Textbook of Endodontology E-Book

• Herausgeber: John Wiley & Sons
• Kategorie: Fachliteratur
• Sprache: Englisch

Seitenzahl: 1096

Veröffentlichungsjahr: 2013

Beschreibung

The second edition of Textbook of Endodontology continues the aim of serving the educational needs of dental students and dental practitioners searching for updates on endodontic theories and techniques.

Significantly restructured and completely updated, the new edition maintains the ethos of the original, facilitating ease of learning through pedagogical features such as annotated references, core concepts and key literature. It features a number of new chapters on topics ranging from outcomes of endodontic treatment to managing endodontic complications to dental trauma.  Additionally, all other chapters have been thoroughly revised and brought up to date to reflect contemporary knowledge and practice.

Textbook of Endodontology continues its important function of providing lucid scholarship and clear discussion of biological concepts and treatment principles in endodontics, and as such will be an important update to its current readers and a valuable discovery to its new audience.

Leseprobe

Contents

List of Contributors

Preface

Chapter 1   Introduction to endodontology

Endodontology

The dawn of modern endodontology

The objective of endodontic treatment

Clinical problems and solutions

The diagnostic dilemma

The tools of treatment

Extraction and dental implant?

References

Part 1   The Vital Pulp

Chapter 2   The dentin–pulp complex: structures, functions and responses to adverse influences

Introduction

Constituents and normal functions of the dentin–pulp complex

Basal maintenance

Appropriate responses of the healthy pulp to non-destructive stimuli

Responses to external threats

Effects of potentially destructive stimuli

References

Chapter 3   Dentinal and pulpal pain

Introduction

Classification of nerve fibers

Morphology of intradental sensory innervation

Function of intradental sensory nerves under normal conditions

Sensitivity of dentin: hydrodynamic mechanism in pulpal A-fiber activation

Responses of intradental nerves to tissue injury and inflammation

Local control of pulpal nociceptor activation

Dentin hypersensitivity

Pain symptoms and pulpal diagnosis

References

Chapter 4   Treatment of vital pulp conditions

Introduction

Clinical scenarios

Treatment options

Factors influencing choice of treatment

Management of exposed pulps by direct pulp capping/partial pulpotomy

Pulpectomy

Emergency treatment

References

Chapter 5   Endodontics in primary teeth

Introduction

The normal pulp

Pulpal inflammation in the primary tooth

Wound dressings – characteristics, modes of action and reported clinical success rates

Objectives of pulp treatment

Operative treatment procedures

Indications and contraindications for pulp treatment in primary teeth

Future directions

References

Part 2   The Necrotic Pulp

Chapter 6   The microbiology of the necrotic pulp

Introduction

Evidence for the essential role of microorganisms in apical periodontitis

Routes of microbial entry to the pulpal space

Modes of colonization

Ecological determinants for microbial growth in root canals

Methods for studying the root canal microflora

Composition of the endodontic microflora

Association of signs and symptoms with specific bacteria

Concluding remarks

References

Chapter 7   Apical periodontitis

Introduction

The nature of apical periodontitis

Interactions with the infecting microbiota

Clinical manifestations and diagnostic terminology

References

Chapter 8   Systemic complications of endodontic infections

Introduction

Acute periapical infections as the origin of metastatic infections

Chronic periapical infections as the origin of metastatic infections

References

Chapter 9   Treatment of the necrotic pulp

Introduction

Objectives and general treatment strategies

Scheme for a routine procedure in root canal therapy

Considerations in complex cases

Effects of root canal therapy on the intracanal microbiota

Management of symptomatic lesions

References

Part 3   Endodontic Treatment Procedures

Chapter 10   The surgical microcope

Introduction

Components

Ergonomics and working techniques

Microinstrumentation

Critical steps

Concluding remarks

References

Chapter 11   Root canal instrumentation

Introduction

Principles of root canal instrumentation

Root canal system anatomy

Procedural steps

Endodontic instruments

Instrumentation techniques

Limitations of root canal instrumentation

Preventing procedural mishaps

References

Chapter 12   Root canal filling materials

Introduction

Requirements

Gutta-percha cones

Sealers

Materials for retrograde fillings (root-end fillings) and replantation

Mandibular nerve injuries

References

Chapter 13   Root filling techniques

Introduction

Specific objectives

Selecting a root canal filling material

Root filling techniques for gutta-percha

Root filling techniques employing gutta-percha and sealer

Procedures prior to root canal filling

Assessing root filling quality

Filling of the pulp chamber and coronal restoration

Conclusions and recommendations

References

Part 4   Diagnostic Considerations and Clinical Decision Making

Chapter 14   Diagnosis of pulpal and periapical disease

Introduction

Evaluation of diagnostic information

Diagnostic strategy

Clinical manifestations of pulpal and periapical inflammation

Collecting diagnostic information

Diagnostic classification

References

Chapter 15   Diagnosis and management of endodontic complications after trauma

Introduction

Common dental injuries

Dental trauma and its consequences

General considerations in the management of dental trauma

Diagnostic quandaries – to remove or review the pulp after trauma?

