in
Endodontic
Retreatment
Stéphane Simon, DCD
Former Staff Physician
Department of Dental Surgery
University of Paris 7
Paris, France
Wilhelm-Joseph Pertot, DCD
Former Assistant Professor
Lecturer
Department of Dental Surgery
University of the Mediterranean Aix-Marseille II
Marseille, France
Foreword
Jean-Pierre Proust
Paris, Berlin, Chicago, Tokyo, London, Milan, Barcelona, Istanbul, São Paulo, Mumbai, Moscow, Prague, and Warsaw |
First published in French in 2007 by Quintessence International Paris
La reprise du traitement endodontique
ISBN 978-2-912550-59-0
© 2009 Quintessence International
Quintessence International
11 bis, rue d’Aguesseau
75008 Paris
France
All rights reserved. This book or any part thereof may not be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, or otherwise, without prior written permission of the publisher.
Design: STDI, Lassay-les-Châteaux, France
Printing and Binding: EMD, Lassay-les-Châteaux, France
Printed in France
Table of Contents
Cover | |
Table of Contents | |
Foreword | |
1 | Endodontic Failures and Indications for Retreatment |
When to Retreat? | |
Preoperative Considerations: To Retreat or Not to Retreat? | |
Prior to Starting Retreatment | |
Taking a History | |
Radiographic Examination | |
Conventional Retreatment or a Surgical Approach? | |
2 | Removal of Existing Restorations |
Should Existing Restorations Be Removed Routinely? | |
Removal of Coronal Restorations | |
Removal of Restorative Material and Posts | |
3 | Access, Removal of Obturation Materials, and Negotiation of Canals |
Improving Access | |
Canal Anatomy and Clinical Implications | |
Removal of Obturation Material | |
Management of Fractured Instruments | |
4 | Management of Perforations |
Factors Influencing Prognosis and Type of Treatment | |
Materials Used for Perforation Repair | |
Perforations in the Coronal Third | |
Furcation or Strip Perforations | |
Perforations of the Pulp Chamber Floor | |
Perforations of the Middle and Apical Thirds of the Canal | |
5 | Treatment of Teeth with Open Apices |
Immature Teeth | |
Treatment by Apexogenesis | |
Treatment by Apexification | |
Management of Other Cases with Open Apices | |
Alternative Treatment Options | |
6 | Prognosis and Retreatment |
Endodontic Disease and Its Management | |
Assessment of Periodontal Health | |
Prognosis of Endodontic Treatment and Retreatment | |
Factors that Can Interfere with Healing | |
Endodontic Surgery: An Adjunct to Treatment | |
Bibliography |
Foreword
It is a great honor to be asked by Wilhelm Pertot and Stéphane Simon to write the foreword for this book. I like the fact that this book is clinically relevant and addresses the challenges that we, as dentists, face on a daily basis—indications for more retreatments than pulpectomies, difficulties of managing the sequelae of trauma, and the problems associated with fractured instruments.
The practical focus of this book makes it a worthy addition to the Clinical Success series published under the guidance of Jean-Marie Korbendau. Having been his student in 1963 to 1964, I remember with gratitude the rigorous practical and theoretic education he provided. Each week he asked us to present a written account of our clinical experiences, and he placed as much importance on the style as on the content. Unless clearly expressed, even the most important ideas become unintelligible.
This new book is devoted to the most time-consuming phase of endodontics—retreatment. The step-by-step guide shows the clinician how to overcome obstacles such as blockages, perforations, and immature apices. In addition it details how to successfully prepare and fill canals to prevent bacterial proliferation, thereby avoiding a subsequent bacteremia with its potential complications. The persistence of bacteria in the root canal system—away from the blood vessels that constitute the police force of our immune system—makes it necessary for us to place root fillings that wall off the bacteria and prevent further spread of infection.
Every day, I apply the same techniques outlined in this book as diligently as I can. In follow-up assessment with patients treated 6 months previously, I find they have been cured of unilateral sinusitis and headaches. Cardiac patients who need treatment for a devitalized tooth but are scheduled for immediate surgery cannot afford to wait 6 months to check if the lesion is healing; I am now convinced that root canal treatment for a devitalized tooth presents no greater risk than extraction, provided that the treatment is conducted in line with the recommendations presented in this book and with the best possible disinfection procedures in place.
