performed by the same individual, the process becomes more simple, dynamic and reliable. This happens when the restorations are fabricated with direct composite resin. For indirect restorations, the eyes conducting the shade selection are often not the same participating in confection of the restoration. Therefore, the step of color communication to the laboratory is extremely important in the aesthetic success of the restorations. Shade guides are essential for communication of the color dimensions, It is utterly important that the shade guide used for selecting the color in the office is the same used by the ceramist in the laboratory. The shade guides, as described, do not provide all of the features to be reproduced and may be used in conjunction with evaluation tools, chromatic maps and a suitable photographic documentation. 86

SHADE SELECTION FOR CERAMIC VENEERS

further investigation.

In the chromatic maps, one should highlight the subtleties where stains and characterizations should be located and designed.55 The photographic documentation generates more information than any verbal and written description. Photographs with the shade guide in position and different color options help in answering questions and, when viewed in black and white, a lot of help in the correct value selection. The hue or chroma should be recorded photographically, with a choice of three teeth of a shade guide touching the incisal edges of the natural tooth, side by side. The central option should be alternatively selected as the ideal, and the other two must have a chroma higher and one chroma lower. Is it possible to also record the translucency characteristics through photographs with moist teeth and a black background. During the evaluation of tooth shade the following characteristics should be identified and replicated in descending order of importance: (1) shape, (2) topography and surface texture, (3) value, (4) translucency, (5) chroma e (6) hue.5,54 This order is based on the fact that differences in shape, surface morphology, value and translucency may be perceived at greater distances than those of hue and chroma. Logically, the correct reproduction of a characteristic of a higher order of importance will not compensate for errors in the reproduction of less relevant factors, but it will lessen the perception of small differences, especially to untrained eyes.

87

2. Alqahtani MQ, Aljurais RM, Alshaafi MM. The effects of different shades of resin luting cement on the color of ceramic veneers. Dent Mater J. 2012;31(3):354-61. 3. Baratieri LN, Araújo JR, EM, Monteiro JR S. Composite restorations in anterior teeth: fundamentals and possibilities. New York: Quintessence; 2005. 4. Barizon KY, Bergeron C, Vargas MA, Quian F, Cobb DS, Gratton DG, et al. Ceramic materials for porcelain veneers. Part II: Effect of material, shade and thickness on translucency. Prosthet Dent. 2014;112(4):864-70. 5. Belli RH, Baratieri LN. Cor: fundamentos básicos. In: Baratieri LN, et al. Soluções clínicas: fundamentos e técnicas. São José: Ponto; 2008. cap. 1, p. 25-51. 6. Billmeyer and Saltzman’s principles of color technology. 3rd ed. New York: John Wiley Sons; 2000. 7. Brewer JD, Wee A, Seghi R. Advances in color matching. Dent Clin N Am. 2004;48(2):341-58. 8. Chu SJ, Devigus A, Mieleszko AJ. Fundamentals of color: shade matching and communication in aesthetic dentistry. Chicago: Quintessence; 2004. 9. Chu SJ, Tarnow DP. Digital shade analysis and verification: a case report and discussion. Pract Proced Aesthet Dent. 2001;13(2):129-36. 10. Clark EB. The Clark tooth color system. Parts 1 and 2. Dental Magazine and Oral Topics. 1933;50:139-51. 11. Comission Internationale de L’Eclairage. Colorimetry, official recommendations of the international commission on illumination. Paris: Bureau Central de la CIE. Publication CIE No. 15 (E1.3.1); 1971. 12. Dietschi D, Ardu S, Krejci I. A new shading concept based on natural tooth color applied to direct composite restorations. Quintessence Int. 2006;37(2):91-102. 13. Douglas RD. Precision of in vivo colorimetric assessments of teeth. J Prosthet Dent. 1997;77(5):464-70. 14. Dozic A, Tsagkari M, Khashayar G, Aboushelib M. Color management of porcelain veneers: influence of dentin and resin cement colors. Quintessence Int. 2010;41(7):567-73. 15. Duarte Jr S. Opalescence: the key to natural aesthetics. Quintessence Dent Technol. 2007:7-20. 16. Fondriest J. Shade matching in restorative dentistry: the science and strategies. Int J Periodontics Rest Dent. 2003;23:46779. 17. Foreman PC. The excitation and emission spectra of fluorescence components of human dentine. Arch Oral Biol. 1980;25(10):641-7. 18. Goldstein GR, Schmit GW. Repeatability of a specially designed intraoral colorimeter. J Prosthet Dent. 1993;69(16):616-9. 19. Hasegawa A, Ikeda I, Kavaguchi S. Color and translucency of natural central incisors. J Prosthet Dent. 2000;83(4):418-23. 20. Heffernan MJ, Aquilini SA, Diaz-Harnold AM, Haselton DR, Stanford CM, Vargas MA. Relative translucency of six all-ceramic systems: core and veneer materials. J Prosthet Dent. 2002;88(1):10-5. 21. Hoerman KC, Mancewicz SA. Fluorometric demonstration of tryotophane in dentin and bone protein. J Dent Res. 1964;43:276-80. 22. Johnston WM, Kao EC. Assessment of appearance match by visual observation and clinical colorimetry. J Dent Res. 1989;68(5):819-22. 23. Kim SH, Lee, YK Lim BS, Rhee SH, Yang YC. Metameric effect between dental porcelain and porcelain repairing resin composite. Dent Mater. 2007;23(3):374-9. 24. Kvaal S, Solheim T. Fluorescence from dentin and cementum in human mandibular second premolars and its relation to age. Scand J Dent Res. 1989;97(2):131-8. 25. Lee YK, Lim BS, Kim CW. Difference in the colour and colour change in dental resin composites by the background. J Oral Rehabil. 2005;32(2):227-33. 26. Lee YK, Powers, JM. Metameric effect between resin composite and dentin. Dent Mater. 2005;21(10):971-6. 27. Lee YK, Yu B. Measurement of opalescence of tooth enamel. J Dent. 2007;35(8):690-4. 28. Magne P, Belser U. Bonded porcelain restorations in anterior dentition: a biomimetic approach. Chicago: Quintessence; 2003. 29. Matsumoto H, Kitamura S, Araki T. Autofluorescence in human dentine in relation to age, tooth type and temperature measured by nanosecond time-resolved fluorescence microscopy. Arch Oral Biol. 1999;44(4):309-18. 30. Melo TS, Kano P, Araújo JR E. Avaliação cromática em odontologia restauradora. Parte 1: O mundo das cores. Clín – Int J Braz Dent. 2005;1(2):96-105. 31. Miller MB. Composite resin fluorescence. J Esthet Restor Dent. 2004;16:335. 32. O’Brien WJ, Groh CL, Boenke KM. One-dimensional color order systems for dental shade guides. Dent Mater. 1989;5(6):3714. 33. Paravina RD. Color in dentistry: match me, match me not. J Esthet Restor Dent. 2009;21(2):133-9. 34. Paravina RD. Performance assessment of dental shade guides. J Dent. 2009;(1): e15-20. 35. Paravina RD, Powers JM. Aesthetic color training in dentistry. St. Louis: Elsevier/Mosby; 2004. 36. Paravina RD, Powers JM, Fay RM. Color comparison of two shade guides. Int J Prosthod. 2002;15(1):73-8. 37. Perry A, Biel M. Comparative study of the native fluorescence of human dentin and bovine skin collagen. Arch of Oral Biol. 1969;14(10):1193-211. 38. Pincus CL. Building mouth personality. A paper presented at California State Dental Association; 1937. San Jose, California. 39. Preston JD. Current status of shade selection and color matching. Quintessence Int. 1985;16(1):47-58. 40. Primus CM, Chu CCY, Shelby JE, Buldrini E, Helcle CE. Opalescence of dental porcelains enamels. Quintessence Int. 2002;33(6):439-49. 41. Schmeling M. Como evitar falhas metaméricas nos procedimentos restauradores. Clín - Int J Braz Dent. 2010;17:8-10. 42. Schmeling M, Maia HP, Baratieri LN. Opalescence of bleached teeth. J Dent. 2012;(1):e35-39. 43. Schmeling M, de Andrada MAC, Maia HP, Araújo EM. Translucency of value resin composites used to replace enamel in stratified composite restoration techniques. J Esthet Restor Dent. 2012;24(1):53-8.

88

REFERENCES

1. Ahmad I. Three-dimensional shade analysis: perspectives of color. Part 2. Pract Proced Aesthet Dent. 2000;12(6):557-64.

44. Schmeling M, Meyer-Filho A, de Andrada MAC, Baratieri LN. Chromatic influence of value resin composites. Oper Dent. 2010;35(1):45-9. 45. Schmeling M, Sartori N, Monteiro Jr. S, Baratieri LN. Color stability of shade guides after autoclave sterilization. Int J Periodontics Restorative Dent. 2014;34:689-93. 46. Schmeling M, Sartori N, Perucchi LD, Baratieri LN. Fluorescence of natural teeth and direct resin composite restoration: seeking the blue aesthetics. Am J Dent. 2013;3:100-11. 47. Schmeling M, Vieira LCC, Maia HP, Lopes GC. Resinas compostas para esmalte clareado podem diminuir a luminosidade do substrato nas técnicas restauradoras estratificadas. Clín – Int J Braz Dent. 2010;6(1)78-85. 48. Seghi RR, Johnston WM, O’Brien WJ. Performance assessment of colorimetric devices on dental porcelains. J Dent Res. 1989;68(12):1755-9. 49. Sensi LG, Marson FB, Hawerroth T, Baratieri LN, Monteiro S. Fluorescence of composite resins: clinical considerations. Quintessence Dent Technol. 2006;29:43-53. 50. Sensi LG, Araújo FO, Marson F, Monteiro Jr S. Reprodoucing opalecent and counter-opalescent effects with direct resin composites. Quintessence Dent Technol. 2007;4:47-50. 51. Sproull RC. Color matching in dentistry. Part 1: The three-dimensional nature of color. J Prosthet Dent. 1973;29(4):416-24. 52. Stevenson B, Ibbetson R. The effect of the substructure on the colour of samples/restorations veneered with ceramic: a literature review. J Dent. 2010;38(5):361-8. 53. Sundstrom F, Frederiksson K, Montan S, Hafström-Bjorkmanu, Strom J. Laser-induced fluorescence from sound and carious tooth substance: spectroscopic studies. Swed Dent J. 1985;9(2):71-80. 54. Terry DA, Geller W, Tric O, Anderson MJ, Tourville M, Kobashigawa A. Anatomical form defines the color: function, form and aesthetics. Pract Proced Aesthet Dent. 2002;14(1):59-67. 55. Vanini L, Mangani FM. Determination and communication of color using the five color dimensions of teeth. Pract Proced Aesthet Dent. 2001;13(1):19-26.

89

chapter 4

aesthetic rehabilitation planning Paula de Carvalho Cardoso | Rafael de Almeida Decurcio | Ana Paula Magalhães | Marcus Vinícius Perillo

Contemporary Restorative Dentistry has an increased demanded for, comprehensive results, and not for the individualized treatment of dental elements. Whether by general information, or by social imposition, patients aim both aesthetically pleasing and natural as well as physiological and mechanically sound results. Assuming a leading role, bleaching therapy, adhesion processes and restorations with ceramic veneers have opened the door to a variety of dental treatments that improve appearance, usually by reversing signs of aging and offering predictability and longevity for aesthetic and functional rehabilitation. Understanding the expectations of patients is critical in order for the dentist to develop a treatment plan that is not only healthy for the dental tissues but also aesthetically satisfying. Generally, patients may not be able to identify their needs in more than a few words, in which their main complaints are stated. Thus, the clinician should decide when these expectations can be met.3 The procedures described below are tools to guide the dentist when planning that aims to achieve accurate and predictable results for Operative Dentistry

With the advent of digital photography the dentist has acquired a new method for communicating with the patient which includes images to demonstrate all of the conditions diagnosed, immediately after obtaining them. In addition, with the incorporation of these images became possible treatment options also to further show what has just been explained and perhaps even exemplified with cases of other patients may be used.19 Now, in a few minutes, is possible to show, in the photo of the patient, for example, a preview of the tooth bleaching results, lengthening or shortening the teeth, to demonstrate the possible results that would be obtained with orthodontics or ceramic veneers.8 Recently, digital planning has become an important tool to introduce the patients to all of the treatment possibilities that may be carried out based on ones initial conditions. The expertise of facial and dental aesthetic principles and digital technology tools, like Power Point® software (Microsoft Office, Microsoft, USA) and Keynote® (Apple Inc., USA), allow for the planning of the possible treatments with predictability and security, as well as communicating in advance with the patient and the dental lab about the possibilities.8 (Fig. 1). A complete analysis of the patient’s function as well as their subjective expectations is most important in addition to the aesthetic planning.5 For proper rehabilitation, the aesthetic planning it is necessary to integrate aesthetic concepts, in order to obtain harmony between ones facial aesthetics and dentofacial composition which include the lips and smile, with their dental composition, which relates more specifically to the size, shape and position of ones teeth and their relationship with the bone alveolar as well as gingival tissue.5 The details to be observed during these analysis were presented in Chapter 2 of this book, and here will be analyzed using the photographs obtained.

92

AESTHETIC REHABILITATION PLANNING

and Rehabilitation.

Figure 1.

PHOTOGRAPHY IN DENTAL CLINICS

Figure 1. Digital resources available to perform the digital aesthetic rehabilitation planning. It is possible to develop digital analysis of the work (Keynote, Apple, USA) and obtain important data to the development of the treatment. In this photo, for example, it is clear that the digital planning smile only is valid for the length and width of the central incisors (green), because they are bidimensionally positioned facing the viewer. For all remaining teeth (lateral incisors and canines - dotted lines), the trace is valid/functional for length, however for width is simply a graphic complement, null, given the rotation of these teeth in the arch, which prevents the accuracy of the digital demonstration.

The modern world is heading towards speed and convenience, people are seeking as much information in the shortest time. In this context, images have a key role, for carrying valuable information and without the need of words, transmitting them jointly with emotions and desires. A well taken image or photograph may add a more deep reflection and be able to persuade faster than words, by eliminating an unnecessary verbal analysis. Photography is not only used for professional documentation and legal security, it has become an indispensable tool in Cosmetic Dentistry  by offering images that capture a patient’s instantaneous emotion and further help the patient to make a decision.22 Allied to clinical and radiographic examination and study models, facial, dento-labial and intraoral photographs are used as an auxiliary in diagnosis, and essential in achieving an individualized aesthetic treatment planning with several specialties, integrating form, function and biology. Photographic images, with a static character, allows for a more detailed analysis of the face and smile, and, through further magnification, which are impossible to be seen with naked eye. Thus, it is also an excellent means of communication with the patient and the dental lab, and provides data such as integration of the face, lips, gingiva and teeth, as well as information regarding the shape, shade (guides), contour and function. All of which allows for the most beautifully executed of restorative jobs with less possibility of repetition. In addition, the photographic record facilitates the “before/after” comparison and the making of scientific panels, articles and classes, as well as documentation of procedures, materials and prosthetic parts as well as the close observation of natural teeth.12, 20, 22, 24, 27 93

DIGITAL PHOTOGRAPHY Although this technology have had its origins in the 1970s and the first digital camera was introduced into the market in the 1990s, the clinical use of this tool within the dental office only became a reality in the early twenty-first century.15 The possibility of the immediate display of a photograph, the elimination of film costs as well as developing and the systematization of the management of the images within the clinic are some of the advantages over the analogical system.15,17 We can conceptualize photography as the process of obtaining an image from the light captured by an objective lens (commonly known as a lens, but actually formed by a set of lenses). In digital photography, the photons (“particles” of energy) of light promote an electronic response onto a digital sensor (CCD – charge-coupled device), located within the camera body. These electrical signals are then recorded in bits in a memory card and may be stored and manipulated with computers.8,29 (Fig. 2) Learning to shoot, in short, means understanding and mastering the art of capturing and processing light.14 Three features of the light input should be balanced within the objective in order to record “faithful” images: quantity, time and sensitivity.8,26 The relationship between these three elements, ie the period during which an amount of light will reach a sensor with a predetermined sensitivity, is called exposition.26 The amount of light is determined by the diaphragm, a series of metal blades located inside the objective and controlled by commands from the camera body. These blades form a central orifice of adjustable opening through which the light which will reach the sensor passes. The aperture diameter is expressed in numerical fractions, conventionally known as f number. Since the number f is a fraction, the lower the f-number, the greater the aperture: a f/2.8 aperture has a much greater diameter and enables a greater amount of light to capture than a f/22 aperture.8,21,29

Diaphragm

Shutter

Sensor

ISO Figure 2.

Figure 2. Scheme with the operation of a digital camera and parts thereof.

94

When using large openings (e.g., f / 1.8 or f / 2.8), images are produced with lower field depth, ie a small area of the photograph will be well “focused” or quite clear, and everything that is ahead or behind that zone will be “blurred”, fogged. Small field depths are widely used in outdoor portraits because the “blur” of the irrelevant part highlights the selected object, but highly undesirable for dental photography, since we need to obtain images punctually highlighted in a framework in which all of the elements are relevant.8,21 As we decrease the aperture (increasing the f-number), we obtain a greater depth of field. Intermediary aperture values (f/8 to f/13) are of interest for landscape photography, where the sharpness provided by the aperture is distributed allowing for the photographed objects to be visible; however, if seen at higher magnifications, they do not have sharpness. Extremely small apertures (f/22 to f/32) are desirable for clinical photography, so that we can highlight and clearly observe both the anterior and the posterior teeth, as well as other structures involved. (Fig. 3a-d) For the carrying out of the facial photographs, medium apertures (f/11 to f/13) produce a sufficient field depth.8,21 The time of exposure of the sensor to the light is determined by the shutter, a mechanical device located inside the camera body, facing the digital sensor. The shutter works as a window that remains opened for a fixed interval allowing for the sensor to be reached by the light passing through the objective lens. Time can be expressed in seconds (1”, 5”, 30”) or fractions of a second (1/x: for example, x equal to 100 is 1/100 or a hundredth of a second). The shorter the exposure time, the less ammount of light will hit the sensor. In practice this means that, if all other variables are kept constant, the shorter the exposure time, the darker the image.8,21,29

Figure 3a.

Figure 3b.

Figure 3c.

Figure 3d.

Figure 3. Photographs with ideal settings of depth of field (high f-stop) allow for static and careful analysis of all components involved in the picture (f/22, 1/125, ISO 100). Importantly, the higher the f-stop,the higher the sharpness of the picture components that are distant from the central point of focus, that is, the depth of field increases. However, for this more flash power is required (a-b). Photos with inadequate defaults for depth of field (low f-stop) make it impossible to analyze all components involved in the picture around the central point of focus, due to the apparent loss of sharpness as it moves away from the main focus (f/8, 1/125, ISO 100). (c-d)

95

Because aperture openings required for clinical photography are very small, it is necessary that the light be captured for an extended period of time to obtain an image with balanced exposure, but during this period both the movement (shaking) of the photographer and the patient would be recorded on the image. For this and other reasons discussed below, it is necessary to use an additional light source, the flash, which has the function to add light to the photographic environment, so that it is possible to use small aperture openings over quite small intervals as well. The recommended time interval for dental photography is 1/125s.8,21 (Fig. 4a and 4b) The sensitivity of the sensor is determined by the ISO, expressed in numerical values, usually from 100 to 3200. The smaller the value, the less sensitive the sensor, and the less light it records, but on the other hand, sharper images are produced. As higher ISO values are used, it is possible to observe something called noise, like millions of tiny colored dots had stipled the entire image. (Fig. 5a and 5b) Higher ISO values are used under low light; for example, in dark environments or at night, without the use of a flash. In Dentistry, the ISO number used must be as low as possible (100 to 200), in order to produce the lowest noise level. Because the aperture used will be very small, this is only possible to the use of flash.8,21,29

Figure 4a.

Figure 4b.

Figure 5a.

Figure 5b.

Figure 4. Photographs of the same scenario with different shutter speeds and, consequently, different amount of light. The image shows the result of shot photographic setting with 1/8 second speed. Thus, it is possible to observe with certain clarity the objects in the picture without major distortions because the of light speed entering the capture sensor is high and produces a sharper image with respect to the components of the whole image ensemble (a). The image presents the results of a photo taken with a 1 second shutter speed. It is therefore not possible to clearly observe the objects in the image captured by the sensor due to the slow speed of aperture and closure of the shutter, which generates a distorted image of the components throughout the image with the visual sensation their movement. (b) Figure 5. Photographs of the same scenario with different ISO. The image was captured with a high ISO value (12,800), which promoted excessive image noise or blur (layman term) of the object. This situation is explained due to the adjustment of the ISO electronic sensor for high light sensitivityand indicated to capture photos in low light without the flash support. Considering that the images captured for Dentistry are obtained with flash, low ISO values are recommended, to not create noise (sharpness of detail). (a) The image was captured with a low ISO value (100), which allowed minimal image noise (high sharpness of detail). So, by analogy, it is concluded that dental photographs must be taken with the lowest ISO values, because is always used flash, and it is not necessary to sensitize the electronic sensor (ISO) to capture light emitted by the objects of interest. Thus, important details are kept. (b)

96

Another important feature of photography is the white balance (WB), defined simplistically as the color reading performed by the camera. This reading may be automatic or manual. When the white balance is automatic, with the variation of ambient light, there may be a variation with respect to how the camera interprets and records the colors. For obtaining images with the same color pattern, and for this pattern to be as close to natural as possible, it is suggested to use the white balance always in the “flash” or “daylight” mode or set at 5,600 K.21,29 WB adjustment differences occur due to differences in factory settings of the equipment as well as the building of light-capturing sensors. If the WB is not configured correctly, images may become “warmer” or yellowish. Ideally, the optimal adjustment is in the Kelvin mode (5,600 ºK), which is the most faithful to the color, however in cameras that do not have this WB module this difference may be compensated for by working on the adjustment of its chromatic map. This, in turn, compensates for the color reading by increasing or decreasing its temperature, from blue to yellow, or from red to green. (Fig. 6a-h)

Figure 6a.

Figure 6b.

Figure 6c.

Figure 6d.

Figure 6e.

Figure 6f.

Figure 6g.

Figure 6h.

Figure 6. WB K5600: ideal for dental photograph protocols of the mouth and face, this color temperature (or White Balance) equivalent to sunny daylight of midday, the most faithful to observe the color of teeth and other adjacent tissues. This is because invariably we use flash for dental photographs, which is equivalent to daylight. The other adjustments of White Balance will always produce distortion of the captured image due to the generation of average color temperatures, because we use dental flash in combination with the proposed adjustment. (a) WB Shade: lower color temperature control, tending yellowing the photos, when used with dental flash. (b) WB Cloudy: higher temperature setting, close to 9,600 tending to bluish the picture, because this considers as “cloudy” (gray environment, dim lighting) and corrects the ambient color in the final result of the photo. However, when using flash, the settings conflict and form a gently yellowish image.(c) WB Flash: specific regulation for the use of flashes. However, there are color variations depending on the manufacturer. For Nikon® equipment, Dental photographs can be made in WB mode; however, in Canon® equipment in the same setting the photos tend to become yellowish. (d) WB Daylight: nearest setting of the ideal temperature of 5,600 K, when the equipment does not have WB adjustment in Kelvin, ideal option is setting “Daylight” at 5200 K. For Canon® equipment, lacking the setting in Kelvin, this setting is ideal. In this image, the homogeneity is observed with the caption DEN 1920 image, because they were shot by Nikon® equipment. (e) WB Fluorescent: When in this mode, coupled with a flash, color temperature conflict results in a bluish picture. (f) WB Incandescent: When in this mode, coupled with a flash, the color conflict between yellow (incandescent) and “white” flash results in a greenish image. (g) WB Automatic: when used with flash, the final temperature is close to the “Flash” mode. (h)

97

EQUIPMENT CHOICE FOR CLINICAL DENTAL PHOTOGRAPHY The ideal camera body for Dentistry is called the Digital Single Lens Reflex (DSLR), which allows an interchangeable objective. In compact cameras, lens and body are joined, forming a single structure. (Fig. 7a) Despite their ease of use and the affordable price, their use is limited to professional use, since this type of camera does not allow for the use of other objectives or external flashes, besides presenting limitations related to the specific settings for Dentistry. There are many different DSLR camera bodies available on the market, and there are frequently releases.8,21,29 The difference between the cheapest and the most expensive professional equipment are primarily the technological resources applied to image-capture sensors, as well as functions that make life easier for the operator, such as picture -by-picture cropping, color adjustments, contrast, saturation, brightness, texture and sharpness, features that were once only made possible through the use of a personal computer, after downloading the images. Moreover, the body of equipment is generally more resistant. DSLR equipment have at least 18 megapixels, this resolution is more than adequate for dental photographs. (Fig. 7b) The most important aspect applicable to the choice of equipment for clinical dental photographs are the choices of the objective and the flash. Image quality is defined by the quality of the objective and the quality of the image capturing sensor. The more expensive the body of the machine, the better are their sensors. In this case, it is desirable to obtain reliable images without distortion, of the photographed subjects: teeth, gingiva, lips and face. This is only possible with lenses that have a focal length above 90 mm. Focal length is the distance between the point of light convergence in the first lens on the objective entry, to the image capturing sensor. Lenses with a normal to wide focal length (10 mm to 55 mm respectively) usually cause distortion of the photographed subject. It also should be considered that the teeth are small objects, which will be photographed at short distance, what is merely allowed when using macro type lenses. Macro lenses enable an upclose approach to objects, similarly to a magnifying glass, without preventing long distance shooting. The 100 mm and 105 mm macro lenses, sold by Canon® (Japan) and by Nikon® (Japan) respectively, are the most suitable for both intraoral photographs (teeth) and extraoral (smile and face).8,13,19,20,23,30 (Fig. 8a and 8b) The most suitable flash model is a special flash for macro photography. It is tailored at the tip of the lens, located right next to the photographed subject, and because it has at least two light sources (ringflash or punctual) there is little or no shade formation4,8,17 as well as creating a minimum amount of texture and volume. The twin flash or bipunctual is the most difficult to handle, although it can provide greater capture of details, texture and volume, especially if diffusers are used. Rapid and growing technological advancement has made this equipment increasingly affordable.21,29 (Fig. 9a-d) Among the various shooting modes, clinical dental photography is one of the most practical and direct, requiring nearly standardized specific equipment and techniques for performing shots.7,10 Thinking about it, the EyeSpecial® II photographic equipment (Shofu, Japan), released in 2014, combines a great majority of DSLR characteristics with the advantages of a compact machine, which facilitates the capture of professional quality images similar to those obtained with Reflex equipment. (Fig. 7c)With intuitive concept 98

and pre-programmed shooting modes as well as being defined by an image type of interest, this equipment demystifies clinical photography, facilitates capturing and dental records, and maintains the high standard of image quality required for the development of appropriate rehabilitation planning, ie is an excellent alternative for professionals who do not intend at scientific and didactical production of materials generated by professional cameras. The structuring of a clinical protocol of photographs to be obtained enables allow for systematic organization of the dentist, which facilitates as much the photographic techniques as well as the storage and use of the images.

Figure 7a.

Figure 7b.

Figure 7c.

Figure 8a.

Figure 8b.

Figure 9a.

Figure 9b.

Figure 9c.

Figure 9d.

Figure 7. Different cameras found on the market: compact machine, not indicated for use in Dentistry (a); DSLR type professional machine, most suitable model for use in practice (b); and EyeSpecial® II equipment (Shofu, Japan), for specific use in clinical photography (c). Figure 8. 100mm (Canon®) e 105mm (Nikon®) macro lenses, which can be adapted to DSLR machines for clinical photograph. Figure 9. Flashes for macro photography available for dental photography: ringflash (a-b) and twin (c-d).

99

PHOTOGRAPHIC PROTOCOL FOR DENTISTRY (Fig. 10)

Figure 10.

Figure 10. Set (minimum) of pictures that compose the photographic protocol recommended by the authors of this book.

100

First, it is important to ensure the quality of photographs taken not only by photographic techniques, but taking care of what should or should not be captured in the images. Preferably, the patient should not be with adornments or ornaments that take the viewer’s attention, such as necklaces, earrings, hairstyles or strong colored lipsticks. In the case of long hair, it must be bound with elastic or thrown behind the shoulders. Every tooth must display little or no saliva and should be free of other effects that produce distraction. Procedures such as impressioning, occlusal adjustment and others which may leave residues or marks on the teeth or skin of patients should be performed after shooting, because the captured image probably will be compromised by the presence of impression material residues, labial and facial marks caused by modeling, dehydration of the teeth, etc. In the case of inflamed and/or infected gingival tissues, as well as the presence of extrinsic stains, plaque and calculus, images should be obtained after the patient undergoes the basic therapies of oral hygiene and oral adequation through the control of inflammatory processes, except in cases where the capture of the images of these clinical conditions is relevant.17,18,21,26 The choice of the photographs to be made in the photographic protocol is the dentist’s responsibility. The basic recommended protocol comprises facial shots with labial sealing, facial with lips at rest, facial of the smile, dento-labial with lips at rest, frontal and lateral of the smile, intraoral in occlusion (frontal and lateral), upper and lower of the occlusal with mirror, anterior teeth with black background and photos with a shade guide. It is interesting to adopt standardized shots and adjustments of equipment, to facilitate and enable future comparisons. 17,18,19,21 (Table 1)

Table 1. Equipment settings and accessories needed for each of the involved photographs in the photographic protocol.

FACIAL

PHOTOGRAPHS

ACCESSORIES

MACHINE SETTINGS

Frontal: lip seal, lips at rest, smile

black contrast

Aperture: f/11 to f/13 Speed: 1/125

. .

Profile: lip seal, lips at rest, smile . .

. .

DENTO-LABIAL

Frontal: lips at rest, smile

none

Aperture: f/22 to f/32

. .

Profile: smile

. .

Speed: 1/125

INTRAORAL . .

occlusion frontal, occlusion lateral, maxillary teeth, black contrast

“C” and/or “V” shaped lip retractors, with black contrast. .

SHADE GUIDE . .

smile, with retractor and black contrast

“C” shaped lip retractors, black contrast, shade guide .

OCCLUSAL

occlusal maxilla, occlusal mandible

“C” shaped lip retractors, occlusal mirror

ISO: 100 to 200 White Balance WB: Flash (Nikon®), daylight(Canon®) or Kelvin (K) 5,600 Flash output: 1/2 or 1/4 in manual mode

ISO: 100 to 200 White Balance WB: Flash (Nikon®), daylight(Canon®) or Kelvin (K) 5,600 Flash output: 1/2 or 1/4 in manual mode . . Aperture: f/14 a f/16 Speed: 1/125 ISO: 100 to 200 White Balance WB: Flash (Nikon®), daylight(Canon®) or Kelvin (K) 5,600 Flash output: 1/2 or 1/4 in manual mode

101

The manufacture of a simple photographic protocol for Dentistry includes accessories like: 1. professional digital camera equipment and accessories (eg a Nikon D600® camera, AF-S Micro NIKKOR® 105mm f/2.8 lenses and Nikon SB-R200® twin flashes (Fig. 11a); 2. mouth openers (eg “C” and “V”shaped adult lip and cheek retractors) (Fig. 11b-d); 3. set of contrasts for photography (eg Flexipalette®, Smile Line, Switzerland) (Fig. 11e-g); 4. mirror set (e.g., crystal or metallic mirrors) (Fig. 11h); and 5. Basic kit for performing the prophylaxis and removal of extrinsic stains.13; 21;28

Figure 11a.

Figure 11b.

Figure 11c.

Figure 11d.

Figure 11e.

Figure 11f.

Figure 11g.

Figure 11h.

Figure 11. Accessories used in the preparation of the photographic protocol: (a) Professional digital camera and accessory equipment; (b) “C” and “V” shaped adult mouth props; (c) set of contrasts for photo (Flexipalette®, Smile Line, Switzerland); and (d) set of metallic mirrors.

102

EXTRAORAL PHOTOGRAPHS

The first pictures to be made in the photographic protocol are extraoral photographs, since the retractors and mirrors required for intraoral photographs may leave marks on the patient’s skin and compromise the quality of the extraoral images to be obtained. there are two main types of extraoral photos: facial, close-up of the lower face, or dentolabial. PHOTOS OF THE FACE For facial photos, values should be set  from 11 to 13, the exposure time should be set at 125 (1/125 second), and ISO (sensitivity of the light sensor), between 100 and 200, for less noise. The white balance should be adjusted to the flash or day-light mode or the 5,600 ºK option. The flash light must be set in “manual” mode and power ½, but it may also be modified using bouncers and diffusers.19,21,28,29 Framing should include head, neck and part of the patient’s chest, not extending too much to the cervical region.17 FRONTAL FACIAL Frontal images must be obtained with the patientin the prone position , with the camera located perpendicularly to the patient nose level, to facilitate and standardize obtaining a constant vertical angle during the “before” and “after” photos. A predictable manner to avoid distortions is to position both the patient and photographer standing or sitting, ideally on the same horizontal plane. The patient’s head must be positioned so that their nose is placed at the center, the interpupillary line is parallel to the horizontal plane to prevent vertical tilting, and the Frankfurt plane is as parallel as possible to the horizontal plane, to avoid horizontal tiltings and consequent analysis of distortions. The picture’s background should be neutral and uniformly colored. Within these images, along with the facial midline (vertical), some horizontal lines are drawn in order for a patient’s facial analysis from the definition of the thirds of the face to be made by observing the following features: • hair line (horizontal); • eyebrow line (horizontal); • interalar line (horizontal); and • mentus base line (horizontal). Frontal images of the patient’s face at different positions must be obtained for a more comprehensive analysis of the face - with labial sealing, lips at rest and smile. a) Face with labial sealing (Fig. 10a). In this initial facial image, the patient should be position with sealed lips. b) Face with lips at rest (Fig. 10b and 12). The photo should display the patient’s face with lips slightly parted in a resting position. c) Smiling face (Fig. 10c). The image of a the patient exhibiting a natural smile without the mouth open as in “laughter” and without the lips being stretched or distorted. This shot must be taken quickly at the very moment the patient cracks a smile, because a very few people are able to maintain the lips in position for more than a few seconds. Nevertheless, a number of images of the smile should be optimally taken, because it is possible to capture it at diffe103

rent degrees, each photo contains valuable information for the aesthetic planning, making it possible to select the captured images. In this photo, the use of a digital facial bow is recommended as a standard for analysis and aesthetic reference, which is composed by the following lines (Fig. 13): • facial midline; • lines of the nose wing; and • line of the incisal edge. Some horizontal lines which were already been discussed in Chapter 2 of this book can also be traced in the same photo. The literature is unanimous on the importance of the parallelism between these horizontal lines of the face for harmony and aesthetics, and they must also be perpendicular to the midline.3,5,11 These lines are: • interpupillary line: passing through the center of the pupils in both eyes; • eyebrow line: passing over the eyebrows; • line of the labial commissures: touches the corners of the lip on both sides; • occlusal plane: tangent to the incisal edges; • line of the incisal edge: contours the incisal of the six anterior teeth; and • mentus line: tangent to the base of mentus. (Fig. 14)

Figure 12.

Figure 13.

Figure 14.

Figure 12. Parallelism between the horizontal lines of the face, which must also be perpendicular to the centerline, and aesthetic harmony are observed. Figure 13. It is observed that the nose wing lines are tangent to middle third of the labial surface of the premolar and reveal that the canines need labial volume for establishing an ideal condition, which is the tangency of the nose wing line in the distal portion of the maxillary canines, revealing an ideal relationship of width of the six anterior superior teeth in the smile. Detail for parallelism found between the line of the incisal edge and the curvature of the lower lip. Figure 14. Digital bow established with the tracings of the interpupillary line, eyebrow line, line of the lip commissures and the occlusal plane: tangent to the incisal edges; line of the incisal edge: incisal contour of the six anterior teeth and chin line.

104

PROFILE OF THE FACE (Fig. 10d-f) Identical references taken from the frontal aspect are then taken of the patient’s profile, from both the right and the left side: labial sealing, lips at rest and the smile. It is important to note that the patient must be totally to the side, which provides a superio contour of the face. There should not be any vertical or horizontal tilting of  the patient’s head and the previously mentioned reference position must be observed. In the profile picture of the patient, three points are defined: glabella, subnasal and pogonion. The angle formed by the union of these three points will define the patient’s profile as normal, convex and/or concave.5,11 (Fig. 15a) Other profile references are used to evaluate the harmony of the face and its consequences, such as: • Line E: connects the tip of the nose to the mentus tip; (Fig. 15b) • nasolabial angle; and (Fig. 15c) • true vertical line: a perfectly vertical line drawn approaching the patient’s face from profile until touching the nasolabial angle and, ideally, it is observed that the nose should be 8 mm to 10 mm beyond, the upper lip, 2 mm to 5 mm, the lower lip from 0 to 3 mm, and the pogonion must be up to 4 mm. (Fig. 15d) Both line E as well as the nasiolabial angle may be significantly changed after prosthetic treatment.

Figure 15a.

Figure 15b.

Figure 15c.

Figure 15d.

Figure 15. Convex profile. Class II, or convex profile patient with low dominance of the central incisors by the incisal (a). Analyzing line E, the upper and lower lips are below the line, which imparts an aspect of normal profile (b). Nasolabial angle greater than 95º and in disagreement with the ideal reference for men (c). Analyzing the true vertical line, it is observed that the upper lip does not exceed the referred line ideally 2.0 mm at the very least. This discrepancy is coincident with the discrepancy of the nasolabial angle, suggesting lingual inclination or absence of tooth volume of the maxillary teeth. (d)

105

DENTOLABIAL For this group of photos higher values should be set, between 22 and 32, and the exposure time, as well as the ISO number for the the same facial shots are used (1/125 second and 100/200, respectively). The white balance will also be adjusted to flash, daylight or the 5,600 ºK position.The flash output this moment may be from ½ to ¼ within the “manual” mode.19,21,28,29 The framing should include the base portion of the nose, cheeks and chin, and the entire patient’s mouth. The center of this image varies according to the different patient positions. a) Lips at Rest (Fig. 10g) The photo at rest is aimed to evaluate the degree of dental exposure with the lips at rest, especially the maxillary central incisors, which should show the lips slightly parted, and the upper lip philtrum should be at the center of the picture. (Fig. 16) b) Full Frontal Smile (Fig. 10h) The photo should show full smile, the lips with a naturally broad smile, without the mouth being open as if “laughing” and without the lips being stretched or twisted. As with the facial shot, this should be done briefly and repeatedly, seeking to capture the most natural and spontaneous smile of the patient. Still, the upper lip philtrum must be positioned in the center of the photograph, and the incisal plane of the maxillary teeth (aligned parallel to the interpupillary line) should be horizontally positioned in the center of the image. If there is any discrepancy of the midline, inclination of the smile or of the incisal plane, evident within the full facial view, then this identical asymmetry should be reproduced. (Fig. 17) In this photo, the analysis of the following aesthetic features may be carried out: • the smile line; • buccal corridor; • the incisal curvature; and • curve of the lower lip. c) Full Lateral Smile (Fig. 10i) With the same characteristics mentioned for obtaining the image of the full frontal smile, the photograph of the full lateral smile has the same vertical angle as the frontal photos, though obtained laterally, with the maxillary lateral incisor centrally positioned in the photograph, being possible to view the central incisors and the opposite lateral. In cases where the width of the smile is important, the opposing canines are also visible. This photograph should be taken from both sides of the patient’s mouth. In this image, it is possible to laterally evaluate the same conditions described for the frontal shot of tooth/lips.

106

Figure 16.

Figure 17.

Figure 16. The photo at rest shows the ideal tooth exposure for men on average 1.9 mm.

INTRAORAL PHOTOGRAPHS

Figure 17. Detail for the parallelism of the line of the incisal edge and the line of the lower lip curvature, showing a condition of normality.

The intraoral photographs are taken with the same settings used for those of the lower face: f/22 to f/32 aperture, 1/125 second speed, ISO 100 or 200, white balance set to flash, day-light or 5,600 ºK, and the flash output set from ½ to ¼ in the “manual” mode.20,21,28,29 a) Intraoral in Frontal Occlusion (Fig. 10j) This image should be obtained with lip retractors for the full visibility of the gingiva of all the teeth. It can be taken in prone or frontal position of the patient, standing or sitting, similar to the previous shots or behind them. For the last option, the patient should be lying down enabling the photo axis to be perpendicular to the subject, with the median sagittal plane parallel to the vertical, and the occlusal plane parallel to the horizontal borders of photograph. b) Lateral Photo of the Maxillary and Mandibular Teeth (Fig. 10k) The maxillary and mandibular teeth should be occluded. The maximum amount of gingiva should be visible, as seen in the photo of the lips with the retractor. The maxillary lateral incisor should be the center of the image as well as the opposite central incisor should be visible. In cases where arch width is of significant importance, the opposite lateral incisor and canine appear in the picture obtained. Repeat the protocol on the opposite side. c) Maxillary Teeth with Contrast for Photography (Fig. 10l) Similar to the intraoral technique with frontal occlusion, this technique should be performed with lip retractors, providing gingival visibility for all of the maxillary teeth, and may be carried out in the frontal position to the patient or behind them. Differently from the previous one, in this shot contrast for photograph, a black background, should be placed between both arches of the patient, as far as possible from the anterior superior teeth, to prevent viewing anything other than the teeth and gingiva of the maxillary arch. 107

This image is critical to evaluate: • principles of gingival aesthetics: • gingival contour; and • gingival zenith (Fig. 18a); and. • principles dental aesthetics: • axial inclination (Fig. 18b); • dental position and arrangement (Fig. 18c); and • width/length ratio (Fig. 18d). During the appointment, it is necessary to obtain actual measurements of the face and teeth with the aid of a mechanical or digital caliper, ie, the interpupillary distance, mouth width, width of the smile, width and length of the central incisors and width of the six anterior teeth. Based on these measurements and the pre-established aesthetic principles widely discussed in Chapter 2, it is possible to determine the new optimal dimensions, which allow for making suitable dental sizes for this patient, according to an individual analysis, and not from common patterns of the population (Fig. 19). Thus, the cosmetic rehabilitation planning becomes individualized, being based on the particular dimension of the patient. A relevant factor in the planning of an aesthetic rehabilitation is to consider the difference between the evaluation of teeth with their actual anatomical width and their optical width.9 When measured directly within the mouth and when measuring with the use of digital photography planning, teeth have different dimensions, especially with respect to the width, since the frontal view of the patient does not coincide with the dental frontal view. (Fig. 20) This oc-

Figure 18a.

Figure 18b.

Figure 18c.

Figure 18d.

Figure 18. Gingival contour with small length discrepancy of the canines compared to the centrals. Gingival zenith of canine positioned further down; (a) ideal axial inclination (b) and laterals are within the horizontal lines drawn between the gingival zeniths of the central incisors and canines (c); width/length ratio (18d).

108

Operative Dentistry – Ideal Dimensions Central Incisor

Lateral Incisor

Canines

63

Lateral Width

Canine Width

Width of the Central Incisor

Width of the Central Incisor

C.I. Width

C.I. Width

÷ 6,6 9,54

÷ 7,2 8,75

x1,33

x1,25

x1,33

x1,25

12,68

11,92 10,93

11,63

-25% (x0,75)

6,97

Length x Width - Ratio 100%

-15% (x0,85)

0,5 or = CI

7,9

With Diastemata

Check with D.I if it is greater the maximum acceptable refer to Orthodontics

Lateral Length

Canine Length

Equal to the Length of the Central Incisor

Equal to the Length of the Central Incisor

x x+y+z=

-0,5 or equal -0,5

Width 9,3

Length 11,62

85%

-0,5 to 1,5mm

Minimum and maximum acceptable length of the central incisor

Selected Design of the C.I.

75%

-0,5 à 1,5mm

y

z

18,6 ÷ 2 =

9,3

Measurements For Wax-up

-0,5 à 1,0mm

-1,0

-0,5

INCISAL

CERVICAL

Final Value = 11,12

11,62 9,3

11,12

10,1 6,97

7,9

Final Value = 10,1

Figure 19.

Figure 20.

Figure 19. Schematic instructional drawing of the ideal dimensions (width/length) calculations . Figure 20. Ideal widths measured in photography in the digital planning. The teeth have different dimensions, since the frontal view of patient does not match the tooth frontal view.

109

Figura 21a.

Viewer

Maximum rotation of the central incisors is 25º

Figura 21b.

Optical width

Anatomical width Figura 22.

Figure 21. Another case as an example, the maximum acceptable rotation of a tooth in an acceptable digital planning is 25º (a) from the optics of the observer, confirmed by the transferor. When the tooth rotation is greater than 25º, the digital tracing loses its validity, as it starts to suggest an unreal contour, since the screen is “2D or two-dimensional,” and the smile, “3D or three-dimensional”. Rotation beyond 25 ° is already applied starting from the lateral incisors, invalidating the tracing in relation to the width of the future designed teeth (b). In this photo one can see, through digital rules calibrated previously, the width of the lateral incisor is different when we have the digital (observer/computer) and anatomical view of the same element. The transferor shows the 41º of natural rotation of the upper arch, preventing any assumed digital trace for the definition of the actual width. Figure 22. Actual anatomic width compared to the optical width.

110

curs as a consequence of inclinations of the teeth, the shape of the dental arch, rotations of teeth and any possible overlapping of a tooth with another.9 Therefore, when calculating the optimal tooth size from the interpupillary distance, and considering all the facial aesthetic references,the values obtained for the width of the teeth can not be applied directly on the frontal photo of the smile or even with retractor to make it appear wider than ideal, generating an overlap and consequently a confusing planning effect. From the patient’s frontal view, the only teeth that appear in an anatomical frontal position are the central incisors; as we move towards the posteriors, the other teeth will suffer spins on the arch, which generate a downward effect from their optical width.Therefore, when mounting the digital simulation of the ideal dimensions of the patient, it is necessary to consider the rotation of teeth within the arch and the effect of reducing their widths posteriorly. (Fig. 21a-b) For this reason, digital planning should be used judiciously, and it should be explained to the patient so as not to generate a misguided virtual presentation of the actual outcome. (Fig. 22) d) Photo with Shade Guide (Fig. 10m) For proper shade registration of the patient’s teeth during treatment and especially for communication with the laboratory, three photos are recommended to be taken with the use of a shade guide placed next to the teeth: one of the smile, one in occlusion with a retractor and one with retractor and contrast when taking the photograph. The shade guide should be placed incisally with relation to the teeth in the same horizontal plane as the central incisors, or as close to this plane as possible, without tilting, so as to eliminate any possible variations in the amount of light received, which would cause variations in shade registration. e) Occlusal Maxillary (Fig. 10n) Occlusal photographs are always obtained through image reflection, with the highest quality mirrors. For this shot what is interesting is to increase the aperture (to decrease the f-stop values from 14 to 16), since the ability of the flash to illuminate the scene being shot is smaller, because it is a mirror image. Also, since all of the teeth are on the same plane, the aperture is more than sufficient for the whole occlusal plane to appear completely. Keeping the mirror clear with the aid of a mild jet of air with its posterior portion as far as possible from the molars, the teeth of interest should be included in the frame, with the entire arch placed in the center of the photograph, and with the patient’s mouth opened as wide as possible. The angle of the mirror should be arranged so that the reflected image offer condition of a shot as perpendicular as possible to the occlusal surfaces of the teeth, enhancing the preview of size and shape of the embrasures. Partial inclination of the patient, with the head tilted back, will help when carrying out the maxillary occlusal photo. In addition to the mirror, lip retractors must also be used, to remove the lips from the perspective of the anterior teeth, so that about a third of the buccal surface of these teeth from an occlusal view may be seen. For the picture to have a good depth of field, it is suggested to focus on the occlusal of the premolars.

111

f) Mandibular Occlusal (Fig. 10o) Similarly to the maxillary occlusal technique, lip retractors and mirrors are used, in addition to the identical aperture settings. Most importantly when taking this shot is to exhibit the labial embrasures of the anterior teeth as if they were being observed from the incisal edge, making sure that the angulation of the mirror does not reflect a picture with a greater highlight of the buccal or lingual surfaces, reducing the possibility of observing the shape and size of the embrasures. The photographic protocol is not static; It can and should be adapted according to the needs of the professional and ceramists, with the exclusion or the addition of photos, always with the objective of optimizing the inter-communication and favor the accuracy of the results. Most importantly is to standardize the collection and the storage of images for later comparisons and observations, to facilitate communication with the patient and the laboratory, and to create a collection of case histories which can be used in classes, conferences and research. In short, today’s high-level Dentistry requires obtaining high quality images, which requires investment and appropriate training. The aesthetic rehabilitation planning is a tool that serves as yet another way to optimize communication among clinician, the patient and the laboratory, in order to minimize surprises in the outcome. It should serve as the basis for a good waxing and carrying out the mock-up. Finally, this will result in tridimensional

Since all these factors have been studied, individualized to the patient and determined through of the aesthetic rehabilitation planning, the professional will be in the way of a thorough and accurate diagnosis of the case and be able to create a complete and individualized treatment planning. After the preliminary treatment planning is built on the photographic protocol, one can carry out a wax-up on the stone model, so that the information is evaluated three-dimensionally. It is necessary to identify the objectives to be achieved and what changes should be made in smile looking to maximize aesthetics and function.8 The tooth wax-up has several functions, including to serve as a test of the planning for the dentist, for the technician and the patient when being transferred to mouth as a mock-up or restorative trial. This allows for all of the features to be achieved in the patient’s mouth to be analyzed previously to perform any intervention. When one aims to promote any type of tooth position correction when there will be interference of the original volume of the patient’s teeth, the wax-up may be left with excessive volume and, at the time of mock-up, cause surprise to the patient,.16 In this case it is necessary the patient to be informed that excessive volume will be corrected before the final result, preparations or by means of some kind of minimal adjustment which can be made in the teeth prior to impression for wax-up, thereby obtaining a more accurate model for the desired final outcome and a more pleasant mock-up. Another less realistic possibility is the exclusive presentation of digital planning without producing any preparation prior to the acceptance patient’s for making the wax-up and completion of the mock-up. 112

WAX-UP TOOTH (Fig. 23)

visualization of the proposed treatment planning.

The wax-up, still, may be applied in the production of a reference guide for the tooth preparation which is not to be based on the existing tooth contour, but rather on the expected final volume, allowing for one to obtain the final porcelain restoration with an uniform thickness and improved strength of the tooth-restoration set.16 The wax-up may still be used in the production of a silicone guide, which may be utilized when carrying out the provisional restorations, to facilitate obtaining an aesthetically pleasing result as well as maling it possible for the patient to adapt to the new dental dimensions and shapes.25 For the accomplishment of the wax-up detailed knowledge of dental anatomy is required, along with intuition, sensitivity and good perception of the patient’s personality and his expectations.16 Using the information of the ideal aesthetic principles, dental and facial measurements, and photos, the aesthetic rehabilitation planning makes it possible to determine the ideal lengths and widths of the teeth, in addition to the ideal shape. All of which may be reproduced in the wax-up and distributed in the cervicoincisal and mesiodistal directions in the rehabilitation outline. Cases of reconstructions and extensive aesthetic restorations should comply with all of the previously described steps, in order to achieve the desired result. These cases are carried out three times, using three different materials, wax, acrylic resin and porcelain, each of which confirms the steps above, to achieve the best final result. By following them the final rehabilitation work is transformed into a certainty and places the entire planning in the hands of the dentist, without surprises, guesswork or assumptions, based on true measurements and real possibilities.

Figure 23.

Figure 23. Tooth wax-up accomplished with white wax (Inowax®, Formaden, Brazil) from the ideal dimensions established by the facial reference. Notice that the wax-up was carried out over the gingiva of the stone model of teeth #13, #14, #25, #24 and #25. These teeth, according to Figure 18, exhibited a gingival zenith slightly below the ideal.

113

which corresponds to a test of the initial planning, carried out directly in the patient’s mouth. Before carrying out any preparation within the patient’s mouth, it would be ideal if the patient could evaluate and approve the mock-up, and know exactly what to expect from the treatment so that the dentist, may please him. The mock-up should be shown to the patient, and the professional should help them go over and verify that the aesthetic rehabilitation planning, the digital planning and wax-up performed are compatible with their

MOCK-UP

With the wax-up in hand the mock-up or restoration try-in should be performed,

personality, face, smile, masticatory function and subjective expectations,16 as well as presenting any possible limitations of the results which are dependent upon the patient’s initial conditions. This procedure may be performed on study models through the wax-up and subsequently transferred to the patient’s mouth using bis-acrylic resin or PMMA resin; or even as a direct intraoral restorative trial performed with composite resins.6 Mock-up types are presented below and in Table 2: • Direct mock-up with composite resin: characterized by the transfer of the aesthetic rehabilitation planning directly into the patient’s mouth with light-cured composite resin. Typically carried out with enamel resins due to its excellent polishability and immediate mimetism using ceramics, applied in a single layer over each tooth without any acid etching, distributing the resin in a cervicoincisal and mesial-distal direction, and shaping the tooth as established by the planning, always to be based on the prescribed aesthetic principles. Despite the imperative necessity to manipulate the composite resin with dexterity and of offering an idealized morphology which includes application, finishing and polishing, this technique saves time between appointments.(Fig. 24a-K)

Figure 24a.

Figure 24b.

Figure 24. Direct mock-up with composite resin. Insertion of the composite resin (Beautifil® II, Shofu, Japan), shade BW, on the tooth structure, without hybridization using the appropriate spatula (a); accommodation of composite resins with specific brush (Shofu®, Japan), which defines the tooth morphology (b); use of coarse-grained diamond discs (Sof Lex Pop-On®, 3M ESPE, USA) for correction of anatomical details (c-e). This step is carried out post-polymerization and evaluation of the patient from the frontal aspect. The most practical way to carry out this evaluation is to have the patient positioned seated and facing the observer. So the dentist, with a direct frontal view, may analyze and evaluate any possible previously imperceptible details, when the patient was lying; preparation of surface texture with a ultrafine diamond point (Komet®, Ale) (f); fine polishing with abrasive rubbers for composite resin (Composite Technique Kit®, Shofu®, Japan) (g-h); final gloss established with goat wheels (i); and final result of direct mock-up (j-l).

114

Figure 24c.

Figure 24d.

Figure 24e.

Figure 24f.

Figure 24g.

Figure 24h.

Figure 24i.

Figure 24j.

Figure 24k.

115

Figure 25a.

Figure 25b.

Figure 25c.

Figure 25d.

Figure 25e.

Figure 25f.

Figure 25g.

Figure 25h.

Figure 25. Indirect mock-up with bis-acrylic resin. Fabrication of a high viscosity silicone guide, preferably laboratorial (Zetalabor®, Zhermack, Italy) (a); high viscosity silicone guide relined with low viscosity material (Oranwash®, Zhermack, Italy) (b); cross-section of the guide with a #12 scalpel blade about 2 mm above the gingival margin to facilitate the removal of excess bis-acrylic resin (c); dispensation of bis-acrylic resin into the guide, which is brought to the patient’s mouth (d); removing excesses after 5 minutes with explorer (e); result after immediate removal of the guide (f); after cleaning with gauze soaked in alcohol (g); and excess removal with #12 scalpel blade (h).

116

• Indirect mock-up with bis-acrylic resin: where the aesthetic rehabilitation planning is transferred to the patient’s mouth with bis-acrylic resin. Despite its good finishing and polishing characteristics, bis-acrylic resins are monochromatic and may cause great estrangement to the patient with respect to the immediate result. Therefore, it is recommended to carry out a wax-up that offers not only the ideal dimensions, but a maximum of morphological and surface texture features. In this manner, the reflection of light is controlled, so that what will be valued is its highlighted idealized dental morphology. (Fig. 25a-h) • Indirect mock-up with acrylic resin: differs from the mock-up with bis-acrylic resin due to the rigidity of the acrylic resin mock-up, fabricated in the laboratory. Despite its excellent polychromatic property, it is possible to be applied and exhibit an excellent finishing and polishing, the high cost must be taken into consideration, except for cases of anticipated periodontal surgery, inwhich this technique is preferable (Chapter 2, page 53, Fig. 26a-d).

Table 2. Characteristics of each of the three types of mock-up explained in chapter.

COMPOSITE RESIN MOCK-UP

BIS-ACRYLIC RESIN MOCK-UP

ACRYLIC RESIN MOCK-UP

Mean clinical time (±1 h)

Mean clinical time (±1 h) .

Short clinical time (±15 min) .

Time between impression/ wax-up and execution of mock-up

Absent . .

Short .

Laboratorial stage

Absent

Only wax-up

Costs

Low

Low

Demarcation of the initial incision line

Regular .

Good

Finishing and polishing adjustments

Yes .

Yes .

Handling

Operator-dependent

Hard

Use during the surgical procedure

Regular .

Good

Polishing and texture

Excellent

Good

Clinical stage for the execution of the mock-up

.

.

Long . . Difficult and elaborate High

. .

Excellent . Yes .

.

Easy .

Excellent .

.