Pulp regeneration – the dawn of a new era?

References

Chapter 16   The multidimensional nature of pain

Introduction

Neurobiological factors affecting the pain experience

Psychological factors affecting the pain experience

Gender and pain

Special populations

Management and treatment of pain

Concluding remarks

References

Chapter 17   Clinical epidemiology

Introduction

Clinical epidemiology

Diagnosis

Cause

Prevalence, frequency and incidence

Risk for apical periodontitis

Treatment

Prognosis

Longevity of root filled teeth

Back to the case

References

Chapter 18   Endodontic decision making

The outcome of endodontic treatment

Factors influencing treatment outcome

Prevalence of endodontic “failures”

Variation in the management of periapical lesions in endodontically treated teeth

Clinical decision making: descriptive projects

Endodontic retreatment decision making: a normative approach

Concluding remarks

References

Part 5   The Root Filled Tooth

Chapter 19   The root filled tooth in prosthodontic reconstruction

Introduction

Problems associated with root filled teeth as abutments

Core build-ups

Clinical techniques

Prosthodontic reconstruction

References

Chapter 20   Non-surgical retreatment

Introduction

Indications

Access to the root canal

Access to the apical area

Instrumentation of the root canal

Antimicrobial treatment

Preventive retreatment

Prognosis

References

Chapter 21   Surgical endodontics

Introduction

General outline of the procedure

Pain control after surgery

Bone healing

Prognosis

References

Failures after surgical endodontics

Index

This edition first published 2010

© 2003 Blackwell Munksgaard

© 2010 Blackwell Publishing Ltd

Blackwell Publishing was acquired by John Wiley & Sons in February 2007. Blackwell’s publishing programme has been merged with Wiley’s global Scientific, Technical, and Medical business to form Wiley-Blackwell.

First edition published 2003

Second edition 2010

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Library of Congress Cataloging-in-Publication Data

Textbook of endodontology/edited by Gunnar Bergenholtz, Preben Hørsted-Bindslev, Claes Reit. — 2nd ed.

p. ; cm.

Includes bibliographical references and index.

ISBN 978-1-4051-7095-6 (hardback: alk. paper) 1. Endodontics. I. Bergenholtz, Gunnar.

II. Hørsted-Bindslev, Preben. III. Reit, Claes.

[DNLM: 1. Dental Pulp Diseases—therapy. 2. Periapical Diseases—therapy. WU 230 T355 2010]

RK351.T49 2003

617.6'342—dc22

2009024733

A catalogue record for this book is available from the British Library.

Set in 9.5/12.5pt Palatino by Gray Publishing, Tunbridge Wells, Kent

Illustrations by Jens Lund Kirkegaard

1 2010

List of Contributors

Editors

Gunnar Bergenholtz

Institute of Odontology, The Sahlgrenska Academy at University of Gothenburg, Sweden

Preben Hørsted-Bindslev

School of Dentistry, Faculty of Health Sciences, Aarhus University, Denmark

Claes Reit

Institute of Odontology, The Sahlgrenska Academy at University of Gothenburg, Sweden

Contributors

Itzhak Abramovitz

Hebrew University and Hadassa Faculty of Dental Medicine, Hebrew University, Jerusalem, Israel

Thomas von Arx

School of Dental Medicine, University of Berne, Switzerland

Vidar Bakken

Faculty of Medicine and Dentistry, University of Bergen, Norway

Lars Bergmans

School of Dentistry, University of Leuven, Belgium

Luis Chávez de Paz

Faculty of Odontology, Malmö University, Sweden

Ilana Eli

The Maurice and Gabriela Goldschleger School of Dental Medicine, Tel Aviv University, Israel

Lise-Lotte Kirkevang

School of Dentistry, Faculty of Health Sciences, Aarhus University, Denmark

Eckehard Kostka

School of Dental Medicine, Charité, Medical Faculty of the Berlin Humboldt University, Germany

