Clinical Atlas of Retreatment in Endodontics [1 ed.] 1119509203, 9781119509202

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Clinical Atlas of Retreatment in Endodontics

Clinical Atlas of Retreatment in Endodontics Edited by Viresh Chopra, BDS, MDS

Course leader, Endodontology Senior Lecturer, Adult Restorative Dentistry Private practice limited to Microscopic Endodontics Oman Dental College Muscat, Sultanate of Oman

This edition first published 2021 © 2021 John Wiley & Sons Ltd All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by law. Advice on how to obtain permission to reuse material from this title is available at http://www.wiley.com/go/permissions. The right of Viresh Chopra to be identified as the author of the editorial material in this work has been asserted in accordance with law. Registered Offices John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, USA John Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, UK Editorial Office 9600 Garsington Road, Oxford, OX4 2DQ, UK For details of our global editorial offices, customer services, and more information about Wiley products, visit us at www.wiley.com. Wiley also publishes its books in a variety of electronic formats and by print-on-demand. Some content that appears in standard print versions of this book may not be available in other formats. Limit of Liability/Disclaimer of Warranty The contents of this work are intended to further general scientific research, understanding, and discussion only and are not intended and should not be relied upon as recommending or promoting scientific method, diagnosis, or treatment by physicians for any particular patient. In view of ongoing research, equipment modifications, changes in governmental regulations, and the constant flow of information relating to the use of medicines, equipment, and devices, the reader is urged to review and evaluate the information provided in the package insert or instructions for each medicine, equipment, or device for, among other things, any changes in the instructions or indication of usage and for added warnings and precautions. While the publisher and authors have used their best efforts in preparing this work, they make no representations or warranties with respect to the accuracy or completeness of the contents of this work and specifically disclaim all warranties, including without limitation any implied warranties of merchantability or fitness for a particular purpose. No warranty may be created or extended by sales representatives, written sales materials or promotional statements for this work. The fact that an organization, website, or product is referred to in this work as a citation and/or potential source of further information does not mean that the publisher and authors endorse the information or services the organization, website, or product may provide or recommendations it may make. This work is sold with the understanding that the publisher is not engaged in rendering professional services. The advice and strategies contained herein may not be suitable for your situation. You should consult with a specialist where appropriate. Further, readers should be aware that websites listed in this work may have changed or disappeared between when this work was written and when it is read. Neither the publisher nor authors shall be liable for any loss of profit or any other commercial damages, including but not limited to special, incidental, consequential, or other damages. Library of Congress Cataloging-in-Publication Data applied for [ISBN: 9781119509202] Cover Design: Wiley Cover Image: © Viresh Chopra Set in 9.5/12pt StixTwoText by Straive, Pondicherry, India 10  9  8  7  6  5  4  3  2  1

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Contents Foreword  ix Preface  xi Acknowledgments  xiii List of Contributors  xv List of Abbreviations  xvii About the Companion Website  xix

Introduction to endodontic retreatment  1 Sanjay Miglani, Fugen Dagli Comert, Swadheena Patro, and Viresh Chopra

1 Clinical Case 1 – Perforation repair: A case of repair of pulpal floor perforation caused by excessive cutting of the floor of the pulp chamber  5 Mohammad Hammo 2 Clinical Case 2 – Instrument separation: A case of surgical removal of a fractured instrument  10 Abhinay Agarwal 3 Clinical Case 3 – A case of retreatment of Tooth 16: Bypass of ledges and broken instrument  17 Garima Poddar 4 Clinical Case 4 – Instrument retrieval: A case of fractured instrument at the apical third of the mandibular molar  23 Jojo Kottoor 5 Clinical Case 5 – Perforation repair with instrument retrieval: Management of  multiple endodontic mishaps  32 Padmanabh Jha 6 Clinical Case 6 – Management of strip perforation and fractured instrument  38 Zaher Al Taqi 7 Clinical Case 7 – Management of root canal treatment failure case with missed lateral canal anatomy and inadequate obturation  45 Antonis Chaniotis

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Contents

8 Clinical Case 8 – Management of a case with faulty cast post and asymptomatic lateral periodontitis  51 Antonis Chaniotis 9 Clinical Case 9 – Management of a case with endo-perio lesion following a previous root canal treatment  58 Antonis Chaniotis 10 Clinical Case 10 – Management of a failed root canal treatment with silver cone obturation and fractured instrument  64 Antonis Chaniotis 11 Clinical Case 11 – Management of a failed root canal treated maxillary molar with selective root treatment  69 Gergely Benyőcs 12 Clinical Case 12 – Guided endodontics and its application for non-surgical retreatments: Retreatment of a maxillary anterior tooth using static guidance  79 Gergely Benyőcs 13 Clinical Case 13 – Management of pulpal floor perforation with periapical lesion in the mesial root  99 Zaher Al Taqi 14 Clinical Case 14 – Management of root canal treatment failure with missed canal anatomy and inadequate obturation  108 Eugen Buga 15 Clinical Case 15 – Management of root canal treatment failure with inadequate obturation, hidden fractured instrument and ledge formation in a severely curved mandibular molar  114 Eugen Buga 16 Clinical Case 16 – Management of root canal treatment with an instrument fracture in a mandibular molar  121 Viresh Chopra 17 Clinical Case 17 – Management of a mandibular molar with fractured instrument extending in the periapical area  128 Zaher Al Taqi 18 Clinical Case 18 – Management of root canal treatment failure with inadequate obturation and apically calcified canals  134 Viresh Chopra

Contents

19 Clinical Case 19 – Management of root canal treatment failure with inadequate obturation and missed canals  140 Viresh Chopra 20 Clinical Case 20 – Management of root canal treatment failure with inadequate obturation, unusual distal root anatomy and suspected ledge formation in a mandibular molar  147 Eugen Buga 21 Clinical Case 21 – Management of root canal treatment failure with inadequate obturation and faulty post placement  154 Viresh Chopra 22 Clinical Case 22 – Management of root canal treatment failure with inadequate obturation, multiple perforations, fractured instrument and ledge formation in maxillary right first molar  161 Viresh Chopra 23 Clinical Case 23 – Management of root canal treatment failure with inadequate obturation, fractured instrument and periapical lesion in mandibular left first molar  172 Viresh Chopra 24 Clinical Case 24 – Retreatment of Tooth 21  180 Garima Poddar 25 Nonsurgical versus surgical retreatment: Decision making  187 Meetu Ralli Kohli and Bekir Karabucak Index  201

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Foreword Retreating an endodontic case can be quite challenging and the editor, Dr. Viresh Chopra, has masterfully categorized all the permutations of retreatment into different chapters with the emphasis on illustrating every point with his contributors. The chapter on surgical vs nonsurgical endodontic retreatment provides a good discipline in treatment‐planning. Case selection (i.e., good judgement) is a critical issue because not every case previously treated (and failing) should be retreated; sometimes extraction is indeed the better choice. The exciting new surgical endodontic technique using a 3D template for guided osteotomy and retro sealing apexes is explained and illustrated here very well—this novel approach will become much more popular once endodontists have the equipment and training to perform these conservative and effective surgical procedures. I applaud Dr. Chopra for editing this richly illustrated book that should be in the library of every endodontist… and a round of applause to the contributors! Stephen Cohen M.A., D.D.S., FICD, FACD Diplomate, American Board of Endodontics

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Foreword Contemporary endodontology is reliant on the sharing of evidence-based knowledge and this atlas adroitly brings together the work of a number of international contributors who are congratulated for collaboratively addressing many of the clinical considerations and challenges faced during endodontic retreatment. The inclusion of QR codes and links to the numerous helpful clinical video clips on the companion website is of significant additional benefit in demonstrating a range of operative procedures. As editor Dr Chopra is to be congratulated for adeptly harmonising this well illustrated resource that will no doubt serve as an excellent reference guide for general practitioners with an interest in Endodontology and in particular to postgraduate students and endodontists who wish to enhance and refine their approach to endodontic retreatment. Rahul Arora MSc, BDS, LDS, FFGDP, FCGDent Dean, Oman Dental College

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Preface When Dr. Viresh Chopra asked me to provide the Preface for his Clinical Atlas of Retreatment in Endodontics, I was very surprised. After all, the Preface is done traditionally by the author himself or herself. However, he had compelling reasons for inviting me, he said. A few years ago, he discussed with me the idea of producing a book on Endodontics. We debated the shape, the form, and the content of the intended book and identified the features that would be of most benefit to busy clinicians in practice. So the Clinical Atlas on Retreatment was born. Retreatment is one of the most challenging areas in Endodontics. By getting contributions from a group of eminent endodontists, this Atlas has enhanced its appeal and its value by providing a broader insight into the management of these failures successfully. Here is the collective clinical experience and the wisdom of fifteen endodontists. There are twenty‐five cases presented in this Atlas, ranging from a perforation of the pulpal floor to cases with multiple failures such as inadequate obturation, fractured instrument, ledge formation in a severely curved root canal and multiple perforations. The cases are varied in their origins, nature, and complexity. The rich illustrations with their accompanying text make it easier to understand the management of these cases by the experts. Dr. Chopra once told me that if his students cannot understand what he is trying to teach, then he has failed. Therefore, he spends a lot of time planning what and how he teaches. The same philosophy has been applied to this book. Please read the Atlas and see for yourself. You will not be disappointed. DYD Samarawickrama BDS, PhD, FDSRCS, FHEA, FCGDP, FODC Emeritus Professor of Conservative Dentistry Queen Mary University of London, UK

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Acknowledgments ­

“If I have seen further than others, it is by standing upon the shoulders of giants.” Sir Isaac Newton

Thank you is a small word which would never completely convey the sense of gratitude and regards which I feel for each of the following colleagues who have made this Clinical Atlas of Retreatment in Endodontics, first edition a reality. We all start and stay in a state of rest, or of uniform motion in a straight line, unless motivated, inspired or compelled to become active by forces/people around us. Editing this book has really been an eye opener and made me learn a lot and appreciate the presence of everyone’s support around me. First and foremost, my sincere gratitude to Prof DYD Samarawickrama for his belief in me and motivating me to make this dream a reality. Also, I would like to thank my Dean Dr. Rahul Arora, Vice Dean Dr. Nutayla Al Harthy and Prof. Mohammed Ismaily for trusting in this project and supporting me to make this dream a day. To start is easy but to carry on is difficult. My sincere thanks to Dr. Aylin Baysan, for always sending me that positive energy and force that keep me going at all times. I would like to take this opportunity to thank each one of my teachers who have helped me in my growth as an endodontist. With folded hands I bow forward to my Gurus Dr. S. Datta Prasad, Dr.  Pravin Kumar, Dr. Himanshu Aeran, Dr. Vineeta Nikhil, Dr. Himanshu Sharma and Dr. Shibani Grover. I would like to specially thank few people who have played a major role in my growth as an academician and as a clinician: Dr. Anil Kohli for always blessing me with his advice, Dr. Sanjay Miglani for being my mentor and a constant source of inspiration and support at every stage, Dr. K.S Banga for always motivating me to do better, Dr. V. Gopikrishna for always inspiring me with his wisdom and giving me one take home message in every interaction, and Dr. Vivek Hegde for always pushing me to give the best to my patients. The actual strength of this book is the clinical contributions by eminent researchers and clinicians from across the world. I thank each one for accepting my invitation to contribute and for their kindness and generosity in sharing their knowledge and expertise. I thank all the leading dental companies who trusted in this project and supported me for it. Thank you, Carl Zeiss, Zirc, FKG Dentaire, Coltène/Whaledent and bioMTA for your support. I would like to thank the wonderful team at WILEY BLACKWELL for their genuine passion and professionalism for making this dream a reality. Thank you, Susan Engelken, Miss. Loan Nguyen, Tanya McMullin, Copyeditor Holly Regan‐Jones and Mustaq Ahamed for your support.

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Acknowledgments

A special thanks to Sumit Dubey, Ashwani Mishra and Pankaj vats for being my friends and their timely advices. My sincere thanks to each one of the following people at my place of work for helping me in various ways during the genesis of this book: Oman Dental College: Prof. Fugen Dagli Comert; my wonderful team of assistants Mr. Allan Renz Rodriguez, Ms. Christel Santisteban, Mr. Rony C. Joy, Ms. Mariamol Seethy Karammel, Ms. Bharati V. Bangera, Mr. Ibrahim for their everlasting support. Finally, I owe my exceptional gratitude to my parents for their blessings, brother Dr. Vishal Chopra for his timely advice, wife Dr. Harneet Chopra, and children for their unflinching support. V. Chopra

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List of Contributors Abhinay Agarwal, BDS, MDS Professor, Department of Conservative Dentistry and Endodontics Teerthanker Mahaveer Dental College and Research Centre Moradabad, Uttar Pradesh, India Zaher Al Taqi, BDS, MDS Private practice Riyadh, Saudi Arabia Antonis Chaniotis, DDS, MDS Private practice limited to Microscopic Endodontics Athens, Greece Gergely Benyőcs, DDS, MDS Private practice limited to Microscopic Endodontics Budapest, Hungary Eugen Buga, DDS, MDS Private practice limited to Microscopic Endodontics Chisinau, Republic of Moldova

Oman Dental College Muscat, Oman Mohammad Hammo, BDS, DESE Chairman of British Academy of Implants and Restorative Dentistry Private practice limited to Endodontics Jordan and Bahrain Padmanabh Jha, BDS, MDS Professor, Department of Conservative Dentistry and Endodontics Subharti Dental College, Swami Vivekanand Subharti University Meerut, Uttar Pradesh, India Bekir Karabucak, DMD, MS Chair and Professor of Endodontics, Director of Postgraduate Endodontic Program, and Director of Advanced Dental Education School of Dental Medicine, University of Pennsylvania Philadelphia, PA, USA

Viresh Chopra, BDS, MDS Senior Lecturer, Adult Restorative Dentistry, Course Leader, Endodontology Oman Dental College Muscat, Oman

Meetu Ralli Kohli, BDS, DMD Clinical Associate Professor of Endodontics, Department of Endodontics School of Dental Medicine, University of Pennsylvania Philadelphia, PA, USA

Fugen Dagli Comert, DDS, PhD Professor, Adult Restorative Dentistry, and Specialist Endodontist

Jojo Kottoor, BDS, MDS Private practice limited at Root Canal Point Kerala, India

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List of Contributors

Sanjay Miglani, MDS, FISDR Professor, Department of Conservative Dentistry and Endodontics Faculty of Dentistry, Jamia Millia Islamia University New Delhi, India Swadheena Patro, BDS, MDS Professor, Department of Endodontics Kalinga Institue of Dental Sciences Patia, Bhubaneswar, India

Garima Poddar, BDS Senior Consultant, Dental Department Shanti Memorial Hospital Pvt. Ltd. Cuttack, Odisha, India Faculty Diploma in endodontic program, Universitat Jaume I (UJI), Castelló, Spain

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List of Abbreviations­ MTA – Mineral Trioxide Aggregate PDL – Periodontal ligament IOPAR – Intraoral periapical radiograph IANB – Inferior Alveolar Nerve Block NaOCl – Sodium Hypochlorite EDTA – Ethylenediaminetetraacetic acid GP – Gutta Percha CBCT – Cone beam computed tomography PUI – Passive ultrasonic irrigation

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­About the Companion Website This book is accompanied by a companion website: https://www.wiley.com/go/chopra/retreatment The website include: ●●

Videos

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Introduction to endodontic retreatment Sanjay Miglani, Fugen Dagli Comert, Swadheena Patro, and Viresh Chopra There has been massive growth in endodontic treatment in recent years. The main aim of root canal treatment is to disinfect and shape the root canal system and seal it in three dimensions to prevent reinfection of the tooth [1, 2]. Although initial root canal therapy is known to be a predictable procedure with a high degree of success [3–6], failures can occur after treatment. Literature has reported failure rates of 14–16% for initial root canal treatment [3, 7]. Lack of healing is due to persistent intraradicular infection residing in previously uninstrumented canals, dentinal tubules or in the complex irregularities of the root canal system [8–11]. The extraradicular causes of endodontic failures include periapical actinomycosis [12], a foreign body reaction due to extruded endodontic materials [13, 14], an accumulation of endogenous cholesterol crystals in the apical tissues [15] and an unresolved cystic lesion [16, 17]. The term ‘retreatment’ is widely used in endodontics to denote a new intervention aimed at retaining the tooth in the oral cavity  [18]. Previously treated teeth with persistent periapical lesion(s) might be preserved with non-surgical retreatment or endodontic surgery, assuming the tooth is restorable and periodontally sound, and the patient wants to retain the tooth. When a decision is made to preserve the tooth, the clinician and patient face the challenge of selecting the treatment with the most beneficial long-term outcome. Evidence-based dentistry recommends selection of alternative treatment options based on the best available evidence [19]. Intuitively, a considered medical procedure is regarded as meaningful only if it is thought to bring about some benefit to the patient. Accordingly, the consequences of treating or not treating the disease in question must be at the core of the clinical decision-making process.

I.1 ­Definition According to the Glossary of Endodontic Terms of the American Association of Endodontists, retreatment [20] is defined as: A procedure to remove root canal filling materials from the tooth, followed by cleaning, shaping and obturation of the root canals. The indications for ‘root canal retreatment’ given by the European Society of Endodontology [21] are: ●●

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teeth with inadequate root canal filling with radiological findings of developing persisting apical periodontitis (apical lesion) teeth with inadequate root canal filling when the coronal restoration requires replacement or the coronal dental tissue is to be bleached.

Clinical Atlas of Retreatment in Endodontics, First Edition. Edited by Viresh Chopra. © 2021 John Wiley & Sons Ltd. Published 2021 by John Wiley & Sons Ltd. Companion website: www.wiley.com/go/chopra/retreatment

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  Introduction to endodontic retreatment

The above definitions, though correct, describe only one clinical situation of reintervention – when there is need to remove the previous root canal filling material. Carr [22] proposed an updated and comprehensive definition of reintervention: Endodontic retreatment is a procedure performed on a tooth that underwent a previous attempt at definitive treatment resulting in a condition that requires further endodontic intervention to achieve a successful outcome.

I.2­  Rationale for retreatment Root canal system anatomy plays a significant role in endodontic success and failure [23–25]. It contains branches that communicate with the periodontal attachment apparatus furcally and laterally, and often terminate apically into multiple portals of exit [26]. Therefore, any opening from the root canal system (RCS) to the periodontal ligament space should be thought of as a portal of exit (POE) through which potential endodontic breakdown products may pass [27, 28]. There can be various causes for endodontic failures such as: ●● ●● ●● ●●

missed canals pathological or iatrogenic perforations inadequate obturations inadequacies in shaping, cleaning and obturation, iatrogenic events, or reinfection of the RCS when the coronal seal is lost after completion of root canal treatment [29–32].

Regardless of all the causative factors, the final cause for failure is leakage and bacterial contamination due to inadequate debridement, disinfection or sealing of the RCS. Success can be achieved in previously failed endodontic cases by confirming the restorability of the tooth in question, careful treatment planning and proper execution of the treatment plan. In addition, it depends upon the skill of the individual operator performing the procedure.

I.3­  Aim of endodontic retreatment The aim of retreatment is to perform an endodontic treatment that can render the treated tooth functional and comfortable again, allowing complete repair of the supporting structures. Before starting the retreatment, it is profoundly important to consider all interdisciplinary treatment options in terms of time, cost, prognosis and potential for patient satisfaction. It is important to evaluate the endodontic failures so a decision can be made among non-surgical retreatment, surgical retreatment or extraction [33, 34, 35]. Retreatment is classified into two major groups [18]. ●●

●●

Non-surgical or conventional retreatment: the retreatment procedure is done through the root canals. Used in cases where the initial treatment is incomplete or presence of inadequate treatments diagnosed as failures. Surgical retreatment: the treatment procedure is carried out after surgical exposure of the apical portion of the tooth.

Clinicians should always opt for non-surgical retreatment over the surgical option unless a successful outcome cannot be achieved by a non-surgical approach.

  ­Reference

With the advent of magnification and newer retreatment technologies, non-surgical retreatment procedures take care of mechanical failures, previously missed canals or radicular subcrestal fractures. Non-surgical endodontic retreatment procedures have enormous potential for success if the guidelines for case selection are respected and the most relevant technologies, best materials and precise techniques are utilized [21–23]. This book focuses on a variety of failed endodontic cases that have been treated successfully with different non-surgical as well as surgical approaches. The aim of this book is to discuss: ●● ●● ●● ●● ●● ●●

different possible reasons for failure of endodontic treatment different ways to avoid iatrogenic errors while performing a root canal treatment different approaches taken to successfully retreat endodontically failed cases do’s and don’ts during an endodontic treatment do’s and don’ts during an endodontic retreatment the decision-making process between surgical and non-surgical retreatment options.

R ­ eferences   1 Schilder H. Cleaning and shaping the root canal. Dent Clin North Am 1974;18: 269–96   2 Schilder H. Filling root canals in three dimensions. Dent Clin North Am 1967;723–44.   3 Torabinejad M, Anderson P, Bader J, et al. Outcomes of root canal treatment and restoration, implant-supported single crowns, fixed partial dentures, and extraction without replacement: a systematic review. J Prosthet Dent 2007;98:285–311.   4 de Chevigny C, Dao TT, Basrani BR, et al. Treatment outcome in endodontics: the Toronto study – phase 4: initial treatment. J Endod 2008;34:258–63.   5 Sjogren U, Hagglund B, Sundqvist G, Wing K. Factors affecting the long-term results of endodontic treatment. J Endod 1990;16:498–504.   6 Salehrabi R, Rotstein I. Endodontic treatment outcomes in a large patient population in the USA: an epidemiological study. J Endod 2004;30:846–50.   7 Ng YL, Mann V, Rahbaran S, Lewsey J, Gulabivala K. Outcome of primary root canal treatment: systematic review of the literature – part 2: influence of clinical factors. Int Endod J 2007;41:6–31.   8 Nair PN. On the causes of persistent apical periodontitis: a review. Int Endod J 2006; 39:249–81.   9 Davis SR, Brayton SM, Goldman M. The morphology of the prepared root canal: a study utilizing injectable silicone. Oral Surg Oral Med Oral Pathol 1972;34:642–8. 10 Peters OA, Barbakow F, Peters CI. An analysis of endodontic treatment with three nickel-titanium rotary root canal preparation techniques. Int Endod J 2004;37: 849–59. 11 Stropko JJ. Canal morphology of maxillary molars: clinical observations of canal configurations. J Endod 1999;25:446–50. 12 Tronstad L, Barnett F, Cervone F. Periapical bacterial plaque in teeth refractory to endodontic treatment. Endod Dent Traumatol 1990;6:73–7. 13 Koppang HS, Koppang R, Solheim T, Aarnes H, Stolen SO. Cellulose fibers from endodontic paper points as an etiological factor in postendodontic periapical granulomas and cysts. J Endod 1989;15:369–72. 14 Nair PN, Sjogren U, Krey G, Sundqvist G. Therapy-resistant foreign body giant cell granuloma at the periapex of a root-filled human tooth. J Endod 1990;16:589–95. 15 Nair PN. Cholesterol as an aetiological agent in endodontic failures: a review. Aust Endod J 1999;25:19–26.

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1 6 Simon JH. Incidence of periapical cysts in relation to the root canal. J Endod 1980;6: 845–8. 17 Nair PN, Pajarola G, Schroeder HE. Types and incidence of human periapical lesions obtained with extracted teeth. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;81:93–102. 18 Zuolo M, Kherlakian D, De Mello Jr J,  Carvalho M. Fagundes M. (2014). Reintervention in Endodontics Quintessence Publishing, Batavia, IL. 19 Torabinejad M, Bahjri K. Essential elements of evidenced-based endodontics: steps involved in conducting clinical research. J Endod 2005;31:563–9. 20 American Association of Endodontists. Glossary of contemporary terminology for endodontics. 2020 www.aae.org/specialty/clinical-resources/glossary-endodontic-terms/ 21 European Society of Endodontology. Quality guidelines for endodontic treatment: consensus report of the European Society of Endodontology. Int Endodontic J, 39:921–30, 2006. 22 Carr GB. Retreatment. In: Cohen S, Burns R (eds) Pathways of the Pulp, 7th edn, St Louis, Mosby Inc., 1998. 23 Scianamblo MJ. Endodontic failures: the retreatment of previously endodontically treated teeth, Revue D’Odonto. Stomatologie 17:5, pp. 409–23, 1988. 24 Hess W, Zürcher E. The Anatomy of the Root Canals of the Teeth of the Permanent and Deciduous Dentitions, William Wood & Co, New York, 1925. 25 Ruddle CJ. Endodontic failures: the rationale and application of surgical retreatment, Revue D’Odonto. Stomatologie 17:6, pp. 511–69, 1988. 26 Goon WWY. Managing the obstructed root canal space: rationale and techniques, J Calif Dent Assoc 19:5, pp. 51–60, 1991. 27 Glick DH, Frank AL. Removal of silver points and fractured posts by ultrasonics. J Prosth Dent 1986;55:212–15. 28 Bertrand MF, Pellegrino JC, Rocca JP, Klinghofer A, Bolla M. Removal of Thermafil root canal filling material. J Endod 23:1, pp. 54–57, 1997. 29 West JD. The relation between the three-dimensional endodontic seal and endodontic failure. Masters thesis, Boston University, 1975 30 Torabinejad M, Ung B, Kettering JD. In vitro bacterial penetration of coronally unsealed endodontically treated teeth. J Endod 16:12, pp. 566–69, 1990. 31 Alves J, Walton R, Drake D. Coronal leakage: endotoxin penetration from mixed bacterial communities through obturated, post-prepared root canals. J Endod 24:9, pp. 587–91, 1998. 32 Southard DW. Immediate core buildup of endodontically treated teeth: the rest of the seal, Pract Periodont Aesthet Dent 11:4, pp. 519–26, 1999. 33 Stabholz A, Friedman S. Endodontic retreatment- case selection and technique. Part 2: treatment planning for retreatment. J Endod 14:12, pp. 607–14, 1988. 34 Allen RK, Newton CW, Brown CE. A statistical analysis of surgical and non-surgical endodontic retreatment cases. J Endod 15:6, pp. 261–66, 1989. 35 Kvist T, Reit C. Results of endodontic retreatment: a randomized clinical study comparing surgical and nonsurgical procedures. J Endod 25:12, pp. 814–17, 1999.

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1 Clinical Case 1 – Perforation repair: A case of repair of pulpal floor perforation caused by excessive cutting of the floor of the pulp chamber Mohammad Hammo

Introduction to the case: pulpal floor perforation caused by excessive cutting of the floor of the pulp chamber.

1.1 ­Patient information ●● ●● ●●

Age: 30 years old. Gender: female. Medical history: non-contributory.

1.2 ­Tooth ●● ●●

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Identification: mandibular left first molar (Tooth 36). Dental history: discomfort due to impingement of food inside her molar. Previous treatment done on this tooth 1 year ago. Clinical examination findings: deep decay, tooth was filled with food remnants, no mobility, no pain to percussion. After cleaning the tooth, big perforation was noted and bleeding also. Preoperative radiological assessment: deep decay and lesion at furcation area due to perforation (Figure 1.1). Diagnosis (pulpal and periapical): previously initiated root canal therapy with asymptomatic apical periodontitis.

1.3 ­Treatment plan ●●

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First visit: local anaesthesia, rubber dam isolation, magnification (dental operative microscope), conventional access cavity, identification of orifices of the canals, placing cotton pellets inside them, stopping the bleeding physically with cotton pellet (Figure 1.2). Treatment plan for management of the endodontic mishap: applying MTA at the furcation area, then inserting a wet cotton pellet over MTA, temporary filling (Figure 1.3).

Clinical Atlas of Retreatment in Endodontics, First Edition. Edited by Viresh Chopra. © 2021 John Wiley & Sons Ltd. Published 2021 by John Wiley & Sons Ltd. Companion website: www.wiley.com/go/chopra/retreatment

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1  Clinical Case 1

Figure 1.1  Preoperative radiograph showing radiolucency in the furcation area.

Figure 1.2  Clinical picture showing the pulpal floor perforation.

1.5 ­Follow-u

Figure 1.3  Radiograph showing MTA placed on the pulpal floor.

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●● ●● ●●

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Second visit: removing temporary filling and cotton pellets, Check the condition of MTA (hardness), canal preparation with rotary files. Irrigation protocol (solution and technique): 5.25% NaOCl; passive sonic irrigation. Final irrigation protocol: 17% EDTA (syringe irrigation) for 1 minute. Obturation (materials and technique): zinc oxide-based sealer (SealiteTM Ultra) and gutta-percha; warm vertical compaction. Permanent filling (Figures 1.4 and 1.5).

1.4 ­Technical aspects Key points to be taken care of while managing the endodontic mishap. ●● ●●

Stop bleeding before applying MTA. Place wet cotton pellet over MTA and wait at least 4 hours to let it set.

1.5 ­Follow-up Follow for 2.5 years. The follow-up radiograph shows formation of a bony trabecular pattern. Clinical and radiographic healing is evident on follow-up visits (Figure 1.6).

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1  Clinical Case 1

Figure 1.4  Radiograph showing master cone verification after biomechanical preparation of root canals.

Figure 1.5  Radiograph showing obturation along with intact MTA.

1.7  ­How can this endodontic

mishap be avoided

Figure 1.6  Follow-up radiograph showing healing in the furcation area.

1.6 ­Learning objectives ●● ●● ●●

How to approach a tooth with pulpal floor perforation. The size and time of perforation do not justify extraction. The priority is always for perforation repair, so do it as soon as possible.

1.7 ­How can this endodontic mishap be avoided? ●● ●● ●● ●●

Overdrilling should be avoided. Location of canal orifices should be done with an endodontic explorer. Once the operator feels a drop in the pulp chamber, no more vertical cutting should be done. Use of safe-ended, non-cutting burs is recommended (e.g. Endo-Z burs).

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2 Clinical Case 2 – Instrument separation: A case of surgical removal of a fractured instrument Abhinay Agarwal

Introduction to the case: case of separated instrument referred for removal. The instrument separated in the mesiolingual canal 1 month ago at a private clinic. The instrument slipped in the periapical area while attempts were being made to remove it. The patient complained of pain in the tooth since then.

2.1 ­Patient information ●● ●● ●●

Age: 21 years old. Gender: female. Medical history: non-contributory.

2.2 ­Tooth ●● ●●

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●●

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Identification: mandibular right first molar (Tooth 46). Dental history: patient reported pain in her mandibular right first molar for 1 month. She gave a history of previous root canal treatment of the same tooth 1 month back. Clinical examination findings: Tooth 46 was restored with a temporary filling material. The tooth was tender on examination. Preoperative radiological assessment: IOPAR revealed a radiopacity in the coronal one-third area suggestive of temporary filling material followed by radiolucency in the middle and cervical thirds of the crown suggestive of an endodontic access cavity. The radicular aspect showed a marked opacity in the mesial root middle to apical third suggesting a separated endodontic instrument in the mesiolingual canal (Figure  2.1). There was ill-defined periapical radiolucency with loss of lamina dura and widening of the PDL space suggestive of chronic apical periodontitis. Diagnosis (pulpal and periapical): previously initiated therapy along with a separated endodontic instrument in the mesiolingual canal, with symptomatic apical periodontitis.

Clinical Atlas of Retreatment in Endodontics, First Edition. Edited by Viresh Chopra. © 2021 John Wiley & Sons Ltd. Published 2021 by John Wiley & Sons Ltd. Companion website: www.wiley.com/go/chopra/retreatment

2.3 ­Treatment pla

Figure 2.1  Preoperative intraoral periapical radiograph with separated instrument.

