Bruxism: Theory and Practice

Bruxism: Theory and Practice Editor: Daniel A. Paesani Contributors: Monica Andersen, Taro Arima, Lene Baad-Hansen, Marta M. Barreiro, Gunnar E. Carls...
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Bruxism: Theory and Practice Editor: Daniel A. Paesani Contributors: Monica Andersen, Taro Arima, Lene Baad-Hansen, Marta M. Barreiro, Gunnar E. Carlsson, Fernando Cifuentes, Sergio Fuster, Jorge Mario Galante, Carlos Gianoni, Fernando Goldberg, Hans L. Hamburger, Faramarz Jadidi, Anders Johansson, Ann-Katrin Johansson, Takafumi Kato, Marcelo Kreiner, Stephanos Kyrkanides, Frank Lobbezoo, Ricardo L. Macchi, Daniele Manfredini, Arturo E. Manns Freese, Machiel Naeije, Luca Guarda Nardini, Ridwaan Omar, Claudia Restrepo, Xiomara Restrepo-J., Andres R. Sanchez, Guillermo Schinini, Teresa Cristina Barros Schütz, José T. T. de Siqueira, Peter Svensson, Ross H. Tallents, Sergio Tufik

London, Berlin, Chicago, Tokyo, Barcelona, Beijing, Istanbul, Milan, Moscow, New Delhi, Paris, Prague, São Paulo, Seoul, and Warsaw

Foreword For years the dental profession has been intrigued, fascinated, and sometimes even obsessed with the phenomenon we call bruxism. It has been underdiagnosed, overdiagnosed, and even misdiagnosed. Some have described it as the most destructive process affecting the masticatory structures, while others refer to it as a benign routine activity. Some suggest it is rare, while others say it is very common. Some say it is a major contributor to temporomandibular disorders, while others say it is not even related. The etiology of bruxism has been hotly debated for years. Some believe it is a peripherally generated activity associated with tooth contacts, while others believe it is a central brainstem-driven process. There is a long list of suggested causes of bruxism such as eccentric tooth contacts, dental malocclusion, emotional stress, anxiety, sleep disturbances, genetic factors, medications, alcohol consumption, breathing disorders, allergies, mental disorders, and even pin worms. Bruxism is even mentioned in the Holy Bible as the “gnashing of teeth” associated with anger and frustration. The dental profession has learned that studying bruxism is difficult and controversial. Most patients are unaware of their bruxing activity and therefore deny it. Bed partners are sometimes more reliable reporters. We dentists seem to inform all our patients that they brux; they just don’t know it. We most probably do this because we see the evidence of tooth wear, yet timing may be a serious issue. For instance, significant tooth wear in a 40-year-old patient may present as a dental problem; yet this

wear might have occurred 20 years earlier and bruxism is no longer a contributing factor. Clinicians have also developed a wide variety of treatments for bruxism, many with no scientific evidence. Dental treatments have ranged from selectively adjusting the occlusion to prosthetic or orthodontic therapies. We have developed a wide variety of occlusal appliances, most with limited to no supportive data. We have suggested non-dental therapies such as medications, biofeedback, stress reduction, and acupuncture. We have even used negative-feedback devices including electric shocks, loud noises, and taste aversion. It is obvious that we need to understand and document the most effective method to manage bruxism. It is quite evident that the profession needs a comprehensive review of this complex phenomenon known as bruxism. Dr. Daniel Paesani recognized this need and has put together the most thorough body of information ever created by the profession. He has assembled some of our finest experts from around the world to contribute their knowledge and insights to this text. His comprehensive list of chapters has left no stone unturned. This text is the most complete overview of bruxism the profession has ever had opportunity to review. There are several reasons why I am very pleased to have been asked to write the foreword to this textbook. First, this text represents the first comprehensive attempt to review bruxism, and the profession needs to be enlightened and informed about this important subject. I am also very pleased V


because I have known Daniel Paesani for almost 30 years and I know and appreciate his dedication to the field. Dr. Paesani was one of my very first international residents in our Orofacial Pain Center and he came from Rosario, Argentina to Lexington, Kentucky with much passion for the field and personal sacrifice. I have always admired his dedication and work ethic, and this text is a


product of just that. I believe it will serve our profession well. Jeffrey P. Okeson, DMD Chair, Department of Oral Health Science Director, Orofacial Pain Program University of Kentucky College of Dentistry Lexington, Kentucky, USA