Paul Lambrechts

School of Dentistry, University of Leuven, Belgium

Pierre Machtou

Denis Diderot School of Dentistry, Paris 7 University, France

Ingegerd Mejàre

Faculty of Odontology, Malmö University, Sweden

Zvi Metzger

The Maurice and Gabriela Goldschleger School of Dental Medicine, Tel Aviv University, Israel

Matti Närhi

Faculty of Medicine, University of Kuopio, Finland

Leif Olgart

Karolinska Institute, Stockholm, Sweden

Kerstin Petersson

Faculty of Odontology, Malmö University, Sweden

Gottfried Schmalz

School of Dentistry, University of Regensburg, Germany

Nils Skaug

deceased

Gunnel Svensäter

Faculty of Odontology, Malmö University, Sweden

Peter Svensson

School of Dentistry, Faculty of Health Sciences, Aarhus University, Denmark

Else Theilade

School of Dentistry, Faculty of Health Sciences, Aarhus University, Denmark

Peter Velvart

Private practice, Zürich, Switzerland

Paul Wesselink

Academic Center for Dentistry Amsterdam (ACTA), The Netherlands

John Whitworth

School of Dental Science, Newcastle University, UK

Preface

The Textbook of Endodontology is intended to serve the educational needs of dental students, as well as of dental practitioners seeking updates on endodontic theories and techniques. The primary aim has been to provide an understanding of the biological processes involved in pulpal and periapical pathologies and how that knowledge impinges on clinical management, and to present that information in an easily accessible form. Therefore, we have supplemented the core text with numerous figures and photographs, as well as with boxes highlighting key facts, important clinical procedures and key research. Case studies are given at the end of some chapters in order to further illustrate topics described in the text. In these various ways, the book provides information both at a foundation level, and at a more detailed level for the graduating student and practitioner.

The key information boxes are color coded as an easy-to-use navigational aid for readers. Core concepts are colored pink, while advanced concepts are purple. Clinical procedures are coded green and key literature boxes are blue.

Although not designed to provide a comprehensive review of the literature, this book is also intended to stimulate the reader to delve into the research that forms our current knowledge base in endo dontology. To aid the reader, a selective reference list is provided and comments have been added to especially weighty or useful references. Important and interesting investigations are presented in the core and advanced concept boxes, and we hope that these features will encourage the student to carry on with his or her own exploration of the subject area.

This is the second edition of the book, which features three new chapters reflecting the use of the surgical microscope, diagnosis and management of endodontic complications subsequent to dental trauma, and endodontic epidemiology. The dedicated support of our coauthors – 23 highly respected clinicians and scientists – who, in addition to the editors, have contributed to this book, is greatly appreciated. We thank them all sincerely for their time, effort and endurance during the editing process.

Gunnar BergenholtzPreben Hørsted-BindslevClaes Reit

Chapter 1

Introduction to endodontology

Claes Reit, Gunnar Bergenholtz and Preben Hørsted-Bindslev

Endodontology

The word “endodontology” is derived from the Greek language and can be translated as “the knowledge of what is inside the tooth”. Thus, endodontology concerns structures and processes within the pulp chamber. But what about “knowledge”? What does it actually mean to “know” things? Most people would probably say that knowledge has something to do with truth and providing reasons for things. It is often believed that dental and medical knowledge is simply scientific knowledge – science is based on research and deals with how things are constructed and work. But as practicing dentists we also need other types of knowledge. Although it is important to know about tooth anatomy and how to produce good root canal preparations for example, we must also develop good judgment and ability to make the “right” clinical decisions. There are at least three different forms of knowledge that the dental practitioner requires and, in a tradition that goes all the way back to Aristotle, we will refer to the Greek terms for these forms: episteme, techne and phronesis (1).

Episteme

Episteme is the word for theoretical–scientific knowledge. The opposite is doxa, which refers to “belief” or “opinion”. There is a massive body of epistemic knowledge within endodontology, for example on the biology of the pulp, the microorganisms that inhabit root canals, the procedures and materials used in the clinical practice of endodontology (endodontics) and the outcome of endodontic therapies. Science produces “facts”. It must be understood that modern science is an industry and is affected by many factors, both internal and external. Although this is not the place to discuss the philosophy of science, the concept of “truth” and the growth of scientific knowledge is not unproblematic. There has been substantial contemporary philosophical discussion reflecting on epistemic knowledge, and the interested reader is referred to one of the many good introductory texts that are available (3).