Excellent

Before the explanation and all of the characteristics are evaluated, the authors preferably recommend using the bis-acrylic resin indirect mock-up for clinical evaluation as well as for presentation of the aesthetic rehabilitation planning. Such a condition does not rule out the use of another type of mock-up, the indication and performance of which depend upon the preference and skill of the operator, speed, available working time, evaluation of labor costs etc. That being said, directly below some steps have been presented towards the establishment of a predictable protocol to carry out an efficient mock-up, which will lend important and valuable information to the planning of each case. 1. Fabricating the PVS guide Accomplishment of the mock-up is obtained through the necessary use of a silicone guide as faithful as possible to the wax-up, transfering to the patient’s mouth the maximum of morphological details and surface texture which has been preestablished, taking into account the monochromatism of the bis-acrylic resin used for this process, which minimizes the aesthetics of this assembly. For this, the following techniques have been suggested: A. Fabrication of a wax-up faithful to the designed aesthetic planning rehabilitation, reproducing morphological details and surface texture. (Fig. 23) B. Fabrication of a high-viscosity silicone guide, (preferably a laboratorial silicone, Zetalabor®, Zhermack, Italy), firmly applied over the waxed model, involving the entire buccal and lingual surfaces, with sufficient thickness to facilitate the correct positioning in the mouth. It is necessary to involve one to two teeth on both sides, beyond the planned rehabilitation, to facilitate the stabilization of the guide and avoid displacement which may lead to deformations in the final result of the mock-up. (Fig. 25a) 117

C. After polymerization, the high-viscosity silicone guide is removed from the model and relined with a low-viscosity silicone (Oranwash®, Zhermack, Italy), without creating a relief, which will allow for the best reproduction of the morphological details and surface texture of the produced wax-up as well as for the installation of a mock-up with less excess and a more refined anatomy. (Fig. 25b) 2. Trimming the guide with scalpel blade To facilitate the removal of excess bis-acrylic resin, the guide must be trimmed with a #12 scalpel blade, approximately 2 mm above the gingival margin, following the contour of the waxed teeth, so that there is a minimum amount of resin in the region as well as allowing for it to be easily displaced. It would be ideal if the palate was also cut in order to allow for the outflow of excess resin from the region as well as to avoid any overcontours of the mock-up.16 (Fig. 25c) 3. Dispense the bis-acrylic resin in the guide and lead to the patient’s mouth After discarding the small initial portion, which normally does not polymerize, into the self-mixing dispenser, it should be applied to the guide so that the first portions are placed with the mixing tip touching its bottom. This maneuver minimizes the formation of bubbles within the mock-up and helps promote uniform distribution of the resin into the guide. The loading of the guide is performed in an agile manner, due to the rapid polymerization reaction of this material, which then must be placed into the patient’s mouth and pressed and held firmly into position. For this, occlusal pressure should be exerted on the guide over the teeth which are not involved in the rehabilitation, in order to allow for the complete and correct seating of the assembly and the proper overflow of any excess material that should be immediately light cured, facilitating its removal before the 5 minutes of the final chemical polymerization of the assembly into the guide.16 The correct positioning of the guide also directly influences the thickness of the mock-up, possibly leading to an incorrect patient evaluation.16 (Fig. 25d) 4. Remove excess After 5 minutes, before the removal of the guide, the overflow excesses of the bis-acrylic resin, both on the buccal surface as well as on the palate, may be removed with a dental explorer so as to minimize any future adjustments to be carried out later with a scalpel blade. (Fig. 25e) 5. Remove the guide and cleanse the mock-up Five minutes after the polymerization of the bis-acrylic resin and removal of the overflowed excesses, the guide may be carefully removed from the patient’s mouth. With an alcohol-soaked gauze, to remove the unpolymerized superficial layer of the bis-acrylic resin which was inhibited by oxygen. (Fig. 25f-g) 6. Relining and removing cervical excesses Small repairs may be carried out if there exist any bubble formation or excess loose 118

resin portions. The literature reports the difficulty of performing bis-acrylic resin repairs,1,2 but since the mock-up should only be used for a short time, this may be accomplished without any surface preparation, by the addition of composite resin of the the same shade as that of the bis-acrylic resin used. Excesses which still may exist on the cervical can be removed with a #12 scalpel blade. (Fig. 25h) 7. Analyze, adjust and photograph the mock-up With the mock-up in position, the initial evaluation is performed by the dentist. Some aspects should be evaluated, such as the tooth length, width and its relationship to the lips, face and other elements. At that point, phonetic tests should also be performed and occlusal as well as aesthetic adjustments as needed.16 (Fig. 26 e 27) The second analysis must be carried out by the patient. Prior to that, the patient must be informed that bis-acrylic resin is monochromatic and that while the teeth are joined together, this will not be the case in the final rehabilitation. The mock-up serves to present the possible aesthetic and functional results, as well as the morphological features which may be obtained with the rehabilitation so as to add something tangible to the aesthetic rehabilitation planning, that the patient can see and experience before any procedure is performed within the patient’s mouth.16 In front of a mirror, the patient has the opportunity of evaluating the preliminary result and propose minor changes to the mock-up, that may even be performed immediately provided that it is clinically possible and that it does not compromise the aesthetic rehabilitation planning. If there are changes, it is recommended to carry out the impression with (high- and low-viscosity) addition silicone of the modified mock-up, which should then be stored and the information transfered to the lab technician. It is also necessary to take photos of the patient with the mock-up, repeating the photographic protocol explained earlier on in the chapter, in order to acquire as much comparative information of this trial as possible.

Figure 26.

Figure 27.

Figure 26. Evaluation at rest after installation of the indirect mock-up with bis-acrylic resin. Figure 27. Smile analysis after completion of the indirect mock-up with bis-acrylic resin.

119

It is not recommended that the patient leaves the office with the mock-up installed for several reasons, including the difficulty of hygiene, since the teeth are joined, which may lead to the formation of gingival inflammation if it remains in the mouth over a long period. In addition, there is a risk of interference from the opinions of others, during the process, by people who do not understand the clinical stages and its nuances, ending up issuing negative and impertinent opinions, which may lead the patient dropping out of the treatment. The mock-up is now mandatory in the execution of ceramic veneers, since it is an excellent tool for optimizing periodontal surgery (Fig. 28) and hence for further rehabilitation (Fig. 29a-h). The mock-up holds a key role in the difficult task of defining the necessity or not of for tooth preparation in the making of ceramic veneers. It serves to reveal the exact location where it is required to perform a small or a large reduction of the tooth structure. In Figure 30 it is possible to observe the presence of a slightly buccal left lateral incisor and an extremely fine direct mock-up, with a small chipping on the mesial edge. This situation ultimately confirms the precise location of any future reduction. Therefore we may conclude that the mock-up also occupies a role as a reduction guide, especially for prepless ceramic veneers or those with minimal reduction.

Figure 28.

Figure 29a.

Figure 29c.

Figure 29e.

Figure 29d.

Figure 29f.

Figure 28. Appearance after healing of the gingivoplasty for correction of gingival contour. Figure 29a-h. Final result after installation full ceramic veneers without preparation.

120

Figure 29b.

Figure 29g.

Figure 29h. Photography performed by Dudu Medeiros.

121

Figure 30a.

Figure 30b.

Figure 30c.

Figure 30d.

Figure 30e.

Figure 30f.

Figure 30g.

Figure 30h.

Figure 30i.

Figure 30j.

Figure 30. Initial appearance, which reveals the presence of discolored teeth, incisal edge of tooth 22 worn and 21 slightly proclined (a-b); incisal view confirming slight proclination of the tooth 22 (c); appearance after preparation of the direct mock-up with composite resin in the teeth 21 and 22 (d); detail which reveals the presence of an area with enhanced brightness on the mesial vertical edge demonstrates the presence of tooth structure at this location (e); aspect of the composite resin mock-up after removal of the tooth 22. Note that there was perforation of the mock-up for the absence of composite resin (f); after reduction in mouth of this vertical edge, impression taking and preparation of the working model were performed which will later be used for making the ceramic veneer of tooth #22 (g); aspect after cementation fragment of tooth #21 and veneer of tooth #22 (h); and final smile (i). Ceramist responsible: Leonardo Bocabella.

122

CONCLUSION REFERENCES

Guided by aesthetic principles and combined with a group of essential tools such as the photographic protocol, precise wax-up and mock-up, the aesthetic rehabilitation planning is carried out in a predictable and individualized manner, along with the establishment of an ideally universal aesthetic planning, relieving thereafter the unsuitable intuitive ability of the professional in this process. It is evident that the time spent on these steps generates time saving in the try-in phase of the veneers and minimal stress on the doctor-patient relationship, achieving ones expectations without major difficulties.

1. Bohnenkamp DM, Garcia LT. Repair of bis-acryl provisional restorations using flowable composite resin. J Prosthet Dent. 2004;92(5):500-2. 2. Burns DR, Beck DA, Nelson SK; Committee on Research in Fixed Prosthodontics of the Academy of Fixed Prosthodontics. A review of selected dental literature on contemporary provisional fixed prosthodontic treatment: report of the Committee on Research in Fixed Prosthodontics of the Academy of Fixed Prosthodontics. J Prosthet Dent. 2003;90(5):474-97. 3. Calamia JR, Levine JB, Lipp M, Cisneros G, Wolff MS. Smile design and treatment planning with the help of a comprehensive aesthetic evaluation form. Dent Clin North Am. 2011;55(2):187-209. 4. Christensen GJ. Important clinical uses for digital photography. J Am Dent Assoc. 2005;136(1):77-9. 5. Davis NC. Smile design. Dent Clin North Am. 2007;51(2):299-318, vii. 6. Decurcio RA, Cardoso PC, Rodrigues DC, Corrêa EJB, Borges GJ, Sulaimen AMM. O uso do mock-up na otimização e precisão do resultado da cirurgia plástica periodontal. Clín – Int J Braz Dent. 2012;8(1):74-85. 7. Essen SD. Digital imaging in dentistry. Todays FDA. 2011;23(6):62-8. 8. Goodlin R. Photographic-assisted diagnosis and treatment planning. Dent Clin North Am. 2011;55(2):211-27, vii. 9. Hatjó J. Anteriores: a beleza natural dos dentes anteriores. São Paulo: Santos; 2008. 10. Hutchinson I, Williams P. Digital cameras. Br J Orthod. 1999;26(4):326-31. 11. Llop DR. Technical analysis of clinical digital photographs. J Calif Dent Assoc. 2009;37(3):199-206. 12. Lutke G. Beyond the basics in digital photography. Todays FDA. 2012;24(3):55-7, 59. 13. Machado AW, Leite EB, Souki BQ. Fotografia digital em ortodontia. Parte IV: Sugestão de equipamento. J Bras Ortodon Ortop Facial. 2004;9(52):323-7. 14. Machado AW, Oliveira DD, Leite EB, Lana AMQ. Fotografia digital x analógica: a diferença na qualidade é perceptível? R Dental Press Ortodon Ortop Facial. 2005;10(4):115-23. 15. Machado AW. O que há de novo em fotografia digital? R Dental Press J. Orthod. 2010;15(2):20-3. 16. Magne P, Belser UC. Novel porcelain laminate preparation approach driven by a diagnostic mock-up. J Esthet Restor Dent. 2004;16(1):7-16; discussion 17-8. 17. Masioli MA, Masioli DLC, Damazio WQ. Fotografia digital na clínica diária. eBook XXV CISOP. São Paulo; 2007. 18. Masioli MA. Fotografia odontológica. Vitória; 2005. 19. McLaren EA, Garber DA, Figueira J. The Photoshop Smile Design technique. Part 1: Digital dental photography. Compend Contin Educ Dent. 2013;34(10):772-6. 20. McLaren EA, Schoenbaum T. Digital photography enhances diagnostics, communication, and documentation. Compend Contin Educ Dent. 2011;32(4):36-8. 21. Medeiros D. Click Dudu Fotografia Odontológica & Marketing. São José; 2013. 22. Morris M. Digital photography: your modern communication and marketing tool. Dental Economics. 2009;99(3). 23. Oliveira JP, Martins MF. Fotografia intraoral. São Paulo: Santos; 2004. 24. Paredes V, Gandia JL, Cibrian R. Digital diagnosis records in orthodontics: an overview. Med Oral Patol Oral Cir Bucal. 2006;11(1):E88-93 25. Robinson FGL, Chamberlain JA. Masking technique of cast for diagnostic waxing of labial veneers. J Prosthet Dent. 2007;97(1):56-7. 26. Sandler J, Murray A. Manipulation of digital photographs. J Orthod. 2002;29(3):189-94. 27. Shagam J, Kleiman A. Technological updates in dental photography. Dent Clin North Am. 2011;55(3):627-33, x-xi. 28. Shorey R, Moore K. Clinical digital photography: implementation of clinical photography for everyday practice. J Calif Dent Assoc. 2009;37(3):179-83. 29. Snow SR. Assessing and achieving accuracy in digital dental photography. J Calif Dent Assoc. 2009;37(3):185-91. 30. Trevisan F, Scanavini MA, Maltagliati LA, Gonçalves RR. Adaptações em câmera digital compacta para obtenção de fotografias intrabucais. R Clin Ortodon Dental Press. 2003;1(6):81-6.

123

SECTION II. BEFORE

OPTIMIZATION OF THE Aesthetic AND FUNCTIONAL RESULTS

chapter 5.1

Orthodontics as a differential for pretreatment ceramic veneers Juliana Romanelli

multidisciplinary dentistry which interacts with virtually all specialties, whether directly or indirectly. Oral rehabilitations can be extremely conservative when orthodontics is incorporated into the planning, from extensive treatments to the preparation of a single ceramic veneer. The evolution of cosmetic dentistry has been based on, among other things, the search for naturalness in the work to be performed and the maximum preservation of dental structures. The proposal of minimally invasive treatments, and even without tooth preparations, has been well addressed and discussed in the literature.9,19,20 Many are the approaches from orthodontics for optimizing the results of the restorations in aesthetic areas,21 which include the betterment of the surrounding soft tissues, approaches of which clinicians and rehabilitating specialists often are unaware, which reduces the possibility of more comprehensive planning. The predictability, beauty and longevity of ceramic works is strongly related to their correct planning. Ceramic veneers, especially for their delicate thickness, deserve due attention as to the positioning of the teeth from various angles, especially when considering the need for subtle reductions, inherent to this technique. Poorly positioned teeth may condemn the indication of veneers, changing the treatment option to full crowns and involve the possibility of endodontic treatments. Prior repositioning of the teeth can prevent these unwanted procedures and provide the desired conservative or even the elimination of preparations in most rehabilitation cases, positively changing the prognosis of involved teeth.15 The transition zone,8 composed of the cervical region of the prosthetic restoration and adjacent soft tissues, also had its importance uplifted with the advent of the supragingival preparation as well as at the level of the gingiva.9 The frequency of retreatments in dental practices accompanied by complaints of inflamed gingival margins of prosthetically-restored teeth lead the rehabilitation specialist to seek in orthodontics, through rapid orthodontic extrusion (ROE), a way in which expose the subgingival preparation, so that the teeth may then be retreated in the proper manner.13,16 With respect to the entire work, the gingival architecture which directly composes the patient’s smile has been studied for a long time. Accordingly, the gingival architecture should obey the leveling harmony, seeking to mimic the design sketched out by the cervical and incisal levels of the anterior teeth in relation to the curvatures of the upper and lower lips.2,4,9 This contour can, if non-existent, be constructed by way of simple orthodontic leveling, prior to the rehabilitation. In cases where there are injuries with bone loss and, consequently gingival within this aesthetic region, slow orthodontic extrusion (SOE) can rebuild this architecture even the red aesthetics, principally with regard to the limitations or asymmetries in the heights of the interdental papillae.5,14,18 The long treatment time, characteristic of orthodontics, and usually the patient’s main complaint, may be abbreviated when it is solely performed within the region to be rehabilitated. This may be considered minimalistic orthodontics,14 ranging from 6 to 12 months with results only to the composition of the rehabilitation treatment, and not malocclusion, when present. This concept should be extremely well clarified to the patient, 128

INTRODUCTION

Orthodontic treatments have become increasingly indispensable in the context of

because the election of the partial treatment should be a shared responsibility with the patient who will have the appliance installed and still have the possibility to opt for a total correction. In some situations, the malocclusion,  is the very cause of the trauma that leads to the loss of tooth structure (gingival recession, abfraction, enamel crazing and/or the incisal edge, etc.), thus the proposal for minimalistic orthodontic treatment should be discarded from the very beginning. The most requested forms of orthodontic preparation for aesthetic rehabilitation, for presenting the most significant benefits will be addressed in this chapter and may be

ORTHODONTICS APPLIED TO AESTHETICS

viewed in the illustrations and/or within each clinical case.

In order to present results with excellent aesthetic finishing, there are some strategic orthodontic movements to be performed prior to the restorations. These maneuvers are quite predictable and in most cases very simple. Such procedures may improve, encourage or even make possible the preparation of ceramic veneers. For orthodontics to be recognized beyond the standard occlusal correction, it objectively follows the most significant movements or orthodontic techniques, be those of a short duration, targeted towards a prosthetic approach, beyond their orthodontic indications and benefits. It is worth noting that these approaches demonstrate the opportunities provided by orthodontics, even when it does not coincide with the best aesthetic solution, some situations do involve limitations inherent to cases in which ones optimal movements are restricted, as in the case of vertical incisal leveling. LEVELINGS Vertical gingival leveling This being the most suitable form of vertical leveling in the pursuit for the harmony of a smile, principally when it involves aesthetic restorations of the gingival smile. The concept of gingival architecture is comprehensively addressed in Section II, of Chapter 5.2. In summary, it should be based on the cervical contours of the maxillary canines and central incisors, where their zeniths should be symmetrical and positioned 0.5 mm to 1.5 mm more apically in relation to the respective lateral incisors.10 This is where minor variations of the canine, slightly above the height of the central incisor are considered harmonic. The construction of this architecture through orthodontics in patients without any osseous or gingival defects becomes an extremely simple procedure, performed only with the correct positioning of brackets (utilizing braces). This positioning should preferably be designed prior to bonding, whre the heights are predetermined from the gingival to the incisal. In most current techniques, the starting point should be the canine, whose height of bonding should initially be determined. Then the following heights of the remaining teeth 129

will be calculated towards the central incisor, respecting the triangular shape with an inverted base between the heights of the cervical of the canines, lateral and central incisors4 (Fig. 1a). The accuracy of the heights varies according to the orthodontic technique and should respect the height/diameter of the crown.3 If orthodontics opts to use a technique of sequential acetate aligners (eg, Invisalign®, USA), its planning should involve that architectural condition during the gingival leveling. Case 1 involved a patient seeking rehabilitation with veneers, but presented gingival recession throughout the anterior region (Fig. 1b). She was previously submitted to root coverage surgery throughout the anterior-superior region, although the right side did not obtain the same degree of success as the left side (Fig. 1c). The passive auto-ligating device (Damon Clear,® Ormco, USA) elected was initially installed in a passive manner, for occlusal reorganization (Fig. 1d). After the occlusal leveling, still at an early stage, the brackets of teeth #13, #12 and #11 were purposely repositioned more gingivally (during different appointments, not in the same activation, being that they are sequential), which promoted the extrusion of the anterior right segment, obtaining the leveling of the cervical and papilla, not fully achieved through the coverage surgery. In addition to the vertical movement in the incisal direction, tooth #11 also had its long axis corrected because it presented mesial tilting of the crown and distal tilting of the root. The existing height difference between the maxillary centrals could then be verified, dissimula-

Figure 1a.

Figure 1b.

Figure 1c.

Figure 1d.

Figure 1a. Gingival vertical leveling. Figure 1b. Initial image with gingival recession. Figure 1c. Results of the gingival surgery with significant improvement on the left side. Figure 1d. Orthodontic appliance installed.

130

ted by the inclination of tooth #11 (Fig. 1e). The appliance was removed, the preparations for ceramic veneers were carried out (Fig.1f), and the porcelain restorations were installed (Fig. 1g). The case was followed up for 12 months (Fig. 1h). The premise for orthodontic leveling of this case was gingival vertical, to increase the harmony of the patient’s smile composition for the preparation of veneers. This change may be observed when comparing the initial and the 12-month contention phase (Fig. 1i-j). Nevertheless, blended to the proposal of this case, a minor slow orthodontic extrusion was carried out with the intention of also leveling the heights of the interdental papillae obtained by the symmetry of the alveolar bone crests brought about by the extrusion. Regarding the type of orthodontic appliance chosen for the gingival leveling, both fixed appliances as well as aligners may be used with a high degree of success without any restrictions.

Figure 1e.

Figure 1f.

Figure 1g.

Figure 1h.

Figure 1i.

Figure 1j.

Figure 1e. Result of the gingival leveling, and axial improvement in the central incisors. Figure 1f. After orthodontics, the preparations for ceramic veneers. Figure 1g.Veneers installed after the established leveling. Figure 1h. Case follow-up at 12 months. Figure 1i. Initial smile, after gingival surgery. Figure 1j. Final Smile with 12 month follow-up.

131

Vertical incisal leveling This is not to be the ideal orthodontic planning for rehabilitation, beyond the fact that its indications are even being restricted. For this leveling, the incisal harmony is what guides its accomplishment. In that, the line that touches the edges of the canines and incisors should be parallel to the curvature of the lower lip.4,9 Based on this design (Fig. 2a), the incisal vertical leveling is then formatted by the orthodontic treatment, when indicated. There is no report on this leveling as of a protocol for the aesthetic phase of rehabilitation. In this case, the result will not always present harmony within the cervical region and in the smile composition, since it depends upon the proportionality of the heights of the crowns for the same to occur within the gingival region. However, this is an alternative in cases where there may be inherent patient limitations. These various limitations can be physical or personal, such as the inability to undergo gingival plastic surgery (recontourings) and the inability of to accep tooth preparations beyond those compromised, often indispensable to achieve an excellent result. If the smile height is favorable to the case, and does not expose the gingival region, this becomes a fairly acceptable option to be considered. In case 2, the patient only presented the tooth #21 to be rehabilitated although a slope existed which was inasmuch gingival as it was occlusal (anteroposterior and vertical) in the anterior region. The patient’s complaint was both anterior crowding and the darkening of the restoration of the tooth #21 (Fig. 2b). If the treatment was accomplished directly by aesthetic rehabilitation, there would be a need for extremely invasive preparations in most of teeth, and the risk of endodontic treatment for tooth #22. Due to the objection of most adult patients with respect to the use of fixed orthodontic appliances, the selected appliances (and properly indicated) for this treatment were the sequential acetate aligners (Invisalign®, USA), completely aesthetic, removable and comfortable. The posterior occlusion did not display relevant issues; the anterior region merely presented crowding, as much in the lower as the superior arch, and a moderate deep bite (Fig. 2c), with the central incisors verticalized in relation to the lateral incisors and the canines extremely palatinized (Fig. 2d-e). Two distinct approaches were proposed for the patient, with planning that featured virtual set-ups, through the use of a software (ClinCheck®, Invisalign®, USA). In the first, and more commonly indicated, leveling takes place from the gingival margins. However, after the orthodontic stage, part of the restorative treatment would involve tooth #21, porcelain fragments on the canines and reduction of the mesial of tooth #11, as well as its preparation and restoration using a ceramic veneer. In the second planning, orthodontic leveling was accomplished only by the incisal edges, and in the most conservative manner. The only tooth to be involved in the restorative treatment would be #21, as was the intent of the patient from the beginning. The patient opted for the latter planning, acknowledging that it would be less harmonious, but more conservative. The result presented an orthodontic treatment which exactly achieved the expectation of the patient and permitted the restoration of tooth #21 with a ceramic veneer and an adequate design established by the incisal edges of the anterior teeth (Fig. 2f). 132

The bite was finished with an adequate ammount of overlap (Fig. 2g), and the inclinations of the incisors and canines along the arch became harmonic (Fig. 2h-i). The initial smile exhibiting half-open mouth showed discrepancies along the long axis and inclinations of both the maxillary as well as the mandibular teeth (Fig. 2j), an improvement seen in the final photo (Fig. 2k). The reasonably low position of the upper lip while smiling, observed in this last photo, favored the fact of not having gingival harmony in the composition of the final aesthetics. As in the previous case, this treatment could also be performed with fixed appliances of a variety of techniques, and the success rate would have been the same.

Figure 2a.

Figure 2b.

Figure 2c.

Figure 2d.

Figure 2e.

Figure 2f.

Figure 2g.

Figure 2h.

Figure 2i.

Figure 2j.

Figure 2k.

Figure 2a. Vertical incisal leveling. Figure 2b. Initial image, in which the vertical gap may be verified, in addition to tooth #21 to be rehabilitated. Figure 2c. Initial frontal intraoral view in occlusion with anterior crowding highlighted. Figures 2d-e Mid right and left profile views showing lingualized canines, and central incisors upright in relation to the lateral incisors. Figure 2f. Final result with ceramic veneer solely of the tooth #21. Figure 2g. Anterior final in occlusion demonstrating a suittable amount of overlap and the improvement of discrepancies in the positions of the teeth. Figures 2h-i Finalization in the middle left and right profile, which shows the harmony of the inclinations of the teeth after orthodontics. Figures 2j-k. Initial and final smile with mouth half open, showing the improvement obtained with orthodontic treatment followed by rehabilitation of the tooth #21.

133

Occlusal leveling by buccal This is a fundamental approach which respects the minimally invasive wear assumption for the preparation of teeth, suitable for ceramic veneers. Occlusal leveling eliminates discrepancies in the anteroposterior direction of tooth positioning,  in addition to the rotations on the axis of each tooth. The purpose of this maneuver is to align the centers of the crowns of the teeth in an occlusal view, inside the perimeter of the arch (Fig. 3a). In the vast majority of the cases, the leveling is achieved from the perspective of the buccal surfaces, respecting the difference in volume inherent in each type of tooth. Dental crowding is characteristic of the occlusal slope and realignment allows for this treatment to be as conservative as possible, within a rehabilitative proposal. When the teeth present this change (Fig. 3b), the reduction is more invasive in order to compensate for the excesses and promote leveling. Therefore, the use of orthodontics prior to the rehabilitation treatment becomes extremely important, to avoid this reductions. What follows are two clinical cases (cases 3 and 4) inwhich orthodontics was included in the treatment planning. Both cases which showed a significant occlusal uneveness were treated with sequential acetate aligners (Invisalign®, USA). The benefit achieved with orthodontics was decisive for the indication of ceramic veneers in the restorative treatment. Case 3 shows an absence of occlusal leveling with a deep bite, where the maxillary central incisors were found lingually and the maxillary lateral incisors, proclined. (Fig. 3c-e). The planning of the maxillary arch targeted realigning this imbalance, which in turn reflected in the improvement of the deep bite. Along the lower arch, the canines were significantly mesially inclined while crowding between the incisors showed to be moderate (Fig. 3f). This situation promoted interferences both in the movements of protrusion as well as lateralization, eliminating the protective guides. In this case, the planning of the lower arch involved mild intrusion of the incisors, concomitantly with leveling, to aid in the elimination of the deep bite. The treatment was performed in nearly a year, using 20 aligners, and the final result achieved all the desired goals as well as producing a sound equilibrium of the buccal surfaces of the teeth (Fig. 3g-j) and elimination of the deep bite; the last of which being very important for the longevity of rehabilitations with veneers which may be seen when comparing the before and after treatment results (Fig. 3k-l). This case, even though unfinished, fullfiled its planning through the use of ceramic veneers and fragments. The stone model demonstrates the design of the gingival recontouring and the veneers to be fabricated (Fig. 3m-n). Nearly the whole rehabilitation with veneers would be carried out without tooth reduction, through addition. Preparations would only be necessary in this case in the maxillary central incisors within the areas of retention, to better accommodate the veneers.

134

Figure 3b.

Figure 3a.

Figure 3c.

Figure 3d.

Figure 3e.

Figure 3f.

Figure 3g.

Figure 3h.

Figure 3i.

Figure 3j.

Figure 3k.

Figure 3l.

Figure 3m.

Figure 3n.

Figure 3a. Occlusal alignment based on the center axis of the teeth. Figure 3b. Occlusal unevenness. Figures 3c-e. Smile from the front, half right and half left profiles, highlighting the deep bite and divergent inclinations between lateral and central incisors. Figure 3f. Lower crowding with canines mesially inclined. Figures 3g-j. The case completed with the same views from the beginning, for further verification of the result. Figures 3k-l. Initial and final intraoral frontal view showing the elimination of the deep bite and completely leveled teeth. Figures 3m-n. Stone models demonstrating the planning of the case, and the small addition of porcelain, for carrying out a successful treatment.

135

Case 4 also shows an upper and lower crowding situation with similar characteristics to that of the previous case, alhtough the bite is now crossed in the middle region, and there exists a top relation in the anterior region (Fig. 4a-c). The patient’s complaint, in addition to the positioning of teeth, involved the shape of the teeth, rounded and relatively short, promoting a rather infantile look (Fig. 4d). The top bite, despite having the inverse characteristics of a deep bite presents contact interferences and laterality in the anterior teeth. As in the previous case, the protection guides were impaired, and the rehabilitation without the optimal repositioning of the teeth left the prognosis of treatment uncertain. The planning with Clincheck® (Invisalign®, USA), with which the end of the treatment may be previewed before the fabrication of the aligners, gives the orthodontist various alternatives to be more conservative, ie less invasive or brief, until a choice is made to have the aligners manufactured accordingly. In this case, planning only looks towards the aligning and leveling of the teeth for the preparation of the veneers, without the concern for a full correction of the midline deviation or of the canine guide. Details of which would already be corrected by the aesthetic rehabilitation, greatly minimizing the orthodontic tre-

Figure 4a.

Figure 4b.

Figure 4c.

Figure 4d.

Figure 4e.

Figure 4f.

Figure 4g.

Figure 4a-c. Initial intraoral images with upper and lower crowding, along with a top bite. Figure 4d. Original rounded shape of the teeth. Figures 4e-g. End of orthodontic phase.

136

atment time and allowing for the choice for a more abbreviated planning than would have been necessary. The treatment took up 13 months, and the result can be seen in Figures 4e-g. The format of the arches had also been improved, which benefits the stability of the new occlusion (Fig. 4h-k). The wax-up demonstrated no need for reductions for the prosthetic preparation (Fig. 4l), since the shape and position of the teeth would allow for the preparation of the veneers solely through an increase in their volume. The fragility of the veneers may be checked in Figures 4m-n, with the completion of the prosthesis at the level of the gingiva, with an enamel finish. The final outcome was successful in all of its proposals. The increased tooth length enabled the desired overlap in addition to the new, more rectangular tooth shape, solving the initial complaint of the patient (Fig. 4o-q). The choice of treatment with aligners in these cases were made strictly by the patients, although the fixed appliance is widely used for this type of leveling.

Figure 4h.

Figure 4i.

Figure 4j.

Figure 4k.

Figure 4l.

Figure 4m.

Figure 4n.

Figure 4o.

Figure 4p.

Figure 4q.

Figures 4h-k. Upper and lower occlusal photographs, initial and late orthodontic phase. Figure 4l. Diagnostic wax-up. Figures 4m-n Ceramic veneers loose and positioned in the stone model showing the preparations at the gingival level. Figures 4o-p. Intraoral images of installed porcelain restorations. Figure 4q. Smile showing the modification of tooth shape.

137

Lingual occlusal leveling This is a proposal rarely requested, although it is definitely an option in cases with anatomical irregularities on the buccal surfaces of the crowns. It is very common to carry out this leveling in aesthetic retreatment when the proposal is to replace old composite restorations in crowded teeth with porcelain, whether it be veneers or contact lenses. The uneveness is also occlusal like the previous, whereas the lingual or palatal surfaces are better preserved which prove to be superior guides for successful leveling. Similarly, the restoration will be carried out only on the buccal aspect, although the orthodontic treatment will be guided by the lingual surface. Case 5, utilized as an example, has come for retreatment, both orthodontic and aesthetic. This patient reported the following history of treatments before attending the clinic: showed severe maxillary crowding, and for correction had been subjected to rapid orthodontic treatment, whereby the patient’s anterior superior teeth were reduced on the proximal surfaces as well as the adjacent teeth. Still, there was recurrence in the crowding after some time, but the proposal given to the patient at that time involved using composite resin veneers for compensation of the crowding. The result merely camouflaged the real situation of poorly positioned teeth, although leveling was promoted through the use of the direct veneers. When the patient arrived at the dental practice, she was looking for a solution to the consistent irritation and spontaneous bleeding in the papillae region. The existing situation presented strong contact points and long and narrower teeth (Fig. 5a-c), produced by the

Figure 5a.

Figure 5b.

Figure 5c.

Figure 5d.

Figure 5e.

Figure 5f.

Figure 5a-c. Initial intraoral images. Figure 5d. Upper occlusal initial image, in which can be seen vestibular leveling obtained with additions of resin. Figures 5e-f. Virtual planning through the ClinCheck® (Invisalign®, USA), initial and final views.

138

narrowing of the space between the teeth and roots, which resorption the alveolar crest. This resorption resulted in the maintenance of shorter papillae, with an average of 5 mm from the ridge height to the contact point.22 From the upper occlusal view (Fig. 5d) the actual positioning of the teeth and the amount of resin used to offset this slope could be seen. The treatment chosen for this case was the use of sequential acetate aligners (Invisalign®, USA), and the planning through the alignment of the palatal surfaces was ordered, beyond the gap between the teeth, to achieve a superior accommodation of the papillae. The beginning and the end of the virtual planning may be observed in Figures 5e-f. Throughout the orthodontic treatment, the teeth were slightly separated, and the resins became more evident on the buccal surfaces (Fig. 5g), which were to be ground at the end of this phase, respecting the original axes of the teeth (Fig. 5h), and replaced with ceramic veneers, without the need for compensations (Fig. 5i-j). With the diameters of the teeth reestablished, and the contact points well determined, the papillae may, thereafter, be accommodated at a more incisal height, favorable for the prevention of hyperplasia and bleeding. In this particular case, the use of Clincheck® (Invisalign®, USA) for the planning greatly assists in the leveling of the lingual surfaces. A fixed apparatus could have accomplish the treatment, but not as quickly or as easily, requiring excessive resin removal at the very beginning could possibly promote an initially unfavorable aesthetic condition. Another alternative would be through the use of steel wire bends on the fixed appliance, which would not result in such precise leveling.

Figure 5g.

Figure 5h.

Figure 5i.

Figure 5j.

Figure 5g. During orthodontics, teeth apart so that the original mesiodistal diameter could be recovered. Figure 5h. Upon accomplishing the orthodontic phase, the resin reduction and veneer preparations, with leveling performed by the palatine surfaces. Figures 5i-j. Ceramic veneers installed with space for accommodation of the papillae and occlusal leveling.

139

ORTHODONTIC EXTRUSION Orthodontic extrusion may be defined as the movement of a tooth towards eruption, from a tensioning with virtually no resistance, as would occur in its very own eruption. This is a maneuver actually grounded in this movement, such that it was initially called a forced eruption.6 Considered a non-invasive, predictable and biological procedure,12 this technique presents extremely satisfactory results in the maintenance or improvement of the “transition zone”,8 in pursuit of naturalness in the completion of the clinical case, turning out to be the differential factor in the treatment. According to Garber,5 the natural aspect occurs when the soft tissue profile presents the same three-dimensional shape as the contralateral tooth. This rearrangement of the gingival architecture, with the proposed mirroring at the healthy side, may be obtained with two different orthodontic extrusion proposals. Rapid orthodontic extrusion (ROE) and slow orthodontic extrusion (SOE) as their actual names suggest, differ by speed, beyond the amount of force with which the movement is performed. Jointly, these variants will determine the amount of periodontium which will accompany the tooth.7 These two variations of movement are described below with their respective indications. Rapid Orthodontic Extrusion Some cases come up against unfavorable conditions for implementing the preparation, such as retreatment in subgingival preparations, presence of carious lesions extended to the root or even horizontal root cracks very close to the cervical height. All of which are conditions that may compromise the tooth, the prosthesis to be installed or the future gingival contour. A very affordable solution to correct this problem is by modifying the height of the preparation exposing the defect, carried out through ROE, which draws the tooth in the occlusal direction, with a heavy force at short intervals, causing the periodontal fibers to break away. The tooth is extruded until the unfavorable condition is exposed, and then the fibers are naturally reinserted at a new height. The red aesthetics is unchanged, for there is no tissue, or bone, or gingival augmentation in this case.7,13,14 This maneuver avoids the subgingival preparation in order to reach the defect. Therefore, in cases with less favorable defects, there will not be any invasion of the biological width in the preparation step, which would lead to gingival recession. Even when there is risk of invasion of the biological space, where the margin of the prosthesis ends in free gingiva, the tooth may be minimally extruded, and the preparation will be completely exposed, greatly reducing the chance of contamination within the prosthesis-tooth interface, common to subgingival preparations. In these cases, traction is often capable of leading to the ceramic margins remaining in enamel, maintaining the superior quality of its adhesion. Slow Orthodontic Extrusion When there is deficiency in the gingival architecture, especially when comparing an element to its contralateral, SOE can return the lost structure and favor the gingival aesthetics 140

of the restoration, allowing for a more natural appearance. For this version of the technique, there is both osseous as well as gingival tissue gain. The underlying bone architecture has been considered fundamental to the predictability and guiding of the interproximal soft tissue contour.18 Among the many benefits encountered through the use of this technique, two should be highlighted. The first of which is the formation or reestablishment of the interdental papillae, through the possibility of reconstruction of the alveolar bone crest, in a predictable manner,17,18 promoting support for the nutrition and maintenance of this gingival triangle. The other is the optimal quality of the bone formed by the slow extrusion, ie, a highly differentiated bone.16 For the latter to occur, the premises of light forces, long intervals between appointments and correct timing for post-extrusion contention must be respected. A movement carried out slowly and with light forces promotes tensioning of the periodontal ligament, which elongates the fiber bundle and induces osteoblasts to deposit new bone in areas of the alveolar socket where periodontal retention exists.11 For the formation of bone to be able to accompany the movement rate, slow extrusion should occur with an average of 1.0 mm per month. Slow extrusion has another indication besides improvement of the gingival architecture of the tooth to be restored. Since the early 90s, it has been found that even when the tooth was condemned, manipulation of this element could substantially improve the environment where the implant would be installed, provided that it presents a certain amount of periodontium adhered to the root in the region of the loss.17 The post-extrusion stabilization comes as the third important point to ensure the success of the extrusive treatment. After the movement is completed, the tooth should be immobilized, still accompanied by the orthodontic appliances, so that tissue accommodation and maturation of the newly created bone may occur. After a determined period, it may be rehabilitated (or removed, if an implant is indicated). A period of time with an acceptable “safety margin” for bone maturation is 3 months, during which the tooth, and consequently the periodontium will remain for rehabilitation. On the other hand, if the indication of the treatment involves extraction and implant replacement, six months would be sufficient. The difference lies in the fact that, with the removal of the tooth, the periodontium is also extinguished, and the bone should be completely solidified, to receive the implant with full maturity. Some authors, such as Brindis & Block,1 consider that the time of extrusion, the intervals between each one and the stabilization period depends directly on the type of bone and periodontium, that is, on the resistance imposed by the structure. To illustrate both extrusion techniques, case 6 exhibited tooth #21 with an indication for retreatment due to the complaint of consistent gingival irritation (Fig. 6 a). Small irregularity was found within the tooth-prosthesis interface, in a slightly subgingival preparation (Fig. 6b). The tooth was initially subjected to traction with SOE, for tissue gain (Fig. 6c), envisioning a possible gingival recession inherent to prosthetic preparations. Now with this safety margin (overcorrection), ROS was carried out, for the subgingival preparation to be exposed (Fig. 6d-e), leaving the tooth in much more favorable conditions for retreatment. In this last movement, the gingival height did not change as there was no tissue gain, as a result of the heavy forces and short intervals. 141

This is a movement performed exclusively with fixed appliances both with rapid extrusion, as well as with the slow extrusion technique. The treatment proposal of sequential aligners may occur in similar situations, where cervical leveling takes place, when some teeth are to be repositioned with their cervical height apically inclined. However, when there exists a necessity to modify the preparation height of gaining gingival tissue for rehabilitation, the technique of clear aligners has its limitations and is not indicated.

Figure 6a.

Figure 6b.

Figure 6c.

Figure 6d.

Figure 6a.Initial image with the tooth #21 for retreatment. Figure 6b. Initial periapical X-rays, with evidence of irregularities in the mesial surface of the finishing of the prosthesis. Figure 6c. Slow orthodontic extrusion, with augmentation of the gingival margin and papillae. Figures 6d-e. Rapid orthodontic extrusion, with the maintenance of gingival height and exposure of the former preparation.

142

Figure 6e.

FINAL CONSIDERATIONS ON ORTHODONTIC MOVEMENTS

Orthodontics is unquestionably integrated to rehabilitation treatment. Despite being clinically well-founded and supported by the literature, it is underused and in most cases, not even chosen. There are two principal situations inwhich rehabilitator does not request the orthodontic therapy. The first and most consistent of which occurs when the existing leveling allows for an above average finishing of the case and the cost effectiveness of using braces will be minimal or zero, increasing the time of treatment and the patient’s expenditures unnecessarily. This statement is valid for the most delicate finishings, as are ceramic veneers and contact lenses, as well as for more invasive preparations, such as prosthetic crowns. The second, often unchallengeable reason, is the unwillingness of the patient and/or rehabilitator themselves to extend the treatment time due to the use of braces. For several reasons, often involving ignorance with respect to the subject of the urgency of any of the parties involved to finalize the case, orthodontics is not always regarded as being beneficial. This concept should be principally modified from the perspective of the dentist which will carry out the planning. When they actually can see and believe in the improvement in many respects for the patient and for the longevity of the work, the patient will also believe, with the same intensity as the professional. Some less recurring situations are really restrictive, and not should not be argued, such as the financial aspect, functional limitations of the case and the lack of security or skill of the involved professionals. For the patient to be involved with the concept of this type of treatment, the choice of using an appliance is very extremely abrangent, with some exceptions already mentioned. Today, Orthodontics can reach the various demands of patients particularly in this field of aesthetics. The clinical knowledge regarding the various orthodontical proposals has been growing, but not rarely are the techniques discredited as a result of a lack of information. Constant updating must be part of clinical life, especially for the rehabilitator, aimed at producing long-lasting and conservative work with excellence in its completion, directly proportional to the natural aspect obtained. The possibility to choose the leveling which enables the orthodontist to offer resources to the multidisciplinary planning, will circumvent some case limitations. An excellent example of this is in vertical incisal leveling, which is not a procedure that promotes harmony in the gingival area in most of the times, which is usually fundamental for the construction of the smile. In other words, it is not always the leveling according to the premises of the aesthetic treatment. However, it is an alternative for minimal harmony when facing certain restrictions. In addition to several levellings, focused on conservative tooth reduction proposals and gingival aesthetics, orthodontic extrusions are also an excellent resource for achieving naturalness. The orthodontic forced eruption brings a certain naturality to the completion of the case. Altough they are relatively simple techniques, they are relentless in their demands. For the tooth to be rehabilitated, both slow as well as fast extrusion may be used, provided that the amount of movement to be performed is observed, ie, the amount of root that will 143

remain inserted after completion of the orthodontic therapy must be sufficient enough to receive the prosthesis lastingly and have its function preserved. The periodontal biotype is a question that may influence the effectiveness of the extrusion results. The thinner it is, the greater is the possibility of encountering gingival recession in more extensive movements. In some cases, it would be of great interest to begin the therapy using a connective tissue graft for changing this biotype. In treatments where there is no possibility of minimalistic orthodontics, where requiring a complete orthodontic therapy is needed, extrusion is usually carried out at the beginning of the treatment. This order of priorities is a function of the necessity for accommodation and tissue maturity after manipulation of the periodontal tissues. While maturation takes place, the rest of the treatment is to be carried out. The intent of this chapter is merely to clarify and demonstrate to the dentist, in general, the range of options that this interaction between specialties may offer. A well-coordinated team with balanced knowledge may reap amazing fruits from this partnership, and

I can not fail to mention the people who have contributed to my learning in view of orthodontic therapy targeted towards cosmetic dentistry and those who have worked in the clinical cases presented here. Dr. Bruno Godoy, who, in addition to multidisciplinary planning, excellently conducted the prosthetic part for completion of case #1. The oral rehabilitation team of the Oral Atelier Dental Practice, for introducing me to the search for a minimally invasive dentistry, by way of conducting the rehabilitative phase of the other cases presented (cases 2 to 6).

144

ACKNOWLEDGEMENTS

quite often more simply than not.

REFERENCES

1. Brindis MA, Block MS. Orthodontic tooth extrusion to enhance soft tissue implant aesthetics. J Oral Maxillofac Surg. 2009;67(11):49-59. 2. Câmara CALP. Estética em Ortodontia: Parte I. Diagrama de Referências Estéticas Dentais (DRED). R Dental Press Estét. 2004;1(1):40-57. 3. Carinhena GF. Colagem de bráquetes em zênites para o sorriso. In: Carinhena GF. Ortodontia autoligada: mecânicas contemporâneas do sistema autoligado passivo. Protocolos de tratamento. São Paulo: Napoleão; 2014. p. 55-95. 4. Fradeani M. Reabilitação estética em prótese fixa: análise estética. São Paulo: Quintessence; 2006. 5. Garber DA. The aesthetic dental implant: letting restoration be the guide. J Am Dent Assoc. 1995;126(3):319-25. 6. Ingber JS. Forced eruption. Part I: A method of treating isolated one and two wall infrabony osseous defects: rationale and case report. J Periodontol. 1974;45(4):199-206. 7. Janson M. Ortodontia em adultos e tratamento interdisciplinar. 2a ed. Maringá: Dental Press; 2010. 8. Joly JC, Carvalho PFM, Da Silva RC. Reconstrução tecidual estética: procedimentos plásticos e regenerativos periodontais e peri-implantares. São Paulo: Artes Médicas; 2010. 9. Kyrillos M, Moreira M, Calicchio L. Um olhar cuidadoso sobre a beleza. In: Kyrillos M, Moreira M, Calicchio L. A arquitetura do sorriso. São Paulo: Quintessence; 2012. p. 69-149. 10. Magne P, Belser U. Restaurações adesivas de porcelana na dentição anterior: uma abordagem biomimética. São Paulo: Quintessence; 2012. 11. Mantzikos T, Shamus I. Forced eruption and implant site development: soft tissue response. Am J Orthod Dentofacial Orthop. 1997;112(6):596-606. 12. Morr T. Improving soft tissue form around implants via forced eruption. Quint Dental Tech. 2005;28:112-28. 13. Pontoriero R, Celenza F Jr, Ricci G, Carnevale G. Rapid extrusion with fiber resection: a combined orthodontic-periodontic treatment modality. Int J Periodontics Restorative Dent. 1987;7(5):30-43. 14. Romanelli J. Excelência nas finalizações estéticas e periimplantares. In: Callegari A, Dias, RB. Especialidade em foco: beleza do sorriso. Nova Odessa: Napoleão; 2013. p. 216-45. 15. Romanelli J. O uso do Invisalign® e seu planejamento virtual (ClinCheck®, USA) na adequação de casos para reabilitação com prepares conservadores. Dicas. 2013;2(4):54-7. 16. Romanelli J. Reabilitações estéticas gengivais compostas pela extrusão ortodôntica. Rev Dental Press Estét. 2014;11(1):4659. 17. Salama H, Salama M. The role of orthodontic extrusive remodeling in the enhacement of soft and hard tissue profiles prior to implant placement: a systematic approach to the management of extraction site defects. Int J Periodont Restor Dent. 1993;13(4):312-34. 18. Salama H, Salama MA, Garber D, Adar P. The interproximal height of bone: a guidepost to predictable aesthetic strategies and soft tissue contours in anterior tooth replacement. Pract Periodontics Aesthet Dent. 1998;10(9):1131-41; quiz 1142. 19. Scopin de Andrade OS, Kina S, Hirata R. Concepts for an ultraconservative approach to indirect anterior restorations. Quintessence Dent Technol. 2011;34:103-19. 20. Scopin de Andrade OS, Romanini JC, Hirata R. Ultimate ceramic veneers: a laboratory-guided ultraconservative preparation concept for maximun enamel preservation. Quintessence Dent Techol. 2012;35:29-42. 21. Smallwood TW. Invisalign and porecelain: the contemporary restorative powerhouse. J Orofac Alpha Omegan. 2009;102(4):148-51. 22. Tarnow DP, Magner AW, Fletcher P. The effect of the distance from the contact point to the crest of bone on the presence or absence of the interproximal dental papilla. J Periodontol. 1992.;63(12):995-6.

145

chapter 5.2

periodontal plastic surgery Rafael de Almeida Decurcio | Amin de Macedo Mamede Sulaimen | Leandro de Carvalho Cardoso

The overwhelming evolution of Aesthetic Dentistry is accompanied by the relevant appreciation of interdisciplinary works. Today, it is unthinkable to treat patients within a single discipline, shortsighted, without proposing at least a broad overview of the real possibilities of treatment. In the realm of aesthetic restorations, perio-implant dentistry is a major player, from the evaluation of the aesthetic principles of gingiva and their convergences, to actions aimed at the optimization of the results. Also on multidisciplinarity, periodontics and implant dentistry have merged, to act on similar problems, inwhich what was merely changed is the substrate, teeth or implants. In this manner, rehabilitative interventions must necessarily be proposed after a thoughtful and planned periodontal-implant intervention, either by pragmatic prevention of diseases and consequent promotion of the longevity of the treatments performed, or by the application of surgical techniques that aim to improve

With the understanding that the ceramic veneers are part of the treatments performed at the end of the rehabilitation process and that infectious and/or periodontal inflammatory lesions should undergo previous intervention, the entire approach in this chapter will be in treating discrepancies as opposed to ideal periodontal aesthetic principles. For this, knowledge of the periodontal biotype becomes essential to the understanding of the processes related to the individualization of the surgical therapies proposed for the regularization of implant-aesthetic periodontal discrepancies.20 Although there are reports in the literature on the subdivision of the periodontal biotype into three conditions,32 it is wiser to subdivide it into two types, keeping in mind that the intermediate periodontal biotype at times suffers from misguided interventions due to diagnostic errors, which leads to unsatisfactory results, so it should always be considered thin.4 Kan & cols22 demonstrated that the observation from the probing of the gingival sulcus is a safe an accurate method of identifying the periodontal biotype. When the lines of the periodontal probe were not visible in the gingival sulcus, it was identified as having a thick biotype and, when visible, it was said to be thin. Given the difficulty and subjectivity of the evaluations and different techniques to define the type of periodontal biotype, didactically, the authors adopt the pattern set by Olsson and Lindhe,36 that is, the periodontal biotype is divided into two types (Table 1): 1. flat and thick: presenting a wide range of keratinized mucosa, with dense, fibrous tissue, short and wide papillae, and underlying flat and thick bone; and 2. thin and scalloped: featuring a small strip of keratinized tissue, thin tissue, with long, narrow papillae and thin and scalloped underlying bone.36 These periodontal biotypes and their antagonistic features provide clinical explanations of the discrepancies presented, that hinder the aesthetic results of the rehabilitation proposals. Similarly, they offer clear conditions towards the individualization of the surgical treatment and predictability over the implemented therapies.39 148

PERIODONTAL BIOTYPE

the current clinical condition and optimization of the proposed aesthetic results.

According to their morphological characteristics, thick biotypes are associated with flat and short gingival papillae and square-shaped teeth.36 (Fig. 1a-f) Such a condition becomes relevant when establishing a new and different dental format for a rehabilitation proposal, confering antagonism to the gingival and dental morphologies. Surgical intervention should invariably follow the pattern of the established dental form; that being, the mock-up has an essential role in this step. When a squared tooth shape is chosen, the periodontal biotype may remain slightly thicker, with flat and short papillae and bulkier marginal tissue without any loss of naturality to the result.

Figure 1a.

Figure 1b.

Figure 1c.

Figure 1d.

Figure 1e.

Figure 1f.

Figure 1. Patient with thick periodontal biotype from the initial smile photography (a) with separated lips (b). Photography after periodontal surgery guided by the mock-up matching the final gingival contour obtained (c). After rehabilitation, final photographs of the patient with lips apart in occlusion (d) and with the black background (e) displaying the final gingival contour obtained, along with the final smile photograph showing the resolution of the gingival smile and achieved harmony (f).

149

In clinical situations in which the periodontal biotype is too thick (Fig. 2a-u), establishing an ovoid-shaped tooth or mainly triangular requires greater invasive surgical interventions. This occurs in cases of clinical crown tissue lenghtening with a more extensive removal of volume, especially osseous, and a new contour of the coronal marginal bone, to offer an aspect of a smoother transition between the parts of the rehabilitation, gingiva and tooth. By analogy, in cases of gingival recession, the natural maintenance or rehabilitative establishment of squared teeth impose the need for the surgical incor-

Figure 2c.

Figure 2a.

Figure 2b.

Figure 2d.

Figure 2e.

Figure 2f.

Figure 2g.

Figure 2i.

Figure 2j.

Figure 2k.

Figure 2l.

Figure 2h.

Figure 2. Case of patient with thick biotype. Initial photographs of the face: frontal smile (a) and lateral smile (b).Close-up initial mouth: Frontal smile (c), frontal at rest (d), lateral smile (e-f) and initial upper arch (g). Photographs of periodontal surgery: acrylic indirect mock-up in place as a lengthening guide (h), flap raise-up (i) flap detached (j) and bur in place to perform the osteotomy (k). Photographs after clinical crown lengthening: close-up of smile (l), frontal face with smile (m) and lateral (n). After periodontal surgery were performed the preparations, impressioning and making of the ceramic veneers. Detail of the ceramic veneers on the stone model (o). Final photographs of the patient with the cemented veneers: Frontal with lips at rest (p), dentolabial frontal smile (q) and laterals (r-s), and face with frontal smile (t) and lateral (u).

150

poration of a higher volume of marginal tissue compared to ovoid or triangular shaped teeth. Another condition of enormous relevance in relation to thick biotypes is the beneficial sum of their morphological characteristics to the rehabilitation. Voluminous, fibrous tissue, consequently less transparent,22 favors subgingival prosthetic preparations, as well as the positioning of ceramic veneers at the same level. This becomes critical with dark coronary or root substrates requiring greater coronal reduction or a superior ability of masking the darkened cervical margin.

Figure 2o.

Figure 2m.

Figure 2n.

Figure 2p.

Figure 2q.

Figure 2r.

Figure 2s.

Figure 2t.

Figure 2u.

151

Recent studies adopting the cone-beam computerized tomography have confirmed a positive correlation between facial soft tissue thickness and bone lamina.10,13 In other words, a thick periodontal biotype is associated with a thicker lamina bone labial.10 Thin periodontal biotypes are associated with long, narrow papillae and triangular-shaped teeth.36 In this biotype the analytical concept is the inverse of that which was previously presented. Surgical interventions must be thoroughly careful due to the thin and delicate thickness of the gingival tissue and the constant presence of scalloped areas of bone tissue, that produce disastrous results when handled without their due parsimony. In contrast, surgical interventions for clinical crown lengthening and dimensional readjustments for ceramic restorations allow for conservative access without flap lifting, known as the flapless technique.5,21 (Fig. 3a-d) Another highly relevant factor for the thin biotype is the transparency of the marginal tissue,22 which presents the undesireable chromatic conditions of the root browning cyanotic halo of the metal margin of restorations, cementation lines and others. The analysis of these situations is of fundamental importance to the establishment of the rehabilitation processes,considering that a thin biotype requires the carrying out of preparations and/or ceramic supragingival positioning or at least, at the level of the gingival margin. Sometimes surgical interventions for readjusting the marginal tissue volume are necessary to avoid aesthetically satisfactory ceramic results accompanyed by aesthetically unpleasant gingival results, either through maintenance of the marginal darkening, or by the appearance of gingival recession due to the thickness of the gingival tissue.26

Figure 3a.

Figure 3b.

Figure 3c.

Figure 3d.

Figure 3. Case of patient with thin biotype. Initial intraoral photograph of the patient with gingival recession (a) and photo after connective graft within the region of the canines (b). Close-up photo of the central incisors evidence of the long, narrow papilla and the triangular teeth, characteristic of this biotype (c). Photo after the cementation of the veneers showing the harmony of the gingival contour obtained in patients with thin biotype(d).

152

Table 1. Periodontal biotype.20

FINE AND SCALLOPED

Dense and fibrotic soft tissue

Thin soft tissue

Broad range of keratinized tissue

Reduced range of keratinized tissue

Short and wide papillae

Long and narrow papillae

Thick, flat underlying bone

Thin and scalloped underlying bone (high frequency of dehiscence and fenestration)

Attachment loss associated with the presence of periodontal pocket

Attachment loss associated with the presence of recession of the gingival margin

Contact area in the middle/cervical third

Contact point in the incisal/occlusal third

Square-shaped teeth

Triangular-shaped teeth

GINGIVAL RECONTOURING

PLAN AND THICK

As described in Chapter 2, ideally, an aesthetically pleasing gingival contour occurs when the gingival zenith of the maxillary central incisor is vertically symmetrical to the canine and when it ranges from 0.5 mm to 1.5 mm more apically to the lateral incisor. In this conformation, the zenith positions of anterior superior teeth are characterized as the vertices of an imaginary triangle with its base towards the apical, which confirms the balance of the gingival components. The absence of this harmony, verified by the absence of the imaginary formation or the inversion of this triangle, suggests the surgical correction of this tissue contour for optimization of the aesthetic result. (Fig. 4a-h)

Figure 4a.

Figure 4b.

Figure 4c.

Figure 4d.

Figure 4e.

Figure 4f.

Figure 4g.

Figure 4h.

Figure 4. Case of patient operated by the flapless technique, initial intraoral photography in occlusion (a) and of Illustration of the development of the technique: preparation of the direct composite resin mock-up (b-d) and its use as a surgical guide for the clinical crown lenghtening (e-f). Photo immediately after surgery (h)and after healing and cementation of the veneers(i).

153

The presence of a high smile line and disharmonic gingival contours suggests to the clinician the need for cosmetic periodontal surgery. However, surgical interventions are dependent upon the patient’s desire, and do not always carried out according to the case presented. (Fig. 5a-e)

Figure 5a.

Figure 5b.

Figure 5d.

Figure 5c.

Figure 5e.

Gingival recession is defined as the apical migration of the gingival margin in relation to the cement-enamel junction (CEJ).47 According to Baker & Seymour,3 the etiology of these lesions is accompanied by inflammation produced by the accumulation of biofilm or toothbrushing trauma, found in populations with both a high as well as a low oral hygiene index. Undoubtedly, the presence of gingival recession makes a smile less attractive and frequently the complaint of patients. However, it may also be associated with functional problems such as cervical hypersensitivity, as well as carious and noncarious cervical lesions, and a greater likelihood of biofilm accumulation.35 There are several techniques with the purpose of root surface coverage, the predictability of which is primarily associated to the proximal bone height.30 Other factors such as the amount of keratinized gingiva, gingival thickness, presence/absence of cervical lesions, height and width of the papillae, may influence the most appropriate technique decision for the coverage of exposed roots.43 154

GINGIVAL COVERAGE

Figure 5. Patients demonstrating a high smile line and disharmonious gingival contour (c). Frontal view of the veneer of tooth #11 completed without surgical intervention (d-e). Dental technician: Murilo Calgaro.