Preface and Acknowledgments

Over my 12 years as Professor of Masticatory System Physiology in the School of Odontology of the Universidad del Salvador/AOA (Buenos Aires, Argentina), the biggest problem we have had to face has been the lack of scientific compilations on bruxism, which are needed for students to take bruxism as an object of study. At first, we used to request students to visit the Medline web page – the most important biomedical-literature database worldwide – and perform searches, but before long we realized that was not the right track. The students faced the difficulty of having to select which pieces of information to use from the thousands of publications retrieved by search engines. Of course, since these were first-degree students, they were not yet sufficiently qualified to differentiate concepts that had been validated by scientific method from concepts based simply on mysticism and dogma. We, the professors, would spend long hours assisting them with these issues, and we would use the scarce, precious time available to us to select and compile the study material rather than to teach. This experience made me wonder why – researchers and published books being so many and bruxism being such an important entity in the odontological field – not a single volume existed devoted exclusively to bruxism. When I found no answer to this question, I started to think about taking on the responsibility to compile information with the aim of publishing a volume exclusively devoted to bruxism and its treatment.

After preparing an extensive list of chapters, and with the purpose of addressing all the topics related to bruxism, I invited a group of colleagues whose brilliant professional careers, experience, and dedication to the subject would a priori guarantee their addressing the specific topics with scientific and scholarly rigor. The premise was that each paragraph, each idea, each suggestion should be based on scientific evidence, so that the work, apart from being useful to college professors and students, is an interesting book for general practitioners, one that provides answers to the many questions arising in everyday dental practice. Also, specialists in craniomandibular disorders will benefit from the in-depth analysis of the subjects and the extensive, up-to-date bibliographies contained herein, which provide a quick, well-organized way to access the evidence they need in their professional practice and as a tool for planning future research. So, the volume is divided into three sections. • The first section comprises eight chapters dealing with bruxism knowledge and guidelines for diagnosis, sleep physiology, main etiological theories, influence of peripheral and emotional factors, movement disorders, and bruxism in children. • The second section comprises nine chapters and is devoted to the effects of bruxism on the masticatory system components. Some of the topics are: the noxious action of bruxism on dental pulp, periodontal ligament, temporomandibular joints, muscles, and its relationVII

Preface and Acknowledgments

ship with pain. Some bruxism effects that are currently controversial are discussed, for which purpose a wide review of the literature on the subject is provided. Special emphasis has been placed on tooth wear and on the differential diagnosis of bruxism’s several causes. One chapter has been specifically devoted to dental erosion, and another chapter to endogenous erosion mechanisms, since general practitioners often mistake tooth wear caused by endogenous erosion for tooth wear caused by bruxism. • The third section comprises eight chapters and deals with various aspects related to the treatment of bruxism. The pharmacological effects of certain central-action drugs and some peripheral-action drugs, such as botulinum toxin, are described. The text also deals with the treatment of bruxism involving dental implants and appliances constructed with dental materials particularly recommended for bruxers. Topics related to dental occlusion are discussed with the aim of facilitating understanding of the concepts needed to enter the fascinating world of complex oral rehabilitation. One chapter deals with techniques used for the reconstruction of teeth affected by significant wear. The volume also includes a review of the scientific evidence on the treatment of bruxism, especially bruxism splints. The different procedures used for protecting the masticatory system against the effects of bruxism are described and illustrated by means of case reports.


Acknowledgments I would like to express my gratitude to: • the contributing authors, whose valuable expertise and thorough dedication ensured the excellent coverage of a wide range of topics related to bruxism • Professors Jeffrey Okeson, Ross Tallents, Per-Lennart Westesson, and Annika Isberg for introducing me to the marvelous world of science • Quintessence Publishing for believing in this book and accepting it for publication • professional translators Ángela Giottonini (Chapters 1, 15, and 21) and María Mirela Perusia (Chapters 2, 9–14, 20, 23, and 25) for their brilliant translations of the original Spanish text into English • Valeria Castillo for proofreading the original Spanish text • the staff of the library of the Asociación Odontológica Argentina (Dental Association of Argentina) for their valuable help in obtaining the innumerable bibliographical references I have used • my assistants Liliana Rivalta, Gabriela Allo, and Patricia Peloso for their endless patience and dedication and their invaluable help in the management of the numerous patients and in the process of obtaining the clinical photographs • my family, Triana, Guido, Julia, Pedro, Susana, and Candela, who, in all their love, gave up sharing many irretrievable days with me. Daniel Angel Paesani Editor