The results of science are presented in lectures, articles and textbooks. So from a student’s point of view the learning situation is rather straightforward, provided that the subject is structured well and ample time given for reading and reflection. This book, in large part, is composed of epistemic knowledge.

Techne

The first person to challenge the deeply intrenched theoretical concept of knowledge was the British philosopher Gilbert Ryle. In his book The Concept of Mind (10) he introduces “knowing-how” and distinguishes it from “knowing-that”. “Knowing-how” is practical in nature and concerns skills and the performance of certain actions. This concept of knowledge implies the ability not only to do things, but also to understand what you are doing. To say that you have practical knowledge, it is not enough to produce things out of mere routine or habit. You have to “know” what you are doing and be able to argue about it. Practice must be combined with reflection. The idea that there is a tacit or silent dimension of knowledge has had a great impact on the contemporary discussion. Michael Polanyi, for example, said that “We know more than we can tell” (9). When trying to explain how we master practical things such as riding a bicycle or recognizing a face, it is not possible to articulate verbally all the knowledge that we have. Certain important aspects are “tacit”. Likewise, it is not sufficient to teach students about root canal preparation simply by asking them to read a book or presenting the subject matter in a lecture. It has to be demonstrated. Knowledge is very often transmitted by the act of doing.

A substantial body of endodontic knowledge must be characterized as techne. It is not possible to learn all about the procedures in endodontology by studying a textbook. Observing a good clinical instructor, watching other dentists at work, performing the procedures oneself and reflecting on what has been learned are all important.

Phronesis

According to Aristotle, phronesis is the ability to think about practical matters. This can be translated as “practical wisdom” (5) and is concerned with why we might decide to act in one way rather than in another. When thinking about the “right” action or making the “right” decision we enter the territory of moral philosophy. The person who has practical wisdom has good moral judgment. Modern ethical thinking has been influenced significantly by ideas that originated during the enlightenment. Morality is concerned with human actions and there are certain principles that can separate “right” from “wrong” decisions. Jeremy Bentham (2) and the utilitarians launched the utility principle and Immanuel Kant (6) invented the categorical imperative, each creating a tradition with great impact on today’s medical ethics and decision making.

Aristotle, on the other hand, believed that there are no explicit principles to guide us. He understood practical wisdom as a combination of understanding and experience and the ability to read individual situations correctly. He thought that phronesis could be learnt from one’s own experience and by imitating others who had already mastered the task. He stressed the cultivation of certain character traits and the habit of acting wisely.

The clinical situation demands that the dentist exercises practical wisdom, “to do the right thing at the right moment”. In order to develop phronesis, theoretical studies of moral theory and decision-making principles might be helpful. Neoaristotelians such as Martha Nussbaum (8) have suggested that reading literature should be part of any academic curriculum, the idea being that it increases our knowledge and understanding of other people. However, the essence of phronesis has to be learnt from practice.

Concepts of endodontology

From the above it can be concluded that endodontology encompasses not only theoretical thinking but also the practical skills of a craftsperson and the practical thinking needed for clinical and moral judgment. Unfortunately, through the years, undue prestige has been given to theoretical–scientific thinking and this has hindered the development of a rational discussion of the other types of knowledge. The serious student of endodontology has to investigate all three aspects, but, as argued above, there are limits to what can be communicated within the covers of a textbook.

The dawn of modern endodontology

It all started with a speech at the McGill University in Montreal. In the morning of October 3, 1910, Dr William Hunter gave a talk entitled “The role of sepsis and antisepsis in medicine”. Hunter said that:

“In my clinical experience septic infection is without exception the most prevalent infection operating in medicine, and a most important and prevalent cause and complication of many medical diseases. Its ill-effects are widespread and extend to all systems of the body. The relation between these effects and the sepsis that causes them is constantly overlooked, because the existence of the sepsis is itself overlooked. For the chief seat of that sepsis is the mouth; and the sepsis itself, when noted, is erroneously regarded as the result of various conditions of ill-health with which it is associated – not, as it really is, an important cause or complication.

“Gold fillings, gold caps, gold bridges, gold crowns, fixed dentures, built in, on, and around diseased teeth, form a veritable mausoleum of gold over a mass of sepsis to which there is no parallel in the whole realm of medicine or surgery. The whole constitutes a perfect gold trap of sepsis.”