Gingival recessions are more prevalent in thin biotypes than in thick biotypes; thus  surgical interventions are often associated to the replacement of areas of tissue lost by the installation of infectious and/or traumatic inflammatory processes.1 The aesthetic planning of clinical conditions that involve the presence of gingival recession depends on integrating periodontal and restorative concepts for achieving harmonious results. In these situations, the restorative planning is critical to establishing the optimal positioning of the future prosthetic margin, prior to the surgical procedure.48 Regardless of the technique used, the clinical success of the coverage is defined by the complete coverage of the root surface, with a probing depth of less than 3 mm, absence of gingival inflammation, and tissue volume and coloration compatible with the adjacent areas, so that the treated region is indistinguishable from other regions that do not present recessions.28 (Figures 6a-x)

Figure 6a.

Figure 6b.

Figure 6c.

Figure 6d.

Figure 6e.

Figure 6f.

Figure 6. High smile line revealing gingival disharmony (a). Intraoral view showing gingival recession of the tooth 13 and changed positions of the gingival zenith in teeth #11 and #12 (b). Determining the lengths of the clinical crowns of the six anterior teeth with a millimeter probe (c-h). Delimitation of the new gingival zenith outline #15c scalpel blade (i). Detail of the gingival collar to be removed of teeth #11 and #12 (j). Scaling and planning for disinfection and for adequation of volume for later adaptation of the graft on tooth #13 (p). Suture with tensioning of the gingival tissue towards the coronal aspect (s). Intraoral aspect after cementation of full ceramic “contact lenses” veneers without preparation with feldspathic porcelain (see chapter 5.3) (v) and the final smile (x).

155

Figure 6g.

Figure 6h.

Figure 6i.

Figure 6j.

Figure 6k.

Figure 6l.

Figure 6m.

Figure 6n.

Figure 6o.

Figure 6p.

Figure 6q.

Figure 6r.

Figure 6s.

Figure 6t.

Figure 6u.

Figure 6v.

156

Figure 6x.

AESTHETIC CLINICAL CROWN LENGTHENING

According to Joly, De Carvalho & Da Silva,20 surgical interventions of clinical crown lengthening (osteotomy/osteoplasty procedures ) for the thick biotype are dependent upon flap elevation for exposure of the bone crest, since osteoplasty (bone removal in thickness) is necessary to optimize bone architecture and improve the adaptation of the soft tissue in the cervical region. (Table 2) In such cases, and in conjunction with restorative procedures, the healing time, which typically ranges from 90 to 180 days, should be strictly respected for the proper maturation of the cervical soft tissues. However, depending upon the extent of the periodontal surgery, it can reach up to one year.42 (Fig. 7 e 8) When there is no related restorative treatment, the osteotomy limit is determined by the location of the CEJ, so that there is no undesireable exposure of the root portions, which may generate deleterious clinical consequences, such as dentin hypersensitivity and noncarious cervical lesions. In the case of thin and intermediate biotypes, the osteoplasty may be dismissed depending upon the delicate thickness of the natural bone, and osteotomy should be performed exclusively with manual instruments. With the use of the appropriate micro-chisels able to be introduced into the gingival sulcus without trauma to the soft tissue, flap elevation may be disregarded, which is known as the flapless technique. Considering the impossibility of the direct visualization of the extent of the osteotomy, periodontal probing becomes critical before, during and after the surgery, to confer the reestablishment of the biological width.20 (Table 2) (Fig. 7 e 8)

Table 2. Comparisons between two augmentation techniques of aesthetic clinical crowns.

FLAPLESS

CONVENTIONAL

IINDICATION

Fine and intermediate Biotypes

Thick biotypes

SUTURES

Absent

Present

DISCOMFORT AFTER SURGERY

Minimal

Moderate

VISUAL ASPECT OF THE CICATRIZATION

Fast

Slow

SURGICAL TIME

Short

Long

SURGICAL TECHNIQUE

Meticulous and delicate

Large and conventional

OSTEOTOMY

Small

Medium to high

Either by predominantly periodontal motivation, or in association to restorative procedures, aesthetic clinical crown lenghtening must be exhaustively discussed with the patient, for safe decision-making, given the nature of this definitive procedure. Again, the direct or indirect restorative trial starts with this decision-making process, providing early and provisionally the new tooth dimensions of the proposed rehabilitation.

157

Figure 7c.

Figure 7a.

Figure 7b.

Figure 7d.

Figure 7e.

Figure 7f.

Figure 7g.

Figure 7h.

Figure 7i.

Figure 7j.

Figure 7k.

Figure 7l.

Figure 7. Frontal facial and initial profile analysis (a-b). Lack of maxillary teeth exposure at rest (c). Initial smile revealing the presence of multiple diastemata, gingival exposure greater than 3 mm in the posterior region, lack of parallelism between the incisal line and the line passing through the lower lip and reverse incisal curve (d). Initial upper and lower intraoral photographs identifying a thick “classic” biotype in the posterior region (Table 2) and the presence of short papillae (e-l). Determining the distance Interpupillary and confirmation of ideal measures in the mock-up (m-n). Mock-up in position guiding the incision of the new gingival contour (o). Detail of the gingival collar after the removal of the mock-up at the right side (p). Appearance after complete removal of the mock-up (q). Protocol sequence of the removal of the gingival collar with appropriate curettes (r-v).

158

Figure 7n.

Figure 7o.

Figure 7m.

Figure 7p.

Figure 7q.

Figure 7r.

Figure 7s.

Figure 7t.

Figure 7u.

Figure 7v.

Figure 8a.

Figure 8b.

Figure 8c.

Figure 8. Positioning of the millimeter probe before the osteotomy (a-b). Osteotomy with microchisels by the flapless technique (c). Verification of the amount of bone removal with millimeter probe (d). Flap raise-up in the posterior region (e). Positioning of the diamond point to perform osteoplasty (f). Appearance after bone volume reduction (g). Suture limited to the area which was submitted to the flap raise-up (h). 120 days after healing and packing of the first retraction cord for impression (i). Intraoral and smile photographs immediately after cementation of the prepless maxillary ceramic veneers (j-k). Cementation sequence of mandibular ceramic veneers with minimal tooth reduction (l-q). Final intraoral, smile and facial appearance (r-t).

159

Figure 8d.

Figure 8e.

Figure 8f.

Figure 8g.

Figure 8h.

Figure 8i.

Figure 8j.

Figure 8k.

Figure 8l.

Figure 8m.

Figure 8n.

Figure 8o.

Figure 8p.

Figure 8q.

Figure 8r.

Figure 8s.

160

Figure 8t.

161

is confused with a high smile line. All patients who possess gingival smile present high smile line, although the opposite is not true, since the gingival smile is represented by an exposition of the gingiva greater than 3 mm (Fig. 9) Several treatment options are available for correcting the gingival smile,24 the best of which is based on the etiology. Dentoalveolar extrusion of the maxillary incisors leads the gingival margin towards a more coronal position and causes

EXCESSIVE EXPOSURE OF TOOTH AND GINGIVA

INCREASED EXPOSURE OF INCISIVE DURING REST

NORMAL LIP LENGTH

NORMAL EXPOSURE OF INCISIVE DURING REST

SHORT SUPERIOR LIP

NORMAL LENGTH OF CLINICAL CROWN

SHOR CLINICAL CROWN

DIFFERENCE BETWEEN THE HARMONY OF THE ANTERIOR AND POSTERIOR OCLUSAL PLANES

HARMONIOUS OCLUSAL PLAN

INCISAL WEAR

EXTRUSION OF INCISIVES

VERTICAL MAXILLARY EXCESS (VME)

EXTRUSION OF INCISIVE

HIPERACTIVE SUPERIOR LIPS

WITHOUT WEAR

ALTERED PASSIVE ERUPTION (1 OR MORE TEETH)

GINGIVAL HYPERPLASIA

Quadro 1. Schematic drawing of the treatment options of the gingival smile according to clinical characteristics.

Figure 9c.

Figure 9a.

Figure 9b.

Figure 9d.

Figure 9. Initial protocol photographs, smile and rest, revealing the presence of gingival smile, optimal exposure at rest and lingual inclination of anterior superior teeth (a-f). Incision of the new gingival contour guided by the mock-up with the ideal dimensions (g). Detachment of the gingival collar with a curette (h). view of flap raise-up (i). Detail of the repositioning of mock-up and and millimeter probe for evaluating the amount of tissue removed (j). Intraoral appearance after 120 days of clinical crown lengthening (k). Packing of retraction cords for impressioning and future manufacture of prepless ceramic veneers (l-n). Intraoral view after cementation of the ceramic veneers (o-p). Final smile (q). Final appearance of profile smile, detail of increased buccal volume after cementation (r) and final protocol (s) and artistic photographs (t-u). Dental technician: José Carlos Romanini.

162

GINGIVAL SMILE

Excessive maxillary gingival exposure is commonly referred to as a gingival smile. However, often, the gingival smile

Figure 9e.

Figure 9f.

Figure 9g.

Figure 9h.

Figure 9i.

Figure 9j.

Figure 9k.

Figure 9l.

Figure 9m.

Figure 9n.

Figure 9o.

Figure 9p.

Figure 9q.

Figure 9r.

Figure 9s.

163

Figure 9t. Fotografia realizada por Dudu Medeiros.

164

Figure 9u. Fotografia realizada por Dudu Medeiros.

165

excessive gingival exposure, this condition could possibly be associated with wear of the anterior teeth or an overbite. In the latter case, there is discrepancy between the occlusal plane of the anterior and posterior segments.The orthodontic intrusion of the elements involved, moving the gingival margin more apically, the periodontal surgical correction, with or without adjunctive restorative therapy, or an interdisciplinary intervention are the treatment options for this condition.6,12,15 Excessive growth of the maxilla in the vertical direction may lead to the association of the Elongated Face Syndrome.23,7 (Fig. 10) This increase occurs in the lower third of the face, and, unlike the extrusion of the maxillary incisors, there is no discrepancy between the occlusal plane of the anterior and posterior segments. Excessive gingival exposure in these cases occurs due to the presence of an occlusal plane relatively below the normal pattern, causing the lower lip to cover the edge of the incisors, canines and premolars.

Figure 9u. Photograph byFigure Dudu10. Medeiros.

Figure 10. Gingival smile caused by excessive growth of the maxilla in the vertical direction.

166

Regarding the upper lip, described in Chapter 2, with proportions lower than the default measure, the treatment options are plastic surgery, such as the elongation of the upper lip which is associated with rhinoplasty.24,29 In the cases of hyperactivity of the muscles responsible for the lip movement while smiling, some cosmetic procedures are available, such as silicone implantation in the vestibule bottom, surgical procedures in the muscles responsible for the upper lip mobility, and bioplasty, where polymethylmethacrylate is applied into the tissues. These two techniques were based on the same concept of incising the elevator muscle of the upper lip, or part thereof (the main muscle involved with the formation of the smile). According to the author, this procedure results in decreased elevation of the upper lip during smile.37 Recently, the application of botulinum toxin has been suggested for the treatment of hypermobility of the upper lip.40 Botulinum toxin is a simple, fast and effective method for cosmetic correction of the gingival smile. Mazzuco & cols27 cited other factors that consider the toxin as a first-line therapy, for its ease and safety during application, as well as its quick action, low risk and reversible effect. This ultimate factor is particularly interesting in cases where the orthodontic treatment or surgical procedure is recommended, by way of allowing the aesthetic effect prior to the invasive procedure. The emergence profile of the tooth is determined by the exit of the crown from the bone crest, which is considered completed when the tooth reaches the occlusal plane and enters into function. Associated with dental eruption, the soft tissues accompany this movement, and at the end of this process, the gingival margin migrates apically until it is located close to the CEJ (passive eruption). When the gingiva does not return to its original position, it earns its given name “altered passive eruption”. According to Isiksal,19 a short clinical crown and gingival excess are consequences of an altered or delayed passive irruption, which hampers the proper recession of the gingival tissue at the level of the CEJ. This condition has been classified into types and subcategories. The type indicates the amount of attached gingiva, and the subcategory, the relationship of the bone crest to the CEJ. In cases of passive eruption in the presence of excess soft tissue and bone tissue, the surgical approaches indicated are the conventional clinical crown lenghtening or the flapless techniques.21 When the aesthetic change of the smile is caused by increased vertical maxillary growth, various techniques can be recommended, from orthodontic intrusion to orthognathic surgery, but always giving priority to the aesthetic clinical crown lengthening and possible involvement with complementary restorative procedures. However, it is up to the patient to define the surgical option utilizing the mock-up as a facilitating tool in this decision-making process.The exclusion of orthognathic surgery as first choice stimulates the indication of a second option, which involves performing periodontal cosmetic surgery associated with ceramic laminates, which have proven satisfactory results even when facing limitations and difficulty in obtaining the optimal resolution.2 (Fig. 2) In such cases, some procedures, such as botulin toxin infiltration, are available which can supplement the actions for the treatment.17,34, 37,40,41

167

ased use of osseointegrated dental implants in totally or partially edentulous patients provided aesthetic advances in implant-supported rehabilitations, which has become a key factor in the success of implantology. Thus, some procedures, such as planning based on aesthetic fundamentals, set out in Chapter 2, the wax-up and mock-up, described in Chapter 3, and the production of radiographic and surgical guides have become mandatory, since the implant positioning is to be determined mainly by the future rehabilitation, rather than the conditions of the bone at the receiving site.16 From an aesthetic point of view, the presence of a suitable band of keratinized mucosa, combined with suitable gingival thickness prior to the implant installation, it is of paramount importance for the aesthetic result and longevity of the treatment, being that thicker gingival tissues certainly present better aesthetic results than thin gingival biotypes. The absence of this condition may involve difficult cleaning, greater accumulation of plaque, peri-implant gingival inflammation, gingival dehiscence with the simultaneous appearance of the metal of the implant and discrepancy of the apparent size of the homologous teeth.44 By analogy, even in immediate rehabilitating conditions, the effect of the transillumination of the metallic part of the implant may also occur due to the presence of fairly thin tissue which becomes aesthetically displeasing in the smile composition. This problem results from the gingival tissue being of an inadequate thickness or from a more apical positioning of the attachment level of the connective and bone tissues around the implant. The appearance of gingival “black holes” is another aesthetic problem which can result from the lack of keratinized tissue. It is about the absence of adequate papillary tissue at the gingival margin between the teeth, between teeth and implants, and between implants in the anterior segment. In addition to the need for the existence of keratinized tissue in quantity and quality, the correct positioning of implants in the edentulous space and respect for the distances (vertical and horizontal) between implants and teeth which is essential for maintaining the shape of the papillae. Grunder18 found that a distance of 5 mm between the contact point and the bone crest is required when an implant is placed adjacent to a tooth, for the complete filling of the papillary space to occur, similar to that which was already known about the distance between teeth.This study also postulated that the vertical positioning of the implant does not establish success in the process of the formation of the papilla, a factot later confirmed by Choquet et al.8 The difficulty in creating the papilla appears to be higher among implants, mainly whithin the aesthetic areas.14,15 Tarnow & cols46 have shown that the distance between two implants should be at least 3 mm. However, this distance between implants does not guarantee the formation of the papilla, it merely prevents further inter-implant bone loss. In another clinical study, Tarnow & cols45 found that a 2 mm to 4 mm height (average 3.4 mm) of soft tissue may be expected to cover the inter-implant crestal bone, a situation that should be considered in aesthetic regions when planning. There is concern about the optimal maintenance of the biological space and its clinical effects on peri-implant aesthetics. For teeth that have a cavity preparation and consequently the margin of the restoration is very close to the crestal bone, not respecting 168

IMPLANT IN THE AESTHETIC ZONE

The evolution of bioengineering, the technical and scientific advances and the incre-

the structures of the biologic width, insertion loss due to the inflammatory process takes place, triggered by the invasion of the biologic width. For implants, especially in aesthetic areas, where is required to place the platform at the level of the crest, loss of bone structure also occurs, in order to establish an adaptation of the structures that form the biologic width around implants.9 Thus, although the loss of bone that takes place around implants may be considered natural, it should be controlled and well understood, as the final aesthetic result will depend in a good part on the understanding of this phenomenon. It is important to be aware that this loss occurs threedimensionally, around 1 mm to 1.5 mm, and that the remaining bone should exist around the entire implant after the formation of the biologic width. If it does not occur, severe aesthetic problems may arise. The preliminary approach to the installation of implants includes the use of surgical guides which includes the mock-up. (Fig. 11a-x) Beyond that, when the elaboration of the treatment plan is needed for implant placement in areas with compromised dental elements is included, the professional must then pressupose the presence of bone and/ or gingival deformities. Whenever possible, the professional must focus their efforts on tissue preservation and prevention of possible defects, but, when they are present and they compromise the installation of the implants, reconstructive procedures should be performed prior to or at the moment of extraction.33

Figure 11a.

Figure 11b.

Figure 11c.

Figure 11.Initial facial analysis (a-c). Initial smile revealing the absence of lateral incisors, presence of deciduous canines and a posterior gingival smile (d). Initial intraoral aspect (e). Mock-up installed (f). Mock-up positioned guiding the incision for clinical crown lengthening (g). Aspect after the initial incision (h). Extraction of primary canines #53 and #63. (i). Positioning of the mock-up for guide pin installation (j). Using the countersink for proper adaptation of the implant in the cervical portion (k). Installation of the implant (l).Frontal and incisal view after installation of zirconia abutments (m-n). Smile after installation of provisional crowns (o-p).Appearance after preparation of canines (q). Veneers and crowns finalized and placed on the stone model (r). Final intraoral aspect (s). Final photographic protocol (t-v). Photographs by Dudu Medeiros.

169

Figure 11d.

Figure 11e.

Figure 11f.

Figure 11g.

Figure 11h.

Figure 11i.

Figure 11j.

Figure 11k.

Figure 11l.

Figure 11m.

Figure 11n.

Figure 11o.

170

Figure 11p.

Figure 11q.

Figure 11r.

Figure 11s.

Figure 11t.

171

Figure 11u. Photograph by Dudu Medeiros.

172

Figure 11v. Photograph by Dudu Medeiros.

173

In addition to proper planning and observation of the possible necessity of bone as well as gingival tissue adjustments, the surgical technique for implant installation is critical to the aesthetic success of the case. Aesthetic areas, namely the anterior maxillary area, requires a different surgical approach. The incision should avoid the area of the papillae, because it is a critical area, beyond being directed by the distance between the contact point and the bone, the healing process may be compromised.25 (Fig. 12a-x)

Figure 12a.

Figure 12b.

Figure 12c.

Figure 12d.

Figure 1e.

Figure 12f.

Figure 12g.

Figure 12h.

Figure 12i.

Figure 12. Initial smile revealing absence of the lateral incisor and the presence of diastemas (a). Initial intraoral aspect (b-e). Aspect of the area to be implanted after removal of the prosthesis (f). Aspect of the incision (g-i). Osteotomy with micro-chisels by the flapless technique (j). Circular incision with a scalpel (k). Drilling of the bone (l). Installed implant (Nobel Active®, Nobel Biocare) (m). Aspect after the installation of the provisional crown (n). Intraoral view after healing and subepithelial gingival graft on tooth #22 (o). Final intraoral aspect (p). Final photographic protocol (q-r).

174

Figure 12j.

Figure 12k.

Figure 12l.

Figure 12m.

Figure 12n.

Figure 12o.

Figure 12p.

Figure 12q.

Figure 12r.

175

2. Arnett GW, Bergman RT. Facial keys to orthodontic diagnosis and treatment planning. Part II. Am J Orthod Dentofacial Orthop. 1993 May;103(5):395-411. 3. Baker DL, Seymour GJ. The possible pathogenesis of gingival recession: a histological study of induced recession in the rat. J Clin Periodontol. 1976;3:208-219. 4. Caplanis N, Lozada JL, Kan JY. Extraction defect assessment, classification, and management. J Calif Dent Assoc. 2005 Nov;33(11):853-63. 5. Carvalho PFM, Silva RC, Joly JC. Aumento de coroa clínica estético sem retalho: uma nova alternativa terapêutica. Rev Assoc Paul Cir Dent. 2010;ED ESP(1):26-33. 6. Chiche GJ, Pinault A. Aesthetics of anterior fixed prosthodontics. Chicago: Quintessence; 1994. 7. Chiche GJ, Pinault A. Replacement of deficient crowns. J Esthet Dent. 1993;5(5):193-9. 8. Choquet V, Hermans M, Adriaenssens P, Daelemans P, Tarnow DP, Malevez C. Clinical and radiographic evaluation of the papilla level adjacent to single-tooth dental implants: a retrospective study in the maxillary anterior region. J Periodontol. 2001 Oct;72(10):1364-71. 9. Cochran DL, Hermann JS, Schenk RK, Higginbottom FL, Buser D. Biologic width around titaniun implants: a histometric analysis of the implanto-gingival junction around unloaded and loaded non submerged implants in the canine mandible. J Periodontol. 1997;68:186-98. 10. Cook DR, Mealey BL, Verrett RG, Mills MP, Noujeim ME, Lasho DJ, et al. Relationship between clinical periodontal biotype and labial plate thickness: an in vivo study. Int J Periodontics Restorative Dent. 2011;31(4):345-54. 11. Fradeani M. Estethic analysis: a systematic approach to prosthetic treatment. Chicago: Quintessence; 2004. 12. Fradeani M. Aesthetic rehabilitation in fixed prosthodontics. Chicago: Quintessence; 2004. 13. Fu JH, Yeh CY, Chan HL, Tatarakis N, Leong DJ, Wang HL. Tissue biotype and its relation to the underlying bone morphology. J Periodontol. 2010;81(4):569-74. 14. Garber DA, Salama MA. The aesthetic smile: diagnosis and treatment. Periodontol 2000. 1996;11:18-28. 15. Garber DA, Salama MA, Salama H. Immediate total tooth replacement. Compend Contin Educ Dent. 2001 Mar;22(3):210-6, 218. 16. Garber DA. The aesthetic dental implant: letting restoration be the guide. J Am Dent Assoc. 1995 Mar;126(3):319-25. 17. Gracco A, Tracey S. Botox and the gummy smile. Prog Orthod. 2010;11(1):76-82. 18. Grunder U. Stability of the mucosal topography around single-tooth implants and adjacent teeth: 1-year results. Int J Periodontics Restorative Dent. 2000 Feb;20(1):11-7. 19. Işiksal E, Hazar S, Akyalçin S. Smile aesthetics: perception and comparison of treated and untreated smiles. Am J Orthod Dentofacial Orthop. 2006 Jan;129(1):8-16. 20. Joly JC, Da Silva RC, Carvalho PFM. Reconstrução Tecidual Estética: procedimentos plásticos e regenerativos periodontais e peri-implantares. São Paulo: Artes Médicas; 2009. 21. Joly JC, Da Silva RC, De Carvalho PFM. Reconstrução tecidual estética: procedimentos plásticos e regenerativos. São Paulo: Artes Médicas; 2010. 22. Kan JY, Morimoto T, Rungcharassaeng K, Roe P, Smith DH. Gingival biotype assessment in the aesthetic zone: visual versus direct measurement. Int J Periodontics Restorative Dent 2010;30(3):237-43. 23. Kawamoto HK Jr. Treatment of the elongated lower face and the gummy smile. Clin Plast Surg. 1982;9: 479-89. 24. Levine RA, McGuire M. The diagnosis and treatment of the gummy smile. Compend Contin Educ Dent. 1997;18(8):75762~764. 25. Lorenzana ER, Allen EP. The single-incision palatal harvest technique: a strategy for aesthetics and patient comfort. Int J Periodontics Restorative Dent. 2000 Jun;20(3):297-305. 26. Maynard JG Jr, Wilson RD. Physiologic dimensions of the periodontium significant to the restorative dentist. J Periodontol. 1979 Apr;50(4):170-4. 27. Mazzuco R, Hexsel D. Gummy smile and botulinum toxin: a new approach based on the gingival esposure area. J Am Acad Dermatol. 2010;63(6):1042-51. 28. Miller PD Jr. Periodontal plastic surgical techniques for regeneration. In: Polson AL. Periodontal regeneration-current status and directions. Chicago: Quintessence; 1994. p. 53-70. 29. Miskinyar SA. A new method for correcting a gummy smile. Plast Reconstr Surg. 1983;72:397-400. 30. Modica F1, Del Pizzo M, Roccuzzo M, Romagnoli R. Coronally advanced flap for the treatment of buccal gingival recessions with and without enamel matrix derivate: a splith-mouth study. Periodontol 2000. 2000;71(11):1693-8. 31. Morley J, Eubank J. Macroaesthetic elements of smile design. J Am Dent Assoc. 2001;132(1):39-45. 32. Müller HP, Könönen E. Variance components of gingival thickness. J Periodontal Res. 2005 Jun;40(3):239-44. 33. Nemcovsky CE, Moses O, Artzi Z. Interproximal papillae reconstruction in maxillary implants. J Periodontol 2000 Feb;71(2):308-14. 34. Niamtu J 3rd. Botox injections for gummy smiles. Am J Orthod Dentofacial Orthop. 2008 Jun;133(6):782-3; author reply 783-4. 35. Novaes AB, Novaes Jr AB. Cirurgia periodontal com finalidade protética. São Paulo: Artes Médicas; 1999. 36. Olsson M, Lindhe J. Periodontal characteristics in individuals with varying form of the upper central incisors. J Clin Periodontol. 1991 Jan;18(1):78-82. 37. Peck S, Peck L, Kataja M. Some vertical lineaments of lip position. Am J Orthod Dentofacial Orthop. 1992 Jun;101(6):519-24 38. Peck S, Peck L, Kataja M. The gingival smile line. Angle Orthod 1992 Summer;62:91- 100; discussion 101-2. 39. Polack MA, Mahn DH. Biotype change for the aesthetic rehabilitation of the smile. J Esthet Restor Dent. 2013 Jun;25(3):17786. 40. Polo M. Botulinum toxin type A (Botox) for the neuromuscular correction of excessive gingival display on smiling (gummy smile). Am J Orthod Dentofacial Orthop. 2008 Feb;133(2):195-203.

176

REFERENCES

1. American Academy of Periodontology. Glossary of Periodontal Terms. 4rd ed. Chicago: The American Academy of Periodontology; 2001.

41. Polo M. Botulinum toxin type A in the treatment of excessive gingival display. Am J Orthod Dentofacial Orthop. 2005 Feb;127(2):214-8; quiz 261. 42. Pontoriero R, Carnevale G. Surgical crown lengthening: a 12-month clinical wound healing study. J Periodontol. 2001;72:8418. 43. Silva CO, Ribeiro-Júnior NV, Campos TV, Rodrigues JG, Tatakis DN. Excessive gingival display: treatment by a modified lip repositioning technique. J Clin Periodontol. 2013 Mar;40(3):260-5. 44. Strub JR, Gaberthüel TW, Grunder U. The role of attached gingiva in the health of peri-implant tissue in dogs. 1. Clinical findings. Int J Periodontics Restorative Dent. 1991;11(4):317-33. 45. Tarnow D, Elian N, Fletcher P, Froum S, Magner A, Cho SC, et al. Vertical distance from the crest of bone to the height of the interproximal papilla between adjacent implants. J Periodontol. 2003 Dec;74(12):1785-8. 46. Tarnow DP, Cho SC, Wallace SS. The effect of inter-implant distance on the height of inter-implant bone crest. J Periodontol. 2000 Apr;71(4):546-9. 47. Wennström JL. Mucogengival therapy. Ann Periodontol. 1996;1:671-701. 48. Zucchelli G, Testori T, De Sanctis M. Clinical and anatomical factors limiting treatment outcomes of gingival recession: a new method to predetermine the line of root coverage. J Periodontol. 2006 Apr;77(4):714-21.

177

chapter 5.3

tooth bleaching Jussara Bernardon | Rafael Decurcio | Paula de Carvalho Cardoso

Tooth bleaching is one of the most performed daily clinical procedures.7 Regarded as a prerequisite for aesthetic dentistry, especially when associated with treatments that require changes in smile architecture.5,39 For direct and indirect restorative treatments to be started, it is necessary that the patient is satisfied with the color of their natural teeth because it will remain in the “new” tooth arrangement. Such importance is due to the influence of the substrate color when ultrafine ceramic veneers are indicated2 or when you need to modify the tooth form, through the use of composite resin in specific locations of the crown, towards the improvement of the harmony of the smile. In other words, it is essential to obtain the shade desired by the patient for the teeth to be restored as well as for the teeth which will remain without restorations, before carrying out the restorative treatment. Shade matching of all substrates involved in this process is a condition which is part of the rehabilitation protocol with ceramic veneers, above all, it is characterized as an extremely conservative condition, because it provides less preparation of the naturally darkened teeth for shade matching, generally of a higher value than that of the ceramics installed in addition to maintaining a greater volume of enamel. Although all bleaching techniques available today are effective, a successful treatment is directly related to the etiological factor responsible for the discoloration.4,20,45 Naturally discolored teeth or those darkened by ageing respond satisfactorily and usually better to bleaching than those stained by intrinsic pigmentation, as caused by tetracycline and tooth fluorosis.4,25,27,29,41 In these cases, sometimes bleaching is merely not sufficient, and more invasive procedures may be necessary to restore the dental aesthetics through restorative procedures. Tooth bleaching involves the application of a carbamide peroxide (CP) or hydrogen peroxide (HP) based agent on the tooth structure. The dynamics of the bleaching process may be explained by the permeability of the dental structure to low molecular weight oxidative free radicals, from the degradation of these peroxides and their redox chemical nature.3,22,24 Thus, macromolecules of existing organic pigments in dentin are broken down into smaller molecules, which changes their configurations and hence their optical properties, resulting in lighter teeth.22,24 For bleaching vital teeth, bleaching agents of different concentrations may be indicated for supervised at-home use, in-office application or even through the association of both bleaching techniques. Given the various options, the dentist have questions when choosing the bleaching gel (substance and concentration) and the bleaching technique which will best meet each case. Therefore, the purpose of this chapter is to provide scientifically-based information on the behavior of different bleaching agents and techniques available, and so help the professional to make the right choice for the different situations of everyday dental practice.

180

BLEACHING AGENTS

Agents used in the different bleaching techniques are basically composed of carbamide peroxide or hydrogen peroxide.7,5 Although the chemical reactions of these bleaching agents look similar, they are not. Therefore, different behaviors of the tooth structure about color change, surface changes as well as tooth sensitivity may be expected when these bleaching products are used.7 Hence the importance of knowing the specifics of the chemical reaction of each bleaching agent, as well as to understand the reaction of the dental structures when they are used are necessary, in order to establish an effective bleaching protocol with minimal side effects. Carbamide peroxide upon contact with saliva and dental tissues, dissociates into urea and hydrogen peroxide, which, in turn, degrades into water and oxygen, which is the active agent responsible for the oxidation reactions involved in the bleaching process.15 When using a 10% carbamide peroxide based gel, only 3.6% hydrogen peroxide is available. It should be noted that even when carbamide peroxide based bleaching agents of a higher concentration, e.g. 37%, are used, the share of hydrogen peroxide is still low, around 13%.4 In addition to allowing to provide hydrogen peroxide in low concentrations, the mechanism of action of the carbamide peroxide neutralizes the pH of the oral environment and releases oxygen slowly.4 As the resulting hydrogen peroxide of reaction is caustic, the neutralization of the pH is of extreme importance, since it reduces possible changes to the tooth surface. Moreover, hydrogen peroxide is more unstable than carbamide peroxide, having a lower molecular weight, and breaks down more rapidly into water and oxygen,15 therefore requires less time to produce the desired action.19 Nevertheless, the need for a pH below 4.5 to maintain the stability and the absence of urea byproducts to neutralize the pH produce microscopic changes when applied on the tooth surface.14,24,25 Although microscopic changes to the tooth surface seem negligible at first, if we consider the increase in life expectancy to approximately 80 years, this seemingly unapparent microscopic wear, started at an early age, can become significant when elderly. In addition, greater diffusion of active oxygen via dentinal tubules, which may reach the pulp tissue is reported in histological studies. Therefore, when higher hydrogen peroxide concentrations are used, pulpal damage of greater intensity is reported.7,21 Considering that the concentration of the active substance of the bleaching agent is directly related to the intensity of the adverse effects,26 it is of paramount importance to be aware of the concentration of hydrogen peroxide of each commercially available bleaching agent (Quadro 1).

Quadro 1. Relationship of the hydrogen peroxide percentage in bleaching agents for home and in-office use.

BLEACHING AGENT 10% Carbamide peroxide

PERCENTAGE OF HIDROGEN PEROXIDE 3.6%

16% Carbamide peroxide

5.8%

37% Carbamide peroxide

13.3%

20% Hydrogen peroxide

20%

35% Hydrogen peroxide

35%

38% Hydrogen peroxide

38%

181

and available.31 Initially, satisfactory bleaching have been obtained using daily applications of 10% carbamide peroxide with the aid of a tray for a period of 8 h,18 though laboratory and clinical researches have shown that both the hydrogen peroxide as carbamide peroxide degrade rapidly in the first few hours of use: at 1 hour, the degradation of hydrogen peroxide is approximately 68%;1 and that of carbamide peroxide is higher than 50% in 2 hours.31,32 This finding demonstrates that existing bleaching agents may be used daily for a short period, regardless of the bleaching technique used. Thus, satisfactory bleaching has been achieved utilizing a short time interval: half an hour to 2-hour daily application. Clinical studies evaluating periods of less than two hours of daily use have reported color change similar to that obtained with the same bleaching products for 8 hours.8,30 Hence the safe modification in the at-home supervised bleaching protocol for using the bleaching for less than 2 hours daily. Cardoso & cols,8 even showed that daily use for only 15 minutes makes it possible to obtain satisfactory results. The decrease in contact time of the gel to the tooth surface also helped to further reduce the already low tooth sensitivity rates reported for at-home bleaching, especially when carbamide peroxide concentrations higher than 10% are used. Effective bleaching without adverse effects have become increasingly present.5 As it happens slowly and gradually, color change of the teeth may be tracked individually. Although time to obtain the desired bleaching is variable, an average of 2 to 6 weeks are required to complete the treatment.6,28 It should be noted that the initial color is crucial in defining this time. Therefore, bleaching A3 or darker teeth takes longer than bleaching A2 or lighter teeth. In order to obtain satisfactory results more rapidly, bleaching products with agents of a higher concentration have been developed. For supervised home bleaching, bleaching based on carbamide peroxide concentrations between 10% and 22% are frequently used by professionals. Although it seems logical that higher concentrations promote satisfactory results in less time, clinical studies evaluating the bleaching A3 or darker teeth reported similar treatment duration, between 4-6 weeks to achieve patients satisfaction, regardless of the concentration (10% CP, 16% CP and 22% CP) of the bleaching agent used in the home technique.6,34 What actually happens is a more rapid visualization of the discoloration by the patient, in the first week, when bleaching agents of higher concentration are used. However, after the third week there is no difference in color obtained through the use of different concentrations.6 Therefore, the final treatment time will not necessarily be shorter when higher concentration of bleaching are used. Additionally, the fact that Matis & cols32 demonstrated that the lower the concentration of the bleaching agent used, the most stable are the results, that is, bleaching products of a lower concentration, in addition to being as effective as those of a higher concentration, make possible the results to be more stable over the years. When the search was for faster results, the in-office bleaching technique was recommended. However, clinical and scientific evidence shows that there is no difference in the time of treatment required to achieve patients satisfaction when this technique is compared to that of the at-home bleaching technique.6 Initially, the use of 35% hydrogen peroxide-based bleaching agents for in-office application was intended to promote satis182

DENTAL BLEACHING TECHNQUES

In order for bleaching to occur, a minimum amount of bleaching agent must be active

factory bleaching in a single session. With this technique, after the retraction of soft tissue and carrying out a gingival barrier, the bleaching agent is applied on the labial surface of the teeth and maintained for approximately 45 minutes.5,33 When removing the product, color change is generally already noticeable by the patient. In such cases, bright teeth result from the action of the bleaching agent and tooth dehydration resulting from the relative isolation required to perform the technique. Thus, after dental rehydration, which can take up to 3 days, color reversal occurs and teeth appear less clear.4 In fact, the color after rehydration is actually reached in the bleaching session, which normally does not meet patient’s expectations, making it necessary for more bleaching sessions. To bleach teeth with initial color A3 or darker six sessions or more may be required to achieve patient’s satisfaction, depending on the case and the bleaching agent used.6,17 Weekly applications of the product are recommended due to the high concentration of hydrogen peroxide,33 requiring 6 weeks for patient’s satisfaction. Furthermore, the high concentration of hydrogen peroxide may cause high intensity tooth sensitivity, due to the diffusion of the product via dentinal tubules, reaching the pulp tissue.10,11,17,23,33 In such cases, analgesics may be required to facilitate the treatment. Even though there is not any longitudinal clinical research with a representative sample evaluating the pulp response to in-office bleaching, in situ studies have reported pulp necrosis in mandibular incisors when 38% HP was used.11 In addition to reversible (high intensity tooth sensitivity)23,33,38,42 or irreversible (pulp necrosis)11 pulp damage, clinical studies have reported that the low stability of bleaching obtained by the in-office technique with 35% to 38% hydrogen peroxide; after 6 months of treatment one may already perceive color reversal.17,36 A 37% carbamide peroxide-based bleaching agent has been commercially available for in-office use. When in contact with the tooth structure, 37% carbamide peroxide dissociates by approximately 13.3% hydrogen peroxide and 10% urea. The lowest concentration of HP in the product enables in-office daily applications of up to 45 minutes with a low risk of tooth sensitivity.16 Clinical studies have showed that applications for 6 consecutive days provided color change similar to that obtained with four weekly sessions of 38% HP.9 Another important factor is that these six applications may be carried out all on the same day. Besides satisfactory bleaching in just 1 day, or in 1 week (cases of applications in sequential days) of treatment, a clinical trial found that only 20% of the patients experienced mild tooth sensitivity, beginning after the fourth day of the consecutive application of the product.9 Although the product can be safely applied in daily sessions, the patient’s low tolerance threshold of pain of the may require alternate days of applications, which eliminates any painful symptomatology. Another advantage of using the 37% CP is the possibility of simplifying the application technique, being that the gingival barrier is not necessary, although the clinician may if deemed necessary. Thus, after the removal of soft tissue the product that requires no mixing is applied on the labial surface of the teeth. Although in-office bleaching has such advantages, as the rapid visualization of color change, the availability of time for the various in-office sessions for the patient may be considered disadvantageous, in addition to making the procedure most expensive. In order to make the procedure feasible for all patients, an alternative that has been well accepted by professionals is associating the bleaching techniques, combining the best characteristics of 183

in-office bleaching with the at-home bleaching.4,13 In-office sessions, using 37% CP or 38% HP for 45 minutes, are used concomitantly wih daily applications of 10% or 16% CP. Initially, an in-office session is performed with the goal of producing a noticeable color change after removal of the product. Then the color change continues to occur gradually through daily applications by the at-home technique and a second In-office session may then be carried out, in order to enhance the speed of the bleaching therapy. Daily applications for at-home use are maintained until the end of the treatment. Some of the advantages of associating bleaching techniques which may be cited are: satisfactory results in the shortest time; reducing the inherent sensitivity to the in-office bleaching; reducing the treatment costs, being that fewer in-office sessions will be necessary; and greater longevity of the bleaching will be

Establishing a single protocol for the bleaching treatment is totally impractical, given the different responses of bleaching agents when applied to the tooth structure. Despite being simple, there is a universal pursuit for having white teeth without any pain symptoms. Even though product characteristics may be influenced with the appearance of tooth sensitivity, from inherent characteristics of the patient, due to ones threshold of pain tolerance, psychological aspects, areas of dentin exposure and sensitivity prior to the beginning of treatment, are determining factors which can explain the appearance of the painful symptoms even when placebo gels are used in clinical research.12,21,40 Hence the need to carry out an accurate diagnosis, since the presence of tooth sensitivity can delay the start of treatment. In these cases, topical application of fluoride, fluoride mouthwash or treatment with the potassium nitrate and potassium oxalate based desensitizers are recommended prior to the start of the bleaching and, if possible, should be maintained throughout the tooth bleaching process.12 Even if desensitizing agents are present in all bleaching products currently available, the concentration of the product and the time it remains in contact with the tooth 37

structure may result in different pulp responses.21 Therefore, some strategies can be used to reduce tooth sensitivity rates prior, whether they are existent or not:

184

TREATMENT PROTOCOL

achieved.13

1. in cases of previous sensitivity, perform treatment with desensitizers (potassium oxalate, strontium chloride, potassium nitrate or fluorides) before whitening; 2. seal, initially, areas of exposed dentin with glass ionomer cement and/or composite resin; 3. seal cracks, when present, with a bonding agent or composite restorations; 4. select bleaching gels that have low tooth sensitivity rates, proven by clinical research; 5. pay attention to the fact that patients with a history of sensitivity should take special care – lower concentration bleaching agents and lower daily application regimens should be recommended; for example, 10% carbamide peroxide for 15 minutes; 6. choose carbamide peroxide based bleaching gels, both for at-home as well as for in-office application techniques; 7. reduce the time of application of bleaching agent; for example, apply for 20 minutes in the in-office session and/or reduce for 15-30 minutes of daily use in the tray; 8. apply bleaching on alternating days, both for the at-home and in the in-office technique sessions; and 9. associate tooth bleaching techniques, in-office and at-home.

It should be emphasized that although reducing the contact time of the gel on the tooth structure and the reduction of the concentration of the product prolong the time to complete the bleaching treatment, this strategy will enable the bleaching of more sensitive teeth.8 Several professionals report that patients who have bleached their teeth frequently complain about the appearance of cracks and stains. Literature on the subject shows that there are not any available agent or technique which would produce spots and/or cracks, which leads us to conclude that they already existed and only became visible.4 For this reason, we consider it essential to transilluminate the teeth before initiating the bleaching treatment and show the patient the possible existence of cracks and stains, as well as to advise them as to whether they become visible after bleaching. Another difficulty encountered in the protocol is to establish a minimum period for the bleaching treatment, considering the different color tones that natural teeth present and the different degrees of bleaching desired by each patient. Thus, the dentist should be able to tell the difference between a result they consider satisfactory and the result desired by the patient. This may involve the reduction of several days of treatment, even for patients with more yellowish teeth, or performing only one in-office session to meet patients who already have white teeth or that do not wish teeth so clear.Therefore, establishing a single treatment period, e.g., 30 days, may represent overtreatment for some patients, while a period of 15 days may be insufficient for other. Concerning the different color tones in the dental arch, it is noteworthy that darker teeth will require stronger action of the bleaching agent in contact with the tooth structure to equalize the shade with the brightest teeth of the arch. This may imply only bleaching the saturated teeth for a greater number of days or the association of in-office applications solely for these teeth in order to accelerate the bleaching treatment. 185

Another question of professionals is when to stop bleaching, especially when seeking very white teeth. Even though the literature considers the saturation point – when there is no dye molecules to be broken and the bleaching gel starts to degrade the organic matrix of dentin – as the limit for brightening the tooth structure clinically is impossible to be established.39 Thus, we believe that the limit for bleaching naturally discolored teeth or those darkened by age should be determined from the stabilization of the color of the tooth structure in the weekly return appointments for evaluation of bleaching, while the patient is still not satisfied with the result. As seen, any product which carbamide peroxide or hydrogen in its composition will promote bleaching of the tooth structure. Thus, the use of mouthrinses and toothpastes intended to be “bleaching” may be used as an aid in maintaining the achieved bleaching for at-home and/or in-office techniques. On its own, this type of product, if used for years, will also promote discoloration of the tooth structure,44 in the same way the use of whitening strips sold in drugstores and grocery stores are effective. However, any option, if unattended by the professional, will cause aesthetic damages, sometimes irreversible. Therefore, the best technique will be that which is surely indicated by the professional and that which meets the needs of the patient. Finally, another frequent question is concerning how long to wait before accomplishing the restorative procedures. As seen during the bleaching technique tooth dehydration in different intensities takes place, responsible for making teeth lighter than they actually are. Therefore, we recommend to wait the minimum length of seven days after finishing the bleaching treatment to accomplish the restorations, whether direct or indirect.35,43 In addition to tooth rehydration and stabilization of the color obtained, according to the literature this period is sufficient for any remaining oxygen is eliminated from the tooth structure,35 causing the adhesive bond strength values of the direct and indirect restorations not to be compromised, which will prolong the longevity of the restorative treatment. With the different bleaching techniques and the wide variety of commercially available products, it is possible to promote tooth bleaching with a minimal of side effects with different intervals of treatment, and it is even possible to bleach overly sensitive teeth. Unquestionably, our recommendation is using carbamide peroxide based products, since all clinical studies show them to be safer for bleaching. However, it is essential to know the mechanism of action of products available and how they should best be managed to achieve the desired results in different clinical situations. The case presented in the photographs (Fig. 1-8) illustrates the clinical management performed in the care of a patient who aimed to bleach teeth and close the interdental spaces with ceramic veneers.

186

Figure 1a.

Figure 1b.

Figure 1c.

Figure 1d.

Figure 1a-d.Facial photographs with the initial appearance of a 25 year-old male patient, who sought care aiming to to have white teeth without interdental spaces.. Photographs taken by Dudu Medeiros.

187

Figure 2a.

Figure 2b.

Figure 2c.

Figure 3a.

Figure 3b.

Figure 4a.

Figure 4b.

Figure 5a.

Figure 5b.

Figures 2a-c. The photos of fa orced smile is observed in addition to the disharmony of the color of teeth involved in the aesthetics of the smile, a significant discrepancy in the length of canine teeth due to gingival recession. Figures 3a-b. Intraoral photographs taken 180 days postoperative follow-up in the region of 13 submitted to the subepithelial connective tissue graft technique for correction of gingival recession, and clinical crown lenghtening on teeth 11 and 12, which greatly compromised the smile aesthetics (see Chapter 5.2). Figures 4a-b. As indirect veneers would be carried out to restore the dental proportions closing the existing diastemata and the color of the indirect restorations would be determined considering the color of the natural teeth, they would not be involved in the restorative treatment, it was essential to initiate the tooth bleaching treatment. As posterior teeth were darker than the anteriors and the patient did not exhibit sensitive teeth, it was decided to associate both the home and the in-office bleaching techniques in order to reduce the treatment time. With the help of the shade guide (Vita Classical®, Vita, Germany) it was possible to observe the degree of tooth darkening, highlighting the most saturated color of the posterior teeth. These photographs were also required to record the initial color of the teeth before initiating the bleaching treatment, for use for future reviews. Figures 5a-b. Bleaching was carried out for 16 days by the at-home technique, using a 16% carbamide peroxide product (BM4, Florianópolis, Brazil) for 2 hours daily, associated with three daily applications of in-office 37% carbamide peroxide (BM4, Florianópolis, Brazil)for 45 minutes, on all of the teeth. After 4 days of the last clinical session, it was observed that only the posteriors were unsatisfactory color. Three additional daily clinical applications were repeated, from the canines to the posteriors, concurrently with the daily use of 16% carbamide peroxide to enhance the results. After 10 days of treatment with the aid of the shade guide (Vita Classical®, Vita, Germany), the color change achieved with the combined bleaching techniques may be observed.

188

Figure 6a.

Figure 6b.

Figure 6c.

Figure 6d.

Figure 6e.

Figure 6f.

Figure 7.

Figures 6a-f. Satisfactory result desired by the patient, after 10 days of tooth bleaching. No symptoms of sensitivity were reported during treatment. As completion of treatment would be with indirect veneers, seven days were expected for tooth rehydration and stabilization of the final color obtained. After this period, the remaining oxygen in the tooth structure would have been released and restorative procedures could be accomplished without compromising the strength values of the adhesive bond. Final laboratory aspect of the ceramic restorations (a) and after cementation of the veneers (12-22) and fragments (13 and 23), made from feldspathic ceramic (b). In the interocclusal photo (c) it is observed that the new dental proportions are properly adjusted to the patient’s occlusion. In the smile (d) the harmony achieved from the correction of the gingival zenith and new proportions (length and width) of the anterior teeth can be observed. Finally, pictures with the shade guide (Vita Classical®, Vita, Germany) demonstrate the success of the association of the ceramic veneers and bleaching techniques, having obtained an aesthetic resulting from a conservative approach, due to the elimination of the need to carry out tooth preparation to offer greater volume for the application of the ceramic and masking the color of the substrate (e-f). Figures 7 and 8. Harmony in the rehabilitation assembly with ceramic veneers and the result optimized by the the bleaching technique carried out. Photographs taken by Dudu Medeiros.

189

Figure 8.

190

191

2. Azer SS, Rosenstiel SF, Seghi RR, Johnston WM. Effect of substrate shades on the color of ceramic laminate veneers. J Prosthet Dent. 2011;106(3):179-83. 3. Baratieri LN, et al. Clareamento de dentes. In: Baratieri LN. Odontologia restauradora: fundamentos e possibilidades. São Paulo: Santos; 2001. p. 675-722. 4. Baratieri LN, Maia E, De Andrada MAC, Araújo E. Caderno de dentística: clareamento dental. São Paulo: Santos; 2003 5. Bernardon JK, Baratieri LN. Clareamento de dentes vitais. In: Barateiri et al. Soluções clínicas: fundamentos e técnicas. Florinópolis: Ponto; 2010. p. 89-107. 6. Bernardon JK, Ferrari P, Vieira LCC, Maia HP. Avaliação do tempo de tratamento para a satisfação do paciente nas diferentes técnicas de clareamento. In: 27ª Reunião Anual da SBPqO, 2010, Águas de Lindóia - SP. Brazilian Oral Research; 2010. p. 271. 7. Bernardon JK, Sartori N, Ballarin A, Perdigão J, Barateri LN. Clinical performance of vital bleaching techniques. Oper Dent. 2010;35:3-10. 8. Cardoso PC, Reis A, Loguercio A, Vieira LC, Baratieri LN. Clinical effectiveness and tooth sensitivity associated with different bleaching times for a 10 percent carbamide peroxide gel. J Am Dent Assoc. 2010;141(10):1213-20. 9. Carvalho LD, Brusi G, Bernardon JK, Baratieri LN. Cabamide peroxide vs hidrogen peroxide in-office bleaching: efficacy, treatment time and post-operative sensitivity. Oper Dent. 2014, no prelo. 10. Costa CAS, Huck C. Cytotoxic effects and biocompatibility of bleaching agents used in dentistry: a literature review. Robrac. 2006;15(39):3-14. 11. Costa CAS, Riel H, Kina JF, Sacono NT, Hebling J. Human pulp responses to in-office tooth bleaching. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2010;109(4): 59-64. 12. Cunha-Cruz J, Stout JR, Heaton LJ, Wataha JC. Dentin hypersensitivity and oxalates: a systematic review. J Dent Res. 2011;90(3):304-10. 13. Deliperi S, Bardwell DN, Papathanasiou A. Clinical evaluation of a combined in-office and take-home bleaching system. J Am Dent Assoc. 2004;135(5):628-34. 14. Elfallah HM, Swain MV. A review of the effect of vital teeth bleaching on the mechanical properties of tooth enamel. N Z Dent J. 2013;109(3):87-96. 15. Fasanaro TS. Bleaching teeth: history, chemicals, and methods used for common tooth discolorations. J Esthet Dent. 1992;4(3):71-8. 16. Gallo JR, Burgess JO, Ripps AH, Bell MJ, Mercante DE, Davidson JM. Evaluation of 30% carbamide peroxide at-home bleaching gels with and without potassium nitrate: a pilot study. Quintessence Int. 2009;40(4):1-6. 17. Gottardi SM, Brackett MG, Haywood VB. Number of in-office lightactivated bleaching treatments needed to achieve patient satisfaction. Quintessence Int. 2006;37(2):115-24. 18. Hatwwod, VB, Heymann HO. Nightguard vital bleaching. Quintessence Int. 1989;20(3):173-6. 19. Haywood VB, Leonard RH, Nelson CF, Brunson WD. Effectiveness, side effects and long-term status of nightguard vital bleaching. J Am Dent Assoc.1994;125(9):1219-26. 20. Joiner A. The bleaching of teeth: a review of the literature. J Dent. 2006; 34:412-9. 21. Jorgensen, MG, Carroll WB. Incidence of tooth sensitivity after home whitening treatment. J Am Dent Assoc. 2002;23:107682. 22. Kawamoto K, Tsujimoto Y. Effect of the hydroxyl radical and hydrogen peroxide on tooth bleaching. J Endod. 2004;30(1):4550. 23. Kina JF, Huck C, Riehl H, Martinez TC, Sacono NT, Ribeiro APD, Costa CAS. Response of human pulps after professionally applied vital tooth bleaching. Int Endod J. 2010;43;572-80. 24. Kwon SR. Whitening the single discolored tooth. Dent Clin North Am. 2011;55(2):229-39. 25. Kwon SR, Wang J, Oyoyo U, Li Y. Evaluation of bleaching efficacy and erosion potential of four different over-the-counter bleaching products. Am J Dent. 2013;26(6):356-60. 26. La Penã AV, Cabrita B. Comparison of the clinical efficacy and safety of carbamide peroxide and hydrogen peroxide in at-home bleaching gels. Quintessence Int. 2006;37(7):551-6. 27. Leonard RH Jr, Haywood VB, Eagle JC, Garland GE, Caplan DJ, Matthews KP, et al. Nightguard vital bleaching of tetracycline-stained teeth: 54 months post treatment. J Esthet Dent. 1999;11(5):265-77. 28. Leonard Jr H, Bentley C, Eagle JC, Garland GE, Knight MC, Phillips C. Nightguard vital bleaching: a long-term study on efficacy, shade retention, side effects, and patients’ perceptions. J Esthet Restor Dent. 2001;13(6):357-69. 29. Leonard RH Jr, Haywood VB, Caplan DJ, Tart ND. Nightguard vital bleaching of tetracycline-stained teeth: 90 months post treatment. J Esthet Restor Dent. 2003;15(3):142-52. 30. Marson FC, Sensi LG, Araujo FO, Monteiro-Junior S, Araújo E. Avaliação clínica do clareamento dental pela técnica caseira. Rev Dental Press de Est. 2005;2(4):84-90. 31. Matis BA, Gaiao U, Blackman D, Schultz FA, Eckert GJ. In vivo degradation of bleaching gel used in whitening teeth. JADA. 1999;130(2):227-35. 32. Matis BA, Yousef M, Cochran MA, Eckert GJ. Degradations of nine bleaching gels after two hours in vivo. Oper Dent. 2002;27(1):12-8. 33. Matis BA, Cochran MA, Franco M, Al-Ammar W, Eckert GJ, Stropes M. Eight in-office tooth whitening systems evaluated in vivo: a pilot study. Oper Dent. 2007;32(4):322-7. 34. Meireles SS, Heckmann SS, Leida FL, dos Santos Ida S, Della Bona A, Demarco FF. Efficacy and safety of 10% and 16% carbamide peroxide tooth-whitening gels: a randomized clinical trial. Oper Dent. 2008;33(6):606-12. 35. Miranda TA, Moura SK, Amorim VH, Terada RS, Pascotto RC. Influence of exposure time to saliva and antioxidant treatment on bond strength to enamel after tooth bleaching: an in situ study. J Appl Oral Sci. 2013;21(6):567-74.

192

REFERENCES

1. Al-Qunaian TA, Matis BA, Cochran MA. In vivo kinetics of bleaching gel with three-percent hydrogen peroxide within the first hour. Oper Dent. 2003;28(3):236-41.

36. Moghadam FV, Majidinia S, Chasteen J, Ghavamnasiri M. The degree of color change, rebound effect and sensitivity of bleached teeth associated with at-home and power bleaching techniques: a randomized clinical trial. Eur J Dent. 2013;7(4):40511. 37. Navarra CO, Reda B, Diolosà M, Casula I, Di Lenarda R, Breschi L, Cadenaro M. The effects of two 10% carbamide peroxide nightguard bleaching agents, with and without desensitizer, on enamel and sensitivity: an in vivo study. Int J Dental Hygiene. 2014;12(2):115-20. 38. Pugh G Jr, Zaidel L, Lin N, Stranick M, Bagley D. High levels of hydrogen peroxide in overnight tooth-whitening formulas: effects on enamel and pulp. J Esthet Restor Dent. 2005;17(1):40-5. 39. Riehl H, et al. Clareamento de dentes vitais e não vitais: uma visão crítica. In: Fonseca AS. Odontologia estética: a arte da perfeição. São Paulo: Artes Médicas; 2008. p. 499-565. 40. Rosenthal MW. Historic review of the management of tooth hypersensitivity. Dent. Clin N Amer. 1990;34:403-27. 41. Sundfeld RH, Sundfeld-Neto D, Machado LS, Franco LM, Fagundes TC, Briso AL. Microabrasion in tooth enamel discoloration defects: three cases with long-term follow-ups. J Appl Oral Sci. 2014;22(4):347-54. 42. Trindade FZ, Ribeiro AP, Sacono NT, Oliveira CF, Lessa FC, Hebling J, et al. Trans-enamel and trans-dentinal cytotoxic effects of a 35% H2O2 bleaching gel on cultured odontoblast cell lines after consecutive applications. Int Endod. 2009;42(6):51624. 43. Torneck CD, Titley KC, Smith DC, Adibfar A. The influence of time of hydrogen peroxide exposure on the adhesion of composite resin to bleached bovine enamel. J Endod. 1990;16(3):123-8. 44. Torres CR, Perote LC, Gutierrez NC, Pucci CR, Borges AB. Efficacy of mouth rinses and toothpaste on tooth whitening. Oper Dent. 2013;38(1):57-62. 45. Watts A, Addy M. Tooth discoloration and staining: a review of the literature. J Br Dent. 2001;6:309-16.

