Endodontic Practice US Spring 2019 Vol 12 No 1

clinical articles • management advice • practice profiles • technology reviews Spring 2019 – Vol 12 No 1 • endopracticeus.com

PROMOTING

EXCELLENCE

Endodontic retreatment: a conservative and predictable therapy Dr. Jorge Alberdi

Mandibular first molar with four canals in the mesial root Drs. Hamed Karkehabadi, Ricardo Machado, and Lucas da Fonseca Roberti Garcia

IN

ENDODONTICS The cortical window – part 1 Drs. Naheed Mohamed, Yosi Nahmias, and Ken Serota

A comparative study between the single gutta-percha cone technique and GuttaCore Drs. Juan Antonio Araujo, Carlos Cantarini, Viviana Han, and Fernando Goldberg

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ASSOCIATE EDITORS Julian Webber, BDS, MS, DGDP, FICD Pierre Machtou, DDS, FICD Richard Mounce, DDS Clifford J Ruddle, DDS John West, DDS, MSD EDITORIAL ADVISORS Paul Abbott, BDSc, MDS, FRACDS, FPFA, FADI, FIVCD Professor Michael A. Baumann Dennis G. Brave, DDS David C. Brown, BDS, MDS, MSD L. Stephen Buchanan, DDS, FICD, FACD Gary B. Carr, DDS Arnaldo Castellucci, MD, DDS Gordon J. Christensen, DDS, MSD, PhD B. David Cohen, PhD, MSc, BDS, DGDP, LDS RCS Stephen Cohen, MS, DDS, FACD, FICD Simon Cunnington, BDS, LDS RCS, MS Samuel O. Dorn, DDS Josef Dovgan, DDS, MS Tony Druttman, MSc, BSc, BChD Chris Emery, BDS, MSc. MRD, MDGDS Luiz R. Fava, DDS Robert Fleisher, DMD Stephen Frais, BDS, MSc Marcela Fridland, DDS Gerald N. Glickman, DDS, MS Kishor Gulabivala, BDS, MSc, FDS, PhD Anthony E. Hoskinson BDS, MSc Jeffrey W Hutter, DMD, MEd Syngcuk Kim, DDS, PhD Kenneth A. Koch, DMD Peter F. Kurer, LDS, MGDS, RCS Gregori M. Kurtzman, DDS, MAGD, FPFA, FACD, DICOI Howard Lloyd, BDS, MSc, FDS RCS, MRD RCS Stephen Manning, BDS, MDSc, FRACDS Joshua Moshonov, DMD Carlos Murgel, CD Yosef Nahmias, DDS, MS Garry Nervo, BDSc, LDS, MDSc, FRACDS, FICD, FPFA Wilhelm Pertot, DCSD, DEA, PhD David L. Pitts, DDS, MDSD Alison Qualtrough, BChD, MSc, PhD, FDS, MRD RCS John Regan, BDentSc, MSC, DGDP Jeremy Rees, BDS, MScD, FDS RCS, PhD Louis E. Rossman, DMD Stephen F. Schwartz, DDS, MS Ken Serota, DDS, MMSc E Steve Senia, DDS, MS, BS Michael Tagger, DMD, MS Martin Trope, BDS, DMD Peter Velvart, DMD Rick Walton, DMD, MS John Whitworth, BchD, PhD, FDS RCS CE QUALITY ASSURANCE ADVISORY BOARD Dr. Alexandra Day, BDS, VT Julian English, BA (Hons), editorial director FMC Dr. Paul Langmaid, CBE, BDS, ex chief dental officer to the Government for Wales Dr. Ellis Paul, BDS, LDS, FFGDP (UK), FICD, editor-inchief Private Dentistry Dr. Chris Potts, BDS, DGDP (UK), business advisor and ex-head of Boots Dental, BUPA Dentalcover, Virgin Dr. Harry Shiers, BDS, MSc (implant surgery), MGDS, MFDS, Harley St referral implant surgeon © FMC 2019. All rights reserved.

The publisher’s written consent must be obtained before any part of this publication may be reproduced in any form whatsoever, including photocopies and information retrieval systems. While every care has been taken in the preparation of this magazine, the publisher cannot be held responsible for the accuracy of the information printed herein, or in any consequence arising from it. The views expressed herein are those of the author(s) and not necessarily the opinion of either Endodontic Practice US or the publisher.

New technology — awesome or awful?

A

s doctors, we have expectations of ourselves. Our patients and referring doctors also have expectations of us. Endodontists are tasked with performing standard-of-care treatment and staying abreast of the latest dental technologies — many of which are expensive and challenging to learn. It is easy to feel pressured to keep up with the latest trends just as it is to lag behind them. How can we identify which of these emerging technologies are worth adopting, and which will only collect dust on our shelves?

Assessing the value of new dental technology requires focus Adam Davis, DDS on patient-centered outcomes. In endodontics, those outcomes are typically pain-free function and elimination of odontogenic infection. If a dental technology is advertised to achieve those outcomes more readily than you can currently offer, it is worth seeking supporting evidence and testimonials from trusted colleagues. If the technology is proven, and you are committed to rendering the best care for your patients, the logistics of affording and implementing it into your practice becomes secondary.

Reflecting on our specialty’s technological history, we can identify several key advances that have revolutionized our field. The standardization of hand files, the surgical operating microscope, nickel-titanium rotary files, digital radiographs, electronic patient records, and cone beam CT have all become staples of the modern endodontic practice. Vying to earn a position in that growing list, several technologies have emerged such as soft and hard tissue lasers, the GentleWave®, and X-Guide™. Leaders tend to be early adopters of these technologies. Our patients deserve that investment, and they certainly don’t expect us to hold steadfast to what we learned decades ago.

To that end, I believe that new technologies ought to be vetted by three critical questions. First, does this technology improve patient care for a significant portion of my patients?

Second, is it reliable and robust enough to endure repeated use or have a reasonable repair cost? Last, will this technology increase practice revenue or strictly serve as an additional expense of business?

In a market where manufacturers and their catalogues compete for our attention, endodontists must decide which of the latest technologies are masquerading as progress and which are capable of delivering results. Patients expect their doctors to be technologically oriented. To meet that expectation, we must gather information, assess the technology both on its own merit and as it fits into our practice, and execute a decision. It is easy to fall prey to the inertia of our current success, but greater rewards come to those seeking to improve their practice in accordance to the times. We should view dental technology as an opportunity and not a burden. Question, be critical, seek counsel, but also be ready to move forward with new technology that benefits your patients!

Adam Davis, DDS

Adam Davis, DDS, graduated from the University of Tennessee College of Dentistry in 2001. He spent 5 years serving as a general dentist in the U.S. Navy. After fulfilling his active duty commitment, Dr. Davis entered the Endodontic Residency Program at Virginia Commonwealth University in Richmond, Virginia. He received his Endodontic Specialty Certificate in June 2008. In July 2008, Dr. Davis opened Cumberland Endodontics with the goal of providing residents in the greater Nashville area with the finest endodontic care available.

ISSN number 2372-6245

Volume 12 Number 1

Endodontic practice 1

INTRODUCTION

Spring 2019 - Volume 12 Number 1

TABLE OF CONTENTS

Case study Bioceramic liner material: bridging the gap between bioceramics and restorative materials Dr. Allen Ali Nasseh discusses a new bioactive, dual-cure liner.................. 18

Practice profile Anushree Mehrotra, BDS, MDS, DDS, MS

6

Bringing patients relief and healing

Clinical Use of cone-beam computed tomography and ultrasound for the removal of gutta-percha extruded into the maxillary sinus Drs. Clovis Monteiro Bramante, Jussaro Alves Duque, Murilo Priori Alcalde, Victor de Moraes Cruz, Alexandre Silva Bramante, Talita Tartari, Braulio Pasternak Jr, Cesar Augusto Pereira Oliveira, and Marco Antonio Hungaro Duarte discuss helpful tools to aid in the planning of endodontic surgeries....................... 24

Clinical research The effectiveness of different rotary systems in the removal of gutta-percha and sealer obturation in ovoid canals

Clinical 12 Endodontic retreatment: a conservative and predictable therapy Dr. Jorge Alberdi highlights the importance of endodontic retreatment for tooth conservation

Drs. Aline Yumi Mukai, Ana Grasiela da Silva Limoeiro, Alexandre Sigrist De Martin, Augusto Shoji Kato, Carlos Eduardo da Silveira Bueno, Daniel GuimarĂŁes Pedro Rocha, Rina Andrea Pelegrine, and Carlos Eduardo Fontana discuss different systems for the removal of obturation material .......................................................30

ON THE COVER Cover image courtesy of Drs. Juan Antonio Araujo, Carlos Cantarini, Viviana Han, and Fernando Goldberg.

See article on page 38.