2.3 ­Treatment plan ●●

●● ●● ●● ●●

Preliminary procedures: the patient was advised to undergo non-surgical re-root canal treatment (NSRRCT). After informed consent was obtained, NSRRCT was initiated. The patient was given local anaesthesia (IANB) and the tooth was isolated using rubber dam, the access cavity was refined and cleaned for any residual caries and straight-line access was achieved. The separated instrument was bypassed successfully (Figure 2.2) and then after working length determination, chemomechanical preparation was performed, and an attempt was made to retrieve the instrument, during which the instrument slipped into the periapical area (Figure 2.3). Irrigation (solution and technique): normal saline, 5% NaOCl (syringe irrigation) for 5 minutes. Final irrigation protocol: 17% EDTA (syringe irrigation) for 3 minutes. At this point, it was thought best to obturate and wait for any signs and symptoms. Obturation (material and technique): Endomethasone N sealer and gutta-percha. Single cone technique was used in the mesial canals and a lateral condensation was done for the distal canal (Figure 2.4).

The patient was informed about the mishap, and further follow-up was planned. After about a month, the patient again reported with pain and tenderness. At this point, she was advised Figure 2.2  Intraoral periapical radiograph showing instrument bypass.

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2 Clinical Case 2

Figure 2.3  Intraoral periapical radiograph showing periapically extruded separated instrument.

Figure 2.4  Intraoral periapical radiograph showing obturation.

for periapical surgery and extraction with periapical curettage. All further complications were discussed with the patient and consent for periapical surgery was obtained from her. Blood investigations were advised. After the reports were found to be normal, periapical surgery was decided upon.

2.4 ­Surgical procedure ●●

●●

●●

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A full-thickness mucoperiosteal flap was raised extending from the mesial aspect of the first mandibular premolar to the distal aspect of the second mandibular molar (Figure 2.5). A cavity was drilled using a straight handpiece and round bur just below the mesial aspect of the mandibular first molar approximating to the apical third of the mesial root to approach the periapical area of the mesial root (Figure 2.6). To confirm the correct position, a hand instrument was placed inside the cavity and a radiograph was obtained (Figure 2.7). After confirming the correct position, granulation tissue was removed using a curette following which the instrument was retrieved (Figures  2.8 and  2.9). A clinical picture of the retrieved

2.4 ­Surgical procedur

Figure 2.5  Incision and flap reflection.

Figure 2.6  Trephination at the site.

Figure 2.7  Intraoral periapical radiograph showing the location of the extruded instrument.

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2 Clinical Case 2

Figure 2.8  Curettage of the operating site.

Figure 2.9  Retrieved instrument.

●● ●●

instrument was taken (Figure 2.10). To confirm complete removal, radiographs were obtained with and without placement of the hand instrument (Figure  2.11). After curettage was completed, the flap was approximated and sutured using 3-0 silk suture (Figure 2.12). At 5 days, the patient was asymptomatic and the sutures were removed. The patient has remained asymptomatic throughout the follow-up period and healing in the periapical area can be appreciated.

2.4 ­Surgical procedur

Figure 2.10  Intraoral periapical radiograph showing instrument retrieval.

Figure 2.11  Immediate postoperative intraoral periapical radiograph.

Figure 2.12  Flap approximation and suturing of the operated site.

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2 Clinical Case 2

2.5 ­Technical aspects Endodontic mishaps are inevitable and instrument separation is one of the unwanted happenings which every endodontist will encounter in their career. It is very important to minimize this mishap. Also, management of the separated instrument is an important and difficult part of endodontic practice. In this case, after successfully bypassing the instrument, the instrument slipped into the periapical area during retrieval. This emphasizes how important it is to attempt these procedures very carefully and to determine whether an instrument should always be retrieved even if it has been successfully byepassed.

2.6 ­Follow-up The patient was followed at 1 month (Figure 2.13), 6 months and 1 year (Figure 2.14).

2.7 ­Learning objectives The reader should be able to: ●● ●● ●● ●● ●●

diagnose a separated instrument learn about retreatment possibilities make a decision on retrieving or bypassing the fractured instrument make a decision between NSRCT and SRCT understand the importance of recall in such cases. Figure 2.13  Postoperative intraoral periapical radiograph after 1 month.

Figure 2.14  Postoperative intraoral periapical radiograph after 1 year.

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3 Clinical Case 3 – A case of retreatment of Tooth 16: Bypass of ledges and broken instrument Garima Poddar

Introduction to the case: a case of endodontic retreatment of a tooth with underobturation, ledges and bypass of broken fragment of instrument.

3.1 ­Patient information ●● ●● ●●

Age: 18 years old. Gender: female. Medical history: non-contributory.

3.2 ­Tooth ●● ●●

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Identification: maxillary right first molar (Tooth 16). Dental history: patient complaint of pain in maxillary right posterior region for 1 month. Pain was dull and aching, continuous in nature, and relieved on taking medication. Clinical examination findings: on clinical examination the tooth was tender to percussion and the crown structure of the tooth showed decay (Figure 3.1). Preoperative radiological assessment: on intraoral periapical radiograph, the tooth showed the following (Figure 3.2): –– underobturation in the mesiobuccal canal –– incomplete shaping and underobturation in the distobuccal canal –– separated instrument fragment in the apical third of the distobuccal canal –– caries still remaining in the coronal part of the tooth. Diagnosis: pulpal – previously treated; periapical – symptomatic apical periodontitis.

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3  Clinical Case 3

Figure 3.1  Preoperative clinical picture.

Figure 3.2  Preoperative radiograph showing inadequate obturation and fractured instrument in the distobuccal canal.

3.3 ­Treatment plan ●●

Preliminary procedures –– Local anaesthesia: 2% lignocaine with adrenaline injection was infiltrated buccally using a 30 gauge needle and greater palatine block was given to anaesthetize the tooth. –– Rubber dam isolation: the tooth was isolated using rubber dam.

3.3 ­Treatment pla

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–– Magnification: the treatment was performed under magnification. A dental operating microscope was used throughout the procedure. –– Remaining caries, unsupported and fragile tooth structures were removed. Then, the old restoration was removed. –– Pre-endo build-up was carried out and access was refined. Treatment plan for management of the endodontic mishap and repair procedure –– Removal of old obturation material from the canals. The tooth was found to be obturated with single gutta-percha cones in all three canals. Removal of GP cones was performed easily with manual K-files, and the GP cones came out in toto in single full-length pieces from all three canals (Figure 3.3). –– Bypass of the separated instrument fragment in the apical third of the distobuccal canal (Figure 3.4). Since the broken instrument fragment was in the apical third of the canal and was present beyond the curvature of the distobuccal canal, it was decided to go for a bypass of the fragment. This was done using K-files of number 10, 15, 20, and 25, by finding a catch behind the broken fragment and then going further apically in a picking motion. Once the no. 25 K-file was loose in the canal, shaping of the distobuccal canal was done using a 2Shape® TS1 file (25–4%) from Micro-Mega. While attempting bypass of the broken fragment, a ledge was also discovered in the distobuccal canal so bypass of both ledge and instrument fragment was carried out. –– Undershaped and underobturated mesiobuccal canal: the mesiobuccal canal was found to be short of working length and also it was undershaped. This was rectified. The length was negotiated to proper working length and then it was shaped with 2Shape files. The MB2 canal was not found, even when troughed under magnification.

Figure 3.3  Gutta-percha cones removed from the root canals.

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3  Clinical Case 3

Figure 3.4  Bypassing the fractured instrument with a no. 10 manual K-file and verifying it on the radiograph.

–– Palatal canal: after removal of GP material, coronal flaring was done using One Flare® files from Micro-Mega. –– Glide path was established using a One G® file from Micro-Mega. The canal was properly shaped using 2Shape files (TS1 and TS2) and then 30–6% of HERO Shaper® file.

3.3.1  Shaping ●● ●● ●●

Mesiobuccal canal: shaped with One Flare, One G and 2Shape files. Distobuccal canal: One Flare, 8 k, 10 k, 15 k, 20 k, 25 k, TS1 files. Palatal canal: One Flare, One G, 2Shape and finally 30–6% HERO Shaper files.

3.3.2  Irrigation (solution and technique) ●● ●● ●● ●● ●●

5.25% NaOCl: throughout shaping and bypassing. Distilled water. 17% EDTA: 1 mL per canal per minute, ultrasonic activation. Distilled water. 5.25%NaOCl: internal heating, ultrasonic activation (four cycles repeated).

3.3.3  Obturation Master cone fit is verified with a radiograph (Figure 3.5). Epoxy resin-based sealer (AH Plus®) and GP; warm vertical compaction. A lateral canal was also filled up in the mesiobuccal canal (Figure 3.6).

3.4 ­Technical aspects Some important aspects of an endodontic retreatment procedure include the following. ●●

●● ●●

Understanding the shortcomings of the previous RCT which could have led to treatment failure. Magnification is a helpful tool, especially in retreatment cases. While bypassing, one of the most important tools is patience. It is a good idea to keep a spacedout appointment for a case of bypass.

3.6 ­Learning objective

Figure 3.5  Verifying the fit of master cones up to the full working length on the radiograph.

Figure 3.6  Final obturation radiograph with bypassing of the ledge as well as the fractured instrument in the distobuccal canal.

●●

Do not ever force a file while attempting a bypass in the canal as this might lead to a second file separation. In this particular case, there was an additional ledge which had to be bypassed. Gentle watch winding and picking motions along with copious irrigation and recapitulation helped.

3.5 ­Follow-up One-year follow-up showed healing and that the tooth was completely asymptomatic and functional (Figure 3.7).

3.6 ­Learning objectives ●● ●●

●●

Removal of all the carious parts in the coronal tooth structure is important. Working length estimation and reconfirming working length time and again during the procedure help. Bypass requires patience and perseverance. Following the protocols of bypass helps.

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3  Clinical Case 3

Figure 3.7  One-year follow-up radiograph with postendodontic full coverage restoration showing healing of the periapical tissues.

3.7 ­How can this endodontic mishap be avoided? ●● ●●

●●

Coronal flaring helps. Establishing a glide path with glide path files helps in maintaining patency throughout the working length. Proper irrigation after withdrawing each shaping file from the canal helps in clearing off the debris simultaneously, and thus helps to avoid ledge formation or even the possibility of instrument separation due to wedging of instruments in the canal.

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4 Clinical Case 4 – Instrument retrieval: A case of fractured instrument at the apical third of the mandibular molar Jojo Kottoor

Introduction to the case: separated instrument retrieval from the apical third of a mandibular premolar and management of complex apical third trifurcation.

4.1 ­Patient information ●● ●● ●●

Age: 69 years old. Gender: male. Medical history: patient is diabetic and on oral medication.

4.2 ­Tooth ●● ●●

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Identification: mandibular left first premolar (Tooth 34). Dental history: patient was referred for Re-RCT and separated file management in Tooth 34. He reported with intermittent pain in his left lower and upper teeth. Clinical examination findings: Tooth 34 capped with a metal-ceramic crown and tender to vertical percussion. Periodontal probing around the tooth and mobility were within physiological limits. Preoperative radiographic assessment: intraoral periapical radiograph: #34 – inadequate endodontic treatment, suspected missed anatomy in the apical third. Separated instrument fragment in the apical third, suspected apical to canal bifurcation. Sharp mesial apical curvature (Figure 4.1). Diagnosis (pulpal and periapical): previously treated Tooth 34  with symptomatic apical periodontitis. Instrument separation in Tooth 34.

4.3 ­Treatment plan ●●

Preliminary procedures: ;ocal anaesthesia was induced using 1.8 mL 2% lidocaine with 1:200 000 epinephrine. Under rubber dam isolation, access opening was done with trans-metal bur. A dental operating microscope was used throughout the procedure. The primary aim was to gain

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4  Clinical Case 4

Figure 4.1  Intraoral periapical x-ray: #34 – inadequately endodontically treated, missed anatomy in the apical third; separated instrument fragment in the apical third, apical to canal bi/trifurcation and periapical lesion; sharp mesial apical curvature; #35 – inadequate endodontic treatment, short of apex, with periapical lesion.

●●

●●

access (Figure 4.2) and remove the gutta-percha up to the separated file (Figures 4.3 and 4.4), remove the separated file and explore the root canal system further for variable root canal anatomy (Figure 4.5). Treatment plan for management of the endodontic mishap: gutta-percha was removed using an ultrasonic tip (ET 20; Satelec® Acteon), no. 10 04% microdebrider (Dentsply Maillefer) and H-file, exposing the coronal aspect of the separated file (Figure  4.6). A modified no. 2 and 3  Gates Glidden drill (Dentsply Maillefer) was used to prepare a staging platform coronal to the fractured instrument. This allowed the use of ultrasonic tips to trephine dentine circumferentially around the fragment. Under the highest magnification, activation (30 seconds interval) with the ET 25 ultrasonic tip (Satelec Acteon) was used to trephine the dentine around the fragment to expose the coronal 2 mm of the separated file. The canal was irrigated with 17% EDTA to cool the operating field and flush dentine debris out of the canal (Figure 4.7). After approximately 11 minutes, the fragment loosened and came out (Figures 4.8, 4.9 and 4.10). Under the highest magnification, a staging platform was prepared around the file using the ET 25 ultrasonic tip. Intermittent ultrasonic activation with 17% EDTA was given around the file fragment, and it popped out of the canal to the orifice. Endodontic mishap repair procedure: the root canal was negotiated with a no. 10 K-file and a working length radiograph was taken for Tooth 34 (Figure  4.11). The radiograph also confirms the apical bifurcation that has not yet been located (mesial half). Between the two

4.3 ­Treatment pla

Figure 4.2  Coronal access through the metal ceramic crown showing a single cone gutta-percha obturation.

Figure 4.3  Unfilled lateral spaces around the single cone gutta-percha.

Figure 4.4  Gutta-percha removed to the middle third of the root.

Figure 4.5  Gutta-percha removed to the the apical third of the root.

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4  Clinical Case 4

Figure 4.6  After complete removal of guttapercha, visualization of the separated file at the apical third.

Figure 4.7  Intraoperative radiograph showing removal of the gutta-percha and access to the separated file.

Figure 4.8  Retrieval of the separated fragment after creating a staging platform and ultrasonic activation with 17% EDTA irrigation.

4.3 ­Treatment pla

Figure 4.9  Magnified view of the retrieved segment of the rotary file.

Figure 4.10  Intraoperative x-ray confirming complete retrieval of the separated fragment. A temporary filling was placed and the patient was recalled after a week.

●●

endodontic visits, the patient had visited his general dentist, who had initiated restorative work for a fixed prosthesis spanning Teeth 35–38. A screw post with dead space of 1–2 mm was seen on Tooth 35. A second working length radiograph demonstrated the complexity of the mesial half of the bifurcation (Figure 4.12). A third canal was also located and an apex locator was used for the working length of the third canal because of its close proximity to the other two canals. Canal preparation (or retreatment procedure): the distal canal was instrumented with ProTaper Universal till F3 (Dentsply Sirona) while the middle and mesial canals were instrumented with an Ni-Ti K-type hand file up to size 20.

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4  Clinical Case 4

Figure 4.11  Working length x-ray confirming the length gained with Tooth 34. The radiograph also confirms the apical bifurcation that has as yet been unlocated (mesial half). Between the two endodontic visits, the patient had visited his general dentist, who had initiated restorative work for a fixed prosthesis spanning Teeth 35–38. A screw post with dead space of 1–2 mm was seen on #35.

Figure 4.12  A second working length radiograph demonstrating the complexity of the mesial half of the bifurcation. A third canal was also located and an apex locator was used for the working length of the third canal because of its close proximity to the other two canals. Chemomechanical instrumentation of the root canal system was done using hand/ rotary and dynamic irrigation with IrriSafe ultrasonic tips.

4.4  ­Removing or bypassing the fractured instrument: decision makin

Figure 4.13  Postoperative radiograph demonstrating root canal filling material into the complexities of the apical third of the tooth. Note the trifurcation at the apical third. Obturation was done using the squirting obturation technique.

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Irrigation (solution and technique): 3% NaOCl was used as the working irrigant throughout the shaping procedure with a 31 G needle. After shaping, ultrasonic activation (IrriSafeTM; Acteon) five times for 30 seconds per canal with 3% NaOCl followed by 17% EDTA. 2% Clorhexidine (syringe irrigation) for 1 minute. Normal saline was used as an intermediate irrigant. Final irrigation protocol: the canals were irrigated with 2 mL of 95% ethanol. It was left in place for 10 seconds followed by removal of excess ethanol with a single paper point before squirting. Obturation: calcium hydroxide-based sealer (SealApexTM) and gutta-percha; squirting (Figure 4.13).

4.4 ­Removing or bypassing the fractured instrument: decision making When an instrument fractures in the root canal system, a decision has to be made to leave, bypass or remove the fragment, the choice being based on an assessment of the potential benefit of removal compared with the risk of complications. The rationale behind the removal of the fragment in this case was that, unless the obstruction in the canal is removed, further

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4  Clinical Case 4

exploration and disinfection of the complex apical anatomy will not be possible and the outcome will be significantly reduced. However, one should keep in mind that removal of the separated instrument from the apical third of the root canal needs high magnification under rubber dam isolation, clinical skill, time and supporting instruments. In addition, the technique would lead to heat production, root weakening, risk of perforation and postoperative fracture, thereby reducing the long-term prognostic value of the tooth. In multirooted teeth, it is recommended that a cotton wool plug/Teflon should be placed in the other canal orifices to prevent the removed segment lodging in another canal. The lowest effective power setting on the ultrasonic device should be used to avoid further fracture of the fragment or the expensive ultrasonic tip. Intermittent activation (not more than 10–20 seconds) and irrigation are imperative to reduce heat production within the canal. A K-type U-file attached to an E1/ED1 ultrasonic tip will be more versatile (large array of file sizes) and more economic than the regular endodontic tips specifically designed for instrument retrieval.

4.5 ­Follow-up See Figure 4.14. Figure 4.14  Follow-up radiograph at 13 months showing periapical healing.

4.7  ­How can this endodontic mishap be avoided

4.6 ­Learning objectives ●● ●● ●●

Suspect complex apical splits in mandibular premolars. Enhanced visualization via a dental operating microscope is imperative. Choose the technique that will give a favourable prognosis.

4.7 ­How can this endodontic mishap be avoided? ●● ●● ●● ●● ●● ●● ●● ●● ●● ●●

Read the preoperative radiograph properly. Straight line access to all canals Look for prefracture signs. Limit the number of files used. Acquire knowledge on torque, speed, and time. Create a proper glide path. Avoid screw-in effect or taper lock. Instrument in wet environment. Precurve the files wherever necessary. Avoid a hybrid technique.

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5 Clinical Case 5 – Perforation repair with instrument retrieval: Management of multiple endodontic mishaps Padmanabh Jha

Introduction to the case: a case of furcal perforation repair caused by excessive cutting of the floor of the pulp chamber. In addition to the perforation, the following endodontic mishaps were also managed: ●● ●●

fractured instrument in the distal canal a missed canal in the mesial root was located.

5.1 ­Patient information ●● ●● ●●

Age: 22 years old. Gender: female. Medical history: a history of asthmatic attacks, for which she was taking medication for the last 6 months.

5.2 ­Tooth ●● ●●

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Identification: mandibular left first molar (Tooth 36). Dental history: history of root canal treatment done around a year before. Episodes of pain on and off for the last 3 months. Pain and difficulty chewing in relation to mandibular left posterior region for the last 7 days. Clinical examination findings: faulty and loose full-coverage restoration in relation to Tooth 36. The tooth was tender to percussion. Preoperative radiological assessment: inadequately done root canal treatment with a separated instrument in the distal canal, a suspected pulpal floor perforation, a suspected missed canal in the mesial root and an underfilled canal with radiolucencies around the periapical area of both mesial and distal roots and the furcation area (Figure 5.1). Diagnosis (pulpal and periapical): failed root canal treatment with chronic apical abscess.

Clinical Atlas of Retreatment in Endodontics, First Edition. Edited by Viresh Chopra. © 2021 John Wiley & Sons Ltd. Published 2021 by John Wiley & Sons Ltd. Companion website: www.wiley.com/go/chopra/retreatment

5.3 ­Treatment pla

Figure 5.1  Preoperative radiograph showing furcal perforation, inadequate obturation, fractured instrument and periapical radiolucency.

5.3 ­Treatment plan ●●

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Preliminary procedures: the faulty and loose full-coverage restoration was removed. Then, a cotton pellet present in the access cavity was removed. Isolation was achieved with a combination of cotton rolls and saliva ejectors. Endodontic access cavity modification was carried out (Figure 5.2). Treatment plan for management of the endodontic mishap: modify the endodontic access cavity and locate the missed canal. Disinfect and seal the perforation and attempt to bypass the separated instrument in the distal canal. Adequately clean and shape the canals and place intracanal medicament. Obturate the tooth when it becomes asymptomatic. Endodontic mishap repair procedure. –– Endodontic access cavity modified with Endo-Z bur. Magnifying loupes with 3.5× magnification are used to locate the missed canal. Removal of previous root canal filling material with ProTaper retreatment files (D1, D2, and D3). The fractured instrument was bypassed with a no. 10 K-file and working length was determined (Figure 5.3). Sequential instrumentation was done using rotary files until size F3 ProTaper. MTA was used to repair the perforation in the furcal area. –– Irrigation (solution and technique): 3% sodium hypochlorite and 17% EDTA used alternately, with irrigant activation by sonic activation using the EndoActivator for 30 seconds after use of every instrument.

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5  Clinical Case 5

Figure 5.2  Clinical picture showing removal of the crown, removal of the cotton pellet from the access cavity and modification of the access cavity.

Figure 5.3  Radiograph showing location of the canals, working length determination and bypassing of the fractured instrument.

–– Final irrigation protocol: 2% chlorhexidine along with sonic activation using the EndoActivator for 1 minute. –– Obturation (material and technique): AH PlusTM used as sealant and gutta-percha as core material. Obturation done with a combination of lateral compaction and warm vertical compaction techniques (Figure 5.4).

5.6 ­Learning objective

Figure 5.4  Radiograph showing repair of the perforation and obturation of the root canals up to the working length. Bypassing of the fractured instrument can be seen in the distal canal.

5.4 ­Technical aspects ●●

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The perforation was debrided by copiously irrigating the area with normal saline followed by 2% chlorhexidine. After locating the canals and blocking the orifices with gutta-percha points, resorbable gel was condensed in the perforation area to act as the matrix, followed by the use of MTA to seal the perforation.

5.5 ­Follow-up ●●

After 4 months’ follow-up, the patient was asymptomatic. Radiographs show healing of the periapical area and decrease in the size of radiolucency in the furcation area (Figures 5.5 and 5.6).

5.6 ­Learning objectives ●● ●●

Use of magnification is essential to locate missed canals. Before sealing the perforation, proper debridement of the area is essential for better outcomes.

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5  Clinical Case 5

Figure 5.5  Four-month follow-up radiograph showing healing in the furcation area as well as the periapical area around the distal canal.

Figure 5.6  Clinical picture showing full-coverage permanent restoration and healing of the buccal vestibule area at 4-month follow-up.

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After debriding the perforation site, examine the area with adequate magnification (loupes or microscope) to rule out the presence of any foreign object or debris. Use of appropriate perforation repair material is required to treat the endodontic mishap.

5.7  ­How can this endodontic

mishap be avoided

5.7 ­How can this endodontic mishap be avoided? ●●

●● ●● ●● ●● ●●

Properly study the preoperative radiograph for the angulation of the tooth, position and size of the pulp chamber. Alignment of bur penetration for both depth and angulation can be confirmed with radiographs. Use safe-ended burs (e.g. Endo-Z) to extend the access cavity once you reach the pulp chamber. Overuse of endodontic files should be avoided to decrease the incidence of fracture of instruments. Copious irrigation and lubrication should be used to avoid instrument separation. Sequential use of instruments is necessary to clean and shape the canals.

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6 Clinical Case 6 – Management of strip perforation and fractured instrument Zaher Al Taqi

Introduction to the case: a case of strip perforation repair caused by inadequate straight-line endodontic access. In addition to the perforation, the following endodontic mishap was also managed: ●●

fractured instrument in the distal canal.

6.1 ­Patient information ●● ●● ●●

Age: 22 years old. Gender: female. Medical history: not significant.

6.2 ­Tooth ●● ●●

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Identification: mandibular right first molar (Tooth 46). Dental history: history of root canal treatment done around a year before. Episodes of pain on and off since the treatment was completed. Pain and difficulty in chewing in relation to mandibular right posterior region for the last few days. Clinical examination findings: faulty restoration in relation to #46. The tooth was tender to percussion. Preoperative radiological assessment: inadequately done root canal treatment with a separated instrument in the mesial canal, inadequate obturation with presence of sealer in the suspected strip perforation area. Radiolucent changes can be seen in the furcation area (Figure 6.1). Diagnosis (pulpal and periapical): failed root canal treatment with apical periodontitis.

Clinical Atlas of Retreatment in Endodontics, First Edition. Edited by Viresh Chopra. © 2021 John Wiley & Sons Ltd. Published 2021 by John Wiley & Sons Ltd. Companion website: www.wiley.com/go/chopra/retreatment

6.3 ­Treatment pla

Figure 6.1  Preoperative radiograph showing suspected strip perforation, inadequate obturation, fractured instrument and radiolucency along the mesial wall in the furcation area.

6.3 ­Treatment plan ●●

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Preliminary procedures: local anaesthesia to be performed, followed by isolation of the tooth with rubber dam. The core build-up to be removed and older gutta-percha to be located and removed. Perforation site to be located (Figure 6.2). Treatment plan for management of the endodontic mishap. –– Modify the endodontic access cavity to achieve a straight-line access. –– Removal of older root canal filling from the canals. –– Locate the site of strip perforation (Figure 6.2). Disinfect and seal the perforation. –– Locate the fractured instrument (Figure 6.3). Attempt to remove the separated instrument in the mesial canal. –– Adequately clean and shape the canals and place intracanal medicament. –– Obturate the tooth when it becomes asymptomatic. Endodontic mishap repair procedure. –– Calcium hydroxide dressing was removed and the perforation site was clearly visible under the microscope. –– After the removal of the older GP with retreatment files, the fractured instrument was clearly visible under the microscope. –– Loosening of the fractured instrument was done with the help of thin ultrasonic tips used on the inner wall of the canal. Care was taken not to touch the strip perforation site, as this would enlarge the perforation. Once the instrument was loose, loop extractors were used to catch it and bring it out of the canal (Figures 6.4 and 6.5). –– Sequential instrumentation was done using rotary files until size F3 of protaper. Irrigation (solution and technique): 3% sodium hypochlorite and 17% EDTA used alternately and irrigant activation by sonic activation using the EndoActivator for 30 seconds after use of every instrument. Final irrigation protocol: 2% chlorhexidine along with sonic activation using the EndoActivator for one minute.

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6  Clinical Case 6

Figure 6.2  Clinical picture showing the perforation site after removal of the calcium hydroxide dressing.

Figure 6.3  Clinical picture showing location of the fractured instrument under the microscope.

Figure 6.4  A loop retractor is used to catch and extract the instrument after it becomes loose in the canal following the use of ultrasonics.

6.5 ­Follow-u

Figure 6.5  Removal of the fractured instrument.

●●

●●

●●

Obturation (material and technique): partial obturation technique was used to obturate the apical third by gutta-percha plug with the help of System B heat carrier (Figures 6.6 and 6.7). This would prevent gutta-percha from spreading into the strip perforation. Strip perforation repair: after apical plug obturation with GP, MTA was condensed over the apical GP and toward the perforation site until the orifice level was reached. Once the perforation was repaired, other root canals were retreated successfully with sequential instrumentation and obturation (Figure 6.8). Removal of instrument, obturation and perforation repair were confirmed with a postoperative radiograph (Figure 6.9).

6.4 ­Technical aspects ●●

●●

●●

●●

The perforation was debrided by copiously irrigating the area with normal saline followed by 2% chlorhexidine. Care needs to be taken not to enlarge (touch) the strip perforation area while using ultrasonic tips for removal of the fractured instrument. The perforation site should not be touched with instruments as it might cause excessive bleeding and hamper vision while working. Use of a microscope for magnification is mandatory in such cases.

6.5 ­Follow-up ●●

Two-year follow-up. The patient was asymptomatic. Radiograph shows healing and decrease in the size of radiolucency in the furcation area (Figure 6.10).

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6  Clinical Case 6

Figure 6.6  Preparation of GP as an apical plug to obturate the part of the root canal apical to the strip perforation.

Figure 6.7  Obturation of the apical part of the canal with GP. This segment of GP will act as an apical plug.

Figure 6.8  Closure of the strip perforation site with MTA. Obturation of the other canals after sequential instrumentation and thorough cleaning and shaping.

6.6 ­Learning objective

Figure 6.9  Immediate postoperative radiograph showing removal of the fractured instrument, obturation of the root canals and closure of the strip perforation with MTA.

Figure 6.10  Two-year follow-up radiograph showing complete healing of the perforation site.

6.6 ­Learning objectives ●● ●● ●●

●●

Use of magnification is essential to see the perforation site as well as the fractured instrument. Removal of the instrument to be performed strictly under high magnification. First, clearly visualize the fractured instrument and then loosen the instrument and use copious irrigation to facilitate its removal from the canal. Avoid overcutting of dentinal walls for removal of the fractured instrument.

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6  Clinical Case 6 ●● ●● ●●

●●

Avoid touching the perforation site during removal of the instrument. Before sealing the perforation, proper debridement of the area is essential for better outcomes. After debriding the perforation site, examine the area with adequate magnification (loupes or microscope) to rule out the presence of any foreign object or debris. Use of appropriate perforation repair material is required to treat the endodontic mishap.

6.7 ­How can this endodontic mishap be avoided? ●●

●● ●● ●● ●● ●●

Properly study the preoperative radiograph for the angulation of the tooth, position and size of the pulp chamber. Straight-line endodontic access cavity is necessary. Overuse of endodontic files to be avoided to decrease the incidence of fracture of instruments. Copious irrigation and lubrication should be used to avoid instrument separation. Sequential use of instruments is necessary to clean and shape the canals. Correct angulation to be maintained throughout the cleaning and shaping procedure.

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7 Clinical Case 7 – Management of root canal treatment failure case with missed lateral canal anatomy and inadequate obturation Antonis Chaniotis

Introduction to the case: case of lateral periodontitis lesions associated with a previously inadequate root canal treatment. Short filling and missed lateral anatomy failure.

7.1 ­Patient information ●● ●● ●●

Age: 40 years old. Gender: male Medical history: non-contributory.

7.2 ­Tooth ●● ●● ●●

●●

●●

Identification: right mandibular second premolar (Tooth 45). Dental history: chief complaint: percussion painful. Referral note: short root canal treatment. Clinical examination findings: percussion and palpation painful. Periodontal probing was within normal limits. Negative response to cold vitality testing. Preoperative radiological assessment: the two-dimensional periapical radiograph revealed a previously treated tooth with an obturation of the root canal system remaining short of the radiographic apex. No periapical radiolucency could be detected in the preoperative two-dimensional periapical radiograph (Figure 7.1). Evaluation of a preexisting CBCT examination revealed an apical radiolucency as well as two lateral lesions (Figure 7.2). Diagnosis (pulpal and periapical): the pulpal diagnosis was consistent with a previously treated tooth. The periapical diagnosis was consistent with symptomatic apical and lateral periodontitis.