193

chapter 5.4

occlusal plastic restorative therapy João Christovão Palmieri Filho

How to justify the vast number of relatively young patients seeking treatment for extensive dental destruction? (Fig. 1, 2 and 3) Not infrequently the main complaint of this group of individuals is concerning the poor appearance brought by that destruction. For a while, Dentistry came to believe that the strict oral microbiological control would be enough to prevent this from happening. However, these patients even in the face of low rates of decay or with few restored teeth, have wear or loss of coronary portions that justify the dental rehabilitation. In this way, professionals are facing an era when biomechanical, behavioral and environmental factors start to play an important role in the genesis of what has been called the occlusal disease.1 The occlusal disease was defined as the loss of anatomical portions of the teeth participating in the occlusion. Better explained, it is the loss of the original anatomical contour due to friction between the teeth, with or without interposition of abrasive agents or acidic substances. In this context, bruxism appeared as an event-disease and main causal agent of this type of wear, ie, the association between bruxism and occlusal disease has become practically unequivocal. However, there is evidence that bruxism is associated with stress relief.2 In this case, bruxism cannot be considered a disease; on the contrary, it should be considered a protective factor. This becomes clearer when it was observed that the genesis of this intense masticatory activity is located in the central nervous system (CNS).9 The teeth are at the end, not at the beginning of this chain of events. One would then question: the muscles that move the jaw and which generates work between teeth obeys a command center regardless of the stimuli that these teeth send to the CNS? The answer is not yet clear, but it is known that teeth are organs of physical and immunological modulation of a particular lifestyle. The lifestyle of the “modern human”. Therefore, the loss of part of alveolar bone structure due to biomechanical fatigue becomes associated with a factor outside the occlusal system. And Dentistry, out of its own desperation, has become responsible for a risk factor which is independent of teeth. To make an analogy, the quality of a vehicle is independent of the driver’s intentions. An unbalanced car in the hands of a calm and careful driver is less prone to accidents than a powerful and balanced car in the hands of a reckless, inconsequent driver. The driver, in this case, is the CNS. For the professionals who dedicate their lives to the rehabilitative dentistry, the possibilities of rebuilding and adjusting these occlusal systems remain in the most balanced manner as possible, from anatomical, neuromuscular and social point of view. And hope the “driver” to be prudent and observant.

196

Figure 1a.

Figure 2.

Figure 1b.

Figure 1c.

Figure 3.

Figure 4.

Figures 1-4. Frontal in maximal intercuspation and upper and lower occlusal photographs of a 28 year old patient presenting initial degree of coronary destruction attributed to parafunctional habits such as nocturnal bruxism. Severe cusp abrasion is observed. From canine to third molars, geometrically sharp portions of wear can be identified.These paths may be termed cuspal or crestal remaining bases. This concept will be of great value in the reconstruction of the original anatomical shape.

197

bilitation of the dental occlusion without necessarily having to reduce and destroy the tooth remnants. The possibility of veneering the crown of a tooth with pure fused or machined porcelain, bonded to the coronal structure by a thin layer of resin cement, has made this prosthetic assembly as much or more resistant than the original tooth,3 which has become the cornerstone of current dental rehabilitation. At this turning point from the old mechanical retention standards to the undeniable method of adhesive retention, this chapter addresses the principles, concepts and prac-

SOCIAL FUNCTIONS OF TEETH

The evolution of materials and techniques in Dentistry have made possible the reha-

tices of the classical occlusal rehabilitation which should remain and what is more prevail in this new era, predicted more than 50 years ago by Buonocore.4 If the basis of our current technology was born out of the work of the professionals for over five decades, one should bring to memory those works which have allowed us to get here. The idea of terminal axis established by final position of the heads of the mandible against the mandibular fossa with increased power of the lifting muscles (masseter, temporal and internal pterygoid) working free from dental contacts, is not new5 and it is fundamental to Dentistry to be applied, as well as the demonstration of the role played by the tooth contact (and by the absence of this contact as well) on this very musculature.6 Upon this basis, of a hundred of years, has described and demonstrated a means of restoring the occlusal balance, indispensably necessary for the durability of rehabilitations

In epidemiological terms, the aim of every rehabilitation is limiting the damage and recovering of the residual capacities. Its ideal is returning to the individual primary and secondary levels of prevention.7 Referring to the occlusal rehabilitation, one must keep in mind the recovery of the bite force, the masticatory ability, good appearance and the consequent social impact this represents. The rehabilitation of the patient’s occlusion is closely related to the overall health of the individual.8 Figure 1 helps to situate the concept of rehabilitation as a tertiary prevention. The dental practice, as a health science, can be readily framed into different levels of attention. For example, the instruction of oral hygiene to patients fits into the first level of the scale, primary prevention, as a health promotion measure. Still at the level of primary prevention, topical application of fluoride or even carrying out pit and fissure sealants are specific measures of protection. From the third to the fifth levesl, the focus is on working with the rehabilitation of health. From the point of view of occlusion, when the professional deals with an initial carious lesion, early diagnosis and proper treatment are performed. Accomplishing an endodontic treatment on this very tooth limits the damage and allows for the element to be restored to the occlusal function. When the entire set of teeth inexorably moves toward a collapse, the fifth level is reached: the occlusal rehabilitation.

198

OCCLUSAL REHABILITATION AS TERTIARY PREVENTION

and the comfort of the patients as well.

Quadro 1. Application levels of health measures and equivalence of terms used for designation. From Pereira, Maurício: Epidemiology Theory and Practice. Guanabara Koogan, 1995.

FIRST LEVEL

SECOND LEVEL

THIRD LEVEL

FOURTH LEVEL

FIFTH LEVEL

Health promotion .

Specific protection .

Early diagnosis and timely treatment

Limitation of the damage .

Rehabilitation .

Prevention

Prevention

Care

Care

Rehabilitation

Primary prevention

Primary prevention

Secondary prevention

Secondary prevention

Secondary prevention

Promotion

Protection

Recovery

Recovery

Recovery

Instruction oral hygiene/ nutritional counseling

Topical application of fluoride / sealants

Restoration/orthodontics/ orthognatics

Endodontics, implant, crowns, extensive restorations etc.

Tooth- and/or implant- or tissue-supported prostheses

It is pertinent to note that, as the treatment progresses along this scale of prevention, the level of expenditure rises. The amount to be spent on an occlusal rehabilitation may be hundreds of times higher than that of the value of a dental prophylaxis. Even within the therapeutic possibilities of Dentistry, an occlusal rehabilitation using composite resin or ceramic veneers tend to be more economical than the equivalent job that uses osseointegrated implants and porcelain crowns. And not only from a financial perspective, but

THE STARTING POINT FOR AN OCCLUSAL REHABILITATION

especially from a biological sense.

Each and every treatment should be preceded by the proper diagnosis. This clinical truth is often set aside when it comes to rehabilitation of the occlusion. Treating a diseased occlusion without identifying, qualifying and quantifying the disease is akin to merely performing palliative procedures and running the risk of making temporary crowns as definitive restorations. The diagnosis of the occlusal disease indicates that it should analyze the amount and frequency of parafunction or hyperfunction performed by the patient. The higher the degree of occlusal imbalance and the greater the level of parafunction, the greater the destruction of the tooth.1 The occlusal diagnosis can not be performed through the mere observation of the coronary destruction. The alveolar bone, periodontal ligament, joints, muscles, and especially the neuromuscular coordination should receive attention during the formulation of the hypotheses about how, when and why a system that should function without damage could progress towards its collapse.

199

ten, seems to overcome destruction generated by microbiological factors. Considering that this type of destruction takes place over several years and requires time to become evident, the early diagnosis allows for a less invasive intervention and more predictable results, equally in terms of aesthetics as well as the longevity of the treatment. In Figure 4, from the picture of the smile it is possible to infer the following considerations: 1. reduction of incisal edges and cusp tips took place, principally of the canine teeth; and 2. there is a swelling on the left side of the lower lip, which could have been caused by recurrent unconscious trauma (morsicatio labiorum). Starting from these two considerations, it is interesting to ask the individual about habits and manias. Normally, the answer obtained that both the grinding of teeth such

IDENTIFYING THE OCCLUSAL DISEASE BY THE SMILE

As stated earlier in this chapter, dental destruction by biomechanical factors, of-

as repetitive lip biting, if it really occurs, happen overnight or unconsciously. Also not infrequently, in subsequent appointments, the patient reports situations where a repetitive habit has been properly noticed (Fig. 5). Eventually, there may be a report by the family or friends concerning sounds of tooth grinding during sleep. If this is enough to confirm a classic case of sleep bruxism,9 it is up to the professional to explain what the relationship is between bruxism and stress relief.2

Figure 5.

Figure 6.

Figure 5. Questioned and instigated to produce a repetitive and unconscious habit, the individual is able to reveal to the professional, and often himself, situations comparable to self-flagellation. Figure 6. When evaluating the degree of coronary destruction one should consider the age of the individual. In the case described in this chapter, the patient is young (28 years), so the loss of the cusp tips of the canine and incisal edges and “peeling” of the resin in the cervical region of the first premolar indicates severe attrition and overloading, some abrasion by toothpaste abuse and a little erosion of coronary surfaces.

200

BEYOND ATTRITION, EROSION AND ABRASION

Tooth wear is a process with a multifactorial cause that leads to the loss of enamel and dentin as well as pulp sclerosis. This loss of substance can occur by dental attrition of a tooth against a tooth by acid erosion or abrasion by external agents, as in cases of excessive dentifrices or abrasive food.10,11 It is noteworthy that, in practice, rarely is there a single factor that acts in the loss of tooth substance. Loss due to attrition can be diagnosed by the polished appearance of opposing tooth surfaces, as well as by the perfect fit of the forms of wear between antagonist teeth. In severe cases, there is also some masseter hypertrophy, by a noteable scalloped appearance of the edges of the tongue and report of repeated mucosal lesions. Both enamel and dentin will dissolve in an acidic environment. The origin of this acidifying agent can be both extrinsic (juices, soft drinks or medicines) and intrinsic (stomach acid from reflux). In extremely low pH conditions with the oral cavity, the attrition of the tongue becomes an adjunctive agent of erosion. Therefore, there is characteristic wear on the palatal surfaces of the anterior and internal cusps of the posterior. Toothpaste abuse is an abrasive factor that cannot be overlooked. It is believed that, because it is a product for daily use, it is capable of removing tooth substance if used in excess. And the damage may be aided by the phenomenon of abfraction.12 The importance of identifying different patterns of loss of tooth structure lies in the accuracy of the diagnosis. For example, measures of occlusal reconstruction and the use of bite splint may be sufficient for rehabilitative treatment, However, in the case of a patient with a severe gastric reflux, additional control measures should be taken. At that moment the accuracy of diagnosis will easily convince the patient to seek help from an expert. In addition, the dentist stops being merely a mouth mechanic and behaves like a

THE OCCLUSAL DISEASE

health professional.

Initially described as a process resulting from noticeable loss of structure and destruction of the coronary surfaces of the teeth, the concept of an occlusal disease has evolved to include any change that results from overloading and imbalances in the occlusal system.13 Thus, one must expand the analysis and move beyond the restorative view of the tooth and periodontium. Manifestations of the occlusal disease occur throughout the system: the temporomandibular joints (TMJ), the muscles, the degree of bone condensation or rarefication and even the perception of “bite comfort” felt and reported by the patient.

201

maxilla and the mandible, temporomandibular joints, the muscles involved in the mobility of the jaw, facial movement and tongue, and, of course, the relevant neural pathways that act, react and especially coordinate movements. Therefore, the occlusal diagnosis will evaluate each of these components. Although the occlusal rehabilitation basically deals with the modification and recovery of the shape of the teeth, a proper diagnosis will allow refering patients to other specialties. It is always a valid warning that even an ideal treatment, a misdiagnosis is a potentially a misguided treatment. It is possible to start with articular evaluation. This chapter does not describe the pathophysiology of the TMJ, however starting an oral therapy regardless of the state of this important component is a risk we should avoid. Although there is quite sophisticated equipment for the evaluation of joint vibrations as well as advanced diagnostic imaging,14 are considered here is merely an appreciation of mobility, production of noise and the presence of joint pain as part of the obligatory initial evaluations. It is recommended for further study reading the book of Professor Anika Isberg Temporomandibular Joint Dysfunction, a guide for the clinician. Despite the years since its publication, this work seems to be very didactic and easy to assimilate by the rehabilitating clinician. Ask the patient to open and close the mouth allowing the professional to place the index and middle fingers to anatomically identify the heads of the mandible (condyles) as well as to locate the right and left joints (Fig. 7a). In this region, we can palpate with force equivalent to 1 or 2 kg searching for sensitivity. These areas are basically from the capsule or even from the temporomandibular ligament, when palpating the lateral condylar aspect towards the temporal region. With the mouth wide open, the index finger is placed in the distal condylar pole, it is possible to palpate the retro-disc region (Fig. 7b). This maneuver should be performed with care and gentleness. Since this is a richly innervated and vascularized region, there is risk of sharp surging pain, most importantly not begin any palpation by applying a 2 kg force. One can start with a tenth of that. This observation serves for the whole examination. Some patients have acute pain after a simple light rubbing of the finger. Continuing the examination, one can explore the masseter (Fig. 7c) the temporal (Fig. 7d) and the lateral pterygoid muscles (Fig. 7e). The result of these examinations can be classified as: painless, mild, moderate or severe pain. Remember that the pain is pathognomonic of inflammation, parameter that can also be used during muscle palpation. Articular changes are not rarely accompanied by muscle disorders. Therefore, it is necessary to identify clinically the weight of each component in the generation of dysfunction in the system. This is because it is believed that intra-articular pathologies are not likely to heal through the occlusal rehabilitation. At best, the treatment will allow for a functional adaptation, an inflammatory remission or stabilization of the degenerative picture. On the other hand, in the predominantly muscular disorders, the balance of occlusion will generate very positive responses in the reports of our patients. From the electromyographic point of view, this better performance will translate into lower electric potentials at rest and better coordination of movements.15 Electromyography is 202

THE OCCLUSAL DIAGNOSTICS

The occlusal system (OS) comprises the set of teeth and the periodontium, the

not routinely indicated for diagnostics. However, it is quite enlightening to show how the masseter and anterior bundle of temporal muscles behave, in cases of occlusal imbalance and how it is possible to manipulate these electric potentials by changing only and uniquely the dental contacts.

Figure 7a.

Figure 7b.

Figure 7c.

Figure 7d.

Figure 7e.

Figure 8.

Figures 7a-e. The survey of muscle palpation seeks to identify points of rigidity and pain in muscles and ligaments. It is a test that can be accomplished in less than 3 minutes and will certainly enhance the diagnosis. Figure 8. The patient underwent electromyography of masseter and anterior temporalis. Despite the possibility of identifying changed electrical patterns for both resting and maximum bite positions and lateral movements, such information should be accounted for with those other collected during our occlusal examination.

203

(TRA), in a semiadjustable articulator, is a mandatory step for proper occlusal diagnosis. All of the registrations - maxillary and mandibular study impressions, auricular facial bow, resin or impression compound anterior jig, and wax or elastomer interocclusal registrations – are procedures that with a little practice can be performed in less than 30 minutes. Semiadjustable (A7 Plus®, BioArt, Brazil) or mean value (A7 Fix®, BioArt, Brasil) articulators are inexpensive and very reliabile equipment. With this information, one wonders: why too few professionals lay hold of an occlusal diagnosis in TRA? If the time spent in obtaining the information is less than the expenses to make a simple repair on a restoration that insists on fracturing and the equipment used is less costly than a newly installed porcelain crown which has already fractured, a reasonable explanation for the giving up of the occlusal diagnosis thereby is simply not knowing how to use an articulator. The so-called central relationship (CR) is a reference position between the mandible and maxilla. When both heads of the jaw reach that position, they establish a virtual axis which we call the terminal rotation axis or terminal hinge axis (TRA or THA). It is in the condylar position of maximum intrusion when the lifting muscles are triggered without the interference of the teeth, the individual can achieve TRA in working CR. There are some tricks for recording that position. Both the bidigital manipulation technique indicated by Peter Dawson16 as well as the anterior jig technique by Victor Lucia17 are found to be successful and easily reproducible. The technique used in the case-example of this chapter is a variation of the Lucia’s JIG, called “jig and pin” (JP), because provides for simultaneous preparation of an acrylic plane attached to the maxilla and a pin between the mandibular central incisors (Fig. 9a-b). With the possibility of free movement on the horizontal plane, without dental contact to trigger defensive positions against prematurities, tracing will indicate the border limits on the most relevant plane of the movement of the jaw, at least as regards occlusion. If one reminds the study by Ulf Posselt,18 it is on the horizontal plane that teeth will touch and work. Knowing that the simple rustling of the teeth works as an activator or interrupter of muscle activity,19 the free registration of myoneural reaction postures other than the mandibular elevation allows us to find an easily reproducible starting axis. When the JP device has been installed on the dental arches, one can ask the patient to repeatedly occlude. The initial contact may be wandering. However, with repetition of the movement there is a tendency to generate a single point of contact. At this point, one can interpose a carbon tape and graphically mark the spot (Fig. 10). The right and left movements of lateralization, and the protrusive mandibular movement, can be recorded. One can use different color-coded carbon tape to differentiate movements with and without manipulation. The degree of coordination and range of motion can in this manner be merely evaluated through plotting (Fig. 11).

204

WHY TO SEARCH FOR A TERMINAL AXIS OF ROTATION?

The obtaining of study models mounted on a terminal rotation axis of the mandible

Figure 9a.

Figure 9b.

Figure10.

Figure11.

Figures 9a-b. Manufactured in self-curing acrylic, with the help of an ovoid glass plate, to make the incisal plane in the maxilla, and the help of the fingers, for fabricating a pyramidal pin between the lower central incisors, the jig and pin allow for to outline the limits of the mandibular movements in the horizontal plane, with the interposition of a tape or occlusal contact marking film. Figure 10.The central point is marking the point of coincidence of three unguided consecutive contacts, recorded with an interposed carbon tape. This may or may not be the posterior hinge of the mandibular movement. Often, it is possible to manipulate the jaw so as to obtain a more distal position, that when forced may be recorded graphically, but not necessarily serve to establish the maxillomandibular relationship of the work.

RECORDING THE WORK RELATIONSHIP BETWEEN MAXILLA AND MANDIBLE

Figure 11. From this point, the lateral movements occur without hesitation or mishaps. The same may not be inferred from the protrusive movement. The tracings generated by three consecutive records are shown as oscillatory (blue arrow).

Considering that the condylar position of maximal muscle elevation may be an ideal position for determining the highest number of simultaneous occlusal contacts, it should kept in mind that not always the occlusal registration results in obtaining this position. At this moment, auxiliary techniques such as the bimanual manipulation of Dawson and CT images appear to increase the degree of registration accuracy. The option of using double # 9 wax rolls for recording the maxillomandibular relationship, as advocated more than 40 years ago by Arne Lauritzen,5 is due to the simplicity and high effectiveness of the technique (Fig. 12). Using the jig and post, even considering that the position of the greatest retrusion condylar is graphically obtained when the patient is instructed to occlude with the interposed wax, it is expected that the lifting muscles or the strength of bimanual manipulation, is capable of bringing the heads of the jaw to the highest possible position, in which the greatest number of occlusal contacts should occur.

205

Figure 12.

SAGITAL VIEW - RIGHT SIDE

SAGITAL VIEW - LEFT VIEW

Figure 13a.

SAGITAL VIEW - RIGHT SIDE

SAGITAL VIEW - LEFT VIEW

Figure 13b.

Figure 12. Registration with the pin touching the jig in the distal vertex of the marking. The lifting muscles of the patient or Dawson manipulation allow to position the mandible heads more superiorly. Things that must be clear: the result of this record will not necessarily be used to find the maximal intercuspation. The depicted position is, first of all, an orthopedic position. Figure 13a. On examination with the jig and interposed pin and patient activating the lifting muscles, it can be seen the intrusion of both heads of the jaw towards the fossa roof, even with the interincisal clearance. This position, once transferred to an articulator, allow the verification of initial tooth contacts and deflections that the jaw will make in pursuit of a larger number of occlusal contacts in maximum intercuspation. Figure 13b. On examination with the patient in maximal intercuspation, we see both a more anterior and lower position of both heads of the jaw. Imagining that the space interincisal decreased while the increased intra-articular space, one should consider that there was a mandibular torque around a dental posterior fulcrum. Understanding this phenomenon is of paramount importance to the findings in the semi-adjustable articulator.

206

The patient model in this case seems to be very illustrative: it is possible to clearly identify the habitual closing position that is not easy to be “deprogrammed” and a more distal position (Fig. 11). So the question arises: which of the two points should we consider for repositioning the maximal occlusion? In this situation a CT in TRA and maximum intercuspation positions may be valid. Any excessively posterior position would imply retrodiscal tissue compression, which should be avoided. Considering the espherographic registration occurs with pantographic bows or digitally, there is very important information for correctly diagnosing the mandibular mechanics. However, this chapter is addressed to a group of professionals who essentially do not believe that the use of a simple semiadjustable articulator is relevant to rehabilitate a smile. It is not recommended to use CT scans to verify the joint position resulting from the registration with the jig or bimanual manipulation. However, for illustrative purposes, the model patient was submitted to two different CTs: one at maximal

REGISTRATION OF THE CRANIOMANDIBULAR RELATION

intercuspation; and another with the jig and drill interposed (Fig. 13 a-b).

The relevance of using the face bow to register the correct positioning of the maxilla relative to the skull may be questioned. Once again it is worth questioning: if to apply an ear facial bow and obtain a very effective cephalometric registration takes less than one minute, what is the merit of not using it? The care to be taken is in rightly aligning the facial bow,  in relation to the skull and face of the patient. This alignment should be routinely verified along the three following planes: frontal, sagital and coronal (Fig. 14a , 15 b-c). It is a source of error to make this type of registration the fake laying of the intra-ear olive and the nasion rod (N).

Figure 14a.

Figure 14b.

Figure 14c.

Figure 14a. In the frontal plane, the facial bow must pass parallel to the imaginary line that would unite both orbital points (Or). It is common in this type of instrument that the N point is marked in a standard height bar. In cases of too much dolicocephalic or brachycephalous patients, we can ignore the nasion stem and place the arc in relation to the line Or-Or. Figure 14b. In the sagittal plane, the positioning of the intraaural olive is the closest support of Porion point (Po). Thus, bilaterally guided by Po and Or points, the facial bow would approximate the Frankfurt plane. Figure 14c. In the horizontal plane, it should be noted the centralization of the bow. The intercondylar distance measurement is optional. When we are dealing with the rehabilitation planning in wax, there will be the opportunity to better explain the option of using the average values for both intercondylar distance and the Bennett angle.

207

During the analysis of a pair of stone models mounted in an articulator, if the maxillomandibular registration and the assembly itself were carried out correctly, the first contact or couple of contacts in TRA should be easily found. Once the locks of that position are released, one must also find the position of maximal intercuspation (MI). Where it is impossible to establish MI, two situations may have occurred: either the individual moves the jaw distally to quit TRA towards MI,20 hich usually occurs with patients presenting Angle Class II division 2; or the mounting is incorrect. Anyway, in these cases making a new registration and reassembly of the models are valid. After the verification of the accuracy of registration and the mounting of the models, the occlusal analysis in the articulator is initiated. With the condylar latches activated, the upper hive is closed on the base, and the first occlusal contacts are looked for. Typically, these initial contacts occur on the last teeth of the arches: third, second or first molars. Often one side will show contacts before the other. When there is this type of situation, one may ask the patient which side they prefer while chewing. Unsurprisingly, the patient

ANALYZING THE MODELS MOUNTED IN THE ARTICULATOR

THE FIRST CONTACT

reports that it is the first contact side. The patient model illustrates very well this type of situation (Fig. 15a-b).

Figure 15a.

Figure 15b.

Figure 15a. The record with jig, pin and wax rolls allowed to establish an axis of rotation, to be transferred to the articulator, defined a closure arc, and consequently, the first occlusal contact. This is a possible biomechanical position and, more than that, a likely position. Analysis of wear facets generated by this first contact, on models and straight in the mouth, is enough. Figure 15b. On the contralateral side until the initial touch, the teeth fluctuated. In mouth, the absence of contacts on the right side will trigger a mechanism of neuromuscular adaptation. In fractions of a second, the mandible will move forward and bend in pursuit of tooth stability. This reflex, yet little studied, will affect the muscles, ligaments, teeth and the coordination of movements; not only of the mouth but in the whole body movements.21

208

THE OCCLUSAL LEVERAGE Figure 16a.

Once the first occlusal contacts in the terminal axis of rotation is detected, one should unlock the condyles of the articulator (if the equipment enable this feature)and observe the mandibular path until the greatest number of occlusal contact is achieved. The greater the distance to be covered, the greater the joint rocking and, consequently, the greater are the deleterious levers to the system. Using the case-patient model one can illustrate this kind of occurrence (Fig. 16a-b).

Figure 16b.

Figure 16a. The first contact with the jaw by rotating the terminal shaft occurred between the third left molars, which led to an anterior open bite.

THE VERTICAL DIMENSION OF OCCLUSION (VDO)

Figure 16b. Once released the condylar locks and the maximum interdigitation is achieved, it was observed that the bite opening moved to the joint region. This true occlusal teeter is the “exercise” unconscious which the individual performs, whether awake or asleep, and that present a risk to the system in that it allows the changing patterns of levers and destructive overloads.

In cases of severe coronary destruction by attrition, much is said about the loss of the vertical dimension of occlusion. However, by knowing the compensation mechanisms of wear by tooth eruption,22 it can be concluded that the “dimension which determines the OVD is located in the elevatory muscles and their repetitive length of mandibular closure”.23 However, the occurrence of the occlusal rocking described above allows for a discussion: the occurrence of a rocking that will switch the distance between the anterior teeth and the spacing between the condyle head and the mandibular fossa, with the dental posterior region as a fulcrum point or area and without necessarily changing the length of the elevator muscles, the concern with the vertical dimension of occlusion, with the articular and muscular vertical dimension that is required. This reflection will be very important when formulating an occlusal rehabilitation project, where the main objectives are the reduction of the articular gap and obtaining room for the anatomical rebuilding of the dental crowns, with the remaining the length of the lifting muscles of the jaw virtually unchanged. 209

at maximum intercuspation, the analysis of the protrusive and lateral movements are left. In this analysis, a relevant variable is the slope of the condylar guidance. Of the possible individualization in a semiadjustable articulator, this is which has the mostl potential of influencing the disocclusion of the posterior teeth. Therefore, it is recommended that in some cases it is checked. Some techniques for recording and transporting these figures to the articulator include an occlusal registration with wax or silicone while the mandible is in eccentric positions, the evaluation of images as panoramic radiographs or CT scans and also a simple direct measurement, in the patient’s mouth, of the degree of disocclusion generated in border movements and the production of wear facets.24 As shown by Williamson,19 the absence of posterior contacts in protrusive and lateral movements may relax the lifting muscles of the mandible. Then, the presence of these contacts during the excursive movements may not only increase muscle activity but can also modify the type of leverage generated by the system. It is noted that in cases such as that shown the fact of having a side that shows a contact before the other during the terminal rotation axis is enough for the appearance of a class I lever system, similar to a crowbar in the frontal plane (Fig. 17a-b). A similar phenomenon occurs when there is posterior contact in the balancing side during the lateral movements. The closing action on the working side and the presence of a posterior fulcrum allow the first type lever to appear as well as in the sagittal plane.

Figure 17a.

THE LATERAL AND PROTRUSIVE MOVEMENTS AND PRODUCTION OF LEVERS

After the verification of the contacts of the terminal axis of rotation and the contacts

Figure 17b.

Figure 17a. During the mandibular closure in the terminal rotation axis, the first contact  between the last molars on the left side starts to function as a fulcrum point. With the continuing movement, until the teeth touch on the right side, a type I lever system is generated and the work applied to the left articulation (Figure 17b. Orange arrow).

210

THE FINDINGS OF AN OCCLUSAL DIAGNOSIS

As stated earlier, the occlusal diagnosis is the result of the analysis of the state of the teeth and the periodontium, evaluation of the state of muscle hyperactivity, the state of articulation commitment and biomechanical possibilities of the system. Only after consideration of these variables is that you can offer some form of therapy. In the example shown, prior to the formulation of any treatment plan, the dentist should know what is being treated. In this situation, tooth wear occurs, pain triggering points upon palpation of both masseter muscles as well as in the anterior temporal and pterygoid muscles, signs of fatigue and hyperexcitation in the electromyography, signs of anatomical changes in the joints, without forgetting the main complaint of the patient, “my smile is bending”. That is symptoms occur! In this case, as in other cases with patients seeking treatment with complaints of an aesthetic nature, symptoms of pain, if any, are placed in the background, but the occlusal diagnosis needs to go beyond the appearance of the smile. It is necessary to identify the causes of the imbalance and the deterioration of the system, and thus propose therapies and prognosis. The presence of occlusal rocking described in the patient model may play a role in the imbalance of crown destruction process. What is worse, upon reaching the maximum intercuspation, there would be little or no disocclusion generated in the shear movements, ie the musculature is unable to be deactivated due to the absence of contacts. However, it must be clear that this imbalance is not the only or the major risk factor of alveolar bone destruction. If it was possible to attribute any priority to the genesis of this pathology, there would be the need to also look at microbiological, neurological, psychological, behavioral, and yet social factors. In the case of this patient, there are biomechanical, aesthetic, tender and degenerative signs indicating the need for intervention. Remember if there is the appearance is the only reference value, after the treatment completed there is the risk of facing, further complications, which may compromise the aesthetic result. The same applies to the isolated treatment of each of the above factors. A treatment that focuses solely on the biomechanics can not neglect the final appearance of the work. The elimination of pain will not necessarily stop the degenerative progress. A comprehensive diagnosis will reduce the risk of specific and ineffective treatments. Now there is a question: can the occlusal balance reduce the risk of the progression of the alveolar bone destruction? This is an issue undoubtedly not answered. The scarcity and difficulty of performing analytical longitudinal studies on the subject, there exists little evidence that occlusal rehabilitation is sufficient enough to stop the degeneration process of the system. However, a sectional cohort study with a population of patients with periodontal disease, with and without discrepancies along with occlusal adjustments after the occlusion, with a 15-year follow-up have indicated a clear relationship between the occlusal mismatch and the progression of periodontal disease.25 However, with an eminently clinical view, it can be said that an occlusal rehabilitation which provides balanced and simultaneous contacts, without or with a minimal articular offset during the maximum bite, and without contacts on the posterior teeth during lateral and protrusive jaw movements is capable of increasing the patient’s occlusal comfort. 211

There are means of measuring this increase in comfort. Contact sensors associated with electromiographs are able to quantify the occlusal contacts while the muscle behavior (masseter and anterior temporal bundle) is tracked.25 The occlusal diagnosis carried out from stone models mounted in articulator along with the terminal rotation axis relationship identify the degree of mandibular rocking, as well as the degree of disocclusion generated during the excursive movements of the mandible. This diagnosis should be the starting point for any rehabilitation proposal. For reasons of neuromuscular programming, via dental proprioception, disocclusion in rehabilitation should be generated. For generating disocclusion is necessary to establish the vertical overlapping (overbite) as well as inclined planes that do not inhibit sliding of the teeth. For a biomechanical matter, one should position the dental contacts and consequently the mandible so that the first and second type levers are eliminated or at least mitigated and, once said alignment has been achieved, it is possible to equally distribute

After reproducing the orthopedic relation of the mandible to the maxilla in the articulator, one should seek the alignment of the teeth. Clinically, it is possible to achieve balance and harmony in this alignment through movements, wear or by increments.27 When the professional encounters models in the articulator, it remains to trim the cast or add wax, to obtain the axial distribution of occlusal forces and disocclusion. Therefore, great importance is attributed to the occlusal diagnosis. Early identification of situations that can best be solved with orthodontic or even surgical movements, can save time, pain and money. Using the case of the patient, an occlusal reconstruction sequence in the articular simulator is demonstrated. For this purpose, the principle of sectorization by tooth quadrants is applied. The relationship between incisors and canines is restored, to establish later the most appropriate anatomy for the posterior teeth. The advantages of initiating the occlusal rehabilitation design through the establishment of an anterolateral guidance is to take advantage of the proper ratio of dental shapes and its consequent aesthetic predictability until the possibility of establishing slide paths absolutely harmonious with the articular displacement, without producing rocking nor mandibular leverages.

212

DESIGNING THE OCCLUSAL REHABILITATION

the dental contacts axially.

ALIGN THE MANDIBLE, THEN ALIGN THE CANINES…

By locating the terminal position in the right and left joints, the posterior axis is established. While the location of the contact between the maxillary and mandibular canines from both sides establishes a locking anterior axis. The idea is to obtain a chassis or a polygon where the remaining teeth will be positioned. Another issue that may already be solved with the alignment of the four canines is obtaining the vertical dimension of occlusion. For these solutions to be feasible, one should take hold of the principle of proportionality between the teeth. Starting with the use of the table of forms and size of the teeth28 it is possible to restablish dimensions of width to height for a posterior orientation (Fig. 18).

Cervicoincisal Root

M-D M-D neck

B-L

B-L neck Cervical M Cervical D Figure 18.

Figure 18. Table with average values in mm for the measurements of permanent teeth, the most important measures are the length and the mesiodistal diameter of the crowns. The values presented here were compiled from The Atlas of Permanent Teeth Anatomy (Fioranelli and collaborators).

213

For example, in the case presented, the mesiodistal dimension (MD) of the teeth 43 and 33 was 7.3 mm. One can use the table and with a simple rule of three, calculate the height of the crowns of these mandibular canines: if 7mm MD results in a crown with 11 mm of cervicoincisal (CI) length, 7.3mm corresponds to a crown of X mm of cervicoincisal (CI) length. In this example, X= (7.3 x11)/7, which results in a crown height of 11.47 mm for the mandibular canines.This same reasoning is applied to the maxillary canines. Based on the values obtained, the dimensions of the four canines must be rebuild. After the reconstruction, the coupling and the overlapping obtained are checked. When bilateral, simultaneous contacts do not occur with the elimination of the mandibular rocking (a posterior contact does not permit any contact between the canines), one should decide whether the size of the canines will be increased or grinding the posterior contact point will be required. In the case described the simple reconstitution of shape and size of the teeth

in relation to the maxilla, one may focus on the incisor teeth. Typically,  we accomplish the anterior lower teeth. Then we build the maxillary incisors, first the centrals and finally the laterals. Again, the concept of proportion is applied therein (Fig. 20). As mentioned in section 2, the interpupillary distance may be used to obtain an aesthetically ideal width for the central incisors as well as through an aspect ratio, the height of the teeth #11 and #21 which also have been obtained. Often, with the application of different calculation methods the optimal size of our crowns are obtained, it is possible to achieve very similar results.

After the anterior guidance determined, one should take care of the vertical stability when the lifting musculature of the mandible is triggered by the repetitive length of maximum contraction. Explaining better, the posterior contacts with the heads of the mandible lodged the most superior in relation to the fossa as possible are created. In the case of the articulator, this position should be located at the locked terminal axis position. Where appropriate, there are situations in which the alignment discrepancy between the upper and lower arch is greater than the anatomical range of variation which one can use, namely: where it would be necessary to further distort the dental anatomy to provide coincidence between the maximum and dental occlusion mandible heads accommodated in the ceiling of the respective fossa. When the oscillation is exaggerated, alternative therapies such as orthognathic surgery may be suggested. One may also perform tooth reduction and orthodontic movements, but it must be clear that the difference between a terminal condylar axis and maximum intercuspidation should be minimized under the penalty of increased risk towards the onset of temporomandibular disorders29 and increased risk of occurrence of occlusal disease itself.

214

COMPLETE THE PROJECT WITH THE POSTERIOR TEETH

Following the establishment of the vertical and lateral relationships of the mandible

COMPLETE THE INCISAL GUIDE

was enough to put an end to any of the rocking effect of the mandible (Fig. 19).

On the other hand, it is believed to be unacceptable displacements minor than 1 mm, especially if they occur only in postero-anterior direction.It is believed also that the higher mechanical stress on the entire dentition and occlusal system occurs unconsciously, and most of the time, while asleep. Therefore, the use of an occlusal orthosis (plate) may be indicated by aligning teeth and mandible in overloading situations. The patient model again illustrates this type of occurrence. The displacement of the intercondylar axis from the centric position to the maximum tooth contact position can not be completely eliminated only by changing the shape of crowns of teeth. It would be necessary to create true anatomical aberrations to enable such the condylar-occlusal locking. So it was created a project in wax which reduced the slide of the terminal axis from 3.0 mm to less than 1.0 mm. Greater than that, the displacement was guided. If this earlier generated first or second degree levers, after reconstruction by wax-up, condylar sliding occurred along the surface of the articular eminence, avoiding rocking (Fig. 21).

Figure 19.

Figure 20.

Figure 21.

Figure 19. After the anatomical reconstruction of the crowns of the four canines and the upper branch of the articulator locked onto terminal axis of rotation, it was possible to eliminate any rocking or teeter movement of the jaw. The next step is to check the generated overbite. In the case of canines, this overlap may be 3 to 5 millimeters, and must allow disocclusion of the posterior teeth to occur during the lateral movements. The obtained maxillomandibular vertical relationship should be maintained until the end of wax-up. This will be the vertical dimension of occlusion of the rehabilitation. Figure 20. The reconstruction in wax of the anterior guidance is tried during protrusive movement. Being the incisors in a top relationship, the upper branch can be guided laterally and simulate shear. This maneuver also repeated on the lateral guidances by the canine teeth, allows for a functional adjustment. Figure 21. Occlusal rehabilitation project completed. Current technologies allow for testing the application of this design in an absolutely reversible and changeable manner.

215

tact of teeth, the neuromuscular balance (or imbalance) and the spatial relations between the maxilla and mandible, and after the construction of an occlusal rehabilitation project (ORP), the operatory part is reached, namely transporting the project to the mouth. Currently, by combining bonding techniques with bis-acrylic polymers, it is possible to carry what had been determined on the lab bench to the mouth in less than 4 hours of clinical time. This is when the professional is convinced of the value of spending so much time with the diagnosis and the design. The treatment becomes most accurate, from both a biomechanical as well as from an aesthetic point of view. The permanent rehabilitation assay (PRA) is an absolutely reliable way to achieve a long lasting occlusal rehabilitation. For performing a PRA, waxing is initially duplicated with materials such as silicones or

EVOLVING THE DESIGN FOR REHABILITATION

After the occlusal diagnosis, which considered the orthopedic articular axis, the con-

alginates. Specifically in the case of a PRA, one may use a laboratory PVS material (Platinum®, Zhermack, Italy) directly on the waxed models. With the aid of pressure chambers, where it is possible to inject compressed air during polymerization, allowing for extremely precise and detailed guides to be obtained (Fig. 22). As a complement, alginate may be used for duplicating and obtaining the wax-up and stone replicas. On these new models, one may fabricate 0.3 mm thick acetate masks (BioArt®, Brazil) in a vacuum-forming machine. These mask molds have several utilities. They serve for visualization of the extent of the reconstruction, to guide the preparations toward maximal preservation of the remaining tooth structure and further, as molds to be filled with any plastic material which is suitable for reproducing a tooth (Fig. 23).

Figure 22a.

Figure 22b.

Figure 23a.

Figure 22c.

Figure 23b.

Figure 22. PVS walls (Platinum® 85, Zhermack) polymerized under pressure of 2 bar. The capability of detail reproduction in a tough, stable and flexible matrix becomes the greatest ally during the occlusal reconstruction, be it plastic with acrylics, bis-acrylic or composite resins. Figure 23. Acetate shells prepared from the waxed stone model or obtained through mock-up impression.

216

THE OCCLUSAL PLASTIC

Being able to transfer the occlusion of the patient through a mechanical simile is the great asset of this technology. Therefore, the possibility of transporting the result of a project designed on the laboratory bench and back to the patient’s mouth is the basis of the work proposal of this chapter: the plastic occlusal rehabilitation. It is understood that once the final form of the reconstruction is defined, the material which was used becomes a secondary factor. It most likely will not work with plastic materials, nor with prosthetic solutions. Therefore, it was described how to rehabilitate an occlusion almost instantly through the use of PRO, silicone walls, acetate shelves, bis-acrylate and composite resin. In the model case used to illustrate this chapter, the plastic rehabilitation will be replaced by a laminate job using high translucency leucite (IPS Empress® CAD, Ivoclar Vivadent, Liechtenstein) and a nanoceramic resin (Lava Ultimate®, 3M ESPE, USA), using the biocopy option of the Cerec system (Cerec®, Sirona, Germany). That is, the anatomy obtained in wax will be transferred to the mouth of the patient with the use of plastic materials and will be later replaced by longer lasting and more stable materials. In a way similar to the wax-up, this process is initiated in the anterior-inferior sector (sector I). With the aid of polytetrafluoroethylene tape, the segment is isolated and etching is performed only on the incisal third of the teeth (Fig. 24). After rinsing, a multipurpose adhesive (Single Bond Universal®, 3M ESPE, USA) is applied, light cured, and a bis-acrylic resin (Protemp® 4, 3M ESPE, USA) is then applied (Fig. 25 and 26). After the initial polymerization, the silicon wall is removed and separation and individualization of the teeth is performed (Fig. 27 a-b).

Figure 24.

Figure 27a.

Figure 25.

Figure 26.

Figure 27b.

Figure 24. The bonding promoted merely in the incisal third of the teeth allows for to the reconstruction strength and stability and yet, facilitates the future removal. Figure 25. With the aid of the gun and the specific mixing tip, the activated bis-acrylate is dispensed in the silicon wall, in the corresponding area from incisal to cervical. Then, the impression is taken to the mouth. It is expected 2 to 3 minutes until the initial polymerization to occur. Figure 26. After removing the silicone impression, the coarser cervical excesses are removed and finishing and individualization of the teeth are carried out. Figures 27a-b. Ceri-Saw blade handle (DenMat®, USA), diamond discs (Komet®, Germany) , diamond points and multilaminated steel burs (Komet®, Germany and KG®, Brazil) are used to promote the individualization of teeth.

217

Figure 28.

Figure 29a.

Figure 29b.

Figure 30a.

Figure 30b.

Figure 31a.

Figure 31b.

Figure 31c.

Figure 31d.

Figure 28. If the interocclusal record and mounting of the models in the articulator was careful, if the wax-up was meticulous, as well as the construction of the guides in acetate and silicone, if the application of rehabilitation materials (in this case, bis-acrylate) was diligent, the designed fit for the anterior guidance should be found (segments 1 and 2). Figure 29a-b. Identical to the segments 1 and 2, when applying bis-acryl on segment 3, bilateral inferior-posterior, selective bonding is performed previously, concentrated in the area that should receive more occlusal loading. Figure 30a-b. With the aid of selective bonding, composite resin veneers (Z350® XT XWE, 3M ESPE, USA) are instantly made. Figures 31a-c. With the occlusal plastic in bis-acryl, the patient could test the arrangement established during the planning of the case, not only in the aesthetic sense, but especially in the biomechanical sense. The final treatment for the case could wait for weeks to be sure what we is being made.

218

Upon completion of the segment corresponding to the six anterior-lower teeth, the same steps are repeated in the antagonist, ie, the anterior superior teeth (Fig. 28). Due to the aesthetic role performed by this segment one must be be prepared for anatomical changes by additioning or removing after the polymerization of the wax-up copy. This appears to be the major advantage of this method: the ability to test a rehabilitation design in all of its occlusal, aesthetic and phonetic aspects, and most importantly, to be able to make in loco changes at any moment. During the planning of the rehabilitation of the patient model, it was decided that the entire occlusal addition would be carried out on the posterior mandibular teeth. This option was taken due to little available interocclusal space, especially between the molars on the left side (Fig. 29a-b). To further illustrate the possibilities of implementing a plastic occlusal rehabilitation, in the treatment sequence of the patient-model, we chose to use acetate shelves in combination with composite resin (Z350XT® XWE, 3M ESPE, USA) (Fig. 30a-b). As informed earlier, in the posterior-superior teeth (Segment 4) occlusal additions would not be necessary. Composite resin veneers, along with selective bonding, are to complement the planned arrangement. At the end of the plastic rehabilitation, a new arrangement is obtained. The mandible is repositioned, the teeth are reshaped, and the muscles reprogrammed. This new anatomy may be replaced in an intensive or progressive manner. In the case of patient-model, an entirely CAD/CAM job awaits. But that’s just technology. With the recovered shape, there will

THE COPYED REHABILITATION

be more and more ways of keeping it (Fig. 31a-c).

It is not within the scope of this chapter the description of the restorative technique. However, it is necessary to illustrate the finalization of the work. As stated earlier, once the final form of rehabilitation has been established, it may be copied with more durable or aesthetic materials. In the case described in this chapter, the bis-acrylate rehabilitation remained in the mouth over 45 days. During this period, the patient could test the job in all of its aspects: biomechanical, aesthetic and phonetic. After the test period, with the aid of a CAD/CAM system (Cerec®, Sirona, Germany), the interim bis-acrylic rehabilitation was gradually replaced. In the maxillary and mandibular anterior teeth, all-ceramic leucite-reinforced B1-colored high translucency partial laminates (IPS Empress® HT B1, Ivoclar Vivadent, Liechtenstein) were obtained by biogeneric copy and milling.Extrinsic characterization and glazing were carried out, and cementation (+2 Value, Variolink Veneer®, Ivoclar Vivadent, Liechtenstein] (Fig. 32 to 36). In the posterior mandibular teeth (from the first premolars to the second molars) genuine occlusal ceramized resin veneers were fabricated (Lava Ultimate® HT B1, 3M ESPE, USA). The biogeneric copy process was also employed, and the cementation of these pieces was performed (RelyX Ultimate®, 3M ESPE, USA) (Fig. 37 to 39).

219

Figure 32.

Figure 33b.

Figure 33a.

Figure 34.

Figure 35.

Figure 36.

Figure 32. After scanning the contour of the bis-acryl, the teeth can be prepared and then scanned again. The crown or veneer will be the copy of the original contour of the “unprepared” tooth. Figure 33a-b. The final virtual design of a double veneer and the milled veneer. During the design, the insertion axis can be virtually tested. Figure 34. A faithful copy of the design sculpted by the Cerec system® (Sirona, Germany) previously treated and ready for adhesive cementation. Figure 35. The lower segment also labored in IPS Empress® CAD system (Ivoclar Vivadent, Liechtenstein), copied the shape of the rehabilitation trial. Figure 36. Result after the adhesive cementation of the maxillary and mandibular anterior teeth.

220

Figure 37.

Figure 38.

Figure 39.

Figure 37. The preparation of the occlusal veneers was accomplished on the restorative bis-acryl test. Note that the mere thickness of the bis-acryl already allows for prosthetic restorations. At this point, preserve the enamel-dentin junction should be an obsession. Figure 38. Finalized the preparations, the maximum enamel is maintained. The cervical restorations were also preserved in order to allow for insertion axis of the final restoration. Figure 39. The double veneers (occlusal-buccal) after finishing, characterizations and final polishing.

One may consider the main objectives of the occlusal rehabilitation to be the establishment and recovery of the beauty of a smile and the comfort of mastication. The binomium function and the aesthetics are repeated to exhaustion and frequently stops making sense for Dentistry. It is expected that this chapter has illustrated the indissoluble relationship between morphology and dental performance. When comparing the initial and final smile (Fig. 40a-b) the intraoral pictures (Fig. 40c), and reviewing the patient’s report of comfort while chewing increased considerably, it may be concluded that all of the goals of treatment at this magnitude were fully achieved (Fig. 41a-g). 221

Figure 40a.

Figure 40b.

Figure 40c.

Figure 41a.

Figure 41b.

Figures 40a-c. The comparison of the initial and final photos leave no doubts as to the aesthetic gain. However, treatment will only be fully justified if there is gain in performance, and balance and comfort of chewing as well. Figures 41a-f. Initial facial photographs for comparative analysis and final photos after cementation of overlays (Lava Ultimate® CAD/CAM, 3M ESPE, USA) and installation of ceramic veneers (IPS Empress® CAD, Ivoclar Vivadent, Liechtenstein) with palatal extension for the maxillary and mandibular anterior teeth, demonstrating an aesthetic rehabilitation based on principles and aesthetic references, as well as a long-lasting functional rehabilitation. Photographs taken by Dudu Medeiros.

222

Figure 41c.

Figure 41d.

Figure 41e.

Figure 41f.

223

Photography performed by Dudu Medeiros.

224

REFERENCES

1. Lyttle J. The Clinician’s Index of Occlusal Disease: definition, recognition, and management. J Perio Rest Dent. 1990;10(2):102-23. 2. Sato S, Sasaguri K, Ootsuka T, Saruta J, Miyake S, Okamura M, et al. Bruxism and stress relief. In: Onozuka M, Yen CT, editors. Novel trends in brain science: brain imaging, learning and memory, stress and fear, and pain. Tokyo: Springer; 2008. p. 183-200. 3. Magne P, Gallucci G, Belzer U. Anatomic crown width/length ratios of unworn and worn maxillary teeth in white subjects. JPD. 2003;89(5):453-61. 4. Buonocore M. A simple method of increasing the adhesion of acrylic filling materials to enamel surfaces. J Dent Research. 1955;34(6):849-53. 5. Lauritzen AG. Atlas de analisis oclusal. Madrid: H.F. Martínez de Murguía; 1977. 6. Moyers RE. An electromyographic analysis of certain muscles involved in temporomandibular movement. Am J Orthod. 1950;36(7)481-515. 7. Pereira M. Saúde e doença. In: Epidemiologia: teoria e prática. Rio de Janeiro: Guanabara Koogan; 1995. p. 30-48. 8. Nakata M. Masticatory function and its effects on general health. Int Dental J. 1998;48:540-8. 9. Huynh N, Kato T, Rompré PH, Okura K, Saber M, Lanfranchi PA, et al. Sleep bruxism is associated to micro-arousals and an increase in cardiac sympathetic activity. Sleep Res. 2006;15(3):339-46. 10. Bartlett D. The role of erosion in tooth wear: etiology, prevention and management. Int Dental J. 2005;55:277-84. 11. Sobral MAP, Luz MAAC, Gama-Teixeira A, Garone Netto N. Influência da dieta líquida ácida no desenvolvimento de erosão dental. Pesqui Odontol Bras. 2000;14(4):406-10. 12. Grippo JO. Abfractions: a new classification of hard tissue lesions of teeth. J Esthet Dent. 1991;3:14-9. 13. Dawson P. Occlusal disease in funcional occlusion. St. Louis: Mosby; 2007. 14. Christensen LV, Donegan SJ, Mckay DC. Temporomandibular Joint: vibration analysis in a sample of non-patients. J Craniomandib Prac. 1992;10:35-41. 15. Gervais R, Fitzsimmons GW, Thomas NR. Masseter and temporalis electromyographic activity in asymptomatic, subclinical, and temporomandibular joint dysfunction patients. J Craniomandib Prac. 1989;7:52-7. 16. Dawson P. Position paper. In: Celenza FV, Nasedkin JN. Oclusion: the state of the art. Chicago: Quintessence; 1978. 17. Lucia VO. Position paper. In: Celenza FV, Nasedkin JN. Oclusion: the state of the art. Chicago: Quintessence; 1978. 18. Posselt U. Physiology of occlusion and reabilitation. Oxford: Blackwell Scientific; 1968. 19. Williamson EH, Lundquist DO. Anterior guidance: its effect on electromyographic activity of the temporal e masseter muscles. J Proth Dent. 1983;49(6):816-23. 20. Ren YF, Isberg A, Westesson PL. Condyle position in temporomandibular joint: comparison between asymptomatic volunteers with normal disk position and patients with disc displacement. Oral Sur Oral med Oral Oathol Oral Raiol Endod. 1995;80:101-7. 21. Muratsu K, et al. Remarkable improvement of persistent period of time under standing on one foot with closure of eyes by dental occlusion. Jap J Dent Health. 1997;4(27). 22. Berry D, Poole D. Attrition: possible mechanisms of compensation. J Oral Rehab. 1976;3:201-6. 23. Dawson P. Vertical dimension in functional occlusion. St Louis: Mosby Elselvier; 2007. 24. Dos Santos J, Nelson S, Nowlin T. Comparison of condylar guidance setting obtained from a wax record versus an extra-oral tracing: s pilot study. J Proth Dent. 2003;89:54-9. 25. Harrel SK, Nunn ME, Hallmon WW. Is there is an association between occlusion and periodontal destruction?: yes, occlusal forces can contribute to periodontal destruction. JADA. 2006;137:1380-92. 26. Kerstein RB, Wright N. An Eletromiographic and computer analysis of patients suffering from chronic myofacial pain dysfunction syndrome: pre and pos-treatment with immediate complete anterior guidance development. J Proth Dent. 1991;66:67786. 27. Alonso AA, Albertini JS, Bechelli AH. Oclusión y diagnóstico en rehabilitación oral. Buenos Aires: Médica Panamericana; 1999. 28. Vieira GF. Atlas de anatomia de dentes permanentes. São Paulo: Santos; 2009. 29. Maruyama T, Miyauchi S, Umekoji E. Analysis of the mandibular relationship of TMJ dysfunction patients using the Mandibular Kinesiograph. J Oral Rehabil. 1982;9(3):217-23.

225

SECTION III. IMPLEMENTATION

ON THE SIZE | ON THE CERAMIC SYSTEM | ON THE IMPRESSION-TAKIING | ON THE PROVISIONAL RESTORATION

chapter 6.1

preparation for ceramic veneers Rafael de Almeida Decurcio | Paula de Carvalho Cardoso | Lúcio Monteiro Marcus Vinícius Perillo | Wilmar Porfírio de Oliveira | Terence Romano

paration were designed for use with metallic restorative materials and being non adhesive, out of the necessity for preparations with a geometric shape retention and resistance with greater loss of tooth structure. However, the evolution of restorative materials and adhesive systems driven by the insaciable social desire for aesthetic results gave birth a new dental

INTRODUCTION

Devised by Black, in 18914 the principles of “extension for prevention” for cavity pre-

age, providing the manufacturing of all-ceramic restorations with functional, durable and  aesthetic results.8,37 These advances have allowed for the application of modern restorative principles: (1) maximum preservation, (2) maximal prevention and (3) minimal wear.9,23 This new philosophy of “prevention for extension” seeks to minimize the biological cost of the natural tooth as a whole43 and  culminates in the modification of traditional preparations and creation of a new classification for ceramic veneer veneers: ON THE SIZE • TOTAL: involvement of the entire surface (labial, palatal or occlusal) WITHOUT PREPARATION: use of thin ceramic veneers (0.1 mm to 0.7 mm thick) over the tooth structure with minimal or no wear, and strongly bonded to tooth enamell.7 n this technique, the restorative design of ceramics are guided exclusively by pre-existing defect in the tooth to be restored, as, for example, corrections of the shape and incisal edge, fractured and conoid teeth, with small diastemata and parallel walls, reestablishment of the anterior and/or canine guide, and vertical dimension increase. WITH PREPARATION: conventional veneers which require making preparations with labial, proximal, incisal and occlusal reduction. Indications include teeth which are proclined, rotated, misaligned, or discolored, replacement of defective composite resin veneers and production of adequate prosthetic room in posterior teeth for increasing the vertical dimension of occlusion. • PARTIAL (fragment type): without involvement of the entire surface WITH PREPARATION WITHOUT PREPARATION The longevity of rehabilitated cases with ceramic veneer veneers - most importantly associated with the conservative concept of minimal preparations – became over the years a great ally in the indication process. The high success rate of ceramic veneer veneers observed in clinical studies is directly related to the bonding of the dental substrate, especially enamel, which explains the need to preserve that structure.5,28 This means that the greater the amount of enamel, the better the adhesion, and consequently, more predictable and the longer lasting becomes the rehabilitation process. Ideally, the preparation should be confined to enamel, or maintain 70% of enamel on the surface, especially along the preparation margins.33,36 Cementation failures which cause the displacement of ceramic veneer veneers have been reported in preparations where 80% of the location is made up of dentin. These failures are unlikely to occur when the minimum of 0.5 mm enamel is present peripherically.19

230

The deepest preparations, as in proclined, misaligned, or discolored teeth with severe occlusal wear can reach dentin and lead to lower bond strength values and poor durability.10 In such situations, one must evaluate the thin line between choosing veneers or crowns, as the presence of a substrate eminently in dentin tends to the need for additional mechanical retention such as a crown preparation, which results in greater predictability as well as the longevity of the treatment.38 It is worth remembering that a full ceramic veneer, with preparation, can still be considered a conservative treatment, since a full crown requires more sacrifice of tooth structure; therefore, whenever possible, one should expand the range of indications of these veneers, by linking them to the conservation of tooth structure and high clinical success rates. Is worth mentioning that in the modern restorative concept two factors are crucial for the success of ceramic restorations: understanding dental anatomy and vision of the final restorative dimension. These factors should be considered before any mechanical dental change. The first consideration, the extensive knowledge of dental anatomy, can provide is an objective basis for dental preparation. It is essential to have knowledge of the mean thickness of enamel, because maintaining this structure implies superior bonding values and increased longevity of the rehabilitation procedure. Whenever possible, given the specificity of the case, it is essential for maximum enamel preservation as well as greater predictability and longevity.1 The second consideration, the vision of the final restorative dimension, can prevent extensive removal of tooth structure. The amount of tooth reduction must be carried out according to the final anticipated volume of the contour of the restoration. The diagnostic wax and the mock-up (Chapter 4) are essential to provide changes in the size, shape and dental contour, providing the necessary dimensions of the desired preparations before the restorative procedures.21,22 This technique offers a more conservative approach to cavity preparation.

231

The original concept was developed in 1938 by Pincus, which describes a technique for masking defects and improving the appearance of the teeth for American actors using plastic or porcelain veneers to be maintained by an adhesive solely during footage. In the late 1970s, a prefabricated acrylic veneer, chemically joined to the tooth structure by a thin layer of self-curing composite resin was recommended by Faunce and Myers.13 The concept of making and cementing porcelain veneers was introduced in the 1980s. While Horn25 described the procedures for manufacturing and cementation, the studies of Simonsen and Calamia39 supported and provided the protocol data of the procedure and the time for the surface conditioning of the ceramics (hydrofluoric acid and silane agent) to improve adhesion. In the decades of the 1990s and 2000s, preparation for veneers were largely performed.