2 Endodontic practice

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TABLE OF CONTENTS

Research A comparative study between the single gutta-percha cone technique and GuttaCore in the filling of simulated lateral canals Drs. Juan Antonio Araujo, Carlos Cantarini, Viviana Han, and Fernando Goldberg study different techniques for obturating lateral canals in premolars .......................................................38

Continuing education The cortical window – part 1

42

Drs. Naheed Mohamed, Yosi Nahmias, and Ken Serota discuss the evolution of endodontic surgery in the first of this 2-part article

Continuing education Mandibular first molar with four canals in the mesial root Drs. Hamed Karkehabadi, Ricardo Machado, and Lucas da Fonseca Roberti Garcia describe a case report of a mandibular first molar showing the presence of four canals in the mesial and two canals in the distal root ....................................................... 46

Endodontic insight Endodontic retreatment utilizing a conservative guttapercha removal instrument Dr. Nishan Odabashian discusses how this instrument benefits his retreatment process............................................50

Practice management How to increase your clinical efficiency and profitability Dr. Albert (Ace) Goerig discusses three main areas that may need change in your practice .................................. 52

Product profile Built to Last. Built for You. Built by Boyd. ....................................................... 55

PUBLISHER | Lisa Moler Email: lmoler@medmarkmedia.com MANAGING EDITOR | Mali Schantz-Feld, MA Email: mali@medmarkmedia.com | Tel: (727) 515-5118 ASSISTANT EDITOR | Elizabeth Romanek Email: betty@medmarkmedia.com VP, SALES & BUSINESS DEVEL. | Mark Finkelstein Email: mark@medmarkmedia.com CLIENT SERVICES/SALES SUPPORT | Adrienne Good Email: agood@medmarkmedia.com NATIONAL ACCOUNT MANAGER | Celeste Scarfi-Tellez Email: celeste@medmarkmedia.com CREATIVE DIRECTOR/PROD. MGR. | Amanda Culver Email: amanda@medmarkmedia.com

Small talk Expect success Dr. Joel C. Small discusses how expectation of performance affects behavior.......................................... 56

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4 Endodontic practice

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PRACTICE PROFILE

Anushree Mehrotra, BDS, MDS, DDS, MS Bringing patients relief and healing What can you tell us about your background?

I was born in India; my father is a periodontist and mother, a professor of English Literature. I graduated from dental school in 2004 and completed a Masters in Oral Pathology in India. I was actively involved in research and attached to a dental school, teaching and guiding research. During this time, I got an opportunity to present my research at the American Association of Oral Pathologists in San Francisco and received the AAOMP Dental Award for the same. This encouraged me to study further and pursue a DDS in the United States to enhance my techniques and knowledge of dentistry. My brother, a practicing neonatologist here, encouraged and supported me. Though a big change initially, over a period of time, I adjusted and grew to love all positive aspects of America. During this transition, I had immense support from my family, which made this transition smoother.

I received multiple scholarships, the AAE student award, was on the Dean’s list, and earned my DDS as magna cum laude from Marquette Dental School.

Tooth pain is an excruciating experience; relieving patients of discomfort and saving teeth became my passion. My husband, an endodontist, encouraged and supported me to learn more about endodontics. I completed my endodontic residency at Marquette Dental School. During the residency, I received first position for my poster and research presentation in both first and second years, respectively. Learning and practicing endodontics has been an enriching experience. I currently practice at Advanced Dental Specialists, Waukesha North.

My professional affiliations include membership in the American Association of Endodontists, American Dental Association, and the Wisconsin Dental Association. I am currently working on the final stage of the endodontic board certification.

passion for saving teeth motivated me to be an endodontist. The challenge of treating anxious patients and navigating different complex anatomy makes it even more rewarding.

Is your practice limited to endodontics?

My practice is limited to endodontics.

Results in endodontics are quick and very

When and why did you become a specialist?

I graduated from Marquette in 2013 and went on to specialize in endodontics. My 6 Endodontic practice

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PRACTICE PROFILE gratifying. I do work in conjunction with a periodontist and oral surgeon, which gives patients a better understanding of multispecialty treatment planning and the convenience of being treated in the same facility.

Do your patients come through referrals?

It is a completely referral-based practice; patients are referred through general practitioners and other specialists. Former and current patients also refer others, with few self-referrals.

How long have you been practicing, and what systems do you use?

I have been practicing endodontics since 2004 when I initially graduated from

dental school. Since my endodontic residency, my outlook toward endodontics has changed, and my practice has been limited to endodontics for the past 6 years (residency included).

I use an electronic apex locator, a ZEISS surgical microscope, and Schick 33 sensors for better clarity radiographs. Instrumentation is a combination of hand and rotary instruments, mainly rotary. My preferred systems are a combination of Brasseler USA® and Dentsply rotary instruments. Ultrasonics, System B™, and Calamus® are also part of my armamentarium. I do enjoy the Global® operating stool for enhancing ergonomics and better back support. In my practice, anxious patients have the option of nitrous oxide, which helps them relax and enables

me to do a good job. Better instrumentation and infrastructure have made endodontics very enjoyable. Addition of a CBCT has been a great asset and helped with diagnosis, treatment planning, and the procedure itself.

What training have you undertaken?

I have a BDS and MS in Oral Pathology in India and a DDS and MS in endodontics in the United States.

Who has inspired you?

Dr. Ken Hargreaves is a great inspiration in the field of endodontics and contributed immensely in pain research. Dr. Harmeet Walia is known for his invention of NiTi in root canal therapy; he was a passionate teacher and a quick-witted person. Drs. Sheila Stover and Lance Hashimoto inspired me to continue working hard and do my best.

Finally, my parents inspired me to work hard and taught me the value of honesty, integrity, and humility.

What is the most satisfying aspect of your practice?

Providing relief and comfort to patients who come in with a lot of pain. Treating each patient the way I would like to be treated myself.

Professionally, what are you most proud of?

I’m proud of enjoying a wonderful relationship with my patients, referring dentists, colleagues, and staff.

Operatory (above) and Sirona CBCT (right) 8 Endodontic practice

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PRACTICE PROFILE What do you think is unique about your practice?

Toothaches can be very painful. We offer early morning and after hours emergency times to ease patients’ pain. I love to talk to my patients and educate them about the procedures. My patients receive a follow-up call from me rather than my staff, which helps me connect well with my patients.

Enhanced magnification, better instruments, advent of newer irrigation devices, improved techniques, and CBCT are some important aspects that contribute to a brighter endodontic future.

What has been your biggest challenge?

My biggest challenge is when patients do not follow up with their general dentist for restorative in a timely way.

What would you have become if you were not a dentist?

I would have liked to be a teacher. I love to interact with people, explain, and simplify things. Moreover, teaching is a good source of constant learning.

What is the future of endodontics and dentistry?

The future of endodontics is bright and secure. It is an established treatment with a high success rate, aimed at saving infected natural teeth that would otherwise be extracted. Nothing can replace the feeling of masticating with one’s natural teeth.

Enhanced magnification, better instruments, advent of newer irrigation devices, improved techniques, and CBCT are some important aspects that contribute to a brighter endodontic future. Regenerative endodontics has also come up in a big way. The future of dentistry would involve more digitalization and painless dentistry.

What are your tips for maintaining a successful specialty practice?

Evidence-based dentistry with best possible care for patients is essential for a successful practice. Maintaining communication and a good relationship with the referring dentist is imperative. Having a welltrained supporting staff is absolutely essential for a successful practice.

manage them is what matters. Work hard, and do your best.

What is your advice to budding endodontists?

What are your hobbies, and what do you do in your spare time?

Endodontics is a precision science.

Patience and attention to detail are essential to endodontics. Don’t be disheartened by failure — instead learn from your mistakes.

Complications happen, but knowing how to

I love cooking, spending time with my family, my husband, and daughter, as well as staying active and traveling.

To reach Dr. Mehrotra, email toothendo@ gmail.com. EP

10 Endodontic practice

Top 10 favorites Dr. Anushree Mehrotra with her husband, Himanshu, and daughter, Ananya

1.

2.

3.

4.

5.

6.

7.

Patience Electronic apex locator ZEISS surgical microscope Schick 33 sensor Ultrasonics Global® operating stool Brasseler USA®; Dentsply rotary instruments 8. Sirona CBCT 9. System B™ and Calamus® for warm vertical compaction 10. Chlor-XTRA™ 6% sodium hypochlorite with surface modifiers

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CLINICAL

Endodontic retreatment: a conservative and predictable therapy Dr. Jorge Alberdi highlights the importance of endodontic retreatment for tooth conservation Abstract Endodontic retreatment is carried out in cases that previous endodontic therapies failed. The main cause of treatment failure is bacterial persistence within the root canal or coronal leakage after treatment. The key factor to achieving success should be to evaluate whether retreatment is viable from a pathological and restorative point of view. The literature reports a success rate ranging from 80% to 88% for endodontic retreatment; thus, it is a procedure with a predictable prognosis when well performed and, essentially, when there is a correct diagnosis. Prognosis will be affected by the type of previous treatment received by the tooth.

Numerous technologies such as operative microscope, CBCT, and ultrasound are available to help execute the different procedures that could demand this therapy. Overall, clinical procedures include crown removal and/or access through the crown; removal of pins or posts and other core materials; removal of gutta percha, silver cones, pastes, and in some cases, even separated instruments. The objectives of this review/clinical technique article are to describe some of the most common clinical situations that occur during endodontic retreatment and to highlight the importance of endodontic retreatment for tooth conservation.