7.3 ­Treatment plan ●●

Preliminary procedures: buccal infiltration anaesthesia was administered. The tooth was isolated with rubber dam. Access was achieved with diamond burs under magnification provided by a six-step operating microscope.

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7  Clinical Case 7

Figure 7.1  Periapical radiograph showing the previously treated tooth with obturation of the root canal system remaining short of the radiographic apex. No periapical radiolucency can be detected on the radiograph.

(a)

●●

(b)

Figure 7.2  (a,b) CBCT examination revealed an apical radiolucency as well as two lateral lesions.

Treatment plan for management of the endodontic mishap: the coronal gutta-percha was removed with Gates Glidden burs and rotary retreatment files. No solvent was used as it was judged unnecessary. The proper length was regained and verified with an electronic apex locator. The canal was enlarged to a 60/04 size. Disinfection was achieved with positive syringe irrigation of 5% solution of NaOCl. After canal enlargement, some gutta-percha remnants were seen under magnification firmly attached in the canal dentinal walls. The canal was flooded with 17% EDTA for 5 minutes and then rinsed with NaOCl 5%. Alternate use of EDTA and NaOCl during retreatment can facilitate the debonding of well-attached remaining obturation materials. For removal

7.3 ­Treatment pla

Figure 7.3  Specially designed microexcavator instruments used for removal of gutta-percha remnants from the canal walls.

●●

●●

of the gutta-percha remnants from the canal walls, specially designed microexcavator instruments were used (Figure 7.3). Endodontic mishap repair procedure: after removal of all the gutta-percha remnants, an attempt was made to negotiate the possible pathways of communications from the canal wall to the lateral lesions. The exact location of the lateral lesions was assessed from the CBCT. A stiff endodontic hand file (D-Finder) was precurved with an endobender and the silicon stopper of the file was marked to correspond to the direction of the bend. The precurved file was inserted inside the enlarged canal and the tip of the file was directed toward the location of the lateral canal entrance (Figure 7.4). Negotiation of the lateral canals was verified with a periapical radiograph (Figure 7.5). The objective of this technique is to keep the entrance of the lateral extensions to the root canal system patent for the disinfection process to be effective and for the obturation material to flow inside these lateral pathways. Canal preparation (or retreatment procedure): after removal of the bulk material of the previous obturation, the single main canal was enlarged with rotary controlled memory files up to 60/04 apical enlargement. The two lateral canals were not shaped but were kept patent in order to be incorporated in the chemical disinfection process.

Figure 7.4  (a,b) Use of precurved file to evaluate the lateral anatomy of the canal.

(a)

(b)

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7  Clinical Case 7

(a)

(b)

Figure 7.5  (a,b) Attempt to negotiate the lateral anatomy of the root canal.

●● ●● ●●

●●

Irrigation (solution and technique): 5% NaOCl; passive ultrasonic irrigation (3 × 20 seconds). Final irrigation protocol: 17% EDTA (syringe irrigation) for 3 minutes. Obturation (material and technique): epoxy resin-based sealer (AH PlusTM) was used along with gutta-percha as the core obturating material. The technique used was warm vertical compaction (Figure 7.6). Additional information: both lateral canals were visualized after the three-dimensional obturation of the root canal system (Figure 7.6).

7.4 ­Technical aspects The internal anatomy of human teeth is complicated, consisting of a central main part and multiple lateral extensions. Failure to incorporate the lateral canal system in the disinfection process might result in persistent disease. The cleaning and shaping procedure during retreatment should address both the main and the lateral canal systems.

7.5 ­Follow-up The 3 years follow-up clinical and radiographic examination revealed an asymptomatic tooth and uneventful healing. The extruded sealer remained unaltered. Healing was verified in the CBCT examination that was undertaken in order to monitor a surgical procedure in the contralateral side (Figure 7.7).

7.5 ­Follow-u

(a)

(b)

Figure 7.6  (a,b) Obturation of the root canal. Sealer can be seen flowing through the lateral anatomy.

(a)

(b)

(c)

(d)

(e)

Figure 7.7  (a–e) CBCT images for 3-year follow-up confirming the flow of sealer through the lateral canals and thereby obturating the missed lateral anatomy. Healing of the lateral lesions can also be seen on the images.

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7  Clinical Case 7

7.6 ­Learning objectives The reader should understand: ●● the complexity of the root canal system ●● the limitations of two-dimensional imaging ●● the importance of incorporating the lateral extensions of the root canal system in the disinfection process during retreatment.

7.7 ­How can this endodontic mishap be avoided? During initial treatment, the astute clinician always bears in mind that we are not dealing with a canal – we are dealing with a complicated canal system with lateral extensions in which bacteria can spread and remain unaffected by treatment procedures. It is a challenge for the specialty to develop techniques that will facilitate the three-dimensional disinfection process of all the root canal system extensions. Scouting of the lateral canal walls is an essential step in the accomplishment of three-dimensional disinfection.

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8 Clinical Case 8 – Management of a case with faulty cast post and asymptomatic lateral periodontitis Antonis Chaniotis

Introduction to the case: an asymptomatic lateral periodontitis associated with a cast post.

8.1 ­Patient information ●● ●● ●●

Age: 50 years old. Gender: female. Medical history: non-contributory.

8.2 ­Tooth ●● ●●

●●

●●

●●

Identification: left first mandibular premolar (Tooth 34). Dental history: monitoring of a random radiographic finding of a lateral radiolucency associated with a previously treated tooth with cast post and crown. Four years later, the tooth became percussion painful. Chief complaint: cannot touch the tooth. Clinical examination findings: percussion and palpation painful and grade 2 mobility. Periodontal probing was within normal limits. Preoperative radiological assessment: two-dimensional periapical radiographs revealed a previously treated mandibular premolar associated with a mesially located lateral radiolucency. The radiograph revealed cast post restoration, adequate obturation length and a void between the post and the apical gutta-percha plug. After 4 years’ monitoring of the radiographic finding, the size of the lateral radiolucency increased (Figure 8.1). Diagnosis (pulpal and periapical): pulpal diagnosis was consistent with previous root canal treated tooth. Periapical diagnosis was consistent with symptomatic lateral periodontitis.

8.3 ­Treatment plan ●●

Preliminary procedures: buccal infiltration anaesthesia was administered. The PFM crown was removed with the WAMkey® device. A lateral opening was drilled in the coronal one-third of the crown (Figure  8.2). The appropriate WAMkey was selected to fit perfectly through the

Clinical Atlas of Retreatment in Endodontics, First Edition. Edited by Viresh Chopra. © 2021 John Wiley & Sons Ltd. Published 2021 by John Wiley & Sons Ltd. Companion website: www.wiley.com/go/chopra/retreatment

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8  Clinical Case 8

(a)

(b)

5/2008

(c)

8/2009

(d)

6/2010

11/2012

Figure 8.1  (a–d) Radiographs showing faulty cast post with a gap between the cast post and obturation. The developing lateral lesion can also be seen in the subsequent radiographs from 2008 to 2012.

●●

●●

lateral opening with its long diameter. Once the device reached the occlusal center of the crown, it was rotated CW and the crown was lifted, exposing the cast core (Figure 8.3). Two grooves were created mesially and distally to the cast core. Special care was taken to keep the drilling more centred toward the core material, minimizing dentinal tissue removal. After adequate width of the grooves was achieved, two WAM X prongs were fitted in place. A silicon ring was placed underneath the prongs to protect the tooth structure. The WAM X forceps was fitted in the prongs and small movements were initiated. After every 10 short strokes, the cast post was vibrated with an ultrasonic tip. Ultrasonic energy was delivered with interrupted activation. After another 10 strokes, the cast post and core were removed with a corkscrew approach (Figure 8.4). Treatment plan for management of the endodontic mishap: removal of the cast post revealed the apical third of the canal. A rubber dam was placed and the tooth structure was inspected for possible cracks. Since no cracks were detected, the postendodontic treatment disease was attributed to disinfection failure and remaining intracanal bacteria (Figure 8.5). Endodontic mishap repair procedure: the gutta-percha was removed with Gates Glidden burs and Hedstrom files (Figure 8.5).

8.3 ­Treatment pla

Figure 8.2  A lateral opening drilled in the coronal one-third of the crown.

Figure 8.3  Exposed cast post after lifting of the crown.

●●

●●

Canal preparation (or retreatment procedure): the canal was enlarged to 60/04 apical size with controlled memory files. Irrigation (solution and technique): the disinfection was achieved in two visits, with positive syringe irrigation of 5% NaOCl followed by negative pressure irrigation (EndoVacTM). The canal was bubble free flooded with NaOCl and a precurved stainless steel file was used to scout the lateral canal walls. The irrigant was activated with ultrasonics (3 × 20 seconds). Negative pressure was used to deliver the irrigant safely to the apical third and PUI was used to deliver the irrigant to the lateral extensions of the root canal system.

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8  Clinical Case 8

(a)

(b)

Figure 8.4  (a,b) Demonstrating the use of WAM X forceps for decementing the cast post from the tooth.

●●

●●

●●

Final irrigation protocol: the canal was flooded with 17% EDTA for 2  minutes followed by sterile water irrigation. The canals were dried with a suction capillary tip and paper points. Obturation (material and technique): obturation of the apical third was achieved with a continuous wave of condensation technique. Resin-based sealer was used in combination with gutta-percha as the core material. The canal was backfilled with injectable gutta-percha and post space was created with the System BTM plugger (Figure 8.6) and verified on a radiograph (Figure 8.7). Additional information: a new cast post and core were fabricated and a provisional crown restoration was placed.

8.4 ­Technical aspects Cast post removal techniques should respect the amount of the remaining tooth structure. The WAM X device approach might be used safely to remove challenging cases of cast posts. After cast post removal, it is imperative to assess the restorability of the remaining tooth structure before continuing the root canal retreatment procedures. The remaining tooth structure is inspected under high magnification for any possible cracks that might jeopardize the treatment outcome. If no cracks are detected, the initial treatment failure should be attributed to disinfection failure. Removing non-obturation materials and obturation materials, exposing the canal walls to the irrigants used and adopting sophisticated disinfection techniques seem to be the keys to achieving infection control compatible with tissue healing.

8.4 ­Technical aspect

Figure 8.5  Disinfection procedure being carried out and the removal of gutta-percha with GG drills and Hedstrom files.

Figure 8.6  Sectional obturation of the apical part is complete and the prepared post space can be seen.

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8  Clinical Case 8

Figure 8.7  Radiograph confirming the sectional obturation along with post space preparation.

8.5 ­Follow-up The 3-year follow-up clinical and radiographical evaluation revealed an asymptomatic tooth, periodontal probing within normal limits and healing of the lateral lesion visible in the twodimensional periapical radiograph (Figure 8.8).

8.6 ­Learning objectives ●●

●●

●●

●●

The root canal system of single canal teeth might present with complicated lateral extensions in which bacteria can spread and remain unaffected by treatment procedures. Anatomical intricacies need to be incorporated into the disinfection process by adopting sophisticated disinfection techniques. Patency maintenance, lateral wall scouting, negative pressure irrigation and ultrasonic activation of the irrrigants are some of the conventional procedures used to achieve infection control compatible with tissue healing. The WAM X device seems promising for the non-destructive removal of challenging cast post systems.

9/2013

9/2013

9/2015

Figure 8.8  Recall radiograph confirming healing of the lateral lesion following the root canal retreatment.

8.7  ­How can this endodontic

mishap be avoided

8.7 ­How can this endodontic mishap be avoided? Voids between the cast post and the apical gutta-percha plug might facilitate the growth of remaining bacterial species. These bacteria can gain access to the host defence mechanism through the lateral extensions of the root canal system and initiate lateral periodontitis. A good aseptic technique with rubber dam isolation during post fabrication and cementation is strongly advised to avoid the reinfection of a previously infected root canal system. Minimizing and/or eliminating the voids between the post and the apical gutta-percha and implementing an aseptic post placement technique might prevent post-treatment endodontic disease in cases with postretained restorations.

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9 Clinical Case 9 – Management of a case with endo-perio lesion following a previous root canal treatment Antonis Chaniotis

Introduction to the case: a combined endodontic-periodontal lesion associated with previously inadequate root canal treated teeth.

9.1 ­Patient information ●● ●● ●●

Age: 20 years old. Gender: Male. Medical history: non-contributory.

9.2 ­Tooth ●● ●● ●●

●●

●●

Identification: central mandibular incisors (Teeth 31–41). Dental history: central incisors are not stable and pus is draining through a sinus tract. Clinical examination findings: mandibular central incisors painful on percussion and palpation. Deep periodontal probing defects (12 mm probing depths mesially). Teeth #31 and #41 grade 3 mobility. Buccal draining sinus tract (Figure 9.1). Preoperative radiological assessment: radiographical examination revealed previously treated mandibular central incisors with complete interdental bone loss (Figure 9.2). Diagnosis (pulpal and periapical): pulpal diagnosis consistent with previously treated teeth. Periapical diagnosis – symptomatic periodontitis suggesting a true combined endo-periodontal lesion. The existence of a crack or vertical root fracture was suspected.

9.3 ­Treatment plan ●●

Preliminary procedures: both teeth were anaesthetized with buccal infiltration anaesthesia. The rubber dam was placed and stabilized in place. Composite restorations were removed with a carbide blunt bur without water irrigation and the gutta-percha was exposed. The coronal part of the previous gutta-percha obturation was removed with a no. 3 Gates Glidden bur. Chloroform

Clinical Atlas of Retreatment in Endodontics, First Edition. Edited by Viresh Chopra. © 2021 John Wiley & Sons Ltd. Published 2021 by John Wiley & Sons Ltd. Companion website: www.wiley.com/go/chopra/retreatment

9.3 ­Treatment pla

(a)

(b)

Figure 9.1  (a,b) Clinical pictures showing tracking of the sinus tract with the help of gutta-percha and measuring the probing depth in the affected teeth.

●●

was used as a solvent to soften the middle third gutta-percha remnants. Special care was taken to remove all the previously infected gutta-percha material and to expose the root canal walls to the disinfection procedure. Microscopic inspection of the access cavity and the inner canal walls revealed sound tooth structure without any visible crack lines. Treatment plan for management of the endodontic mishap: initial treatment failure was attributed to inadequate disinfection and possible missed infected anatomy. For this reason, the access cavity

Figure 9.2  Preoperative radiograph revealing previously treated mandibular central incisors with complete interdental bone loss.

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9  Clinical Case 9

●●

●●

●●

●●

●●

●●

was strategically extended lingually and special care was taken to remove all the gutta-percha remnants from the canal walls. For the removal of the gutta-percha remnants, a Hedstrom file was used mounted in an endo-holder and precurved with an endo-bender. No lingual missed canal was found. The cross-sectional shape of both canals was rather long and oval with an extended buccolingual dimension. Endodontic mishap repair procedure: special care was taken to drive the disinfection agents to the last apical millimeter of the oval canals and to the possible lateral extensions of the root canal system. For this reason, a negative pressure irrigation delivery technique was used supplemented with passive ultrasonic activation of the irrigants. Negative pressure safely drives the irrigants to the apical third whilst passive ultrasonic activation facilitates distribution of the irrigant to the lateral extensions of the root canal system. Canal preparation (or retreatment procedure): after removal of the previous obturation material, the canal was apically gauged with a 50/04 HyFlex® CM rotary file. Irrigation (solution and technique): the chloroform irrigation used to dissolve the gutta-percha was followed by alcohol irrigation to remove the chloroform remnants. Disinfection was achieved by using alternate 17% EDTA and 4.8% NaOCl with positive syringe irrigation. This alternate combination of irrigants is suggested to facilitate the debonding of well-attached gutta-percha remnants and expose the canal walls to the disinfection procedure. After enlarging the canals to 50/04, the microcannula of the EndoVacTM (negative pressure irrigation) was used to safely deliver the irrigant to the last apical third. The canal was bubble free filled with 4.8% NaOCl and the irrigant was activated with ultrasonics (3 × 20 seconds, IrrisafeTM tip). The canals were dried and filled with calcium hydroxide (UltraCalTM). A temporary restoration was placed. The calcium hydroxide was left for 2 weeks until symptoms were resolved and the buccal sinus tract was healed. The mobility of the teeth returned to within normal limits. Final irrigation protocol: the temporary restorations were removed and the calcium hydroxide was rinsed with sterile water. The canal was bubble free filled with 17% EDTA with the EndoVac system. A stainless steel hand file was precurved with an endo-bender and used to scout the lateral canal walls. The objective was to maintain patency of the entrance of any possible lateral extensions of the root canal system. The final rinse before obturation was done with 4.8% NaOCl followed by sterile water. The canals were dried with a suction capillary tip and paper points. Obturation (material and technique): obturation of the apical third was achieved with continuous wave of condensation technique. Resin-based sealer was used in combination with gutta-percha as the core obturating material. The canal was backfilled with injectable gutta-percha. After completion of the obturation procedures, a lateral portal of exit was visualized in the mesial apical third of Tooth #31 (Figure 9.3). This lateral extension of the root canal system might explain the pathway of bacterial ingress and justify the combined endodontic-periodontal defect. Additional information: both teeth were restored with direct composite restorations.

9.4 ­Technical aspects ●●

Initial treatment failure usually is attributed to intracanal bacterial biofilm infection. The bacterial biofilm is located between the canal walls and the obturation materials, in the untouched canal walls or inside the anatomical intricacies of the root canal system. In order for the disinfection retreatment procedures to be effective, the bacterial biofilm needs to be exposed. Complete removal of the previously infected obturation materials is a challenging procedure. Microscope magnification and specially designed instruments might facilitate the process. In the case

9.6 ­Learning objective

Figure 9.3  Periapical radiograph revealing obturation of the anterior teeth. A lateral portal of exit can be visualized in the mesial apical third of Tooth 31.

reported here, a Hedstrom hand file was used mounted in an endo-handle. The use of solvents can facilitate penetration of the files inside the gutta-percha mass of well-compacted root canal fillings. Alternate irrigation of 17% EDTA and 4.8% NaOCl can facilitate the debonding of firmly attached obturation materials.

9.5 ­Follow-up Follow-up clinical examination at 1 year revealed asymptomatic teeth without any signs of infection and normal mobility (Figure 9.4). Periodontal probing was within normal limits. Radiographical examination revealed complete healing and regeneration of the interdental bony defect (Figure 9.5).

9.6 ­Learning objectives ●●

●● ●●

The root canal system possesses anatomical intricacies in which bacteria can spread and remain unaffected by treatment procedures. It is a challenge to completely remove all the obturation materials from root canal systems. Microscopic magnification and miniaturized instruments can facilitate the process of removing infected obturation materials and expose the infected dentinal walls to the disinfection process.

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9  Clinical Case 9

(a)

(b)

Figure 9.4  (a,b) Clinical pictures showing healing of the buccal sinus tract as well as the decrease in the probing depth 1 year after the retreatment. Figure 9.5  Periapical radiograph showing healing of the interdental radiolucent lesion between Teeth 31 and 41 1 year after the retreatment procedure.

●●

●●

Negative pressure irrigation and passive ultrasonic activation of the irrigants can facilitate the delivery of irrigants to the last apical third and to the lateral extensions of the root canal system. Primary endodontic/secondary periodontal lesions possess the potential to heal completely whenever adequate disinfection level is achieved.

9.7  ­How can this endodontic

mishap be avoided

9.7 ­How can this endodontic mishap be avoided? The use of aseptic techniques during initial root canal treatment and thorough knowledge of root canal system anatomy help to prevent disinfection failures. Mechanical enlargement of the root canal system might block the lateral extensions to the disinfection procedures used. It is important to implement a working concept that can maintain the patency of the lateral extensions of the root canal system.

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10 Clinical Case 10 – Management of a failed root canal treatment with silver cone obturation and fractured instrument Antonis Chaniotis

Introduction to the case: case of failing silver cone initial treatment with apically located broken file below the curvature.

10.1 ­Patient information ●● ●● ●●

Age: 28 years old. Gender: Female. Medical history: non-contributory.

10.2 ­Tooth ●● ●●

●●

●●

●●

Identification: left second maxillary premolar (Tooth 25). Dental history: previously root canal treated maxillary premolar with silver cone obturation and composite resin build-up. Chief complaint: my tooth needs a new crown but I feel pain when I press it. Clinical examination findings: Tooth 25 painful to percussion and palpation. Periodontal probing within normal limits. Preoperative radiological assessment: the periapical radiograph revealed a previously treated premolar with an associated periapical lesion. Detailed examination revealed silver cone obturation of the canal system and an apically located file fragment (Figure 10.1). Diagnosis (pulpal and periapical): pulpal diagnosis was consistent with previously treated tooth. Periapical diagnosis was consistent with symptomatic apical periodontitis.

10.3 ­Treatment plan ●●

Preliminary procedures: the patient was anaesthetized with buccal infiltration anaesthesia. The rubber dam was placed and stabilized in place. The composite resin restoration was removed with diamond burs. The deepest layers of the composite resin in contact with the silver cone were removed with a dry working ultrasonic tip in order to avoid separation of the silver cone head.

Clinical Atlas of Retreatment in Endodontics, First Edition. Edited by Viresh Chopra. © 2021 John Wiley & Sons Ltd. Published 2021 by John Wiley & Sons Ltd. Companion website: www.wiley.com/go/chopra/retreatment

10.3 ­Treatment pla

Figure 10.1  Preoperative radiograph showing silver cone obturation and fractured instrument in the apical third of the canal. Periapical radiolucent changes are also evident.

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●●

●●

Treatment plan for management of the endodontic mishap: the silver cone was located in the buccal root canal and its head was exposed. Chloroform solvent was used with caution around the silver cone to soften the surrounding cement. The solvent was worked around the silver cone with an endodontic DG16 explorer until the silver cone became movable. A Hedstrom file was used along the side of the silver cone to engage and lift the silver cone outside the canal. After removal of the silver cone, the gutta-percha remnants were removed with retreatment rotary files and alternate use of EDTA and NaOCl irrigation. All the previous obturation materials were removed and radiographically verified (Figure 10.2). Endodontic mishap repair procedure: after removal of all gutta-percha remnants, the canals were filled with water and dried with paper points. Microscopic inspection of the palatal canal failed to reveal the coronal end of the broken fragment, suggesting a location below the curvature. Canal preparation (or retreatment procedure): in order to visualize the coronal end of a broken fragment located below the curvature, the canal walls need to modified. An ISO 25 ultrasonic K-file is mounted in an ultrasonic file holder and the tip of the ultrasonic file is bent in the preferred direction with an endo-bender instrument (Figure 10.3). Dedicated dentine removal is needed at the point of the inner curvature canal wall and the outer wall in the coronal part of the canal. The objective is to achieve straight-line visual access to the fragment. Dentine removal needs to be kept to a minimal level that will not jeopardize the integrity of the root itself. Once the fragment is visualized, a tiny space is obtained with the ultrasonic file at the point of the inner curve. A thin and long DG16 sharpened explorer is used to luxate the

Figure 10.2  Periapical radiograph showing removal of silver cone and cement to expose the fractured instrument.

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10  Clinical Case 10

Figure 10.3  Precurving the endodontic file with an endo-bender.

●●

●●

fragment toward the direction of the inner curve. Once the fragment is loosened by the endodontic explorer, the ET 25 pointed tip (Satelec®) is used on a higher energy setting (Figure 10.4). The objective is to make the mobile fragment rotate (dancing). This can be done with interrupted ultrasonic activations of the ET 25 tip in a wet environment. The canal is filled with 17% EDTA and the ET 25 tip is inserted toward the space created in the inner curve. Short activations of the ultrasonic tip deliver enough energy to the fragment to induce rotation. Replenishment of the 17% EDTA is mandatory to keep the environment moist and cool the fragment. Usually a fragment like the one reported here pops out of the canal in less than 10 seconds after the use of the ET 25 tip. Fragments longer than 4.5 mm might need a gripping device to be removed. Fragments smaller than 4.5 mm can generally be removed with ultrasonic vibration. Irrigation (solution and technique): after fragment removal, the canal is often ledged. Precurved hand instruments or precurved controlled memory rotary files can be used to negotiate the canal below the ledge. In the case reported here, precurved flare files (MANI) were used. Irrigation was achieved by using 4.8% NaOCl solution followed by 2 minutes of 17% EDTA canal flooding. A precurved ISO 12 D-finder hand file was used to scout the lateral canal walls. Final irrigation protocol: the final rinse was done with sterile water and the canals were dried with capillary suction tip and paper points.

ET 25

Figure 10.4  ET 25 ultrasonic tips used to loosen and remove the fractured instrument from the apical third of the canal.

10.6 ­Learning objective

Figure 10.5  Periapical radiograph showing obturation and post space preparation in order to receive fiber post.

●●

●●

Obturation (material and technique): obturation of the apical third was achieved with continuous wave of condensation technique. Resin-based sealer was used in combination with gutta-percha. The canal was backfilled with injectable gutta-percha and post space was created in the palatal canal with the System BTM plugger. The obturation and post space preparation were verified on the radiograph (Figure 10.5). Additional information: the tooth was restored with a fiber post and composite build-up. A crown was placed.

10.4 ­Technical aspects ●● ●● ●● ●● ●● ●●

The use of magnification and illumination is mandatory for cases of broken file removal. The use of solvents might facilitate the removal of challenging silver cones. A sharp and long DG 16 explorer is mandatory in cases of broken metals inside root canals. Removal of dentine must be kept to a minimum. Ultrasonic activation is always interrupted in order not to overheat the fragment. Practice on extracted teeth is mandatory before implementing broken instrument removal techniques in the clinic.

10.5 ­Follow-up The 2-year follow-up clinical and radiographical examination revealed uneventful healing with no signs or symptoms (Figure  10.6). Healing was verified by a pre-existing CBCT examination (Figure 10.7).

10.6 ­Learning objectives ●●

Removal of silver cones from the canal ranges from very easy to extremely challenging. Wellcemented silver cones need solvent to become dislodged. Preserving the extruded head of the cone is highly recommended in order to be able to retrieve it easily once it becomes movable. Direct ultrasonic vibration is not indicated with silver cones because of the risk of overheating

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Figure 10.6  Periapical radiograph showing healing of the periapical lesion 2 years after the root canal retreatment.

Figure 10.7  CBCT showing healing of the periapical lesion 2 years after the root canal retreatment.

●●

and secondary breakage. In certain cases of resistant silver cones, direct ultrasonic vibration can be used to evaporate the visible parts of the cone. Removal of broken files is always challenging. In particular, files that separate below the curvature can be very difficult or impossible to remove. Whenever the broken file is visible or can be rendered visible, the removal success rate is expected to be higher if ultrasonics are used.

10.7 ­How can this endodontic mishap be avoided? A deep understanding of root canal system anatomy is mandatory before initiating any attempt at endodontic treatment. Thorough examination of all preoperative radiographs might reveal most common curvatures. Different angulations of preoperative radiographs or preoperative CBCT examination might also reveal proximal unseen curvatures. Curved canal management is challenging and the operator needs to be alert. The single use of rotary and hand instruments is believed to be the best way to prevent instrument separation in complicated canal systems. If instruments are to be cleaned, sterilized and reused, a technique that will minimize the torsional stresses of the activated file might be beneficial and prevent the file from breaking. Frequent cleaning of file flutes and frequent checking for flute distortions is also suggested.

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11 Clinical Case 11 – Management of a failed root canal treated maxillary molar with selective root treatment Gergely Benyőcs

11.1  ­Introduction to the concept of selective root treatment ‘Primum non nocere’ – first do no harm – should be a must during our endodontic treatments. We often just follow a routine, applying the same protocoreferencel to every case. In retreatments, for example, we usually get used to following the ‘all or none’ approach – removing all restorative and obturation materials from every root canal, regardless of the presence or absence of periapical pathosis [1]. In the author’s opinion, this approach is not always justified. Regarding multirooted teeth, we could consider that retreatment should be limited to a single root or roots clearly showing periapical pathosis while leaving the root(s) with no visible or perceived pathosis untouched  [2]. The surgical option is usually chosen over non-surgical retreatments [3]. One reason to adopt this concept is to avoid the risks of non-surgical retreatment such as iatrogenic errors, weakening of the tooth, creating heat, creating perforation, fractures during post removal, etc. When considering this treatment option, proper examination should be undertaken: ●● ●● ●● ●●

to achieve proper diagnosis followed by meticulous treatment planning to ascertain the quality of the coronal seal to rule out secondary caries to evaluate selectively the signs of inflammation around apices.

Secondary caries can be detected with the help of bitewing radiographs. However, for coronal restorations, this can be challenging. In order to decide whether to preserve or remove the restoration, use of high magnification, probing and examining the periodontal conditions are mandatory.

11.2  ­Decision making Non-surgical retreatment should be the first option. Endodontic surgery offers more favourable initial success but non-surgical retreatment offers a better long-term outcome [4]. However, considering the costs and benefits of different treatment options, patient consent should be taken after proper guidance by the operator. Clinical Atlas of Retreatment in Endodontics, First Edition. Edited by Viresh Chopra. © 2021 John Wiley & Sons Ltd. Published 2021 by John Wiley & Sons Ltd. Companion website: www.wiley.com/go/chopra/retreatment

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The various treatment options after careful examination include the following. ●●

●●

●●

●●

●●

No treatment/observation: the patient always has the right not to be treated. Observation could be the option for a patient without any complaints with or without signs of periapical pathosis. With signs of pathosis, one should determine the stage of the inflammation – whether it is healing, stagnating or progressing. For that purpose, previous x-rays and/or cone beam computed tomography (CBCT) should be compared with current ones. Conventional non-surgical retreatment: this is the only choice when coronal leakage has occurred and is the automatic treatment of choice for missed canals and irrigation failures [5]. Selective root retreatment: option for evident signs of periapical findings on delicate root/root canals. Intact around the other ones. Surgical treatment – apicoectomy: after acceptable endodontic treatment, without changing or progression of periapical findings, in case of tight coronal structures, apical damage, etc. Good periodontal conditions are mandatory. Extraction: sometimes patients expect too much or want 100% success and they may be looking for a warranty. According to our best knowledge, we cannot meet all those expectations. In that situation, extraction could be an option [1].

11.3  ­Laying down the treatment plan In the author’s opinion, use of the smallest field of view (FOV) CBCT and high magnification is crucial to plan and work in this conservative way. This allows accurate evaluation of the periapical status of individual roots and secure navigation in confined spaces. With proper examination and bitewing radiographs, secondary caries and leakage should be ruled out. CBCT can be used for measurements to ascertain the entry point of the access, the depth of drilling and to estimate the angulation of drilling. The latter is quite critical; its accuracy depends enormously on the operator’s experience. With the help of guided endodontics, access preparation can be carried out in a more accurate way (see Case 12).

11.4  ­Steps of selective retreatment Magnification is recommended for correct visual control. In order to have full control while drilling, use of long shank small-headed burs is advisable. Also, in order to ensure free entry to the root canal orifices and to create correct orifice directed access preparation [6], access should be modified and individualized, taking care of the pericervical dentine  [7]. Pericervical dentine means roughly 4 mm dental structures above and below the crestal bone. Since the mechanical characteristic of the dentine in this area is still not replaceable with any material or technique, preserving the ferrule seems crucial for long-term survival of the tooth [8]. To achieve this goal: ●● ●● ●●

restorations should be removed before tooth structures (do not save the plastic) enamel should be removed before dentine access should be modified rather occlusally than cervically.

After creating ideal access and entering the orifices, conventional root canal treatment on the selected root can be carried out.