29,34

The assumption was to replace the amount of enamel prepared with a material

with a similar modulus of elasticity,6 one of the reasons for the success of this approach. Currently, there is a philosophy guided by modern restorative principles: (1) maximum preservation, (2) maximal prevention and (3) minimal intervention. This last once again stimulated the return of the luting approach of ceramic veneers with no or little wear (in retentive areas).9,23 Although conceptually related to optics/ophthalmology and manufacturing mechanisms, using this term has nothing to do with Dentistry, the term “contact lenses” was incorporated into the world of cosmetic dentistry, and ceramic veneer veneers without wear are popularly known as such.31 Each and every sharp edges should be removed in order to eliminate any potential structural stresses at the moment of the ceramic seating. Average grit aluminum oxide based discs are the most suitable for carrying out the smooth off the edges. Indications for total ceramic veneer veneers without preparation are: • corrections of the incisal edge (Fig. 1); • fractured teeth (Fig. 1); • conoid teeth (Fig. 2); • diastemata with parallelism of the faces involved (Fig. 3 e 4); • teeth with enamel loss by non shallow carious lesions (Fig. 5); • teeth in need of labial volume increase for improved lip volume or orthodontic post treatment with lingually placed crowns (Fig. 6); • restoration of the incisal length to improve function (anterior and/or canine guide); • occlusal restoration (Fig. 7); and • tilting correction (labial-palatal) of contralateral teeth. Contraindications for full ceramic veneers without preparation are: • Insufficient superficial enamel; • discolored teeth; • proclined teeth; • crowded teeth; and • restored teeth. 232

PREPARATIONS FOR ALL-CERAMIC VENEERS

PREPLESS OR “CONTACT LENS”

Figure 1a.

Figure 1b.

Figure 1c.

Figure 1d.

Figure 1e.

Figure 1f.

Figure 1g.

Figure 1. Initial smile revealing the presence of interincisal diastema, Class IV restoration and presence  of worn incisal edges (a); detail of the staining of class IV and III composite resin restorations (distal) in tooth #11 (b);palatal aspect revealing the extent and staining of the Class IV restoration (c); frontal view after removal of class IV and III restorations (d); palatal aspect after removal of the defective restoration (e); incisal view after cementation of ceramic veneers from 13 to 23. Observe the continuity and biomimetism reestablished by the ceramic (f) and the final smile demonstrating naturalness. (g)

233

Figure 2b.

Figure 2a.

Figure 2c.

Figure 2d.

Figure 2e.

Figure 2f.

Figure 2g.

Figure 2h.

Figure 2i.

Figure 2. Initial facial aspect showing disharmony (a); Initial frontal smile with the presence of diastema between anterior superior teeth and conoid teeth(b), initial left (c), initial right (d); Initial intraoral photograph revealing the details of the initial condition (e); prepless ceramic veneers or “contact lenses” cemented on teeth 13 to 23 (f); Final frontal aspect of the smile (g); Final left (h); Final right (i) and final aspect of the face showing a state of total harmony and aesthetic and functional reestablishment.

234

Figure 2j.

235

Figure 3a.

Figure 3b.

Figure 3c.

Figure 3d.

Figure 3e.

Figure 3f.

Figure 3g.

Figure 3h.

Figure 3i.

Figure 3j.

Figure 3k.

Figure 3. Initial protocol photography for the initial facial analysis (a); Initial smile demonstrating gingival display greater than 3 mm and generalized diastemas (b); ideal exposure at rest for women (c); note the parallelism of the diastema between the incisors and presence of teeth #14 and #24 slightly proclined (d); aspect of the smile after 120 days of periodontal surgery with flap raise-up from #16 to #26 (e); detail of whiter teeth after bleaching by the association of techniques (f); after new mock-up and approval of the patient, impression was carried out with no reduction of tooth structure and preparation of ceramic veneers from 15 to 25 (g); frontal aspect after cementation (h); analysis at rest after rehabilitation with the total prepless ceramic veneers (i); final smile (j); and final aspect of the face in total harmony (k); beauty as a whole (l). Facial photographs taken by Dudu Medeiros.

236

Figure 3l. Photography taken by Dudu Medeiros.

237

Figure 4b.

Figure 4a.

Figure 4c.

Figure 4d.

Figure 4e.

Figure 4f.

Figure 4g.

Figure 4h.

Figure 4. Initial protocol photography (a), analysis at rest (b); Initial smile revealing multiple diastema (c); intraoral aspect with small spacing, and parallel to each other (d); result after cementation of full ceramic veneers without preparation from 15 to 25 (e); details of vertical and horizontal texture reproduced in the ceramic veneer (f); final smile (g); final protocol photograph of the face (h); and the beauty transmitted by the smile (i). Ceramist responsible: José Carlos Romanini. Photographs of the face by Dudu Medeiros.

238

Figure 4i. Photography taken by Dudu Medeiros.

239

Figure 5b.

Figure 5a.

Figure 5c.

Figure 5d.

Figure 5e.

Figure 5f.

Figure 5g.

Figure 5h.

Figure 5 Smile frontal face shows aesthetic disharmony and aged aspect (a); Initial smile photo reveals dental darkening and curve not parallel incisal edge with lower lip (b); the intraoral photographs confirm the dull aspect and generalized loss of enamel, caused by the habit of lemon sucking (c-d); aspect after cementation of the veneer of tooth #21. Notice that the “contact lens” restored lost enamel (e); ideal analysis at rest with an average exposure of 3.4 mm (f); final radiant smile (g);facial photograph of protocol (h);and face with a new smile (i).

240

Figure 5i.

241

Figure 6b.

Figure 6a.

Figure 6c.

Figure 6d.

Figure 6e.

Figure 6f.

Figure 6. Initial protocol photograph of the face (a); Initial smile after orthodontics demonstrating that the spaces were distributed, however lacking tooth volume, the teeth are short and absence of any dominance of the centrals (b); observe in the intraoral figure the presence of changed gingival contour (c); after mock-up, periodontal surgery, and bleaching, the impression for the manufacture of full ceramic veneers without preparation was carried out. Notice that the “butterfly pattern” of the distal aspect of the centrals was selected to promote the optical illusion of broader teeth and hence higher dominance for the centrals (d); Final smile revealing a new arrangement, younger and more radiant (e); final protocol photograph of the face (f); and art and naturally in the face, smile, teeth and gingiva set (g). Facial photographs taken by Dudu Medeiros.

242

Figure 6g. Photography performed by Dudu Medeiros.

243

Figure 7a.

Figure 7b.

Figure 7c.

Figure 7d.

Figure 7e.

Figure 7f.

Figure 7g.

Figure 7h.

Figure 7i.

Figure 7.Young patient presented with aged smiling and lack of labial volume after orthodontic treatment.After thorough planning with facial analysis, there was skeletal deficiency, of familial background, in the lower third, however without loss of the vertical dimension of occlusion. Note the presence of deficient composite resin veneers from canine to canine (a); Detail of the staining and poor shape of the veneers composite resin (b); after removal of composite resins, there is the presence of widespread diastemas and conoid teeth (c); the taper of the diastema and conoide tooth favored the realization of ceramic veneers without preparations with palatal involvement, aka “full veneers”. Thus, there was only the impression without any wear of tooth surfaces, and mounting on SAA for the manufacture of occlusal ceramic veneers and “full veneers” (d); observe the details of the occlusal veneers extending towards the labial on the model without any preparation (e); detail for the “full veneers” of teeth 11 and 21 (f); notice the thin occlusal veneers of the premolars extending towards the labial (g); result immediately after cementation (h); and final smile demonstrating naturalness and youthfulness (i).

244

It is worth remembering that the final objective and the thickness of the restorative material should be considered to avoid overcontour of the restored teeth. Another consideration is the amount of masking required on the dental structure. Several discolorations could require considerable thickness of restorative material and as a result, a more invasive tooth preparation result and to determine the final thickness and morphology of the tooth and of the restoration. Some of the advantages of the prepless veneers in relation to conventional veneers (with preparation) are the preservation of sound tooth structure, reduced clinical time for the impression taking step, the elimination of the provisional step and bonding exclusively to enamel. Disadvantages are the meticulous and thorough manufacturing of the laboratory step, increased risk of fracture during the various steps of the process (laboratory, try-in and cementation) due to thinness of the veneer, critical cementation process and thoughtful maintenance therapies, concerning the maintenance of the aesthetic result, considering that prepless veneers do not involve the areas of dynamic visibility, which will become visibly present with the natural darkening of the dental substrate. CONVENTIONAL OR WITH PREPARATION Preparations for ceramic veneers have undergone many changes and advances. The preparation shape can be influenced by tooth shape, location and orientation in the arch, tooth anatomy, occlusal function, mechanical forces, quantity and quality of the remaining tooth structure and anticipated final restorative dimension.21,22,41,42,11 By using these clinical considerations, modifications in the preparation shapes may be varied and find a multitude of shapes, being guided by the pre-existing defect or depending on the anticipated dimension of the final restoration and the substrate shade. Indications for ceramic veneers with full preparation are: • discolored teeth; • restored teeth; • proclined, rotated or misplaced teeth; • large diastemata and involved walls converging to incisal; and • occlusal restorations for the reestablishment of the vertical dimension of occlusion. Contraindications include: • extensively restored teeth; • presence of large amounts of dentin in the post-preparation substrate; and • Severely discolored single tooth (more than four tones). When the preparation is necessary, the depth of wear has a direct influence on the establishment of the desired ceramic veneer shade after cementation. A 0.9 mm wear of the substrate is capable of promoting a change from an A4 shade to an A1 shade (Vita Classical® shade guide, Vita, Germany); a reduction of 0.5 mm creates a shift from an A4 to an A2; a reduction of 0.3 mm does not produce any color change; rather, final color adjustments with resin cement are necessary.22

245

Figure 8.

Figure 8. A  0.9 mm reduction of the substrate is able to promote change in color from an A4 to an A1 (Vita Classical® shade guide, Vita, Germany); an reduction of 0.5 mm creates change from an A4 to an A2; and an of 0.3 mm reduction does not produce any color change

Despite a multitude of preparation methods, always guided by the pre-existing defect or by the restorative morphology planned the protocol for ceramic veneers with specific preparations should didactically follow the following. 1. Control of reduction with silicone guides. The preparation design for ceramic veneers should allow for an optimal marginal adaptation of the definitive restoration and maximally resembling the ideal tooth morphology. Therefore, a diagnostic wax-up should be utilized as a reference for tooth reduction. Silicone guides, fabricated over the wax-up, provide simple and indispensable tools for control and in reduction of enamel.21,22 Two guides should be fabricated: a vertical guide (sectioned in the buccolingual direction) for reduction control in cervicoincisal direction; and a horizontal guide for the mesiodistal reduction control. With teeth darkened by endodontic treatments in which the labial surface is intact and the rehabilitation of which will maintain the natural morphology, the silicone guide may be fabricated directly within the mouth and prior to preparation.2,3 (Fig. 9) 246

Figure 9a.

Figure 9b.

Figure 9c.

Figure 9d.

Figure 9e.

Figure 9f.

Figure 9g.

Figure 9. PVS impression material (Elite HD, Zhermack, Italy) for manufacturing the preparation guides (a); Diagnostic wax-up (b); obtaining two guides for the manufacture of horizontal and vertical reduction guides (c);cutting on the buccal surface of the medial portion (d) for building the vertical reduction guide (e); conference of the reduction vertical guide on the diagnostic wax-up (f) and horizontal reduction guide obtained with three slices carried out in the cervical, middle and incisal thirds (g).

247

2. Peripheral delimitations of the preparation with spherical diamond burs surrounding the entire labial surface of the tooth without disruption of the proximal contact and without subgingival extension (Fig. 10e). New diamond burs, a kit of handpieces (high speed, low speed, micromotor and a multiplier) which lend stability to the preparation and polishing process, without variation in the axis of rotation of the diamond tips, aluminum oxide discs and finishing and polishing rubbers are fundamental for a preparation without risks and a smooth and regular surface. (Fig. 10f -h) 3. Preparation of vestibular grooves in the vertical direction with rounded-ended conical diamond burs (FG 2135, KG Sorensen®, Brazil), respecting the axial inclinations (cervical, middle and incisal) to preserve the convergence of the buccal surface. (Fig. 10i) The depth of each groove is defined according to each case and based on the diagnostic wax-up. Another modality of vestibular groove preparation is to perform a central groove respecting the same concepts of axial inclinations, for posterior wear of only one of the sides until the limit of the contour peripherically. (Fig. 10j) In this way, one can check the amount of wear with a millimeter probe by comparing the prepared side with the intact. At this point, it is essential to have knowledge about the thickness of the labial enamel of a natural tooth, so that the completion of the preparation is performed, having also the preservation of enamel as a guide whenever possible.14 (Fig. 11) 4. Joining the labial grooves with a conical diamond bur, the larger diameter to prevent deepening of the guide grooves and forming an uneven surface. (Fig. 10k) 5. Performing the proximal preparation with a diamond bur of smaller diameter (Fig. 10l). The protection of the adjacent teeth with metal matrix is imperative. The proximal extension of the preparation is directly associated with the static and dynamic area of visibility and preexisting restorations. The observation of the preparation in a static way, merely by labial, gives a false impression that all visible areas of the substrate were included in the preparation. Thus, the dynamic view of the preparation laterally enables an actual verification on whether or not to proximally extend the preparation. (Fig. 10m-o) This stage is characterized as one of the most conflicting points with the pragmatism of conventional preparations for fixed prosthesis, performing reduction to enable insertion axes and elimination of retentions. It is essential to understand the fact that the majority of cases of ceramic veneers with or without preparation, presents a passive fit in the labial-palatal direction, and the supposed interproximal retentions are overlooked when veneers “fit in” without resistance. In this way, it is possible to carry out more conservative interproximal preparations, restricted mainly to the cervical region even if retentions exist when viewed pragmatically in an incisocervical sense. 6. The incisal reduction of preparation. Incisal terminations, as highlighted in Figure 10p, may be defined as: 0°, straight, 45º and chamfer. The traditional clinical recommendations are: 0º for ceramic fragments; straight and 45º for conventional or prepless veneers (Fig. 10p); and chamfer for specific conventional veneers, such as those with a very thin incisal thickness, need for rebuilding from 1.0 mm to 2.0 mm volume of restorative material in the incisal, presence 248

of structurally compromised incisal enamel and individuals with incisal parafunction subject to functional stress. The 0º termination is critical because of the difficulty in the cementation process. Furthermore, it may result in an aesthetic problem due to the fact that the preparation finishes in the most translucent area of the tooth. This is indicated in cases of substrates with a desired value without chromatic alteration in the incisal region. The chamfer termination, although the preparation is slightly extended to the lingual surface increasing the total surface of enamel for bonding, at the same time also creates the correct path for insertion during the try-in and cementation.15-17 The authors do not advocate performing this termination because the biological cost is higher. Creation of an insertion path facilitates the cementation step, however promotes a higher volume of wear, particularly in the proximal regions to eliminate retentions. Hence, straight-type incisal terminations are preferably chosen when reduction is necessary, because it advocates a passive fit in the the labial-palatal direction without a deliberate insertion axis, greater preservation of tooth structure and lends absolute confidence in the bonding mechanisms. 7. Checking the incisal reduction. Positioning of the vertical guide to check the incisal space should be at least 1.5 mm.2,3,18,30,32,20 The incisal involvement offers many advantages,30 above all by the possibility of incorporating incisal characterizations such as translucency, evidence of the spindles and of the opacity of the halo to the restorations, mimicking its naturality. (Fig. 10q) 8. Preparation of the subgingival cervical margin and initial finishing of the preparation in indicated situations with rounded-ended diamond burs (F or FF series, KG Sorensen®, Brazil) using a multiplier. It is worth to emphasize the importance of gingival tissue protection during preparation, in order to prevent post-traumatic gingival recession, especially in thin marginal tissue. (Fig. 10r) 9. Finishing and polishing of the preparation with abrasive silicone rubbers (Composite Technique Kit®, Shofu, Japan) with decreasing granulation. Every angle and corner should be uniform, with rounded lines, to improve the adaptation of the resin cement and laboratory build-up. In addition, healthy tooth structure must be removed when the contour requires extension to a point beyond or within the functional stops previously indicated.42

249

Figure 10a.

Figure 10b.

Figure 10c.

Figure 10d.

Figure 10e.

Figure 10f.

Figure 10g.

Figure 10h.

Figure 10i.

Figure 10j.

Figure 10. Photography at rest showing an ideal condition (a); harmonic smile presenting only the 11 tooth with tooth darkening caused by an unsuccessful endodontic treatment (b); intraoral aspect of tooth 11 (c); shade selection (d); peripheral delimitation with spherical diamond point (e); Ceramic Veneers burs set - Dentistry ABO Goiás (KG®, Brazil) (f); preparation performed with high speed turbine with LED lighting (W&H®, Austria) (g); contra-angle with LED light and multiplier (W&H®, Austria) (h); preparation of the orientation grooves with a rounded-ended conical diamond point (i); the orientation grooves must follow the three inclinations of the tooth. Note that the natural teeth have three slopes: 1- cervical third, 2- middle third and 3- incisal third (j); joining of the orientation grooves (k); proximal involvement by the presence of an extensive renovation on the mesial aspect (l); Notice that when the proximal reduction is insufficient, it can be seen clearly in the dynamic view the bonding line of the veneer with the darkened substrate (m); thus, the ideal would be to extend the preparation more proximal, and thus the dynamic view area would be appropriate (n); vision of dynamic visibility of the preparation; the incisal terminations described in the literature are 0 °, straight, 45 and bevel (p); note the appearance of the straight termination (q); subgingival extension prepared with fine diamond burs positioned in the multiplier (r); after polishing of the preparation, the previously fabricated wear guides are positioned on the darkened tooth. In this clinical case the wax-up was not needed since the shape of the tooth was adequate; horizontal guide of the incisal third (s);horizontal guide of the middle third (t); horizontal guide of the cervical third (u); vertical guide (v); after approval of preparation, the impression and confection of the feldspathic porcelain is carried out. Note the detail of the smile after cementation (w) and intraoral view of the finished case (x-z). Responsible ceramist: Leonardo Bocabella.

250

Figure 10k.

Figure 10l.

Figure 10m.

Figure 10o.

Figure 10n.

0o

Straigth

45o

Chamfer

Figure 10p.

Figure 10q.

Figure 10s.

Figure 10r.

Figure 10t.

Figure 10u.

251

Figure 10v.

Figure 10w.

Figure 10x.

Figure 10z.

Incisal Third

Middle Third

Cervical Third

1.0 - 1.3 mm

0.8 mm

0.4 - 0.6 mm

Figure 11.

Figure 11. Note that the average thickness of enamel at the incisal third of a central incisor is 1.0 mm to 1.3 mm; in the middle third, 0.8 mm; and the cervical third, 0.4 mm.

252

Degree of darkening Tooth darkening, or above all in an isolated tooth, represents a major challenge for the restoration of optical characteristics with the naturalness of adjacent teeth as a reference. In this case, the alternatives for establishing a good result are performing a more invasive preparation (Fig. 12), using opacifiers before the impression taking, the selection of a less translucent ceramic, with masking capability of the darkened substrate, the use of more opaque and/or higher value resin cements, and also the combined use of the afforementioned alternatives.1,38 Conceptually, the rehabilitation of darker teeth requires greater preparation depth; however, the challenge of conservatism is to remove a minimal amount of tooth structure, and at the same time avoid the risk of inadequate tooth reduction for the proposed ceramic restoration. Until recently, severely discolored teeth represented a situation of contraindication for veneers. However, the improvement of ceramic systems and the association of new ingots with a higher control of light transmission have enabled performing more conservative techniques as well as build-ups on discolored substrates with an increasingly more natural result.9 Wherever possible, the use of ceramic veneers on discolored substrates need to provide a balance between its capacity to mask the substrate and the final aesthetic result. Increased thickness of the restoration and the use of a lower translucency ceramic collaborate with the masking. However, increased thickness necessarily means more invasive tooth preparation, which reduces the amount of enamel available for bonding procedures, thus decreasing the clinical success expected for the porcelain veneer. Currently, the dental market makes available a range of ceramic systems with different degrees of translucency, suitable for the manufacture of ceramic veneers. Excessively opaque ceramics such as E-max®, MO (medium opacity) and HO (high opacity) (Ivoclar Vivadent, Liechtenstein) are uncapable of simulating the optical behavior of tooth enamel, which is characterized by its translucency, lending to restorations an artificial, unsightly appearance. Hilgert,24 studied the ability of ceramic veneers to mask discolored backgrounds in an aesthetically acceptable manner with decreased biological cost, concluded as follows: (1) for non discolored substrates, such as A1 (Vita Classical® shade guide, Vita, Germany), high translucency ceramic systems with a thin thickness may be reliably utilized (0.4 mm) - Empress Aesthetic® HT (Ivoclar Vivadent, Liechtenstein) and E-max® HT (Ivoclar Vivadent, Liechtenstein); (2) slightly discolored substrates (A3,5 VitaClassical® shade guide, Vita, Germany) were masked acceptably with a conservative preparation (0.4 mm reduction), if associated with low translucency ceramics (EmpressCAD® LT, Ivoclar Vivadent, Liechtenstein); and (3) severely discolored substrates (C4, VitaClassical® shade guide, Vita, Germany) were restored acceptably by merely executing an invasive preparation (1.0 mm) and low translucency ceramics (EmpressCAD® LT, Ivoclar Vivadent, Liechtenstein). (Fig. 13a-b)

253

Figure 12a.

Figure 12f.

Figure 12k.

Figure 12b.

Figure 12c.

Figure 12d.

Figure 12e.

Figure 12g.

Figure 12h.

Figure 12i.

Figure 12j.

Figure 12l.

Figure 12. Male patient unsatisfied with the smile (a); dentolabial view demonstrating changed gingival contour, presence of composite resin veneers and darkening of the tooth #11 (b); intraoral detail of the initial condition (c-d); after periodontal surgery a new diagnostic wax-up was performed focusing in the shape of the dental elements (e). The reduction guides and guide for preparation of the provisional were fabricated on the wax-up. Notice the vertical guide positioned on the dental element yet without reduction. Important information prior to reduction, given that there will be a small increase in volume and therefore, the wear shall not be too much invasive (f); peripheral delimitation with spherical diamond point (g); preparation of the orientation grooves (h); joining of the orientation grooves (i); preparation ended with subgingival extension of the tooth #11. Notice that the preparation of the tooth #11 is deeper because of the degree of darkening of the preparation of 21, which appears clear (j); evaluation of the preparation with the cervical guide (k-l); ceramic veneers of the teeth 15 and 25 cemented (m); Final smile (n); face in complete harmony (o); and naturalness (p).

254

Figure 12m.

Figure 12n.

Figure 12o.

255

Figure 12p.

256

Figure 13a.

Figure 13b.

Figure 13. Ceramic veneers of the same thickness but with different opacities (left side Emax HT®, Ivoclar Vivadent, Liechtenstein; and right side Emax LT®, Ivoclar Vivadent, Liechtenstein) on black background (a) and on white background(b).

257

The good color mimicry associated with conservative preparation shows relative biological cost/high aesthetic result, and there is no reason to choose for deeper preparations in cases where there is no need for masking the darkened background. Therefore, definitively, the establishment of a tooth bleaching protocol becomes fundamental, as described in section 5.3, to increase the value of the discolored teeth, to promote the desired conservatism, to homogenize the color of all substrates, to minimize the interference of the resin cement color in the process of determining the final result and create opportunities using thinner ceramic veneers. Proclination of the teeth Proclined teeth deserve a careful evaluation as to whether or not to reduce, and the mock-up turns into an excellent device towards design planning. Teeth with a slight proclination require the positioning of the mock-up to accurately determine the location of the reduction and allow for maximum preservation of dental structure. Small perforations in the mock-up reveal the exact location where the reduction should be carried out. Dental crowding is usually associated with proclination and therefore needs that the tooth reduction which was planned in the diagnostic wax-up and/or mock-up until the acrylic guide provided by the ceramist (Fig. 14a-d).

Figure 14a.

Figure 14b.

Figure 14c.

Figure 14d.

Figure 14. Initial smile revealing diastemas and presence of tooth 13 and rotated and buccally inclined, and the tooth 22 buccally inclined (a);intraoral detail of the buccally inclined teeth (b); observe the preparations confectioned in the teeth #13 and #22 (c); final smile (d)

258

The use of an acrylic guide made by the ceramist, as shown in Figure 15, is also an excellent choice for guiding the tooth preparation. Remember that both the mock-up as well as the acrylic guide are tools used from the final sight of the restorative dimension and are intended to minimize dental wear. The mock-up is neglected in cases of generalized proclination, it is impossible to install it in order to help the diagnostics and predict the aesthetic results without a previously prepared wax-up on a plaster model, removing unwanted morphological characteristics due to the establishment of the new rehabilitation. Therefore, an aesthetic rehabilitation planning performed digitally is a tool of great interest for the visual presentation of the case to the patient. Categorically, the abolition of the use of a mock-up is solely acceptable in this situation.

Figure 15a.

Figure 15b.

Figure 15c.

Figure 15d.

Figure 15e.

Figure 15f.

Figure 15g.

Figure 15h.

Figure 15i.

Figure 15. Initial smile (a); Initial intraoral aspect (b); preparation of the acrylic guide on the stone model to guide the reduction (c);positioning of the guide on the mouth (d); reduction with a diamond point with the acrylic guide positioned (e); appearance after reduction (f); final result after cementation of ceramic veneers of from #13 to #23 (g-h); and final smile (i).

259

Presence of restorations The presence of Class III, IV and V composite restorations in teeth undergoing ceramic veneers with preparation is common. According to Dunne & Millar,12 their maintenance in the preparation and the cementation of ceramic veneers can provoke several problems, such as microleakage, caries recurrence and fractures. However, there exist some situations where it is possible to maintain the composite restorations. Thus, it becomes necessary to find reliable clinical parameters that indicate the real possibility of maintaining these restorations. The maintenance or replacement of the composites depends on the location, extent and degree of aesthetic commitment of the remaining substrate.35 The interproximal extension comprises conventional or slice preparations. In the conventional preparation, the reduction is carried out in the interproximal area and prior to the contact point. This condition is indicated in teeth with presence of small and medium-sized proximal restorations. Slice preparations continue across the interproximal area and above the lingual surface, being indicated in teeth with the presence of large proximal restorations, diastema closure, discolored teeth, and in situations that require a change in the tooth width. (Fig. 16) According to Baratieri et al. (2002),2 the preparation of the proximal surface should be carried out so as not to allow the discolored tooth structure to be visible after cementation of the veneer. It is therefore very important to know the concept of static and dynamic areas of visibility. The static area consists of observing the patient and consequently the tooth to be veneerd frontally. Seen in this manner, the preparation or the restoration may always seem appropriate; however, when the observer searches the area of dynamic visibility, he realizes that the preparation is inadequate and that the proximal extension was insufficient, leaving a wide visible dark area on this surface. Whenever possible, the proximal contacts should be maintained in a natural tooth because they represent an anatomical feature which is very difficult to reproduce, prevent the movement of the teeth in the arch during the fabrication of the porcelain veneer, especially when provisional veneers are not used, facilitating the adjustment of the veneers, turning the bonding and finishing procedures simpler, as well as facilitating the control of bacterial plaque.2 In situations of complete involvement of both proximal surfaces of the dental element, straight or 45º terminations are recommended in the incisal portion, which favors the insertion of the veneer, being that the chamfer termination demands a greater volume of proximal reduction to enable the insertion of the piece in the incisocervical direction (Fig. 17). Therefore, the carrying out of full-crown preparations is indicated. Class V restorations should be considered as filling cores, instead of removing them entirely, because this would generate a considerable biological cost, whether it be by removing the tooth structure for the proper removal of the old restoration, or by removal of the tooth structure for preparation and elimination of peripheral retentions, especially along the upper cavity wall. What is imperative is the replacement of all of the old Class III and V restorations, by applying the acknowledged etching and bonding principles for composite restorations, inserting of shades (dentin) similar to the substrate and maintaining the mar260

Conventional

Slice

Figure 16.

Figure 17.

Figure 16. Teeth with the presence of small and medium-sized proximal restorations, require conventional interproximal area, in which the reduction is carried out in the interproximal area and anterior to the contact point (A). In teeth with large restorations, the interproximal preparation should be in the shape of a slice, whose wear involves the interproximal area and continues on the lingual surface with butt joint (B). Figure 17. Teeth with complete involvement of both proximal surfaces and straight incisal termination favor the insertion of the veneer (A); and teeth with complete involvement of both proximal surfaces and finishing beveled require a greater volume of proximal reduction, to allow for the insertion of the piece in an incisocervical sense (B).

gins always on the tooth, suitable for cementation of the ceramic on the tooth structure. Class IV restorations are always completely removed, as the ceramic will restore the lost portion of the tooth structure with impressive biomimetics and desired naturalness of the result. Diastemata The major concern in diastemata rehabilitation is the formation of black triangles and the inadequate manipulation of the gingival tissue. Thus, it is essential that the proper understanding of the formation of the black triangle is directly linked to the positioning of the contact point and that the misleading tooth preparation for installation of the ceramic veneer discourages the emergence profile.30 (Fig. 18) Gingival embrasures are ideally filled by the interdental papillae, but their presence or absence is directly correlated to the distance between the contact point and the bone crest.15,30 According to Tarnow,40 when there exists a distance greater than 5 mm between the bone ridge and the point of contact there will be a formation of the black triangle. Less than or equal to 5 mm between the contact point and the bone crest allows the formation of interdental papillae, hence, absence of the black triangle. 261

Figure 18.

Figure 18. Schematic drawing of the diastema between the central incisors with mesial walls converging to incisal (A); ceramic veneers cemented without preparation, which prevents the formation of an appropriate emergence profile and inadequate manipulation of the gingival tissue (B); ceramic veneers cemented with invasion of biological distances, artificial emergence profile and closure of the black triangle in an inadequate manner (C); and ceramic veneers cemented after subgingival preparation of the mesial surfaces, which enables the subgingival seating and therefore the creation of a contact point favorable for soft tissue manipulation and formation of the papilla.

262

The diastemata may be small and generalized, which allows for the performance of ceramic veneers without preparation (Fig. 3 and 4). In extensive diastemata, principally in central incisors, ceramic veneers must be performed with the objective of establishing a point of contact more cervical, establishing the conditions for the manipulation of gingival tissue and the formation of interdental papillae with triangular morphology. (Fig. 19) For this purpose the carrying out of a subgingival preparation is essential, which favors the ceramics fabrication, with respect to the precepts of the natural emergence profile, displacing the surface contact to the nearest region cervically26,27 the naturalness of the aesthetic result of the cemented ceramic veneers. What is imperative with such a subgingival preparation in areas of extensive diastemata where increased biological dimensions, as well as increased tissue volume are allowed and keratinized tissue present, which favors the subsequent subgingival cementation without loss of the naturalness or development of inflammatory processes. Further, this condition gives opportunity for tissue manipulation and proper conditioning, transforming the linear aspect of the papillae between the diastemata within morphologically triangular and the natural looking papillae. The evolution of techniques and materials related to ceramic veneers modified the dogmatic conventional fixed prosthesis preparations promoting convergence between involved walls and establishing the insertion axis through preparations or selective reduction whose conservative aim for maintaining a maximum of tooth structure, especially enamel, and the promotion of passive fit in the labial-palatal direction without the formation of mechanical stresses on the ceramics and naturalness in the result from the use of considerably translucent ceramics, with optical and chromatic features that mimic the missing or replaced dental structure.

Figure 19b.

Figure 19a.

Figure 19c.

Figure 19. Initial face (a); smile demonstrating the presence of defective composite resins, and diastemata (b); intraoral view reveals the presence of altered gingival contour and interincisal diastemata (c); after removal of the defective composite restorations, the subgingival preparation was carried out (d); observe detail from the model of the mesial surfaces and subgingival extension favoring the emergency profile (e); ceramic veneers cemented revealing favorable conditions for manipulation of the gingival tissue (f-g); final facial aspect (h-i).

263

Figure 19d.

Figure 19e.

Figure 19f.

Figure 19g.

Figure 19h.

264

Figure 19i.

265

2. Baratieri LN, et al. Odontologia restauradora: fundamentos e possibilidades. São Paulo: Santos; 2002.

REFERENCES

1. Almeida e Silva JS, Rolla JN, Edelhoff D, Araújo E, Baratieri LN. All-ceramic crowns and extended veneers in anterior dentition: a case report with critical discussion. Am J Esthet Dent. 2011;1:60-81.

3. Baratieri LN, Guimarães J. Laminados cerâmicos. In: Baratieri LN. Soluções clínicas: fundamentos e técnicas. Florianópolis: Ponto; 2008. p. 214-71. 4. Black GV. Management of enamel margins. Dent Cosmos. 1891;33:85-100.

5. Burke FJT. Survival rates for porcelain veneers with special reference to the effect of preparation in dentin: a literature review. J Esthet Restor Dent. 2012;24(4):257-65. 6. Calamia JR. Etched porcelain veneers: the current state of the art. Quintessence Int. 1985;16(1):5-12.

7. Cardoso PC, Decurcio RA, Almeida e Silva JS, Perillo MV, Baratieri LN. Noninvasive porcelain veneers: a comprehensive aesthetic approach. Am J Esthet Dent. 2012;2:238-54. 8. Christensen GJ. Longevity versus aesthetics: the great restorative debate. J Am Dent Assoc. 2007;138(7):1013-5. 9. Christensen GJ. The advantages of minimally invasive dentistry. J Am Dent Assoc. 2005;136(11):1563-5.

10. De Munck J, Van Landuyt K, Peumans M, Poitevin A, Lambrechts P, Braem M, et al. A Critical review of the durability of adhesion to tooth tissue: methods and results. J Dent Res. 2005;84(2):118-32.

11. Dietschi D, Spreafico R. Adhesive metal-free restorations: current concepts for the aesthetic treatment of posterior teeth. Chicago: Quintessence; 1999. 12. Dunne SM, Millar BJ. A longitudinal study of the clinical performance of porcelain veneers. Br Dent J. 1993;175(9):317-21. 13. Faunce FR, Myers DR. Veneer restoration of permanent incisors. J Am Dent Assoc. 1976;93:790-2. 14. Ferrari M, Patroni S, Balleri P. Measurement of enamel thickness in relation to reduction for etched veneers. Int J Periodontics Restorative Dent. 1992;12(5):407-13. 15. Fradeani M. Aesthetic analysis: a systematic approach to prosthetic treatment. Chicago: Quintessence; 2004. 16. Fradeani M. Six-year follow-up with Empress veneers. Int J Periodontics Restorative Dent. 1998;18:216-25. Fradeani M, Redemagni M, Corrado M. Porcelain laminate veneers: 6 to 12 years clinical evaluation: a retrospective study. Int J Periodontics Restorative Dent. 2005;25:9-17. 17. Freire A, Archegas LRP. Porcelain veneer veneer on a highly discoloured tooth: a case report. J Can Dent Assoc. 2010;76:a126. 18. Friedman MJ. A 15-year review of porcelain veneer failure: a clinician’s observations. Compend Contin Educ Dent. 1998;19:6258. 19. Gürel G. Porcelain laminate veneers: minimal tooth preparation by design. Dent Clin North Am. 2007;51(2):419-31, ix. 20. Gürel G. Predictable, precise and repeatable tooth preparation for porcelain veneers: practical procedures & aesthetic dentistry: PPAD. 2003;15(1):17-24. 21. Gurel G. The science and art of porcelain veneers. Berlin: Quintessence; 2003. 22. Hilgert LA, Lopes GC, Araújo E, Baratieri LN. Adhesive procedures in daily practice: essential aspects. Compend Contin Educ Dent. 2008;29(4):208-15; quiz 216, 218. 23. Hilgert, LA. Influência da coloração do substrato, espessura e translucidez da cerâmica na cor de facetas laminadas produzidas com o sistema CEREC inLab [tese]. Florianópolis, UFSC; 2009. 24. Horn HR. Porcelain laminate veneers bonded to etched enamel. Dent Clin North Am. 1983;27(4):671-84. 25. Kelly JR, Benetti P. Ceramic materials in dentistry: historical evolution and current practice. Aust Dent J. 2011;56(1):84-96. 26. Kelly JR. Dental ceramics: what is this stuff anyway? J Am Dent Assoc. 2008;139:4S-7S. 27. Layton DM, Clarke M, Walton TR. A systematic review and meta-analysis of the survival of feldspathic porcelain veneers over 5 and 10 years. Int J Prosthodont. 2012;25(6):590-6. 28. Lin T-M, Liu P-R, Ramp LC, Essig ME, Givan DA, Pan Y-H. Fracture resistance and marginal discrepancy of porcelain veneer veneers influenced by preparation design and restorative material in vitro. J Dent. 2012;40(3):202-9. 29. Magne P, Belser U. Estética dental natural: restaurações adesivas de porcelana na dentição anterior: uma abordagem biomimética. São Paulo: Santos; 2003. 30. Magne P, Hanna J, Magne M. The case for moderate “guided prep” indirect porcelain veneers in the anterior dentition: the pendulum of porcelain veneer preparations: from almost no-prep to over-prep to no-prep. Eur J Esthet Dent. 2013;8(3):376-88. 31. Magne P. et al. Clinical performance of novel-design porcelain veneers for the recovery of coronal volume and length. Int J Periodontics Restorative Dent. 2000;20:440-57. 32. Malament KA, Socransky SS. Survival of Dicor glass-ceramic dental restorations over 14 years. Part II: effect of thickness of Dicor material and design of tooth preparation. J Prosthet Dent. 1999;81(6):662-7. 33. Meyer Filho A, Vieira LCC, Baratieri LN, Lopes GC. Porcelain veneers as an alternative for the aesthetic treatment of stained anterior teeth: clinical report. Quintessence Int. 2005:191-6. 34. Peumans M, De Munck J, Fieuws S, Lambrechts P, Vanherle G, Van Meerbeek B. A prospective ten-year clinical trial of porcelain veneers. J Adhes Dent. 2004;6(1):65-76. 35. Raigrodski AJ. All-ceramic full-coverage restorations: concepts and guidelines for material selection. Pract Proced Aesthet Dent. 2005;17:249-56; quiz 258. 36. Rosenblum MA, Schulman A. A review of all-ceramic restorations. J Am Dent Assoc. 1997;128(3):297-307. 37. Sadowsky SJ. An overview of treatment considerations for aesthetic restorations: A review of the literature. J Prosthet Dent. 2006;96(6):433-42. 38. Calamia JR, Simonsen RJ. Tensile bond strengths of etched porcelain. J Dent Res. 1983;62:297, Abstract 1099. 39. Tarnow DP, Magner AW, Fletcher P. The effect of the distance from the contact point to the crest of bone on the presence or absence of the interproximal dental papilla. J Periodontol. 1992;63(12):995-6. 40. Terrey DA, Geller W. Odontologia estética e restauradora: seleção de materiais e técnicas. Chicago: Quintessence; 2014. 41. Terry DA. Natural aesthetic with composite resin. Mahwah, NJ: Montage Media; 2004. 42. White JM, Eakle WS. Rationale and treatment approach in minimally invasive dentistry. J Am Dent Assoc. 2000;131:13S-9S.

266

267

chapter 6.2

ceramic fragments Victor Clavijo | Andréa Melo | Cristiano Soares

most dental clinics. In contrast, the repairing treatment may have undesirable results if not properly indicated and planned. The expectation of the patient sometimes hinders the development of aesthetic cases, due to numerous clinical and biological limitations, which must be respected and properly explained. Knowing the articular disorders, as well as the masticatory forces, dietary habits and parafunctions is critical to the development of diagnosis and the correct indication of ceramic restorations. The longevity of conventional ceramic veneers comes from the possibility of bonding to the tooth,1 as well as the different characteristics of ceramic materials that are already largely known, namely: chemical resistance; biocompatibility; thermal expansion coefficient similar to that of tooth structure; high resistance to compression and abrasion;

INTRODUCTION

Currently, dental repairs that aim to redesign the beauty of the smile are routine in

adequate toughness, excellent reproduction of the optical properties of the tooth structure; radiopacity; bonding to luting agent and tooth substrate; and color stability according to works with clinical follow-up of up to 21 years.2-7 The maintenance of enamel is vital to the durability of ceramic veneers, so, the greater the amount of remaining enamel in the dental structure, the more favorable is the cementation and the smaller the deflection of tooth structure when subjected to masticatory forces, which prolongs the durability of the ceramic. So ceramic veneers are devoted as a safe and feasible alternative for restorations when cemented on enamel. The clinical success of conventional veneers, concurrently with the development of ceramic materials and the consolidation of the adhesion principles,2 combined with the minimally invasive philosophy culminated in the development of many types of adhesive restorations for reconstruction of the smile. Today the possibility of ceramic restorations to cover partially only the tooth surface stands out. Such restorations are called ceramic fragments, and the presentation of a

The cementation a ceramic restoration of the fragment type may be compared with bonding techniques involving tooth fragments after trauma. These techniques are under discussion since 1964, when Chosack & Eigdelman8 described an approach on fragment collage of the proper fractured dental element on a central incisor after injury. Since then, new studies with different techniques on the collage of fragments after tooth fractures have been reported. In 1990, Baratieri et al. indicated bonding of the tooth fragment itself as a treatment of choice when viable with satisfactory aesthetic results; maintenance of the anterior guide in enamel; and emotional and social recovery of the patient. The preparation of partial ceramic restorations cemented on enamel emerged following the same philosophy of bonding fragment on tooth remaining after injury without its reduction.9

270

LITERATURE REVIEW

clinical protocol for its implementation is the purpose of this chapter.

Kyrillos & Moreira presented a case report of partial restorations made of ceramic fragments and stressed the importance of thorough multidisciplinary planning for their longevity.10 The clinical step-by-step of the ceramic fragment technique on the incisal edge with minimal tooth reduction was described by Clavijo & cols.11 Following the philosophy of minimum reduction, the paper reports another case with multiple fragments for closure of diastemata, through partial restorations in the mesial and distal aspects without any tooth preparation. In 2011, the same authors described the ceramic fragments technique without tooth reduction.12 In the same period, Gresnigt & cols. reported a case with partial restorations associated with veneers with full coverage of the labial surface. At the time, the authors emphasized that the bonding, finishing and polishing steps are fundamental to the performance of the restoration.13 Horvath & cols. described another case report that used the technique of thin partial ceramics as a solution for class IV restoration of a maxillary incisor.14 The aim was to describe a minimally invasive method for indirect restorations. Tooth preparation was limited only to the removal of the old resin restoration. Thus, the margins of the ceramic remained in the middle third region. The rationale given by the author for using ceramics was greater color stability, less accumulation of plaque and higher mechanical strength. Antonio Signore & cols. described a technique for closing diastemata between central incisors using fragments without any tooth preparation, taking into account that the shape of both incisors made possible the insertion of the ceramic fragments. The authors underlined that in cases where no indication is given for tooth preparation are restricted and must be considered with caution.15 Andrade & cols. reported a follow-up, after a mean of five years, of six clinical cases. They were all fabricated with minimally invasive ceramic restorations and, after ce16

mentation, finishing and polishing procedures, they exhibited a ceramic-cement-enamel interface as usual. On that occasion the authors denominated this region of continuous adhesive area and concluded that the evaluation of the longevity of these interfaces throu-

WHAT ARE CERAMIC FRAGMENTS?

gh the study of micrographs is effective.

Ceramic fragments are ceramic restorations that cover partially one or more surfaces of the tooth.

271

cedure, which avoids unnecessary wear of the healthy tooth structure. These restorations, however, require higher degree of accuracy of the professional in the indication of the technique and their fabrication. There are four determining factors in choosing the method: 1. The shade of the tooth to be restored must be the desired, since fragments by their minimum thickness, are not able to block remnants that require color change. 2. By observing the space for the restoration one should only fabricate the fragments for cases in which replacement or augmentation of volume of tooth structure is required. 3. The insertion axis of the fragments must be evaluated to check whether or not removal in small undercuts is required. 4. The laboratory must master the manufacturing technique. These restorations are indicated in situations where the tooth position allows to add-up material, because even if minimal reduction is necessary, this should be started and

DETERMINING FACTORS FOR INDICATION OF CERAMIC FRAGMENTS

The ideal of ceramic fragment type of restorations is to be a minimally invasive pro-

finished in enamel. The maximum amount of viable enamel is thereby maintained in order to large deformation of the tooth structure not take place when subjected to masticatory forces.17 Similarly, optimization of adhesion occurs, since ceramic fragments are extremely fragile, without mechanical retentions and absence of resilience, depending therefore, of the adhesive and mechanical properties of healthy tooth enamel for increased longevity. So, they are indicated in situations as increasing of the incisal edge, increasing of the labial volume, closing or reducing diastemas, incisal fractures, restoration of the canine guidance, non-carious cervical lesions and even partial occlusal restorations for reestablishment of the occlusion after erosive or abrasive process with loss of tooth structure. In Table 1 it can be observed the main clinical indications, teeth usually involved and advantages when the ceramic fragment is a treatment option in the corresponding indications.

Table 1. Indications, involved tooth and clinical advantages of ceramic fragments.

INDICATIONS

.

TOOTH INVOLVED .

CLINICAL BENEFITS OF CERAMIC FRAGMENT

Anterior guidance recovery .

Maxillary and/or mandibular incisors . .

Greater stability of the material due to the potential mechanical resistance to wear

Canine guidance recovery

Canines

Longevity

Occlusal enamel recovery due to mechanical wear or erosion

Premolars and molars .

Cervical lesions - Class V .

Premolars and molars, possibly canines .

Diastema closure . .

Anterior and posterior teeth .

Class IV restoration .

Central and lateral incisors .

Color stability, ease of adjustments, less time of in-office service

Repair in ceramic restorations

Any restoration that has suffered minor fractures and have well adapted margins

Prevents removal of adapted restorations to prevent tooth grinding and allow greater biological conservation

272

Long term stability of the occlusion in restoration .

.

Ease of adherence of the gingival tissue due to increased smoothness of restoration .

Prevents tooth grinding required in conventional veneers which cover the entire labial surface and have cervical termination

WHEN ARE THE CERAMIC FRAGMENTS CONTRAINDICATED?

When there is no possibility of the insertion or there is inability to achieve the desired shape just by adding restorative material, fragments are contraindicated. In these two clinical situations, increased wear of tooth structure to redesign the smile becomes necessary. Additionally, in cases where there are severe occlusal dysfunctions, with loss of sound tooth structure, tooth fragments must not be used for restoration of the lost anatomy. Rehabilitation procedures are necessary in those cases involving other specialties, for the purpose of accurate diagnosis and treatment of occlusal disorders. Table 2 illustrates the main clinical situations when the prognosis for implementing ceramic fragments is not favorable.

Table 2. Unfavorable prognostic for executing ceramic fragments.

CLINICAL SITUATION

ABSOLUTE CONTRAINDICATION

Absence of insertion axis

X

Bonding area partially in dentin

X

Untreated occlusal dysfunctions

CLINICAL DIFFICULTIES

RELATIVE CONTRAINDICATION

X

Darkened substrate

X

Since this is a very sensitive technique, possible casualties may occur during the process. Table 3 describes the most common clinical intricacies during the manufacture of restorations such as ceramic fragments and their reasons.

Table 3. Clinical complexities for making ceramic fragments.

CLINICAL DIFFICULTY

REASON

Demarcate small areas of grinding .

Selective grinding should be performed so that the restoration is inserted passively

Absence of contact point .

Because it is inserted in a passive way, it is important to check the contact point prior to cementation

Fracture preliminary to cementation . .

When adjustments are needed, these should be carried out with the utmost caution as possible, as well as the pressure on the restoration during try-in and cementation

Poor positioning during cementation .

Since there is no defined end, a misguided insertion position is very common

Precision in the removal of overcontour after cementation

Como não há limitação de término, o laboratório deve enviar a restauração com sobrecontorno, que será removido após a cimentação

Inadequate polishing . Delayed fracture

Invariably, there is exposure of cement and removal of the glaze during the process The mechanical behavior of the fragments depends on the performance of the adhesive step

One way to minimize possible errors in the procedures is to establish clinical protocols and follow them without compromise. 273

SELECTING THE CASE It should verify the main complaint, the shade of the teeth and the possibility of additive planning. At this stage is very important that the clinician make intra and extraoral photographs as well as the initial impression taking with a polyvinilsiloxane (PVS) material, for obtaining molds and study models for diagnostic waxing.

TRIAL OF THE PLANNING Following the step of photographs,  with the initial models, the ceramist dental technician (CDT) shall perform the diagnostic wax. For better visualization of small shape changes, colored wax should be used on the stone model. The try-in procedure of the diagnostic wax in the mouth is called mock-up, which is fundamentally important in aesthetic treatments.18,19 Two purposes make the mock-up a necessary step in aesthetic treatments: to demonstrate a preview of the final work for approval by the patient and to guide small reductions to be performed.20 To perform the mock-up a silicone wall is used, which copies the waxed stone model to transfer the new shape obtained by the wax to the dental surface. A good wall should cover all the waxed teeth and at least one non waxed tooth on each side. With all arch subjected to waxing, the stability of the walls can be accomplished with small support in the palate. It is also indicated to use a high viscosity silicone, more rigid, relined with low viscosity silicone to copy every detail of the wax-up model. To better fit the wall the initial impression taking should be carried out with a PVS material. It is suggested to ask the technician to pour two models: one for waxing; and another for the patient to visualize differences after the wax-up. The material of choice for manufacturing the mock-up is a bis-acrylic resin, available in cartridges, which must be dispensed and mixed with a gun and an auto-mixing tip. This provides a more consistent polymer, without incorporation of air bubbles in the final mixture. The main features of this material which may be highlighted are: longer plastic phase; little release of heat during polymerization; low shrinkage; fine-grained particles; excellent polishing capacity; and low toxicity to the pulp.21-23 The silicone wall should be filled with resin and taken to the oral cavity. A slight finger pressure should be carried out on the cervical region of the wall in the first minute.After the 60-second period excesses may be removed. Each manufacturer has a specific time for initial setting. On average it is necessary to wait four minutes for wall removal. When the wall cutouts are performed accurately, merely polishing with felt disks needs to be done. Following completion of the process, one can visualize the desired shape. It can be seen in Tables 4 and 5 the specific materials and the check-list of the step as previously described.

274

Table 4. Materials required for manufacturing the mock-up.

MATERIALS REQUIRED FOR MANUFACTURING THE MOCK-UP 1

Wax-up model

2

High- and low-viscosity PVS material

3

#12D scalpel blade and scalpel handle

4

Gauze soaked in alcohol

5

Flowable composite, similar shade to bis-acrylic resin

6

Bis-acrylic resin

7

37% phosphoric acid (if it is necessary leaving the mock-up in the mouth for more than 1 week)

8

Adhesive

9

Disposable applicator (eg Microbrush®)

10

Felt disc for polishing

11

Ocher, brown, white and blue dyes

12

# 00 brush for applying the dye

13

Polywave LED light-curing unit

Table 5. Checklist for manufacturing the mock-up.

CHECK-LIST FOR MANUFACTURING THE MOCK-UP 1

Initial impression with PVS material

2

Make sure that the wax-up was additive

3

Preserve an initial model

4

Use colored wax for small changes

5

Do not isolate the model

6

Fabricate the wall, at least 4 hours before use

7

Fabricate the wall in high-viscosity silicone and reline with low-viscosity silicone

8 .

Make the cut of the wall as close as possible from the cervical (1 mm excess of the margin). Contour the interdental papillae

9

Maintain a minimum thickness of 4 mm from the wall in the buccal region

10

Perform prophylaxis of teeth with pumice and rubber cup

11

Dismiss 8.0 mm of the bis-acryl resin before placing the material on the wall

12 .

Start inserting the resin on the wall with the tip of the gun touching the incisal aspect. Incisocervical placement direction

13

Straight insertion of the wall in an unique direction

14

Wait for 1 minute by pressing the cervical region

15

Remove the excesses after 1 minute

16

Remove the wall with caution

17

Remove the uncured layer with alcohol

18

Characterize with dyes (optional)

19

Perform polishing with dry felt discs

SHADE SELECTION After defining the desired tooth shape through the mock-up based on the diagnostic wax, it is necessary to perform some procedures prior to the final impression taking. Accurate prophylaxis and removal of dental calculus must be performed, especially in the proximal and palatal area. If possible, this procedure should be performed in an earlier appointment for the impression because any potential gingival bleeding can impair the manufacturing of the mold. In jobs involving ceramic fragments, the tooth shade is crucial to the aesthetic performance after cementation. For this, the first impression appointment procedure is to perform the shade taking before any relevant tooth dehydration from the treatment.24 Then the necessary materials and check-list for performing the shade-taking can be observed (Tables 6 and 7). 275

Table 6. Materials required for shade taking.

MATERIALS REQUIRED FOR SHADE TAKING 1

Photographic camera

2

VitaClassical® shade guide and shade guide for bleached teeth

Table 7. Check-list for shade taking.

CHECK-LIST FOR SHADE TAKING 1

Make sure if the tooth is clean and free from calculus

2

After bleaching, wait for seven days for stabilization of color

3

Preferably, shade taking should be performed between 10am and 2pm. The photo shooting should be outermost containing lips and skin, for observation of the interaction of the assembly with light

4

Use the shade guide horizontally and in the same inclination of the tooth long axis, touching it

SELECTIVE PREPARATION When there is presence of retentive and sharp angles, minimal wear limited to the surface enamel is necessary.25 Visual inspection followed by demarcation with pencil of the undercuts in the tooth structure functions as a preparation guide for establishing the insertion axis of the ceramic restorations. Additionally, for some cases, the CDT can perform a small wear on the initial guide stone model, which will be inserted on enamel for removing undercuts.26-28 The grinding should be performed with a fine-grained diamond tip, followed by polishing with sandpaper discs. IMPRESSION TAKING For making indirect restorations, PVS is the choice between the impression materials (See Chapter 8). The superior clinical performance of this material is due to: tear resistance; low viscosity; dimensional stability; high capacity of elastic recovery; and the possibility of pouring twice. Obtaining a good antagonist stone model helps the accurate  occlusal adjustment. For this reason, a PVS should be used for molding both arches.29,30 Ideally, the two impression step must be used to obtain an accurate copy of tooth structure and gingival margin. However, the fundamental care should be retraction of the gingival margins for the impression.24 As a rule, when the retraction cord is inserted, retraction of the gingival margin takes place, which is suitable only for ceramics with cervico-vestibular termination. In the case of ceramic fragments, changing the cervical margin may produce overcontoured restorations. A final artificial appearance is thus obtained and, possibly, change of natural emergence profile. Ultimately, there may still be tissue inflammation and gingival recession. To avoid this, the ideal is always to perform the impression of fragments without retraction cord, keeping the gingival margin in the natural position. However, the use of retraction cord in the proximal surfaces is essential in cases of diastema or when you want to create a new emergency profile throughout the cervical extension. The materials required and the check-list for carrying out an accurate impression are described in Tables 8 and 9.. 276

Table 8. Materials required for impression taking.

MATERIALS REQUIRED FOR IMPRESSION TAKING 1

Retraction cords (#000, #00, #1) (eg, Ultrapack®, Ultradent, USA)

2

Packing instrument or composite spatula (eg Cosmedent® IPC-L or similar)

3

Hemostatic agent (eg Viscostat Clear®, Ultradent, USA)

4

High- and low-viscosity PVS impression material, gun dispenser, self-mixing and intraoral tips

5

Rigid metal trays (never use aluminum trays)

6

Gauze

Table 9. Check-list for impression taking.

CHECK-LIST FOR IMPRESSION TAKING 1 .

Make sure that the gingiva is healthy, so there is no bleeding. If deemed necessary, prescribe chlorhexidine mouthwash during the 15 days prior to impression

2 .

Make sure that there is space in the tray for the material; between the labial of the first molar and the tray there must have 8 mm for accommodation of the material

3 .

Choose the caliber of the retraction cord in accordance with periodontal biotype. The thinner biotype the thin is the cord

4 .

Apply the hemostatic agent and remove excess astringent with dry gauze prior to packing into the gingival sulcus. The thinner the spatula the better will be packing and lower pain sensation.

5 .

In the two- step impression technique, move the tray with the high viscosity silicone within the first 2 minutes after insertion into the mouth for creating spaces for the low-viscosity impression material

6

Remove the high-viscosity impression material, and the retraction cords

7

Dispense with the low viscosity material in the mouth and tray

SELECTION OF THE CERAMIC MATERIAL There are different materials for making fragment-type restorations. Dissilicate ceramics are indicated for occlusal and palatal restorations. These types of restorations can be produced by injection or CAD/CAM. On the other hand, the feldspathic ceramic must be sintered on a refractory stone model. The technique of preparation of this ceramic type is manual, performed by of powder and liquid increments. Injected or milled ceramics in small thicknesses are monochromatic and have many glass particles in its composition, making it more translucent in small thicknesses. Consequently, they have low value (degree of brightness), which can result in grayish look or translucent at best. When compared to disilicates, refractory ceramics show higher amount of feldspar and quartz in their composition. Additionally, they may be stratified since the first layer, and may receive a thin opaque ceramics, providing opaque or translucent areas even in small thicknesses. When fragments are manufactured to recover the canine guidance or the occlusal surface, it is interesting to use lithium disilicate due to increased toughness.31 It is worth mentioning the need for polishing after grinding ceramics which was previously adjusted in the mouth, since the high hardness of lithium disilicate combined with the high roughness of the restoration after occlusal adjustment can cause excessive wear of the opposing tooth.32 Table 10 shows the comparison of the major differences between ceramics. 277

Table 10. Characteristics of injection molded versus refractory ceramics.