The cited text was published in the Lancet in 1911. But Hunter’s words rapidly spread and were intensively discussed among laymen and given banner headlines in the newspapers. Essentially, Hunter proposed that microorganisms from a dental focus of infection can spread to other body compartments and cause serious systemic disease. The fear that illnesses and even those of chronic or of unknown origin were caused by oral infections, brought thousands of people to the waiting rooms of dentists with demands to have their teeth removed. As a result of the focal infection theory teeth were extracted in enormous numbers.

Although not directly stated by Hunter, teeth with necrotic pulps were seen as one of the main causes of “focal infection”. Laboratory studies had disclosed the presence of bacteria in the dead pulp tissue. In the 1920s, dental radiography came into general use and radio-lucent patches around the apices of teeth with necrotic pulps indicating an inflammatory bone lesion were possible to detect. If such teeth were extracted and cultured, microorganisms were often recovered from the attached soft tissue. It became virtually incontestable that pulpally diseased teeth should be removed.

Reflecting on this period in the history of dentistry, Grossman (4) wrote: “The focal infection theory promulgated by William Hunter in 1910 gave dentistry in general, and root canal treatment in particular, a black eye from which it didn’t recover for about 30 years.” However, in hindsight, this period can also be regarded as the dawn of modern endodontology. Researchers started to question and oppose the clinical consequences of the focal infection theory. Microbiologists began mapping out the microflora of infected root canals. Pathologists investigated the reaction patterns of the pulp and peri-apical tissues and came to understand the protective power of the host defense mechanisms. Clinicians invented aseptic methods to treat the root canal, and radiography made it possible to confine the procedures to within the root canal space. It was further demonstrated that root canal infections could be combated successfully and it became obvious that root canal infections were not such a serious threat to the human organism as once believed. Pulpally compromised teeth could therefore be spared and endodontic treatment became a necessary skill of the modern dentist.

The objective of endodontic treatment

The consequences of inflammatory lesions in the pulp and periapical tissue (Fig. 1.1) have tormented humankind for thousands of years. Historically, therefore, the main task of endodontic treatment has been to cure toothache due to inflammatory lesions in the pulp (pulpitis) and the periapical tissue (apical periodontitis). For a long period of time a commonly used method to remedy painful pulps was to cauterize the tissue with a red-hot wire or with chemicals such as acid. In 1836, arsenic was introduced to devitalize the pulp, a method that would be used for well over 100 years. Procedures to remove the pulp without toxic chemicals were introduced in the early part of the 19th century and small, hooked instruments were used. The advent of local anesthesia at the beginning of the 20th century made pulpec-tomy a painless procedure.

Signs of root canal infection, such as abscesses with fistulae, were also dealt with historically using highly toxic chemicals. These substances were introduced to the root canal, and forced through the foramen into the fistula. Often the treatment was more damaging than the disease condition itself, and the tooth and parts of the surrounding bone were often lost in the process.

Fig. 1.1 A medieval skull found in Denmark showing teeth with serious attrition. In the first left molar the pulp chamber is exposed and the alveolar bone is resorbed around the root apices, indicating a once-present periapical inflammation due to necrosis of the pulp followed by root canal infection.

While relief of pain is still a primary goal of endodontic treatment, patients also may want to exclude the compromised tooth, as both a general and local health hazard. This means that intra- as well as extraradicular infections should be eradicated and that materials implanted in the root canal should be innocuous and not cause adverse tissue reactions or systemic complications. Using modern endodontic treatment procedures, these treatment objectives can be attained in the large majority of cases.

Clinical problems and solutions

The vital pulp

Under normal, physiological conditions the pulp is well protected from injury and injurious elements in the oral cavity by the outer hard tissue encasement of the tooth and an intact periodontium (Fig. 1.2). When the integrity of these tissue barriers is breached for any reason, microorganisms and the substances they produce may gain access to the pulp and adversely affect its healthy condition. The most common microbial challenge of the pulp derives from caries. Even in its early stages substances from caries-causing bacteria may enter the pulp along the exposed dentinal tubules. Like any connective tissue, the pulp responds to this with inflammation. Inflammation has an important aim to neutralize and eliminate the noxious agents. It also organizes subsequent repair of the damaged tissue. Thus, the pulp may react in a manner that allows it to sustain the irritation and remain in a functional state. Yet, when caries has extended to the vicinity of the pulp, the response may take a destructive course and result in severe pain and death (necrosis) of the tissue.

Fig. 1.2 The scope of endodontology: the vital pulp.