11.5  ­Introduction to the clinical cas

11.5  ­Introduction to the clinical case Selective root retreatment on MB root of Tooth 16. Demonstration of the role of the operating microscope and step-by-step presentation of the use of CBCT for navigation.

11.5.1  Patient information ●● ●● ●●

Age: 35 years old. Gender: male. Medical history: non-contributory.

11.5.2  Tooth ●● ●● ●●

●●

Identification: right maxillary posterior region. Dental history: hief complaint: pain on biting in upper right maxillary posterior region. Clinical examination findings: pain on percussion and palpation. Severely tender to percussion irt Tooth 16 (Figure  11.1a). The two-dimensional periapical radiograph revealed a previously root canal treated Tooth 16 with an obturation of the root canal system remaining short of the radiographic apex in the mesial canal. Periapical radiolucency could also be detected (Figure 11.1b). CBCT examination revealed an apical radiolucency as well as in relation to the mesiobuccal root of the tooth (Figure 11.2). Diagnosis (pulpal and periapical): symptomatic apical periodontitis.

11.5.3  Treatment plan Since periapical pathosis was found only around the MB root and the old restoration seemed intact, two-visit CBCT-guided selective retreatment was planned. ●●

Preliminary procedures –– Measurements on horizontal and sagittal view of the CBCT (Figure  11.3) were approximated on the occlusal surface (Figure  11.4) and drilling depth was measured on the bur (Figure 11.5).

(a)

(b)

Figure 11.1  (a) Clinical picture showing Tooth 16. (b) Periapical radiograph showing previously root canal treated Tooth 16. The obturation seems short of the radiographic apex in the mesial canals.

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Figure 11.2  CBCT imaging reveals presence of periapical radiolucency along the mesiobuccal root of Tooth 16.

●●

●●

–– Buccal infiltration anaesthesia was administered. To be sure about the orientation, conservative access preparation was carried under rubber dam isolation. Obturated MB1 became visible (Figure 11.6). Treatment plan for management of the endodontic mishap –– Before removing the older gutta-percha from MB 1, the conservative guided access cavity was modified to locate the MB 2 canal. Canal patency was checked with a 10 K file and verified on the radiograph (Figure 11.7). Once the working length was determined in the MB 2 canal, the gutta-percha in the canal was removed with rotary retreatment files (D1, D2 and D3). No solvent was used as it was judged unnecessary. –– The canal was cleaned and shaped with ProTaper® Universal S1, ProTaper Next X1 and HyFlex® 04/20 used up to the working length. The final apical size was reached with NiTi hand files (02/35 MB1, 02/25 MB2) (Figure  11.8a). Once the final cleaning and shaping were achieved, the MB1 and MB2 canals were clearly visible under magnification (Figure 11.8b). –– Disinfection was achieved with positive syringe irrigation of 5% NaOCl. The canal was flooded with 17% EDTA for 5 minutes and then rinsed with 5% NaOCl. Alternate use of EDTA and NaOCl during retreatment can facilitate the debonding of well-attached remaining obturation materials. Endodontic mishap repair procedure: in this case, the endodontic mishap was the missed MB2 canal as well as the short obturation in the MB 1 canal. The procedure to correct the mishap is to locate the missed MB2 canal and retreat MB1 and obturate both canals up to correct working length.

11.5  ­Introduction to the clinical cas

(a)

(b)

Figure 11.3  (a) CBCT used for measurements on the occlusal surface. (b) Measurements showing distance of root canal orifices from occlusal surface. ●● ●● ●●

Irrigation (solution and technique): 5% NaOCl; passive ultrasonic irrigation (3 × 20 seconds). Final irrigation protocol: 17% EDTA (syringe irrigation) for 3 minutes. Obturation (materials and technique): master cone GPs were verified on the radiograph (Figure 11.9). Tricalcium silicate-based sealer was used along with gutta-percha as the core obturating material. The technique used was warm vertical compaction and an immediate postoperative radiograph was taken to verify the obturation (Figure 11.9b).

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Figure 11.4  Based on CBCT measurements on the occlusal surface, the estimated position of the access cavity is traced in vivo.

Figure 11.5  Drilling depth marked with a stopper on the bur. Rubber dam removed to be sure about the orientation.

11.5.4  Technical aspects The internal anatomy of human teeth is complicated, and there is a high incidence of presence of MB2 canals in maxillary first molars. Failure to locate the MB2 canal and obturate up to the working length can easily lead to failure of root canal treatment. The cleaning and shaping procedure during retreatment should address both the main and the extra canals.

11.5  ­Introduction to the clinical cas

Figure 11.6  Guided access prepared without rubber dam. Previously obturated MB1 located under the microscope.

Figure 11.7  Missed MB2 discovered. 10 K file used to check canal patency. Length was controlled with an electronic apex locator and verified on periapical radiograph x-ray.

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(a)

(b)

Figure 11.8  (a) MB1 and MB2 shaped and cleaned with rotary endodontic files under conservative access cavity preparation. (b) MB1 and MB2 clearly visible under magnification after the final cleaning and shaping procedure.

(a)

(b)

Figure 11.9  (a) Verification of master GP on the radiograph. (b) Immediate postoperative radiograph showing obturation of the MB1 and MB2 canals up to the working length.

11.7  ­Learning objective

Figure 11.10  Follow-up after 1 year showing complete healing of the periradicular area.

11.5.5  Follow-up One-year follow-up revealed an asymptomatic tooth and uneventful healing (Figure 11.10).

11.6  ­Conclusion With the help of the conservative approach, using magnification, CBCT, and ultra-flexible heattreated instruments, selective root retreatment is a sensible option. The main goal should always be to ensure a functional root canal treated tooth for a long period of time. That is why an individualized treatment plan and protocol is necessary, in order to be less invasive and to save as much sound dental structure as possible. It is important to emphasize that being less invasive should not mean being clinically less successful [9]. All the root canals should be detected, cleaned and well obturated to our best knowledge. However, technological developments have made it possible to save more sound dental structures, ‘banking’ them for further interventions. We hope to meet our patients’ expectations, and to provide functional, good-looking, complaint-free root canal treated teeth, hopefully for a lifetime.

11.7  ­Learning objectives The reader should understand: ●● ●● ●● ●● ●● ●●

●●

that with the help of magnification, less invasive access preparation is achievable the complexity of the root canal system the limitations of two-dimensional imaging the importance of using selective guided tools for retreatment in endodontics the significance of use of CBCT in failed root canal cases that using CBCT for guidance, the entry point of access and the depth of drilling can be approximated and use stepwise guided tools for retreatment procedures.

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11.8  ­How can this endodontic mishap be avoided? Clinicians need to understand that they are dealing with a complicated canal system with presence of lateral canals and apical deltas. Inadequate cleaning, shaping and irrigation of the root canal system might leave such areas uncleaned, which will allow bacteria to spread and remain unaffected by treatment procedures. It is a challenge for the specialty to develop techniques that will enable and facilitate location of extra canals with use of the correct instruments. Obturations should be carried out up to the full working length and the endodontic access cavity should be carefully searched for the presence of any extra canals.

­References 1 Nudera, W.J. (2015). Selective root retreatment: a conservative alternative. www.dentaltown.com/ Dentaltown/OnlineCE.aspx?action=DETAILS&cid=589 2 Nudera WJ. Selective root retreatment: a novel approach. J Endod 2015; 41: 1382. 3 Benyőcs G, Kinariwala N. Static guided non-surgical approach for posterior teeth. In: Kinariwala N, Samaranayake L (eds) Guided Endodontics. Springer, New York, 2021, pp. 135–49. 4 Torabinejad M, Corr R, Handysides R, Shabahang S. Outcomes of nonsurgical retreatment and endodontic surgery: a systematic review. J Endod 2009; 35: 930–7. 5 Buchanan L. Endodontic treatment planning in the fourth dimension. Dent Today 2010; 9. 6 Schwartz R, Canakapalli V. Best Practice in Endodontics: A Desk Reference. Quintessence Publishing, Hanover Park, IL, 2015. 7 Clark D, Khademi J. Modern molar endodontic access and directed dentine conservation. Dent Clin North Am 2010; 54: 249–70. 8 Naumann M, Schmitter M, Frankenberger R, Krastl G. ‘Ferrule comes first. Post is second!’ Fake news and alternative facts? A sytematic review. J Endod 44:2 212–19, 2018. 9 Nasseh AA, Trope M, West J. Minimally invasive endodontics: finding the right balance between ‘too much’ and ‘not enough’. Compendium37:1, 2016.

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12 Clinical Case 12 – Guided endodontics and its application for non-surgical retreatments: Retreatment of a maxillary anterior tooth using static guidance Gergely Benyőcs

12.1  ­Introduction to guided endodontics The modern endodontic approach tends to be more conservative, with less invasive procedures and techniques. This philosophy is increasingly becoming a part of both graduate and postgraduate education. This is in accordance with the objectives of endodontic treatment that not only prevents and/or eliminates apical periodontitis, but also preserves sound dental structures for the long term and provides lifetime retention of natural teeth. This is all the more important since the lifespan of the population is increasing and teeth need to function for more than 80 years. Restorations, composite fillings and calcifications create challenges, and sometimes make it impossible to carry out endodontic treatments. This could lead to excessive tooth structure loss and sometimes fatal failures with freehand access preparation (Figures 12.1 and 12.2).

12.2 ­Pulp canal calcification Pulp canal calcification (PCC) occurs as a sequela of dental trauma or in elderly patients [2, 3]. PCC usually develops because of the formation of secondary and tertiary dentine [4]. Orthodontic treatment may also trigger or accelerate the apposition of secondary dentine [5, 6]. Although PCC is considered a sign of pulp vitality and that root canal treatment should not be undertaken unless there is clinical and radiographic evidence of pulp necrosis, it remains that in the long term, necrosis usually affects up to 33% of teeth with PCC [7]. Access and shaping become very challenging in these cases and a high failure rate ensues, especially in narrower teeth. The American Association of Endodontists rates the treatment of teeth with PCC as having a “high difficulty” level [7]. Even with magnification, the search for the elusive root canal may lead to excessive dentine removal that will in turn jeopardize biomechanics and reduce the long-term prognosis [8]. The advent of digital dentistry, specifically 3D scanning and printing, allows for a new approach to teeth affected by PCC using a printed guide that will serve as a guide to the bur [9, 10].

Clinical Atlas of Retreatment in Endodontics, First Edition. Edited by Viresh Chopra. © 2021 John Wiley & Sons Ltd. Published 2021 by John Wiley & Sons Ltd. Companion website: www.wiley.com/go/chopra/retreatment

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Figure 12.1  Various endodontic mishaps that can occur with freehand access preparation. Pre-op

Cone-control

Post-op, 06.2016

04.2018

Figure 12.2  How calcification can create a challenge during endodontic treatment. In such complex situations, guided endodontics could be a useful approach for general dentists, and even for endodontists [1].

12.3  ­Improving the accuracy of access preparation There are many ways to avoid failures. The main goals are to improve mental guidance, maintain accurate access preparation and carry out less invasive and safer endodontic treatments (Figure 12.3). First, proper examination is mandatory. While touching the tooth surfaces and moving the periodontal probe around the cementoenamel junction, one can get an impression of the anatomy of the tooth to be treated, observing convex and concave surfaces, then creating a 3D mental reconstruction of the situation. To improve accuracy during access preparation, use of good-quality x-rays taken from different angulations and cone beam computed tomography (CBCT) is advisable as the first option. With the help of these tools, the entry point of the access can be measured and approximated on the occlusal surface. The depth of drilling can be extrapolated on the bur (see Clinical case 11, Figure  11.5). However, the angulation of drilling can be challenging and its accuracy greatly depends on the operator’s experience. To overcome the latter, tools for static and dynamic guided endodontics are available. At the entry point of access, the depth and angulation of drilling are precisely implemented by the tool. Less invasive and more accurate access preparation becomes possible, regardless of the operator’s experience.

12.4  ­Static guidanc

USE YOUR BRAIN

PARTIALLY GUIDED

FULLY GUIDED

3D PRINTED TEMPLATE GUIDED ENDODONTIC TREATMENTS

X-RAY DRIVEN

3D PRINTED TEMPLATE

ENDODONTIC

GUIDED SURGICAL

TREATMENTS

CBCT DRIVEN

GUIDED

ENDODONTIC TREATMENTS

ENDODONTICS

ENDODONTIC

NAVIGATION WITH

TREATMENTS

3D PRINTED TEETH

COMPUTER AIDED 3D IMAGING

DYNAMICALLY GUIDED

SOFTWARES

ENDODONTICS

Figure 12.3  Different ways of improving the accuracy of endodontic access preparations and various possibilities to improve mental reconstruction of the case to be treated.

Figure 12.4  The steps of working with a 3D printed tooth replica.

In a complex situation, navigation with 3D printed teeth could also be an option [11]. With this process, the steps of the endodontic procedure can be planned and modelled on replicas, before carrying out any invasive intervention (Figure 12.4).

12.4  ­Static guidance In recent years, research has supported the utility of static guidance, mostly on calcified incisors [9, 12]. The American Association of Endodontists case assessment criteria place these cases into the high difficulty category (www.aae.org/specialty/clinical-resources/treatment-planning/ case-assessment-tools/) whereas, for example, in lower incisors with no or only partially visible root canal, the failure rate was 71% during root canal treatment [13]. The methodology for creating a static guide is the same as that used for guided implant placement in the last decade. The accuracy of guided endodontics seems acceptable. It allows accurate access cavity preparation up to the apical third of the root utilizing printed templates for guidance [10].

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Guided implantology vs. guided endodontics

Static guidance

Entry point (MD)

Apex (MD)

Angular deviation

Implantology

1.12 (max.4.5)

1.39 mm (max7.1)

3.89° (max. 21.16)

Endodontics

0.21 mm (max 0.75)

0.38 (max.1.59)

1.81° (max .5.6)

Computer Technology Application in Surgical Implant Dentistry: A Systematic Review Ali Tahmaseb, DDS/PHD/Daniel Wismeijer, DDS/PhD/Wim Coucke, MStat, Phd/Wiebe Derksen, DDS. The International Journal of Oral and Maxillofacial Implants, 2014;(suppl):24–52

Guided endodontics: accuracy of a novel method for guided access cavity preparation and root canal location. Zehnder MS1, Connert T1, Weiger R1, Krastl G2, Kühl S3. Int Endod J. 2016 Oct;49(10):966–72. doi: 10.1111/iej. 12544. Epub 2015 Oct 3.

Figure 12.5  Comparison of the accuracy of guided implant placement with guided endodontic treatment.

Comparing the accuracy of guided implant placement to guided endodontic treatment, significant differences exist (Figure  12.5). The reason for this is that for implant placement, different types of guide supports and more drills are used. Sometimes the implant is placed freehand [6]. However, with endodontic treatments, tooth-supported guides are used with one main drill for removing dentine during access preparation [9]. Guided endodontic procedures are promising techniques offering a highly predictable outcome and lower risk of iatrogenic damage [10]. Minimally invasive treatment can be performed and chairside time can be reduced. However, this should be interpreted with care since it is based on limited and low-quality evidence from case reports, observational studies, in vitro and ex vivo studies. Larger population studies with longer follow-up periods are required, as well as standardized experimental studies with similar sample size, aims and standardized measuring methods [14].

12.4.1  Advantages ●● ●● ●● ●● ●●

Easily accessible, price-conscious solution. Ideal for PCC cases. Application for premolars and molars with caution. Supported by evidence [14]. Accuracy is independent of operator experience.

12.4.2  Disadvantages ●● ●● ●● ●● ●●

Restorations could affect the accuracy of planning and drilling. One guide is not enough for treating multirooted teeth. Given interocclusal space is required (sum of the highs of the guide, sleeve and drill). Not suitable for high-speed burs. Not applicable for acute situations.

12.5  ­Approach to plannin ●● ●● ●●

Increased costs. Minor changes are not allowed. It can be used only in a straight line. Target points beyond curvatures are not reachable.

12.4.3  Challenges with static guidance The first challenge of using a static drill guide for conventional access is the common lack of interocclusal distance to accommodate the additional 10 mm of drill or bur length required by the guide ring position over the tooth (Figure 12.6). The second difficulty experienced when using static drill guides is that no guide rings exist that work with the 150 000 rpm that high-speed handpiece burs spin at when cutting through enamel, ceramics and cast restorations. Third, endodontics is a less elective procedure than implant surgery. Implant surgeons and their patients can easily wait to receive printed or milled drill guides before scheduling the procedure. Root canal disease commonly presents in such an acute form that nobody, patient or doctor, wants to wait for a printed or milled guide. Fourth, drill guides have 4–6 mm guide rings for each drill path, making it necessary to have a drill guide for each canal and thus creating greater expense in upper molars with four canals. Finally, static drill guides do not allow the minor but important changes in treatment plan that are often necessary during surgery [15].

12.5  ­Approach to planning Orifice projected access preparation is suggested in which the root canal orifices are projected on the occlusal surface (Figure 12.7). On one hand, the access is individualized to create free space for shaping and cleaning. On the other hand, preserving the pericervical dentine becomes possible [17] in a reasonable way (Figure 12.8). While working with the guide, it is advisable to remove: ●● ●● ●●

restorative material and caries before sound tooth structures enamel before dentine occlusal tooth structures before cervical dentine [18].

Figure 12.6  Common lack of interocclusal distance to accommodate the additional 10 mm of drill or bur length required by the guide ring position over the tooth. Source: Benyőcs and Kinariwala [16].

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12  Clinical Case 12

Figure 12.7  Demonstrating orifice directed access preparation.

Figure 12.8  Demonstrating the marked pericervical dentine that can be preserved in a reasonable way.

12.5  ­Approach to plannin

Figure 12.9  Different types of long shank small-headed burs recommended to be used for full visual control and greater conservation.

To achieve full visual control and be more cautious, long shank small-headed burs are recommended (Figure 12.9).

12.5.1  Steps for planning and printing Steps for planning are demonstrated in pictures from step A to step D. Preoperative CBCT DICOM files

Surface scan

DICOM and STL files STL files

uploaded to planning software

Step A Demonstrating the steps from recording of CBCT to transfer into the planning software.

First, the smallest field of view (FOV) CBCT is taken if possible and reasonable. The quadrant should be scanned (intraoral scan, impression or cast scan). DICOM files from CBCT and STL files from scanning are extracted and uploaded into the planning software. Theoretically, the same products could be used for planning static endoguides as for planning guided implant placement. After segmentation and alignment of the information (DICOM and STL), proper control of the superimposition is a critical step. This is done by scrolling through the three dimensions and following the line of the scan information, compared to CBCT reconstruction (see green line on the picture for Step B). Then the virtual bur and sleeve are placed and template is designed and finalized (Step C). After STL export, 3D printing is carried out (Step D).

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12  Clinical Case 12 Segmentation and alignment.

Step B Demonstrating segmentation and alignment of the information. Virtual ‘bur’ is placed to definite position

Virtual sleeve inserted, template designed STL files export

Step C Placement of virtual bur and sleeve. Producing the template in a 3D printer

Step D 3D printing in progress.

3d printed template for static guidance

12.7  ­Introduction to the clinical cas

According to the literature, 3D printing is accurate for endodontic use. Recent applications of 3D printing in the endodontic literature point to a possible paradigm shift in the way that challenging surgical and non-surgical endodontic treatments are accomplished [19]. Static guides are used for non-surgical primary endodontic treatments and retreatments and also for guided microsurgical endodontic treatments. It appears to be a viable technique which allows for predefined osteotomies and root resections [20].

12.6  ­Burs used for static guided endodontics Pilot burs for implant placement (1 and 1.2 mm diameter) are acceptable for this purpose, with individually fabricated metal sleeves (CNC). However, a special bur with sleeve is available on the market with 1 mm diameter (StecoGuide, https://steco.de/wp-content/uploads/2018/05/Orderform-GuidedEndo-05_18.pdf).

12.7  ­Introduction to the clinical case Single visit non-surgical retreatment on tooth 11, using 3D printed template with metal sleeve.

12.7.1  Patient information ●● ●● ●●

Age: 27 years old. Gender: male. Medical history: non-contributory.

12.7.2  Tooth ●● ●● ●●

●●

●●

Identification: right maxillary anterior region. Dental history: chief complaint: diffuse pain on buccal side of the right upper incisor. Clinical examination findings: periodontal probing depth was within normal limits, tooth was slightly movable. Palpation was positive rather buccally than palatally. Preoperative radiological assessment: the two-dimensional periapical radiograph revealed a previously root canal treated Tooth 11 with suspected fiber post luted almost up to the complete working length. Periapical radiolucency could be detected (Figure 12.10). Diagnosis (pulpal and periapical): symptomatic apical periodontitis.

12.7.3  Treatment plan To be clear about cost and benefits, different treatment options were discussed. ●● ●●

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No treatment: with the existing complaints, observation was not an option. Conventional non-surgical retreatment: this was considered, but there was difficulty reaching the apex through the restoration and the long glass-fiber post. Surgical treatment (apicoectomy): without retreatment could be favorable, but the patient was really anxious about it. In the author’s opinion, it would have been the ideal choice and less risky in this situation. Extraction: since the patient wanted to save the tooth, extraction was rejected.

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Figure 12.10  Periapical radiograph showing inadequate obturation in Tooth 11. Suspected fiber post cemented almost up to the full working length. Associated periapical radiolucency can also be seen.

An informed decision was made by the patient to go for conventional non-surgical retreatment, using static guidance to avoid complications. ●●

Preliminary procedures –– Steps for planning and printing: this was carried out via the approach mentioned above (see Figures 12.3–12.8). Since orifice projection would have been on the incisal edge, it was planned a bit palatally, resulting in removing the post partially along the working length. –– Preparation of the template and the guide to gain access to the root canal was done in a systematic order (Figures 12.11–12.20).

Figure 12.11  DICOM files from CBCT and STL files from scanning were extracted and uploaded into the planning software. Source: Courtesy of Dr Bertold Molnár.

12.7  ­Introduction to the clinical cas

●●

–– Once access was gained (Figure 12.21), working length was taken with the help of an electronic apex locator (Figure 12.22). –– Irrigation was carried out with 5.25% NaOCl, activated with a sonic device and manual dynamic activation. 17% EDTA was used, with saline water in between irrigation and also for the final rinse. Negative pressure technique was used throughout the retreatment procedure (Figure 12.23). Endodontic mishap repair procedure: in this case, the endodontic mishap was inadequate cleaning and shaping of the canal with faulty fiber post placement. It was corrected by regaining entry into the canal, performing thorough cleaning and shaping with copious irrigation.

Figure 12.12  Searching and marking of identical points. Source: Courtesy of Dr Bertold Molnár.

Figure 12.13  After segmentation and alignment of the information (DICOM and STL), proper controlling of the superimposition is a critical and necessary step. It was done by scrolling through the three dimensions (green line). Source: Courtesy of Dr Bertold Molnár.

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Figure 12.14  Placement of virtual burs and sleeve for final template designing. Source: Courtesy of Dr Bertold Molnár.

●●

●●

Obturation (materials and technique): master cone gutta-perchas were verified on the radiograph. Tricalcium silicate-based sealer was used along with gutta-percha as the core obturating material (Figure 12.24). After the obturation glass fiber post was cemented (Figure 12.25), verified on radiograph (see Figure 12.27d) and core build-up done with resin composite (Figure 12.26).

12.7.4  Technical aspects One of the most important steps in root canal treatment is cleaning and shaping with proper disinfection of the root canal system. Often, clinicians are in a hurry to finish the treatment and sometimes take shortcuts in irrigation steps. Inadequate disinfection might lead to residual

12.7  ­Introduction to the clinical cas

Figure 12.15  Placement of virtual bur a bit palatally since orifice projection would have been on the incisal edge.

Figure 12.16  The placement and stabilization of the guide in vivo.

bacteria, which can cause failure of root canal treatment in later stages, as seen in this case. Also, proper post space preparation and maintenance of proper post length are crucial for the success of root canal treatment.

12.7.5  Follow-up Six-month follow-up revealed an asymptomatic tooth and uneventful healing (Figure 12.27).

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Figure 12.17  Marking of the access entry point with a narrow bur on the restoration. The bur was used through the guide in order to maintain the correct angulation.

Figure 12.18  Once the marking was done, the hole was drilled freehand.

Figure 12.19  After replacing the guide, the stability of the guide bur was checked. It fitted passively in the hole created (buccal view).

12.7  ­Introduction to the clinical cas

Figure 12.20  After replacing the guide, the stability of the guide bur was checked. It fitted passively in the hole created (palatal view).

Figure 12.21  Access created with the guide bur, used with the sleeve. Root canal was detected.

Figure 12.22  Estimation of working length with an electronic apex locator.

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Figure 12.23  Negative pressure irrigation performed throughout the procedure.

Figure 12.24  Obturation done with tricalcium silicate sealer and gutta-percha as a core material.

Figure 12.25  Reinforcement with glass fiber post.

12.9  ­How can this endodontic mishap be avoided

Figure 12.26  Core build-up with resin composite.

(a)

(b)

(c)

(d)

(e)

(f)

Figure 12.27  (a–f) Periapical radiographs showing verification of the steps carried out for the retreatment of Tooth 11. The 6-month follow up radiograph (d) shows adequate healing of the periapical lesion.

12.8  ­Learning objectives The reader should be able to understand: ●● ●● ●● ●● ●●

●●

that with the help of magnification, less invasive access preparation is achievable the importance of using a subject guide to gain access the significance of a 3D printing guide the importance of using a selective guided tool for retreatment in endodontics that using CBCT for guidance, the entry point of access and the depth of drilling can be approximated and use a stepwise guided tool for retreatment procedures.

12.9  ­How can this endodontic mishap be avoided? Clinicians need to understand that they are dealing with a complicated canal system with presence of lateral canals and apical deltas. Inadequate cleaning, shaping and irrigation of the root canal system might leave such areas uncleaned which will allow bacteria to spread and remain unaffected by treatment procedures. Adequate cleaning and irrigation should be carried out as per protocol with obturations carried out up to the full working length.

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12.10  ­FAQs for guided endodontics 1) How to determine if the interocclusal space will allow use of the guide It is advisable to create a silicon block from impression material, with dimensions similar to the planned guide. The steps of the treatment can be attempted, trying in also short and long drills. 2) What to do if using the guide through restorations Since high-speed burs are not ideal for guided drilling, restorations and enamel should drilled by freehand preparations. The starting point should be marked through the sleeve, using a pen or bur whose diameter is smaller than the inner diameter of the sleeve. 3) How to ensure cooling while drilling through the guide With enough interocclusal space, an inspection window can be planned. With the help of that, external cooling is secured by the assistant. Intermittent stop by 1–2 mm is advisable. 4) How the direction of the drilling is controlled, while working deep, for example 20 mm and the height of the sleeve is only 5–7 mm It is advisable to start with the short guide drill. After reaching the dentine, the path drilled with that will act as a long sleeve. Guiding with the long guide drill should be done in a planned direction and not without that. 5) What to do if the root canal is not visible on CBCT scan Sometimes the diameter of calcified root canals is smaller than the best available resolution of the CBCT. That is why we suggest planning in the middle of the root, to the apex if possible. By intermittent stops, one can search for the root canals. Usually they are scouted before reaching the planned target point. 6) How to stabilize the guide during preparation It is suggested to stabilize with a finger on both sides of the guide. This should be considered while planning, to extend it properly on neighboring teeth. 7) How to deal with an already accessed tooth It is advisable to create a plateau at the bottom of the primary access. Ledges could misguide the bur. Modify the access to achieve free entry for the bur along the whole working length. 8) Why might the guide be unstable? –– Improper impression, cast fabrication and scanning. –– Loose teeth because of periodontal disease and damage. –– Large offset (distance between the tooth and the guide surface); 0.15 mm is recommended. –– Improperly stabilized guide while drilling. 9) Why might the drill path be inaccurate? –– Incorrect planning: false segmentation and alignment of CBCT and scan data. –– Artifacts on CBCT. –– Improperly stabilized guide while drilling. –– Dimensionally inaccurate drill and/or sleeve. –– Already accessed tooth.

  ­Reference

12.11  ­Summary Compared to freehand operation, using any type of guidance results in better accuracy. CBCT is widely available in dental practices. Static guides for endodontic treatments can be fabricated in the laboratory, as is done for guided implant placement. However, endodontics will not be easier with guides and other gadgets. Expert thinking, diagnosis and proper planning cannot be replaced. One should understand the technology, not be a victim of it. Gain the advantage of it, be more precise with manipulation and preserve tooth structure in a reasonable fashion. In the near future, dynamic guidance will revolutionize daily endodontic practice. Planned on the CBCT data, the avatar of the bur can be visualized on screen and controlled in real time in three dimensions. This will allow removal of as much tooth structure as minimally necessary for endodontic treatments, without the disadvantages of static guidance.

­References 1 Benyőcs G. Predictable root canal treatment of calcified maxillary incisor using a 3D printed drill-guide. Int J Oral Dent Sci 4, 2019; 7–12. 2 Andreasen FM, Zhijie Y. Occurrence of pulp canal obliteration after luxation injuries in the permanent dntition. Endod Dent Traumatol 1987; 3:103–15. 3 Nikui M, Kenny DJ. Clinical outcomes for incisor luxations in a pediatric population: III – lateral luxations. Dent Traumatol 2003;19:280–5. 4 Foreman PC, Soames J. Structure and composition of tubular and non-tubular deposits in root canal systems of human permanent teeth. Int Endod J 1988; 21:27–36. 5 Bauss O, Röhling J. The effect of pulp obliteration on pulpal vitality of orthodontically intruded traumatized teeth. J Endod 2008; 34:417–20. 6 Delivanis HP, Sauer G. Incidence of canal calcification in the orthodontic patient. Am J Orthod 1982;82:58–61. 6 Tahmaseb A, Wismeijer D. Computer technology applications in surgical implant dentistry: a systematic review. Int J Oral Maxillofac Implants 2014;24–52.29(suppl). 7 American Association of Endodontists. Endodontic case difficulty assessment and referral. www. aae.org/specialty/newsletter/endodontic-case-difficulty-assessment-referral/ 7 Oggini AO, Adekoya-Sofowora CA. Evaluation of radiographs, clinical signs and symptoms associated with pulp canal obliteration: an aid to treatment decision. Dent Traumatol 2009;25:620–5. 8 Lang H, Korkmaz Y, Schneider K.  Impact of endodontic treatments on the rigidity of the root. J Dent Res 2006;85:364–8. 9 Connert T, Zehnder M, Weiger R, et al. Microguided endodontics: accuracy of a miniaturized technique for apically extended access cavity preparation in anterior teeth. J Endod 2017; 43:787–90. 10 Zehnder MS, Connert T. Weiger R, et al. Guided endodontics: accuracy of a novel methodfor guided access cavity preparation and rootcanal location. Int Endod J 2016; 49:966–72. 11 Chanhee Byun DK-Y. Endodontic treatment of an anomalous anterior tooth with the aid of a 3-dimensional printed physical tooth model. J Endod 2015; 41:961–65. 12 Buchgreitz J, Buchgreitz M. Guided access cavity preparation using cone-beam computed tomography and optical surface scans – an ex vivo; study. Int Endod J 2016; 49:790–5.