INJECTED

REFRACTORY

Strength

380 MPa

90 MPa

Accept repairs

Yes

No

Light transmission

Lower

Higher

Cementation

Ease of manipulation

Dificuldade

Hardness

Higher

Lower

Costs

Lower

Higher

Time of fabrication

1/3

1

Adjustments of internal adaptation

Usual

Hard

TRY-IN OF THE RESTORATIONS The session should start with prophylaxis of the tooth structure with rubber cups or Robson brushes and pumice, is important to take special attention in the proximal areas, this is the point with greater accumulation of bacterial plaque. If there is calculus in the proximal region a proximal metal strip should be used to remove calculus, with smooth movements, avoiding cuts in the gingival region. Trying-in ceramic fragments is an extremely meticulous procedure that requires delicacy and rigorous care.33 The following guidelines should be followed. Observe the insertion axis: it is a great help to train the precise movement of insertion and correct positioning of the restoration in the stone model. To feel secure, the clinician repeats the movement to take the fragment on the natural tooth without performing pressure on the restoration. If any interference prevents the correct placement of the restoration, remove the perceived retention in the tooth, but never in the ceramic intaglio surface. In this way, fractures and cracks are avoided. Evaluate the point of contact: the adjustment process of the contact point is of extreme importance and fragility. It must therefore be precise and be carried out with the support of the restoration in hand or stone die.34 It is necessary that the professional have security in small movements that will be performed. There are resin cements with value and saturation options. These cement systems have try-in “cements”, which are glycerine gels, with coloration corresponding to the optical effects of the resin cement. The use of these proof or try-in pastes, as are commercially called can be made to correct small changes in value. This step should, however, be visualized with great care, because the restorations are extremely thin, and the shade used wrongly can be disastrous. Therefore, one should give preference to translucent shades of the cement. However, in bleached teeth can be used to tests high value try-in cement, whereas the bleached tooth has a higher value (brightness). CEMENTATION Choosing the luting agent Exclusively light-cured resin cements are of choice for cementation of fragment-type restorations.35 Relevant features deserving attention are: greater color stability; higher working time; and lower viscosity. With the great aesthetic demand and the evolution of materials for cementation it is possible to choose between light-curing cements based on a value scale rather than chroma, unlike other traditional light-curing cements, which, as 278

a rule, are based on the VitaClassical® shade guide (Vita, Germany) as color reference. In addition to the option working with different degrees of lightness (value), The exclusively light cured cements have alternative photoinitiators in their composition and, therefore, are more translucent and less yellowish. However, they should be polymerized with different wavelengths. In general, these cements are composed of alternative initiators such as lucerin, Bis Acyl Phosphine Oxide (BAPO) and Phenyl Propanedione (PPD). The lower viscosity facilitates the insertion of ultrafine restorations and prevents their fracture during the bonding step. Is worth noting that the curing of these cements should be performed by third-generation polywave-type LEDs, because they have different lamps with range between 385 nm and 515 nm, which ensures the reaction of alternative initiators such as lucerin, BAPO and PPD. Cautions for luting ceramic fragments Fragment-type ceramic restorations can be cemented off their proper seating. Because it is a mode that does not advocate conventional preparation of teeth, it has more than one insertion axis. To prevent the restorations being cemented wrongly, extreme caution during positioning and care in the removal of excess cement before polymerization is required. Professionals should also be positioned at different angles to view the restoration after insertion and prior to curing. It is recommended that the clinician place at 12, 3, 6 and 9 hours to check every angle of the restoration in the mouth before light-curing. In case of cementation of multiple restorations to be performed simultaneously. Whenever the centrals are involved, they should be the first to be placed to avoid errors in the region. Table 11 shows the materials required for cementation.

Table 11. Materials required for cementation.

MATERIALS REQUIRED FOR CEMENTATION 1

10% Hydrofluoric acid

2

37% Phosphoric acid

3

Pumice

4

Ultrasonic bath

5

Disposable applicatiors (eg Microbrush®)

6

ICB brush

7

#1 flat brush

8

Circular scalpel handle and # 12, #12D or #11 blades

9

PTFE tape

10

Dental floss

11

Proximal strip for composite resin polishing

12

Light-curing adhesive

13

Veneer type light-curing resin cement and try-in pastes

14

Silane

15

Ultrasound for tooth cleaning

16

Indented metal strips (Komet® or TDV®)

17

Hemostatic (Viscostat Clear®, Ultradent, USA), aluminum chloride type

18

Polywave-type curing light (eg BluePhase®, Ivoclar Vivadent, Liechtenstein)

279

Preparation of the ceramic restoration Hydrofluoric acid etching of ceramic fragments should be performed with caution because of their fragility. Importantly, etching should be performed after try-in of the restoration. Step by step for the preparation of the restoration 1. Application of 10% hydrofluoric acid on the internal area of the restoration: After the etching time, remove the acid in tap water with extreme caution so as not to fracture the restoration. Note that the etching time for each ceramic is different because of the amount of silica that each system has. The purpose of etching with hydrofluoric acid is exposing silica present in the spatial arrangement at the surface of the ceramic restoration. This available silica will be reactive to silane. Furthermore, it will create microporosities. Table 12 describes the etching time for each ceramic.

Table 12. Exposure time of ceramics to hydrofluoric acid.

FELDSPATHIC WITH LEUCITE (ON REFRACTORY)

LITHIUM DISILICATE (e.max®)

Hydrofluoric acid - 90 to 120 seconds

Hydrofluoric acid - 20 seconds

Contains apatite and leucite crystals

Microstructure 70% Li2Si2O5

Composition SiO2 50-65wt%

Spatial arrangement can be impaired due to excessive exposure to hydrofluoric acid Composition SiO2 57-80 wt%

After rinsing and drying a white, opaque surface will be obtained. At this moment, there is loosened silica of the structure and residues that must be removed with one of the following.36 2. Restoration cleansing: a new air/water spray for thorough rinsing of the restoration and removal of etching debris. 3. Silanization: the silane is applied to the etched surface and dried for at least 60 seconds. The application protocol of acid and silane varies between commercially available materials. Therefore, before using the cementation system, it is necessary be informed about the protocol recommended for each system. Preparation of the tooth structure 1. Prophylaxis with pumice and Robinson brush. 2. Packing of a #000 retraction cord mildly soaked in hemostatic (Viscostat Clear® , Ultradent, USA) (clear - aluminum chloride containing). Importantly remove excess hemostatic with gauze. 3. In the substrate, etching should be performed with 37% phosphoric acid for 30 seconds, in enamel, followed by rinsing with water jet and air drying. 4. The adhesive system is applied to the tooth surface which has been properly etched. After application of the adhesive system, excesses should be removed with the aid of a suction cannula and air jet is applied for evaporation of the solvent. 280

5. After seating the restoration on the tooth, the excess cement must be removed with the aid of brushes, dental floss and an indented metal strip. The initial curing for 3 seconds must be performed immediately after the previous phase. Note that removal with a brush before light curing aids in the formation of a line of continuous adhesion. As a result, there will be less bacterial colonization37 and there will be no gap formation from cement loosened with a explorer after initial polymerization.38 6. Removal of excess and application of glycerol to eliminate the inhibition layer and complete polymerization for 40 seconds on each side. 7. Removal of the cord and excesses with scalpel blade. FINISHING AND POLISHING Characteristics of the ceramic-tooth interface after cementation As mentioned, the overcontour of ceramic partial restorations should be removed after completion of the cementation step. Failure to remove excess ceramic can generate, in addition to the aesthetic compromising, food impaction, higher accumulation of plaque, difficulty of cleaning and consequent gingival inflammation. Poor polishing may lead to staining of the adhesive interface and bacterial adherence. Thus, one must remove the over-contour by means of finishing techniques and thorough polishing of the region throughout the restoration interface. Devoting the next appointment for the finishing and polishing step is recommended. When carrying out the grinding of the restoration, a part of enamel and glaze applied to the restoration is removed. These grindings are irreversible and therefore should be performed accurately and meticulously. The adhesive interfaces can be classified into vertical, horizontal and mixed.33 Vertical interface - It is characterized when the ceramic restoration has the largest area of the parallel interface to the long axis of the teeth (eg, closing diastema). Horizontal interface - In this case, the ceramic restoration has the largest area of the interface perpendicular to the long axis of the teeth (eg, correction of the incisal edge). Assemblies with mixed interfaces - When the ceramic restoration has perpendicular and parallel interfaces over tooth axis (eg, diastema closure associated with class IV type lesions). Finishing sequence at different interfaces At this stage, extra fine diamond burs are needed to finish at the termination of the restoration, which should be performed with movements perpendicular to the ceramic step. With this will be avoided the formation of depressions and undesired concavities. Precise movements and magnification are extremely important in this process. The finishing should be guided according to the classification of each interface.

281

Vertical interface - To perform the motion perpendicular to the interface with the step, it is necessary to tilt the head of the multiplier by 90°. Horizontal interface - Similarly, one should use the diamond tip perpendicular to the step. When carrying out finishing this type of interface you can find it difficult to insert or high speed or multiplier due to the position of the adjacent teeth, in which case it will be necessary to perform movements parallel to the step. With that the procedure becomes more risky. One should pay more attention to the motion of the diamond instrument, which must be in the ceramic-tooth direction. The grindings can be performed without irrigation with jets of air, to enable viewing the interface and prevent potential concavities. Mixed interfaces - There are situations where the edge of the ceramic restoration or even grinding the vertical or horizontal step creates a mixed interface, situation very common in canines, due to their larger volume in the middle third. When acting in mixed interfaces is indicated to divide the step line into segments and to apply the technique of the vertical and horizontal interface according to the position of each segment of the step. The diamond points should be fine, good origin and new. Ideally each bur should be used no more than 9 times, to maintain cut quality. Figures 1 and 2 can observe different cuts of diamond points subjected to scanning electron microscopy. As shown in the micrograph, thick grained burs should be avoided due to excessive cutting capacity, which would generate an extremely scratched surface. The interface finishing is considered complete when the fragment and the tooth structure are in continuity,16 without a step and properly polished. Clinically, a deep slope can be felt directly with the explorer. However, at the microscopic level can be observed small unevenness in the line of continuity between the ceramic, the luting material and enamel. Figure 3 shows the enamel surface after removal of the ceramic step. Note that, after finishing, the tooth-restoration assembly features grooves and partial removal of the ceramic glaze. In the pictures below (Fig. 4 and 5) it can be observed at higher magnifications the efficiency of finishing in the removal of the step formed in a vertical interface, immediately after cementation. Final polishing The goal of the polishing procedures is to reduce the surface roughness, making it less scratched gradually until the entire length becomes glossy. The greater surface smoothness leads to a brighter surface, which aids in the aesthetics. Moreover, it tends to decrease plaque adhesion and increase the longevity of the restoration. While it is important, it is noteworthy that the polishing with rubbers is unable to give back to initial smoothness of the restoration obtained with glaze of ceramics, which unfortunately had to be removed during the finishing process.39

282

Figure 1.

Figure 3.

Figure 2.

Figure 4.

Figure 5.

Figure 1. SEM micrograph of a new diamond tip under 81x magnification. Figure 2. SEM micrograph of diamond points of four different grits at 10X magnification. Figure 3. SEM micrograph of ceramic fragment and continuous adhesive line after finishing with extra-fine grit diamond point under 14x magnification. Figure 4. Scanning electron microscopy of the adhesive interface before finishing procedures. Note the angulation of the step immediately after cementation under 30x magnification. Figure 5. SEM micrograph immediately after finishing with extra fine diamond points. Notice the zero angulation in the adhesive interface, which proves the removal of the ceramic step. 30x magnification.

The quality of the polishing rubbers and their life time are of primary importance. With continued use, the diamond comes off of the their surface, reducing the polishing capacity and generating a surface with less smoothness and shine. Each rubber system has its respective order of granulation which should be followed according to the rules of each manufacturer. Next, Tables 12 and 13 which contain the necessary materials and the check-list for finishing.

283

Table 13. Materials required for finishing.

MATERIALS REQUIRED 1

Crayons or graffiti for demarcation of edges and reflection angles (fine tip)

2 .

Fine-grained conical-shaped, rounded end diamond points (2200F, 2135F and 2135FF)

3

Multiplier

4

FF diamond point, flame shaped, for palatal surface

5

Miniflex diamond discs for finishing of the incisal embrasures

6

Rubber kit for finishing and polishing of ceramics (Professor Victor Clavijo® bur set, Shofu, Japan)

7

Drawing compass

8

Contra-angle

9

Straight handpiece

Table 14. Check-list for finishing and polishing.

In the case of multiple teeth, make the finishing and polishing in another session

2

Use magnification whenever possible. Choose loupes with 3.5x increase on average

3

Check the necessary adjustments in multiple directions in 3, 9, 6 and 12 hour positions

4 .

To adjust the incisal edge, always make movement with the rubber on the lingual aspect by 45º, avoiding grinding the edge by buccal

5

Make sure that the occlusal contacts are balanced and there is no premature contacts

6 .

Make all movements with the bur in only one direction. Avoid going back and forth movements with the bur in rotation

7

As the mirror areas of homologous teeth need to be identical, check the size of the areas of reflection and light escape with the drawing compass.

A 34 year-old male patient, dentist, attended the clinic with aesthetic complaint from anterior superior segment due to the presence of composite resin restorations with color deficiency and shape. After clinical and radiographic examination, it was diagnosed that the restorations were with satisfactory adaptation, and the problem was solely aesthetic. Upon photographs and study models, it was possible to plan the removal of resins of the elements 13, 12, 11, 21, 22 and 23, together with the production of ceramic fragments in the mesial surfaces of elements 13, 12, 22 and 23. The clinical protocol carried out was

CLINICAL CASE

CHECK-LIST FOR FINISHING AND POLISHING 1

described in this chapter.

Figure 6.

Figure 7.

Figure 6. Initial photography. Patient displays unsatisfactory composite resin restorations on anterior teeth, necessitating replacement. Figure 7.Removal of the restorations with scalpel blades. Figure 8. After the conservative removal of fillings, the remaining enamel presents visually intact.

284

Figure 8.

Figure 9.

Figure 10.

Figure 11.

Figure 12.

Figure 13.

Figure 14.

Figure 15.

Figure 16.

Figures 9 and 10. A favorable geometry for the insertion axis of the ceramic fragments on the mesial surfaces of elements 13, 12, 22 and 23 is observed. Figure 11.Smoothing small sharp angles with sandpaper discs (Sof-Lex Pop-On®, 3M ESPE, USA). Figure 12. Small caliber retraction cords (#000, Ultrapack®, Ultradent, USA) in place to carry out a double cord technique in the proximal regions, to establish a new emergency profile. Figures 13 and 14. Retraction cords of larger caliber (#0, Ultrapack®, Ultradent, USA) in place to carry out the double cord technique in the proximal regions, in order to create a new emergency profile. Figure 15. Impression finalized by the double step technique and a vinyl polysiloxane material (Virtual®, Ivoclar Vivadent, Liechtenstein). Figure 16. Prepared stone model, sectioned for the fabrication of model of alveolar dies.

285

Figure 17.

Figure 18.

Figure 19.

Figure 20.

Figure 21.

Figure 22.

Figure 17.Refinement of dies to create taper for the fabrication of the alveolar model. Figure 18. Polishing of the dies to facilitate the adaptation on the alveolar model. Figure 19. Confection of notches in the dies to create an insertion axis. Figure 20. Sectioned dies for making the model. The “Alveolar Model” Technique. Figure 21. Dies in position on the impression. Note the fixation of dies with orthodontic wire and acrylic resin to maintain the correct position. Figure 22. Alveolar model finished.

286

Figure 23.

Figure 24.

Figure 25.

Figure 26.

Figure 27.

Figure 28.

Figure 29 a.

Figure 29 b.

Figure 23. Fitting of the dies in the alveolar model. Figure 24. Duplication of dies for making diagnostic wax-up, which will assist in the application of the dental ceramics. Figure 25. Preparation of diagnostic wax-up by addition. Figure 26. Finishing of the diagnostic wax-up by addition. Figures 27 and 28. Final result of the diagnostic wax-up by addition. Figure 29 a. Selected masses for layering of ceramic fragments. Figure 29 b. Model dies in refractory die and the first ceramic layer (IPS D.sign®, Ivoclar Vivadent, Liechtenstein), opalescent mass E1.

287

Figure 30.

Figure 31.

Figure 32.

Figure 33.

Figure 34.

Figure 35.

Figure 30. Ceramic sealing completed. Note the homogeneous and smooth layer, obtained through burning 70 ° C above the normal temperature. Figure 31. Stratification of the mesial aspect of the laterals. Mixture of opaque dentine masses DDA1 + DBL2 1:1. Mamellons, MMLight and Salmon. Incisal, TS2 and enamel E1 also involving the mesioincisal contour. Transition angles E2. In canines only the substitution of the ratio, 2:1.The focus of the application and choice of the masses is to mimic the healthy tooth remnant. Figure 32. After roughnening the entire ceramic surface one should define the reflection edges and make the necessary changes. Figure 33. Cautious smoothing of the angles. An important step which defines the long axis and the proper tooth dimension. Figure 34. After glazing manual polishing was performed. It is important that this step is accomplished prior to removal of the investment fragments. Figure 35. Polishing with brushes and diamond pastes.

288

Figure 36.

Figure 37.

Figure 38.

Figure 39.

Figure 40.

Figure 41.

Figure 42.

Figure 43.

Figure 36. Observe the delicacy of the fragments. Figure 37. Masses of ceramic correctly positioned. Proximal surfaces with sufficient opacity, labial surface with excellent effects of translucency and opalescence compatible with the tooth. Figure 38. Restorations placed on the alveolar model. Figure 39. Fragmentos ajustados no modelo sólido. Figures 40 and 41. Ceramic fragment in position on tooth #12. Figure 42. Fragments in position on the mesial surfaces of teeth 22 and 23. Figure 43. Dry try-in of the fragments with the sole purpose to check the fit.

289

Figure 44.

Figure 45.

Figure 46.

Figure 47.

Figure 48.

Figure 49.

Figure 50.

Figure 51.

Figure 52.

Figure 53.

Figure 54.

Figure 44. The fragment is hydrated simulating the use of clear or mean value cement. Figure 45. Wet try-in of the fragments for checking shade and shape. Figure 46. Try-in pastes (Variolink Veneer®, Ivoclar Vivadent, Liechtenstein) for increasing value. In sequence, mean value to high value +3. One can use small increases in value for bleached teeth. Figure 47. Final check of the contact points with carbon paper. Figure 48. Adjustment of the contact points with abrasive rubbers (Exacerapol®, Edenta, Switzerland). Figure 49. Plaque removal in the proximal surfaces with sandpaper strip. Figure 50. Prophylaxis of the region with pumice slurry. Figure 51. Packing of the cord retraction prior to cementation. Figure 52. Application of phosphoric acid at 37% for 30 seconds. Figure 53. Thorough rinsing with water. Figure 54. Application of the adhesive system.

290

Figure 55.

Figure 56.

Figure 59.

Figure 57.

Figure 60.

Figure 58.

Figure 61.

Figure 55. Ceramic rtching with 10% hydrochloric acid for 90 seconds. Figure 56. Thorough rinsing with water. Figure 57. After drying, there is a chalky layer related to the debris produced by etching. Figure 58. Removal of the residue with abundant rinsing water or air/water jets. Figure 59. It can be observed the removal of the chalky area. Figure 60. Application of a thin silane coating. Figure 61. Application of resin cement.

291

Figure 62.

Figure 63.

Figure 64.

Figure 65.

Figure 66.

Figure 67.

Figure 62. Insertion of the fragment with resin cement on the tooth structure. Figure 63. Removal of excesses with the brush technique. Figure 64. Light curing of the cement for 40 seconds on each surface (BluePhase®, Ivoclar Vivadent, Liechtenstein). Figure 65. Removing the retraction cords. Figure 66. Removing the interdental excesses with dental floss and a knot to create friction in the area, removing the excesses actively. Figure 67. Cementation completed without aggression to the periodontal tissues.

292

Figure 68.

Figure 69 a.

Figure 69 b.

Figure 70.

Figure 71.

Figure 72.

Figure 68. Start of finishing delimiting the edges and vertical interface. Figure 69 a. Removal of overcontour at the interface with extra-fine diamond point perpendicular to the long axis of the fragment. Figure 69 b. “Victor Clavijo” Polishing Kit (Ceramisté®, Shofu, Japan) Figures 70-72. Polishing of the interface with all of the rubber formats for dental ceramics (Kit “Victor Clavijo”, Ceramisté®, Shofu, Japan).

293

Figure 73.

Figure 74.

Figures 73 and 74. Observe the final result, which demonstrates the effectiveness of dental fragments technique.

294

REFERENCES

1. Albakry M, Guazzato M, Swain M. Facture Toughness, Microstructure And Toughening Me-chanism Of Leucite And Lithium Disilicate Glass Ceramics. Key Eng Mat. 2003;240-242:955-8. 2. Anami LC, Pereira CA, Guerra E, Assunção e Souza RO, Jorge AO, Bottino MA. Morphology And Bacterial Colonization Of Tooth/ Ceramic Restoration Interface After Different Cement Excess Removal Techniques. J Dent. 2012;40(9):742-9. 3. Andrade OS, Borges GA, Kyrillos M, Moreira M, Calicchio L, Correr–Sobrinho L. Area Of Adhesive Continuity: A New Concept For Bonded Ceramic Restorations. Quintessence Dent Technol. 2013;36:29-43. 4. Andrade OS, Romanini JC, Hirata R. Ultimate Ceramic Veneers: A Laboratory- Guided Ultra-conservative Preparation Concept For Maximum Enamel Preservation. Quintessence Dent Te-chnol. 2012;35:29-43. 5. Anusavice KJ. Phillips Materiais Dentários. 11A. Ed. Rio De Janeiro: Elsevier; 2005. 6. Baratieri LN, Monteiro S Jr, Caldeira de Andrada MA. Tooth Fracture Reattachment: Case Re-ports. Quintessence Int. 1990;21(4):261-70. 7. Buonocore M. A Simple Method Of Increasing The Colhesion Of Acrilic Filling Materials To Enamel Surface. J Dent Res. 1955;34:849-53. 8. Calamia Jr, Calamia CS. Porcelain Laminate Veneers: Reasons For 25 Years Of Success. Dent Clin North Am. 2007;51(2):399417. 9. Calamia Jr. Etched Porcelain Veneers: The Current State Of The Art. Compend Contin Educ Dent. 1998;19(6):625-8, 630, 632 Passim; Quiz 638. 10. Cardoso PC, Luz CA, Magalhães APR, Perillo MV, Monteiro LJE, Decurcio RA. Facetas Cerâmicas: Como Remover Os Excessos Do Cimento Resinoso? Clínica - Int J Braz Dent. 2013;9(3):252-8. 11. Chosack A, Eidelman, E. Rehabilitation Of A Fractured Incisor Using The Patient’s Natural Crown- Case Report. J Dent For Child. 1964;31(1):19-21. 12. Clavijo V, Calicho LE, Kyrillos M, Moreira M, Oliveira H. Visão Clínica: Fragmentos ce-râmicos: o estado da arte. Clínica - Int J Braz Dent. 2011;7(4):378-85. 13. Clavijo V, Kabbach W, Bocabella L. Restaurações Cerâmicas Com Mínimo Preparo Dental. Beleza Do Sorriso CIOSP 2013. 14. Clavijo V, Kabbach W. Fragmentos E Lentes De Contato: Detalhes Que Fazem A Diferen-ça: Treine Seus Olhos. Clínica - Int J Braz Dent. 2013;9(3):252-8. 15. Clavijo V, Kabbach W. Restaurações indiretas em cerâmica- Faceta sem preparo dental (lentes de contato). Clínica - Int J Braz Dent. 2012;8(4):374-85. 16. Clavijo VRC, Cavaretti MH, Beltrán MC, Ferreira LA, Andrade MF. Fragmentos cerâmi-cos. Clínica - Int J Braz Dent. 2010;6(3):290-9. 17. Duarte Jr S. Ceramic Reinforced Polymers: Overview of CAD/CAM Hybrid Restorative Materials. Quintessence Dent Technol. 2014;32-48. 18. Fradeani M, Redemagni M, Corrado M. Porcelain Laminate Veneers: 6- To 12-Year Clini-cal Evaluation. A Retrospective Study. Int J Periodont Restor Dent. 2005;25(1):9-17. 19. Friedman MJ. A 15-Year Review Of Porcelain Veneer Failure a Clinician’s Observations. Int J Prosthodont. 2007;20(4):389-96. 20. Gresnigt M, Mutlu Özcan. Aesthetic Rehabilitation Of Anterior Teeth With Porcelain Lami-nates And Sectional Veneers. J Can Dent Assoc. 2011;77:b143. 21. Gurel G, Sesma N, Calamita MA, Coachman C, Morimoto S. Influence Of Enamel Preser-vation On Failure Rates Of Porcelain Laminate Veneers. Int J Periodont Restor Dent. 2013;33(1):31-9. 22. Gürel G. Porcelain Laminate Veneers: Minimal Tooth Preparation By Design. Dent Clin North Am. 2007;51(2):419-31. 23. Gürel G. Predictable, precise, and repeatable tooth preparation for porcelain laminate vene-ers. Pract Proced Aesthet Dent. 2003;15(1):17-24, 26 24. Hill E. Dental Cements For Definitive Luting: A Review And Practical Clinical Considera-tions. Dent Clin North Am. 2007;51(3):64358. 25. Horvath S, Schulz CP. Minimally Invasive Restoration Of A Maxillary Central Incisor With A Partial Veneer. Eur J Esthet Dent. 2012;7(1):6-16. 26. Kurtzman GM, Strassler HE. Provisional Fixed Restorations. Dental Economics. 2006;3:1-12. 27. Kyrillos M, Moreira M. Sorriso Modelo: O Rosto Em Harmonia. São Paulo: Ed. Santos, 2004. 28. Layton DM, Walton TR. An Up To 16-Year Prospective Study Of 304 Porcelain Veneers. Quintessence Int. 1985;16(1):5-12. 29. Layton DM, Walton TR. The Up To 21-Year Clinical Outcome And Survival Of Feldspathic Porcelain Veneers: Accounting For Clustering. Int J Prosthodont. 2012;25(6): 604-12. 30. Lieu C, Nguyen TM, Payant L. In Vitro Comparison Of Peak Polymerization Temperatures Of 5 Provisional Restoration Resins. J Can Dent Assoc. 2001;67(1):36-9. 31. Magne M, Bazos P, Magne P. The alveolar cast. Quintessence Dent Technol. 2009;32:39-46. 32. Magne P, Belser U. Bonded porcelain restorations in the anterior dentition: a biomimetic approach. Chicago: Quintessence; 2002. 33. Magne P, Hanna J, Magne M. The Case For Moderate “Guided Prep” Indirect Porcelain Ve-neers In The Anterior Dentition. The Pendulum Of Porcelain Veneer Preparations: From Almost No-Prep To Over-Prep. Eur J Esthet Dent. 2013; 8(3):376-88. 34. Magne P, Magne M. Use Of Additive Waxup And Direct Intraoral Mock-Up For Enamel Preservation With Porcelain Laminate Veneers. Eur J Esthet Dent. 2006;1(1):10-9. 35. Magne P, Willian D. Additive contour of porcelain veneers: a key element in enamel pre-servation, adhesion, and aesthetics for aging dentition. J Adhes Dent. 1999;1(1):81-92. 36. Patterson CJ, Mclundie AC, Stirrups DR, Taylor WG. Refinishing Of Porcelain By Using A Refinishing Kit. J Prosthet Dent. 1991;65(3):383-8. 37. Perakis N, Belser UC, Magne P. Final Impressions: A Review Of Material Properties And Description Of A Current Technique. Int J Periodont Restor Dent. 2004;24(2):109-17. 38. Signore A, Kaitsas V, Tonoli A, Angiero F, Silvestrini-Biavati A, Benedicenti S. Sectional Porcelain Veneers For A Maxillary Midline Diastema Closure: A Case Report. Quintessence Int. 2013;44(3):201-6. 39. Strassler HE, Anolik C, Frey C. High-Strength, Aesthetic Provisional Restorations Using A Bis-Acryl Composite. Dent Today. 2007;26(11):128, 130-3.

295

chapter 7

ceramic systems Júnio S. Almeida e Silva | Juliana Nunes Rolla

related to the advent of new materials and techniques, but also linked to scientific evidence endorsing their use. The principle that guided the dental restorative therapies until now was strictly based on clinical performance, rather than the aesthetic quality inherent to the restorative material. Arguably with excellent clinical durability, gold alloy and amalgam restorations have been widely used both in the posterior as well as in anterior teeth, even though their appearance represented aesthetic discomfort to the patient.18 However, since the introduction of the first successful porcelain-fused-to-metal system,86 there is increasing demand for ceramic restorations because this is an aesthetic material with optimal properties due to the availability of a range of shades and translucency effects. Furthermore, historically, the aesthetics of ceramics had an inversely proportional relation to the mechanical properties and therefore, the first ceramic systems were necessarily fused to a metal infrastructure to increase the fracture resistance.73 However, this metal base could affect the aesthetics of the restoration by reducing the transmission of light through the ceramic, which may cause gingival darkening in the cervical region of the restoration, termed “the umbrella” effect”

4

(Fig. 1). This disadvantage, alied to increased aesthetic

requirements and the evolution of ceramic materials, led to a new era, which boosted the production of fully functional, durable and yet aesthetic ceramic restorations. Currently, when properly indicated, dental ceramics represent the restorative option with a better capaciity to reproduce the intricate optical effects of natural teeth, as well as to simulate and restore tooth rigidity, restablishing its biomechanical properties.59,60 The clinical performance of all-ceramic crowns and veneers have been successful and clinically tested.20,23,71,69,84,43,63,80 So when restoring anterior teeth, the modern all-ceramic systems are an excellent treatment option for fixed prostheses, crowns and veneers.59,20 However, treatment planning influenced by media, products not yet correctly tested, but commercially available, and the patients’ desire to satisfy their aesthetic demands have formed a dangerous combination with little regard to the analysis of risk-benefit of dental treatment.75 Indeed, the excessive application of ceramic veneers has been demonstrated and has probably been due to the development of reinforced ceramics, which led to a wider range of indications.Accordingly, traditional preparations designs for veneers have become extended designs driven by the defect of the tooth to be restored. These extended veneer preparations can be an alternative to crowns in the anterior dentition.84,16,17,19 Independent from the proven clinical success of all-ceramic veneers and crowns59,20 as well as any restorative procedure, from the moment they are cemented, the teeth are inserted into a restorative cycle.78,12 All-ceramic crowns have been extensively used in recent years due to longevity being comparable to PFM crowns, reaching impressive 98.8% clinical success rate after 11 years of service.59,20,13,20 The main causes of failures of these restorations involve catastrophic fractures, chipping of the veneering ceramics and secondary caries.59 Despite the fact that ceramic veneers when compared to crowns naturally involve a minimally invasive approach it is not clearly true that less tooth reduction by

298

INTRODUCTION

Restorative dentistry has undergone a revolution over the last thirty years not only

means of less invasive preparations will always result in an increased longevity of ceramic restorations. In this context, it was demonstrated that reinterventions without replacement of 36% of the teeth with ceramic veneers and retreatment with crown replacements of approximately 7% of cases occured after 10 years of clinical service.35,27 The main causes of failure of ceramic veneers are fracture, microleakage and cementation failure. This means that the ceramic veneers, especially if inaccurately indicated, are restorations more susceptible to future interventions than are ceramic crowns. Therefore, it is crucial that clinicians be aware of the correct indication of these restorations to provide them optimal longevity.12 Thus, neither the ceramic crowns or veneers should be the first choice in all cases, since several factors need to be considered in the preparation of treatment planning including previous ceramic restorations. In this chapter, a classification, according to the composition of dental ceramics is described. Yet, important considerations are addressed based on evidence related to the rehabilitation treatment planning in anterior teeth with crowns and ceramic veneers.

Porcelain-fused-to-metal

All-ceramic

Figure 1.

Figure 1. Schematic illustration of the effect “umbrella” in the gingival cervical region caused by improper relationship of metal with light.

299

Ceramic comprises any inorganic class of solid, non-metallic material that is subjected to high temperatures during its manufacturing. Ceramic is the oldest of the industries. It was born at a time when man began to use fire-hardened clay in making pots for storing water and food. This process of hardening obtained casually, has multiplied, evolved. Currently, in addition to its use as a constituent raw material for various household tools and civil construction, and as a plastic material in the hands of artists, ceramics are also used in high technology. Porcelain, a specific type of ceramic widely used for approximately 3

CERAMICS

The term “ceramic” is derived from the Greek, Keramos, meaning “burned matter”.

thousand years, is a blend composed of three minerals: white clay (calium), quartz and feldspar. When these three ingredients are pulverized, mixed, molded and fired, they become the white ceramic known due to staining acquired after the firing process. Porcelain is a type of white ceramic which possesses a relatively high strength and translucency. White ceramics comprise a wide range of products such as cutlery and porcelains (utilitarian and decorative), sanitary, technical porcelain and for dental use, which differ, among other factors, by the firing temperature, composition of the mass and the type of melting.34,50 There are different types of ceramics for dental application as well as different classification systems and indications. In this chapter, the current ceramic systems are ordered according to their main composition. Dental ceramics may be divided into vitreous, parti-

In 1962, Weinstein & cols.86 found that, by heating a certain type of feldspar rock containing 11% potassium and rapid cooling, to form a glass. This glass, when reheated, had a high coefficient of thermal expansion, because of the formation of a new crystal, leucite. By developing this crystal, they discovered the first particle to reinforce modern ceramics and, even more importantly, achieved through the incorporation of leucite crystals in feldspathic ceramics, a novel ceramic, which possesses a similar thermal expansion coefficient similar to that of metal. And so the first successful porcelain-fused-to-metal restorations were successfully made. Feldspathic ceramics is essentially a mixture of potassium feldspar (K2O.Al2O3. 6SiO2) or sodium feldspar (Na2O.Al2O3.6SiO2) and quartz (SiO2). These components are heated at high temperatures (1,200 ºC to 1,250 ºC), and the incongruent fusion of feldspar leads to the formation of a liquid glass of leucite crystals (K2O.Al2O3.4SiO2). The molten mass is abruptly cooled to maintain the glassy state, which is basically constituted by a network of silica. After cooling, the mass is ground, and a powder is obtained. The feldspar ceramic contains two phases: one glassy, responsible for the translucency of the material, and the other crystalline, which confers resistance. Land57 introduced the ceramic crowns in 1903, but the material was not very resistant, the fabrication technique was complicated, and the choice of cementation agents, restricted. Although they were chemically stable materials and provide excellent aesthetics, they are essentially brittle materials. The compressive strength of these materials is high (350 to 450 MPa), but their tensile strength is very low (20 to 60 MPa), which is typical of fragile materials. 300

GLASS CERAMICS

cle-reinforced and polycrystalline.50

The inherently low tensile strength restricted their use to low loading situations of stress in the anterior region (Fig. 2).85 Ceramics, being primarily a glass, does not present any fracture strength. Minute cracks on the material surface act as initiation sites for catastrophic failure. Because it is a brittle material, ie, presenting restricted ability for dissipate localized stresses, which are concentrated at the edge of the cracks and thus promote their propagation through the ceramic and consequently, the fracture of the material without the presence of plastic deformation. Knowing that the ceramic material fracture process is associated with the propagation of cracks in the material, whatever that might hinder or prevent propagation will increase the intrinsic strength of the ceramics.85 For this purpose, filler particles began to be added to the glass-ceramics, to improve properties such as strength as well as thermal expansion coefficient. Highly aesthetic ceramics are predominantly vitreous. They are the best materials for reproducing the optical properties of enamel and dentin, and are often identified as veneering porcelain, which often are accompanied by a ceramic infrastructure (polycrystalline or glass particle-reinforced) more suitable when jointly used.

Figure 2.

Figure 2. Example of feldspathic ceramics (Creation CC) being applied over refractory die for the manufacturing of a conventional veneer on tooth 21.

301

In order to improve mechanical properties such as strength, thermal expansion and contraction, manufacturers have added particles to the basic composition of the glass-ceramics. These particles are generally crystalline, but may also be high-melting glass particles, which are stable at ceramic firing temperatures.49 Greater amount of leucite was added to the feldspathic ceramic in order to increase its resistance. Approximately 55%wt of leucite crystals were added to a glass matrix, which brings advantages such as the absence of an opaque infrastructure, good translucency and the possibility of being used without special laboratory equipment, since the technique for manufacturing these ceramics is similar to that for feldspathic ceramics.49-51 Currently, the main and most widespread product for leucite-reinforced ceramic restorations is the injection system IPS Empress Esthetic and IPS Empress CAD (Ivoclar Vivadent, Liechtenstein) (Fig. 3 and 4). LITHIUM DISILICATE PARTICLE-REINFORCED IPS Empress 2 (Ivoclar Vivadent, Liechtenstein) is a lithium disilicate reinforced ceramic (SiO2-Li2O), which is manufactured by combining the techniques of lost wax, and heat and pressure injection. A ceramic block of the desired color is plasticized at 920 °C and injected into an investment ring under pressure and vacuum. IPS Empress 2 improved the flexural strength three times over IPS Empress and may be used for three-element fixed bridges in the anterior segment, until the second premolar. The infrastructure is layered with a fluorapatite-based veneering porcelain (IPS Eris, Ivoclar Vivadent, Liechtenstein), resulting in a semi-translucent restoration with optimized light transmission. In 2005, the IPS e.max Press system (Ivoclar Vivadent, Liechtenstein) had been launched, consisting of a lithium disilicate-based pressable ceramic superior than IPS Empress 2. Due to a difference in the firing process, both the physical properties as well as its translucency were improved, making it also feasible to be utilized as an aesthetic veneering ceramic. The IPS e.max system is available for injection as well as CAD/CAM technologies (Fig. 5 and 6). Two types of ingots are available for the injection technology: IPS e.max Press, a lithium disilicate-reinforced ceramic and IPS e.max ZirPress, a lithium disilicate glass reinforced ceramic for application over zirconia copings. For veneering, the IPS e.max Ceram layering ceramic was developed, a novel type of ceramic, which has a crystalline phase composed of nano- and micro-fluorapatite crystals.This may be applied over all IPS e.max products.59,20,51 Generally, they are reinforcing particles which are dissolved during etching, creating micromechanical retention to allow their adhesion to dental tissue through the use of adhesives and resin cements. These particles may be mechanically added during manufacturing as a powder or by precipitation inside the glass matrix, through special nucleation and temperature increase processes.51

302

REINFORCED CERAMICS

PARTICLE-REINFORCEMENT

Figure 3.

Figure 4.

Figure 5.

Figure 6.

Figure 3. Ceramic ingots reinforced with approximately 55% of leucite crystals. IPS Empress ingots (Ivoclar Vivadent). Figure 4. CAD/CAM ceramic block reinforced with approximately 55% of leucite crystals, IPS Empress CAD (Ivoclar Vivadent). Figure 5. CAD/CAM ceramic block reinforced with lithium disilicate crystals, IPS e.max CAD (Ivoclar Vivadent). Figure 6. Ceramic ingots reinforced with lithium disilicate crystals. IPS e.max Press ingots (Ivoclar Vivadent).

(GLASS INFILTRATED) ALUMINA-, MAGNESIUM- AND ZIRCONIA-REINFORCED In-Ceram Alumina (VITA Zahnfabrik, Germany), introduced in 1989, was the first all-ceramic system designed for single restorations and anterior three-element fixed bridges. In this system a highly resistant ceramic core manufactured by the “slip casting” technique, which serves as the infrastructure. This provides flexural strength of 400 MPa and a marginal discrepancy of 40 µm. The infrastructure is fabricated from a dense alumina paste (70% to 80% vol.), which is applied on the stone die, carried to the furnace where alumina sintering occurs at 1,120 ° C for 10 hours. This produces a scaffold of alumina particles, which is infiltrated by glass in a second firing, at 1,100 ° C for 4 hours to remove porosity, increasing the strength and limit the potential for crack propagation. Feldspathic porcelain is applied over the infrastructure (Vitadur Alpha, Germany), since the high percent of alumina makes the infrastructure very opaque. Alumina blanks (Vitablocks In-Ceram Alumina, Vita, Germany) are also available for computerized (CAD/CAM) application in combination with Cerec (Sirona, Germany).25,13,14,62 303

In 1994, In-Ceram Spinell (Vita, Germany) was introduced as an alternative to in-Ceram® alumina opaque core. It contains a mixture of alumina and magnesia (MgAl2O4) within its structure, making it translucent. However, its flexural strength is 25% lower in relation to in-Ceram alumina, and therefore the cores are recommended only for anterior crowns. This material may also be made with Cerec Inlab, to be followed by veneering with a feldspathic porcelain. In-Ceram Zirconia is also a modification of the original in-Ceram Alumina system, with the addition of 35% zirconium oxide.7 A flexural strength of 750 MPa (approximately 20% more than in-Ceram Alumina) allowing for the production of posterior total crowns and three element fixed bridges, including the posterior areas on natural teeth or implants. The traditional technique of “slip casting” may be used, or the core may be obtained by partially sintered, prefabricated blocks, associated with a mechanized system

These ceramics are exclusively produced by CAD/CAM technology and designed for the production of structures in polylytic restorations, without a glass matrix in their compositions. All of their atoms are condensed under regular arrangements, which makes exceedingly this class of material more resistant to the propagation of flaws than glass-ceramics or those containing a vitreous content in their composition.49,51 HIGH ALUMINA CONTENT A natural evolution of alumina-reinforced systems considered the possibility of developing a pure alumina structure. There are at least two systems on the market that offer pure alumina structures, Procera AllCeram (Nobel Biocare, Sweden) and InCeram AL system. The main advantages are increased strength and superior light transmission when compared to glass-infiltrated materials. Procera AllCeram was developed by Andersson & Oden3, with copings containing 99.9% alumina, which provides an average flexural strength of 650 MPa and marginal discrepancy below 70 µm. Combined with a low fusion ceramics, the Procera system exhibits the highest strength among the alumina-based materials, and less in comparison merely to those that are zirconia-based. This exclusively uses CAD/CAM technology for building infrastructures and well suited for fabricating frameworks of anterior and posterior full crowns, three-element fixed bridges for anterior and posterior region.59,44 The coping of this ceramic is produced by a special process, which involves sintering of 99.5% pure alumina from 1,600 to 1,700 °C, which is highly densified. This is then sent to the laboratory for manufacturing the aesthetic portion of the crown, using feldspathic glass, made compatible through the technique of natural stratification.59 Alumina copings for full crowns must have 0.6 mm thickness for posterior teeth and 0.4 mm for anterior teeth. In the case of fixed prostheses, the area of the connector between the bridge abutment and pontic must be 4 mm high and 3 mm wide. One of the difficulties in glass-infiltrated and high alumina-content systems is that they do not allow for etching of the ceramic surface to improve retention. Being that the fitting surface is 304

POLYCRYSTALLINE CERAMICS

and then veneered with a ceramic feldspathic.59,7

made of alumina, rather than silica, there are not any bonding agent available which can effectively join ceramic structure to the resin cement. Without an effective bonding agent, or an ideally micromechanically retentive surface, these systems may not be bonded to the dental tissues with resins and thus are lacking all the benefits associated with ceramic restorations using adhesive resin cements.57 HIGH ZIRCONIA CONTENT Zirconia is a polymorphous material existing in three forms. At its melting point (2,680 ºC), the existing cubic structure transforms into a tetragonal phase (2,370 ºC).3,40 The other transformation occurs at about 1,170 ° C and is accompanied by a volumetric expansion of approximately 3-5%, which causes high internal stress. Yttrium Oxide (Y2O3) is added to the pure zirconia for controling the volumetric expansion and stabilizing the material in the tetragonal phase at room temperature. The stabilization of the mechanical properties of zirconia, such as its chemical and dimensional stability, and high mechanical strength, is of interest for the restorative dentistry, especially when subjected to excessive loads on the surface, some crystals stabilized in tetragonal form may metastasize back to the monoclinic form, with an approximate increase of 4-5% vol., by acting like a sealant, creating a localized “weld”, which prevents the propagation of failures more internally. This particular phenomenon of zirconia is named toughening transformation41 (Fig. 7).

Figure 7.

Figure 7.CAD/CAM polycrystalline ceramic blocks with high zirconia content (inCoris ZI, Sirona).

305

The manufacturing process for machining zirconia structures may be performed through two manufacturing strategies. Depending on the system, both densely sintered zirconia blocks as well as semi-sintered blanks may be machined. Densely sintered zirconia blocks are machined in the actual size of the structures. However, the high hardness and friability of these blocks have certain disadvantages such as extended periods for machining and an increased wear on the parts of the milling unit; and further, when using these blocks, the machining of the thin parts of a structure is a difficult process.41,70 Semi-sintered blanks, on the other hand, are available in a semi-porous state and have “chalky” consistency, being easier to be machined by the milling unit; thus causing less cohesive fractures of the zirconia structures and less wear.40 However, after the machining of the semi-sintered blanks, the structures must then be sintered in order to achieve its final density and the maximal mechanical properties of the zirconia. This sintering process is characterized by a high sintering shrinkage of about 20% to 30%, which must be compensated for during the machining procedures as well as the sintering shrinkage creates an additional challenge for the software, which is responsible for the accurate calculation of a structure which is 20% to 30% larger than its actual dimensions after sintering. Accordingly, the structure will contract precisely to the desired final dimension after the sintering process.40,41 Despite the trend of milling fully sintered blocks to promote better dimensional accuracy, CAD softwares have been effective in compensating for the sintering shrinkage of zirconia.40,41,58 75,51 The Procera AllZirkon system (Nobel Biocare) contains a high zirconia content and a flexural strength of 1,200 MPa. It is indicated for the fabrication of infrastructures for anterior and posterior crowns, with application of a veneering feldspathic ceramic with compatible thermal expansion coefficient. The laboratory phase is similar to Procera Allceram.75 The Cercon Zirconia system (Dentsply-Degussa) is indicated for the production of copings for anterior and posterior full crowns, as wellas infrastructures of three- and four-element FPDs of the anterior and posterior regions. The material is supplied in the form of semisintered ceramic blanks. In this system the infrastructure is constructed in wax and scanned with the laser unit of the Cercon system. The ceramic block is milled on a specific CAM unit of the system and then sintered to a compact form at 1,350 °C for 6 hours. Low fusion veneering ceramic is applied over the infrastructure (CerconCeram), with a coefficient of thermal expansion compatible for application over zirconia.59 The Lava system (3M ESPE, USA) uses a zirconia infrastructure with a high flexural strength, high fracture toughness and high modulus of elasticity when compared to alumina. The stone model is scanned by an optical process, LavaDesign software is used to design the structure, which is then fabricated using semi-sintered blocks. The restorations may be colored with up to seven colors and then undergo sintering for 8 hours. Figures 8 and 9, adapted from Della Bona & Kelly,23 show the main commercially available ceramic systems for all-ceramic restorations, based on the matrix composition, concentration and type of filler particles, manufacturing process and brand name.

306

MATRIX

FILLER

PROCESSING

BRAND NAME

1. GLASS-CERAMICS 1.1 Aluminum-silicate glass (feldspar or synthetic)

High melting glass, nepheline, albite (approx. 40%)

2. REINFORCED CERAMICS 2.1 Particle-reinforced glass, high content of glass

leucite (40% - 50%)

lithium disilicate (70%) 2.2 Low glass content (particlereinforced glass)

CEREC or InLab

Mark II1

CEREC/InLab

EmpressCAD2

pressed

Empress Esthetic2 OPC3

powder

Optec3 Cerinate4 Mirage5

CEREC/InLab

e.max CAD2

pressed

e.max Press2

InLab alumina, spinel, alumina/zirconia (70%)

or Dental Lab

Triluxe1 Triluxe1 Forte1

In-Ceram alumina1 In-Ceram spinel1 In-Ceram zircônia1

3. POLYCRYSTALLINE CERAMICS Dopping* 3.1 Alumina

Mg 93%) grain growth control

InLab

In-Ceram AL1

CAD/CAM

Procera6

3.2 Zirconio

Y, Ce, Al (3% to 5%) increased transformation toughness

InLab

In-Ceram YZ1 e.max ZirCAD2

CAD/CAM

Lava7, Cercon8, Procera6

Figure 8.

MATRIZ

FILLER

PROCESSING

BRAND NAME

1. GLASS-CERAMICS 1.1 Veneering

Dies, opaquers (4% to 5%)

1.1 Press-on zirconia

Leucite moderately modified, chemical dopants (5% to 10%)

1.1 Press-on metal

powder

Vita VM7

powder

Vita VM9 IPS e.maxCeram

Injection-molded

IPS e.maxZirPress

powder

Vita VM13, 15 IPS Inline

Injection-molded

IPS InLine POM Vita PM9

Leucite (17% to 25%)

Figure 9.

Figure 8. Organizational chart of commercially available dental ceramics for all-ceramic restorations, based on the matrix composition, concentration and type of filler, the manufacturing process and trade name. For polycrystalline ceramics not containing glass (3), the main phase (“matrix”) is alumina or zirconia, and “loads” are not particles; are modified atoms called “dopants or stabilizers.” Cerec, chairside, and inLab, for the dental technician, are types of CAD/CAM systems. Superscript numbers refer to the manufacturers: 1-Vita Zahnfabrik; 2-Ivoclar Vivadent; 3-Pentron; 4-Den-Mat; 5-Chameleon Dental Products; 6-Nobel Biocare; and 7-Dentsply Prosthetics. Figure 9. Organizational chart of commercially available dental glass ceramics for veneering of all-ceramic restorations, based on the matrix composition, concentration and type of filler, the manufacturing process and trade name.

307

sent other recommendations concerning the directions of current ceramic systems. Ceramics with a high glass content, such as feldspar, are indicated for veneers of anterior teeth, such as ceramic veneering as well as for partial restorations in posterior teeth with restrictions, because these restorative materials do not exhibit the guaranteed sufficient strength to withstand mechanical stresses without the support of the remaining tooth structure,69 which for single crowns, restricts their use for veneering copings which are fabricated from tough infrastructure ceramics. Leucite-reinforced ceramics are indicated for veneers, veneering ceramics and partial restorations of the posterior teeth.59,41 Ceramics based on lithium disilicate are recommended for single crowns and three-element fixed bridges in anterior teeth as well as for posterior partial restorations.45,58,36,37,65,39,55,79,53,42 Alumina-reinforced (glass infiltrated) ceramics may be indicated for single crowns and fixed bridges, with exception of In-Ceram Spinell, whose application is recommended only for anterior teeth.75 Zirconia-reinforced (glass infiltrated) ceramics function well on single crowns and three- element fixed bridges in the anterior segment. For the molar region, evidence suggests that only polycrystalline ceramic systems are indicated, since zirconia and alumina have superior mechanical properties as an infrastructure material and may also be used in implant abutments and implant-supported restorations.59,51 The successful application of ceramic systems depends on the clinician’s ability to properly select the material with respect to their mechanical properties, aesthetics and cementation. From the perspective of surface treatment for cementation, ceramics may be divided into etchable (sensitive to attack from hydrofluoric acid) and non etchable (resistant to etching with hydrofluoric acid). The optimization of clinical behavior, of etchable ceramics combined with adhesive cementation is advisable.49,50,51 Etchable (silica-based) ceramics are more aesthetic, translucent and have lower fracture resistance when compared to non etchable ceramics (rich in metal oxides).33 Figures 10 and 11 are adaptations from the tables demonstrated by Hilgert et al.,45 organize the main ceramic systems according to the type of surface treatment required for cementation. Ceramics that contain high amounts of metal oxides (> 85%), such as alumina or zirconia, are not sensitive to hydrofluoric acid, nor are their surfaces rich in silica. Thus, the adhesive cementation through etching and silanization does not generate acceptable results. Non etchable ceramics are mainly characterized by their high strength compared to silica-based ceramics, as a result, the indication for ceramic materials not sensitive to hydrofluoric acid is for the preparation of infrastructures of crowns and fixed bridges, which will be veneered by feldspathic and glass-ceramics. The high strength allows that the ceramic for infrastructures not to depend on the support given by the dental substrate via adhesive bonding, to resist the occlusal efforts. This means that by the existence of a preparation geometry favorable to macromechanical retention, is possible to perform cementation by the conventional technique.75 If there is a need or professional preference for the adhesive cementation in non-etchable all-ceramic restorations, It is necessary to treat the internal surface of the restorations in order to promote surface irregularities, as hydrofluoric acid promotes as a surface treatment of etchable ceramics. Accordingly, some surface treatment techniques have been deemed to be satisfactory: silica coating 308

GENERAL CLINICAL RECCOMENDATIONS

Independent of the indications suggested by the manufacturers, clinical studies pre-

CERAMIC SYSTEMS

INDICATIONS

CHARACTERISTICS

IPS Empress (Ivoclar Vivadent)

lnlays, Onlays, Overlays, Crowns, Veneers

Leucite-reinforced glass ceramics Injection processing under heat and pressure Fracture strength = 160MPa

IPS Empress CAD (Ivoclar Vivadent)

lnlays, Onlays, Overlays, Crowns, Veneers

Leucite-reinforced glass ceramics CAD/CAM Processing Fracture strength = 16DMPa

VITABLOCS (VITA)

lnlays, Onlays, Overlays, Crowns, Veneers

Feldspathic ceramics. CAD/CAM Processing Fracture strength = 15DMPa

E-Max (Ivoclar Vivadent)

Crowns and Veneers (Anatomical restorations or copings). Infrastructure for anterior fixed bridges of up to three elements.

Lithium disilicate-reinforced glass-ceramics Injection processing under heat and pressure Fracture strength = 36DMPa

E-Max CAD (Ivoclar Vivadent)

Crowns and Veneers (Anatomical restorations or copings). Infrastructure for anterior fixed bridges of up to three elements.

Lithium disilicate-reinforced glass-ceramics CAD/CAM Processing Fracture strength = 36DMPa

Feldspathic Ceramics

Veneers, lnlays and Onlays with restrictions due to low resistance

Restorations made by the refractory die technique Fracture strength = 90 to 1 00MPa

CERAMIC SYSTEMS

INDICATIONS

CHARACTERISTICS

InCeram Spinell (VITA)

Copings of Anterior Crowns

Processing by slip casting or CAD / CAM followed by glass infiltration Fracture strength = 4DDMPa

InCeram Alumina (VITA)

Copings of anterior and posterior crowns; infrastructure of anterior and posterior fixed bridges of up to three elements

Processing by slip casting or CAD / CAM followed by glass infiltration Fracture strength = 5DDMPa

InCeram AL (VITA)

Copings of anterior and posterior crowns; infrastructure of anterior and posterior fixed bridges of up to three elements

Densely sintered CAD / CAM processing Fracture strength >5DDMPa

InCeram Zirconia (VITA)

Copings of anterior and posterior crowns; infrastructure of anterior and posterior fixed bridges of up to three elements

Processing by slip casting or CAD / CAM followed by glass infiltration Fracture strength = 6DDMPa

InCeram YZ (VITA)

Copings of anterior and posterior crowns; infrastructure of anterior and posterior fixed bridges

Densely sintered CAD / CAM processing Fracture strength >9DDMPa

Precera Alumina (Nobel Biocare)

Copings of anterior and posterior crowns; infrastructure of anterior and posterior fixed bridges of up to four elements

Densely sintered CAD / CAM processing Fracture strength >7DDMPa

Procera Zirconia (Nobel Biocare)

Copings of anterior and posterior crowns; infrastructure of anterior and posterior fixed bridges

Densely sintered CAD / CAM processing Fracture strength = 1,2DDMPa

ZirCAD (Ivoclar Vivadente)

Copings of anterior and posterior crowns; infrastructure of anterior and posterior fixed bridges

Densely sintered CAD / CAM processing Fracture strength >9DDMPa

LAVA (3M ESPE)

Copings of anterior and posterior crowns; infrastructure of anterior and posterior fixed bridges

Densely sintered CAD / CAM processing Fracture strength >1,1DDMPa

Cercon (Degudent)

Copings of anterior and posterior crowns; infrastructure of anterior and posterior fixed bridges

Densely sintered CAD / CAM processing Fracture strength >9DDMPa

Figure 10.

Figure 11.

Figure 10. Main contemporary etchable ceramic systems, indications and characteristics (FS - flexural strength, information provided by the manufacturers). Figure 11. Some of the main non-etchable contemporary ceramic systems, indications and characteristics (FS - flexural strength, information provided by the manufacturers).