List of all contributors Editor Daniel A. Paesani, DDS Professor of Stomatognathic Physiology School of Dentistry University of Salvador/AOA Buenos Aires, Argentina

Marta M. Barreiro, DDS, Dr Dent Professor of Dental Materials School of Dentistry University of Buenos Aires Buenos Aires, Argentina

Monica Andersen, PhD Associate Professor Department of Psychobiology School of Medicine Universidade Federal de São Paulo (UNIFESP) São Paulo, Brazil

Gunnar E. Carlsson, LDS, Odont Dr/ PhD, Dr Odont hc, Dr Dent hc, FDSRCS Professor Emeritus Department of Prosthetic Dentistry/ Dental Materials Science Specialist in Prosthodontics and TMD/ Orofacial Pain Institute of Odontology The Sahlgrenska Academy University of Gothenburg Göteborg, Sweden

Taro Arima, DDS, PhD Assistant Professor Department of Oral Rehabilitation Graduate School of Dental Medicine University of Hokkaido Sapporo, Japan

Fernando Cifuentes, DDS Assistance Professor Department of Stomatognatic Physiology School of Dentistry University of Salvador/AOA Buenos Aires, Argentina

Lene Baad-Hansen, DDS, PhD Associate Professor Department of Clinical Oral Physiology School of Dentistry Aarhus University Aarhus, Denmark

Sergio Fuster, MD Gastroenterology Specialist Private Practice, Rosario, Argentina


Jorge Mario Galante, DDS Associate Professor School of Dentistry University of Buenos Aires Buenos Aires, Argentina IX

List of all contributors

Carlos Gianoni, MD Gastroenterology Specialist Private Practice Rosario, Argentina Fernando Goldberg, DDS, PhD Professor Department of Endodontics School of Dentistry University of Salvador/AOA Buenos Aires, Argentina Hans L. Hamburger, MD, PhD Neurologist Department of Clinical Neurophysiology Amsterdam Center for Sleep-Wake Studies Slotervaart Hospital Amsterdam, The Netherlands Faramarz Jadidi PhD student Department of Clinical Oral Physiology School of Dentistry, Aarhus University Aarhus, Denmark Anders Johansson, DDS, Odont Dr/PhD Professor Department of Clinical Dentistry - Prosthodontics Specialist in Prosthodontics and TMD/ Orofacial Pain Faculty of Medicine and Dentistry University of Bergen Bergen, Norway Ann-Katrin Johansson, DDS, Odont Lic/MSc, Odont Dr/PhD Associate Professor and Head of Cariology Department of Clinical Dentistry - Cariology Specialist in Pediatric Dentistry Faculty of Dentistry, University of Bergen Bergen, Norway


Takafumi Kato, DDS, PhD Associate Professor Institute for Oral Science Graduate School of Oral Medicine Matsumoto Dental University Chief Dental Sleep Medicine Clinic Matsumoto Dental University Hospital Matsumoto, Japan Marcelo Kreiner, DDS Professor and Chairman Department of General and Oral Physiology School of Dentistry Universidad de la República Montevideo, Uruguay Stephanos Kyrkanides, DDS, MS, PhD Professor and Chairman Department of Orthodontics and Pediatric Dentistry School of Dental Medicine Stony Brook University Stony Brook New York, NY, USA Frank Lobbezoo, DDS, PhD Professor Department of Oral Function Academic Centre for Dentistry Amsterdam (ACTA), Amsterdam, The Netherlands Ricardo L. Macchi, DDS, MS, Dr Dent Professor Emeritus of Dental Materials School of Dentistry University of Buenos Aires Buenos Aires, Argentina Daniele Manfredini, DDS Visiting Professor TMD Clinic Department of Maxillofacial Surgery University of Padova, Padova, Italy

List of all contributors

Arturo E. Manns Freese, DDS, PhD Professor of Oral Physiology and Occlusion School of Dentistry, University of the Andes Santiago, Chile Machiel Naeije, PhD Professor and Chair Department of Oral Function Academic Centre for Dentistry Amsterdam (ACTA), Amsterdam, The Netherlands Luca Guarda Nardini, MD, DDS Director TMD Clinic, Department of Maxillofacial Surgery University of Padova, Padova, Italy Ridwaan Omar, BSc, BDS, LDSRCS, MSc, FRACDS, FDSRCSEd Professor and Head of Prosthodontics Vice Dean for Academic & Clinical Affairs Department of Restorative Sciences Faculty of Dentistry, Kuwait University Kuwait