Conclusions: Based on a correct endodontic and restorative diagnosis and continuing with an appropriate endodontic therapy — in this case retreatment — we can maintain a compromised tooth and achieve treatment success, not only through endodontics but also dentistry in general.

of Endodontists (AAE) as the “procedure to remove root canal filling materials from the tooth, followed by cleaning, shaping, and obturating the canals.” This procedure is indicated in teeth where previous endodontic treatment seems inadequate or has failed, or in cases of long-term exposure of root canal filling material to the oral environment leading to apical pathology related to coronal leakage.1 The main cause of initial treatment failure is bacterial persistence within the root canal, or coronal penetration and/or leakage after treatment.2 This would indicate that if the professional can disinfect the root canal system and achieve a tight seal both apically and coronally during retreatment, the success rate would considerably increase.

Given the anatomical complexity of the root canal system, the objective of endodontic therapy would be to reduce the bacterial load to levels compatible with host healing.3

Dentists and/or endodontists should be trained to establish a diagnosis from an endodontic and restorative perspective, encompassing not only an endodontic vision of the tooth to be retreated but also a restorative vision. This means that dentists and/ or endodontists should evaluate whether retreatment is viable from a pathological point of view and also consider whether the dental element will be structurally suitable for adequate restoration and fully functional in the oral environment after endodontic therapy.

As part of this diagnosis process, the tooth needs to be evaluated to rule out any vertical root fracture (VRF) that may be contributing to the endodontic failure that has presented.

Currently, an important tool in endodontics is cone beam computed tomography (CBCT). This technique allows the practitioner to perform a study of the tooth to be retreated in three dimensions (3D), before the

Introduction Endodontic retreatment is defined in the glossary of the American Association Jorge Alberdi, DDS, is a specialist in endodontics, and auxiliary professor at the Endodontic Department of the Dental School at Universidad del Salvador/Asociación Odontológica Argentina (USAL/AOA) in Buenos Aires, Argentina. He is Director of the Postgraduate Endodontic Course at Círculo Odontológico de Rosario (COR), Rosario, Argentina, and is in private practice in endodontics and restorative post-endodontics in Las Rosas, Santa Fe, Argentina. Dr. Alberdi is also director of the Operative Microscope in Endodontics postgraduate course at the Institute Troiano Dentistry, Rosario, Argentina.

12 Endodontic practice

Figures 1A-1D: 1A. Cast pin divided with cutting metal bur, avoiding the damage of remaining dental structure. 1B-C. Ultrasonic vibration of the parts to dislocate and remove the pins. 1D. Drilled pin removed applying ultrasonic vibration through the hole Volume 12 Number 1

CLINICAL actual treatment is initiated, and thus plan the treatment knowing the anatomical and/ or iatrogenic obstacles present.4 Additionally, this allows determination of a VRF that often is not evident on traditional radiographs and may be difficult to identify during the clinical exam. A thorough study of the case before the clinical procedure allows the practitioner to determine its prognosis with greater accuracy. Additionally, the ability to detect root fractures or situations that could condition the prognosis is very useful in determining whether to perform the procedure, and especially to be able to explain to the patient the risks and benefits of carrying out the treatment.

The literature reports a success rate ranging from 80% to 88% for endodontic retreatment, thus being a procedure with a predictable prognosis when well performed and, essentially, when there is a correct diagnosis.5 On the other hand, the prognosis will be affected by the type of previous treatment received by the tooth. For example, when there is a perforation or remaining fractured instrument fragment, among other situations, the chances of success will not be the same as if these disadvantages were not present, and the success rate may decrease to 47%.6 Overall, clinical procedures include maneuvers such as crown removal and/ or access through the crown; removal of anchoring elements such as pins and posts; and removal of gutta percha, silver cones, pastes, and in some cases, even the removal of fractured instruments from the canals. Once these maneuvers are done, access to the root canal system should be gained for cleaning, shaping, and finally obturating the canal system again.7,8 The operating microscope is noteworthy as an

instrument of great importance to address the different clinical complexities and situations mentioned previously, which occur during endodontic retreatment.9 In addition to these aspects, we know that if conditions are favorable, retreatment can be performed in a single operative session.10 Considering that the techniques for adhesive post-endodontic restorations have evolved and been refined in the past few years, we could even permanently seal the access cavity and place the post in the same session if the case warrants it. The main advantages of this procedure would be non-contamination after treatment during restorative procedures and, in turn, the reduction of possible procedural errors due to ignorance of the tooth’s internal anatomy by the dentist who did not perform the endodontic treatment.11 Finally, considering the advances in apical microsurgery and the high success rate — approximately 90% — surgical retreatment should be the treatment option prior to tooth extraction when retreatment cannot be performed by orthograde access, and other clinical factors favor maintenance of the tooth.12 The objectives of this study are to describe some of the most common clinical situations that occur during endodontic retreatment and to highlight the importance of endodontic retreatment for tooth conservation.

Ultrasonic post removal Although there are various mechanical systems for the removal of metallic posts, at present, the tendency is to perform the removal by ultrasonic vibration.8,13 The first thing we should consider in cases of metallic posts is to dislodge them — that is, to

Figures 2A-2C: 2A. Ultrasonic vibration performed in a counter-clockwise direction under constant irrigation to facilitate cast post removal. 2B. The post is trimmed every 1-2 mm, deepening into the corono-apical direction under continuous irrigation.

2C. Until reaching the gutta-percha filling 14 Endodontic practice

eliminate all types of post retention that may exist. Where possible, this should be done at the expense of the metal post and not the tooth remnant. On the other hand, it will depend on the type of post to be removed, regardless of the need to be cut or not. In the case of cast posts on multiradicular teeth anchored to more than one root, it is advisable to cut them with quality metal cutting carbide burs under magnification to avoid damaging the remaining dental tissue during this maneuver (Figure 1A). Cutting is essential for this type of post because root inclination and its multiple anchor points determine that there is no coronal space for the post to pass through if the post is not sectioned. Once the post is sectioned, vibration is performed on the different parts with ultrasonic tips under continuous irrigation until the post is removed (Figures 1B, 1C). Another technique reported in the literature to remove cast posts is to drill the post stump, applying ultrasonic vibration through the hole and thus achieving the removal of the element.14,15 To perform this technique, the posts should be parallel, in case there are more than one or, rather, uniradicular pins. This technique seems to be very effective, greatly reducing the pulling force necessary to remove this type of pin15 (Figure 1D). In the case of metallic prefabricated posts, once their coronal portion is exposed, ultrasonic vibration is performed in a counter-clockwise direction under constant irrigation to facilitate their removal (Figure 2A). Overall, these posts are removed more easily than cast posts. The post removal time would depend on the type of cement used when initially placed and post length, requiring longer times with longer posts.16 Contrary to what has been described about metal posts, in the case of esthetic fiber-reinforced composite posts (FRCPs), commonly known as fiber posts, removal can become more complex. Fiber posts consist of parallel fibers in a resin matrix, and removal is directed to progression to the apical extent of the post down the center of the post working between the fibers. Numerous ultrasonic tips have been designed for this purpose, and removal systems are available, which are usually kits sold for each brand.17,18 These kits are not always available; therefore, a universal technique for all FRCPs is that of wear by ultrasonic vibration under magnification. This technique is also described with diamond burs powered by high-speed handpieces, but currently the use of diamond-coated ultrasonic tips is considered safer. Magnification is important in this procedure to be able to visualize more clearly the edges of the post because the post-cement-dentin interface of FRCPs is very difficult to determine with the naked eye. Once the post is exposed and cut Volume 12 Number 1

CLINICAL

to the level of the canal orifice at the chamber floor, the post is trimmed every 1-2 mm, deepening into the corono-apical direction (Figure 2B) under continuous irrigation until reaching the gutta-percha filling (Figure 2C).

Refrigeration by means of irrigation in these procedures is of great importance because ultrasound generates a high temperature, and this is harmful for the dental and supporting tissues.8,13

Removal of root canal filling material Having removed the anchoring elements, we proceed to the removal of the filling material, which can be gutta percha, endodontic sealant, silver points, pastes, or any combination of these.

Silver points are root canal filling materials that were used decades ago, still in limited use, but there are currently still cases where they need to be removed. Silver cones are rigid and generally found with some degree of canal mismatch because they are thin, round-shaped, and have a low taper tend to have greater volume of sealer to cone in the canal. Generally, a remnant of these cones is present in the coronal chamber, allowing the practitioner to grasp and remove them with thin tweezers. Additionally, the use of ultrasound to dislodge them, if they are attached to the canal, may be beneficial.

This would favor their removal, but on the other hand, they are very fragile. In the presence of excessive ultrasonic vibration or some milling, they may break and become trapped within the canal, complicating their removal. A hand file may be threaded down the side of the silver point, and after penetration several millimeters into the canal, a tug on the file may engage the silver point and dislodge it from the canal. When silver points were used, an amalgam was prepared as a coronal obturation, covered many times by a cast crown. The amalgam should be removed using only rotating burs to break it, then following carefully with ultrasound so as not to make the mistake of cutting the silver cones at the canal opening (Figure 3A).