This book is complete yet concise and easy to consult before appointments when you realize an alternative treatment option might be simpler (eg, extraction, implant). The authors guide the clinician through routine endodontic retreatment and its myriad complications including perforations, blockages, fractured instruments, and pulpal necrosis in immature teeth.
Whether you are a practicing clinician or a student, this book will aid in professional development. It offers a wealth of information accumulated by two practitioners who have acquired enormous practical experience in the field of endodontics. They have an extensive knowledge of the literature as well as a thorough understanding of the materials involved.
I am grateful for this opportunity to thank them for the invaluable contribution they have made in helping practitioners overcome the difficulties that are, alas, all too frequently encountered in endodontic retreatment.
Jean-Pierre Proust, PU-PH
Endodontic Failures |
|
Indications for Retreatment | |
Endodontic treatment should fulfill a variety of objectives (Schilder, 1967 and 1974):
• Create a continuously tapering preparation from the crown to the apices
• Maintain the position of the apical foramen on the root surface
• Maintain the shape of the original canal as much as possible
• Keep the apical foramen as small as possible
• Use copious irrigation to ensure the root canal system is thoroughly cleaned and disinfected
• Obturate and seal the root canal system.
Although the procedures for endodontic treatment of a vital or necrotic pulp were first described decades ago, the number of unsatisfactory endodontic results remains rather high. Epidemiologic studies published over the past 20 years show that the number of inadequate treatments varies between 60% and 79%, with a failure rate (that is, cases where clinical symptoms or periapical lesions exist) of 22 % to 63 % (Boucher et al, 2002).
Endodontic retreatment can be defined as further treatment performed because the initial treatment was inadequate or the lesion failed to heal.
From a clinical standpoint, the four causes of failure are inherent within each stage of endodontic treatment (Ruddle, 2004) :
• Inadequate access cavity due to failure to appreciate the anatomy of the tooth; this hampers visibility, which in turn results in the following:
– Failure to detect accessory canals
– Difficulty in correctly preparing the canal because of instruments further restricting visibility or difficulty in visualizing the entire canal system
– Perforations in the coronal third of the tooth or in the pulp chamber floor
• Insufficient irrigation during canal preparation
• Improper use of instruments during preparation, which may result in the following:
– Alteration of the canal trajectory, which can cause obstructions and eventual perforations
– Blockages and subsequent loss of working length (obstruction by debris or a fractured instrument); this prevents irrigation of the whole root canal system
– Widening of the apical foramen, making controlled obturation impossible
• An error in fitting the gutta-percha cone, resulting in moisture contamination, a fault frequently associated with inadequate preparation of the apex; however, obturation material extruded through the apex is not in itself an indication for either orthograde or retrograde retreatment.
From a biologic standpoint, endodontic failure can result from improper preparation, disinfection, or obturation of the root canal network. Reinfection of the canal system resulting from a poor coronal seal could also lead to endodontic failure.
Irrespective of the technical inadequacies or errors, all endodontic failures are directly associated with the presence of bacteria and their toxins in the root canal system; these irritants migrate into the periodontal tissues by any route possible (eg, apical foramen, lateral canals, accessory canals).
The goals of endodontic retreatment remain the same as the goals of the initial treatment: elimination of bacteria and prevention of further bacterial contamination by means of a well-obturated canal and a coronal seal. Achieving these goals ensures long-term success with little chance of relapse or reappearance of pathology (Figs 1-1a and 1-1b).
Many endodontic failures can be attributed to inadequate training of the clinician and a lack of understanding of modern endodontic concepts and how to implement them. Resistance to change prevents many experienced practitioners from adopting new techniques, new instruments, and new materials; this, coupled with the misuse of unfamiliar equipment, contributes to a number of endodontic failures.
Endodontic treatment, when performed correctly, is predictable and enjoys a success rate above 95%. The same cannot be said for retreatment, in which access to canals can prove difficult, even dangerous, and in which negotiation of canals can be hampered by the following:
– Coronal restorations with large intracanal dowels
– Various canal filling materials such as hard and soft pastes, gutta-percha, or silver points
– Calcification of the apical portion of the canal as a result of inadequate preparation during initial treatment
– Iatrogenic causes including blockages, shoulders, ledges, perforations, and fractured instruments
Retreatment therefore necessitates the use of specific techniques and often proves complex and difficult.