An inflamed or injured pulp may have to be removed and replaced with a root filling – a procedure termed pulpectomy. This measure is undertaken especially in cases when the condition of the pulp is such that an inflammatory breakdown is deemed imminent. A manifest infection may otherwise develop in the root canal system.

A pulpectomy procedure is carried out under local anesthesia and with the use of specially designed root canal instruments. These instruments remove the diseased pulp and prepare the canal system so that it can be filled properly. The purpose of the filling is to prevent microbial growth and multiplication in the pulpal chamber. Thus, pulpectomy is a measure primarily aimed at preventing the development of a manifest root canal infection and painful sequelae.

Pulpectomy may also be carried out any time a pulp is directly exposed to the oral environment. This may occur after clinical excavation of caries or after a traumatic insult or iatrogenic injury. If the exposure is fresh and the pulp judged not to be seriously inflamed it may not have to be removed. If the open wound is treated with a proper dressing and protected from the oral environment by pulp capping, healing and repair of the wound are possible. For common terminologies used to specify the endodontic disease conditions and their treatments, see Core concept 1.1.

The necrotic pulp

As mentioned above, injury to the pulp may lead to necrosis of the tissue (Fig. 1.3). The necrotic pulp is defenseless against microbial invasion and will allow microorganisms indigenous to the oral cavity to reach the pulp chamber, either along an open direct exposure or through uncovered dentinal tubules or cracks in the enamel and dentin. Lateral canals exposed as a result of progressive marginal periodontitis may also serve as pathways for bacteria to reach the pulp. The specific environment in the root canal, characterized by the degrading pulp tissue and lack of oxygen, will favor a microbiota dominated by proteolytic, anaerobic bacteria. These microorganisms may organize themselves in clusters and in microbial communities attached to the root canal walls as well as inside the dentinal tubules of the root. In these positions microorganisms stay protected from host defense mechanisms and can therefore multiply rapidly to large numbers. Microorganisms attempt to invade the periodontal tissues via the apical foramen or any other portal of exit from the root canal, and may do so before the host defense has been effectively organized. Once established, however, organisms will normally be held back but not eliminated from the root canal space. A chronic inflammatory lesion will ensue, normally around the root tip, and remain for as long as no treatment is initiated.

Core concept 1.1 Common terms and expressions used for endodontic disease conditions and treatment procedures

PulpitisInflammation of the dental pulp. Symptomatic and asymptomatic pulpitis, as well as irreversible and reversible pulpitis, are commonly used terms to specify lesions with and without painful symptoms. The terms total and partial pulpitis are also in use.Pulp necrosisPulp death. Pulp chamber is devoid of a functional pulp tissue. Necrosis can be more or less complete, i.e. partial or totaI.Apical periodontitisInflammatory reaction of the tissues surrounding the root apex of a tooth. Symptomatic/asymptomatic apical periodontitis and acute/chronic apical periodontitis, respectively, are applied to indicate lesions with and without overt clinical symptoms such as pain, swelling and tenderness. Dental or apical granuloma is a histological term for an established lesion. Apical, periapical and periradicular are interchangeable terms to state the location of the process at or near the root tip.Pulp cappingTreatment procedure aimed at preserving a dental pulp that has been exposed to the oral environment.Partial pulpotomyTreatment procedure by which the most (often inflamed) superficial portion (1-2 mm) of the coronal pulp is surgically removed with the aim of preserving the remaining tissue.PulpotomyTreatment procedure by which the entire coronal pulp tissue is surgically removed with the aim of preserving the remaining tissue. The term pulpotomy is also used to describe a pain-relieving procedure in an emergency treatment of symptomatic pulpitis.PulpectomyTreatment procedure by which pulp tissue (often inflamed) is surgically removed and replaced with a root filling.Root canal treatment (RCT)Treatment of teeth with necrotic pulps where root canals are often infected.Non-surgical retreatmentTreatment of root filled teeth with clinical and/or radiographic signs of root canal infection, where root fillings are removed, canals disinfected and refilled. May also be carried out to improve the technical quality of previous root fillings.Surgical retreatmentTreatment procedure by which the root apex of a tooth is surgically accessed to manage a root canal infection that has not been successfully treated by RCT. Retrograde endodontics or surgical endodontics are other terms for this procedure.

Fig. 1.3 The scope of endodontology: the necrotic pulp.

The periapical tissue reaction is often visible in a radiograph as a localized radiolucency because the adjacent bone has been resorbed in the course of the inflammatory process. The condition may or may not be associated with pain, tooth tenderness and various degrees of swelling.