In general, root canals are usually filled with gutta percha when patients attend the dental clinic. Gutta percha is a thermoplastic material; therefore, there are different techniques for its removal. The traditional technique uses K files or H files, along with chemical solvents such as xylol or chloroform to soften the gutta-percha component of the obturation material, allowing further penetration of the file deeper into the canal. The procedure begins from the crown to the apex, using copious irrigation with a physiological solution and/or sodium hypochlorite along with the removal. Gates burs can be used for the coronal and middle thirds in root canals Volume 12 Number 1

Figures 3A-3D: 3A. Silver points removal under careful ultrasonic vibration. 3B. Gutta-percha removal under continuous motion ProTaper Retreatment System. 3C. Reciprocation motion WaveOne system. 3D. Ultrasonic removal of gutta percha

with very compact fillings. Later, together with mechanized endodontics, different brands of gutta-percha removal systems have emerged. All function in the same way, generally using rotational movement (Figure 3B). Currently, WaveOneÂŽ (Dentsply Maillefer, Switzerland) and ReciprocÂŽ (VDW, Germany) instruments, of reciprocating motion, have also been suggested to remove gutta percha with very good results reported in the literature19 (Figure 3C). In any case, and considering these varied possibilities, a recommended technique would be to use mechanized systems to remove most root filling material without solvent, and then finish the apical portion or curvatures manually with solvent if necessary.20 Although the use of solvents facilitates the procedure by softening the gutta percha, on the other hand, gutta-percha sticks to the root canal walls, hindering its complete elimination at times.

Residual solvents may hamper contact of the new obturation material (sealer and gutta percha) potentially creating a potential leakage avenue over time. Therefore, its use is recommended only when essential.

Currently, the use of ultrasound under magnification is proposed for removing remnants of filling material within the canal and optimizing its cleaning (Figure 3D).

the presence of the middle mesial canal of the mandibular first molar can be the cause of missed anatomy that leads to the failure of the initial endodontic treatment (Figure 4A). Of all reported cases, the middle mesial canal is the least common.21,22 To determine the presence of these missed canals during diagnosis, when they cannot be clearly visualized in a periapical radiograph, the use of tomography again becomes an important tool in the exploration of these canals and their discovery4,23 (Figure 4B). One of the most common causes of missed canals is MB2. This canal is present in a percentage of cases ranging from 55% to 70% and even up to 80% of cases, according to different authors24,25 Regardless of these numbers, it is striking that the discovery rate of this canal is greater in retreatment than in the initial treatment.26 This could be due to the fact that, in the face of initial treatment failure and while searching for its cause, the dedication of the acting professional to find the root canal is greater (Figure 4C). Another important factor to consider regarding the MB2 canal is that in 39% of cases, it ends in an independent foramen.24 In these cases, the use of tomography can also guide in discovering them and determining their location, to allow planning their search in a predictable manner.4,27

Missed root canals

Removal of fractured instruments

Many times, the cause of initial treatment failure is the presence of bacteria in some missed canals. The most common cases are the second mesiobuccal canal (MB2) of the maxillary first molar, the presence of two canals in the maxillary second premolar, two canals in the lower incisors and premolars, and the presence of two distal canals in the mandibular molars. Rarely, although possible,

In cases of non-surgical retreatment, one of the most complex situations to solve is the removal of fractured instruments from within the canal (Figure 4D). Numerous techniques have been described, from the use of hand files to trap and remove the fragments to countless devices made for this purpose.28 Regarding the use of these specific kits, it is interesting to note that each operator should Endodontic practice 15

CLINICAL choose the one considered most appropriate to his/her training.

A universal technique is the use of thin ultrasonic tips under magnification, preferably an operating microscope. The first thing we should achieve is straight access to the instrument to be removed. The technique consists of exposing the instrument from 1 mm to 3 mm in its most coronal portion to be able to perform ultrasonic vibration in that place, thus unlocking the fragment and removing it. The exposed length will also depend on the length of the fragment.

This procedure takes time and has to be performed carefully because the space generated to dislodge the fragment is at the expense of dental tissue, structurally weakening the root. This situation can also lead to accidents such as perforations, in the case of not having good vision and fine and precise motion. Therefore, this maneuver should be as conservative as possible.29 Some factors will determine whether to remove the fractured fragment. First, its position in the root canal is essential, considering that the more apical the fragment, the more difficult its

removal. Additionally, if the instrument is beyond the curvature of the canal or is not visible, the possibilities decrease from few to none, increasing the risk of complications.30

Treatment of root perforations Root perforations are mistakes often made during endodontic treatment. Root perforations can occur at different levels, and we could classify them didactically according to their location as occurring in the apical third, middle third, coronal third, or chamber floor. In the apical third, perforations usually occur when there is a ledge, and we try to negotiate the canal; in that attempt, a hole is drilled in the canal, transporting the canal.

Perforations can also occur when trying to remove fractured instruments as described previously. In the middle third, the cause is usually due to deviations in post preparation, or in some cases, as in the mesial roots of mandibular molars, it can also be due to excessive wear of the furcal wall during instrumentation-stripping related to the natural concavity on the distal aspect of the mesial root. In the coronal third, perforations

usually occur during post preparation or due to errors when accessing the canal in the initial stages of endodontic treatment. The same happens with chamber floor perforations, generally related to a spatial disorientation by the operator when approaching the pulp chamber and searching for the canal opening, which is even greater in cases of very sclerotic pulp chambers due to secondary dentin formation. An important prognostic factor with respect to the perforation site is related to the level of the surrounding bone, whether it is above or below the crestal bone level. Perforation size is also important, being inversely related to the prognosis, and an additional important factor is if the perforation is recent or longstanding.31 Regarding the perforation site, if perforations are above the level of the crestal bone, permanent sealing is more complex, considering that they are practically exposed to the oral environment. In these cases, the materials of choice are usually glass ionomers or composite resins. On the other hand, in cases of perforations below the crestal bone or chamber floor levels, the material of choice is mineral trioxide aggregate (MTA), with many years of studies on this matter.32-34 The use of new bioceramics materials is also currently suggested.35 In the case of chamber floor perforations, which are usually the most common, it is important to consider at the time of diagnosis whether they are recent or longstanding. The difference if they are longstanding is that they usually have an associated osseous lesion. Treatment in these cases begins with curettage of the granulation tissue occupying the space of the osseous lesion with excavators or ideally with electrocautery/lasers. The edges of the perforation are then cleaned with ultrasound because they are probably contaminated.

And finally, in these cases, before placing MTA into the perforation site, it is optional to place a collagen membrane or similar in the space of the lesion, as is the use of calcium hydroxide, in order to generate a barrier preventing extrusion of the MTA repair material.36 Use of the barrier membrane limits excess repair material from extruding into the space left by the osseous lesion and allow osseous healing with bone fill over time.

Discussion

Figures 4A-4D: 4A.Presence of the middle-mesial canal in a young mandibular first molar. 4B. The use of CBCT becomes an important tool in the exploration of canals and their discovery. 4C. Independent foramen MB2 canal missed in primary treatment. 4D. Separated file removal from canal with ultrasonic thin tip and under operative microscope 16 Endodontic practice

Endodontic retreatment, in either an orthograde or retrograde direction according to the case, should be the option of choice before tooth extraction and implant placement when the tooth is structurally sound and periodontal conditions warrant maintenance of the tooth. Numerous procedures described in this study were analyzed in Volume 12 Number 1

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Volume 12 Number 1

should be carefully read and understood so as not to be influenced by results that may not be appropriate. Both therapies, correctly chosen and carried out, are intended to return the patient’s health along with masticatory function and esthetics. It is inadequate to analyze them as competing procedures — endodontics versus implant; they should be considered complementary procedures to restore the patent’s oral health.43

Conclusions Based on a correct endodontic and restorative diagnosis and continuing with appropriate endodontic therapy — in this case retreatment — we can maintain a compromised tooth and achieve treatment success, not only through endodontics but also dentistry in general. An adequate coronal restoration and routine follow-ups are essential to evaluate the long-term success of our therapies.

Acknowledgment: Dr. Alberdi extends his appreciation to Dr. Fernando Goldberg for his guidance in the writing of this manuscript. EP REFERENCES 1. American Association of Endodontists. Glossary of Endodontic Terms. 2016. http://www.aae.org/clinicalresources/aae-glossary-of-endodontic-terms.aspx.

Accessed November 19, 2018.

2. Ricucci D, Siqueira JF Jr, Bate AL, Pitt Ford TR. Histologic investigation of root canal-treated teeth with apical periodontitis. A retrospective study from twenty-four patients.

J Endod. 2009;35(4):493-502.

3. Siqueira JF Jr, Roças IN. Clinical implications and microbiology of bacterial persistence after treatment procedures.

J Endod. 2008,34(11):1291-1301.

4. AAE and AAOMR Joint Position Statement: Use of Cone Beam Computed Tomography in Endodontics 2015 Update.

J Endod. 2015;41(9):1393-1396.

5. Imura N, Pinheiro ET, Gomes BP, et al. The outcome of endodontic treatment: a retrospective study of 2000 cases performed by a specialist. J Endod. 2007;33:1278-1282.