When to Retreat?
A number of studies have shown that the decision to undertake endodontic retreatment is subject to both inter- and intrapractitioner variation. Agreement between practitioners on whether or not to retreat is rare (Aryanpour et al, 2000). The decision is often based on the individual practitioner’s personal criteria rather than on a set of universally recognized, objective criteria (Pagonis et al, 2000; Kvist and Reit, 2002).
Although it would be very difficult to produce universal guidelines to identify cases that should be retreated, a consensus does exist regarding certain situations that require endodontic retreatment (Friedman, 2002).
After rigorous clinical examination to eliminate any possible causes of failure that are nonendodontic in origin (eg, cracks or fractures, food packing, occlusal trauma, sinusitis, trigeminal neuralgia), endodontic retreatment should be undertaken in the following cases.
Clinical symptoms
Retreatment is indicated when clinical symptoms persist after initial treatment. Patients generally complain of spontaneous pain of variable intensity that is exacerbated by occlusal problems or during mastication. There may be signs of swelling, an abscess, or a fistula. Radiographic evidence of a lesion is not always present (Figs 1-2a and 1-2b).
At a clinical level, the following apply:
– Immediate postoperative pain that subsides within days is not necessarily an indication that the treatment will fail in the long term. Periodontal inflammation after endodontic treatment or retreatment is a common occurrence and is not a cause for concern unless it persists.
– Sensitivity in occlusion does not necessarily imply endodontic failure but may simply indicate a high spot; if that is the case, symptoms will disappear once the high spot has been reduced.
– Complaints of pain in a treated tooth brought on by changes in temperature (particularly cold) should make the operator first suspect the pain is referred from an adjacent tooth or elsewhere. If this possibility is eliminated, other potential causes should be investigated; there may be untreated canals or contact between metallic elements and vital tissue, such as a silver point projecting through the apex, which can lead to pain.
– Pain or sensitivity on chewing could be related to a cracked tooth or root fracture. To avoid unnecessary endodontic treatment on such a tooth, the differential diagnosis must be considered after taking a thorough pain history, performing periodontal probing, assessing the occlusion, and taking a radiograph (Pertot and Simon, 2003).
Radiographic evidence
In the absence of clinical symptoms, many practitioners prefer not to retreat a tooth even if a periapical lesion is evident radiographically (Hulsmann, 1994). The development or persistence of a periapical lesion after a monitoring period of several months signals endodontic failure and is an indication for retreatment. A periapical lesion results from bacterial infection and therefore needs to be treated (Figs 1-3a to 1-3c).
The practitioner must first determine how much time has passed since the initial treatment and then, if possible, should compare previous radiographs to check if the lesion is in fact healing; this is particularly important if both the root filling and the coronal restoration appear to be adequate. Although the first stages of healing can be seen radiographically 3 months postoperatively with the formation of bony trabeculae, complete healing of large lesions may take several years.
Cases where new coronal restorations are planned
When a new coronal restoration is planned, radiographic examination is necessary to assess any previous endodontic treatment on the tooth; if deemed technically inadequate, the root filling should be redone as a preventive measure (Machtou, 1993) (Figs 1-4a to 1-4c). The absence of a radiographic lesion on a tooth with an inadequate root filling does not indicate the absence of bacteria in the canal network. Teeth whose canals have been contaminated by bacteria can remain asymptomatic as long as the balance between the body’s defense system and the virulence of the bacteria is not altered. Disturbing this balance by instrumentation and crown preparation (impressions, post space preparation) can cause a lesion to develop where previously one did not exist (Figs 1-5a and 1-5b).
The objective of endodontic treatment or retreatment is to control the source of bacterial contamination, thereby tipping the balance in favor of the body’s defense system. In retreatment cases where the canal cannot be negotiated to the apex, the use of rubber dam, correct tapering of the canal, and copious irrigation are usually sufficient to stimulate healing. It is therefore important to retreat teeth with apparently inadequate root fillings even in the absence of clinical or radiographic signs of failure, in cases where new coronal restorations are planned.