Guillermo Schinini, DDS Clinical Assistant Professor Department of Periodontology Maimonides University Private Practice Rosario, Argentina Teresa Cristina Barros Schütz, DDS, PhD Researcher Department of Psychobiology School of Medicine Universidade Federal de São Paulo (UNIFESP) São Paulo, Brazil José T. T. de Siqueira, DDS, PhD Head of Orofacial Pain Team Dentistry Division Hospital das Clínicas, School of Medicine Universidade de São Paulo (USP) Researcher Department of Psychobiology School of Medicine Universidade Federal de São Paulo (UNIFESP) São Paulo, Brazil

Claudia Restrepo, DDS Pediatric Dentist Teacher, Postgraduate Program of Pediatric Dentistry and Preventive Orthodontics Director of the CES-LPH Research Group CES University, Medellin, Colombia

Peter Svensson, DDS, PhD, Dr Odont Professor Department of Clinical Oral Physiology School of Dentistry, Aarhus University Aarhus, Denmark

Xiomara Restrepo-J., DDS General Practice Resident Department of General Dentistry Eastman Institute for Oral Health Rochester, NY, USA

Ross H. Tallents, DDS Professor of Dentistry Department of Orthodontics and Prosthodontics Eastman Institute for Oral Health Rochester, NY, USA

Andres R. Sanchez, DDS, MS Private Practice, Eden Prairie, MN, USA Former Assistant Professor in Periodontics Marquette University School of Dentistry Milwaukee, WI, USA

Sergio Tufik, MD, PhD Professor Department of Psychobiology School of Medicine Universidade Federal de São Paulo (UNIFESP) São Paulo, Brazil XI

Contents PART 1: OVERVIEW OF THE PROBLEM Chapter 1 - Introduction to Bruxism 3 Daniel A. Paesani Introduction 3 The Importance of Bruxism in Daily Care 3 Oral Habits 4 Classification of Bruxism according to the Type and Timing of Activity Etiology 5 Genetics 5 Epidemiology 10 Bruxism Variability 15 References 15 Chapter 2 – Diagnosis of Bruxism 21 Daniel A. Paesani Introduction 21 Clinical Diagnosis 22 Complementary Methods for Diagnosis References 38



Chapter 3 – Sleep Physiology and Bruxism 41 José T. T. de Siqueira, Teresa Cristina Barros Schütz, Monica Andersen, and Sergio Tufik Introduction 41 Basic Facts of Sleep Physiology and Pathophysiology 42 Sleep Architecture 44 The Sleep Laboratory 47 Understanding Bruxism in a PSG 47 Conclusion 50 References 51



Chapter 4 – Etiology of Bruxism 53 Frank Lobbezoo, Hans L. Hamburger, and Machiel Naeije Introduction 53 Categories 55 Morphologic Factors 55 Psychosocial Factors 57 Pathophysiologic Factors 58 Conclusion 61 References 62 Chapter 5 – Role of Peripheral Sensory Factors in Bruxism: A Physiologic Interpretation for Clinical Dentistry 67 Takafumi Kato Introduction 67 Basic Knowledge of Orofacial Sensorimotor Systems 68 Which Event Comes First: Tooth Contact or Jaw Muscle Activity? 72 Sensory Stimuli and Sleep Bruxism 76 Can the Peripheral Sensory System Explain the Role of an Oral Splint in SB Management? 79 Conclusion 81 References 81 Chapter 6 – Emotional Factors in the Etiology of Bruxism 87 Daniele Manfredini Introduction 87 Literature Search 88 Bruxism and Stress 89 Psychosocial Aspects of Bruxism 91 The Relationship between Bruxism and Pain 91 Sleep versus Awake Bruxism, and Grinding versus Clenching Conclusion 95 References 95 Chapter 7 – Movement Disorders in the Dental Office Frank Lobbezoo, Hans L. Hamburger, and Machiel Naeije Introduction 99 Literature Search 100 Dyskinesias 100 Conclusion 105 References 106





Chapter 8 – Bruxism in Children 111 Claudia Restrepo Introduction 111 Etiology of Bruxism in Children 111 Epidemiology of Bruxism in Children 113 Factors Associated with Bruxism 113 Diagnosis of Bruxism in Children 115 Effect of Bruxism on the Dentition of Children 115 Effect of Bruxism on Craniofacial Morphology 117 Bruxism in Children with Special Characteristics 117 Management of Bruxism in Children 118 References 118