6. Gorni FG, Gagliani MM. The outcome of endodontic retreatment: a 2-yr follow-up. J Endod. 2004;30(1):1-4.

7. Goldberg F, Cantarini C. El retratamiento endodóntico: consideraciones clínicas. Rev Asoc Odontol Argent. 2014; 102(2):76-82.

8. Ruddle CJ. Nonsurgical Retreatment. J Endod. 2004;30(12): 827-845.

9. AAE Special Committee to Develop a Microscope Position Paper. AAE Position Statement. Use of microscopes and other magnification techniques. J Endod.

2012;38(8):1153-1155.

10. Moreira MS, Anuar ASN, Tedesco TK, Dos Santos M, Morimoto S. Endodontic treatment in single and multiple visits: an overview of systematic reviews. J Endod.

2017;43(6):864-870.

11. Schwartz RS, Fransman R. Adhesive dentistry and endodontics: materials, clinical strategies and procedures for restoration of access cavities: a review. J Endod.

2005;31(3):151-165.

12. Kim S, Kratchman S. Modern endodontic surgery concepts and practice: a review. J Endod. 2006;32(7):601-623.

13. Plotino G, Pameijer CH, Grande N, Somma F. Ultrasonics in endodontics: a review of the literature. J Endod.

2007;33(2):81-95.

14. Zuolo ML, Kherlakian D, de Mello JE Jr, de Carvalho MCC, Fagundes MIRC. Reintervención en Endodoncia. Sao Paulo, Brazil: Santos Editora; 2012.

15. Graça IAA, Sponchiado Júnior EC, Marques AAF, de Moura Martins L, Garrido ÂDB. Assessment of a cavity to optimize ultrasonic efficiency to remove intraradicular posts. J Endod.

2017;43(8):1350-1353.

16. Ebrahimi Dastgurdi M, Khabiri M, Khademi A, Zare Jahromi M, Hosseini Dastnaei P. Effect of post length and type of luting agent on the dislodging time of metallic prefabricated posts by using ultrasonic vibration. J Endod.

2013;39(11):1423-1427.

17. Scotti N, Bergantin E, Alovisi M, Pasqualini D, Berutti E.

Evaluation of a simplified fiber post removal system. J Endod. 2013;39(11):1431-1434.

18. Lindemann M, Yaman P, Dennison JB, Herrero AA. Comparison of the efficiency and effectiveness of various techniques for removal of fiber posts. J Endod. 2005;31(7):520-522.

19. Colaco AS, Pai VAR. Comparative Evaluation of the Efficiency of Manual and Rotary Gutta-percha Removal Techniques. J Endod. 2015; 41:1871–1874.

20. Colaco AS, Pai VAR. Comparative evaluation of the efficiency of manual and rotary gutta-percha removal techniques. J Endod. 2015;41(11):1871-1874.

21. Nosrat A, Deschenes RJ, Tordik PA, Hicks ML, Fouad AF. Middle mesial canals in mandibular molars: incidence and related factors. J Endod. 2015;41(1):28-32.

22. Tahmasbi M, Jalali P, Nair MK, Barghan S, Nair UP. Prevalence of middle mesial canals and isthmi in the mesial root of mandibular molars: an in vivo cone-beam computed tomographic study. J Endod. 2017; 43(7):1080-1083.

23. Michetti J, Maret D, Mallet JF, Diemer F. Validation of cone beam computed tomography as a tool to explore root canal anatomy. J Endod. 2010;36(7):1187-1190.

24. Briseño-Marroquín B, Paqué F, Maier K, Willershausen B, Wolf TG. Canal morphology and configuration of 179 maxillary first molars by means of micro-computed tomography: an ex vivo study. J Endod. 2015;41(12):2008-2013.

25. Wolcott J, Ishley D, Kennedy W, Johnson S, Minnich S. Clinical investigation of second mesiobuccal canals in endodontically treated and retreated maxillary molars. J Endod. 2002;28(6):477-479.

26. Wolcott J, Ishley D, Kennedy W, et al. A 5 yr clinical investigation of second mesiobuccal canals in endodontically treated and retreated maxillary molars. J Endod. 2005; 31(4):262-264.

27. Hiebert BM, Abramovitch K, Rice D, Torabinejad M. Prevalence of second mesiobuccal canals in maxillary first molars detected using cone-beam computed tomography, direct occlusal access, and coronal plane grinding. J Endod.

2017;43(10):1711-1715 28. Terauchi Y, O’Leary L, Kikuchi I, et al. Evaluation of the efficiency of a new file removal system in comparison with two conventional systems. J Endod. 2007;33(5):585-588.

29. Terauchi Y, O’Leary L, Suda H. Removal of separated files from root canals with a new file-removal system: case reports. J Endod. 2006;32(8):789-797.

30. Souter NJ, Messer HH. Complications associated with fractured file removal using an ultrasonic technique. J Endod.

2005;31(6):450-452.

31. Tsesis I, Rosenberg E, Faivishevsky V, et al. Prevalence and associated periodontal status of teeth with root perforation: a retrospective study of 2,002 patients’ medical records. J Endod. 2010;36(5):797-800.

32. Pontius V, Pontius O, Braun A, Frankenberger R, Roggendorf MJ. Retrospective evaluation of perforation repairs in 6 private practices. J Endod. 2013;39(11):1346-1358.

33. Torabinejad M, Chivian N. Clinical applications of mineral trioxide aggregate. J Endod. 1999;25(3):197-205.

34. Parirokh M, Torabinejad M. Mineral trioxide aggregate: a comprehensive literature review—Part I: chemical, physical, and antibacterial properties. J Endod. 2010;36(1):16-27.

35. Torabinejad M, Parirokh M, Dummer PMH. Mineral trioxide aggregate and other bioactive endodontic cements: an updated overview—Part II: other clinical applications and complications. Int Endod J. 2018;51(3):284-317.

36. Pace R, Giuliani V, Pagavino G. Mineral trioxide aggregate as repair material for furcal perforation: case series. J Endod.

2008;34(9):1130-1133.

37. Iqbal MK, Kim S. A review of factors influencing treatment planning decisions of single-tooth implants versus preserving natural teeth with nonsurgical endodontic therapy. J Endod. 2008;34(5):519-529.

38. Khalighinejad N, Aminoshariae A, Kulild JC, et al. Effect of the dental operating microscope on the outcome of nonsurgical root canal treatment: a retrospective case-control study. J Endod. 2017;43(5):728-732.

39. Gomes AC, Nejaim Y, Silva AIV, et al. Influence of endodontic treatment and coronal restoration on status of periapical tissues: a cone-beam computed tomographic study. J Endod. 2015;41(10):1614-1618.

40. Craveiro MA, Fontana CE, de Martin SA, Bueno CE. Influence of coronal restoration and root canal filling quality on periapical status: clinical and radiographic evaluation. J Endod. 2015;41(6)836-840.

41. Ng YL, Mann V, Gulabivala K. A prospective study of the factors affecting outcomes of nonsurgical root canal treatment: part 1: periapical health. Int Endo J. 2011;44(7):583-609.

42. Ng YL, Mann V, Gulabivala K. A prospective study of the factors affecting outcomes of nonsurgical root canal treatment: part 2: tooth survival. Int Endod J. 2011;44:610-625.

43. Setzer FC, Kim S. Comparison of long-term survival of implants and endodontically treated teeth. J Dent Res. 2014;93(1):19-26.

44. Hannahan JP, Eleazer PD. Comparison of success of implants versus endodontically treated teeth. J Endod.

2008;34(11):1302-1305.

45. Doyle SL, Hodges JS, Pesun IJ, Baisden MK, Bowles WR. Factors affecting outcomes for single-tooth implants and endodontic restorations. J Endod. 2007;33(4):399-402.

Endodontic practice 17

CLINICAL

order to perform endodontic retreatment.