If no new restoration is planned, however, and if there is a healthy periodontium, a good coronal seal, and absence of clinical or radiographic symptoms, practitioners should refrain from retreating and should only monitor the tooth, even if the root filling is clearly unsatisfactory (unless medical reasons dictate otherwise).
Cases where the coronal seal is deficient
Retreatment is indicated for any tooth where the access cavity has been inadequately sealed and has been open to the oral environment for a considerable period of time, even if the root filling seems adequate radiographically. Numerous studies over the past 10 years have demonstrated that if the coronal seal is deficient, bacteria can infiltrate and migrate down to the apex even when root canals are adequately filled. Although the reported time for this migration of bacteria varies from study to study, authors agree that the coronal seal is an important factor in the long-term success of root canal treatment. In vivo studies have shown that the first signs of periapical pathology can appear 4 months after treatment. These findings confirm the need to retreat all teeth where contamination has occurred and highlight the importance of restoring the tooth immediately after completion of endodontic treatment to ensure the best possible coronal seal.
For the same reasons, in complex cases where multiple teeth are prepared over several weeks, a good seal on temporary restorations is essential. After each root canal treatment, a definitive restoration must be placed as soon as possible. A provisional crown does not provide a good seal; bacterial contamination through the coronal aspect is inevitable until a definitive restoration is placed.
Preoperative Considerations: To Retreat
or Not to Retreat?
Technologic advances in instruments and materials (eg, ultrasonic instruments for endodontic use), combined with magnification devices (loupes and microscopes), allow the clinician to achieve optimal results with retreatment. Nevertheless, except in cases where the need for retreatment is clear, many other factors must be taken into consideration before making the decision to retreat a given tooth or to consider alternative treatment options.
Is the tooth strategically important and what are the alternatives?
Once a root filling is deemed to have failed, the clinician should evaluate the importance of the tooth and assess alternative treatment options, exploring the advantages and disadvantages of each with the patient. Endodontic retreatment is not an end in itself. With the materials now available, experienced clinicians can expect to obtain good results in the retreatment of most teeth; it is, however, essential to consider the value of the tooth in the overall treatment plan. Thus, before making a decision on retreatment, the clinician should assess the strategic importance of the tooth, the periodontal condition, the occlusion, and any associated pathology (eg, perforation, resorption), and should evaluate the likelihood of a successful long-term restoration (Figs 1-6a to 1-6c).
Periodontal assessment
Any factors that may influence the long-term viability of the tooth should be ascertained by periodontal probing, assessment of tooth mobility, evaluation of the crown-root relationship, and identification of any bony resorption. Careful periodontal probing is necessary to evaluate the quality of the epithelial attachment, especially in cases with furcation lesions. A lesion of endodontic origin with no fistula has a favorable prognosis even when the lesion is large (Figs 1-7a and 1-7b). Conversely, a lesion that communicates with the oral cavity via a fistula, following destruction of the epithelial attachment, has a far less favorable prognosis (Figs 1-8a and 1-8b).
Periodontal probing, combined with an occlusal assessment and often a radiograph, is essential when considering a differential diagnosis of root fracture. Many retreatment procedures (both coronal and surgical) are performed unnecessarily because an undetected root fracture was the actual cause of the problems. A fairly consistent pocket depth around the tooth suggests the problem is likely to be of periodontal origin; an increase in pocket depth at a particular point suggests a fracture has occurred (Figs 1-9a to 1-9c).
Restorability of the tooth
The objective in treating a tooth endodontically is to allow it to remain as a functional unit in the arch. A tooth that has extensive caries or that has broken down and has little function or value in the overall treatment plan should not be restored. A tooth with a caries lesion that extends subgingivally may need periodontal intervention first to restore the biologic width. Where possible, crown lengthening should be completed prior to retreatment; this creates more favorable conditions for each stage of treatment. For the endodontist, the crown lengthening makes it easier to place a rubber dam clamp and allows the tooth to be restored before treatment; in this way the four-walled access cavity creates a reservoir for the irrigant. Crown lengthening also enables placement of a stable temporary dressing that is capable of resisting occlusal forces and preventing bacterial leakage. In the phase following endodontic treatment, the visibility gained by crown lengthening simplifies the placement of the final restoration. This helps to ensure long-term periodontal health and, above all, makes a good coronal seal possible.
Surgery time required and cost-benefit ratio