PART 2: EFFECTS ON THE MASTICATORY SYSTEM Chapter 9 – Tooth Wear 123 Daniel A. Paesani Introduction 123 Etiology of Tooth Wear 124 Types of Attrition 125 Physiologic Attrition 125 Tooth Wear Quantification 126 Factors Involved in Tooth Wear 129 Tooth Wear Patterns 132 Interpretation of Tooth Wear 138 Conclusion 145 References 147 Chapter 10 – Dental Erosion 149 Daniel A. Paesani Introduction 149 Prevalence 149 Clinical Features and Diagnosis of Erosion 150 Classification of Erosion according to Its Magnitude 155 Classification of Erosion according to Etiology 155 Etiopathogenic Mechanism and Conditioning Factors 169 Salivary Secretion and Buffering Capacity Quantification 176 References 183



Chapter 11 – Gastroesophageal Reflux as a Cause of Dental Erosion Sergio Fuster and Carlos Gianoni Introduction 187 Anatomophysiology of the Upper Digestive Tract 187 Definition of Reflux 190 Pathophysiology of Reflux 191 Clinical Manifestations of Reflux 192 Diagnosis of Reflux 196 Role of Dental Practitioners in Diagnosing Reflux 200 Treatment of Reflux 200 Conclusion 202 References 202 Chapter 12 – Controversies on the Effects of Bruxism Daniel A. Paesani Introduction 207 Effects on Dentition 207 Effects on Soft Tissues 220 Effects on Bone 222 References 229



Chapter 13 – Effects of Bruxism on Teeth and Its Relationship with Endodontics Fernando Goldberg Introduction 233 Pulp and Peri-radicular Alterations 233 Alterations in Crown and Root Structural Integrity 243 References 254 Chapter 14 – Influence of Trauma from Occlusion on the Periodontium Guillermo Schinini and Andres R. Sanchez Introduction 257 Periodontal Lesions 258 Occlusal Trauma Lesions 258 Effect of Occlusal Trauma on the Healthy Periodontium 259 Effect of Occlusal Trauma on the Diseased Periodontium 262 Human Clinical Evidence 264 Conclusion 267 References 268





Chapter 15 – Effects of Bruxism on Muscles 271 Arturo E. Manns Freese Introduction 271 Principles of Skeletal Muscle Physiology 272 Ultrastructure of Skeletal Muscle 275 Comparing Normal Function and Parafunction 280 Pathophysiology of Muscular Disorders and Related Pain Types of Muscular Pain 283 Conclusion 293 References 294


Chapter 16 – Temporomandibular Joint Dysfunction and Bruxism Xiomara Restrepo-Jaramillo, Ross H. Tallents, and Stephanos Kyrkanides Introduction 297 Definitions 297 Prevalence Studies 298 Etiology 299 Pathways to Joint Degeneration 300 The Role of Bruxism 301 Conclusion 304 References 304


Chapter 17 – Pain and Bruxism 309 Peter Svensson, Faramarz Jadidi, Taro Arima, and Lene Baad-Hansen Introduction 309 Overview of Pain Mechanisms 309 Sex-related Differences in Pain Experience 313 Pain Genetics 314 Experimental Bruxism and Craniofacial Pain 314 Clinical Studies of Bruxism and Craniofacial Pain 317 Intervention Studies of Bruxism 320 Conclusion 321 References 322

PART 3: CLINICAL APPROACHES Chapter 18 – Pharmacologic Considerations in Bruxism Marcelo Kreiner Introduction 327




Anxiolytic Drugs 328 Antidepressant Drugs 329 Neuroleptics 331 Addictive Social Drugs 332 Adrenergic Antagonists and Agonists Agonists of Dopaminergic Receptors Antiepileptics 335 References 336

334 334

Chapter 19 – Dental Materials for the Bruxing Patient Marta M. Barreiro and Ricardo L. Macchi Introduction 339 Criteria for Material Selection 340 General Wear Processes 343 Evaluation of Wear Behavior 348 Degradation of Restorative Materials 350 Conclusion 355 References 355