Dental implants are the ideal alternative to replace a tooth that cannot be treated, and they have a good prognosis. It is for this reason that, before making the decision to perform tooth extraction, the dentist/ endodontist should perform a multidisciplinary evaluation.37 The use of technology in endodontic retreatment, such as the use of CBCT for diagnosis and magnification in dental clinical practice, allows us to perform procedures that are more predictable. The clinical procedure of endodontic retreatment under the operating microscope allows us to deal with highly complex cases and improve the scope of our treatment and its prognosis, always with the help of adequate operator training.9,38 In addition, ultrasound becomes an instrument of great utility in most stages of endodontic therapy, especially nonsurgical and surgical retreatment.13 Once the tasks of removing anchors and obturation materials, sealing of perforations, etc., are completed, shaping and disinfection of the root canal are essential to be able to re-seal it properly. Depending on the clinical criteria of the operator, the placement of a new post or final restoration is recommended to avoid contamination of the retreated root canals.10 An adequate coronal seal is essential to prevent coronal leakage and achieve the success of our therapies — that is, the health of the periradicular periodontium.39,40 Although the coronal seal improves the prognosis of retreatment, other factors affecting it could be the size of the previous periradicular lesion, the presence of perforations, or the impossibility of achieving an apical seal, among others.41 According to a review

by Ng, et al., the 4-year survival rate was similar between initial treatment and retreatment, reaching 95%.42 Tooth maintenance implies preserving the periodontium, which results in preserving bone and gingival levels, which have a great esthetic value in dentistry these days. Many times, tooth extraction may be a simpler alternative than endodontic retreatment, but that should not be the reason for the decision.43 In regard to making a referral or making the decision to maintain or replace a dental element, it is very important that general dentists know the possibilities of current endodontic treatment and its benefits.44,45 The success of a dental implant or an endodontic treatment depends in turn on the experience of the operator; this means that statistics and published review studies in both specialties may not always reveal the current reality of the specialty. It is for this reason that publications in this regard

CASE STUDY

Bioceramic liner material: bridging the gap between bioceramics and restorative materials Dr. Allen Ali Nasseh discusses a new bioactive, dual-cure liner

O

ver 10 years ago, premixed nanoparticulate bioceramic cements were introduced to endodontics. These were second-generation bioceramic compounds inspired by mineral trioxide aggregate (MTA), which had exhibited excellent biocompatibility and sealing ability since its release 15 years earlier.1,2 This next generation of bioceramics demonstrated improved clinical handling properties with less dentinal staining compared to their MTA predecessor.3,4 Furthermore, the smaller particle size of these bioceramics allowed development of different formulations with varied viscosities in order to improve clinical handling of the material. This provided a range of clinical uses spanning from root canal sealer all the way to perforation repair and retrofilling after apicoectomy procedures.5 The versatility of applications offered by the calcium silicate bioceramics has been ideal for clinical endodontics.3-5 The long setting time, ranging from 1 to 4 hours, combined with their excellent clinical handling properties allow easy, no-rush surgical and nonsurgical treatment. However, in applications where a final restoration needs to interface with the bioceramic cement, a second appointment has been required in order to allow ample time for the bioceramic layer to achieve final set (Figures 1A-1D). This

Allen Ali Nasseh, DDS, MMSc, received his dental degree from Northwestern University Dental School in Chicago, Illinois, in 1994 and completed his postdoctoral endodontic training at Harvard School of Dental Medicine in 1997, where he also received a Masters in Medical Sciences (MMSc) degree in the area of bone physiology.

He has been a clinical instructor and lecturer in the postdoctoral endodontic program at Harvard School of Dental Medicine since 1997 and the Alumni Editor of Harvard Dental Bulletin. Dr. Nasseh is the endodontic advisor to several educational groups and study clubs and is endodontic editor to several peer-reviewed journals and periodicals. He has published numerous articles and lectures extensively nationally and internationally in surgical and nonsurgical endodontic topics. Dr. Nasseh is in solo private practice (MSEndo.com) in downtown Boston, Massachusetts.

Disclosure: Dr. Nasseh is the President and Chief Executive Officer for the endodontic education company Real World EndoÂŽ (RealWorldEndo.com).

Disclosure: Dr. Nasseh helped develop this product for Brasseler USA.

18 Endodontic practice

Figure 1: 1A. Following a floor perforation, 1B. a pure bioceramic like BC Putty (Brasseler USA, Savannah Georgia) is used to seal the furcation floor. 1C. But since the BC Putty takes about 1 hour to set, a wet cotton pellet is placed on top of it, and second appointment is made. During the second appointment, 1D. the cotton and provisional are removed, and a final restoration is placed on top of the bioceramic

rule has even been extended to calcium carbonate-based bioceramics that take up to 2 weeks for their final set.6 This long final set is a hallmark of all pure bioceramics and has been an inconvenience to both the patient and the operator and a place where improvements were deemed necessary. Recently, a new bioactive, dual-cure liner has been developed by our team that promises to bridge the gap in this specific application.

The purpose of the new BC-Liner (Brasseler USAŽ, Savannah, Georgia) is to cover the freshly placed bioceramic repair material to provide isolation and protection for the material while it’s setting. Meanwhile, the liner can act as a more compatible surface to bond the final restoration material. Furthermore, endodontic work can continue immediately after coverage of the bioceramic with the dual-cure liner without the fear of the bioceramic washing out. In this case, the bioceramic liner is acting as an interface between the bioceramic repair material and the restorative material (Figure 2).

Whenever a resin component is present in a root repair material, you can expect its

Figure 2: The use of BC-Liner allows immediate restoration after a bioceramic is used to repair a perforation. A thin layer of BC Liner is placed immediately over the bioceramic layer, is light-cured, and then the final restoration is bonded to it immediately.

biocompatibility to be lower than a pure bioceramic. Pure bioceramic formulations devoid of any resin components are therefore more biocompatible and better suited for situations when a barrier material is to interface with pulpal or periodontal cells.

This biocompatibility advantage is especially important during perforation repairs and pulpcapping procedures where the barrier material interactions with cells should not induce additional inflammation. This is why the liner Volume 12 Number 1

CASE STUDY

Figure 3: A pure bioceramic would provide the most biocompatibility when interfacing with cells. This can be pulpal cells during pulp capping procedures or pulpotomies, or PDL cells during perforation repairs

Figure 4: ParaPost® post perforation and symptomatic abscess formation in the mesial aspect of this mandibular first molar in a young patient. The crown was also restored with ill-fitting distal margins

Figure 6: 6A. Following isolation of the post, ultrasonics were used to break the cement interface between the tooth and the post and remove the post through the crown. 6B. The post was removed through the crown

Figure 8: After drying the perforation site, BC Putty was used to incrementally fill the entire post perforation site up to the cementoenamel junction (CEJ)

is not designed to be placed directly over the cell baring surface, but instead to act as an interface between the more biocompatible pure bioceramic and the final restorative material. Therefore, in such application, the pure bioceramic barrier seals the defect and is in contact with cells for the most biocompatibility (Figure 3). The defect itself is not sealed with the liner, but the liner would be a good interface between the unset pure bioceramic and the final restorative material. This Volume 12 Number 1

technique is developed to help combine the advantages of pure bioceramics with bioactive hydrophilic resin compomers. (Editor’s note: Compomers is defined as materials that combine the benefits of composites and glass ionomers.) In this version of the “Lid Technique,”6 a pure bioceramic is used for pulp capping or perforation repair material directly over cells, followed by placing a layer of resin containing bioactive liner on top of it as “a lid.” A final restoration is then bonded

Figure 5: A minimally invasive and focused access was made through this CAD/CAM-designed crown using a round diamond

Figure 7: Following cleaning of the access and removal of all cement. Clean dentin was isolated surrounding the perforation site, and the space was disinfected using NaOCI under negative pressure

to the liner to complete the procedure. This technique allows the liner to act as an interface between the pure bioceramic and the final restoration, allowing the benefits of both pure bioceramics and dual-cure bioactive material to help improve the clinical efficiency of the procedure to a single appointment.

The following clinical case demonstrates this technique. A young female patient had recent root canal therapy, post and core, and crown by her restorative dentist before the tooth became symptomatic. A consultation radiograph revealed a large post perforation that had gone unnoticed during treatment!

(Figure 4). The options of extraction versus an attempt at saving the tooth through post retrieval and perforation repair were explained. An access was made through the intact crown (Figure 5), and the post was isolated and removed (Figures 6A-6B).

Once the post was removed, the perforation was isolated through the access. Some gutta percha from around the perforation site was removed until a rim of clean dentin was observed around the perforation site.

The space was adequately disinfected using negative pressure and 5.25% NaOCI and dried (Figure 7). The post space was then filled with the pure bioceramic, BC Endodontic practice 19

CASE STUDY

Figure 9: 9A. Immediately after BC Putty placement, the remainder of the chamber was filled with the new BC-Liner (Brasseler USA, Savannah Georgia). 9B. and was light-cured

Putty™ (Brasseler USAŽ, Savannah Georgia) incrementally, for the entire length of the post space. (Figure 8). At this point, the unset BC Putty constituted the floor of the access.

Previously, placement of a final restoration would not have been possible under these circumstances, as etching and bonding to this material would not have been possible.

However, in this case, if a final restoration was to be placed immediately after this repair procedure, a 2 mm-3 mm layer of BC-Liner (Brasseler USA, Savannah, Georgia) would have been placed against the BC Putty, light-cured, and the remainder of the access cavity would have been etched, bonded, and filled with the restorative material of choice.

In this case, however, the remaining space was filled with BC-Liner all the way up to the cavosurface margin of the crown, and it was light-cured in place (Figures 9A-9B).

This was due to the determination of the poor quality of the crown, which required replacement as soon as the salvageability of this tooth was determined. Therefore, the liner was used in this case as a long-term provisional and filled the entire access space over the BC Putty repair material until the fate of the tooth was determined (Figure 10). This was done instead of a material like Cavit™ (3M, St. Paul, Minnesota) that has poor longterm seal.

If the crown did not require replacement, the restorative dentist could have drilled for a depth of about 3 mm into the opacious whiteshade liner and used it as base to bond a final restoration in place. The opacious white shade of this material is deliberately designed to create contrast against dentin in order to facilitate selective removal of the material if later needed.