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13 Cvek M, Granath L. Failures and healing in endodontically treated non-vital anterior teeth with posttraumatically reduced pulpal lumen. Acta Odontol Scand 1982;17: 223–8. 14 Jacobs CM-R. Clinical applications, accuracy and limitations of guided endodontics: a systematic review. Int Endod J 2020; 53: 214–31. 15 Buchanan L. Dynamic CT-Guided Endodontic Access Procedures. Dental Education Laboratories, Santa Barbara, CA, 2018. 16 Benyőcs G, Kinariwala N. Static guided non-surgical approach for posterior teeth. In: Kinariwala N, Samaranayake L (eds) Guided Endodontics. Springer, New York, 2021, pp. 135–49. 17 Clark DJ, Khademi J. Modern molar endodontic access and directed dentin conservation. Dent Clin North Am 2010; 54: 249–73. 18 Bóveda C, Kishen A. Contracted endodontic cavities: the foundation for less invasive alternatives in the management of apical periodontitis. Endod Top 2015;33(1):169–86. 19 Anderson J, Wealleans J, Ray J. Endodontic applications of 3D printing. Int Endod J 2018; 51:1005–18. 20 Georg D, Strbac DP. Guided modern endodontic surgery: a novel approach for guided osteotomy and root resection. J Endod 2017; 43:496–501.

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13 Clinical Case 13 – Management of pulpal floor perforation with periapical lesion in the mesial root Zaher Al Taqi

Introduction to the case: a case of retreatment with an apical lesion in the mesial root and perforation in the floor of the pulp champer along with a periapical radiolucency in the mesial root.

1 ­ 3.1  ●● ●● ●●

Patient information

Age: 22 years old. Gender: male. Medical history: not significant.

13.2 ­Tooth ●● ●●

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Identification: mandibular left first molar (Tooth 36). Dental history: initiated root canal treatment a few days previously. Episodes of pain on and off since the treatment was started. Pain and difficulty in chewing in the mandibular left posterior region for the last few days. Clinical examination findings: PFM crown present on Tooth 36  with initiated access opening covered with a temporary filling. The tooth is tender to percussion. Preoperative radiological assessment: periapical radiograph shows Tooth 36 with PFM crown and suspected pulpal floor perforation. In addition, periapical radiolucency can be seen associated with mesial root of Tooth 36. Radiolucent changes can also be seen in the furcation area. In addition, Tooth 35 has been be root canal treated with full-coverage post endodontic restoration and Tooth 37 is suspected to have a crown with inadequate root canal treatment (Figure 13.1). Diagnosis (pulpal and periapical): initiated root canal treatment with symptomatic apical periodontitis.

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Figure 13.1  Preoperative radiograph showing Tooth 36 with suspected furcation perforation and radiolucent changes in the furcation area. There is periapical radiolucency along the mesial root of Tooth 36. PFM crown on Tooth 37 with suspected inadequate root canal treatment.

13.3 ­Treatment plan ●●

●●

●●

●●

●●

Preliminary procedures: local anaesthesia to be given, followed by isolation of the tooth with rubber dam. The temporary filling to be removed and older amalgam restoration removed. Perforation site to be located. Treatment plan for management of the endodontic mishap –– Modify the endodontic access cavity to achieve a straight-line access. –– Removal of older filling material from the access cavity. –– Locate the site of pulpal floor perforation. Disinfect and seal the perforation. –– Adequately clean and shape the canals and place intracanal medicament. –– Obturate the tooth when it becomes asymptomatic. Endodontic mishap repair procedure –– After removal of amalgam restoration, the perforation site was clearly visible under the microscope (Figure 13.2). –– Disinfection of the perforation site was carried out (Figures 13.3 and 13.4) and access to the canals was gained (Figure 13.5). –– Sequential instrumentation was done using rotary files until size F3 of ProTaper before placing MTA over the perforation (Figures 13.6 and 13.7). –– Bleeding from the perforation site controlled, Canal orifices blocked with Teflon and the area prepared to be sealed with MTA (Figure 13.8). –– Care was taken to touch the perforation site as little as possible, as this would enlarge the perforation and initiate bleeding. Irrigation (solution and technique): 3% sodium hypochlorite and 17% EDTA used alternately and irrigant activation by sonic activation using the EndoActivator for 30 seconds after use of every instrument. The perforation was cleaned with 2.5% sodium hypochlorite. Final irrigation protocol: 2% chlorhexidine along with sonic activation using the EndoActivator for 1 minute in the canals.

13.3 ­Treatment pla

Figure 13.2  Perforation site after removal of the crown and previous amalgam restoration.

Figure 13.3  Cleaning of the endodontic access cavity in progress for better visualization of the perforation.

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Figure 13.4  The perforation after being cleaned and disinfected.

Figure 13.5  Access to the canals gained, cleaning and shaping of the root canals before closing the perforation with MTA.

13.3 ­Treatment pla

Figure 13.6  Perforation along with cleaned and shaped root canals. Irrigant can be seen in the canals for disinfection.

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Pulpal floor perforation repair: after removal of the granulation tissue and cleaning the perforation with sodium hypochlorite, the canal orifices were covered with Teflon (Figure 13.8). MTA was condensed over the the perforation site and dried with a microbrush (Figures 13.9 and 13.10). Obturation (material and technique): epoxy resin-based sealer (AH Plus®) was used along with gutta-percha as the core obturating material (Figure 13.10). Single cone obturation technique was used to obturate the canals. The obturation and perforation repair was verified on the radiograph (Figure 13.11).

Figure 13.7  Cleaned and shaped canals. Dry and prepared perforation for receiving MTA.

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Figure 13.8  Blockage of canal orifices with Teflon so that MTA does not enter the canals while placing it on the perforation.

Figure 13.9  Placement of MTA over the perforation and removal of Teflon from the canal orifices.

13.4 ­Technical aspect

Figure 13.10  Obturation of the root canals along with placement of MTA over the perforation site.

13.4 ­Technical aspects ●●

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The perforation was debrided by copiously irrigating the area with 2.5% sodium hypochlorite and normal saline. Care needs to be taken not to enlarge (touch) the perforation area while cleaning and shaping the canals. The perforation site should not be touched with instruments as this might cause excessive bleeding and hamper vision. Use of a microscope for magnification is mandatory in such cases.

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Figure 13.11  Immediate postoperative radiograph showing complete root canal treatment, perforation repair and fiber post cementation in the distal canal of Tooth 36.

13.5 ­Follow-up ●●

At 1-year follow-up, the patient was asymptomatic. The radiograph shows healing and decrease in the size of radiolucency in the furcation area (Figure 13.12).

13.6 ­Learning objectives ●● ●● ●●

●●

Understand that the use of magnification is essential to see the perforation site and the canals. Understand the need for disinfecting the perforation before placing MTA over it. The first task is to clearly see the perforation, the second is to use copious irrigation to disinfect it. Avoid touching the perforation site during cleaning and shaping of the canals. Figure 13.12  One-year recall showing healing of the furcation area and the mesial radiolucency.

13.7  ­How can this endodontic ●●

●●

●●

mishap be avoided

Understand that before sealing the perforation, proper debridement of the area is essential for better outcomes. After debriding the perforation site, examine the area with adequate magnification (loupes or microscope) to rule out the presence of any foreign object or debris. Use of appropriate perforation repair material is required to treat the endodontic mishap.

13.7 ­How can this endodontic mishap be avoided? ●●

●● ●● ●●

Properly study the preoperative radiograph for the angulation of the tooth, position and size of the pulp chamber. Proper use of magnification tools is necessary. Predetermine the depth of the bur to be inserted for preparation of the endodontic access cavity. Use an Endo-Z bur for preparation of the endodontic access cavity. This non-cutting bur prevents overcutting of the pulpal floor.

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14 Clinical Case 14 – Management of root canal treatment failure with missed canal anatomy and inadequate obturation Eugen Buga

Introduction to the case: case of symptomatic periodontitis associated with a previously inadequate root canal treatment. Short filling and missed root canal failure.

14.1 ­Patient information ●● ●● ●●

Age: 37 years old. Gender: male. Medical history: non-contributory.

14.2 ­Tooth ●● ●●

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Identification: right maxillary second premolar (Tooth 15). Dental history: chief complaint: the tooth has been causing pain since the root canal was treated and lately the pain has increased. Referral note: short root canal treatment and suspected missed root canal. Clinical examination findings: the tooth is painful to percussion and the buccal vestibule is painful on palpation. Periodontal probing was within normal limits. Preoperative radiological assessment: the two-dimensional periapical radiograph revealed a previously treated Tooth 15  with obturation of the root canal system remaining short of the radiographic apex. Periapical radiolucency could be detected in the preoperative two-dimensional periapical radiograph (Figure  14.1). Suspected missed root canal can also be seen in the preoperative radiograph. Also, the presence of an extra root irt 15 is suspected. Diagnosis (pulpal and periapical): symptomatic apical periodontitis with root canal failure due to missed root canal.

Clinical Atlas of Retreatment in Endodontics, First Edition. Edited by Viresh Chopra. © 2021 John Wiley & Sons Ltd. Published 2021 by John Wiley & Sons Ltd. Companion website: www.wiley.com/go/chopra/retreatment

­14.  Treatment plan

Figure 14.1  Periapical radiograph showing a previously treated tooth with an obturation of the root canal system remaining short of the radiographic apex. Periapical radiolucency can be detected. Also, the presence of an extra root is suspected. Interdental bone loss is also evident between Teeth 15 and 16.

1 ­ 4.3  Treatment plan ●●

●●

Preliminary procedures: buccal infiltration anaesthesia was administered. The tooth was isolated with rubber dam. Access was achieved with diamond burs under the magnification provided by a six-step operating microscope. Secondary caries removal was done and older gutta-perchas were located (Figure  14.2). Pre-endodontic wall build-up was carried out before starting the endodontic retreatment procedure (Figure 14.3). Treatment plan for management of the endodontic mishap: the coronal gutta-percha was removed with Gates Glidden burs and rotary retreatment files. No solvent was used as it was judged

Figure 14.2  Isolation and removal of secondary caries and location of older gutta-percha.

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Figure 14.3  Pre-endodontic wall build-up done before starting the retreatment procedure.

unnecessary. The gutta-perchas were traced and the design of the endodontic access cavity was assessed. The access cavity was found to be inadequate and it was necessary to extend it (Figure 14.4). Minimal extension of the access cavity was done to locate the missed mesiobuccal canal (Figure 14.5). The proper length was regained and verified with an electronic apex locator. The canal was enlarged to a 40/04 size. Disinfection was achieved with positive syringe irrigation of 5% solution of NaOCl. The missed mesiobuccal canal was cleaned and disinfected (Figure 14.6). After the canal Figure 14.4  Location of suspected extra canals traced and the need for extension of the access cavity assessed. The location of a missed mesiobuccal canal is also marked.

Figure 14.5  The missed mesiobuccal canal located by minimally extending the endodontic access cavity.

­14.  Treatment plan

Figure 14.6  Disinfection process with the irrigant in action in the missed mesiobuccal canal.

enlargement, some gutta-percha remnants were seen under magnification firmly attached in the canal dentinal walls. The canal was flooded with 17% EDTA for 5 minutes and then rinsed with 5% NaOCl. Alternate use of EDTA and NaOCl during retreatment can facilitate the debonding of wellattached obturation materials. ●●

●●

●● ●● ●●

●●

Endodontic mishap repair procedure: after removal of the older gutta-percha, an attempt to modify the endodontic access cavity was made in order to locate the missed mesiobuccal canal. The object of modifying the access cavity is to keep the entrance of the mesiobuccal canal patent for the disinfection process and cleaning and shaping to be effective and for the obturation material to reach. Canal preparation (or retreatment procedure): after removal of the bulk material of the previous obturation, the canals were enlarged with rotary controlled memory files up to 40/04 apical enlargement. The extra canals were also shaped with the same technique (Figure 14.7). Irrigation (solution and technique): 5% NaOCl; passive ultrasonic irrigation (3 × 20 seconds). Final irrigation protocol: 17% EDTA (syringe irrigation) for 3 minutes. Obturation (material and technique): epoxy resin-based sealer (AH Plus®) was used along with gutta-percha as the core obturating material. The technique used was warm vertical compaction and the obturation was verified on the radiograph. Additional information: the obturation in the extra canals could be appreciated in the postoperative radiograph (Figure 14.8).

Figure 14.7  The final enlarged missed mesiobuccal canal up to 40/04.

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Figure 14.8  Immediate postoperative radiograph verifying the obturation of the root canal system.

14.4 ­Technical aspects The internal anatomy of human teeth is complicated, consisting of a central main part and associated extra canals. Failure to incorporate the whole root canal system in the endodontic process might result in persistence of the disease. The cleaning and shaping procedure during retreatment should address the whole root canal system.

­14.5  Follow-up The 6-month and 1-year follow-up clinical and radiographic examinations revealed an asymptomatic tooth and complete healing of the periapical lesion (Figure 14.9).

14.6 ­Learning objectives ●● ●● ●● ●●

●● ●●

Understand the need to read the preoperative radiograph properly. Understand the complexity of the root canal system. Understand the limitations of two-dimensional imaging. Understand the need to verify the endodontic access cavity before proceeding to the next step. Understand the need to look for extra canals and extra roots. Understand the importance of incorporating the whole root canal system in the disinfection process during retreatment.

14.7  ­How can this endodontic

mishap be avoided

Figure 14.9  Six-month recall and 1-year recall radiographs showing complete healing of the periapical lesion irt 15.

14.7 ­How can this endodontic mishap be avoided? The astute clinician always bears in mind during initial treatment that we are not dealing with a canal but a complicated canal system which may have extra roots/canals in which bacteria can spread and remain unaffected if not treated. The clinician should be able to read the preoperative radiograph clearly and appreciate the presence of extra canals or roots shown in the radiograph. Even if the radiograph does not show extra canals, the clinician should be able to visualize and explore the endodontic access cavity for extra canals or clinical signs of necessary extension to locate and complete the access cavity.

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15 Clinical Case 15 – Management of root canal treatment failure with inadequate obturation, hidden fractured instrument and ledge formation in a severely curved mandibular molar Eugen Buga

Introduction to the case: case of symptomatic apical periodontitis associated with a previously inadequate root canal treatment. Short obturation in all the canals and severely curved distal root of a mandibular molar. While removing the older obturation, a fractured instrument was found and removed from the distal canal.

15.1 ­Patient information ●● ●● ●●

Age: 27 years old. Gender: male. Medical history: non-contributory.

15.2 ­Tooth ●● ●●

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●●

●●

Identification: right mandibular second premolar (Tooth 46). Dental history: the tooth started to be painful on biting 2 weeks back. Now, slight swelling is also present. Clinical examination findings: the tooth is tender to percussion and the buccal vestibule is painful on palpation. In addition, slight intraoral swelling is present on the buccal vestibule area. Periodontal probing was within normal limits. The tooth has occlusal temporary restoration. Preoperative radiological assessment: the two-dimensional periapical radiograph revealed a previously treated tooth 46 with an obturation of the root canal system remaining short of the radiographic apex in all the canals. Periapical radiolucency can be detected associated with the distal root (Figure 15.1). Severe curvature in the distal root can also be seen. The mesial canals are also short in obturation, but the apical part of the mesial canals seems to be patent. Diagnosis (pulpal and periapical): symptomatic apical periodontitis with chronic apical abscess and root canal failure due to short obturation.

Clinical Atlas of Retreatment in Endodontics, First Edition. Edited by Viresh Chopra. © 2021 John Wiley & Sons Ltd. Published 2021 by John Wiley & Sons Ltd. Companion website: www.wiley.com/go/chopra/retreatment

15.3 ­Treatment pla

Figure 15.1  Periapical radiograph showing the previously treated tooth with an obturation of the root canal system remaining short of the radiographic apex. Periapical radiolucency can be detected on the radiograph associated with the distal root. The distal root can be seen severely curved. The mesial canals are suspected to be very narrow.

15.3 ­Treatment plan ●●

●●

Preliminary procedures: buccal infiltration anaesthesia was administered. The tooth was isolated with rubber dam. The temporary restoration was removed to gain access under the magnification provided by a dental operating microscope. Secondary caries removal was carried out and older gutta-perchas were located (Figure 15.2). Treatment plan for management of the endodontic mishap: the coronal gutta-percha was removed with Gates Glidden burs and rotary retreatment files D1, D2 and D3 (Dentsply). The gutta-perchas

Figure 15.2  Isolation and removal of the temporary restoration done to gain access to the older gutta-percha.

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Fractured Instrument

Figure 15.3  Presence of the fractured instrument seen under the dental operating microscope.

●●

were traced and the design of the endodontic access cavity was assessed. During the removal of gutta-percha from the distal canal, a hard obstruction was felt. At first, it was suspected to be a ledge but on observing under a microscope, a fractured instrument could be clearly seen (Figure 15.3). While removing the older gutta-percha, the fractured instrument became loose in the canal. It was easily removed with endodontic ultrasonic tips (Spartan) (Figure 15.4). Once the older gutta-percha was removed from the mesial canals, 08 and 10 K-files were used to determine the working length with the help of an electronic apex locator (Figures 15.5 and 15.6). The proper length was regained and verified with the apex locator. Older gutta-percha was removed from the distal canals in the same way as in the mesial canals. However, due to severe curvature in the distal canal, the canal patency was gained by precurving the 10 K-file and Figure 15.4  Removal of the loose fractured instrument from the distal canal with the help of endodontic ultrasonic tips.

15.3 ­Treatment pla

Figure 15.5  Clinical picture showing use of 08 K-file to check canal patency and working length.

Figure 15.6  Periapical radiograph to confirm canal patency as well as working length in the mesial canal.

finding the path with a watch winding motion. Since the curvature was acute, it required patience and copious irrigation to regain canal patency and determine working length. The mesial and distal canals were enlarged up to F2 size. Disinfection was achieved with positive syringe irrigation of 5% NaOCl. The endodontic access cavity was explored for any missed canals (Figure 15.7).

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Figure 15.7  Disinfection process with the irrigant in action and exploration of the endodontic access cavity for the presence of any extra canals.

●●

●●

●● ●● ●●

Endodontic mishap repair procedure: after removal of older gutta-percha, attempts to remove the fractured instrument from the distal canal were made. Since the instrument became loose during gutta-percha removal, it was easy to remove with endodontic ultrasonic tips. After removal of the fractured instrument, a precurved 10 K-file was used to negotiate the acute apical curvature of the distal canal. The objective of precurving is to find the path of the main canal with the help of a watch winding motion. Copious irrigation was used during the whole procedure to reduce the risk of fracture due to friction. Canal preparation (or retreatment procedure): after removal of the previous obturation, the canals were enlarged with rotary controlled memory files up to F2 apical enlargement. Irrigation (solution and technique): 5% NaOCl; passive ultrasonic irrigation (3 × 20 seconds). Final irrigation protocol: 17% EDTA (syringe irrigation) for 3 minutes. Obturation (material and technique): epoxy resin-based sealer (AH Plus®) was used along with gutta-percha as the core obturating material. The technique used was warm vertical compaction and the obturation was verified on the radiograph (Figure 15.8).

15.4 ­Technical aspects The anatomy of human teeth is complicated, consisting of a central main part and associated with severe curvatures and sometimes extra canals. Failure to negotiate the full length of the root canal system during the endodontic process might result in inadequate cleaning and shaping, leading to persistence of the disease. Precurved files should be used to achieve patency in curved canals. Along with precurved files, copious irrigation needs to be used with every instrument to decrease the risk of instrument fracture due to friction. Although it is true for all endodontic cases, special care should be taken not to overuse the files specifically with curved canals as they can break easily in such cases.

15.6 ­Learning objective

Figure 15.8  The final obturation verified on the radiograph.

The cleaning and shaping procedure during retreatment should address the whole root canal system.

15.5 ­Follow-up The 6-month follow-up clinical and radiographic examination revealed an asymptomatic tooth and complete healing of the periapical lesion.

15.6 ­Learning objectives ●● ●●

●● ●● ●● ●● ●● ●●

Understand the need to read the preoperative radiograph properly. Understand the limitations of a two-dimensional radiograph as it did not show the fractured instrument in this case. Understand and appreciate the anatomy of the root canal system. Modify the treatment steps as per the anatomy of the root canal. Understand the need to verify the endodontic access cavity before proceeding to the next step. Understand the need to observe under magnification. Understand the importance of precurving the initial instruments to gain canal patency. Understand the importance of incorporating the whole root canal system in the disinfection process during retreatment.

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15.7 ­How can this endodontic mishap be avoided? A clinician should be able to read the preoperative radiograph clearly and appreciate the presence of curvatures, extra canals or roots shown in the radiograph. After reading the radiograph, the clinician should be able to modify the steps of the treatment as per the requirement of the tooth anatomy. Sometimes, the radiograph might not show the complete picture, in which case the clinician should pause, have a good look under magnification and confirm the direction of protocol. The whole length of the root canal system should be cleaned and disinfected to the maximum limit possible.

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16 Clinical Case 16 – Management of root canal treatment with an instrument fracture in a mandibular molar Viresh Chopra

Introduction to the case: case of symptomatic apical periodontitis associated with a previous attempt at root canal treatment. During the cleaning and shaping procedure, an instrument fractured in one of the mesial canals and then the case was referred for removal of the instrument and completion of the root canal treatment.

16.1 ­Patient information ●● ●● ●●

Age: 27 years old. Gender: female. Medical history: non-contributory.

16.2 ­Tooth ●● ●● ●●

●●

●●

Identification: right mandibular second molar (Tooth 47). Dental history: chief complaint: I have pain and a throbbing sensation in my right lower tooth. Clinical examination findings: the tooth was tender to percussion and had a temporary restoration. Periodontal probing was within normal limits. Preoperative radiological assessment: the two-dimensional periapical radiograph revealed an instrument fracture in Tooth 47. Also, the tooth has a occlusodistal restoration and the root canal has not been completed. Tooth 46 has an inadequate obturation short of the radiographic apex (Figure 16.1). Diagnosis (pulpal and periapical): symptomatic apical periodontitis with instrument fracture in the tooth.

16.3 ­Treatment plan ●●

First visit: buccal infiltration anaesthesia was administered. The tooth was isolated with rubber dam. The temporary restoration was removed to gain access under magnification provided by a dental operating microscope (Figure 16.2). The endodontic access cavity was modified for better

Clinical Atlas of Retreatment in Endodontics, First Edition. Edited by Viresh Chopra. © 2021 John Wiley & Sons Ltd. Published 2021 by John Wiley & Sons Ltd. Companion website: www.wiley.com/go/chopra/retreatment

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Figure 16.1  Periapical radiograph showing an instrument fracture in Tooth 47. Also, inadequate obturation of the root canal system remaining short of the radiographic apex in Tooth 46 can be seen. Periapical radiolucency can be detected on the radiograph associated with distal root of 46.

Figure 16.2  Removal of temporary restoration and first look at the access cavity.

visibility with the help of endodontic ultrasonic tips for access preparation under the dental operating microscope (Video 1). After gaining access to the pulp chamber, the mesiolingual canal was checked for the fractured instrument. The instrument was visible under the dental operating microscope. The mesiobuccal and distal canals were checked for canal patency and working length and verified on a radiograph (Figures 16.3 and 16.4). The working length was adjusted as during the radiograph, the patient had closed her mouth, due to which the endodontic files had gone beyond the estimated working length. The MB and distal canals were cleaned and shaped up to rotary F2 files. Once the patent canals were cleaned and shaped, intracanal medicament was placed and the patient scheduled for a second visit. ●● Second visit: the second appointment was planned for instrument removal. The instrument was visualized under the microscope (Figure 16.5). The coronal part of the canal was enlarged to clearly see the instrument and gain proper access to it (Figure 16.6). Endodontic ultrasonic tips were used to remove dentine around the fractured instrument to loosen it. Once the instrument became loose, the instrument removal loop from the Yoshi Teruachi file retrieval kit (TFRK) was used. The loop was engaged on the coronal exposed head of the fractured instrument and locked tight. Once tight, the instrument was pulled and lifted out of the root canal (Figure 16.7).

16.3 ­Treatment pla

Figure 16.3  Checking the canal patency in MB and distal canals and also taking working length.

Figure 16.4  Verification of working length. The patient had closed her mouth due to which the files went beyond the measured working length.

Figure 16.5  Clinical picture showing the fractured instrument in the mesiolingual canal.

Figure 16.6  Enlargement of the coronal part of the canal to gain clear access to the fractured instrument.

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Figure 16.7  Engagement of the fractured instrument head with the loop from the TFRK kit and removal of the instrument out of the canal.

Figure 16.8  Final cleaning and shaping of the three canals. Exploration of the access cavity for any extra canals present.

Once the instrument was removed, the canal was prepared with rotary instrumentation up to F2 size. Disinfection was achieved with positive syringe irrigation of 5% NaOCl. The endodontic access cavity was explored for any missed canals (Figure 16.8) and the master cones were placed to check the cone fit at the correct working length (Figure 16.9) and verified on a radiograph (Figure 16.10). ●● ●● ●●

Irrigation (solution and technique): 5% NaOCl; passive ultrasonic irrigation (3 × 20 seconds). Final irrigation protocol: 17% EDTA (syringe irrigation) for 3 minutes. Obturation (materials and technique): epoxy resin-based sealer (AH Plus®) was used along with gutta-percha as the core obturating material. The technique used was warm vertical compaction and the obturation verified on the radiograph (Figures 16.11 and 16.12). Figure 16.9  Placement of guttaperchas inside the canal to check the master cone fit.

16.3 ­Treatment pla

Figure 16.10  Radiographic verification of the master cones up to the working length.

Figure 16.11  Final obturation with gutta-perchas.

Figure 16.12  Radiographic verification of obturation.

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16.4 ­Technical aspects The morphology and anatomy of root canals are complex, consisting of severe curvatures and sometimes extra canals. Failure to negotiate the curvatures in the root canal system during the endodontic process might result in inadequate cleaning and shaping, leading to short obturation and persistence of diseased tissue. Precurved files should be used to achieve canal patency in curved canals. Along with precurved files, copious irrigation needs to be done with every instrument to decrease the risk of instrument fracture due to friction. However, as for all endodontic cases, special care should be taken not to overuse the files, specifically with curved canals, as the files can break easily in such cases. The cleaning and shaping procedure during retreatment should address the whole root canal system. If the instrument fractures, then a decision should be made between removing the instrument, bypassing the instrument and leaving it in the canal. In this case, the length of the instrument was greater, it could not be bypassed and the patient was symptomatic. In view of these factors, the decision was made to remove the instrument and the patient was informed.

16.5 ­Follow-up The 6-month follow-up clinical and radiographic examination revealed an asymptomatic tooth and healing of the periapical area (Figure 16.13). The patient did not want to have the post endodontic full-coverage restoration (crown) till now.

16.6 ­Learning objectives The reader should be able to: ●● understand the need to read the preoperative radiograph properly ●● understand the limitation of a two-dimensional radiograph as it sometimes does not show the canal curvatures Figure 16.13  Six-month recall.

16.7  ­How can this endodontic ●● ●● ●● ●● ●● ●● ●●

mishap be avoided

understand and appreciate the anatomy/shape of the root canal system plan/modify the treatment steps as per the anatomy/shape of the root canal understand the need to verify the endodontic access cavity before proceeding to the next step understand the need to limit the overuse of endodontic files in the canals understand the need to perform endodontics under magnification understand the importance of precurving initial instruments to gain canal patency understand the importance of incorporating the whole root canal system in the disinfection process during retreatment.

16.7 ­How can this endodontic mishap be avoided? A clinician should be able to read the preoperative radiograph clearly and appreciate the presence of curvatures, extra canals or roots shown in the radiograph. After reading the radiograph, the clinician should be able to modify the treatment steps as per the requirements of the tooth anatomy. The clinician needs to stick to the endodontic protocol of precurving the file, use of irrigants and lubricants and make sure never to work in a dry canal. In such a case, the clinician should take a pause, have a good look under magnification and confirm the direction of protocol. The whole length of the root canal system should be cleaned and disinfected to the maximum limit possible.

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17 Clinical Case 17 – Management of a mandibular molar with fractured instrument extending in the periapical area Zaher Al Taqi

Introduction to the case: a case of retreatment with fractured instrument extending in the periapical area in the mesial canal and inadequate obturation in the distal canals.

17.1 ­Patient information ●● ●● ●●

Age: 28 years old. Gender: male. Medical history: not significant.

17.2 ­Tooth ●● ●●

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●●

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Identification: mandibular right first molar (Tooth 46). Dental history: root canal treatment a few weeks back. Episodes of pain on and off since the treatment was completed. Pain and difficulty in chewing in the mandibular right posterior region for the last few days. Clinical examination findings: faulty temporary restoration in relation to Tooth 46 (Figure 17.1). The tooth was tender to percussion. Preoperative radiological assessment: inadequately performed root canal treatment with a separated instrument in the mesial canal extending beyond the apical foramen; inadequate obturation in the distal canal. Bothe the mesial and distal roots are associated with periapical radiolucency (Figure 17.2). Diagnosis (pulpal and periapical): failed root canal treatment with symptomatic apical periodontitis.

17.3 ­Treatment plan ●●

Preliminary procedures: local anaesthesia to be performed, followed by isolation of the tooth with rubber dam. The temporary restoration was removed and access to previous endodontic access gained. Older gutta-perchas were located (Figure 17.3).

Clinical Atlas of Retreatment in Endodontics, First Edition. Edited by Viresh Chopra. © 2021 John Wiley & Sons Ltd. Published 2021 by John Wiley & Sons Ltd. Companion website: www.wiley.com/go/chopra/retreatment

17.3 ­Treatment pla

Figure 17.1  Preoperative clinical picture showing cracked temporary restoration mesio-occlusally. Bucco-disto-lingual thin walls can also be seen.

Figure 17.2  Preoperative radiograph showing MO temporary restoration and the fractured instrument extending in the periapical area in the mesial canal. Inadequate short obturation in distal canals. Mesial and distal roots are associated with periapical radiolucency.

Figure 17.3  Removal of temporary restoration, access to previous endodontic cavity and location of older gutta-percha.

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17  Clinical Case 17 ●●

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●●

●●

●●

●●

Treatment plan for management of the endodontic mishap –– Modify the endodontic access cavity to achieve a straight-line access. –– Removal of older root canal filling from the distal canals. –– Complete cleaning and shaping of the distal canals up to the working length. –– Locate the fractured instrument. Attempt to remove the separated instrument in the mesial canal. –– Adequately clean and shape the canals and place intracanal medicament. –– Obturate the tooth when it becomes asymptomatic. Endodontic mishap repair procedure –– The fractured instrument was located in the mesiolingual canal under the microscope. –– Coronal flaring done in order to see the head of the instrument clearly (Figure 17.4). –– Loosening of the fractured instrument was done with the help of thin ultrasonic tips used on the inner wall of the root canal. Care was taken not to remove excessive dentine during the use of ultrasonic tips. Continuous flushing with endodontic irrigant was performed throughout the procedure (Figure 17.5). Once the instrument was loose, a BTR Pen was used to catch the instrument and bring it out of the canal (Figure 17.6), which was verified with a periapical radiograph (Figure 17.7). –– Sequential instrumentation was done using rotary files until ProTaper size F3. Irrigation (solution and technique): 3% sodium hypochlorite and 17% EDTA used alternately and irrigant activation by sonic activation using the EndoActivator for 30 seconds after use of every instrument. Final irrigation protocol: 2% chlorhexidine along with sonic activation using the EndoActivator for 1 minute. Obturation (material and technique): AH Plus® used as endodontic sealer along with gutta-percha as the core material. Warm vertical condensation technique was used to obturate the canals up to the full working length and verified on the radiograph (Figure 17.8). Removal of instrument and obturation was confirmed with a postoperative final radiograph. Figure 17.4  The head of the fractured instrument is clearly visible after coronal flaring of the canal.