Chapter 20 – Evidence Related to the Treatment of Bruxism Daniel A. Paesani Introduction 359 Treatments for Sleep Bruxism 359 Awake Bruxism 374 References 378 Chapter 21 – Introduction to Complex Oral Restoration Daniel A. Paesani and Fernando Cifuentes Introduction 383 Centric Relation 383 Axis of Rotation of the Mandible 394 The Anterior bite Plane Method 398 References 412



Chapter 22 – Restoration of the Worn Dentition 415 Anders Johansson, Ann-Katrin Johansson, Ridwaan Omar, and Gunnar E. Carlsson Introduction 415 Historical Aspects 415 Epidemiology 416 XVIII


Etiology of Tooth Wear 418 Principles and Management Strategies for Tooth Wear Rehabilitative Strategies 423 Maintenance Phase 436 Conclusion 436 References 437


Chapter 23 – Effects of Bruxism on Restorative Implant-assisted Prosthesis Treatments Jorge Mario Galante Introduction 439 Peri-implant Pathology Classification 441 Classification of Complications of IAP Restorative Treatments 449 Prosthetic Rehabilitation with Implants in Bruxers 454 Conclusion 464 References 464


Chapter 24 – Botulinum Toxin in the Treatment of Bruxism 467 Daniele Manfredini and Luca Guarda Nardini Introduction 467 History of Botulinum Toxin as a Therapeutic Drug 467 Mechanism of Action 468 Fields of Application 469 Safety of Botulinum Toxin Treatments 469 Orofacial Pain Relief 470 Temporomandibular Disorders 470 Botox and Bruxism 471 Conclusion 473 References 473 Chapter 25 – Clinical Treatment of Bruxism 477 Daniel A. Paesani and Fernando Cifuentes Canine Guidance in the Control of Bruxism Effects Bruxism Splints 484 Fabrication of the Bruxism Splint 490 Bruxism Splint Maintenance 515 Treatments with Botulinum Toxin 516 References 522 Index


525 XIX

Part 1 Overview of the problem

Chapter 1

Introduction to Bruxism Daniel A. Paesani

Introduction In the glossary of terms of the American Academy of Orofacial Pain, bruxism is defined as a “total parafunctional daily or nightly activity that includes grinding, gnashing, or clenching of the teeth. It takes place in the absence of subjective consciousness and it can be diagnosed by the presence of tooth wear facets which have not resulted from the chewing function”.1 In order to understand the remoteness of the act of “gnashing the teeth”, we can cite the following passages from the Bible: Psalm 35:16 “Like profane mockers at a feast, they gnash at me with their teeth” Psalm 112:10 “The sinner shall see and be angry, he shall gnash his teeth and consume away” Job 16:9 “he grinds his teeth at me” Matthew 8:12 “But the children of the kingdom shall be cast out into outer darkness: there shall be weeping and gnashing of teeth” At the beginning of the twentieth century, Karolyi used the term “traumatic neuralgia” to

refer to the grinding of the teeth and described it as the cause of a periodontal condition by then called pyorrhea.2 The term “bruxism” comes from the Greek expression brychein odontas that means grinding the teeth. In French, bruxomanie was used for the first time by Marie and Pietkiewicz in 1907.3 Then, Frohman was responsible for the first publication in the odontological literature when he referred to “bruxomania” as a pure psychological state.4

The Importance of Bruxism in Daily Care Bruxism may be considered a normal habit; but under certain circumstances, such as an increase in the frequency of episodes and the strength of masseter contractions, it may turn into a phenomenon with pathological consequences.5 Bruxism may dramatically change the result and the duration of the delicate and careful treatments performed by clinicians. Whereas a soft form of bruxism hardly ever affects oral structures, a hard manifestation 3

Daniel A. Paesani

Table 2-1 Questionnaire for detection of bruxism. Yes


Don’t know

Do you grind your teeth when you sleep? Has anybody heard you grind your teeth while you sleep? On waking up, do you usually find that you are clenching your teeth? When you wake up, do you usually have jaw pain or jaw fatigue? When you wake up, do you usually have the feeling that your teeth are loose? When you wake up, do you usually have sore teeth and/or sore gums? When you wake up, do you usually have a headache in the temples? When you wake up, do you usually have a jaw lock? Have you ever found that you were clenching your teeth in the daytime? Have you ever found that you were grinding your teeth in the daytime?

• complementary methods: use of intraoral devices for tooth wear quantification (splints; Bruxcore®, Boston, MA, USA) and bite force detectors; masseter electromyography (EMG, ambulatory EMG, disposable EMG devices such as BiteStrip®); and sleep polysomnography.