The postoperative radiograph (Figure 10) shows the case after post removal and perforation repair, BC Putty repair, and BC Liner repair on top of the material to seal the access (Figure 11). The patient was referred 20 Endodontic practice

Figure 10: The immediate post-op radiograph shows the repaired perforation site with the BC Putty and the access area filled with the BC-Liner. The original poor distal seal from the crown is visible

Figure 11: The opacious white BC-Liner used as a provisional directly over the BC Putty perforation repair material and sealing the access as a provisional until the crown is replaced

back to her restorative dentist for an observation period of 12 weeks, followed by crown replacement if symptoms are resolved. The patient was followed up for a 6-month postoperative follow up visit after a new crown had been fabricated and all symptoms had been resolved (Figures 12A-12B). This case showcases the combined use of a pure bioceramic putty against a new dual cure bioactive liner optimized to use with bioceramic compounds. This post-perforation repair case was completed in a single visit as a result of this synergy.

According to its distributor, BC-Liner (Brasseler USA, Savannah Georgia) has a compressive strength of 280MPa, flexural Strength of 97MPa, a self-cure time of 3-10 minutes and a light-cure time of 20 seconds using low-energy curing lights.7 These attributes help this material provide an optimal flexural and compressive strength as a liner, and its chemistry optimizes its use as a protective barrier over a bioceramic. The material itself is a bioactive, dual-cure, hydrophilic resin

with ionomer glass particles, and rubberized resin components that help improve fracture resistance under shear forces and loading required by the final restoration.

The use of this material in a perforation repair is also shown in this perforation model of a premolar tooth with a size 4 round bur buccal root perforation (Figure 13). In this case, the pure bioceramic BC Putty is used once again as the ideal material against the PDL cells (Figure 14). Previously, cotton and Cavit had to be used and a second appointment scheduled to allow the bioceramic material to set. By applying the BC Liner immediately against the putty and light-curing it, the operator can complete the perforation repair in a single visit and continue with the access preparation and root canal therapy without fear of the putty washing out (Figure 15).

An important point of consideration for successful implementation of this Bioceramic and Liner Lid Technique in perforation repairs and pulp capping procedures is paying particular attention to extending the Volume 12 Number 1

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Figure 12: Six months’ postoperative recall shows 12A. Healing in the furcation and bone formation against the repair material. 12B. The lack of deep probing and periodontally healthy tissues

Figure 13: A round bur size 4 perforation on the buccal aspect of this model tooth for demonstration of the lid technique perforation repair procedure

Figure 14: The BC Putty is used to repair the perforation interfacing the pure bioceramic against the PDL cells for maximum biocompatibility

liner beyond the border of the bioceramic and into the clean dentin for a minimum of 1 mm-2 mm. This is where the bond to dentin will seal the underlying bioceramic from exposure to liquids on the other side and prevents washout. Furthermore, this provides a stronger bond to the dentin. Therefore, the area beyond the margin of the repair material should be thoroughly cleaned prior to the application of the repair material which should in turn be applied to the application site carefully and without much smearing.

Any smearing beyond the margins should be cleaned by microbrushes and gentle water stream or the liner material applied beyond that area into clean dentin. Application of the liner borders into clean dentin is important to provide an adequate “lid” and a completely sealed environment for the underlying repair material. Furthermore, since the BC Liner material is a bioactive, self-etching hydrophilic resin with ionomer glass, it’s important

to allow a few seconds of rest after application of the material to the site in order for the material to self-etch the dentin prior to lightcuring. Limiting the light-curing process to a short few seconds and only to the surface of the liner while allowing the bulk of the material to self-set will further limit polymerization shrinkage in this class of materials.

In summary, the introduction of the BC-Liner as a class of dual-cure bioactive materials optimized to interact with the bioceramic materials and the introduction of a technique that uses the liner as a protective layer over the bioceramic have the potential to further improve the efficiency of care in perforation repairs and pulp capping procedures that require immediate sealing of the defect with the most biocompatible procedure and the restoration of the defect or access with a final restoration at the same appointment. In such cases, the uses of a bioactive liner such as the BC-Liner material is advantageous as

22 Endodontic practice

Figure 15: A layer of BC-Liner is used immediately over the BC Putty to protect it during the long setting time. At this point, access procedures and root canal therapy can either continue without fear of displacing the putty material, or the access can be sealed with a permanent material if desired

it interfaces between bioceramics and restorative materials bridging the gap between these two incompatible and yet uniquely useful materials. EP

References 1. Tawil PZ, Duggan DJ, Galicia JC. Mineral trioxide aggregate (MTA): its history, composition, and clinical applications.

Compend Contin Educ Dent. 2015;36($):247-52.

2. Lee SJ, Monsef M, Torabinejad M. Sealing ability of a mineral trioxide aggregate for repair of lateral root perforations. J Endod. 1993;19(11):541-544.

3. Silva Almeida LH, Moraes RR, Morgental RD, Pappen FG. Are premixed calcium silicate–based endodontic sealers comparable to conventional materials? A systematic review of in vitro studies. J Endod. 2017;43(4):527-535.

4. Keskin C, Demiryurek EO, Ozyurek T. Color stabilities of calcium silicate-based materials in contact with different irrigation solutions. J Endod. 2015;41(3):409–411.

5. Haapasalo M, Parhar M, Huang X, Wei X, Lin J, Shen Y. Clinical use of bioceramic materials. Endod Topics.

2015;32(1):97-117.

6. Nasseh AA, Brave D. Apicoectomy: The Misunderstood Surgical Procedure. Dent Today. 2015 Feb;34(2):130, 132, 134-136.

7. Internal studies by manufacturer.

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Use of cone-beam computed tomography and ultrasound for the removal of gutta-percha extruded into the maxillary sinus Drs. Clovis Monteiro Bramante, Jussaro Alves Duque, Murilo Priori Alcalde, Victor de Moraes Cruz, Alexandre Silva Bramante, Talita Tartari, Braulio Pasternak Jr, Cesar Augusto Pereira Oliveira, and Marco Antonio Hungaro Duarte discuss helpful tools to aid in the planning of endodontic surgeries Abstract One type of accident that can occur during endodontic treatments is the overextension of gutta percha to periapical tissues, which could necessitate surgical intervention. The purpose of this article is to describe endodontic surgery in the apical region of the maxillary premolar. Radiography showed extrusion of the gutta-percha cone from the apex of the palatal root. A cone beam computed tomography (CBCT) scan confirmed that the extruded material was inside the maxillary sinus. The CBCT scan also was used to assist in surgical planning. During the surgical management of the patient, an osteotomy was performed employing an ultrasonic insert to provide access to the maxillary sinus, and gutta percha was removed. At the 12-month follow-up, both clinical and radiographic exams showed adequate healing. The CBCT proved to be an excellent tool to aid in planning endodontic surgeries. Use of an ultrasonic insert in the osteotomy demonstrated to be a safer alternative.

master cone.2-4 When gutta percha goes beyond the foramen, the prognosis is unfavorable once it can act as a foreign body and contribute to the formation or maintenance of an apical lesion and can lead to postoperative complications such as chronic inflammation.5,6 Thus, it is necessary to remove the extravasated material, which is a challenge since it is performed through the canal, and in many situations, a fragment may remain in the periapical tissues.7 Surgical intervention is a solution to this problem. However, there are several factors to take into consideration during the surgery, such as the relationship between the tooth and anatomical structures such as the maxillary sinus. In these cases, cone beam computed tomography (CBCT) is an excellent tool for diagnosis, including localization

of extruded materials into the adjacent anatomic structures,8,9 and surgical planning.9 The CBCT scan will show if there is involvement of the maxillary sinus, provide the relation of the root apices with the neighboring structures, and help to establish the site where the osteotomy should be done to perform a minimally invasive surgery.10,11 A conventional technique to access the area of interest during surgery is the use of manual and rotary instruments. However, this technique can cause thermal injury to the bone and other adjacent structures.12 An alternative to traditional techniques is the use of ultrasound for osteotomies. The advantages of this method include the selective cut of mineralized tissue without damaging the adjacent soft tissue and without generating heat, better visualization

Introduction The extrusion of filling material is a type of accident that can occur during endodontic treatments1,2 due to factors such as apical root resorption, overinstrumentation, destruction of the apical constriction, inadequate preparation of the apical stop, or the use of undersized the gutta-percha

Clovis Monteiro Bramante, MSc, PhD, Jussaro Alves Duque, MSc, Murilo Priori Alcalde, MSc, PhD, Victor de Moraes Cruz, MSc, Alexandre Silva Bramante, MSc, PhD, Talita Tartari, MSc, PhD, and Marco Antonio Hungaro Duarte, MSc, PhD, are from the Department of Endodontics, Dental School of Bauru, University of São Paulo (SP) — USP, Bauru, SP, Brazil.

Braulio Pasternak Jr, MSc, PhD, and Dr. Cesar Augusto Pereira Oliveira are from the Department of Endodontics, Brazilian Dentistry Association, Florianópolis, Santa Catarina, Brazil.

24 Endodontic practice

Figure 1: Clinical (A), radiographic (B), and tomographic (C, D) aspects showing the presence of the gutta-percha cone in the palatine root overextended into the maxillary sinus Volume 12 Number 1

CLINICAL of the surgical field, and less vibration and noise.10,13 This case report describes an endodontic surgery to remove an overextended guttapercha master cone from the maxillary sinus using CBCT to aid in diagnosis and surgical planning and the ultrasound to perform the osteotomy.