17.3 ­Treatment pla

Figure 17.5  Removal of the fractured instrument in progress along with continuous flushing of the canal with irrigant.

Figure 17.6  Removal of the fractured instrument with a BTR loop.

Figure 17.7  Radiographic verification of the removal of the fractured instrument.

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Figure 17.8  Final obturation of the mandibular molar after removal of the fractured instrument.

17.4 ­Technical aspects ●●

●●

●●

●●

The perforation was debrided by copiously irrigating the area with normal saline followed by 2% chlorhexidine. Care needs to be taken not to enlarge (touch) the strip perforation area while using ultrasonic tips for removal of the fractured instrument. The perforation site should not be touched with instruments as this might cause excessive bleeding and hamper vision. Use of a microscope for magnification is mandatory in such cases.

17.5 ­Learning objectives ●● ●● ●●

●● ●●

Use of magnification is essential to see the fractured instrument. Removal of the instrument must be performed strictly under high magnification. First, clearly visualize the fractured instrument, then gain access to the instrument and finally loosen the instrument and use copious irrigation to facilitate its removal from the canal. Avoid overcutting of dentinal walls for removal of the instrument. Use appropriate techniques and instruments for instrument removal.

17.6  ­How can this endodontic

mishap be avoided

17.6 ­How can this endodontic mishap be avoided? ●●

●● ●● ●● ●● ●●

Properly study the preoperative radiograph for the angulation of the tooth, position and size of the pulp chamber. Straight-line endodontic access cavity is necessary. Overuse of endodontic files should be avoided to decrease the incidence of instrument fracture. Copious irrigation and lubrication should be used to avoid instrument separation. Sequential use of instruments is necessary to clean and shape the canals. Correct angulation to be maintained throughout the cleaning and shaping procedure.

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18 Clinical Case 18 – Management of root canal treatment failure with inadequate obturation and apically calcified canals Viresh Chopra

Introduction to the case: case of symptomatic apical periodontitis associated with a previous root canal treatment with inadequate obturation in a maxillary premolar.

18.1 ­Patient information ●● ●● ●●

Age: 29 years old. Gender: male. Medical history: non-contributory.

18.2 ­Tooth ●● ●●

●●

●●

●●

Identification: right maxillary second premolar (Tooth 15). Dental history: chief complaint: I am having pain when I eat or put pressure on my tooth. History of previous root canal treatment done on right upper maxillary second premolar. Clinical examination findings: the tooth is tender to percussion and has an all-ceramic crown on it. Periodontal probing was within normal limits. Preoperative radiological assessment: the periapical radiograph revealed previous root canal treatment in Tooth 15. The obturation is short of the radiographic apex. The root is associated with periapical radiolucency. The apical part of the canals (which are unobturated) are suspected to be calcified (Figure 18.1). Diagnosis (pulpal and periapical): symptomatic apical periodontitis with inadequate root canal treatment.

18.3 ­Treatment plan The patient was informed about the problem and advised to have retreatment of Tooth 15. However, the treatment was planned through the ceramic crown. If the all-ceramic crown comes out during the treatment, then it will be replaced with a new crown. Clinical Atlas of Retreatment in Endodontics, First Edition. Edited by Viresh Chopra. © 2021 John Wiley & Sons Ltd. Published 2021 by John Wiley & Sons Ltd. Companion website: www.wiley.com/go/chopra/retreatment

18.3 ­Treatment pla

Figure 18.1  Periapical radiograph inadequate root canal treatment in Tooth 15. Periapical radiolucency associated with the root of 15 can also be seen.

●●

First visit: buccal infiltration anaesthesia was administered and the tooth was isolated with rubber dam. The tooth was visualized under the microscope preoperatively (Figure 18.2). Endodontic access was prepared through the ceramic crown and older gutta-perchas located (Figure 18.3). The coronal part of the gutta-perchas in the pulp chamber were removed with ultrasonic scaler (Video 1). Gutta-perchas inside the root canal were removed with the help of the XP-endo® Shaper file from FKG used at 1000 rpm (Figure  18.4) (Video 2). Intracanal medicament was placed and the patient scheduled for a second appointment.

Figure 18.2  Tooth 15 with all-ceramic crown before starting the retreatment procedure.

Figure 18.3  Endodontic access cavity made through the ceramic crown. Older gutta-perchas located.

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Figure 18.4  Removal of gutta-perchas with XP-endo Shaper files from FKG.

●●

●●

Second visit: while placing the clamp, the all-ceramic crown came out and the patient was informed. Once the previous gutta-perchas were completely removed, 08 K and 10 K endodontic files were precurved and used in an attempt to open the calcified canals. C+ files were also used to open up the apically calcified part of the root canals. Once the calcified part was negotiated, working length was determined with an electronic apex locator and verified with a periapical radiograph (Figure 18.5). In the initial phase of cleaning and shaping, the XP-endo Shaper file was used with copious irrigation (Video 3). Both the canals were finally prepared up to F2 ProTaper files and master cones verified for fit on the periapical radiograph (Figure 18.6). The XP-endo Shaper file was again used to apply endodontic sealer inside the canals. The master cones were coated with the sealer and placed inside the canals. Warm vertical condensation technique was used to obturate the canals (Video 4). Both the canals were obturated and the pulp chamber cleaned of any gutta-percha or sealer (Figure 18.7). An immediate postoperative radiograph was taken to verify the final obturation. Obturation (materials and technique): AH Plus® as endodontic sealer and ProTaper F2 gutta-perchas. Figure 18.5  Periapical radiograph verifying the working length.

18.4 ­Technical aspect

Figure 18.6  Periapical radiograph verifying the master cones for obturation.

Figure 18.7  Obturation of both the canals and the pulp chamber free of any gutta-percha or endodontic sealer.

18.4 ­Technical aspects The morphology and anatomy of root canals are complex, consisting of severe curvatures and sometimes extra canals. There are many factors due to which root canals or parts of root canals may become calcified. Failure to negotiate the calcified part of the root canal system in the endodontic process might result in inadequate cleaning and shaping, leading to short obturation and persistence of the diseased tissue. Precurved files, C+ files with copious irrigation and dentine softeners may be used to open calcified canals and achieve canal patency. Tactile sensation and patience play a vital role in negotiating calcified canals. However, as for all endodontic cases,

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18  Clinical Case 18

special care should be taken not to overuse the files, specifically with curved canals, as the files can break easily in such cases. In this case, the XP-endo Shaper was used to remove gutta-percha from the canals. This tool has an advantage due to its three-dimensional spiral morphology. The unique design enables the file to engage the material and pull it out of the canal with its rotations. In addition, the file rotates in a three-dimensional direction and removes any material adhering to the canal walls. However, the file is recommended to be used at 1000 rpm for gutta-percha removal. The initial phase of cleaning and shaping procedure was done with the XP-endo Shaper to ensure complete removal of previous gutta-percha or sealer from the walls of the root canals. Copious irrigation should be maintained throughout the procedure and endodontic files should not be used in dry canals.

18.5 ­Follow-up The 6-month follow-up clinical and radiographic examination revealed an asymptomatic tooth and healing of the periapical area (Figure 18.8).

18.6 ­Learning objectives ●● ●● ●● ●● ●● ●●

●●

Understand the need to negotiate the full length of the canal. Understand and appreciate the anatomy/shape of the root canal system. Modify the treatment steps as per the anatomy/shape of the root canal. Understand the need to limit the use of endodontic files in the canals. Understand the importance of precurving initial instruments to gain canal patency. Understand the importance of incorporating the whole root canal system in the disinfection process during retreatment. Clinically decide which instrument should be used for a particular step during the endodontic treatment or retreatment.

Figure 18.8  Periapical radiograph to verify the obturation.

18.7  ­How can this endodontic

mishap be avoided

Figure 18.8  Six-month recall radiograph showing intact crown, obturation and ongoing healing of the periapical area.

18.7 ­How can this endodontic mishap be avoided? A clinician should be able to read a preoperative radiograph clearly and appreciate the presence of any calcification in the canal or pulp chamber. After reading the radiograph, the clinician should be able to modify the steps of the treatment as per the requirements of the tooth anatomy. The clinician needs to stick to the endodontic protocol of precurving the file, use of irrigants and lubricants, and make sure never to work in a dry canal. In such a case, the clinician should take a pause, try not to lose patience and try their level best to open up the calcified canals. Ideally, the whole length of the root canal system should be cleaned and disinfected to the maximum limit possible.

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19 Clinical Case 19 – Management of root canal treatment failure with inadequate obturation and missed canals Viresh Chopra

Introduction to the case: case of symptomatic apical periodontitis associated with a previous inadequate root canal treatment and suspected missed canals, which could not be located at the time of initial root canal treatment.

19.1 ­Patient information ●● ●● ●●

Age: 29 years old. Gender: female. Medical history: non-contributory.

19.2 ­Tooth ●● ●●

●●

●●

●●

Identification: right maxillary first molar (Tooth 16). Dental history: chief complaint: I am having pain when I eat or put pressure on my tooth. History of previously attempted root canal treatment done on right upper maxillary first molar. The pain has existed since the root canal treatment started (approximately 2 months back). Clinical examination findings: the tooth is tender to percussion and has porcelain fused to metal bridge with support from Tooth 14. Tooth 15 is missing. Preoperative radiological assessment: the periapical radiograph revealed previously initiated root canal treatment in Tooth 16. Teeth 16 and 15 have a porcelain fused to ceramic bridge. Tooth 16 is suspected to have intracanal medicament. The palatal root is associated with periapical radiolucency (Figure 19.1). Diagnosis (pulpal and periapical): symptomatic apical periodontitis with inadequate root canal treatment.

Clinical Atlas of Retreatment in Endodontics, First Edition. Edited by Viresh Chopra. © 2021 John Wiley & Sons Ltd. Published 2021 by John Wiley & Sons Ltd. Companion website: www.wiley.com/go/chopra/retreatment

19.3 ­Treatment pla

Figure 19.1  Periapical radiograph showing inadequate root canal treatment in Tooth 16. Periapical radiolucency associated with the palatal root of 16 can be seen. Prosthesis extending from Tooth 16 to 14 is present. Suspected intracanal medicament in the palatal and distobuccal roots of Tooth 16.

19.3 ­Treatment plan The patient was informed about the problem and advised about retreatment to be done and that location of missed canals would be attempted. ●●

●●

First visit: buccal infiltration anaesthesia was administered and the tooth was isolated with rubber dam. Retreatment was initiated under microscope and access gained to the previously prepared endodontic access cavity. Palatal and mesiobuccal canals with intracanal medicament were located (Figure 19.2). The distobuccal canal was located successfully. In all, three canals, namely mesiobuccal, distobuccal and palatal, were successfully located (Figure 19.3). Once the canals were located, intracanal medicament was placed in all the canals (Videos 1 and 2), a temporary dressing was placed and the patient scheduled for the next appointment. Second visit: this appointment was planned for location of a second mesiobuccal canal (MB2), if present. In addition, final cleaning and shaping of the canal was planned. If the patient remained comfortable throughout the appointment and if time permitted obturation was also planned. An attempt to locate the MB2 canal was made with endodontic ultrasonic tips. After modifying the access cavity and excavating, the MB2 canal was located (Figure 19.4).

Figure 19.2  First look at the endodontic access cavity in Tooth 16. Intracanal medicament is present in the distobuccal and palatal canals.

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19  Clinical Case 19

Figure 19.3  Mesiobuccal, distobuccal and palatal canals successfully located. The endodontic access cavity can be seen filled with endodontic irrigant.

Figure 19.4  MB2 canal located with the help of endodontic ultrasonic tips.

Endodontic hand files were used to determine working length along with an electronic apex locator. The working length was verified with a periapical radiograph (Figure 19.5). For cleaning and shaping, HyFlexTM endodontic files from Coltene were used with copious irrigation. Tactile controlled activation (TCA) technique was used to clean and shape all the canals (Videos 3 and 4). All the canals were finally prepared up to 25/04 size (Figure  19.6). Periapical radiograph was done to verify the fit of the master cones (Figure 19.7). TotalFill®, a bioceramic sealer from FKG, was used along with gutta-percha as the core obturating material. The premixed sealer was applied in the canals with the help of disposable dispending tips (Videos 5 and 6). The master cones were coated with the sealer and placed inside the canals. Warm vertical condensation technique was used to obturate the canals. All the canals were obturated and

19.3 ­Treatment pla

Figure 19.5  Periapical radiograph verifying the working length.

Figure 19.6  All the canals prepared up to 25/04 size with HyFlex files. Figure 19.7  Periapical radiograph verifying location of master cones in all the four canals.

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19  Clinical Case 19

Figure 19.8  All the canals obturated with gutta-percha and sealer. The pulp chamber is free from any sealer or obturating material remnants.

●●

●●

the pulp chamber cleaned of any gutta-percha or sealer (Figure 19.8). An immediate postoperative radiograph was taken to verify the final obturation (Figure 19.9). Once the obturation was complete the patient was referred back to the previous dentist for completion of prosthetic work. Irrigation protocol: hand files were used with EDTA gel, rinsing with saline. –– 5.25% sodium hypochlorite throughout the cleaning and shaping procedure. Rinse with saline. –– 17% EDTA 1 mL/canal with sonic/ultrasonic activation. Rinse with saline. –– Final rinse with 5.25% sodium hypochlorite with internal heating and sonic ultrasonic activation for 20–30 seconds per canal. –– Flushing with saline between irrigants is essential, as it will stop the irrigants reacting with each other. Obturation (materials and technique): TotalFill bioceramic sealer, HyFlex CM rotary endodontic files. Figure 19.9  Immediate postoperative radiograph showing obturation of all the canals.

19.6 ­Learning objective

19.4 ­Technical aspects There are many factors by which root canal orifices or parts of root canals may be calcified. Failure to locate the canal may result in inadequate cleaning and shaping. It will also leave a canal full of necrotic debris/pulpal remnants, which will result in continuous discomfort to the patient and also failure of the root canal treatment. Endodontic ultrasonic tips and an endodontic explorer should be used to locate hidden canals. Tactile sensation and patience play a vital role in negotiating calcified canals. However, as for all endodontic cases, special care should be taken not to overuse the files, specifically with curved canals, as the files can break easily in such cases. The endodontic rotary files should be used passively. In this case, HyFlex CM rotary files were used. The files were used with the TCA technique, which includes the following steps. 1) The rotary file should be introduced without any rotation until it feels resistance inside the canal. 2) Feel the canal (tactile sensation). 3) Rotate the file for a few seconds only and allow it to proceed only 1 mm apically. 4) Take out the file, irrigate the canal, clean the file, adjust the stopper, reintroduce without rotating, and repeat. 5) Repeat these steps until working length is achieved. Copious irrigation should be maintained throughout the procedure and endodontic files should not be used in dry canals.

19.5 ­Follow-up A final follow-up radiograph could not be done as the patient was referred back to the previous dentist.

19.6 ­Learning objectives ●● ●● ●● ●● ●● ●●

●●

●●

Understand how to locate extra canals and how to excavate the pulpal floor properly. Understand the need to negotiate the full length of the canal. Understand and appreciate the anatomy/shape of the root canal system. Modify the treatment steps as per the anatomy/shape of the root canal. Understand the need to limit the overuse of endodontic files in the canals. Understand the importance of using endodontic ultrasonic tips to locate hidden canal orifices. Understand the importance of incorporating the whole root canal system in the disinfection process during retreatment. Clinically decide which instrument to usd for a particular step during an endodontic treatment or retreatment.

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19.7 ­How can this endodontic mishap be avoided? A clinician should be able to read a preoperative radiograph clearly and appreciate the presence of any calcification in the canal or pulp chamber. After reading the radiograph, the clinician should be able to modify the steps of the treatment as per the requirements of the tooth anatomy. The clinician needs to stick to the endodontic protocol of precurving the file, use of irrigants and lubricants, and make sure never to work in a dry canal. In such a case, the clinician should take a pause, try not to lose patience and try their level best to open up the calcified canals. Ideally, the whole length of the root canal system should be cleaned and disinfected to the maximum limit possible.

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20 Clinical Case 20 – Management of root canal treatment failure with inadequate obturation, unusual distal root anatomy and suspected ledge formation in a mandibular molar Eugen Buga

Introduction to the case: case of symptomatic apical periodontitis associated with a previously inadequate root canal treatment. Short obturation in all the canals and suspected unusual anatomy of the distal root of a mandibular molar. Both distal and mesial roots associated with periapical radiolucency.

20.1 ­Patient information ●● ●● ●●

Age: 31 years old. Gender: male. Medical history: non-contributory.

20.2 ­Tooth ●● ●●

●●

●●

●●

Identification: right mandibular first molar (Tooth 46). Dental history: the tooth started to be painful on biting 3–4 weeks back. Now, slight swelling is also present and there is a sense of heaviness. Clinical examination findings: the tooth is tender to percussion and the buccal vestibule is painful on palpation. There was no sign of any intraoral swelling. Periodontal probing was within normal limits. The tooth has an occlusal permanent composite restoration. Preoperative radiological assessment: the two-dimensional periapical radiograph revealed a previously treated Tooth 46  with an obturation of the root canal system remaining short of the radiographic apex in all the canals. Periapical radiolucency could be detected associated with both the distal root and the mesial root (Figure 20.1). The distal canal had a bigger radiolucency and suspected unusual anatomy in the apical third. Diagnosis (pulpal and periapical): symptomatic apical periodontitis with chronic apical abscess and root canal failure due to short obturation.

Clinical Atlas of Retreatment in Endodontics, First Edition. Edited by Viresh Chopra. © 2021 John Wiley & Sons Ltd. Published 2021 by John Wiley & Sons Ltd. Companion website: www.wiley.com/go/chopra/retreatment

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Figure 20.1  Periapical radiograph showing previously treated Tooth 46 with an obturation of the root canal system remaining short of the radiographic apex. Periapical radiolucency can be detected on the radiograph associated with the distal and mesial roots. Unusual root canal anatomy suspected in the apical part of the distal root.

20.3 ­Treatment plan ●●

●●

Preliminary procedures: local anaesthesia was administered and the tooth was isolated with rubber dam. The tooth was visualized under the dental operating microscope (Figure 20.2). The endodontic access cavity was prepared through the resin composite permanent restoration. Management of the endodontic mishap: the endodontic access cavity was prepared and older gutta-perchas located. The gutta-perchas were traced and the design of the endodontic access cavity was assessed (Figure  20.3). The previous obturating material was removed using endodontic rotary retreatment files D1, D2 and D3 from Dentsply (Figure 20.4). Once Figure 20.2  Rubber dam isolation of the tooth.

20.3 ­Treatment pla

Figure 20.3  Previous gutta-percha located and endodontic access cavity assessed for any modification.

Figure 20.4  Removal of previous obturating material with endodontic retreatment rotary files.

●●

the older gutta-percha was removed from all the canals, the pulpal floor was examined for presence of any extra canals, particularly the distal canal area due to suspected unusual anatomy (Figure 20.5).   On careful exploration of the pulpal floor, an extra orifice was found next to the previous distal canal orifice (Figure 20.6). The suspected extra canal orifice was further explored with endodontic 08 K and 10 K hand files. The presence of an extra canal was clinically confirmed by negotiating the whole length of the canal with 08 K and 10 K files initially (Figure 20.7). The clinical observation was also confirmed radiographically. The working length was determined with the help of endodontic hand files and an electronic apex locator (Figure 20.8). Endodontic mishap repair procedure: after removal of older gutta-perchas, careful exploration of the pulpal floor was carried out in order to determine the presence of any missed canals. After finding an extra orifice, a precurved 10 K file was used to negotiate the acute apical curvature of the distal canal. The object of precurving is to find the path of the main canal with the help of a

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Figure 20.5  Clinical picture showing the distal canals and the pulpal floor during exploration for extra canals.

Figure 20.6  Extra canal orifice suspected next to previous distal canal orifices.

Figure 20.7  Suspected extra canal orifice negotiated and an extra canal located in the distal aspect of the pulp chamber.

20.4 ­Technical aspect

Figure 20.8  The periapical radiograph verifying the complete removal of gutta-perchas and the working length. The apical curvatures can be seen negotiated in both mesial and distal canals (inset: preoperative radiograph for reference).

●●

●●

●● ●●

watch winding motion. Copious irrigation was used during the whole procedure to reduce the risk of fracture due to friction. The same protocol was followed for mesial canals as they also had apical curvatures. Canal preparation (or retreatment procedure): the root canals were cleaned and shaped with endodontic hand files to 20 K and then rotary files were introduced. A HyFlex® CM file from Coltene was used for cleaning and shaping. The final preparation was kept at 25/04  in all the canals. Irrigation (solution and technique): disinfection was achieved with positive syringe irrigation of 5% NaOCl. EDTA gel, saline, 5% sodium hypochlorite, saline and EDTA liquid were used as endodontic irrigants alternately. –– 5% NaOCl; passive ultrasonic irrigation (3 × 20 seconds). Final irrigation protocol: 17% EDTA (syringe irrigation) for 3 minutes. Obturation (material and technique): epoxy resin-based sealer (AH Plus®) was used along with gutta-percha as the core obturating material. The technique used was warm vertical compaction and the obturation was verified on the radiograph (Figure 20.9).

20.4 ­Technical aspects Preoperative radiographs are of great importance in clinical practice. Periapical radiographs are two-dimensional, however, so failure to read the preoperative radiograph properly can lead to inadequately treated cases. Failure to negotiate the full length of the root canal system during the

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Figure 20.9  The immediate postoperative periapical radiograph verifying the obturation of all the canals up to the full working length.

endodontic process might result in inadequate cleaning and shaping, leading to persistence of the disease. Precurved files should be used to achieve canal patency in curved canals. Along with precurved files, copious irrigation is required with every instrument to allow the instrument to slide inside the canal and reduce frictional forces. As for all endodontic cases, however, special care should be taken not to overuse the files, particularly with curved canals. as the files can break easily in such cases. The cleaning and shaping procedure during retreatment should address the whole root canal system.

20.5 ­Follow-up The 6-month follow-up clinical and radiographic examination revealed an asymptomatic tooth and ongoing healing of the periapical lesion, especially in the distal root (Figure 20.10).

20.6 ­Learning objectives ­The reader should understand: the need to read the preoperative radiograph properly ●● the limitations of a two-dimensional radiograph ●● the anatomy/shape of the root canal system ●● the need to plan/modify the treatment steps as per the anatomy of the root canal ●● the need to verify the endodontic access cavity before proceeding to the next step ●● the need to use magnification. ●●

20.7  ­How can this endodontic

mishap be avoided

Figure 20.10  The 6-month recall periapical radiograph verifying the intact obturation of all canals up to the full working length. Also, ongoing healing of the distal lesion can be seen.

●● ●● ●●

the importance of precurving initial instruments to gain canal patency the importance of hand filing before introducing rotary files inside the root canals the importance of incorporating the whole root canal system in the disinfection process during retreatment.

20.7 ­How can this endodontic mishap be avoided? A clinician should be able to read the preoperative radiograph correctly and appreciate the presence of curvatures, extra canals or roots shown in the radiograph. After reading the radiograph, clinician should be able to modify the steps of the treatment as per the requirement of the tooth anatomy. Sometimes, the radiograph might not show the complete picture, in which case the clinician should take a pause, have a good look under magnification and confirm the direction of protocol. The whole length of the root canal system should be cleaned and disinfected to the maximum limit possible.

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21 Clinical Case 21 – Management of root canal treatment failure with inadequate obturation and faulty post placement Viresh Chopra

Introduction to the case: case of failed root canal treatment associated with a previous inadequate root canal treatment and faulty placement. The patient reported with symptomatic apical periodontitis.

21.1 ­Patient information ●● ●● ●●

Age: 28 years old. Gender: male. Medical history: non-contributory.

21.2 ­Tooth ●● ●●

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●●

●●

Identification: right mandibular first molar (Tooth 46). Dental history: chief complaint: I am having pain when I eat or put pressure on my tooth. History of previously attempted root canal treatment done on right mandibular first molar. Root canal was done 2 years back. Clinical examination findings: the tooth is tender to percussion and has a resin composite restoration, and occlusally the metallic post is visible. Preoperative radiological assessment: the periapical radiograph revealed previous root canal treatment in Tooth 46. The tooth had a metallic screw/threaded post in the distal canal (Figure 21.1). Diagnosis (pulpal and periapical): symptomatic apical periodontitis with inadequate root canal treatment. The patient was informed about the problem and advised retreatment in 46. Patient advised about post removal to be done, presence of cracks to be explored and retreatment to be done along with location of missed canals will be attempted.

Clinical Atlas of Retreatment in Endodontics, First Edition. Edited by Viresh Chopra. © 2021 John Wiley & Sons Ltd. Published 2021 by John Wiley & Sons Ltd. Companion website: www.wiley.com/go/chopra/retreatment

21.3 ­Treatment pla

Figure 21.1  Periapical radiograph showing inadequate root canal treatment in Tooth 46. Periapical radiolucency associated with the mesial roots can be seen. A metallic threaded post can be seen in the distal canal.

21.3 ­Treatment plan The patient was advised about post removal to be done, presence of cracks to be explored and retreatment to be done along with location of missed canals. ●●

●●

First visit: buccal infiltration anaesthesia was administered and the tooth was isolated with rubber dam. The retreatment was initiated under microscope. The occlusal surface showed resin composite restoration along with a metallic post head (Figure 21.2). The first step was to remove the resin composite restoration and expose the occlusal part of the metallic post (Figure  21.3). Once the occlusal part of the post was exposed, endodontic ultrasonic tips were used to unscrew/loosen the post and facilitate its removal from the canal (Figure 21.4) (Video 1). The post was loosened with the help of ultrasonic tips and removed from the canal (Figure 21.5). Second visit: removal of gutta-percha from the pulp chamber and the canals was carried out in the second appointment. Also, the access cavity was explored for presence of any cracks or extra canals. Removal of previous gutta-percha from the canals was carried out using the XP-endo® Shaper file from FKG. The gutta-percha was first softened with the use of gutta-percha solvent

Figure 21.2  Rubber dam isolation of Tooth 46. Occlusal surface with resin composite and head of the metallic threaded post.

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(a)

(b)

Figure 21.3  (a,b) Removal of the resin composite restoration to expose the head and the occlusal part of the metallic post. Figure 21.4  Post removal with the help of endodontic ultrasonic tips.

(a)

(b)

Figure 21.5  (a) The distal canal after removal of the metallic post. (b) Metallic post after removal.

21.3 ­Treatment pla

(a)

(b)

Figure 21.6  (a) Gutta-percha removed from the pulp chamber. (b) Gutta-percha removed from the canals.

and then the XP-endo Shaper file was introduced at 2500 rpm to facilitate the removal of guttapercha from the canal (Video 2) (Figure 21.6).   In addition to the removal of gutta-perchas, final cleaning and shaping of the canal was carried in this visit. If the patient remained comfortable throughout the appointment and if time allowed, obturation was also planned in the same appointment. Once the removal of guttaperchas was completed, the access cavity was explored for presence of cracks and extra canals. No extra canals were found. Endodontic hand files were used to determine working length along with an electronic apex locator. The working length was verified with a periapical radiograph (Figure 21.7).   The canals were finally cleaned and shaped with HyFlex® CM files up to size 25/04. EDTA gel, saline, 2.5% sodium hypochlorite and EDTA liquid were used as irrigants alternately (Figure 21.8). Ultrasonic activation of the irrigants was done with EndoUltra® from Dentsply (Video 3). Figure 21.7  Periapical radiograph showing working length determination after gutta-percha removal.

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Figure 21.8  Clinical picture showing irrigant inside the canals and pulp chamber.

●●

  Clinically, the fit of the master cones was verified with a periapical radiograph at the calculated working length (Figure 21.9) (Video 4).   TotalFill®, a bioceramic sealer from FKG, was used along with gutta-percha as the core obturating material. The premixed sealer was applied in the canals with the help of disposable dispensing tips (Video 5). The master cones were coated with the sealer and placed inside the canals (Video 6). The gutta-percha was cut at the orifice level with a System B Plugger (Video 7). All the canals were obturated and the pulp chamber cleaned of any gutta-percha or sealer (Figure 21.10). An immediate postoperative radiograph was taken to verify the final obturation (Figure 21.11). Irrigation protocol: hand files were used with EDTA gel, rinsing with saline. –– 2.5% sodium hypochlorite throughout the cleaning and shaping procedure. Rinse with saline. –– 17% EDTA 1 mL/canal with sonic/ultrasonic activation. Rinse with saline. –– Final rinse with 2.5% sodium hypochlorite with internal heating and sonic ultrasonic activation for 20–30 seconds per canal. –– Flushing with saline between irrigants is essential, as it will stop the irrigants reacting with each other.

●●

Obturation (materials and technique): TotalFill bioceramic sealer, HyFlex CM rotary endodontic files. Figure 21.9  Periapical radiograph to verify the fit of the master cones at the correct working length.

21.4 ­Technical aspect

Figure 21.10  Immediate clinical picture showing obturation of all the canals up to the canal orifice.

Figure 21.11  Immediate postobturation periapical radiograph confirming the obturation of all the canals up to the calculated working length.

21.4 ­Technical aspects Proper cleaning and shaping of the root canals along with adequate disinfection is one of the important requirements for the success of endodontic treatment. Failure to achieve adequate disinfection through irrigation will result in overlooked microorganisms or pulpal debris leading to post-treatment infections. Endodontic ultrasonic tips should be used to stay conservative while removing metallic posts or broken files from the root canals. Excessive removal of tooth structure might lead to fracture of the tooth due to low strength. If a post has to be placed inside the root canal then it should have adequate length to be stable as retention of the post inside the canal is directly proportional to the length of the post in the canal. In this case, HyFlex CM rotary files were used. The files were used with TCA technique which includes the following steps. 1) The rotary file should be introduced without any rotation until it encounters resistance inside the canal. 2) Feel the canal (tactile sensation).

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3) Rotate the file for a few seconds only and allow it to proceed only 1 mm apically. 4) Take out the file, irrigate the canal, clean the file, adjust the stopper, reintroduce without rotating, and repeat. 5) Repeat these steps until working length is achieved. Copious irrigation should be maintained throughout the procedure and endodontic files should not be used in dry canals.

21.5 ­Follow-up A follow-up radiograph could not be done as the patient did not return after treatment.

21.6 ­Learning objectives ●●

●● ●● ●● ●● ●● ●●

●●

Understand the importance of using endodontic ultrasonic tips for removal of metallic posts from the root canals. Understand the need to negotiate the full length of the canal. Understand and appreciate the anatomy/shape of the root canal system. Modify the treatment steps as per the anatomy/shape of the root canal. Understand the role of irrigants for disinfecting the root canal system. Understand the importance of using endodontic ultrasonic tips to locate hidden canal orifices. Understand the importance of incorporating the whole root canal system in the disinfection process during retreatment. Clinically decide which instrument should be used for a particular step during an endodontic treatment or retreatment.

21.7 ­How can this endodontic mishap be avoided? Proper cleaning and shaping along with adequate use of irrigants for disinfection are necessary for the success of endodontic treatment. Failure to achieve the required disinfection might lead to post-treatment disease, thus causing failure of the endodontic treatment.

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22 Clinical Case 22 – Management of root canal treatment failure with inadequate obturation, multiple perforations, fractured instrument and ledge formation in maxillary right first molar Viresh Chopra

Introduction to the case: case of upper right maxillary first molar with failed root canal treatment, periradicular radiolucency, furcal radiolucency, fractured instrument and ledge formation. Radiographically, suspected to have pulpal floor perforation.