309

and silanization, sandblasting with aluminum oxide and use of special primers (10-MDP monomer), sandblasting with aluminum oxide and use of special cements (10-MDP monomer) and, finally, an association between silica coating, silanization and application of primers or special cements (both with 10-MDP monomer). However, for the long-term, only the association of sandblasting with aluminum oxide and resin cements promotes the

When it comes to promoting increased longevity to anterior ceramic restorations, the clinician should be aware of the factors related to the patient, the quality of the remaining dental tissue and the ceramic system which is the most appropriate for each individual situation.59,16,19 THE PATIENT Several factors associated with the patient may influence the survival rate of veneers and anterior crowns. As with any restorative procedure, patients exhibiting a high risk of caries do not respond well to treatment because of the high incidence of secondary caries, especially if the margins of the preparations are located in dentin.52,68 Therefore, for these patients, any attempt to restore the anterior teeth should only be considered if monitoring and prevention measures have been established beforehand, if not the restorative healing treatment in these patients should be discouraged.87 The patient’s age makes a difference. The longevity of all-ceramic restorations may be impaired in individuals above 60 years of age.12 These patients may have occlusal overloading due to a lack of posterior tooth support and reduced salivary flow as a result of drug use and periodontal problems. Ceramic restorations may still exhibit poor performance in the elderly due to less or the absence of cervical enamel, it has gradually been worn with aging. Still, by the fact that root dentin exposure is common in such patients, the margins of the preparations are generally in dentin, which are more susceptible to microleakage.78,77,32,87 The above factors make elderly patients difficult to treat with anterior ceramic restorations. Extra attention and close monitoring of these patients should be performed, and patients should follow the clinical recommendations for better performance of the restorations. THE REMAINING DENTAL TISSUE The evaluation of the quantity and quality of the remaining dental tissue modulates the choice between crowns and ceramic veneers on anterior teeth. In developing the treatment planning, the clinician should determine whether the tooth is vital or endodontically treated. In the second case, the need for intracanal post cementation must be evaluated and the clinician must bear in mind that a minimum of 1,0 mm of dentin such as circumferentially localized must be maintained.83 The presence of a darkened substrate is common for endodontically treated teeth, therefore, generally a reduction of about 2.0 310

DECISION-MAKING: CERAMIC CROWNS OR VENEERS?

most stable bond strengths.75,9

mm is required to eliminate the chromatic influence of the preparation, giving the ceramist the possibility of creating room for a ceramic restoration with excellent aesthetic characteristics.15,64 Ceramic crowns are better restorative solutions than veneers for endodontically treated teeth19,15,64 because crowns provide increased strength, greater retention, better aesthetics and increased longevity, compared to ceramic veneers in this case. However, it should be considered that often the stability of a non-vital tooth is reduced due to the amount of structure removed during preparation.59,51 Ceramic veneers should be indicated only when bonding is totally viable. This signifies that the greater the amount of enamel, the better is the adhesion. The preparation for this restorative modality should primarily be confined to enamel, or display 70% of enamel, especially at the margins of the preparation.14,41 Complete cementation failures which cause debonding of the ceramic veneers have been reported in preparations exhibiting 80% of its area in dentin. These failures are unlikely to occur when a minimum of 0.5 mm of enamel is peripherally present.80,19,67 In this sense, to prevent microleakage events and secondary caries, it is essential that the margins of preparation are in enamel and free of composite,78,38 because partial adhesion to dentin or composite and the presence of high occlusal loads during static and dynamic occlusions increase the susceptibility of ceramic to fracture.78 Therefore, the ceramic crowns should be chosen in detriment to veneers if dentin is the primary substrate for bonding to a dental preparation, or in its margins, and also if there are extensive restorations such as class IV and III, the dimensions of which exceed the edge of the cervical enamel of the preparation. THE CERAMIC SYSTEM In a recent literature review carried out by Della Bona & Kelly,23 it was concluded that, for crowns and veneers, the clinician may choose any modern ceramic system. However, the choice of the ceramic system is highly dependent on the type of restoration (crowns or veneers), the type of cementation (adhesive or traditional), function and aesthetic demands of each case. Ceramics are particularly ideal for veneers and should, where possible, be indicated for additive reconstructions to restore lost enamel, ie without preparation. It is therefore crucial that the ceramic allows for hydrofluoric acid surface treatment, followed by silanization, in order to then be adhesively cemented.80,64 In addition, considering that aesthetics is of great interest for the anterior teeth, a ceramic system for these teeth would be relatively translucent, to allow the dental technician to build a chromatic expression inside the ceramic. Leucite-reinforced ceramics and traditional feldspathic ceramics are the materials that best meet these prerequisites.59,84,64 With respect to all-ceramic crowns, a wider range of systems may be used. Etchable leucite reinforced ceramics and lithium disilicate reinforced ceramics are suitable for cases where adhesive cementation is possible. Especially leucite-reinforced ceramics, which offer good tooth-ceramic bond trength to provide longevity and aesthetics.59,20,63 Ceramic systems which may not be adhesively cemented (not etchable), such as alumina and zirconia polycrystalline ceramics, are known as high-strength ceramics due to their 311

optimal mechanical properties and are important for patients with high functional and parafunctional occlusal loads. On the other hand, non etchable ceramics have low aesthetic characteristics and are recommended as infrastructure materials.59,51 These systems, in addition to the monolithic lithium disilicate crowns may be cemented with conventional glass ionomer or zinc phosphate cements.77,67,66 A general summary of the implications of crowns and ceramic veneers in anterior teeth is shown in Tables 1 and 2.

Table 1. Summary of the implications of crowns and ceramic veneers in anterior teeth ( - not recommended, + recommended).

ALL-CERAMIC CROWNS

EXTENDED CERAMIC VENEERS

Removal of tooth structure

−

+

Restoration stability

+

−

Tooth stability

−

+

+

− / +*

Risk of chromatic discrepancy due to tooth substrate * If less translucent glass-ceramics were employed.

Table 2. Recommendations for the selection of all-ceramic crowns and extended veneers in anterior teeth.

ALL-CERAMIC CROWNS Preparation margin localized in dentin

+ .

Non-vital teeth

+

Presence of extensive restorations

+ .

Presence of broad area of enamel also on the preparation margin

− . .

Discolored teeth

+

EXTENDED CERAMIC VENEERS. . + . . − / +*

Ceramics have played an important role in restorative dentistry and are the best materials to reproduce the aesthetic features of natural teeth. Advances related to their mechanical properties have been crucial to the universalization of their use. However, due to the great variability of available systems achieving clinical success, the professional must have a high level of awareness of the scientific evidence in order to properly choose the ceramic system, as much for optimizing the aesthetic result as well as for structural longevity of the restorative procedure.

312

CONCLUSIONS

* Use glass-ceramics with high capacity of substrate masking.

REFERENCES

1. Abduo J, Lyons K, Swain M. Fit of zirconia fixed partial denture: a systematic review. J Oral Rehab. 2010;47:866-76. 2. Alghazali N, Laukner J, Burnside G, et al. An investigation into the effect of try-in pastes, uncured and cured resin cements on the overall color of ceramic veneer restorations: an in vitro study. J Dent. 2010;38(Suppl 2):e78-86. 3. Andersson M, Oden A. A new all-ceramic crown: a dense-sintered, high purity alumina coping with porcelain. Acta Odontol Scand. 1993;51:59-64. 4. Atsu SS, Aka PS, Kucukesmen HC, et al. Age-related changes in tooth enamel as measured by electron microscopy: implications for porcelain laminate veneers. J Prosthet Dent. 2005;94(4):336-41. 5. Barghi N, Berry TG. Post-bonding crack formation in porcelain veneers. J Esthet Dent. 1997;9:51-4. 6. Belli R, Guimaraes JC, Filho AM, Vieira LC. Post-etching cleaning and resin/ceramic bonding: microtensile bond strength and EDX analysis. J Adhes Dent. 2010 Aug;12(4):295-303. 7. Belli R, Guimaraes JC, Lohbauer U, Baratieri LN. On the brittleness of dental ceramics: why do they fail? Quintessence Dent Tech. 2010;33:152-62. 8. Birmann MB. Cerâmica: arte da terra. São Paulo: Callis; 1987. 9. Blatz MB, Sadan A, Kern M. Resin-ceramic bonding: a review of the literature. J Prosthet Dent. 2003 Mar;89(3): 268-74. 10. Bottino MA, et al. Bonding of Y-TZP to dentin: effects of Y-TZP surface conditioning, resin cement type, and aging. Oper Dent. 2014 May;39(3):291-300. 11. Breschi L, Mazzoni A, Ruggeri A, Cadenaro M, Di Lenarda R, Dorigo EDS. Dental adhesion review: aging and stability of the bonded interface. Dent Mater. 2008;24(1):90-101. 12. Burke FJT, Lucarotti PSK. Ten-year outcome of porcelain laminate veneers placed within the general dental services in England and Wales. J Dent. 2009;37(1):31-8. 13. Chai J, Takahashi Y, Sulaiman F, Chong K, Lautenschlager EP. Probability of fracture of all-ceramic crowns. Int J Prosthodont. 2000;13:420-4. 14. Chang JC, Hart DA, Estey AW, Chan JT. Tensile bond strengths of five luting agents to two CAD-CAM restorative materials and enamel. J Prosthet Dent. 2003;90:18-23. 15. Cheung W. A review of the management of endodontically treated teeth: post, core and the final restoration. J Am Dent Assoc. 2005;136(5):611-9. 16. Christensen GJ. Are veneers conservative treatment? J Am Dent Assoc. 2006;137(12):1721-3. 17. Christensen GJ. Facing the challenges of ceramic veneers. J Am Dent Assoc. 2006;137(5):661-4. 18. Christensen GJ. Longevity versus esthetics: the great restorative debate. J Am Dent Assoc. 2007;138(7):1013-5. 19. Christensen GJ. Veneer mania. J Am Dent Assoc. 2006;137(8):1161-3. 20. Conrad HJ, Seong WJ, Pesun IJ. Current ceramic materials and systems with clinical recommendations: a systematic review. J Prosthet Dent. 2007;98(5):389-404. 21. De Munck J, Van Meerbeek B, Yoshida Y, Inoue S, Vargas M, Suzuki. K, et al. Four-year water degradation of total-etching adhesives bonded to dentin. J Dent Res. 2003;82(2):136-40. 22. De Souza G, Hennig D, Aggarwal A, Tam LE. The use of MDP-based materials for bonding to zirconia. J Prosthet Dent. 2014 Oct;112(4):895-902. 23. Della Bona A, Kelly JR. The clinical success of all-ceramic restorations. J Am Dent Assoc. 2008;139 Suppl:8S-13S. 24. Della Bona A, Mecholsky JJ, Anusavice KJ. Fracture behavior of lithia dissilicate and leucite-based ceramics. Dent Mater. 2004; 20(10):956-62. 25. Della Bona A. Restaurações em cerâmica pura. Clínica - Int J Braz Dent. 2009;5(3):328-32. 26. Donovan TE. Factors essential for successful all-ceramic restorations. J Am Dent Assoc. 2008;139 Suppl:14S-8S. 27. Dumfarht H, Schaffer H. Porcelain laminate veneers: a restrospective evaluation after 1 to 10 years of service. Part II: Clinical results. Int J Prosthodont. 2000;13:9-18. 28. Edelhoff D, Brix O. All-ceramic restorations in different indications: a case series. J Am Dent Assoc. 2011;142(4 suppl):1S-6S. 29. Edelhoff D, Güth JF, Lungwirth F, Fischer H, et al. Light transmission through lithium-disilicate ceramics with different levels of translucency. 45th Meeting IADR Barcelona 2010, J Dent Res. 2010;89: Special Issue B Abstract # 3660. 30. Elderton RJ. Clinical studies concerning re-restoration of teeth. Adv Dent Res. 1990;4:4-9. 31. Etman MK, Woolford MJ. Three-year clinical evaluation of two ceramic crown systems: a preliminary study. J Prosthet Dent. 2010; 103(2):80-90. 32. Featherstone JD. The science and practice of caries prevention. J Am Dent Assoc. 2000;131(7):887-99. 33. Filho AM, Vieira LC, Araújo E, Monteiro Junior S. Effect of different ceramic surface treatments on resin microtensile bond strength. J Prosthodont. 2004;13(1):28-35. 34. Fradeani M, Redemagni M, Conrado M. Porcelain laminate veneers: 6-to 12-year clinical evaluation: a retrospective study. Int J Periodontics Restorative Dent. 2005;25:9-17. 35. Fradeani M, Redemagni M. An 11-year clinical evaluation of leucite-reinforced glass-ceramic crowns: a retrospective study. Quintessence Int. 2002;33(7):503-10. 36. Frankenberger R, Reinelt C, Petschelt A, Krämer N. Operator vs. material influence on clinical outcome of bonded ceramic inlays. Dent Mater. 2009;25(8):960-8. 37. Frankenberger R, Taschner M, Gárcia-Godoy F, Petschelt A, Krämer N. Leucite-reinforcerd glass ceramic inlays and onlays after 12 years. J Adhes Dent. 2008;10(5):393-8. 38. Friedman MJ. A 15-year review of porcelain veneer failure: a clinician’s observations. Compend Contin Educ Dent. 1998;19:625-30. 39. Galiatsatos AA, Bergou D. Six-year clinical evaluation of ceramic inlays and onlays. Quintessence Int. 2008;39(5):407-12. 40. Garvie RC, Hannink RH, Pascoe RT. Ceramic steel? Nature. 1975;258:703-4. 41. Garvie RC, Nicholson PS. Phase analysis in zirconia systems. J Am Ceram Soc. 1972;55:303-5. 42. Guess PC, Stappert CFJ, Strub JR. [Preliminary clinical results of a prospective study of IPS e.max Press- and Cerec ProCad-partial coverage crowns]. Schwelz Monatsschr Zahnmed. 2006;116(5):493-500. 43. Guess PC, Stappert CFJ. Midterm results of a 5-year prospective clinical investigation of extended ceramic veneers. Dent Mater. 2008;24(6):804-13. 44. Haselton DR, Diaz-Arnold AM, Hillis SL. Clinical assessment of high-strength all-ceramic crowns. J Prosthet Dent. 2000;83:396-401.

313

45. Hilgert LA, Monteiro Jr. S, Vieira LCC, Gernet W, Edelhoff D. A escolha do agente cimentante para restaurações cerâmicas. Clínica - Int J Braz Dent. 2009;5(2):194-205. 46. Horn HR. Porcelain laminate veneers bonded to etched enamel. Dent Clin North Am. 1983;27(4):671-84. 47. Johnson GH, Craig RG. Accuracy of addition silicones as a function of technique. J Prosthet Dent. 1986; 55:197-203. 48. Jr C. Etched porcelain facial veneers: a new treatment modality based on scientific and clinical evidence. N Y J Dent. 1983;53(6):255-9. 49. Kelly JR. Dental ceramics: current thinking and trends. Dent Clin North Am. 2004;48(2):viii,513-30. 50. Kelly JR. Dental ceramics: what is this stuff anyway? J Am Dent Assoc. 2008;139 Suppl:4S-7S. 51. Kelly J, Benetti P. Ceramic materials in dentistry: historical evolution and current practice. Aust Dent J. 2011;56:84-96. 52. Kidd EAM, Fejerskov O. What constitutes dental caries? Histopathology of carious enamel and dentin related to the action of cariogenic biofilms. J Dent Res. 2004;83(Spec Iss C):35-8. 53. Krämer N, Ebert J, Petschelt A, Frankenberger R. Ceramic inlays bonded with two adhesives after 4 years. Dent Mater. 2006;22(1): 13-21. 54. Krämer N, Frankenberger R. Clinical performance of bonded leucite-reinforced glass ceramic inlays and onlays after eight years. Dent Mater. 2005;21(3):262-71. 55. Krämer N, Taschner M, Lohbauer U, Petschelt A, Frankenberger R. Totally bonded ceramic inlays and onlays after eight years. J Adhes Dent. 2008;10(4):307-14. 56. Kunii J, Hotta Y, Tamaki Y, Ozawa A, Kobayashi Y, Fujishima A, et al. Effect of shrinkage on the marginal and internal fit of CAD/ CAM-fabricated zirconia frameworks. Dent Mater. 2007;26(6):820-6. 57. Land CH. Porcelain dental art. Dent Cosmos. 1903;65:615-20. 58. Lange RT, Pfeiffer P. Clinical evaluation of ceramic inlays compared to composite restorations. Oper Dent. 2009;34(3):263-72. 59. Magne P, Douglas WH. Cumulative effects of successive restorative effects on anterior crown flexure: intact versus veneered incisors. Quintessence Int. 2000;31:5-18. 60. Magne P, Magne M, Belser U. The esthetic width in fixed prosthodontics. J Prosthodont.1999;8(2):106-18. 61. Magne P, Versluis A, Douglas WH. Effect of luting composite shrinkage and thermal loads on the stress distribution in porcelain laminate veneers. J Prosthet Dent. 1999;81:335-44. 62. Malament KA, Socransky SS. Survival of Dicor glass-ceramic dental restorations over 14 years. Part II: Effect of thickness of Dicor material and design of tooth preparation. J Prosthet Dent. 1999;81:662-7. 63. Mansour, YF, Al-Omiri MK, Khader YS, Al-Wahadni A. Clinical performance of IPS-Empress 2 ceramic crowns inserted by general dental practitioners. J Contemp Dent Pract. 2008;9(4):9-16. 64. Meijering AC, Creugers NHJ, Roeters FJM, Mulder J. Survival of three types of veneer restorations in a clinical trial: a 2.5-year interim evaluation. J Dent. 1998;26:563-8. 65. Naeselius K, Arnelund CF, Molin MK. Clinical evaluation of all-ceramic onlays: a 4-years restropective study. Int J Prosthodont. 2008; 21(1):40-4. 66. Ozkurt Z, Kazazoglu E. Clinical success of zirconia in dental applications. J Prosthodont. 2010;19(1):64-8. 67. Peumans M, De Munck J, Fieuws S, et al. A prospective ten-year clinical trial of porcelain veneers. J Adhes Dent. 2004;6:65-76. 68. Peumans M, Kanumili P, De Munck J, Van Landuyt K, Lambrechts P, Van Meerbeek B. Clinical effectiveness of contemporary adhesives: a systematic review of current clinical trials. Dent Mater. 2005;21(9):864-81. 69. Raigrodski AJ. All-ceramic full-coverage restorations: concepts and guidelines for material selection. Pract Proced Aesthet Dent. 2005;17:249-56; quiz 258. 70. Raigrodski AJ. Contemporary all-ceramic fixed partial dentures: a review. Dent Clin North Am. 2004;48:531-44. 71. Reich SM, Wichmann M, Rinne H. Clinical performance of large, all-ceramic CAD/CAM-generated restorations after three years: a pilot study. J Am Dent Assoc. 2004;135(5):605-12. 72. Rekow ED, Harsono M, Janal M, Thompsin VP, Zhang G. Factoerial analysis of variables influencing stress in all-ceramic crowns. Dent Mater. 2006;22:125-32. 73. Rosenblum MA, Schulman A. A review of all-ceramic restorations. J Am Dent Assoc. 1997;128(3):297-307. 74. Rouse JS. Full veneer versus traditional veneer preparation: a discussion of interproximal extension. J Prosthet Dent. 1997;78(6): 545-9. 75. Sadowsky SJ. An overview of treatment considerations for aesthetic restorations: a review of the literature. J Prosthet Dent. 2006; 96(6):433-42. 76. Scotti R, Cardelli P, Baldissara P, Monaco C. Clinical fitting of CAD/CAM zirconia single crowns generated from digital intraoral impressions based on active wavefront sampling. J Dent. 2011 Oct 17. 77. Shahverdi S, Canay S, Sahin E, Bilge A. Effects of different surface treatment methods on the bond strength of composite resin to porcelain. J Oral Rehabil. 1998;25(9):699-705. 78. Spear FM, Kokich VG, Mathews DP. Interdisciplinary management of anterior dental aesthetics. J Am Dent Assoc. 2006;137(2): 160-9. 79. Stoll R, Cappel I, Jablonski-Momeni, Pieper K, Stachniss V. Survival of inlays and partial crowns made of made of IPS Empress after 10-year observation period and in relation to various treatment parameters. Oper Dent. 2007;32(6):556-63. 80. Suputtamongkol K, Anusavice KJ, Suchatlampong P, et al. Clinical performance and wear characteristics of veneered lithia-disilicate-based ceramic crowns. Dent Mater. 2008;24(5):667-73. 81. Suttor D, Bunke K, Hoescheller S, Hauptmann H, Hertlein G. LAVA: the system for all-ceramic ZrO2 crown and bridge frameworks. Int Comput Dent. 2001;4:195-206. 82. Tay FR, Pashley DH, Suh BI, Carvalho RM, Itthagarum A. Single-step adhesives are permeable membranes. J Dent. 2002;30(7-8): 371-82. 83. Tay FR, Pashley DH. Resin bonding to cervical sclerotic dentin: a review. J Dent. 2004;32(3):73-96. 84. Toksavul S, Toman M. A short-term clinical evaluation of IPS Empress 2 crowns. Int J Prosthodont. 2007;20:168-72. 85. Van Noort, R. Introdução aos materiais dentários. 2a ed. Porto Alegre: Artmed; 2004. 86. Weinstein M, Katz S, Weinstein AB. Fused porcelain-to-metal teeth. U.S. Patent no. 3,052,982, Sept. 1962. Washinton, D.C.: U.S. Patent Office. 87. Yoshiyama M, Tay FR, Doi J, Nishitani Y, Yamada T, Itou K, et al. Bonding of self-etching and total-etching adhesives to carious dentin. J Dent Res. 2002;81(8):556-60.

314

315

chapter 8

impression taking for ceramic veneers the essence of communication Renata Gondo Machado | Rafael de Almeida Decurcio | Lúcio Monteiro

sential to the ceramist. The rehabilitation planning and photographic protocol are key elements linking this communication between professionals, the design of the preparation, the anatomy of adjacent teeth and the architecture of the periodontal tissues need to be replicated in detail, to enable the ceramist conditions for the implementation of their work to be accurate without questions or improvisations. Therefore, accuracy during the impressioning procedure is all to essential. The impression consists of a printing step with a specific material, which results in obtaining a mold, from which a model is prepared with a faithful copy of the teeth and adjacent structures of interest. Often this decisive step is neglected, carried out in a rush, in the final moments of a heavy consultation. As well as planning, preparation and cemen-

INTRODUCTION

When fabricating ceramic restorations, the transference of clinical information is es-

tation, the impression should be performed during a specific appointment, so that the professional and the patient may reach a satisfactory outcome. The professional must have scientific knowledge for the proper selection of materials and the correct execution of the technique, in addition to skill and access to specific tools. The purpose of this chapter is to guide the professional about the material choice and the step by step on how to carry out an impression, easily and effectively for predic-

The first step towards a high-quality impression is the proper material selection.1 Various types of impression materials are available on the market. The most suitable for ceramic veneers are polyvinylsiloxane-based elastomers, better known as addition-reaction silicones (or PVS), because of their excellent physical properties (Table 1). The name of the material stems from the chemical reaction by addition of silane and hydrogen groups, through vinyl double bonds.25 Since this reaction does not prsent any residual polymerization, nor release volatile by-products causing shrinkage, the result is a material with exceptional dimensional stability, which overrides all other available products. Therefore, it allows for the production of several models obtained from a single impression, with the same degree of precision.10 Ceramic veneers, contact lenses or fragment-type restorations impose a requirement of exacting detail in the reproduction of the substrate to be restored, because they do not allow for the minimal dimensional variations under the risk of misadaptation and hence immediate failure to the aesthetic result as well as reduced longevity. Long-term changes occur mainly from accelerated marginal leakage, due to the inevitable degradation of thickened resin cement, and hence the promotion of undesirable marginal staining. Since they exhibit a low coefficient of permanent deformation and excellent elastic recovery, the dimensional change after impression removal is virtually nonexistent.10 Another advantage is versatility and workability. In their commercial form, addition-reaction silicone is present in the form of a paste with different viscosities (high, medium, low and ultra-low), due to the amount of filler in the composition, lending their usage to a 318

IMPRESSION MATERIAL

table results in the production of ceramic veneers.

variety of techniques. This fact thus enables for the use of low viscosity materials (fluid) to capture fine details, such as in the case of termination of the preparation, as well as high viscosity materials (putty) as in the case of an individual tray, to help the infiltration of the low viscosity material into the gingival sulcus. The lower the viscosity, the better the reproduction of peculiarities; however, the greater will be the polymerization shrinkage.9 All pastes of different consistencies, have a base paste and a catalyst paste promoting the polymerization of the material. High-viscosity pastes are available in the form of tubes, dispensed using spoons or in cartridges for automatic mixing electronic equipment. Regular, light and ultra-light consistency pastes are found in cartridges in a self-mixing system. In this system, the silicone is mixed with a tip with built-in spirals, positioned within a special mixing gun dispenser. Thus, the material may be applied directly to the teeth and adjacent structures to be copied. These self-mixing systems guarantee superior proportioning, longer working time, and a more homogeneous mix, with less incorporation of bubbles, saving clinical time and material. For the patient, the material is pleasant, without taste or unpleasant odor. One disadvantage is the hydrophobicity of the material because of its chemical structure. Due to this property, contact with moisture decreases the quality of the results. To circumvent this inconvenience, surfactants have been added to some materials for promoting hydrophilicity. Hence, there has been an improvement in its flow and compatibility with moisture, along with a reduction in the incorporation of bubbles during pouring.9 However, even turning the materials more hydrophilic, the presence of saliva and blood also promote flaws. Therefore, moisture control is recommended throughout the impressioning procedure with addition-reaction silicones. On the market, there are excellent commercial products, such as Virtual (Ivoclar Vivadent, Liechtenstein) and Elite HD (Zhermack, Italy) (Fig. 1 and 2).

Table 1. Main properties of elastomers.

PROPERTY

ADDITION SILICONE

CONDENSATION SILICONE

POLIETHER

Detail reproduction

excellent

good

excellent

Dimensional stability

excellent

regular

very good

Elastic recovery

excellent

good

good

Ease of removal

moderate

easy

hard

Tear strength

satisfactory

satisfactory

satisfactory

Setting time

up to 6 minutes

8 minutes

6 minutes

Working time

medium/long

medium/long

short/medium

Pouring time

até 7-14 dias

up to 1 hour

up to 7 days

Shrinkage

0.05%

0.6%

0.15%

Cost

very high

regular

very high

Hydrophobicity

hydrophobic

hydrophobic

hydrophilic

Source: Adapted from Shillingburg & cols.,25 Baratieri & cols.,2,3 Pegoraro & cols.23 and Mesquita & cols.18

319

Figure 1a.

Figure 1b.

Figure 2a.

Figure 2b.

Figure 1. Virtual® (Ivoclar Vivadent, Liechtenstein).

After the setting of the impression material, the implementation of the technique must be meticulous. Remember, for a quality impression, a quality material is not enough. Knowledge is what promotes technical expertise and the skill of a professional. IMPRESSION TIMING Without any shade of doubt, material and technique are critical. The quality of the preparation and of the periodontium are also essential for positive results. A good impression demands cervical termination is at the appropriate gingival level without invasion of the biologic width, sharp and polished, for thorough reproduction. The periodontal tissues must be healthy. Inflamed gingiva presents edema and exudates, with frequent bleeding, compromising the infiltration and polymerization reaction of the impression material. In such cases, it is indicated to delay the procedure, and wait for the reestablishment of the periodontium rather than carrying out tentatives in adverse conditions.23 Often, with the presence of bleeding, the professional makes use of haemostatic agents. This practice is not recommended since their presence may adversely compromise the reproduction of the cervical margin, due to the hydrophobic characteristic of the impression material, as well as induce staining of the substrate to be restored, compromising the aesthetic result. It is very important that the very moment of impression taking is performed without being in a rush and in an organized manner. 320

STEP-BY-STEP OF IMPRESSION TAKING

Figure 2. Elite HD® (Zhermack, Italy).

PROPHYLAXIS In the case of procedures requiring provisional restorations, they must be carefully removed to prevent any damage to the periodontium. It is recommended to clean the dental surfaces with periodontal curettes and brushes (Microtuf®, Hot Spot Design), and pumice, until all provisional cement remnants and plaque are removed, in such a manner as to guarantee the best reproduction of the cervical termination.

TRAY SELECTION The impression for the preparation of ceramics veneers, require that stock trays to be utilized.4 According to the study by Cox & cols.,7 the more rigid the tray and the impression material, the better the quality of the work model. Partial plastic trays that allow for the simultaneous impression of the superior and inferior arches and the occlusal registration, are suitable for the impression in specific cases of a unitary preparation. Partial models must be attached to a functional partial articulator. However, these trays are more flexible and therefore less resistant to deformation caused by the weight of the stone during pouring, occurring distortions.8 With regard to ceramic veneers, as in the case presented in this chapter (Fig. 3-9), a full-arch impression is recommended, because the greater the amount of contact between the models, the more reliable and safe is its mounting in the articulator for the simulation of the disocclusion guides and functional adjustments.9 It is imperative that the ceramist has at their disposal all of the morphological nuances of the teeth within the arch and can reproduce the appropriately desireable harmonious symmetry, even in the case of unitary restorations. Thus, total rigid plastic stock or stainless steel trays are recommended (eg, Morelli® or Maquira®) (Fig. 10). Due to the metallic malleability of aluminum trays, and their possible promotion of considerable distortions in the impression, they are not indicated. The tray must cover all the teeth in the anteroposterior and lateral direction, with enough room for the impression material. The tray may not touch the teeth nor the periodontium or injure the patient. There is no need for customizing the tray with wax, due to the consistency of the silicone, allowing for the displacement of material, may interfere with the result. A specific adhesive should be applied (eg, Universal Tray Adhesive®, Zhermack, Italy) on the surface of the tray so that the impression material may adhere and thus contract in the direction of the tray during polymerization, avoiding deformations. A thin layer of adhesive is applied, 7 to 15 minutes before the impression procedure. Proper tray selection prevents unexpected errors from occurring making the time of impression taking comfortable and accurate. Neglecting this stage will result in a lack or an excess of material, discomfort to the patient, lack of stability of the mold and/or rupture in important sites.

321

Figure 3a.

Figure 3b.

Figure 3c.

Figure 4a.

Figure 4b.

Figure 5a.

Figure 5b.

Figure 6a.

Figure 6b.

Figure 3. Initial aspect of the face. Patient with complaints of aesthetic dissatisfaction due to gingival smile, length and visible shape of the teeth. (a) Right side view (b). Frontal view (c). Left side view. Figure 4. Initial appearance of dental-lip relationships. (a) Note the discrete display of the incisal edges of the maxillary incisors with the lips slightly parted. (b) In the forced smile, one may see impairment of the gingival aesthetics relationship and short clinical crowns. Figure 5. Aspect of the smile 90 days after periodontal surgery for clinical crown lenghtening. (a) Note the the gingival dominance of the central incisors. (b) Notice the harmony of the lip-gingival relationship. Figure 6. Preparation of the restorative trial (mock-up) by the indirect technique with bis-acrylic resin. (a) Insertion of composite resin along the incisal edge readjusting the incisal dominance. The procedure is performed without an adhesive surface treatment. (b) Finishing and polishing of the trial.

322

Figure 7a.

Figure 7b.

Figure 8a.

Figure 8b.

Figure 9a.

Figure 9b.

Figure 10.

Figure 7. Appearance of the smile after the restorative trial. (a) Note the proper exposure of the incisal edges. (b) Smile after the restorative trial. Note the harmony between length and width of the teeth, gingival contour and lips. Figure 8. Removal of composite restorations. (a) Superficial removal of the composite resin restoration in tooth #12. (b) The removal of the restoration with a #12 scalpel blade is recommended to prevent wear of enamel. Figure 9. (a) Smoothing of the angles and finishing of the preparation. (b) Appearance of the teeth after removal of the restorations and elimination of the undercuts. Figure 10. Selecting the tray.

323

GINGIVAL DISPLACEMENT Cervical termination of the preparation and the emergence profile are critical areas to be replicated in the working model for the manufacturing of ceramic veneers and contact lenses. In the case of gingival or intrassulcular termination, gingival displacement needs to be induced in order to allow for the access of the impression material into the sulcus. There are several methods of gingival displacement: • mechanical - displacement with impression copings or cords; • chemo-mechanical - displacement with chemically-soaked cords; • surgical; and • ultrasonic. The strategy we suggest is mechanical displacement by compression, with two non-impregnated cords. In this technique, the gingival margin has a vertical clearance for exposition of the tissue below the cervical preparation termination and a horizontal clearance towards the promotion of the proper thickness of the impression material. Many professionals consider this stage as being complex because they are not able to pack the cord and maintain it in the sulcus. This difficulty, most often occurs due to inadequate cord choice, inadequate packing in the sulcus and the use of inappropriate instruments. To select the ideal diameter of the cord, probing for determining the sulcus depth and the gingival biotype should be performed. The larger the sulcus depth and the thickness of attached gingiva, the greater the diameter of the indicated cord. If the thickness of the attached gingiva is less than 1 mm, the inadequate displacement may promote gingival recession.22,23 To control the moisture of the operative field and effective packing of the cords, it is recommended to carry out relative isolation, with the use of a lip retractor, cotton rolls and constant aspiration. Initially, one cord of a smaller diameter and an adequate length should be packed into the gingival sulcus, to encircle the entire buccal contour of the teeth to be restored. Packing of the cord should be carried out carefully with the proper spatula (packing instrument) (Fig.11), with light pressure for disruption of the junctional epithelium and irreversible damage to the gingival tissue not to occur. This first cord is intended to control gingival fluid moisture, to promote the vertical displacement and to limit the infiltration depth of the impression material to avoid excessively thin material and consequent tearing. This cord should be maintained inside the sulcus throughout the impression procedure (Fig. 12 and 13a). Then, a continuous cord of greater diameter is packed from the distal aspect of the most posterior tooth to be restored, on one side, to the distal aspect of the most posterior tooth on the opposite side, contouring the papillae.This cord must be placed partially deep, so that it is half exposed and half inside the sulcus so that it produces lateral displacement of the gingival margin. Leave one end of the cord out of the sulcus to facilitate its removal (Fig. 13b and 14). After positioning the cords, one should wait at least 5 minutes for the displacement of the gingival tissue to occur. Saliva control is required during the entire procedure for the gingival manipulation to be effective. 324

Figure 11.

Figure 12a.

Figure 12b.

Figure 12c.

Figure 13a.

Figure 13b.

Figure 14a.

Figure 14b.

Figure 11. Cord-packing Instrument. Figure 12. Gingival displacement. (a) Packing the first cord of a smaller diameter. (b) Notice the position of the cord packing instrument. (c) First cord positioned. Figure 13.Gingival displacement. (a) Aspect of packing the first cord from molar to molar (b) Packing the second cord Figure 14. Second cord packed (a) Buccal view. Note that the cord should be partially packed into the sulcus. (b) Incisal view.

325

IMPRESSION TAKING The principle of impression taking using the addition-reaction silicones consists of performing an imprint with a high-viscosity paste that promotes displacement of the tissue, and a low viscosity paste, which promotes the reproduction of the fine details. For this to occur, the impression may be performed in several ways. The technique influences the accuracy as well as the dimensional stability of the impression.16 The most common techniques of using materials of different viscosities are: • two-step impression; and • one-step impression. Two-step impression This technique is also known as: • double impression; • two-time impression; • wash-out technique; or • relief technique. The basis of the technique is to carry out a preliminary high-viscosity silicone impression, in the fabrication of a custom tray, followed by washing-out with a low viscosity silicone. This is the preferred procedure for the impression of preparations of multiple veneers and for contact lenses. The advantage is that the professional may perform the entire procedure with greater working time along with patient comfort. What is more, there is greater control over the application and distribution of the material. The first step should be the organization of the clinical desk with the following materials: • tweezers, periodontal probe and dental mirror; • lip retractor; • previously selected trays; • addition-reaction silicone - high and low viscosity pastes; • dosing spoons; • polyvinyl film (PVC); • dispensing gun for the low viscosity paste; • mixing and dispensing tips; and • adhesive for vinyl polysiloxane. The high viscosity material should be dispensed and manipulated for the first impression. In this system, the base and catalyst pastes are dispensed by volume, with an equal number of dosing spoons. As long as the proportions are respected, any formation of byproducts from the reaction will be avoided, ie, without dimensional changes and without compromise during pouring. Altered proportions negatively influence the final properties. Mixing of the masses must be performed manually without gloves and with well cleansed hands. Due to the fact that the sulfur from the latex gloves and talcum powder reacts with the chloroplatinic acid activator and inhibits the polymerization reaction. The cli326

nician should also avoid touching the preparations and the gingival tissue with latex gloves because it may also compromise the setting reaction. Often this change is not perceptible in the impression, only after pouring, into the model. To overcome this situation, in cases of tooth substrate contamination by the glove, cleansing with pumice is recommended.9 Using a rubber dam for absolute isolation may also contaminate the tooth substrate with sulfur and damage the impression. If the wish is to use gloves, the professional should opt for vinyl. Manipulation should be carried out “squeezing” the base and catalyst pastes between the fingers and hands, dynamically and quickly, to obtain a homogeneous mass without streaks. Check the working time for the material to be manipulated and inserted into the tray before offering compression resistance, otherwise it may cause strain during placement in the mouth, leading to distortions in the final impression. The high viscosity silicone may also be commercially presented in cartridges for self-mixing in an electronic device. In this system, the base and catalyst pastes are dispensed and automatically mixed, allowing for a faster protocol and more uniform material with lower incorporation of bubbles and risk of contamination.19 In addition it increases the working time,9 but requires a costly investment. After applying the adhesive for the silicone, the tray should be partially filled with the material. Excess putty material complicates the placement and the flow of the material. After filling, the positioning of a thin sheet of polyvinyl (PVC) over the surface of the high-viscosity silicone is recommended, in order to serve as a spacer between the putty material and the tooth, creating space for the wash-out of the low-viscosity material (Fig. 15a). In this manner, the need for subsequent relief of the impression is eliminated. The tray must be maintained in position for at least 4 minutes in accordance with the setting time recommended by the manufacturer. After removing the impression, the polyvinyl film should be removed, the try-in of the filled tray is recommended to try the insertion axis and to verify the adaptation. In cases of seating difficulties, the remaining excess and retentions should be properly removed to ensure the uniform thickness of the low-viscosity vinyl polysiloxane paste. If the polyvinyl film is not used, the relief of the impression should be performed with sharp instruments, trimming undercuts (interdental space, occlusal surface, gingiva and retentive edges), to ensure adequate and uniform thickness of the low-viscosity paste without pressure to the structures. Ideally, this relief will allow for for a material thickness of at most 2 mm.6 Greater reliefs are inadequate because there will be greater volume shrinkage of the low viscosity material, which results in dimensional changes.20 The relief technique through trimming is more complex due to the difficulty of controlling the amount of material removed. Furthermore, an inadequate relief may create an occlusal step on the adjacent teeth.5 As a result, relative isolation of the operative field and procedures for gingival displacement should be performed, as previously described. For impression with low viscosity silicone, an approximate 10 minute wait with the cords in position for subsequent removal of the second cord of a greater diameter is necessary. Excess moisture should be removed with compressed air. Avoid wetting the 327

entire operative field. Remember that moisture may compromise the impression in cases with hydrophobic material. Simultaneously with the removal of the second cord, the low-viscosity silicone should be inserted into the gingival sulcus over the first cord, throughout the extension of the cervical margin. For this, the cartridge with the base and catalyst pastes should be adapted to utilize a dispensing gun and the mixing and application tip properly positioned (Fig. 15b). After application of the pastes in the sulcus, a gentle air jet should be applied to ensure infiltration of the material (Fig. 16a). Care should be taken since excess air may promote the incorporation of bubbles. The low viscosity paste should cover the entire tooth, not only the cervical margins. The tray with high-viscosity paste should also be filled with low viscosity silicone, which ensures greater uniformity in the distribution of the paste. Professionals should exercise caution and control over the operative field, removal of the low viscosity paste by movement of the lips and tongue may occur during the placement of the tray. The assembly of high and low viscosity pastes into the tray must be brought into position. Great care must be taken in repositioning the tray within the patient’s mouth. Inadequate pressure may dislodge the low viscosity material, and promote an unsatisfactory impression.5 To remove the impression, one should wait a minimum of 5 minutes (Fig. 16b). Not complying with the setting time of the material can produce an impression with a rough and uneven surface.

Figure 15a.

Figure 15b.

Figure 16a.

Figure 16b.

Figure 15. Impression taking (a) Imprint with high viscosity silicone. Note that a polyvinyl film was used for the relief and as a spacer for the low-viscosity material. (b) Application of the low viscosity silicone on the surface of the teeth. Note that the material should be applied, first, along the cervical margin. Figure 16. Impression (a) After the application of the the low viscosity paste across all tooth surfaces, an air blast for improved infiltration and product distribution should be carried out. (b) Final impression. Notice that the first cord, which was kept in the sulcus during impression taking was removed with the mold, ensuring an appropriate copy of the cervical termination.

328

One-step impression In this technique, the impression is performed with high and low viscosity silicon, simultaneously. The procedure is simpler, faster and more comfortable for the patient. The advantage is the reduction of clinical time and material savings. However, the working time is shorter and there is the necessity of having a second person to carry out the manipulation of material.27 The professional should be concentrated and organized because there are several critical steps being performed at the same time.The application of the low viscosity material should be rapid, due to the fact that the previously manipulated high viscosity material is being polymerized. In the case of delay, the development of the elastic properties will start before the positioning within the mouth, as well as the resistance produced by the onset from polymerization of the high-viscosity paste may compromise the reproduction of tissues. Also with regard to positioning, bubbles which may occur due to excessive pressure as well as flow and rupture of the impression. Another disadvantage is the fact that the shrinkage of different viscosity materials takes place simultaneously ,which dimensionally alters the working model. Moreover, the reproduction of details may be accomplished by the high-viscosity paste, not exclusively by the low viscosity paste. The putty material tends to “push” the low viscosity paste off the preparation, so the critical areas, such as the cervical termination of the substrate to be restored may end up being covered by the putty mass which does not precisely copy the details.5 Therefore, we opted for the two-step impression technique for restorative procedures with ceramic veneers. There is a great controversy about the ideal impression technique. For some authors, there is no difference in the outcome,14,27 provided there is adequate gingival displacement.28 On the other hand, there are authors who advocate the implementation of the one-step impression,17,21 mainly for single preparations.11 Other authors further argue that the two-step technique promotes low dimensional variation compared to the one-step impression technique.5,10,20 Because the details are recorded only by the low viscosity material,5 which compensates for the deformation which may occur in the high-viscosity paste after removal from the mouth.6 Furthermore, since the wash-out is carried out after the complete polymerization of the putty paste, any and all shrinkage is restricted to the low viscosity paste, resulting in minimal dimensional change.5 The best choice must be made by the professional according to their working time and what best adapts to each technique, although the authors do recommend the use of the two-step technique. REMOVAL OF THE IMPRESSION The removal of the tray is a critical procedure which may compromise the accuracy of the impression.27 Initially, it is recommended to break the seal at the bottom of the vestibule with air blasts, which facilitates this procedure. The tray should never be removed through the use of undulating or tilting movements, but in a single motion and as parallel as possible to the long axis of the teeth. If the cord is removed together with the impression, this must be maintained, and the pouring performed over the properly positioned cord. If it is dislocated within the impression, do not try to carry out its repositioning. In this case, what would be the ideal would be to remove the cord. 329

ANALYSIS OF THE IMPRESSION A suitable impression is self-explanatory. When there is doubt, it means that the procedure should be reperformed. It is preferable to repeat the execution of the impression rather than sending it to the technician only to discover that the impression is unsuitable. A suitable impression should present: • a smooth and shiny appearance; • sharp edges; • the presence of a small amount of skirt material which has penetrated the gingival sulcus; • absence of bubbles and irregularities in areas that could compromise the fabrication of the restoration; • absence of visible areas of marked compression; and • absence of interdental ruptures. DISINFECTION OF THE IMPRESSION The stone models obtained from contaminated impressions are capable of transmitting microorganisms to those who manipulate them.26 Therefore, before being sent to the laboratory and / or poured, the impression must be properly rinsed and disinfected in solution: • 0.5% to 1% sodium hypochlorite; or • 2% glutaraldehyde. According to some authors,13 glutaraldehyde is the most effective bactericidal substance. The impression must be sprayed with disinfectant spray and placed in a plastic container, hermetically sealed, for 10 minutes and then be rinsed with tap water. immersion of the impression in a disinfectant substance may also be carried out, however soaking in a hypochlorite solution may have a corrosive effect on metal trays. STORAGE OF THE IMPRESSION Because of its dimensional stability, the impression may be stored for up to 14 days, provided that it is in a suitable environment and not manipulated. Storage at temperatures above 25 ° C may promote a dimensional change.15 POURING Due to the dimensional stability of the material and the absence of continuous polymerization,12 one can wait for 7 to 14 days for the pouring of the impression.1 The material may then be sent to the laboratory without the obligation of pouring, this function is delegated to the ceramist who is responsible for the production of restorations. The impressions should be sent along with the shade-matching information (Chapter 3), which includes the digital planning and photos with the shade guide after preparation or the removal of resins. These photographs should be taken prior to the impression, so that the dehydration of the teeth does not negatively interferes with the selection of the ceramic by the technician (Fig. 17). One should wait at least 1 hour before the pouring of the impression, because some trademarks exhibit a secondary reaction, which may lead to the formation of hydrogen gas as a byproduct from the polymerization. This release does not promote dimensional change but may induce the formation of porosity in the stone model.12 The wait time for pouring is also of great interest for the elastic recovery after removal from the mouth. Interestingly, the ceramist fabricates at least two working models (Fig. 20): one model for making dies; and another for the try-in of the restoration and reproduction of contact points and the emergence profile.

330

Figure 17a.

Figure 17b.

Figure 18a.

Figure 18b.

Figure 19a.

Figure 19b.

Figure 20a.

Figure 20b.

Figure 17. Shade selection Use of the shade guide and photography for communication with the ceramist. Figure 18. Fabricating the provisional restoration. (a) Spot-etching on the teeth to be provisionally restored. (b) Application of the adhesive system. Figure 19. Manufacturing of the provisional restoration. (a) Light curing of the adhesive system (b) Labial aspect of provisional restorations manufactured with composite resin. Figure 20. Ceramic veneers fabricated. (a) Labial aspect. (b) Palatal aspect. The appropriate impression allows for the production of models identical to the oral conditions.

331

The production of a study model of an ideal quality requires knowledge, the proper selection of material and a method for implementing the technique. The procedure is critical and very important towards the completion of the treatment (Fig. 21-26). Never neglect this step!

Figure 21.

Figure 22a.

Figure 22b.

Figure 23a.

Figure 23b.

Figure 23c.

Figure 23d.

Figure 21. Aspect immediately after cementation. Figure 22. Final appearance of the smile. Figure 23. Final aspect. (a) Mouth slightly open presenting proper tooth exposure with lips at rest. (b) aspect of the smile. (c-d) Note the texturization of the ceramics, giving a natural look.

332

Figure 24a.

Figure 24b.

Figure 25a.

Figure 25b.

Figures 24-26. Final aspect.

333

Figure 26a.

334

Figure 26b.

335

Figure 26 c.

Figure 26 d.

336

REFERENCES

1. Al-Zarea BK, Sughaireen MG. Comparative analysis of dimensional precision of different silicone impression materials. J Contemp Dent Pract. 2011;12(3):208-15. 2. Baratieri LN, et al. Odontologia restauradora: fundamentos & técnicas. São Paulo: Santos; 2010. 3. Baratieri LN, Monteiro Júnior S, Andrada MAC de, Vieira LCC, Ritter AV, Cardoso AC. Odontologia restauradora: fundamentos e possibilidades. São Paulo: Santos; 2002. 4. Brosky ME. Laser digitalization of casts to determine the effect of tray selection and cast formation technique on accuracy. J Prosthet Dent. 2002;87:204-9. 5. Caputi S, Varvara G. Dimensional accuracy of resultant casts made by a monophase, one-step and two-step, and a novel two-step putty/light-body impression technique: an in vitro study. J Prosthet Dent. 2008;99(4):274-81. 6. Chaimattayompol N, Park D. A modified putty-wash vinyl polysiloxane impression technique for fixed prosthodontics. J Prosthet Dent. 2007;98(6):483-5. 7. Cox JR, Brandt RL, Hughes HJ. A clinical pilot study of the dimensional accuracy of double-arch and complete-arch impressions. J Prosthet Dent. 2002;87(5):510-5. 8. de Lima LM, Borges GA, Junior LH, Spohr AM. In vivo study of the accuracy of dual-arch impressions. J Int Oral Health. 2014;6(3):50-5. 9. Donovan TE, Chee WW. A review of contemporary impression materials and techniques. Dent Clin North Am. 2004;48(2):vi-vii, 445-70. 10. Dugal R, Railkar B, Musani S. Dimensional accuracy when making impressions is crucial to the quality of fixed prosthodontic treatment, and the impression technique is a critical factor affecting this accuracy. J Int Oral Health. 2013;5(5):85-94. 11. Faria AC, Rodrigues RC, Macedo AP, Mattos Mda G, Ribeiro RF. Accuracy of stone casts obtained by different impression materials. Braz Oral Res. 2008;22(4):293-8. 12. Garone Netto N, Burger RC. Inlay e onlay metálica e estética. São Paulo: Quintessence; 1998. cap. 5, p. 65-71. 13. Hiraguchi H, Kaketani M, Hirose H, Kikuchi H, Yoneyama T. Dimensional changes in stone casts resulting from long-term immersion of addition-type silicone rubber impressions in disinfectant solutions. Dent Mater J. 2013;32(3):361-6. 14. Hung SH, Purk JH, Tira DE, Eick JD. Accuracy of one-step versus two-step putty wash addition silicone impression technique. J Prosthet Dent. 1992;67(5):583-9. 15. Kambhampati S, Subhash V, Vijay C, Das A. Effect of temperature changes on the dimensional stability of elastomeric impression materials. J Int Oral Health. 2014;6(1):12-9. 16. Levartovsky S, Zalis M, Pilo R, Harel N, Ganor Y, Brosh T. The effect of one-step vs. two-step impression techniques on long-term accuracy and dimensional stability when the finish line is within the gingival sulcular area. J Prosthodont. 2014;23(2):124-33. 17. Luthardt RG, Walter MH, Quaas S, Koch R, Rudolph H. Comparison of the three-dimensional correctness of impression techniques: a randomized controlled trial. Quintessence Int. 2010;41(10):845-53. 18. Mesquita E, Cé G, Thaddeu Filho M. Prótese unitária. Florianópolis: Ponto; 2008. 19. Nam J, Raigrodski AJ, Townsend J, Lepe X, Mancl LA. Assessment of preference of mixing techniques and duration of mixing and tray loading for two viscosities of vinyl polysiloxane material. J Prosthet Dent. 2007;97(1):12-7. 20. Nissan J, Gross M, Shifman A, Assif D. Effect of wash bulk on the accuracy of polyvinyl siloxane putty-wash impressions. J Oral Rehabil. 2002;29(4):357-61. 21. Pande NA, Parkhedkar RD. An evaluation of dimensional accuracy of one-step and two-step impression technique using addition silicone impression material: an in vitro study. J Indian Prosthodont Soc. 2013;13(3):254-9. 22. Pegoraro LF, et al. Prótese fixa. São Paulo: Artes Médicas; 1998. 23. Pegoraro LF, et al. Bases para o planejamento em reabilitação oral. São Paulo: Artes Médicas; 2013. 24. Raigrodski AJ, Dogan S, Mancl LA, Heindl H. A clinical comparison of two vinyl polysiloxane impression materials using the one-step technique. J Prosthet Dent. 2009;102(3):179-86. 25. Shillimburg Junior HT, Hobo S, Whitsett LD. Fundamentos de prótese fixa. Chicago: Quintessence; 1986. 26. Soares CR, Ueti M. Influence of different methods of chemical disinfection on the physical properties of type IV and V gypsum dies. Pesqui Odontol Bras. 2001;15(4):334-40. 27. Vitti RP, da Silva MA, Consani RL, Sinhoreti MA. Dimensional accuracy of stone casts made from silicone-based impression materials and three impression techniques. Braz Dent J. 2013;24(5):498-502. 28. Wöstmann B, Rehmann P, Trost D, Balkenhol M. Effect of different retraction and impression techniques on the marginal fit of crowns. J Dent. 2008;36(7):508-12.

337

chapter 9

provisional restorations for ceramic veneers Rafael Decurcio | Paula de Carvalho Cardoso | Luciano Reis Gonçalves | Fernanda Sakemi | Terence Romano

torations in teeth prepared for ceramic veneers compromises pulp health, increases the risk of caries on the surfaces of the prepared teeth and promotes gingival invagination over the prosthetic preparations.11 A well adapted and polished provisional restoration allows for better control of plaque and helps to maintain the gingival tissue healthy and with shape, position and an emergence profile ideally suited for the installation of ceramic veneers.11 They are also essential in maintaining the original tooth position when the preparation involves interproximal areas. The provisional restorations are a reflection of the wax-up and mock-up, consequently are key to increasing confidence between the patient and the professional, facilitating each step related to the accomplishment of the ceramic veneers.5,12

INTRODUCTION

Apart from the obvious dissatisfaction of the patient, the absence of provisional res-

In such cases of flaring, tooth crowding and the presence of restorations with oversized labial volume, it is impossible to fabricate the mock-up. In this situation, the provisional plays an essential role towards the aaesthetic definition and communication with the ceramist, lending greater predictability to the final outcome.16 So, it is advisable that the patient evaluates the results days after the insertion of the provisional, so that, if necessary, changes may be carried out on the desired morphology, providing that they are within the limits of the aaesthetic standards of reference. Further, as follows, an alginate impression is taken (Hydrogum 5, Zhermack, Italy) and sent to the ceramist, to be a reference of the length, width

Traditionally, the thermoplastic acrylic resin had been used as the material of choice for the provisional; However, for ceramic veneers, the first choices are composite resin and bisacryl, because of their improved mechanical and chromatic properties, as well as for their ease of handling.7,15,27 To successfully meet the above requirements, materials for the fabrication of veneers must have a number of ideal mechanical and physical properties, such as a high flexural strength, wear resistance, fracture toughness and a high dimensional stability.13,16 Bis-acrylic resins were introduced into the market in order to supplement some features of acrylic resins, such as ease of handling and the advantageous lower heating produced throughout the polymerization process, eliminating aggressions to pulp1,25 and soft tissues. The availability of bis-acrylic resins in self-mixing cartridges has allowed for more precise proportioning, in addition to having facilitated their use; at the same time, these composites have enhanced working time for the professional. The organic resin composition, inorganic fillers and monomers provides them with the aaesthetic and properties of strength similar to those of composites.23 However, bis-acrylic resins may present pigmentation from food or mouthrinses. In this manner, changing the original shade of the provisional restoration may be the source of an aaesthetic problem and result in patient dissatisfaction.9,20 The installation of provi340

MATERIALS AVAILABLE

and thickness of the ceramic veneers.

sional restorations must be preceded by a very rigorous timing schedule with respect to the ceramist, so that the interval between the provisional and the installation of the ceramic veneers is as brief as possible. Occasionally, mouthwashes with 0.12% chlorhexidine (Periogard®, Colgate, USA) are used for chemical control of dental plaque, thus avoiding its accumulation in areas with attached temporaries where there is little or no access for toothbrushing and flossing.2,22,26 However, this mouthwash may affect the color stability of the provisional restorations and cause further discoloration;8,24 a topic similar to that shown above, in which the time for completion of the case must be carefully planned with the ceramist in charge. One way to minimize this staining is through carrying out the polishing of the provisional bis-acrylic resin restorations after its instalation. Our Operative Dentistry team suggests performing the polishing with less abrasive rubbers (Composite Technique Kit®, Shofu, Japan) and zero pressure on the provisional under the risk of loss to its structure, considering the characteristic resilience of the material, and subsequent achievement of luster with extra-fine diamond paste or pumice with felt wheels. Another possibility described in the literature is the use of a glaze or polish coating (Biscover®, Bisco, USA), which reduces formation of biofilm on provisional restorations, beyond the possibility of offering a brighter, polished surface with color stability.6,14,23 Various techniques are described in the literature, including the indirect (laboratory) and direct techniques.3,4,10,21 Despite favorable reports on the the use of high chromatic and physical performance acrylic resin (Alike®, GC, USA) for provisionalization of ceramic veneers17 (Figure 1), our Operative Dentistry Team has a part of its protocol the use of direct provisional techniques, varying the restorative approach, in accordance with the material and the techncal ability of the professional.

Figure 1.

Figure 1. Acrylic resin of high chromatic and physical performance (Alike®, GC, USA).

341

A fast way for fabricating a direct provisional is the hands-free sculpture technique, highly indicated for situations involving a few veneers. However, the technique is absolutely dependent upon the professional skills of the dentist and therefore knowledge of tooth morphology is essential for the restoration of tooth shapes, surface textures and the proper inclination of the anterior teeth (Figure 4, Chapter 12). The composite resin selected for this technique should be easy to manipulate (Beautifil II®, Shofu, Japan; Empress Direct®, Ivoclar Vivadent, Liechtenstein) the use of several types of composites to reproduce dentin, enamel and their effects (Figures 2 to 7).

DIRECT TEMPORARIES

HANDS-FREE SCULPTURE WITH COMPOSITE RESIN (TABLE 1)

Defining the type of composite resin will depend upon the thickness that the provisional is required to restore. In cases where the thickness exceeds 1.2 mm the use of dentin resin (0.3 mm average) and a subsequent insertion of resin enamel (0.8 mm average) is suggested, dependent upon the involved third. Remember that all of the resin must initially be layered in the cervical third and after which it is layered towards the middle and the incisal thirds. Common errors such as graying have been observed when the sole use of enamel resin in the fabrication of a provisional veneer thicker than 1.5 mm. After selecting the desired composite and shade matching with the adjacent tooth or to be copied (see Chapter 3), the substrate is spot-etched, rinsed and dried, followed by an application of the adhesive system for further polymerization. Thereafter, a proper amount of resin is inserted with a spatula (Sofia® spatula, Golgran, Brazil) (Figure 8a-d) over the cervical region and the composite resin is accommodated with a brush soaked in a special liquid (Modeling Resin®, Bisco, USA) throughout the entire labial surface (Figure 8e-f ).

Table 1. Comparison between the mock-up techniques.

.

HANDS-FREE SCULPTURE WITH COMPOSITE RESIN

CLEAR MATRIX - COMPOSITE RESIN

SILICONE MATRIX - BIS-ACRYL RESIN

INDICATION .

A few teeth involving exclusively veneers

One or a few teeth exclusively involving veneers

Several teeth involving veneers and crowns

ABILITY TO SCULPTURE

Fundamental

Unnecessary

Unnecessary

NECESSITY OF WAXING

No

Mandatory .

Mandatory .

POLISHING STEP

Mandatory and laborious

Minimal

Mandatory and oversimplified

REPAIR

Easy

Easy

Easy

CLINICAL TIME

Upon the skill of the professional

Fast

Fast

HYGIENE .

Easy .

Easy .

Using special toothbrushes and floss with specific orientations

COLOR STABILITY

Excellent

Excellent

Needs care

REMOVAL TECHNIQUE

Hard

Hard

Moderate

TRADEMARKS

Beautifil® II, Shofu / Empress Direct®, Ivoclar Vivadent / Z350 XT®, 3M ESPE

Transil®, Ivoclar Vivadent / Elite Transparent®, Zhermack

Systemp C&B®, Ivoclar Vivadent / Protemp 4®, 3M ESPE

.

342

.

Figure 2.

Figure 3.

Figure 4.

Figure 5.

Figure 6.

Figure 7.

Figure 8a.

Figure 8b.

Figure 8c.

Figure 8d.

Figure 8e.

Figure 8f.