Treatment of the necrotic pulp is by root canal treatment (RCT) and is aimed to combat the intracanal infection. The canal is cleaned with files in order to remove microbes as well as their growth substrate. Owing to the complex anatomy of the root, instruments cannot reach all parts of the canal system and therefore antimicrobial substances are added to disinfect the canal. In order to avoid reinfection and to prevent surviving microbes from growing, the canal is then sealed with a root filling.

The root filled tooth

Pulpectomy and RCT do not always lead to a successful clinical outcome. For example, a tooth may continue to be tender or periapical inflammation may persist. Such treatment “failures” are often associated with defective root fillings, which allow organisms from the initial microbiota to survive in the root canal or new bacteria to enter via leakage along the margins of the coronal restoration (Fig. 1.4).

Fig. 1.4 The scope of endodontology: the root filled tooth.

The root canal in such cases may be retreated using either a non-surgical or a surgical approach. In non-surgical retreatment the root filling is removed and the canal is reinstrumented. Antimicrobial substances are applied to kill the microbes and the space is refilled. Crowns, bridges and posts may mean that it is sometimes not feasible to reach the root canal in a conventional way. In such cases, a surgical retreatment may be attempted. A mucoperiosteal flap is then raised and entrance to the apical part of the root made through the bone. Surgical retreatment often involves cutting of the root tip, instrumentation of the apical root portion and placement of a filling at the apical end.

The diagnostic dilemma

The disease processes in the pulp and periapical tissues take place in a concealed body compartment that normally is not available for direct inspection. Instead, the clinician has to rely on indirect information to assess the condition of the tissue and reach a diagnosis. The reliance on indirect signs and symptoms entails the risk of making false-positive and false-negative diagnoses. For example, the patient’s report of pain has been found to be an inaccurate sign because there is no exact relationship between the amount of tissue damage and level of pain encountered. Furthermore most inflammatory episodes within the pulp or periapical bone pass by without symptoms. Another factor is that the discriminatory ability of the intrapulpal nerves is not perfect, which means that if a patient has toothache due to pulpitis there is a high risk that he or she may “point out the wrong tooth”. Nevertheless a patient’s experience of pain and especially its character serve as important indicators of an endodontic disease condition. Along with pulp vitality testing and radiographic examination, the disease history is a prime source of diagnostic data. Yet, to avoid erroneous diagnoses all data have to be interpreted with utmost care and with in-depth knowledge of possible errors and the factors that influence diagnostic accuracy.

The tools of treatment

To many dentists, RCT can best be described by using Winston Churchill’s words on golf: “An impossible game with impossible tools”. The complexity of root canal anatomy, the relative stiffness of root canal instruments, being unable, often, to visualize the area properly, and the lack of space in the mouth provide substantial challenges to the skill and patience of the dentist. Intracanal work is exceptionally demanding; this is clearly demonstrated by numerous radiographically based epidemio-logical surveys, which repeatedly report that many root fillings do not meet acceptable technical standards. Because clinical outcome is strongly related to the quality of treatment, the high frequency of substandard performances is a subject of great concern to the profession.

The last 10–15 years have seen a tremendous technological development that facilitates endodontic treatment and enhances the potential to increase its overall standard (7). For example, the advent of super-flexible nickel–titanium alloy has made it possible to fabricate instruments that are highly flexible and can follow the anatomy of the root canal and therefore produce good quality canal preparations. Furthermore, systems have been developed that allow the instruments to be maneuvered by machine rather than by hand, improving fine-scale manipulation and decreasing operator fatigue.

The surgical microscope has brought light and vision into the pulp chamber. Working under high magnification, it is now far easier to remove mineralizations, locate small root canal orifices and control intracanal procedures than with the naked eye or with loupes. However, high-quality microscopes are expensive and, thus far, the technology has found limited adoption by dentists other than those specialized in endodontics.

In the midst of this technological boom it must not be forgotten that endodontics is primarily about controlling infection. While the intracanal work is aimed to eliminate infectious elements and give space for the subsequent root filling, this effort would be futile if measures were not undertaken to prevent oral contaminants from entering the root canal space during the procedure. Luckily, there are few medical treatments that can be carried out as aseptically as endodontic therapy. Shielding the tooth with a rubber dam is the oldest and still the most effective way to ensure that the operation field remains sterile (Fig. 1.5). This measure also facilitates the procedure and is critically important to the clinical success of endodontic therapy.

Fig. 1.5 Rubber dam isolated tooth, which is in the process of being disinfected.