Fig 2-1 Enamel fracture in both central incisors, as a result of bruxism in the protrusive direction. Note also the abrasive wear of vestibular enamel, caused by hard tooth brushing.


Clinical Diagnosis Symptoms A rapid way of collecting information is to request the patient to answer a questionnaire. It is the most widely available method to be used in everyday practice. Chapter 1 has already discussed the advantages and disadvantages of this method in the diagnosis of bruxism symptoms. Questionnaires are very useful for obtaining a great amount of information in a short time. A good questionnaire should include a wide range of questions concerning the patient’s general health status, diseases, medication, etc. Of course, as the main subject of this book is bruxism, we will just be dealing with the questions that specifically refer to it. Table 2-1 shows sample questions that can be added to the general questionnaire usually used during the patient’s first appointment; such a general questionnaire is simply about a collection of symptoms that can be attributed to bruxism. It is advisable to include “Don’t know” among the

Diagnosis of Bruxism



possible choices; this will prevent false-positive and false-negative answers from patients who are not sure of how to respond. At the first appointment, during history taking, it is recommended that the clinician quickly asks the patient the same questions from the questionnaire again in order to confirm the accuracy of the patient’s answers.

Signs In the clinical examination, some signs may be present to suggest bruxism. The character of these signs (and symptoms) is “relative”, since they alone are not sufficient evidence of bruxism; although frequently mentioned in the literature, the fact is that they have not yet been validated by scientific method. Future controlled investigations will have to determine the corresponding sensitivity and specificity values for each of them. So far, only the clinical validity of tooth-grinding sounds during


Fig 2-2 (a) Fracture line in a mandibular molar (arrow) caused by bruxism of the clenching type. (b) No fracture is evident in the periapical radiograph, although a reactive area in the interradicular space can be seen (arrow). (c) Opening of the molar reveals that the fracture has reached the pulp chamber (arrow).

sleep (witness statements based on two episodes per week) has been studied. When checked against polysomnography, they showed a sensitivity of 78% and a specificity of 98%.1 Tooth wear Although this has a strong association with bruxism, it is not a specific sign since there are many causes of tooth wear. Grinding causes the teeth to deteriorate in a specific way (attrition). Tooth wear can be studied by direct visual inspection of the mouth, by examining plaster models of the patient’s teeth, and by taking a look at intraoral pictures. This subject is discussed in detail in Chapter 9. Fractures There may be fractures in natural teeth, prostheses, dental implants, and dental restorations (Figs 2-1 to 2-11). 23

Marta M. Barreiro and Ricardo L. Macchi



Fig 19-10 Proximal contact between restorations with different hardnesses: (a) porcelain–metal, and (b) porcelain–composite. Several mechanisms are present – two-body, three-body, and corrosive wear.


In the case of bruxism, two-body wear or attrition is found. Tooth surfaces come into direct contact, the frequency of sliding is incremented as well as the loads that are applied, and all these factors lead to significantly greater wear and increased possibility of fatigue failure.15

Evaluation of Wear Behavior Laboratory simulator and clinical studies can be used to evaluate intraoral wear. b Fig 19-11 (a and b) Proximal wear in teeth with proximal composite resin restorations. This type of wear is also seen on enamel and is increased in the presence of periodontal mobility. (Modified from Söderholm.28)

lubricant that acts in each case can be seen in Table 19-3. The contacts can be tooth against tooth, tooth against restoration, restoration against restoration, as well as a tooth brush or other foreign body – which includes foods. Corrosive wear or erosion can take place when a chemical process is added, as happens by the effect of acid in bulimic patients. Wear by superficial fatigue can be the consequence of a habit such as biting on a solid object (e.g., a pen), which involves the application of high compressive loads. 348

In-vitro Laboratory Studies The use of in-vitro studies provides an approximation of the evaluation of wear of new materials before their clinical application.31,32 Is the prediction of wear behavior of dental materials possible? One important point to keep in mind when evaluating lab studies is the difficulties that appear when attempting to simulate conditions present in the oral cavity. The very many variables that participate in wear make its measurement with a single parameter difficult, even when variations seen from patient to patient are not considered.31 The weak correlation that is seen between mechanical properties and wear is remarkable. Some physical properties such as water sorption can give just a hint of potential wear, particularly when corrosive wear is considered.