22.1 ­Patient information ●● ●● ●●

Age: 37 years old. Gender: male. Medical history: non-contributory.

22.2 ­Tooth ●● ●●

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●●

●●

Identification: right maxillary first molar (Tooth 46). Dental history: patient reported with a chief complaint of intraoral swelling with tenderness on biting. In addition, complaints of bad taste occasionally. Clinical examination findings: the tooth was tender to percussion and had a resin composite restoration. The buccal vestibule had intraoral swelling associated with a draining sinus. Preoperative radiological assessment: the periapical radiograph revealed previous root canal treatment in Tooth 16. The following are the observations after reading the preoperative radiograph (Figure 22.1). –– Furcal periradicular radiolucency. –– Short obturation in all the canals. –– Periapical radiolucent around DB root. –– Suspected ledge formation in DB root. –– Suspected fractured instrument in the apical part of the MB root. Diagnosis (pulpal and periapical): symptomatic apical periodontitis with inadequate root canal treatment.

Clinical Atlas of Retreatment in Endodontics, First Edition. Edited by Viresh Chopra. © 2021 John Wiley & Sons Ltd. Published 2021 by John Wiley & Sons Ltd. Companion website: www.wiley.com/go/chopra/retreatment

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Figure 22.1  Periapical radiograph showing inadequate root canal treatment in Tooth 16. Periapical radiolucency associated with furcation and the mesiobuccal root can be seen. The fractured instrument in the distobuccal root can be seen. Short obturations are noticeable in the MB canal.

­22.3  Treatment plan Retreatment of Tooth 16 was advised and the patient was informed about the poor prognosis of the tooth and that it might have to be extracted if it did not respond to the treatment. Informed consent was taken from the patient.

The treatment was planned in different stages. Stage 1 ●● ●● ●● ●●

Gain entry in the pulp chamber and locate orifices. Look for any perforations. Seal any perforations present. Removal of gutta-percha from the canals.

Stage 2 ●● ●● ●●

Remove ledge and negotiate the rest of the canal. Clean and shape the canals (not retrieving the instrument but an attempt to bypass will be done). Placement of intracanal medicament.

Stage 3 ●● ●● ●●

Obturation. Recall. First visit: buccal infiltration anaesthesia was administered and the tooth was isolated with rubber dam. The retreatment was initiated under microscope. The occlusal surface showed the resin composite restoration along with metallic post head (Figure 22.2).

The first step was to remove the resin composite restoration and locate the previous guttaperchas which will guide us to the orifices (Figure 22.3). Endodontic ultrasonic tips were used to gain entry into the pulp chamber and while locating previous gutta-perchas, signs of perforation in the central part and palatal aspect were seen (Figure 22.4) (Video 1). It was decided to remove the gutta-perchas from the canals, access the perforation site and repair it in the same sitting.

­22.  Treatment plan

Figure 22.2  Rubber dam isolation of Tooth 16. Occlusal surface with resin composite restoration.

(a)

(b)

Figure 22.3  (a) Initiation of endodontic access cavity. (b) First sight of previous gutta-perchas.

Figure 22.4  Signs of bleeding (perforation of the pulpal floor) can be seen while gaining re-entry into the pulp chamber for retreatment.

The access cavity was prepared to achieve straight-line access to the canals. Adequate care was taken not to widen the pulpal floor perforation. Once the orifices were located, gutta-perchas were removed from the canals, taking care not to touch the perforation site (Figure 22.5). Once complete removal of gutta-percha was done and verified on the radiograph (Figure  22.6), intracanal medicament was placed inside the canals and preparation for perforation repair was carried out (Figure 22.7). The orifices of the canals were temporarily blocked with gutta-percha, the perforations were dried and MTA mixed as per the manufacturer’s instructions. MTA was placed in increments

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Figure 22.5  Removal of gutta-perchas from inside the canals, taking care not to disturb the perforation site.

Figure 22.6  Periapical radiograph to confirm the complete removal of gutta-perchas from inside the canals. The fractured instrument is visible in the DB root and it has been decided to leave it there.

Figure 22.7  Intracanal medicament placed in the canals. Perforation clearly visible. Perforation site dried for repair with MTA.

(Video 2) in the perforation sites, namely the centre of the access cavity (Figure 22.8) and the palatal perforation (Figure 22.9). MTA was placed and condensed to seal the perforations (Figure 22.10) (Video 3). The patient was recalled for the next appointment for working length determination and completion of root canal treatment. ●● Second visit: the further steps of endodontic retreatment were carried out after accessing the MTA placed to seal the perforation site in the previous visit. Clinically, the intraoral swelling and

­22.  Treatment plan

Figure 22.8  MTA placed over the perforation site.

Figure 22.9  Clinical picture showing dry palatal perforation, after sealing the central perforation with MTA.

Figure 22.10  Clinical picture showing sealing of both the perforation sites with MTA.

draining sinus had subsided. The patient also felt relief on biting the tooth. The body tissues could be seen responding positively to the treatment protocol. However, on removal of the temporary filling, the MTA in the central perforation had set well but the MTA placed in the palatal perforation had dislodged completely and the site exhibited blood (Figure 22.11). The palatal perforation was dried and placement of MTA was repeated in order to seal the perforation. A microbrush was used to condense the MTA and hydrate it in order to facilitate faster setting (Figure 22.12) (Video 4). After placing the MTA, working length was determined using an electronic apex locator and verified on a radiograph (Figure 22.13).

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Figure 22.11  Clinical picture showing set MTA on the central perforation whereas the MTA placed on the palatal perforation had dislodged.

Figure 22.12  Clinical picture showing use of a microbrush to condense the MTA and hydrate it to facilitate faster setting.

Figure 22.13  Working length radiograph.

Removal of previous gutta-percha from the canals was done using an XP-endo® Shaper file from FKG. The gutta-percha was first softened with gutta-percha solvent and then the XP-endo Shaper file was introduced at 2500 rpm to facilitate removal of gutta-percha from the canal. The decision was made not to attempt removal of the fractured instrument but to bypass it in the distobuccal canal. However, as bypassing the instrument was not successful, the distobuccal canal was cleaned up to the fractured instrument.

­22.  Treatment plan

The mesiobuccal canal had a ledge in the apical area. A 10  K file was precurved in order to attempt bypass of the ledge. Once the ledge was bypassed, the wall of the canal was filed in order to remove the ledge and facilitate cleaning the whole length of the canal. Once the full working length was achieved, the canals were finally cleaned and shaped with HyFlex® CM files up to size 25/04. EDTA gel, saline, 2.5% sodium hypochlorite and EDTA liquid were used as irrigants alternately. Ultrasonic agitation of the irrigants was done with the EndoUltra® ultrasonic activator from Dentsply. Clinically, the fit of the master cones was checked and verified with a periapical radiograph at the calculated working length (Figure 22.14). Once the master cone fit was confirmed, the canal orifices were temporarily blocked with gutta-percha and glass ionomer cement was placed to cover the entire pulpal floor (Figure 22.15). Glass ionomer cement was used to secure the MTA in place as it had dislodged in the previous visit. AH Plus® was used as a root canal sealer along with gutta-percha as the core obturating material. The sealer was applied inside the canals (Figure  22.16) and the master cones were coated with the sealer and placed inside the canals (Figure 22.17). The gutta-percha was cut at the orifice level with a System B Plugger. All the canals were obturated with warm vertical condensation technique and the pulp chamber cleaned of any gutta-percha or sealer Figure 22.14  Radiograph to verify the fit of the master cones.

Figure 22.15  Clinical picture showing blocking of canals with gutta-percha and placement of glass ionomer cement on the pulpal floor.

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Figure 22.16  Clinical picture showing sealer inside the mesiobuccal canal.

Figure 22.17  Clinical picture showing placement of gutta-perchas inside the canals.

(Figure 22.18). An immediate postoperative radiograph was taken to verify the final obturation (Figure 22.19). ●●

●●

Irrigation protocol: hand files were used with EDTA gel, rinsing with saline. –– 2.5% sodium hypochlorite throughout the cleaning and shaping procedure. Rinse with saline. –– 17% EDTA 1 mL/canal with sonic/ultrasonic activation. Rinse with saline. –– Final rinse with 2.5% sodium hypochlorite with internal heating and sonic ultrasonic activation for 20–30 seconds per canal. –– Flushing with saline between irrigants is essential, as it will stop the irrigants reacting with each other. Obturation (materials and technique): AH Plus root canal sealer, HyFlex CM rotary endodontic files.

22.4 ­Technical aspects Endodontic mishaps can interfere with the healing process of the body and can result in failure of the root canal treatment if not dealt with. Perforation, if present, should be handled immediately and adequate materials used for better results. Fracture of an instrument results in improper cleaning and shaping of the part of the canal beyond the instrument. Proper cleaning and shaping of the root canals along with adequate disinfection is a vital requirement for the success of endodontic treatment. Ledge formation results in loss of working length. If not

22.4 ­Technical aspect

Figure 22.18  Clinical picture showing obturation of the canals.

Figure 22.19  Immediate postoperative radiograph showing obturation and MTA in the furcation area.

bypassed, it also leaves the part of the canal beyond the ledge uncleaned which can result in failure of the treatment carried out. Endodontic ultrasonic tips should be used to stay conservative while cutting tooth structure around perforations. Excessive removal of tooth structure might lead to fracture of the tooth due to low strength. Care has to be taken not to disturb the perforation with instruments and cause bleeding. In this case, HyFlex CM rotary files were used. The files were used with TCA technique which includes the following steps. 1) The rotary file should be introduced without any rotation until it encounters resistance inside the canal. 2) Feel the canal (tactile sensation). 3) Rotate the file for a few seconds only and allow it to proceed only 1 mm apically. 4) Take out the file, irrigate the canal, clean the file, adjust the stopper, reintroduce without rotating, and repeat. 5) Repeat these steps until working length is achieved. Copious irrigation should be maintained throughout the procedure and endodontic files should not be used in dry canals.

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Figure 22.20  Six-month recall radiograph showing adequate healing of the periradicular area and the furcation area.

­22.5  Follow-up A 6-month follow up radiograph shows significant healing of the periradicular area (Figure 22.20).

­22.6  Learning objectives The reader should be able to understand: ●● ●●

●●

●●

●● ●●

●●

●●

●● ●●

the significance of proper reading of the preoperative radiograph the importance of using endodontic ultrasonic tips to gain reentry to the pulp chamber for retreatment the reasons for creation of a ledge and the need to bypass the ledge and negotiate the full length of the canal the need to plan/modify the treatment steps as per the clinical findings during the procedure (in this case, the moment perforations were found, the appointment was modified for perforation repair) the role of irrigants in disinfecting the root canal system the importance of decision making for bypassing, removing or leaving the fractured instrument in the canal the importance of incorporating the whole root canal system in the disinfection process during retreatment how to decide which instrument should be used for a particular step during endodontic treatment or retreatment the importance of using the right materials to initiate healing the concepts of the prognosis of the tooth and trying to save the tooth instead of immediately extracting it.

22.7  ­How can this endodontic

mishap be avoided

22.7 ­How can this endodontic mishap be avoided? This case included the following endodontic mishaps. ●●

●●

●●

Pulpal floor perforations: these can be avoided as follows. –– On a preoperative radiograph, measure the depth of the bur that needs to be inserted inside the pulp chamber. –– Keep checking while cutting the access cavity with the bur. –– Use non-end cutting burs for the access cavity. –– Use magnification for endodontics. –– Use endodontic ultrasonic tips to stay conservative. Fractured instrument: this can be avoided as follows. –– Always use instruments with lubrication. –– Never instrument in a dry canal. –– Precurve smaller instruments and use with lubrication. –– Use a lot of irrigation. –– Do not use force for cleaning and shaping. –– Achieve a glide path and then proceed. –– Use instruments in the correct sequence. Ledge formations: these can be avoided as follows. –– Using precurved files for instrumentation. –– Use of lubrication and irrigation during cleaning and shaping. –– Using the endodontic files in the correct sequence. –– Maintaining patience during cleaning and shaping. Do not hurry.

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23 Clinical Case 23 – Management of root canal treatment failure with inadequate obturation, fractured instrument and periapical lesion in mandibular left first molar Viresh Chopra

Introduction to the case: case of left mandibular first molar with failed root canal treatment, periradicular radiolucency, fractured instrument and missed canal.

23.1 ­Patient information ●● ●● ●●

Age: 13 years old. Gender: male. Medical history: non-contributory.

2 ­ 3.2  Tooth ●● ●●

●●

●●

●●

Identification: left mandibular first molar (Tooth 36). Dental history: patient reported with a chief complaint of intraoral swelling with tenderness on biting. In addition, complaints of bad taste occasionally. Clinical examination findings: the tooth was tender to percussion and had a porcelain fused to metal crown. The buccal vestibule had intraoral swelling associated with draining sinus. Preoperative radiological assessment: the periapical radiograph revealed previous root canal treatment in Tooth 36. The following are the observations after reading the preoperative radiograph (Figure 23.1). –– Short obturation in the canals with inadequate condensation. –– Periapical radiolucency around the MB root. –– Suspected fractured instrument in the apical part of the MB root. Diagnosis (pulpal and periapical): symptomatic apical periodontitis with apical abscess and inadequate root canal treatment.

2 ­ 3.3  Treatment plan Retreatment of Tooth 36 was advised and the patient was informed about the poor prognosis of the tooth and that the tooth might have to be extracted if did not respond to the treatment. The patient was also informed about the fractured instrument and was made aware that while removing gutta-perchas, Clinical Atlas of Retreatment in Endodontics, First Edition. Edited by Viresh Chopra. © 2021 John Wiley & Sons Ltd. Published 2021 by John Wiley & Sons Ltd. Companion website: www.wiley.com/go/chopra/retreatment

­23.  Treatment plan

Figure 23.1  Periapical radiograph showing inadequate root canal treatment in Tooth 36. Periapical radiolucency associated with the mesiobuccal root can be seen. Fractured instrument in the distobuccal root can be seen as well. Short obturations are noticeable in the MB canal.

the instrument might come out or even slip beyond, as the apices are wide open. If the instrument slipped into the periapical region, we would finish the root canal and wait for the response. If there was healing, the instrument would be left there but if the patient remained symptomatic then a surgical option would be considered. The patient agreed and informed consent was taken from him. The treatment was planned in different stages. Stage 1 ●● ●● ●● ●●

Gain entry in the pulp chamber and locate orifices. Look for any perforations. Seal any perforations present. Removal of gutta-percha from the canals.

Stage 2 ●● ●● ●●

Exploration of the access cavity to locate missed canals. Complete removal of gutta-perchas. Placement of intracanal medicament.

Stage 3 ●● ●● ●●

Clean and shape the canals. Obturation. Recall.

First visit: buccal infiltration anaesthesia was administered and the tooth was isolated with rubber dam. The retreatment was initiated under microscope. The PFM crown was removed and entry into the pulp camber initiated (Figure 23.2a). The first step was to remove the resin composite restoration and locate the previous gutta-perchas which would guide us to the orifices (Figure 23.2b). Endodontic ultrasonic tips were used to gain entry into the pulp chamber and the previous gutta-perchas located. The access cavity was prepared to achieve straight-line access to the canals. Adequate care was taken not to widen the access cavity (Figure 23.3). Once the orifices were located, gutta-perchas were removed from the canals, taking care not to disturb the fractured instrument (Figure 23.4). Once complete removal of gutta-perchas was achieved, a radiograph was taken to verify the

●●

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(a)

(b)

Figure 23.2  (a) Removal of PFM crown and rubber dam isolation of Tooth 36. (b) Gaining access into the pulp chamber and locating older gutta-perchas. Figure 23.3  The access cavity design and the previous gutta-perchas.

Figure 23.4  Removal of previous gutta-percha from the canals.

position of the instrument (Figure 23.5). The instrument had slipped beyond the apical foramen. The patient was informed of this and the decision was made to leave the instrument as it was. Intracanal medicament was placed inside the canals and the patient recalled for cleaning and shaping (Video 1). ●● Second visit: the second appointment was planned to continue with the further steps of endodontic retreatment of cleaning and shaping of the root canal system. Clinically, the intraoral swelling and draining sinus had subsided. The patient also felt relief on biting the tooth. The body tissues could be seen responding positively to the treatment protocol. However, exploration of

­23.  Treatment plan

Figure 23.5  Periapical radiograph to confirm removal of gutta-perchas from inside the canals. The instrument had slipped beyond the apical foramen.

the access cavity needs to be done whenever starting with cleaning and shaping, particularly in cases of retreatment. The access cavity was explored and an extra mesial canal was found (Figure 23.6). The main challenge was to retrieve the previous gutta-perchas from the mesial canals as they were within the walls of the canals (Figure  23.7). Removal of previous gutta-percha from the mesial canals was carried out with an XP-endo® Shaper file from FKG. The gutta-percha was first Figure 23.6  Middle mesial canal found after exploration of the access cavity.

Figure 23.7  Previous gutta-perchas stuck in the mesial canals.

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Figure 23.8  Stuck gutta-perchas removed from the mesial canals with the XP-endo Shaper file.

softened with gutta-percha solvent and then the file was introduced at 2500 rpm to facilitate removal of gutta-percha from the canal (Video 2) (Figure 23.8). Once the gutta-perchas were completely removed, intracanal medicament was again placed and the patient scheduled for a third visit. ●● Third visit: once the full working length was achieved, the mesial canals were finally cleaned and shaped with HyFlex® CM files up to size 25/04. EDTA gel, saline, 2.5% sodium hypochlorite and EDTA liquid were used as irrigants alternately. Irrigation was done with disposable and flexible Irriflex® needles from Produits Dentaires (Video 3). Ultrasonic agitation of the irrigants was done with the EndoUltra® ultrasonic activator from Dentsply. While cleaning and shaping the distal canal, it was realized that the apical foramen was wide and achieving an apical seal with gutta-percha alone might not serve the purpose. The decision was made to place MTA in the apical part and then backfill with thermoplasticized gutta-percha. Because of their width, the distal canals were cleaned with the XP-endo Shaper file and irrigated with Irriflex needles (Video 4). Once the canals were cleaned and shaped, the master cone fit in the mesial canals was confirmed and the mesial canal orifices were temporarily blocked with gutta-percha so that MTA did not fall into the canals. The MTA was mixed as per the manufacturer’s instructions and placed inside the distal canal with the help of an MTA gun (Videos 5 and 6). The MTA was condensed using a System B Plugger and paper points (Video 7). The placement of MTA up to the apical foramen and master cone fit in the mesial canals were confirmed with a radiograph (Figure 23.9). The fractured instrument can be seen in the periapical area. Figure 23.9  Placement of MTA in the distal canal and master cone fit in the mesial canals verified with a radiograph.

­23.  Treatment plan

The mesial canals were obturated with a single cone obturation technique using AH Plus® as root canal sealer. The gutta-perchas were cut at the orifice with a heated plugger (Video 8). The distal canal was backfilled with thermoplasticized gutta-percha from Obtura (Video 9). The obturation was confirmed with a radiograph (Figure 23.10). The patient was referred to the pedodontist for placement of a prefabricated stainless steel crown (Figure 23.11). ●●

Irrigation protocol: hand files were used with EDTA gel, rinsing with saline. –– 2.5% sodium hypochlorite throughout the cleaning and shaping procedure. Rinse with saline. –– 17% EDTA 1 mL/canal with sonic/ultrasonic activation. Rinse with saline. –– Final rinse with 2.5% sodium hypochlorite with internal heating and sonic ultrasonic activation for 20–30 seconds per canal. –– Flushing with saline between irrigants is essential, as it will stop the irrigants reacting with each other.

Figure 23.10  Radiograph verifying obturation of Tooth 36 up to the calculated working length.

Figure 23.11  Radiograph verifying the fit of the prefabricated stainless steel crown.

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●●

Disposable Irriflex needles were used for irrigation. They offer the following advantages. –– They are made of plastic and are transparent. –– They are double side vented. –– They are flexible and can take the shape of the canal to some extent. Obturation (materials and technique): AH Plus root canal sealer, single cone gutta-perchas, HyFlex CM rotary endodontic files for cleaning and shaping, XP-endo Shaper for removal of previous gutta-perchas and cleaning of wide distal canal.

23.4 ­Technical aspects Endodontic mishaps can interfere with the healing process of the body and can result in failure of the root canal treatment if not taken care of. Fracture of an instrument does not allow proper cleaning and shaping of the canal beyond the point of fracture. Therefore, the part of the canal beyond the fractured instrument acts as a reservoir for microorganisms to multiply and cause infection and results in failure of root canal treatment. Cleaning and shaping of the root canals along with adequate disinfection is an essential requirement for the success of endodontic treatment. Improper condensation of the obturating material leads to spaces in between which serve as channels for microleakage. In this case, HyFlex CM rotary files were used for cleaning and shaping of the mesial canals. The files were used with TCA technique which includes the following steps. 1) The rotary file should be introduced without any rotation until it encounters resistance inside the canal. 2) Feel the canal (tactile sensation). 3) Rotate the file for a few seconds only and allow it to proceed only 1 mm apically. 4) Take out the file, irrigate the canal, clean the file, adjust the stopper, reintroduce without rotating, and repeat. 5) Repeat these steps until working length is achieved. Copious irrigation should be maintained throughout the procedure and endodontic files should not be used in dry canals.

23.5 ­Follow-up A 6-month follow-up radiograph shows significant healing of the periradicular area (Figure 23.12).

23.6 ­Learning objectives The reader should be able to understand: ●● ●● ●● ●●

the significance of proper reading of the preoperative radiograph the importance of knowing the challenges which will arise while carrying out the treatment the reasons for fracture of the instrument the need to plan/modify the treatment steps as per the clinical findings during the procedure (in this case, the moment the distal canal was identified as wide, placement of MTA was decided)

23.7  ­How can this endodontic

mishap be avoided

Figure 23.12  A 6-month recall radiograph showing healing of the periapical lesions. The fractured instrument can also be seen lying in the periradicular area.

●● ●●

●●

●●

●● ●●

the role of irrigants in disinfecting the root canal system the importance of decision making for removing or leaving the fractured instrument in the canal or in this case periapical area the importance of incorporating the whole root canal system in the disinfection process during retreatment how to decide which instrument should be used for a particular step during an endodontic treatment or retreatment the importance of using the right materials to initiate healing the concepts of the prognosis of the tooth and trying to save the tooth instead of immediately extracting it.

23.7 ­How can this endodontic mishap be avoided? This case included the following endodontic mishaps. ●●

●●

Fractured instrument: this can be avoided as follows. –– Always use instruments with lubrication. –– Never instrument in a dry canal. –– Precurve smaller instruments and use with lubrication. –– Use a lot of irrigation. –– Do not use force for cleaning and shaping. –– Achieve a glide path and then proceed. –– Use instruments in the correct sequence. Inadequate condensation of the obturating material: this can be avoided as follows. –– Using proper hand/finger plugger for condensation. –– Use of required condensation force.

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24 Clinical Case 24 – Retreatment of Tooth 21 Garima Poddar

Introduction to the case: a case of endodontic retreatment of a tooth with underobturation resulting in periapical radiolucency and symptoms of pain.

24.1 ­Patient information ●● ●● ●●

Age: 27 years old. Gender: female Medical history: non-contributory.

24.2 ­Tooth ●● ●●

●●

●●

●●

Identification: maxillary left central incisor (Tooth 21). Dental history: patient complained of pain in the maxillary left anterior region for 1.5 months. She also gave a history of an old RCT performed around 9 years back. The pain was dull, aching and continuous in nature and was relieved with analgesics. Clinical examination findings: on clinical examination, the tooth was seen to be discoloured and was tender to percussion (Figures 24.1 and 24.2). Preoperative radiological assessment (Figure 24.3): on intraoral periapical radiograph, the tooth showed the following: –– underobturated canal (about 1 mm short obturation) –– periapical radiolucency associated with Tooth 21 which did not have a defined margin. Diagnosis: pulpal – previously treated; periapical – symptomatic apical periodontitis.

24.3 ­Treatment plan ●●

Preliminary procedures –– Local anaesthesia: 2% lignocaine with adrenaline injection was infiltrated buccally using a 30 gauge needle.

Clinical Atlas of Retreatment in Endodontics, First Edition. Edited by Viresh Chopra. © 2021 John Wiley & Sons Ltd. Published 2021 by John Wiley & Sons Ltd. Companion website: www.wiley.com/go/chopra/retreatment

24.3 ­Treatment pla

Figure 24.1  Palatal view.

Figure 24.2  Buccal view.

Figure 24.3  Preoperative assessment.

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24  Clinical Case 24

–– Rubber dam isolation: the tooth was isolated using rubber dam with a clampless isolation technique, securing the sheet with wedgets. –– Magnification: ttreatment was performed under magnification. A dental operating microscope was used throughout the procedure. ●●

●●

●●

Treatment plan for management of the endodontic mishap and endodontic mishap repair procedure –– Removal of old obturation material from the canal. The obturation material was removed using a combination of hand K files and shaping files (2Shape® from Micro-Mega) (Figure 24.4). –– Copious irrigation with sodium hypochlorite was carried out after withdrawal of each file from the canal. –– Once all the old obturation material was removed, the working length was negotiated and the previously short working length was corrected. –– Proper shaping of the canal was done with rotary and K files. –– Thorough irrigation was carried out. Shaping –– Proper coronal flaring was done using One Flare files from Mciro-Mega. –– Canals were shaped using 2Shape (TS2, F 35 and F 40) files. –– In this case, as the apical diameter was large to begin with, hand K files sizes 50, 55 and 60 were also used. –– Interappointment medicament was placed in the canal. –– Water-based calcium hydroxide dressing was applied to this tooth for a period of 7 days. Irrigation (solution and technique) (Figure 24.5) –– 5.25% NaoCl throughout shaping and bypassing. –– Distilled water. –– 17% EDTA 1 mL per canal per minute with ultrasonic activation. –– Distilled water. –– 5.25% NaoCl with internal heating and ultrasonic activation (four cycles repeated).

Figure 24.4  Endodontic access cavity and location of previous gutta-percha.

24.3 ­Treatment pla

Figure 24.5  Endodontic irrigant in action.

●●

Obturation (materials and techniques) –– MTA apical plug was placed using MTA from Cerkamed and the carrier used was the MAP One system from Produits Dentaire. (Figure 24.6). –– A moist cotton pellet was placed in the canal for 24 hours (Figure 24.7). After 24 hours, the cotton pellet was removed, MTA was checked for setting hardness and the middle third and coronal third were dried.

Figure 24.6  MTA plug.

Figure 24.7  Cotton pellet placement.

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–– The middle third was obturated with the help of thermoplasticized gutta-percha using the EQ-V obturation device from Meta Biomed (Figure 24.8). –– The coronal third was filled with composite. ●●

Prosthetic rehabilitation: after the post endodontic restorative procedure, the tooth was prepared to receive a Zirconia crown. The immediate postoperative radiograph is shown in Figure 24.9. Figure 24.8  Placement of thermoplasticized gutta-percha.

Figure 24.9  Immediate postoperative radiograph.

­24. Follow-up

24.4 ­Technical aspects Some important aspects of an endodontic retreatment procedure include the following. ●●

●● ●●

●●

A thorough clinical examination and its correlation with radiographic readings is the first and foremost step. Magnification is a very helpful tool in retreatment cases. Irrigation plays a very important role in root canal treatments and especially in a retreatment case. Following a proper irrigation protocol for removal of both organic and inorganic debris is essential. While placing a MTA plug, before mixing the MTA, one must choose the tools carefully for that particular case and confirm their fit in the canal.

­24.5  Follow-up One-year follow up showed healing of the periapical lesion and the tooth was completely asymptomatic and functional (Figure 24.10). Figure 24.10  One-year follow-up radiograph.

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24.6 ­Learning objectives ●●

●●

●●

●●

Working length estimation and reconfirming working length time and again during the procedure helps. Irrigation and activation of irrigating solution are of high importance in teeth with a large single canal, as they generally have ovoid/irregular cross-sections and thus our instruments are unable to reach all the surfaces of the canals and ramifications if present. Using an MTA plug in such cases needs practice and preparation of your armamentarium prior to starting the procedure. While placing an MTA plug, it is a good idea to keep checking the situation on an x-ray to confirm if the plug is getting packed properly or not.

24.7 ­How can this endodontic mishap be avoided? ●● ●●

Working length determination, preferably using an electronic apex locator, is important. During the shaping procedure, sticking to the working length is important. Using a rubber stopper and measuring the working length from a stable reference point help.

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25 Nonsurgical versus surgical retreatment Decision making Meetu Ralli Kohli and Bekir Karabucak

The primary goal of endodontics is to maintain periradicular health either by treating periapical periodontitis or preventing development of disease. The reported success rate of primary root canal treatment is high at 80–90% [1, 2]. This means that a certain number of cases will not show resolution of the lesion and/or symptoms at follow-up and will need further intervention. The treatment option to address the persistent or recurrent infection can be surgical or non-surgical. Both procedures have high reported outcomes. However, success is dependent on making the correct decision for the clinical case in question. As per the definition of practising evidence-based dentistry, a clinical decision to resolve a persistent lesion should involve the evidence, the operator and the patient and their tooth. Making an evidence-based decision involves evaluating the best available evidence but should also incorporate the parameters of the current case with the skill level and comfort of the operator and the patient’s wishes and preferences [3]. The appropriate treatment choice for a persistent lesion is dependent on the assessment and combination of all these factors. In the following sections, each parameter will be reviewed in detail.