Extraction and dental implant?

Extraction and placement of dental implants to replace endodontically compromised teeth has gained popularity in recent years. Such a measure can certainly be a valuable option in cases of severely damaged teeth that either have a hopeless prognosis or cannot be provided with a proper restoration. Yet, dental implants must not be overused or misused because an endodontic treatment, for example, may appear complicated. Clearly endodontic therapy represents a very realistic opportunity to restore most teeth with diseased pulps to a healthy state. Indeed endodontic therapy has reached a level of sophistication today that dentists, with proper knowledge and training, can carry out the procedures with a high rate of success. Epidemiological data have furthermore shown that endodontically treated teeth maintain a functional place in the oral cavity for long periods of time (11).

References

1. Aristotle (Iruin T, ed.). Nicomachean Ethics. London: Hackett Publishing, 1988.

2. Bentham J. Introduction to the Principles of Morals and Legislation (1789) (Burns JH, Hart DLA, eds). London: Methuen, 1982.

3. Chalmers AF. What is this Thing called Science? Buckingham: Open University, 1999.

4. Grossman LI. Endodontics 1776–1996: a bicentennial history against the background of general dentistry. J. Am. Dent. Assoc. 1976; 93: 78–87.

5. Hughes GJ. Aristotle on Ethics. London: Routledge, 2001.

6. Kant I. Foundations of the Metaphysics of Morals (1785). Indianapolis: Bobbs–Merrill, 1959.

7. Molander A, Caplan D, Bergenholtz G, Reit C. Improved root-filling quality among general dental practitioners educated in nickel titanium rotary instrumentation. Int. Endod. J. 2007; 40: 254–60.

8. Nussbaum M. Poetic Justice. The Literary Imagination and Public Life. Boston: Beacon Press, 1995.

9. Polanyi M. Personal Knowledge: Towards a Postcritical Philosophy. London: Routledge, 1958.

10. Ryle G. The Concept of Mind. London: Penguin, 1949.

11. Salehrabi R, Rotstein I. Endodontic treatment outcomes in a large patient population in the USA: an epidemiological study. J. Endod. 2004; 30: 846–50.

Part 1

The Vital Pulp

Chapter 2

The dentin–pulp complex: structures, functions and responses to adverse influences

Leif Olgart and Gunnar Bergenholtz

Introduction

The extent to which the dental pulp will sustain impairment in the clinical setting depends on its potential to oppose bacterial challenges and withstand injury by various forms of trauma. To understand the biological events that operate and most often prevent the pulp from suffering a permanent breakdown, the specific biological functions of both dentin and pulp under pathophysiological conditions will be addressed in this chapter. These two tissue components of the tooth form a functional unit that often is referred to as the dentin–pulp complex (Fig. 2.1).

Constituents and normal functions of the dentin–pulp complex

Dentin and dentinal tubules

Dentin provides elasticity and strength to the tooth that enable it to withstand loading forces by mastication and trauma. Dentin also elicits important defense functions aimed at preserving the integrity of the pulp tissue.

Under normal, healthy conditions, when dentin is covered by enamel and cementum, fluid in the dentinal tubules can contract or expand to impinge on the cells in the pulp in response to thermal stimuli applied on the tooth surface. Hence, dentin of the intact tooth can transform external stimuli into an appropriate message to cells and nerves in the pulp – a feature that is useful clinically to test its vital functions (see Chapter 14). A sensory transducer function triggered by elastic deformation is also in effect to detect overload resulting in reflex withdrawal and sharp transient pain.

Fig. 2.1 The soft tissue of the pulp is surrounded by dentin and enamel or cementum. Inset depicts the interface zone between dentin and pulp.

When enamel and cementum are damaged for any reason, the exposed dentinal tubules serve as pathways to the pulp for entry of potentially noxious elements in the oral environment including bacterial macromole-cules, which may provoke inflammation (4). The deeper the injury the more tubules become involved (). In the periphery there are about 20 000 tubules per square millimeter, each having a diameter of 0.5 μm. At the pulpal ends the tubular apertures occupy a greater surface area because the tubules converge centrally and become wider (2.5–3 μm) (20). Thus, at the inner surface of dentin there are more than 50 000 tubules per square millimeter. In root dentin, especially towards the apex, the tubules become more widely spaced. Also, in the pulpal portion of root dentin they are thinner and have a smaller diameter (ca. 1.5 μm). There are extensive branches between the tubules that allow intercommunication.