Dental Materials for the Bruxing Patient

Table 19-3 Most frequent wear types within the oral cavity: comparison between dental and materials science terminology (modified from Vale Antunes and Ramalho3). Causes of wear

Dental term

Material terminology


Physiologic Without occlusal contact Direct contact Contact and sliding

Abrasion Attrition Attrition

Three-body Two-body Two-body

Saliva/food Saliva Saliva

Pathologic Bruxism Xerostomia Chemical attack Negative habits

Attrition Attrition Erosion Attrition/abrasion

Two-body Two-body Corrosion Two- or three-body

Saliva – Saliva –

Hygiene Tooth brushing




Clinical Studies Understanding clinical wear requires studies in which the different factors that interact are taken into account. Clinical studies are the best option in the actual evaluation of wear, but they are expensive and need to be long term.33–35 Clinical wear can be expressed by the amount (in micrometers) of material loss per year, using normal tooth wear for comparison. For example, the American Dental Association considers that a loss no greater than 50 μm per year has to be established by means of systematic clinical studies if a material is to be used in posterior restorations. Both direct and indirect methods are used in these studies. Most of the direct studies follow criteria that have been established by Ryge:36 color matching, marginal integrity, secondary caries, anatomic form, and surface roughness. Some changes in categorization are introduced according to each study’s specific needs. Inter-examiner variability is the main limitation to obtaining adequate discrimination in the use of scales.

Indirect methods use impressions and models, which are evaluated, or epoxy resin replicas that can reproduce worn surfaces, and scanning electron microscopy observation. Loss of vertical dimension is commonly measured in clinical studies. Visual examination is fast and no additional cost is required, but it is prone to subjective variation; often just changes in anatomic force are registered without any quantification. Special optical or scanning electron microscopes and profilometers allow for greater precision in the evaluation of material loss. Surface changes in exposed cavity walls can be evaluated so as to establish the types of wear that are present. Many discrepancies are seen between results from in-vitro lab studies and observation in longterm clinical studies. The evaluation of actual behavior with reliable measurements is still a problem to be solved. Present efforts are focused on the use of wear simulators for wear studies, and these results have be corroborated later by clinical studies.31 349

Daniel A. Paesani and Fernando Cifuentes



c Fig 25-32 Occlusal adjustment of the splint. (a) Ask the patient to close their mouth repeatedly and give a series of taps with their teeth on the splint, while articulating paper is placed between the splint and the teeth. (b and c) The aim is to obtain one contact point per cusp or antagonist incisal edge.


Splint attachment problems are much simpler to solve, since only retainer tightening is required. In order to perform splint occlusal adjustment, it is advisable not to polish the surface of the splint fully. Another option is to request the laboratory to deliver the splint with a coarse surface, or to remove the splint’s gloss by using thin sandpaper in order to better visualize occlusal contacts. Once the patient is in the dorsal recumbent position, they are requested to give a series of quick taps with their teeth on the splint, while articulating paper is made to come between splint and teeth (Fig 25-32). An acrylic bur is used to wear out all the premature contact points. This procedure is repeated as many times as necessary, until all the vestibular cusps and incisal edges simultaneously occlude on the surface of the splint. The simultaneous contacts obtained during mouth closure are comparable to maximum intercuspation at a dental level. Thus, each of these points (closure stops) will be responsible for the stability of its respective antagonist tooth. Also, the combined action of all of them guarantees a steady position of the jaw during mouth closure and, especially, during tooth clenching episodes while the bruxer is wearing the splint. Next, the aim is to make anterior guidance harmonious (Figs 25-33 and 25-34). To do this, it is advisable to use articulating paper of a different color. Articulating paper is placed between the teeth and the splint while having the patient make lateral and protrusive movements. Any contact in the posterior segment should be carefully removed, with the exception of those contacts matching the ones obtained in the previous step (closure stops). In short, during closure, one contact per cusp or lower incisal edge should occur in the splint; during eccentric movements (lateral movement and protrusion), the anterior guidance should prevent premolar and molar cusps from coming into contact with the surface of the splint.

Clinical Treatment of Bruxism



Fig 25-33 (a) With articulating paper of a different color, anterior guidance functioning is tested. (b) The white arrows indicate the trajectories created during lateral movements; the black arrows indicate protrusive movement trajectories.


Fig 25-34 (a–c) Correct functioning of the anterior guidance of the splint causes the posterior segments to separate and protects them against premature wear during tooth grinding episodes.