25.1 ­The evidence The first question the patient asks and the operator explores while making a choice between two treatment protocols is the reported success rate in the literature. However, an astute clinician will review this evidence critically and with due diligence. Parameters evaluated in a study reported in the literature may differ when compared to the case being evaluated by the clinician. Hence results should be critically assessed and quoted. Reported success rates for microsurgical procedures have significantly improved in the last two decades with the advent of magnification, illumination, microinstruments and biocompatible materials. When compared with traditional surgery, microsurgery has a significantly high success rate of 87–95% [4]. Using magnification, illumination, ultrasonics and biocompatible materials has increased the success rate, compared with traditional surgery done with bur, no magnification and amalgam. Meticulous execution of the microsurgical procedure will result in the best possible outcome. The key component of the procedure is to eliminate the infected apical 3 mm of the root and Clinical Atlas of Retreatment in Endodontics, First Edition. Edited by Viresh Chopra. © 2021 John Wiley & Sons Ltd. Published 2021 by John Wiley & Sons Ltd. Companion website: www.wiley.com/go/chopra/retreatment

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25  Nonsurgical versus surgical retreatment

provide an adequate seal thereafter. A 3 mm root resection has been shown to reduce the apical ramifications which can harbour bacteria by 95%. The seal is achieved best when a minimum of 3 mm preparation with ultrasonic tips along the long axis of the tooth can be carried out and filled with a well-sealing biocompatible material like MTA or newer silicate cements [5]. When all such parameters are met, the success rate of microsurgery as reported in a meta-analysis is 95.5%. However, if either of the above parameters are not met during the surgical procedure, the outcome can dramatically drop. For example, when 3 mm root is resected but instead of ultrasonic preparation and root-end filling, gutta-percha is heated with a hot instrument and burnished, the reported success rate drops dramatically from 93% to 50% [6]. Many different materials have been tested for root-end filling and the ones that have shown predictable and consistent successful outcomes are Super EBA, IRM, MTA and the newer silicate cements. MTA and IRM will not provide a hermetic seal when the depth of the preparation and root-end fill is less than 2 mm. Conditions such as this can arise when after a limited resection, there is not enough space to use an ultrasonic tip and create a 3 mm depth of preparation. In such cases, creating a concave preparation and etching prime and bond with resin-based biocompatible materials like Geristore® and Retroplast is a valid option [7]. The operator skill of keeping the area dry with no contamination becomes paramount. The reported success rate of surgery done with concave preparation and fill with resin-based materials is 85% and it is statistically less than microsurgery with ultrasonic preparations and MTA, IRM and other tricalcium silicate cements. Another factor that can affect the microsurgery outcome is the presence of a concomitant periodontal defect. A microsurgical classification for teeth has been proposed, Class A–F, wherein Class A, B and C are teeth that have lesions of endodontic origin increasing in size from barely perceptible to involving up to half the root length. Class D represents a case with a periodontal pocket that does not communicate with the endodontic lesion. Class E is when the periodontal and endodontic defects communicate and finally Class F is when upon reflection of the flap there is no buccal bone present. Surgical outcome of teeth with periodontal defects drops to 77.5%, i.e. Classes D–F  [8]. Concomitant periodontal disease needs periodontal treatment so guided tissue regeneration (GTR) and grafts are indicated in such cases. Prognostic literature on modern non-surgical retreatment is sparse compared to the surgical literature. However, evaluation of two studies suggests a common thread that if a case is selected correctly, the outcome is favourable. The first study by Gorni and Gagliani evaluates the outcome of retreatment for two groups of cases [9]. In one group, retreatment is completed on cases where the original morphology of the canal system has not been altered and the reason for the failure is an underfilled or inadequately cleaned canal space. In the second group, the reason for the failure is due to root canal morphology not being respected, which entails that during the first treatment the root canal system was violated, for example via perforation or a transportation. This condition presents a limitation wherein access to the apical third becomes unpredictable from an orthograde approach. Overall success rate for retreatment in this study was 69% but when we look at the success for teeth with morphology respected, it was 87%. When morphology was not respected and a lesion was present, the success rate dropped to 40%, suggesting that correct case selection for non-surgical treatment is a critical step. The key element to consider when making a treatment choice is the ability of the operator to gain access and disinfect the apical third of the root canal system. If the access to this portion of the root canal is questionable, the success of the orthograde retreatment becomes guarded as well. A few meta-analyses have been done to evaluate the outcome of non-surgical retreatment but they combine studies prior to the use of microscopes and other advancements

25.3 ­The patien

such as apex locators. There is a lack of investigations in regard to retreatment outcome when modern techniques are used. A recent publication investigating non-surgical retreatment of first molars with the use of microscopes, a thorough irrigation protocol with hypochlorite, EDTA and chlorhexidine reported a success rate of 88%  [10]. However, a limitation of the study was that no preoperative cone beam computed tomography (CBCT) scan was acquired to assess the anatomy of the tooth and/or the possible reason for the failure of the previous treatment. It remains questionable whether evaluation of the CBCT scan would have altered the treatment option or outcome.

25.2 ­The operator A consideration that is often not discussed is the skill of the operator. As discussed above, the clinical steps of the surgery are important and can affect the prognosis if not executed as prescribed. Hence the ability of the operator to execute the procedure to address each step effectively is important. By no means should the operator be discouraged from rendering treatment if the relevant skills are not yet acquired. The most effective way to acquire surgical skills is to perform multiple cases in the easier areas of the mouth, such as the upper anterior where the root tips are usually buccally placed and can be located easily. The soft tissue can be elevated and retracted sufficiently to gain adequate access. Maxillary premolars and molars would be the next teeth to attempt. The mandibular teeth present some measure of complexity. The mandibular premolar has easier access than the molars but can be complicated by the proximity of the mental nerve. Adequate presurgical measurements on CBCT scans and radiographs would help the operator in precision and execution of the procedure. The lower anterior can be the most unpredictable area of the mouth to work with  – first, due to lingual placement of the root tips and second, the muscle attachment that makes retraction of the lip from the surgical site difficult. Besides the surgeon’s own expertise, training of the auxiliary staff can help immensely in making the procedure smooth and efficient. Access to appropriate microsurgical instruments and materials for smooth execution of the procedure is key. Non-surgical retreatment requires a different set of operator skills. Minimal removal of dentine along with thorough disinfection of the apical third is the key to success. A major concern in a nonsurgical retreatment is the removal of dentine to disassemble the prosthesis and gain access to the root canal system. Indiscriminate removal of sound dentine can weaken the tooth considerably and make it susceptible to fracture when the tooth is placed back in function. Hence, the operator’s skill and comfort in removing the current prosthesis, finding missing canals, repairing and correcting iatrogenic errors if present and being able to thoroughly disinfect the root canal without sacrificing sound tooth structure are key to a successful outcome.

25.3 ­The patient The patient’s desires and expectations are an important aspect of treatment decision. The patient should be motivated to retain the tooth and understand the potential risks and benefits of each treatment option. Alternative options such as extraction and replacement with implants or fixed or removable prostheses should also be presented to the patient with detailed information about each procedure. The financial implications of each treatment option should be discussed to avoid

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surprises. If a new restoration is required due to damage of the current restoration or the potential to create leakage, the patient should be informed prior to commencing treatment. The patient should be happy to commit their time and finances. It has been suggested that when value base criteria are applied to treatment options, patients are more concerned with the failure itself and not necessarily the reasons for failure so their expectations should be reasonably managed prior to institution of treatment. Besides participation and consent of the patient to institute treatment, their medical history evaluation is paramount for treatment planning. The final treatment plan will be dependent on whether the patient can tolerate the treatment or not. There are not many contraindications for non-surgical intervention but for microsurgery, certain medical conditions and medicaments that the patient is taking may be prohibitive.

25.4 ­Medical history The health history of the patient can affect treatment choice. Medical history evaluation is a critical preoperative step. Some conditions that present as absolute contraindications to surgical intervention are hyperthyroidism, phaeochromocytoma, high blood pressure greater than 200/115 mmHg, cardiac dysrhythmias, unstable angina and myocardial infarction or cerebrovascular event within the last 6 months. Uncontrolled diabetes can present a challenge for patient management during a surgical approach as well. HbA1c greater than 7% should be considered cautiously as the healing capacity of the patient is compromised at higher glucose levels. Care of the surgical wound becomes very important and PeridexTM and a prophylactic antibiotic are recommended.

2 ­ 5.5 

Medications

Non-surgical endodontic treatment does not present many contraindications in terms of medicaments that have been prescribed to the patient by their physician. The main concern with most cases is limiting epinephrine for patients with cardiovascular disease. Two carpules of 2% lidocaine with 1:100 000 epinephrine, i.e. 0.04 mg/mL of epinephrine, is considered safe for all cardiac patients. However, if surgical treatment is chosen, use of epinephrine should be considered carefully. To achieve adequate haemostasis, 2% lidocaine with 1:50 000 is advocated. Two to three carpules of anaesthetic are generally required to gain profound anaesthesia, hence a consult with the physician is recommended. Anaesthetic should be administered slowly and with caution so as not to raise the blood pressure. If administration of epinephrine is contraindicated by the patient’s physician, the surgical approach is generally not possible. Coagulation and bleeding time of the patient should be assessed for surgical treatment. Normal INR is 1 but therapeutic INR with anticoagulants can be as high as 3.5. INR considered safe for surgical intervention is 1.5. INR values should be acquired and a decision made whether the anticoagulant, such as heparin and warfarin, should be stopped and at what point preoperatively, in consultation with the physician. Adequate time should be allowed for wound closure and stabilization before resuming anticoagulants postsurgically. Patients taking over-the-counter baby aspirin might present with some bleeding concerns during surgery. Although there is no evidence that uncontrolled intraoperative or postoperative bleeding is

­25.  The tooth: factors to consider

observed with low-dose aspirin, excessive bleeding intraoperatively can be of concern in terms of execution of the procedure. If the operator decides to ask the patient to stop taking baby aspirin, in order for the antiplatelet effect to be purged, it should be stopped at least 10 days before the surgery. Bisphosphonates, antiresorptive and antiangiogenic drugs may pose a true contraindication for surgical intervention. Case reports of medication-related osteonecrosis are abundant in the literature so the patient’s drug history should be carefully evaluated before surgery. The American Association of Oral and Maxillofacial Surgeons and the American Association of Endodontics released an update in 2014 that categorized patient risk factors [11]. Patients taking oral bisphosphonates for less than 4 years pose a minimal risk for developing osteonecrosis at 0.05%. No modification in the drug dosage is recommended for low-risk patients. Patients taking oral bisphosphonates for more than 4 years or who have been taking corticosteroids along with their bisphosphonates for any period are categorized as medium risk. A drug holiday for 2 months before and 3 months following the surgery is recommended. High-risk patients are those who have been on IV bisphosphonates. Surgical intervention is generally not indicated for these patients but extractions can present a challenge as well. Non-surgical treatment and retention of the tooth is the best option for high-risk patients. Care should be taken with these patients to avoid injury to the soft tissue and bone. Use of patency files and rubber dam clamps that impinge on soft tissue or bone, and overextension of filling materials should be avoided.

­25.6  The tooth: factors to consider Persistent periapical pathology The nature of the persistent disease can sometimes dictate the outcome of the treatment rendered. Nair’s evaluation of biopsy of persistent pathology classifies lesions into granulomas, cysts and foreign body reactions [12, 13]. Radicular cysts are further classified as true cysts and bay cysts. Bay cysts communicate with the root canal system where the cyst lumen is continuous with the necrotic root canal.True cysts are structurally independent lesions inside the body of the periapical lesion with no continuity with the root canal. It is suggested in the literature that true cysts will not resolve with non-surgical intervention. Unfortunately, there are no pathognomonic presentations on x-ray or CBCT that will provide the histological diagnosis [14] so the operator should follow up closely for healing when non-surgical treatment is instituted. If the lesion does not heal, surgery will be indicated. Biopsy of surgical samples is recommended. Similarly, persistent lesions due to extruded material or foreign body reactions will need surgical excision to provide a favourable response. Hence, a case with obvious extruded material and a lesion associated with it may be predisposed to make surgical treatment the primary option.

Presurgical CBCT evaluation Treatment of any disease process involves evaluation of the aetiology. Once an exhaustive list of possible aetiological factors is enumerated, the procedure that has the best ability to address the potential aetiology should be considered the procedure of choice. Cone beam tomography has added a new dimension to visualization of the tooth. Several angulated x-rays were recommended to assess the root canal fill and the anatomy of the tooth in a failed

191

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25  Nonsurgical versus surgical retreatment

endodontic procedure. Limitations of x-rays include the anatomical noise and inherent observer bias. However, CBCT gives a detailed view of the tooth and its surrounding structures. A small field of view CBCT is recommended prior to treatment planning. CBCT can be invaluable in the decision-making process in determining whether a surgical or non-surgical intervention is suitable for the case. A preoperative CBCT can also avoid putting the patient through an unnecessary procedure when an extraction is indicated. Although the presence of vertical root fracture cannot be very accurately detected in a scan due to scatter from the root-filling materials, the bone destruction can suggest its presence. Once a surgical intervention is planned, the software allows the clinician to make all necessary measurements preoperatively, such as whether fenestration of bone is present, root length, depth of osteotomy, proximity of anatomical structures, etc., hence shortening the duration of the surgery and making it a precise, well-targeted and predictable procedure. Important landmarks can be identified and complications avoided, such as proximity of the mental foramen, mandibular canal, sinus cavity, proximity to neighbouring vital teeth, etc.

­25.7  Quality of restoration and post The integrity of the coronal restoration in the presence of post-treatment disease is an important consideration. Surgical treatment is not an option if the restoration is leaking or has recurrent decay. Similarly, a large well-placed restoration should not be disturbed if the aetiology of the lesion can be addressed surgically. Removal of a large and long post can often be deleterious to the remaining tooth structure; it can weaken the roots and predispose them to fracture and hence a catastrophic result. The risks involved in disassembling a large well-seated restoration are an important consideration in deciding between surgical and non-surgical approaches. The operator and their skills are central in this decision making.

25.8  ­Root canal obturation quality and iatrogenic errors The most common reason for failure of root canal treatment is inadequate disinfection and obturation of the space. A poorly disinfected and obturated root canal is ideally not a candidate for surgical intervention. Surgical intervention addresses the apical 6 mm of the root canal by resecting 3 mm and prepping another 3 mm with ultrasonic tips. However, if there are missed anatomies and the entire system is underfilled, addressing the deficiency non-surgically first is indicated. Iatrogenic errors made during primary root canal treatment can further complicate the disinfection during revision of the treatment. For example, a separated file will not allow the irrigants and medicaments to reach the portion of the root canal at and beyond the instrument. If non-surgical retreatment is chosen, removal of the separated file without weakening the root canal system is the key. Similarly, a perforation can also make the disinfection process challenging. A perforation needs to be repaired with biocompatible material like MTA or trisilicate cements. The location of the perforation will dictate whether it can be adequately sealed or not. Both delayed and immediate repair of perforations, if adequately done, have been shown to have a favourable outcome [15]. The primary aim is disinfection and providing a seal at the site of perforation so the treatment option that achieves that aim will be the treatment of choice.

25.9 ­Three clinical case

25.9 ­Three clinical cases Cases that exemplify some of the above-mentioned indications are presented below.

Case 1 – preoperative microsurgical planning using CBCT imaging The following clinical case will present the advantages of the CBCT imaging technique in the preparation and execution of surgery. 1) Preoperative and postoperative x-rays (Figure 25.1). 2) Coronal, sagittal and axial views of the CBCT images of the mesial and distal roots (Figure 25.2). 3) Preoperative measurements: length of the root from a reproducible point; margin of the crown; distance from crown margin to mandibular canal; distance between two roots at the 3 mm mark if both roots need treatment; depth of resection from the cortical plate to the lingual end of the Figure 25.1  Preoperative and postoperative x-rays.

Preoperative

CORONAL

Postoperative

SAGITTAL

AXIAL

MESIAL ROOT

DISTAL ROOT

Figure 25.2  Coronal, sagittal and axial views of the CBCT images of the mesial and distal roots.

193

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25  Nonsurgical versus surgical retreatment Measurements

sagittal

coronal

axial

Figure 25.3  Preoperative measurements: length of the root from a reproducible point; margin of the crown; distance from crown margin to mandibular canal; distance between two roots at the 3 mm mark if both roots need treatment; depth of resection from the cortical plate to the lingual end of the root at the 3 mm mark. This measurement avoids excessive removal of bone and helps to preserve the lingual cortical plate.

root at the 3 mm mark. This measurement avoids excessive removal of bone and helps to preserve the lingual cortical plate (Figure 25.3). 4) Location of the mental foramen from the alveolar crest. Note the coronal exit of the mental foramen from the mandibular canal. Measurement of the mental foramen from the surgical site (Figure 25.4).

Case 2 – decision for non-surgical retreatment due to missed anatomy Cone beam CT imaging was used to locate and treat canals. 1) Preoperative radiographs and bitewing x-rays: sinus tract tracing (Figure 25.5). 2) CBCT imaging of mesial and distal roots: missed lingual canals on both roots (Figure 25.6). 3) Location of orifices of ML, MM, MB, DB and DL canals (Figure 25.7). 4) Postoperative x-rays (Figure 25.8). Mental Foramen

Figure 25.4  Location of the mental foramen from the alveolar crest. Note the coronal exit of the mental foramen from the mandibular canal. Measurement of the mental foramen from the surgical site.

25.9 ­Three clinical case Pre-Op: PA+BWs

Figure 25.5  Preoperative radiographs and bitewing x-rays: sinus tract tracing.

Pre-Op: CBCT M root

Pre-Op: CBCT D root

Figure 25.6  CBCT imaging of mesial and distal roots: missed lingual canals on both roots.

195

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25  Nonsurgical versus surgical retreatment

Figure 25.7  Location of orifices of ML, MM, MB, DB and DL canals. M

M

M

DB

Shift Shot

M

D

Figure 25.8  Postoperative x-rays.

Post-Op

Straight

25.9 ­Three clinical case

Case 3 – decision for surgical treatment: PAP on mesial root only and no missed anatomy 1) Preoperative x-ray and bitewing showing a sound clinical crown and post in the palatal root (Figure 25.9). 2) CBCT images show no missed anatomy with lesion only on the mesial root (Figure 25.10). 3) Clinical pictures: preoperative soft tissue with sinus tract over MB root (Figure 25.11). After flap reflection, dehiscence of the cortical plate over MB root (Figure 25.12). Resected root surface with methylene blue staining showing leakage around the fill and no missed anatomy (Figure 25.13). Root-end preparation (Figure 25.14). 4) Preoperative, postoperative and 6-month follow-up x-rays show bone fill with lamina dura reconstitution (Figure 25.15).

Figure 25.9  Preoperative x-ray and bitewing showing a sound clinical crown and post in the palatal root.

Figure 25.10  CBCT images show no missed anatomy with lesion only on the mesial root.

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25  Nonsurgical versus surgical retreatment

Figure 25.11  Preoperative soft tissue with sinus tract over the MB root.

Figure 25.12  After flap reflection, dehiscence of the cortical plate over the MB root.

Figure 25.13  Resected root surface with methylene blue staining showing leakage around the fill and no missed anatomy.

Figure 25.14  Root-end preparation.

 ­Reference

Pre-op

Post-op

6 month follow up

Figure 25.15  Preoperative, postoperative and 6-month follow-up x-rays.

R ­ eferences 1 Ng Y-L, Mann V, Rahbaran S, Lewsey J, Gulabivala K. Outcome of primary root canal treatment: systematic review of the literature – part 2. Influence of clinical factors. Int Endod J 2008;41(1): 6–31. 2 Ng Y-L, Mann V, Rahbaran S, Lewsey J, Gulabivala K. Outcome of primary root canal treatment: systematic review of the literature – part 1. Effects of study characteristics on probability of success. Int Endod J 2007;40(12):921–39. 3 Brignardello-Petersen R, Carrasco-Labra A, Booth HA, et al. A practical approach to evidence-based dentistry. J Am Dent Assoc 2014;145(12):1262–7. 4 Setzer FC, Shah SB, Kohli MR, Karabucak B, Kim S. Outcome of endodontic surgery: a metaanalysis of the literature – part 1: comparison of traditional root-end surgery and endodontic microsurgery. J Endod 2010;36(11):1757–65. 5 Kim S, Kratchman S. Microsurgery in Endodontics. Hoboken, NJ: John Wiley & Sons, Inc.; 2017. 6 Christiansen R, Kirkevang L-L, Hørsted-Bindslev P, Wenzel A. Randomized clinical trial of root-end resection followed by root-end filling with mineral trioxide aggregate or smoothing of the orthograde gutta-percha root filling – 1-year follow-up. Int Endod J 2009;42(2):105–14. 7 Kohli MR, Berenji H, Setzer FC, Lee S-M, Karabucak B. Outcome of endodontic surgery: a metaanalysis of the literature – part 3: comparison of endodontic microsurgical techniques with 2 different root-end filling materials. J Endod 2018;44(6):923–31. 8 Kim E, Song J-S, Jung I-Y, Lee S-J, Kim S. Prospective clinical study evaluating endodontic microsurgery outcomes for cases with lesions of endodontic origin compared with cases with lesions of combined periodontal–endodontic origin. J Endod 2008;34(5):546–51. 9 Gorni FGM, Gagliani MM. The outcome of endodontic retreatment: a 2-yr follow-up. J Endod 2004; 30:4.

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10 He J, White RK, White CA, Schweitzer JL, Woodmansey KF. Clinical and patient-centered outcomes of nonsurgical root canal retreatment in first molars using contemporary techniques. J Endod 2017; 43(2):231–7. 11 Ruggiero SL, Dodson TB, Fantasia J, et al. American Association of Oral and Maxillofacial Surgeons Position Paper on medication-related osteonecrosis of the jaw – 2014 update. J Oral Maxillofac Surg 2014;72(10):1938–56. 12 Nair PNR. On the causes of persistent apical periodontitis: a review. Int Endod J 2006;39(4):249–81. 13 Nair PNR, Sjögren U, Figdor D, Sundqvist G. Persistent periapical radiolucencies of root-filled human teeth, failed endodontic treatments, and periapical scars. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1999;87(5):617–27. 14 Rosenberg PA, Frisbie J, Lee J, et al. Evaluation of pathologists (histopathology) and radiologists (cone beam computed tomography) differentiating radicular cysts from granulomas. J Endod 2010;36(3):423–8. 15 Siew K, Lee AHC, Cheung GSP. Treatment outcome of repaired root perforation: a systematic review and meta-analysis. J Endod 2015;41(11):1795–804.

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Index Page numbers in italics for figures.

a

American Association of Endodontists case assessment criteria  81 asymptomatic lateral periodontitis associated with cast post  51–57 avoiding endodontic mishap  57 clinical findings  51 dental history  51 diagnosis  51 follow‐up  56, 56 learning objectives  56 patient information  51 preoperative radiological assessment  51, 52 technical aspects  54, 55–56 treatment plan  51–54, 52–54

c

cone beam computed tomography (CBCT)  80, 189

e

endodontic failure cases asymptomatic lateral periodontitis associated with cast post  51–57 endodontic‐periodontal lesion following a previous root canal treatment  58–63 instrument retrieval from mandibular left first premolar  23–31 mandibular molar with fractured instrument extending in periapical area  128–133 non‐surgical retreatment of maxillary anterior tooth using static guidance  79–97 on tooth 11  87–95 versus surgical retreatment  193–199 perforation repair with instrument retrieval  32–37 pulpal floor perforation  5–9 with periapical lesion in the mesial root  99–107 retreatment of tooth 16  17–22 retreatment of tooth 21  180–186

root canal treatment failure  108–113 with faulty cast post and asymptomatic lateral periodontitis  51–57 with inadequate obturation and apically calcified canals  134–139 with inadequate obturation and faulty post placement  154–160 with inadequate obturation and missed canals  140–146 with inadequate obturation, fractured instrument and periapical lesion in mandibular left first molar  172–179 with inadequate obturation, hidden fractured instrument and ledge formation in a severely curved mandibular molar  114–120 with inadequate obturation, multiple perforations, fractured instrument and ledge formation in maxillary right first molar  161–171 with inadequate obturation, unusual distal root anatomy  147–153 with an instrument fracture in a mandibular molar  121–127 maxillary molar with selective root treatment  69–78 with missed canal anatomy and inadequate obturation  108–113 with missed lateral canal anatomy and inadequate obturation  45–50 with silver cone obturation and fractured instrument  64–68 strip perforation repair and fractured instrument  38–44 surgical removal of fractured instrument  10–16 endodontic‐periodontal lesion following previous root canal treatment  58–63 avoiding endodontic mishap  63 clinical findings  58, 59 dental history  58 diagnosis  58 follow‐up  61, 62

Clinical Atlas of Retreatment in Endodontics, First Edition. Edited by Viresh Chopra. © 2021 John Wiley & Sons Ltd. Published 2021 by John Wiley & Sons Ltd. Companion website: www.wiley.com/go/chopra/retreatment

202

Index endodontic‐periodontal lesion following previous root canal treatment (cont’d) learning objectives  61–62 patient information  58 preoperative radiological assessment  58, 59 treatment plan  58–60, 61 endodontic treatment aim of  2–3 classification of  2 definition of  1–2 endodontic failures, causes for  2

g

guided endodontics  79, 80 approach to planning  83–85, 83–87 FAQs for  96 improving accuracy of access preparation  80–81, 81 static guidance, 81–82. See also static guidance steps for planning and printing  85–86, 85–87 guided tissue regeneration (GTR)  188

i

instrument retrieval from mandibular left first premolar  23–31 avoiding endodontic mishap  31 clinical findings  23 dental history  23 diagnosis  23 follow‐up  30, 30 learning objectives  31 patient information  23 preoperative radiological assessment  23, 24 removal of fractured instrument  29–30 treatment plan  23–29, 24–29

l

local anaesthesia (IANB)  11

m

mandibular molar with fractured instrument avoiding endodontic mishap  133 clinical findings  128, 129 dental history  128 diagnosis  128 learning objectives  132 patient information  128 preoperative radiological assessment  128, 129 technical aspects  132 treatment plan  128–130, 129–132

n

non‐surgical endodontic retreatment  2 non‐surgical re‐root canal treatment (NSRRCT)  11 non‐surgical retreatment due to missed anatomy  194–195, 194–196 non‐surgical retreatment on tooth 11

avoiding endodontic mishap  95 clinical findings  87 dental history  87 diagnosis  87 follow‐up  91, 95 learning objectives  95 patient information  87 preoperative radiological assessment  87, 88 technical aspects  90–91 treatment plan  87–90, 88–95 nonsurgical versus surgical retreatment clinical cases  193–199 coagulation and bleeding time of the patient for  190–191 evidence‐based dentistry  187–189 factors to consider  191–192 persistent periapical pathology  191 presurgical CBCT evaluation  191–192 medical history  190 medications  190–191 operator skills  189 patient’s desires and expectations  189–190 quality of restoration and post  192 root canal obturation quality and iatrogenic errors  192

p

perforation repair with instrument retrieval  32–37 avoiding endodontic mishap  37 clinical findings  32 dental history  32 diagnosis  32 follow‐up  35, 36 learning objectives  35–36 patient information  32 preoperative radiological assessment  32, 33 technical aspects  35 treatment plan  33–34, 34–35 preoperative microsurgical planning using CBCT imaging  193–194, 193–194 pulpal floor perforation avoiding endodontic mishap  9 follow‐up  7, 9 learning objectives  9 patient information  5 technical aspects  7 clinical findings  5 dental history  5 diagnosis  5 treatment plan  5–7, 6–8 pulpal floor perforation with periapical lesion in the mesial root  99–107 avoiding endodontic mishap  107 clinical findings  99 dental history  99 diagnosis  99 follow‐up  106, 106 learning objectives  106–107

Index patient information  99 preoperative radiological assessment  99, 100 technical aspects  105 treatment plan  100–103, 101–106 pulp canal calcification (PCC)  79

r

retreatment of maxillary anterior tooth using static guidance  79–87 retreatment of tooth 16  17–22 avoiding endodontic mishap  22 clinical findings  17, 18 dental history  17 diagnosis  17 follow‐up  21, 22 learning objectives  21 obturation  20, 21 patient information  17 shaping  20 solution and technique  20 technical aspects  20–21 preoperative radiological assessment  17, 18 treatment plan  18–20, 19–20 retreatment of tooth 21  180–186 avoiding endodontic mishap  186 clinical findings  180, 181 dental history  180 diagnosis  180 follow‐up  185, 185 learning objectives  186 patient information  180 preoperative radiological assessment  180, 181 technical aspects  185 treatment plan  180–184, 182–184 root canal retreatment, indications for  1 root canal system (RCS)  2 root canal treatment failure with an instrument fracture in mandibular molar  121–127 avoiding endodontic mishap  127 clinical findings  121 dental history  121 diagnosis  121 follow‐up  126, 126 learning objectives  126–127 patient information  121 preoperative radiological assessment  121, 122 technical aspects  126 treatment plan  121–124, 122–125 maxillary molar with selective root treatment  69–78 avoiding endodontic mishap  50 clinical findings  45 dental history  45 diagnosis  45 follow‐up  48, 49 learning objectives  50 patient information  45 preoperative radiological assessment  45, 46

technical aspects  48 treatment plan  45–48, 47–48 with missed canal anatomy and inadequate obturation  108–113 avoiding endodontic mishap  113 clinical findings  108 dental history  108 diagnosis  108 follow‐up  112, 113 learning objectives  112 patient information  108 preoperative radiological assessment  108, 109 technical aspects  112 treatment plan  109–111, 109–112 with silver cone obturation and fractured instrument  64–68 avoiding endodontic mishap  68 clinical findings  64, 65 dental history  64 diagnosis  64 follow‐up  67, 68 learning objectives  67–68 patient information  64 preoperative radiological assessment  64 technical aspects  67 treatment plan  64–67, 65–67 maxillary molar with selective root treatment avoiding endodontic mishap  50 clinical findings  45 dental history  45 diagnosis  45 follow‐up  48, 49 learning objectives  50 patient information  45 preoperative radiological assessment  45, 46 technical aspects  48 treatment plan  45–48, 47–48 root canal treatment failure with inadequate obturation and apically calcified canals  134–139 avoiding endodontic mishap  139 clinical findings  134 dental history  134 diagnosis  134 follow‐up  138, 138–139 learning objectives  138 patient information  134 preoperative radiological assessment  134, 135 technical aspects  137–138 treatment plan  134–136, 135–137 and faulty post placement  154–160 avoiding endodontic mishap  160 clinical findings  154 dental history  154 diagnosis  154 follow‐up  160 learning objectives  160 patient information  154 preoperative radiological assessment  154, 155

203

204

Index root canal treatment failure with inadequate obturation (cont’d) technical aspects  159–160 treatment plan, in different stages  162–168, 163–169 fractured instrument and periapical lesion in left mandibular first molar  172–179 avoiding endodontic mishap  179 clinical findings  172 dental history  172 diagnosis  172 follow‐up  178, 179 learning objectives  178–179 patient information  172 preoperative radiological assessment  172, 173 technical aspects  178 treatment plan  172–178, 172–177 hidden fractured instrument and ledge formation in a severely curved mandibular molar  114–120 avoiding endodontic mishap  120 clinical findings  114 dental history  114 diagnosis  114 follow‐up  119 learning objectives  119 patient information  114 preoperative radiological assessment  114, 115 technical aspects  118–119 treatment plan,115–118  115–119 and missed canals  140–146 avoiding endodontic mishap  146 clinical findings  140 dental history  140 diagnosis  140 follow‐up  145 learning objectives  145 patient information  140 preoperative radiological assessment  140, 141 technical aspects  145 treatment plan  141–144, 141–144 multiple perforations, fractured instrument and ledge formation in maxillary right first molar  161–171 avoiding endodontic mishap  171 clinical findings  161 dental history  161 diagnosis  161 follow‐up  170, 170 learning objectives  170 patient information  161 preoperative radiological assessment  161, 162 technical aspects  168–169 treatment plan  162–168, 163–169 unusual distal root anatomy and suspected ledge formation in a mandibular molar  147–153 avoiding endodontic mishap  153 clinical findings  147

dental history  147 diagnosis  147 follow‐up  152, 153 learning objectives  152–153 patient information  147 preoperative radiological assessment  147, 148 technical aspects  151–152 treatment plan  148–151, 148–152

s

selective root retreatment on MB root avoiding endodontic mishap  78 clinical findings  71, 71–72 conclusion  77 decision making  69–70 dental history  71 diagnosis  69 follow‐up  77, 77 learning objectives  77 patient information  71 selective retreatment, steps for  70 technical aspects  74 treatment option  69 treatment plan  70, 71–74, 73–76 static guided endodontics  81–82, 82 advantages  82 burs used for  87 challenges with  83 disadvantages  82–83 strip perforation repair and fractured instrument  38–44 avoiding endodontic mishap  44 clinical findings  38 dental history  38 diagnosis  38 follow‐up  41, 43 learning objectives  43–44 patient information  38 preoperative radiological assessment  38, 39 technical aspects  41 treatment plan  39–41, 40–43 surgical endodontic retreatment  2 surgical removal of fractured instrument  10–16 clinical findings  10 dental history  10 diagnosis  10 follow‐up  16, 16 learning objectives  16 patient information  10 preoperative radiological assessment  10, 11 surgical procedure  12–14, 13–15 technical aspects  16 treatment plan  11–12, 11–12 surgical treatment, PAP on mesial root only and no missed anatomy  197–198, 197–199