Figure 2. Initial smile with composite veneers exhibiting deficiency of shape and color. Figure 3. Lateral right smile demonstrating the presence of poor veneers. Figure 4. Initial intraoral photograph showing the presence of very opaque, dull restorations and staining at the interface. Figure 5. Smile after removal of defective composites showing the presence of generalized diastema in the anterior superior region. Note the presence of enamel on all of the teeth involved. Figures 6 and 7. Intraoral photographs after removing the defective composite restorations. Figure 8. In virtue of the presence of the previous composite resin restorations, the patient demanded the fabrication of temporaries and therefore it was decided to carry out composite resin temporaries for the six anterior superior teeth by the direct hands-free technique. (a) Spatula suitable for composite resin (Spatula Sofia®, Golgran, Brazil). (b) Composite resin (Beautifil II®, Shofu, Japan). (c) Seating of the composite on the spatula. (d-f) Insertion of a single increment on the cervical. With a brush soaked in Modeling Resin® (Bisco, USA), the resin is spreaded throughout the labial surface.

343

Figure 9a.

Figure 9b.

Figure 9c.

Figure 9d.

Figure 10a.

Figure 10b.

Figure 9. (a) Aspect after completion of the provisional on the left side. (b-d) View of the smile after temporization. Figure 10a-b. Final smile after cementation of the full-ceramic veneers without preparation or “contact lenses”.

Upon accomplishing the provisional of tooth #11 according to the digital planning, the adjacent teeth may then be used as a reference for the length and tooth inclination for the manufacturing of the other temporaries. However, patient evaluation is always best carried out while the patient is seated, face to face, for the correction of small details of length, tilting, incisal position and the set of temporaries, using aluminum oxide impregnated discs (Figure 9a-d). At this point, it is essential to analyze the function including the anterior guidance and disocclusion guides. Since these temporaries are fabricated joined, 344

the contacts between the teeth may be separated with serrated strips, in order to maintain space and facilitate hygiene. Patients with diastemas (small and parallel proximal walls) and with conoid teeth without composite restorations prior to the impression for further fabrication of the ceramic veneers do not necessarily require temporaries. After all, in these situations it is always possible to fabricate the mock-up, which already provides information and confirmation of the digital planning to the ceramist, without the need for preparations with dentin exposure. Therefore, the execution of the provisional and their removal would be a step that would involve greater clinical time, especially at the moment of the try-in of the ceramic veneers, which is restricted to teeth that have suffered wear from dentin exposure. In small preparations, eg evident worn edges or sharp incisal angles, the fabrication of temporaries should be abolished to avoid compromising the substrate available for bonding, being that it is aaesthetically unnecessary in view of the mock-up, which was previously approved by the patient, to be installed. Removing these provisional veneers involves reducing the labial volume with a coarse grained diamond point without irrigation, slowly and without pressure, generating the least amount of heat possible and thereby protecting the dentinopulpar complex. For the approach of the tooth structure, using #12 scalpel blades with precise movements between the tooth and the provisional veneer, promotes displacement in fragments (Figure 6, Chapter 12). This removal technique is possible when the composite resin layer is applied in a single increment; therefore, a large amount of resin, which will lead to a greater degree of polymerization shrinkage of the the entire set and therefore the possibility of easy removal, by the presence of a small gap formed by the shrinkage, as well as by the limited adhesion due to the spot etching. CLEAR MATRIX - COMPOSITE RESIN (TABLE 1) This technique does not rely on the professional’s technical skills, because the preparation of the provisional is performed with a clear matrix which copies the wax-up diagnostic carried out by the technician during the previous phases of treatment planning or through the use of the copy of a natural tooth (eg darkened with adequate form) or even of the provisional already installed prior to the execution of the preparation. The technique involves the use of a clear low/medium viscosity addition silicone (Transil®, Ivoclar Vivadent, Liechtenstein; or Elite Transparent®, Zhermack, Italy). This silicone is dispensed on the stone model of the diagnostic wax or directly within the patient’s mouth, on the substrate to be copied, but requiring restorative intervention or which already possesses a provisional veneer to be replaced, provided that it has an acceptable morphological condition (Figures 11 to 13). This clear matrix is stored for use after the preparation (Figure 14) and subsequent intra-oral preparations of the temporaries in order to enable the use of the composites, due to the passage of light, less internal porosity of the composite, surface smoothness, the addition of small increments and light-curing of composites in the absence of oxygen. 345

Figure 11a.

Figure 11b.

Figure 13.

Figure 15a.

Figure 12.

Figure 14.

Figure 15b.

Figure 15d.

Figure 15c.

Figure 15e.

Figure 11. (a) Initial smile prior to the removal of the orthodontic appliance. (b) Initial intraoral photograph. Figure 12.Initial situation immediately after removal of the upper orthodontic appliance. Figure 13. After the improvement of shape and contour of the existing restorations (without conditioning and without proximal individualization), the clear silicone was positioned (Elite Transparent®, Zhermack, Italy) directly within the mouth given an acceptable morphological condition. Figure 14. Appearance after removal of composites. Figure 15. (a) First point of etching. (b) Adhesive application. (c-d) Insertion of the composite resin in the clear silicone matrix. (e) Final appearance after matrix removal.

346

There are two possibilities for use of the clear matrix: 1: Two steps - without carrying out a spot etching and prior adhesive application, so that the composite resin, after curing, will be captured by the clear matrix during its removal. In this manner, the margins may be extra-buccally adjusted as well as polished, and then the provisional is to be cemented with a flowable composite (Tetric Flow® T, Ivoclar Vivadent, Liechtenstein) after spot etching and the application of the adhesive on the teeth. Each tooth is polymerized for 30 seconds with a conventional light; and 2: Single step - after the teeth are prepared, they are spot-etched, and then an adhesive is applied and cured. To follow, the matrix is loaded with resin, of the chosen shade, and is gently placed on the prepared teeth. After curing, coarse finishing takes place and if necessary, the interdental contacts are separated with serrated strips. However, in most cases the contacts are maintained together, and the patient is instructed as to hygiene (Figure 15). Excesses should not be kept beneath the gingival tissue, and, in this case, extremely fine diamond points are indicated (#1190, KG®, Brazil), without damaging the dentogingival complex. In case of bubbles, repairs may be carried out with composite resin, and the final appearance will be extremely agreeable and the patient will experience temporary functional and aaesthetic comfort while waiting for the completion of the restorative process with ceramic veneers (Figures 16 and 17).

Figure 16.

Figure 17a.

Figure 17b.

Figure 17c.

Figure 16. Ceramic veneers positioned on the stone model. Figure 17a-c. Final smile.

347

SILICON MATRIX - BIS-ACRYL RESIN (TABLE 1) The introduction of bis-acryl resin greatly facilitated the provisionalization stage by the rapid transfer of the diagnostic wax-up to the patient’s mouth, serving as a trial step as well as for the temporaries after patient approval of the mock-up. This type of material exhibits a suitable surface smoothness promoting patient comfort and temporary aaesthetics, as well as a consistency that allows for easy removal of excesses. From the diagnostic wax-up with the optimal dimensions established by the aaesthetic rehabilitation planning (Chapter 4) and a maximum of morphological characteristics and surface texture established a silicone guide is then fabricated (Figures 18 to 20). The fabrication of the guide involves the use of silicone, preferably laboratory (Zeta-

Figure 18b.

Figure 18c.

Figure 18a.

Figure 19a.

Figure 19b.

Figure 19c.

Figure 19d.

Figure 19e.

Figure 19f.

Figure 19g.

Figure 18. (a) Initial aspect of the face. (b) Initial smile. (c) Intraoral photograph revealing the presence of chipped, deficient composites from 13 to 23. Figure 19. (a) Removal of the resin composites with disks (Sof-Lex Pop-On®, 3M ESPE, USA). (b) Careful use of the scalpel with a #12 blade. (c) Removal of the resin of tooth #11 indicating the presence of staining on the mesial of #12. (d) Lateral aspect after removal of #12 and #13 restorations. (e) Frontal view after complete removal of deficient composite restorations. (f) Phosphoric acid etching in the middle third. (g) Adhesive application.

348

labor®, Zhermack, Italy). First, the high viscosity paste is applied firmly on the wax model, involving all the buccal and lingual surfaces, together with thickness to facilitate its correct positioning within the mouth. Following polymerization, the high viscosity silicone guide is removed from the model and relined with low viscosity silicone (Oranwash®, Zhermack, Italy), without a relief, allowing for a superior copy of the morphological details and surface texture from the produced wax-up, and the installation of temporaries with less excess and a more refined anatomy. To facilitate removal of the excess bis-acrylic resin, the guide must be trimmed with a scalpel blade #12 approximately 2 mm from their gingival margin following the contour of the waxed teeth, so that there is a minimum amount of resin in the region to be easily

Figure 20a.

Figure 20c.

Figure 20b.

Figure 20d.

Figure 20e.

Figure 20. (a) Tooth wax-up used and approved by the mock-up. (b) Bis-acryl resin (Protemp 4®, 3M ESPE, USA). (c) Insertion of the bis-acryl resin in the silicone guide. (d) Positioning of the guide filled with bis-acryl resin within the mouth. Observe the removal of gross excesses with a explorer. (e) Result immediately after removal of the guide.

349

dislocated. Ideally, the palate copied by the silicone also must be trimmed out to allow for a maximum flow of resin excesses in the region, avoiding overcontours in the mock-up.18 Then, spot etching is carried out at a point central to the prepared teeth, followed by an adhesive application, then light curing takes place. After the discarding of the small initial portion, which normally does not polymerize, bis-acrylic resin in a self-mixing dispensing gun must be then dispensed on the guide so that the first portions are placed with mixing tip touching the bottom of the guide. This maneuver minimizes the formation of bubbles in the temporaries and promotes an even distribution of resin inside the guide. Loading the guide should be fast due to the rapid polymerization reaction of this material, which then should be brought to the patient’s mouth and pressed firmly into place. For this, pressure must be carried out in the occlusal-cervical direction in the guide over the teeth not involved in the rehabilitation, to allow for the full and proper seating of the assembly.18 The excesses extravasated from the buccal and palatal surfaces are light cured and removed with the use of explorer and tweezers, to minimize the adjustments to be made with a scalpel blade after the curing of the resin which will occur after 5 minutes with the silicone guide in a static position within the mouth. After 5 minutes from the polymerization of the bis-acrylic resin and removal of the extravasated excesses, the guide may then be carefully removed from the patient’s mouth. The permanence of the provisional for an extended period requires extra care such as: • slight opening of the cervical embrasures, to enable cleaning with specific devices (see Chapter 13); and • polishing without pressure using aluminum oxide impregnated discs, abrasive rubbers and felt disks impregnated with polishing paste. Small repairs may be performed if there is bubble formation or if resin portions break, along with the excesses. However, unlike the mock-up, which will remain in the mouth for a short period, repairs on the provisional with bis-acryl should be accomplished after the application of the bonding agent (Figure 21). The removal of the fabricated provisional with bis-acryl resin is easy and without risks of contacting the diamond point with the dental substrate.In this manner, the try-in session and cementation with this temporization technique is faster (Figure 22). In conclusion, it is essential that all restorative, biological and functional principles are respected in the installed temporaries, for the rehabilitation process with ceramic veneers is to be easily implemented. Definitively, the installation of the temporaries should be restricted to the prepared teeth, since, no matter how precise they are, the provisional stage is always difficult to control by the professional and the patient.

350

Figure 21a.

Figure 21b.

Figure 21c.

Figure 22a.

Figure 22b.

Figure 22c.

Figure 21. (a) Zero pressure polishing with abrasive rubber for composite resin (Composite Technique Kit®, Shofu, Japan). (b-c) Final aspect of the provisional. Figure 22. (a) Cemented ceramic veneers - frontal view. (b) Final intraoral lateral view. (c) Final smile. (d) Final aspect of the face.

351

Figure 22d.

352

REFERENCES

1. Altintas SH, Yondem I, Tak O, Usumez A. Temperature rise during polymerization of three different provisional materials. Clin Oral Investig. 2008 Sep;12(3):283-6. Epub 2007 Dec 15. 2. Bagis B, Baltacioglu E, Özcan M, Ustaomer S. Evaluation of chlorhexidine gluconate mouthrinse-induced staining using a digital colorimeter: an in vivo study. Quintessence Int. 2011;42:213-23. 3. Baratieri LN, Guimarães J. Laminados cerâmicos. In: Baratieri LN, Guimarães J, . Monteiro Jr S, Perdigão J, Bernardo JK, Zombonato R, et al. Soluções clínicas: fundamentos e técnicas. Florianópolis: Ponto; 2008. p. 214-71. 4. Bennani V. Fabrication of an indirect-direct provisional fixed partial denture. J Prosthet Dent. 2000;84:364-5. 5. Burns DR, Beck DA, Nelson SK, Committee on Research in Fixed Prosthodontics of the Academy of Fixed Prosthodontics. A review of selected dental literature on contemporary provisional fixed prosthodontic treatment: report of the Committee on Research in Fixed Prosthodontics of the Academy of Fixed Prosthodontics. J Prosthet Dent. 2003 Nov;90(5):474-97. 6. Davidi MP, Beyth N, Sterer N, Feuerstein O, Weiss E. Effect of liquid- polish coating on in vivo biofilm accumulation on provisional restorations: part I. Quintessence Int. 2007;38:591-6. 7. Diaz-Arnold AM, Dunne JT, Jones AH. Microhardness of provisional fixed prosthodontic materials. J Prosthet Dent. 1999;82:525-8. 8. Doray PG, Li D, Powers JM. Color stability of provisional restorative materials after accelerated aging. J Prosthodont. 2001;10:212-6. 9. Dory PG, Wang X, Powers JM, Burgess J. Accelerated aging affects color stability of provisional restorative materials. J Prosthod. 1997;6:183-8. 10. Fehling AW, Neitzke C. A direct provisional restoration for decreased occlusal wear and improved marginal integrity: a hybrid technique. J Prosthodont. 1994;3:256-60. 11. Fradeani M. Análise estética: uma abordagem sistemática para o tratamento protético. São Paulo: Quintessence; 2006. 12. Gordon JC. Provisional restorations for fixed prosthodontics. J Am Dent Assoc. 1996;127(2):249-52. 13. Hernandez EP, Oshida Y, Platt JA, et al. Mechanical properties of four methylmethacrylate-based resins for provisional fixed restorations. Biomed Mater Eng. 2004;14:107-22. 14. Higashi C, Gomes JC, Kina S, Andrade OS, Hirata R. Planejamento estético em dentes anteriores. Odontologia Estética. 2006; 7:139-54. 15. Ireland MF, Dixon DL, Breeding LC, et al. In vitro mechanical property comparison of four resins used for fabrication of provisional fixed restorations. J Prosthet Dent. 1998;80:158-62. 16. Kaiser DA. Accurate acrylic resin temporary restorations. J Prosthet Dent. 1978;39:158-61. 17. Magne P, Belser U. Bonded porcelain restorations in the anterior dentition: a biomimetic approach. Carol Stream: Quintessence; 2002. 18. Magne P, Belser UC. Novel porcelain laminate preparation approach driven by a diagnostic mock-up. J Esthet Restor Dent. 2004;16(1):7-16. 19. Nixon RL. Provisionalization for ceramic laminate veneer restorations: a clinical update. Pract Periodontics Aesthet Dent. 1997 Jan-Feb;9(1):17-27; quiz 28. 20. Sham AS, Chu FC, Chai J, Chow TW. Color stability of provisional prosthodontic materials. J Prosthet Dent. 2004;91:447-52. 21. Small BW. Indirect provisional restorations. Gen Dent. 1999;47:140-2. 22. Sorensen JA, Doherty FM, Newman MG, Flemmig TF. Gingival enhancement in fixed prosthodontics. Part I: Clinical findings. J Prosthet Dent. 1991;65:100-7. 23. Strassler H, Lowe RA. Chairside resin-based provisional restorative materials for fixed prosthodontics. Compendium of Education in Dentistry. 2011;32(9):10-9. 24. Turgut S, Bagis B, Ayaz EA, Ulusoy KU, Altintas SH, Korkmaz FM, Bagis N. Discoloration of provisional restorations after oral rinses. Int J Med Sci. 2013 Aug 30;10(11):1503-9. 25. Wang RL, Moore BK, Goodacre CJ, Swartz ML, Andres CJ. A comparison of resins for fabricating provisional fixed restorations. Int J Prosthodont. 1989 Mar-Apr;2(2):173-84. 26. Yannikakis SA, Zissis AJ, Polyzois GL, Caroni C. Color stability of provisional resin restorative materials. J Prosthet Dent. 1998;80:533-9. 27. Young HM, Smith CT, Morton D. Comparative in vitro evaluation of two provisional restorative materials. J Prosthet Dent. 2001;85:129-32.

353

SECTION IV. CEMENTATION

DENTAL ADHESION | RESIN CEMENTS | CEMENTATION

chapter 10

dental adhesion Ana Paula Rodrigues de Magalhães | Paula de Carvalho Cardoso

tanding of this mechanism was essential for the evolution of Dentistry as we know it today and key to the development of ceramic veneers. 60 years ago a procedure like this, where there is almost no preparation or macromechanical retention and which extremely thin porcelain veneers are applied, was virtually impossible to be accomplished. Developments in studies on adhesion process is directly responsible for the strength and longevity of this restorative type. The concept of adhesion is relatively novel in dentistry, have been introduced in 1955 by Michael Buonocore,1 which showed that when treated with 35% phosphoric acid, enamel exhibited a porous surface which could then be infiltrated by resin, improving the durability of the adhesion. From this work, numerous other studies have been developed to enhance the enamel etching, including discussions over the etching of dentin and ceramics, which has led to the development of adhesive systems. The purpose of the adhesive restoration is to achieve a well-fit, sealed adaptation between the restorative material and the tooth substrate.24 The fundamental mechanism of adhesion for both enamel and dentin is based on an exchange process wherein minerals are removed from the dental tissues and then are replaced by resinous monomers, which, after polymerization, have become mechanically interlocked through the porosities created.2 This micromechanical interlocking of monomers to the dental substrate may result in minimal postoperative sensitivity, improved marginal fit, preventing fluid infiltration inside the tubules as well as acting as an elastic cushion which compensates for the forces generated by the polymerization shrinkage of the resinous material.16,25 To reach this end it was necessary to understand the heterogeneity of both substrates which occurs this union, enamel and dentin, in addition to knowing the physicochemical properties and the mechanisms of action of available adhesive systems. The biggest challenge of dental adhesives is to promote an equally effective adhesion to these two hard tissues of different nature.33

ENAMEL Enamel is the outermost tissue of the tooth, composed of 96% hydroxyapatite, being therefore, in its majority mineral.25 The use of acids for the treatment of tooth surfaces is primarily based on increased contact surface area through the creation of microporosities, a purely physical phenomenon. In addition, acids are also able to increase the wettability or the free surface energy, allowing for a more intimate contact between resin and enamel, which also favors the adhesion1,18 (Figure 1). Enamel bonding remains the most well-established mechanism of dental adhesion. during which, acid etching selectively dissolves enamel prisms and creates microporosities, which are then penetrated by bonding agents, even hydrophobic agents, through capillarity (Figure 2). After polymerization, small prolongations of resinous monomers are 358

ADHESION

Adhesion is the mechanism that binds two interfaces in close contact. The unders-

formed between the prisms and create the best possible adhesion to the dental substrate. It does not only effectively seal the margins of the restoration but also protects the vulnerable dentin adhesion from degradation.2,7,25 With ceramic veneers treated with hydrofluoric acid (see details in chapter 12) (Figure 3), the preparation should ideally be restricted to enamel, owed to the foreseeable adhesion and superior bond strength found in this tissue (Figures 4 e 5).

Figure 1.

Figure 2.

Figure 3.

Figure 1. 37% phosphoric acid (Power Etching®, BM4, Brazil). Figure 2. Enamel etching with 35% phosphoric acid (Power Etching®, BM4, Brazil) for 30 seconds (x3,000). Figure 3.Feldspar ceramic etched with 5% hydrofluoric acid for 90 secondss (x25,000). SEM micrographs of Figures 2 and 3 undertaken and courtesy by Professor Sillas Duarte and Professor Neimar Sartori, UCLA, USA.

359

Figure 4.

Figure 5.

Figure 4. Adhesive interface of a porcelain veneer adhered to enamel (x3,000) (R: resin cement; HL: Hybrid layer of enamel; E: enamel). Figure 5. Close-up view of the adhesive interface of a porcelain veneer adhered to enamel. Note the presence of the hybrid layer of enamel (x6,000) (A: adhesive layer; HL: hybrid layer of enamel; E: enamel). SEM micrographs of Figures 4 and 5 kindly provided by Professor Sillas Duarte and Professor Neimar Sartori, UCLA, USA.

360

DENTIN While enamel adhesion is extremely effective and reliable, adhesion in dentin has long since been considered difficult and less predictable.This is due to its composition and morphology, which are very particular and greatly differ from those found in enamel. Dentin consists mainly of water, organic matter and type I collagen.25 Dentin possesses dentinal tubules, in which, due to differences in pressure from external and internal environments the dentinal fluid circulates, leaving dentin naturally moist and therefore intrinsically hydrophilic.2 Moreover, dentin is considered a dynamic tissue, which changes through aging, in reaction to caries and restorations.30 In addition to being a very heterogeneous tissue when subjected to tooth preparation, dentin is covered by a layer of debris, which blocks the entrances of the dentinal tubules, reducing their permeability. This layer is called the smear layer or dentin mud.2,25 This smear layer should be dissolved so that the adhesive monomers are able to enter into contact with the dentin surface;25 furthermore modifications should be made on the dentin surface for the mechanical interlocking of the adhesive to occur in its structure.30 The use of phosphoric acid etching for dentin, then, has the function of removing the smear layer and promoting its demineralization, exposing the collagen fibrils (Figures 6 e 7). This layer composed by the organic components of dentin as well as hydroxyapatite permeated by adhesive monomers and water constitutes what is called the hybrid layer.20,25 In the case of ceramic veneers, adhesion entirely carried out in dentin is a challenge. Notice in Figure 8 the presence of an adhesive failure forming a gap at the interface and the absence of resinous prolongations within the dentinal tubule (see Chapter 6, on dentin preparation). Several studies have been developed to understand its structure, formation and how it can be improved, for without the formation of a well-established hybrid layer there is no bonding.30 In recent years, discussions have been raised as to the degradation of the hybrid layer over time caused by enzymes present on the very fibrils of the dentin collagen, the matrix metalloproteinases.4,6,27,29 This process mainly occurs due to the discrepancy between the depth of the demineralization of dentin and its infiltration by the adhesive monomers, resulting in voids within the deepest portions of the hybrid layer, which therefore present exposed collagen.24,27 The presence of acidic agents, such as those produced by bacteria, from the acid etching or from the acidic monomers of the very adhesive system itself catalyze the action of these metalloproteinases, which initiate the degradation of the exposed collagen, reducing the bond strength and durability of this interface.24 In an attempt to increase the longevity of restorations, metalloproteinase inhibitors have been suggested for their concurrent use with adhesives, such as chlorhexidine, which has shown promising results by presentinf a chelating action over such enzymes.4,6,27,29 However, the authors do not indicate this practice, because in addition to being another step open to

361

Figure 6.

Figure 7.

Figure 6. Human dentin etched with 37% phosphoric acid (Power Etching®, BM4, Brazil) for 15 seconds (x5000). Figure 7. Longitudinal view of conditioned human dentin with 37% phosphoric acid (Power Etching®, BM4, Brazil) for 15 seconds (x6000). SEM micrographs of Figures 6 and 7 undertaken and kindly provided by Professor Sillas Duarte and Professor Neimar Sartori, UCLA, USA.

362

Figure 8.

Figure 8. Adhesive interface of a porcelain veneer with margins in dentin. Note the presence of an adhesive failure forming a gap at the interface and the absence of resin plugs inside the dentinal tubules (R: resin cement; G: interfacial gap; HL: hybrid layer in dentin; D: dentin). SEM micrograph, courtesy of Professor Sillas Duarte and Professor Neimar Sartori, UCLA, USA.

error with respect to the adhesive luting, calcium ions released by the primer itself may account for the loss of its inhibitory activity, with very high concentrations of chlorhexidine required to achieve the expected goal.29 In addition, with the advent of self-etching and multimode adhesives, this divergence between the depth of etching and penetration of the adhesive becomes minimal, since these two processes occur simultaneously with the use of the acidic primer, it is preferable to adopt another bonding system than to add more steps to a procedure which is already complex. The organic, hydrophilic and dynamic nature of dentin represent a major challenge for adhesive interaction with this dental tissue, leading to a constant search for different bonding strategies.

363

The adhesive systems have experienced several classifications over the years: by the number of steps, by the type of etching,and by the generations of adhesives. For the authors, the most appropriate and current classification is the type of conditioning of dental tissues, ie by the manner inwhich these adhesive systems interact with enamel and dentin surfaces. The adhesive systems are thus divided into three groups: total etching;

THREE-STEP

MULTIMODE

etchant, primer and adhesive in separate bottles total demineralization of enamel and dentin gold standard in adhesion technique-dependent post-operatory sensitivity

• separate etchant, primer and adhesive in the same vial • total demineralization of enamel and dentin • technique-dependent post-operatory sensitivity

TWO-STEP

• • • •

acidic primer and adhesive in separate steps chemical bonding to tooth structure do not remove smear layer - lower hybrid layer minimized post-operatory sensitivity

ONE-STEP

• • • •

aka “all-in-one” chemical bonding to tooth structure hybrid layer thinner than two-step SEPs less post-operatory sensitivity

TWO-STEP

ONE-STEP

Figure 9.

Figure 9. Schematic drawing of the current classification of adhesives.

364

• • • •

TWO-STEP

SELF-ETCH

TOTAL-ETCH

self-etching; and most recently, the multimode adhesives.

ADHESIVE SYSTEMS

CLASSIFICATION (FIGURE 9)

• adhesive eith acidic monomers • possibility of choosing between techniques accordant to the clinical indication • chemical bonding to the tooth structure • decreased post-operatory sensitivity • selective etching of enamel is suggested for better marginal sealing

Table 1. Commercial brands of adhesive systems according to the classification (Figure 9).

CLASSIFICATION

COMMERCIAL BRANDS

Three-step total-etching systems

Scothbond Multi Purpose® (3M ESPE), All Bond 3® (Bisco)

Three-step total-etching systems . .

Exite F® (Ivoclar Vivadent), Exite F DSC® (Ivoclar Vivadent), Tetric N Bond® (Ivoclar Vivadent), Single Bond 2® (3M ESPE), Prime &Bond 2.1® (Dentsply), One Coat Bond SL® (Coltene), One Step® (Bisco), One Step Plus® (Bisco)

Two-step, self-etching systems .

Adper SE Plus® (3M ESPE), Clearfil SE Protect® (Kuraray), Clearfil SE Bond® (Kuraray), AdheSE DC® (Ivoclar Vivadent)

One-step, self-etching systems

Clearfil S3 Bond® (Kuraray), Ace All Bond SE® (Bisco), All Bond SE® (Bisco), Adper Easy Bond® (3M ESPE)

Multimode

Single Bond Universal® (3M ESPE), Clearfil Universal Bond® (Kuraray), Adhese Universal® (Ivoclar Vivadent), AllBond Universal® (Bisco), G-bond Plus® (GC)

TOTAL-ETCHING ADHESIVES The oldest group of adhesives consists of the total-etching conditioning systems, materials in which the component parts necessary for adhesion are separated: acid, primer and adhesive.30 They may require two or three steps, depending upon whether the primer is combined or not with the adhesive in one bottle, respectively, and where the acid from the etching step must always be isolated.2 In this etching strategy, dentin and enamel are treated with a phosphoric acid gel for the removal of smear layer and superficial demineralization of hydroxyapatite crystals. After this chemical conditioning, the resinous monomers (primer and adhesive) dissolved in an organic solvent are applied to infiltrate the etched substrates.25 PHOSPHORIC ACID Phosphoric acid, as previously discussed, is responsible for increasing the surface free energy of enamel and create microporosities in this dental substrate.1,18 After applying the acid on enamel, its surface should be completely dried and then the adhesive applied directly without any influence on the dry substrate during adhesion.28 In contrast, in dentin after rinsing of the acid, a layer of 1-10 μm3 of the surface mineral phase is completely removed, leaving the collagen fibrils literally suspended in water.28 Drying of this layer promotes collapsing of the collagen fibrils, which makes it virtually impervious to resin, as well as the excess water which also prevents penetration, ie, it is necessary to maintain an intermediate state of moisture to form the hybrid layer.9,28 A primer should be applied on dentin after the acid etching to increase its surface energy, since, in contrast to what occurs in enamel, the surface energy of dentin decreases after etching. Due to these characteristics, the type of solvent incorporated into the adhesive systems is an important factor when choosing the material to be used.25,28 PRIMER Primers are mainly formed by amphoteric monomers and solvents, and correspond to the second step of the total-etching adhesive systems with respect to dentin. Amphoteric monomers are those that have affinity for hydrophobic and hydrophilic substances; hydrophilic monomers enhance the wettability of the dental substrate, while the hydrophobic interact and polymerize with the adhesive, which is formed by hydrophobic monomers.27 The effectiveness of adhesives on dentin is enhanced by the addition of organic solvents with high vapor pressure to its chemical formulations; conforming to its application to the 365

dentin surface, the function of the solvent is to connect to the water present between the collagen fibrils and induce their increased evaporation, leaving open spaces, where the adhesive monomers should infiltrate to interlock with the collagen fibers.3,28 Acetone and ethanol are solvents most found in adhesive systems on the market today.3 Recent investigations have shown that high immediate dentin-composite resin bond strength values may be obtained for ethanol/water and acetone based systems provided that they are vigorously stirred on the surface of demineralized dentin. Contrary to what is reported in laboratory studies it is possible to achieve high bond strengths on dry demineralized dentin depending on the form of the application of the adhesive, since the mechanical force exerted on the dentin surface during the application of an adhesive may compress the collapsed collagen fibers like a sponge,and as pressure is relieved those fibers then expand and the adhesive solution penetrates into these regions.28 ADHESIVE The adhesive itself is the third part of the total-etching adhesive system and is composed primarily of hydrophobic and light curing monomers, which should penetrate dentin seeking for primer to form the hybrid layer. In enamel, since there is no moisture it should just penetrate microporosities formed by the acid etching. In addition, the current adhesives offer a complex mixture of initiators, inhibitors or stabilizers, solvents and filler particles.34 In this system, as mentioned, the adhesive may be available in a separate bottle or a bottle jointly together with the primer, which characterize the three-step, and the twostep  systems, respectively. They are the oldest adhesive systems and the most widely used and reliable bonding strategies.30 The bond strength achieved with three-step systems, however, is still higher than that obtained for the two-step, since there is the application of the hydrophilic primer before the hydrophobic adhesive. Research suggests that the last water resistant layer protects the adhesive interface from degradation processes arising from the sorption and solubility, especially over time.7,10,16 Research also shows that preparations with all of margins in enamel exhibit greater predictability and longevity of bonding with any of the total-etching adhesives, since this outer layer is capable of protecting bonding in dentin, which is far less predictable.7 There are a number of critical steps to be performed to achieve the desired adhesion with these total-etching adhesive systems,which may lead to contamination issues of the adhesive interface before cementation. Furthermore, the difficulty of achieving the most appropriate degree of moisture required for dentin penetration by the adhesive also contributes to the sensitivity of the application technique by the operator.18,30 Given these characteristics, studies have been made to seek simpler adhesives, easier to apply, practical and less sensitive to the work to be carried out by the operator for obtaining excellent results.

366

SELF-ETCHING ADHESIVES Multi-step adhesive systems have been on the market since the early 1990s and today are considered the gold standard of the dental adhesives. However, there was an increasing demand in the market for adhesive procedures for faster application and a more simplified technique, which led to the implementation of the self-etching strategy.33 The self-etching adhesive systems do not require the initial application of an acidic product, since they etch and penetrate simultaneously both enamel and dentin by means of infiltration and partial dissolution of the hydroxyapatite and smear layer, without rinsing, creating a hybrid layer incorporating minerals and products of the smear layer.2,9,10,25,30 The elimination of the rinsing step and merely partial removal of smear layer results in a less sensible, faster and less aggressive adhesive system, and even further reduces post-operative sensitivity.9,33 In the same manner, the total-etching adhesive systems, the self-etching systems are also divided in accordance with the number of steps in one-step or two-step systems, that is, if the adhesive agent is combined or separate from the primer, respectively. Two-step systems are characterized by the use of a self-etching acidic primer followed by the application of the adhesive.11 The one-step systems, in which the acid conditioner, primer and adhesive are in a single bottle, are very popular in clinical practice and are also called “all-in-one” adhesives.2,12,13,25,31 The elimination of the acid etching has as its main advantage ease of technique, due to elimination of the need for rinsing and the attempt of maintaining the moisture of dentin in the right measure for successful application of the primer as well as the adhesive.9,30 These adhesives are also classified according to their pH either as being intermediary (pH close to 2) or strong (pH less than 1); the strongest of which are able to form thick hybrid layers, some as thick as those obtained by phosphoric acid etching.11,17,31 In the context of the daily practice, intermediary adhesives are probably more sensitive to the variations of the substrate: denser smear layers, biofilm or any other form of change or that of surface contamination which may prevent the direct contact of the adhesive with the tooth structure and therefore hinder the effective adhesion to enamel and dentin.17 Those f self-etching adhesives ound to be strong are capable of forming resin “tags” in dentin while the intermediary ones only slightly demineralize the “smear plug” and infiltrate the tubules with resin, but in general the first feature generally presents the worst results of longevity and durability of bonding than that produced by the intermediaries.33 For demineralization to occur, self-etching systems containing aqueous solutions of acidic functional monomers, typically of phosphoric acid or carboxylic acid esters, with a pH higher than that of phosphoric acid gels are utilized by the total-etching systems.21 From one perspective, this high pH is advantageous, since dentin may quickly reduce the acidity of the applied primer which, after polymerization, is already neutralized.30 However, this low acidity results in extremely superficial demineralization compared to that which is obtained with phosphoric acid etching, especially in enamel.25,30,31 As a result the formation of a hybrid layer thinner than conventional systems occurs, though studies have shown that the most modern self-etching adhesives have bond strengths comparable to total-etching systems, showing that the adhesion is not entirely dependent on the thickness of the hybrid layer.9,30 In view of this characteristic, some self-etching adhesives have two diffe367

rent adhesive mechanisms: micromechanical bonding, dependent on the formation of the hybrid layer; and chemical bonding dependent upon the 10-methacryloyl-oxidecil di-hydrogen phosphate monomer (10-MDP).9 The functional monomer 10-MDP has the strong capacity of chemically interacting with the calcium of the residual hydroxyapatite located around the exposed collagen fibrils, which improves the bond strength of these adhesives to dentin and protects the collagen from the effects of degradation.5,9,12,17,19,24,31,34 The same acidic monomers inhibit the polymerization of dual curing or self-curing composites due to the elimination of the tertiary amines of the redox initiator system in the polymerization of these systems. As a result, the bond strength is dramatically reduced. Therefore, self-etching adhesives are not suitable for use with dual-curing or self-curing materials, only those of the non-acidic two-step adhesive systems may be used.10 These adhesives are highly hydrophilic, especially the one-step adhesives most of which contain a monomer called HEMA (hydroxyethyl methacrylate), which makes this bonding strategy susceptible to sorption and solubility processes when both come into contact with water from the external environment as well as with the water from dentin itself (nanoleakage).10,31 As a result, the swelling of the polymer facilitates the elution of monomeric hybrid layer, which may expose collagen fibers to be exposed to cleavage through endogenous proteases.24 In order to avoid this it is essential that there exists adequate penetration of the monomers of the adhesive agent within the tooth structure. In order for this to occur, its active application in multiple layers is a clinical maneuver that promotes deeper demineralization and penetration of the adhesive system, also resulting in higher bond strengths, being that the very thin adhesive layers are susceptible to inhibition of polymerization by oxygen.18,28 The literature is controversial about adhesion of self-etching systems to enamel, and some studies also consider it much lower when compared to the bonding achieved by the total-etching systems.8,25 To solve this problem, the authors have suggested roughening with burs prior to the application of the adhesive system12,14 or the selective etching of enamel.8,12,31 Both techniques pressupose one more clinical step, which eliminates the advantage offered by the self-etching system to provide a simplified technique for both structures, enamel and dentin. Furthermore, the use of an exclusively enamel etching is clinically very complex and must be performed with gels of a greater viscosity, to avoid contact with dentin, since the acid which was previously applied to this substrate generates detrimental effects on dentin bonding.16,31 Other authors have reported excellent clinical behavior of the self-etching two-step adhesives without any preliminary etching, reporting only small enamel defects and surface discoloration.9,26,32 These defects were defined as small, being that they were clinically irrelevant, so additional use of phosphoric acid on enamel was not considered critical by these authors.9 Two-step self-etching adhesive systems are still considered superior to the “all-in-one” systems.31 In clinical practice, therefore, the dentist needs to opt for a total-etching or a self-etching system, depending upon the particular clinical situation. Then begin the search for an adhesive that may be applied in both manners allowing for the professional to choose the most appropriate adhesive protocol for each clinical situation with a single product.12

368

MULTIMODE ADHESIVES Recently, a new generation of adhesives was launched in the market based on a single vial that may be used as a total-etch, in combination with prior etching which utilizes phosphoric acid, such as self-etching or with the selective etching of enamel. Who decides on the method of application is the dentist, based on the characteristics of the substrate to be conditioned and the restoration to be performed. This new generation is called the multimode or universal adhesives.22 Its adhesion to dentin is quite favorable, since it is not necessary to be concerned with dentin moisture, because there is no etching of this substrate; there is merely the formation of a small hybrid layer, characteristic of the self-etching adhesives, from which adhesion is not entirely dependent.12,15 Bonding to this system is favorable because some of the multimode adhesives, as well as certain examples of self-etching adhesives, have the acidic monomer 10-MDP within their composition, providing chemical bonding to dentin.12,16,19,23 Bonding of 10-MDP to calcium creates a calcium-MDP salt which is one of the most hydrolytically stable salts which protects the adhesive layer from degradation.16,18 In addition, one of the trademarks (Single Bond Universal®, 3M ESPE, USA), also contains poly-alkenoic copolymers, found in the glass ionomer cement Vitrebond® (3M ESPE, USA), which may promote chemical bonding to the calcium present in the hydroxyapatite. However, some authors report that this copolymer may compete with the 10-MDP for hydroxyapatite, hampering the bond strength of these adhesives.12,16,18,22,23 In addition, these monomers have a high molecular weight and may hinder the approach of the monomers during polymerization, resulting in a lower degree of conversion.18 Performing phosphoric acid etching in dentin towards the use of a universal adhesive is not indicated, since this may impair the potential of chemical bonding potential between the phosphate and acidic monomers, by removing most of the calcium, responsible for this process.5,15,23,31 For its use in enamel, however, etching is still recommended as a means to achieve the best results.5,12,23 Although the 10-MDP monomer interacts with hydroxyapatite, apparently the size and organization of hydroxiapatite within enamel disfavors the connection to this substrate.5 The benefits of such selective etching may become evident only after a few years, through observation of the marginal integrity of the restorations fabricated with these adhesives.16 Active application of the adhesive is carried out with movements of a disposable brush for 15 seconds may also increase the bond strength by the improved penetration of the adhesive and deeper etching of the substrate.5,12,23 Its use, just like the self-etching adhesives is only indicated for restorations with a minimal amount of enamel, for those restorations where the aaesthetic demand is less critical and in sites where there exist a high risk of application error (poor access, inadequate isolation of the operative field, minimal time and poor patient cooperation, as is often the case with children, the elderly and patients with special needs). Therefore, for those restorations requiring strong adhesion to enamel or with great aesthetic demand, prior enamel etching should be performed, as it may be possible to increase the bond strengths by 50%.12 All of the universal or multimode adhesives are simplified adhesives: whether they are self-etch, or one-step adhesives; or total-etch, ie, two-step adhesives. This feature, combined with good mechanical retention results up until the present, is already enough for its 369

indication.22,23 However, longitudinal clinical studies with long-term follow-ups of restorations carried out using this adhesive system are required for its consecration when faced up

to trademarks, but remember that the characteristics that should always be the goal of each and every adhesive system. When researchers are able to develop an adhesive system of easy clinical application which promotes increased surface free energy, creates mechanical micro-retentions, adequately penetrates the substrate without biological damage and promotes suitable bond strengths over time, it will be possible to consider that the ideal adhesive system was reached, combining durability, biocompatibility and longevity.

We express our sincere thanks to Professor Sillas Duarte and Professor Neimar Sartori, for their fundamental collaboration in preparing the SEM micrographs presented in this chapter. Impossible for the human eye, the exploration of the microscopic world made the study and the practice of dentistry a magical, sound and an absolute concrete routine. Therefore, our eternal gratitude to Professor Sillas and Professor Neimar, for what that they have done, do and will do for worldwide Dentistry!

370

ACKNOWLEDGEMENTS

Ideally, in search of the perfect adhesive system, the dentist should not be directed

CONCLUSION

against the many adhesives that we have on the market.

REFERENCES

1. Buonocore M. A Simple method of increasing the adhesion of acrylic filling materials to enamel surfaces. J Dent Res. 1955;34:849-53. 2. Cardoso MV, de Almeida Neves A, Mine A, Coutinho E, Van Landuyt K, De Munck J, et al. Current aspects on bonding effectiveness and stability in adhesive dentistry. Aust Dent J. 2011;56(1):31-44. 3. Cardoso PC, Lopes GC, Vieira LC, Baratieri LN. Effect of solvent type on microtensile bond strength of a total-etching one-bottle adhesive system to moist or dry dentin. Oper Dent. 2005;30(3):376-81. 4. Carvalho RM, Manso AP, Geraldeli S, Tay FR, Pashley DH. Durability of bonds and clinical success of adhesive restorations. Dent Mater. 2012;28(1):72-86. 5. De Goes MF, Shinohara MS, Freitas MS. Performance of a new one-step multi-mode adhesive on etched vs non-etched enamel on bond strength and interfacial morphology. J Adhes Dent. 2014;16(3):243-50. 6. De Munck J, Mine A, Van den Steen PE, Van Landuyt KL, Poitevin A, Opdenakker G, et al. Enzymatic degradation of adhesive-dentin interfaces produced by mild self-etching adhesives. Eur J Oral Sci. 2010;118(5):494-501. 7. De Munck J, Van Meerbeek B, Yoshida Y, Inoue S, Vargas M, Suzuki K, et al. Four-year water degradation of total-etching adhesives bonded to dentin. J Dent Res. 2003;82(2):136-40. 8. Erickson RL1, Barkmeier WW, Latta MA. The role of etching in bonding to enamel: a comparison of self-etching and etch-and-rinse adhesive systems. Dent Mater. 2009;25(11):1459-67. 9. Ermis RB, Kam O, Celik EU, Temel UB. Clinical evaluation of a two-step etch&rinse and a two-step self-etching adhesive system in Class II restorations: two-year results. Oper Dent. 2009;34(6):656-63. 10. Haller B. Which self-etching bonding systems are suitable for which clinical indications? Quintessence Int. 2013;44(9):64561. 11. Hamouda IM, Samra NR, Badawi MF. Microtensile bond strength of etch and rinse versus self-etching adhesive systems. J Mech Behav Biomed Mater. 2014(3):461-6. 12. Hanabusa M, Mine A, Kuboki T, Momoi Y, Van Ende A, Van Meerbeek B, et al. Bonding effectiveness of a new ‘multi-mode’ adhesive to enamel and dentine. J Dent. 2012;40(6):475-84. 13. Ito S, Tay F, Hashimoto M, Yoshiyama M, Saito T, Brackett WW, Waller JL, et al. Effects of multiple coatings of two all-in-one adhesives on dentin bonding. J Adhes Dent. 2005;7:133-41. 14. Kanemura N, Sano H, Tagami J. Tensile bond strength to and SEM evaluation of ground and intact enamel surfaces. J Dent. 1999;27:523-30. 15. Marchesi G, Frassetto A, Mazzoni A, Apolonio F, Diolosà M, Cadenaro M, et al. Adhesive performance of a multi-mode adhesive system: 1-year in vitro study. J Dent. 2014;42(5):603-12. 16. Mena-Serrano A1, Kose C, De Paula EA, Tay LY, Reis A, Loguercio AD, et al. A new universal simplified adhesive: 6-month clinical evaluation. J Esthet Restor Dent. 2013;25(1):55-69. 17. Mine A1, De Munck J, Cardoso MV, Van Landuyt KL, Poitevin A, Kuboki T, et al. Bonding effectiveness of two contemporary self-etching adhesives to enamel and dentin. J Dent. 2009;37(11):872-83. 18. Muñoz MA, Luque I, Hass V, Reis A, Loguercio AD, Bombarda NH. Immediate bonding properties of universal adhesives to dentine. J Dent. 2013;41(5):404-11. 19. Muñoz MA, Luque-Martinez I, Malaquias P, Hass V, Reis A, Campanha NH, et al. In vitro longevity of bonding properties of universal adhesives to dentin. Oper Dent. 2015;40(1). 20. Nakabayashi N, Kojima K, Masuhara E. The promotion of adhesion by the infiltration of monomers into tooth substrates. J Biomed Mater Res. 1982;16:265-73. 21. Pashley DH, Tay FR. Aggressiveness of contemporary self-etching adhesives. Part II: Etching effects on unground enamel. Dent Mater. 2001;17:430-44. 22. Perdigão J, Kose C, Mena-Serrano AP, De Paula EA, Tay LY, Reis A, et al. A new universal simplified adhesive: 18-month clinical evaluation. Oper Dent. 2014;39(2):113-27. 23. Perdigão J, Loguercio AD. Universal or multi-mode adhesives: why and how? J Adhes Dent. 2014;16(2):193-4. 24. Perdigão J, Reis A, Loguercio AD. Dentin adhesion and MMPs: a comprehensive review. J Esthet Restor Dent. 2013;25(4):219-41. 25. Perdigão J. New developments in dental adhesion. Dent Clin North Am. 2007;51(2):333-57, viii. 26. Peumans M, De Munck J, Van Landuyt K, Lambrechts P, Van Meerbeek B. Three-year clinical effectiveness of a two-step self-etching adhesive in cervical lesions. Eur J Oral Sci. 2005;113:512-8. 27. Reis A, Carrilho M, Breschi L, Loguercio AD. Overview of clinical alternatives to minimize the degradation of the resin-dentin bonds. Oper Dent. 2013;38(4):E1-E25. 28. Reis A, Pellizzaro A, Dal-Bianco K, Gones OM, Patzlaff R, Loguercio AD. Impact of adhesive application to wet and dry dentin on long-term resin-dentin bond strengths. Oper Dent. 2007;32(4):380-7. 29. Tjäderhane L, Nascimento FD, Breschi L, Mazzoni A, Tersariol IL, Geraldeli S, et al. Strategies to prevent hydrolytic degradation of the hybrid layer - A review. Dent Mater. 2013;29(10):999-1011. 30. Tyas MJ, Burrow MF. Adhesive restorative materials: a review. Austr Dent Journal. 2004;49:(3):112-21. 31. Van Landuyt KL, Peumans M, De Munck J, Lambrechts P, Van Meerbeek B. Extension of a one-step self-etching adhesive into a multi-step adhesive. Dent Mater. 2006;22(6):533-44. 32. Van Meerbeek B, Kanumilli P, De Munck J, Van Landuyt K, Lambrechts P, Peumans M. A randomized controlled study evaluating the effectiveness of a two-step self-etching adhesive with and without selective phosphoric-acid etching of enamel Dent Mater. 2005;21:375-83. 33. Van Meerbeek B, Yoshihara K, Yoshida Y, Mine A, De Munck J, Van Landuyt KL. State of the art of self-etching adhesives. Dent Mater. 2011;27(1):17-28. 34. Yoshida Y, Inoue S. Chemical analyses in dental adhesive technology. Japan Dent Sci Rev. 2012;48:141-52. 35. Yoshida Y, Yoshihara K, Nagaoka N, Hayakawa S, Torii Y, Ogawa T, et al. Self-assembled Nano-layering at the adhesive interface. J Dent Res. 2012;91(4):376-81.

371

chapter 11

resin cements Ana Paula Rodrigues de Magalhães | Paula de Carvalho Cardoso

function is to fill the small spaces between the preparation and the indirect restoration and hold the restoration chemically, mechanically or micromechanically to the tooth, preventing displacement during function.13,18 In Dentistry, three basic types of luting cements are available: conventional or non adhesive cements (e.g., zinc phosphate); chemical bonding cements (glass ionomer cements); and micromechanical bonding cement (resin cements).4,10 Resin cements have a very similar composition to that of restorative resins and are formed by a resin matrix with inorganic fillers treated with silane. However, they differ from composite resins by the lower filler loading and lower viscosity, allowing for better flow.22 Resin cements are, in most cases, the cement of choice for luting ceramic restorations for having superior mechanical, physical and adhesive properties when compared to other conventional cements and due to their versatility.13,14,16,20 They provide adequate stability in the oral environment with low solubility, high bond strengths and greater resistance to fracture than cemented ceramic restoration, in addition to producing excellent aaesthetic results.1,13,14,16,17 The integration between ceramic and cement through adhesive processes promotes retention of the restoration; reinforces both substrates, tooth and restoration, providing them with mechanical support; seals the tooth-restoration interface, reducing microleakage; seals the dentinal tubules; and collaborates with aaesthetics.2,4,26 Adhesion of these resin cements is so predictable that the reduction of healthy tooth structure in order to promote physical and/or mechanical retention becomes unnecessary, making preparations minimal or nonexistent, preserving a greater amount of healthy tooth structure and pulpal health.7 Some disadvantages of these cements include higher cost, technical sensitivity and difficulty of removing proximal excess.4,22 Since there are no ideal luting agents, which have an outstanding performance in the myriad of existing clinical conditions, these cements are available on the market with the most diverse characteristics, seeking to satisfy each of these situations with different compositions, shades, polymerization reactions, viscosities and bonding systems, which influence their physical properties, handling and bond strengths.4,6 The different shades of resin cements exist to allow them to adapt to the various shades of tooth substrates and ceramics, giving the dentist the option of selecting the ideal shade to obtain the desired aaesthetics in each case.1,3 Several studies have examined the influence of the shade of the resin cement on the final shade of the ceramic veneer, and they all have shown a strong influence, especially in thinner ceramic restorations.1,3,19,20,21,27 About the adhesive properties, resin cements may be conventional, when bonding to the dental substrate is dependent on the previous application of an adhesive system; or self-adhesives, which dispense the application of any bonding agent to the dental substrate. Cements may also be classified according to polymerization systems in self-curing cements, ie, cements dependent upon a chemical reaction to polymerize; light cured, or light dependent; or double polymerization or dual, using both reactions10 (Figure 1). Since most aaesthetic restorations require adhesive cementation and therefore ne374

ADHESIVE LUTING

Cement is a substance that yields a sound bond between two surfaces. Its primary

cessitate a number of steps in the process of obtaining clinically successful adhesion, the dentist must understand the application and mode of use of each different resin cements for their proper selection in the pursuit of producing restorations that meet aaesthetics, predictability and longevity.

CLASSIFICATION Resin Cements

Conventional • Self-curing • Dual

• Light-curing

Self-Adhesive

• Dual

Figure 1.

CONVENTIONAL RESIN CEMENTS

Figure 1. Classification of resin cements.

Conventional resin cements are those that rely on the entire process of the adhesive system to adhere to the dental substrate, either by the self-etching or total-etching technique. Because of the number of steps, the technique is very sensitive to the operator and susceptible to errors throughout the process.2,10 They are the oldest cement on the market as well as the most used due to their proven effectiveness and because of the greater confidence of professionals in the conventional adhesive systems. The polymerization reaction depends on free radicals to occur and may, in the case of conventional resin cements, be initiated by a redox chemical reaction, which characterizes a cement which is chemically activated; by light, in a light-curing cement; or by both reactions, corresponding to the dual cements. CONVENTIONAL SELF-CURING RESIN CEMENTS The polymerization reaction of self-curing resin cements is completely chemical, ie it is independent of light to take place (Figure 2). These cements are the oldest, their use implies the mixture of two pastes, base and catalyst which, when mixed, initiate a polymerization reaction. This reaction is dependent upon an aromatic tertiary amine, which ensures that the polymerization reaction is complete on every level of depth of the preparation and under every thickness of the restorative material. However, amine degrades over time, it produces discoloration of the resin cement, which when used on very thin restorations, influences its color.15,20 This implies that using such cements requires a limited working time, since the reaction takes place independently of the will of the operator. They are indicated 375

Figure 2.

Figure 3.

Figure 2. Self-curing resin cement (Multilink N®, Ivoclar Vivadent, Liechtenstein). Figure 3. Base paste of the dual curing resin cement (Variolink II®, Ivoclar Vivadent, Liechtenstein).

in cases where it is not possible to obtain the penetration of light necessary for the highest possible degree of polymer conversion, as, for example, in metal-ceramic crowns, very thick ceramics, metal cores and in situations where the restoration is not influenced by the shade of the substrate or the cement.4,10 CONVENTIONAL DUAL RESIN CEMENTS Dual polymerization or dual resin cements combine the desirable characteristics of a light-curing cement and a chemical cement (Figures 3 and 4). Besides the advantage of the chemical reaction of those monomers located in the deeper areas where light intensity is lower, dual resin cements have been shown to have superior mechanical properties due to the higher degree of conversion achieved by such cements, exhibiting a higher flexural strength as well as modulus of elasticity and hardness when compared to the light-curing or self-curing cements.3,10 These cements have been shown to exhibit a broad application for luting ceramic crowns when the amount of light required for polymerization throughout every region of the cement may not be obtained, since chemical polymerization is able to complement the reaction in regions where the light did not penetrate (Figures 11 to 15). Although their superior properties are guaranteed with an efficient curing from light sources which are able to provide large amounts of energy.12,14 These cements are also obtained from mixing base and catalyst pastes, and like self curing cements,also contain aromatic tertiary amine in their formulation, generating oxidation products which may compromise the color stability of the cemented restoration over time and are therefore contraindicated for use with veneers.3,24 These cements also do not have a wide range of shades from the majority of manufacturers, which decreases the dentist’s ability of combining the veneer shade with the other teeth through the use of 376

Figure 4.

Figure 5.

Figure 4. Catalyst paste of the dual cure resin cement (Variolink II®, Ivoclar Vivadent, Liechtenstein). Figure 5. Dual-cure cement RelyX Ultimate® (3M ESPE, USA).

the cement. In addition, they do not offer try-in colored pastes, which also restricts their usage when it comes to very thin veneers. In addition, their working time and degree of flow increases the difficulty of their use and limits their indication.8 Some authors have attempted to merely utilize the base paste without the catalyst, of some dual cements to obtain a light-curing cement to eliminate the undesirable effect of the tertiary amine, however, despite the favorable results, this is not the primary indication of the manufacturer, and the best aforementioned properties of the cement are obtained by mixing both pastes.3,20 Even with satisfactory aaesthetic outcomes, the use of base pastes is difficult due to the lower degree of flow and a lower viscosity, especially when it comes to ceramic veneers without wear or “contact lenses”. Therefore, due to its minimal thickness, the ceramic may fracture due to the need for greater digital pressure to be imposed for the proper seating on the substrate, considering that these pastes are thicker. It is recommended that resin cements are used with adhesive systems of the same polymerization method, for the purpose of not having to compromise with undesirable chemical reactions between products. In addition, dual cements should not be used with self-etching one-step systems due to adverse chemical interaction between the acidic monomers from the most superficial layer of the adhesive, not being completely polymerized as well as the aromatic amine resin of the dual cement.10,11 A new dual cement promises to be indicated for luting ceramic veneers, RelyX Ultimate® (3M ESPE, USA) (Figure 5). According to the manufacturer, this cement does not depend on the aromatic tertiary amine for its polymerization, but contains another component which accomplishes the same function, giving it color stability over time. Furthermore it offers try-in pastes for shade testing before cementation, a feature previously found only in light-curing cements. Studies need to be made to clinically observe the actual performance of the cement prior to its safe indication for use in ceramic veneers. 377

CONVENTIONAL LIGHT-CURING RESIN CEMENTS Light-cured resin cements are those whose polymerization reaction is initiated by the application of visible light (Figure 6). The main advantages of these cements are the greatest working time and color stability.3,4 They are very suitable for veneers, contact lenses and ceramic fragments because their color influences the final shade of the restoration (Figure 16), and present a variety of colors and different degrees of opacity, with the corresponding shaded try-in pastes, for verifying the result before cementation3,7,13 (Figure 7). In addition, light-curing resin cements have greater color stability when compared to dual and self-curing resin cements, due to the absence of the aromatic tertiary amine.3 Even more, light-curing cements enable minor thicknesses of the cementation film by its high flow and excellent degree of viscosity, which facilitates the removal of excess and shortens the finishing time after the cementation.3,8,23 Bonding of these cements to ceramic is strongly influenced by the degree of polymerization, the modulus of elasticity, the shade and the thickness of the cement. Despite its good properties, light-curing cement is not indicated for very thick or slightly translucent veneers or crowns due to the difficulty of light passage, and therefore in these cases the cement will not reach an optimal degree of conversion, affecting its mechanical properties as well as its adhesion.1,22 Low-viscosity and thermoplasticized composites are widely indicated and used for luting prostheses,9 although our ABO-GO Dentistry Team is convinced about the precise indication of using light-cured resin cements for luting ceramic veneers. Even with a lot of clinical experience, it is virtually impossible for the dentist to predict the final outcome, especially in the case of ceramic veneers without reduction, whenever using a resin without carrying out a preliminary shade try-in; a condition prevented by the protocol which utilizes low-viscosity or thermoplasticized resins.

Figure 6.

Figure 7.

Figure 6. Light-curing resin cements (Variolink Veneer®, Ivoclar Vivadent, Liechtenstein). Figure 7. Shaded try-in light-curing resin cement pastes (Variolink Veneer®, Ivoclar Vivadent, Liechtenstein).

378

DUAL SELF-ADHESIVE RESIN CEMENTS

The self-adhesive resin cements can adhere to any tooth substrate without the application of an acid or adhesive. Their application is complete in just one step, making them clinically appealing, since they eliminate the limitations and risks of a complex conventional bonding technique while minimizing postoperative sensitivity2,10,22 (Figures 8 to 10). Despite their low pH (pH