Case report A 27-year-old woman sought dental care due to sensitivity in the apical region of the maxillary left second premolar (tooth No. 25), but without visually noticeable clinical changes. The periapical radiographic showed severe overextension of a gutta-percha cone through the foramen of the palatal of tooth No. 25. A CBCT confirmed the position of the palatal root and the extruded material within the maxillary sinus (Figure 1), which led to the decision to conduct an endodontic surgery to remove the overextended material.

Local anesthesia was performed by alveolar superior posterior terminal infiltration and using the infraorbital nerve block technique with 4% articaine. A horizontal intrasulcular incision that extended from the distal surface of the maxillary left first molar (tooth No. 26) to the mesial region of maxillary left first premolar (tooth No. 24), and a vertical incision, made on the mesial surface of tooth No. 24, were performed in the buccal vestibule to facilitate the elevation of the full-thickness flap.

After mucoperiosteal divulsion, no evidence of vestibular cortical bone fenestration was perceived. Once the position of the root apex was established with the aid of CBCT, a quadrangular-shaped sinus window was accomplished to give access to the maxillary sinus. The osteotomy was performed by means of the ultrasonic insert Osteo 19 (Helse Dental Technology, Santa Rosa de Viterbo, SP, Brazil) (Figure 2) attached to the ultrasonic device Jet Sonic (Gnatus, RibeirĂŁo Preto, Brazil) used in endo function with the power level set at 10 and under saline coolant spray. The gutta-percha master cone was easily visualized within the sinus, and then the surgeon proceeded to remove it with the aid of curettes (Figure 3). To prevent the overflow of gutta percha into the maxillary sinus, the palatal side of the root was protected with gauze. In the transoperative radiography, complete elimination of guttapercha was observed, and then the apical plasty was performed with an apical file.

The bony lid was folded back, covered with the mucoperiosteal flap, and then the horizontal incision was sutured with 26 Endodontic practice

Figure 2: Ultrasonic surgical insert Osteo19 (Helse Dental Technology) for ultrasound (A, B, C)

Figure 3: Operative maneuvers: (A) Beginning of ostectomy with ultrasound. (B) Surgical window. (C) Maxillary sinus exposure.

(D) Root access

overlapping points, simple transpapillary, and vertical stiches.

The patient was discharged with instructions regarding necessary postoperative care, and a prescription of an anti-inflammatory medication for 5 days. At a 1-week postoperative appointment, the sutures were removed, and the area presented uneventful healing with no evidence of infection and oroantral communication. At the 12-month

follow-up, both clinical and radiographic exams showed an absence of symptoms and an adequate healing (Figure 4).

Discussion Anatomically, the premolars and molars come into a close relationship with the maxillary sinus, and their roots may project into it.14,15 When there is a need for surgical intervention in any of these teeth, CBCT can be a Volume 12 Number 1

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Figure 4: (A) Transoperative radiography, (B) suture, (C) clinical, and (D) radiographic control after 12 months

resource used to obtain a three-dimensional view and the actual relationship of the tooth/ lesion with the maxillary sinus.11,16 In this case, CBCT clearly showed that the gutta-percha cone had overpassed the apex of the palatal root and established the distance that it had penetrated the wall of the maxillary sinus.

The roots of the upper posterior teeth are in direct contact with the maxillary sinus, and the extrusion of endodontic sealers or gutta percha into it can trigger an inflammatory process that persists until the material is removed.17 The presence of a foreign substance within the maxillary antrum 28 Endodontic practice

may lead to the onset of sinusitis,2 pain on mastication, and tenderness palpation.17 Symptoms like sinus tenderness and nasal stuffiness were experienced by a patient because the gutta percha that extruded into the maxillary sinus had migrated to the ethmoid sinus. Furthermore, as most root canal filling materials are zinc oxide-based (including gutta-percha), they can favor the growth of Aspergillus fumigatus, leading to the development of Aspergillosis infection19-21 and a fungus ball formation.22 The attempt to remove extruded gutta percha via the root canal is not always

successful, and it is often necessary to perform surgery.2,10 In cases where endodontic surgery is required, the conventional technique, which uses manual and rotary instruments, is the most used in osteotomy and apicectomy. However, the use of ultrasound in oral surgeries in general has gained prominence and has shown some advantages over conventional surgery.10,13 In endodontic surgery, ultrasound has been used for osteotomy procedures, root-end resection, preparation of the apical cavity for retrofilling, and enucleation of radicular cysts, in addition to other types of procedures.10 Ultrasound has Volume 12 Number 1

performed with ultrasound is an alternative technique that provides the patient with a safer and comfortable surgery.

11. Low KM, Dula K, Burgin W, von Arx T. Comparison of periapical radiography and limited cone-beam tomography in posterior maxillary teeth referred for apical surgery. J Endod.

2008;34(5):557-562.

12. Rashad A, Kaiser A, Prochnow N, et al. Heat production during different ultrasonic and conventional osteotomy preparations for dental implants. Clin Oral Implants Res. 2011;22(120:1361-1365.

Conclusions It was concluded that the use of CBCT was important in the diagnosis and surgical planning of this case and that the use of the ultrasound for the osteotomy proved to be a simpler and safer alternative to avoid injuries to vital structures. EP

13. Pavlíková G, Foltán R, Horká M, et al. Piezosurgery in oral and maxillofacial surgery. Int J Oral Maxillofac Surg.

2011;40(5):451-457.

14. Hauman CH, Chandler NP, Tong DC. Endodontic implications of the maxillary sinus: a review. Int Endod J. 2002;35(2):127-141.

15. von Arx T, Fodich I, Bornstein MM. Proximity of premolar roots to maxillary sinus: a radiographic survey using cone-beam computed tomography. J Endod. 2014;40(10):1541-1548.

16. Lavasani SA, Tyler C, Roach SH, et al. Cone-beam computed tomography: anatomic analysis of maxillary posterior teeth-impact on endodontic microsurgery. J Endod. 2016;42(6):890-895.

REFERENCES 1. Da Silva D, Endal U, Reynaud A, et al. A comparative study of lateral condensation, heat-softened gutta-percha, and a modified master cone heat-softened backfilling technique.

Int Endod J. 2002;35(12):1005-1011.

17. Brooks JK, Kleinman JW. Retrieval of extensive guttapercha extruded into the maxillary sinus: use of 3-dimensional cone-beam computed tomography. J Endod.

2013;39(9):1189-1193.

2. Oguz Y, Soydan SS. Maxillary sinusitis as a complication of an extruded gutta-percha: a case report. Cumhuriyet Dent J. 2014;17(suppl 1) :36-39.

3. Kaplowitz GJ. Penetration of the maxillary sinus by overextended gutta percha cones. Report of two cases. Clin Prev Dent. 1985;7(2):28-30.

18. Ishikawa M, Mizuno T, Yamazaki Y, et al. Migration of guttapercha point from a root canal into the ethmoid sinus. Br J Oral Maxillofac Surg. 2004;42(1):58-60.

4. Ritchie GM, Anderson DM, Sakumura JS. Apical extrusion of thermoplasticized gutta-percha used as a root canal filling.

J Endod. 1988;14(3):128-132.

19. Khongkhunthian P, Reichart PA. Aspergillosis of the maxillary sinus as a complication of overfilling root canal material into the sinus: report of two cases. J Endod. 2001;27(7):476-478.

5. Scarparo RK, Grecca FS, Fachin EV. Analysis of tissue reactions to methacrylate resin-based, epoxy resin-based, and zinc oxide-eugenol endodontic sealers. J Endod.

2009;35(2):229-232.

20. Giardino L, Pontieri F, Savoldi E, Tallarigo F. Aspergillus mycetoma of the maxillary sinus secondary to overfilling of a root canal. J Endod. 2006;32(7):692-694.

6. Ribeiro DA. Do endodontic compounds induce genetic damage? A comprehensive review. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2008;105(2):251-256.

21. Yamaguchi K, Matsunaga T, Hayashi Y. Gross extrusion of endodontic obturation materials into the maxillary sinus: a case report. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2007;104(1):131-134.

7. Costa F, Robiony M, Toro C, Sembronio S, Politi M. Endoscopically assisted procedure for removal of a foreign body from the maxillary sinus and contemporary endodontic surgical treatment of the tooth. Head Face Med. 2006;2:37.

22. Mensi M, Piccioni M, Marsili F, et al. Risk of maxillary fungus ball in patients with endodontic treatment on maxillary teeth: a case-control study. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2007;103(3):433-436.

8. Pasqualini D, Scotti N, Ambrogio P, Alovisi M, Berutti E. Atypical facial pain related to apical fenestration and overfilling. Int Endod J. 2012;45(7):670-677.

23. García B, Peñarrocha M, Peñarrocha MA, von Arx T. Apical surgery of a maxillary molar creating a maxillary sinus window using ultrasonics: a clinical case. Int Endod J. 2010;43(11):1054-1061.

9. Cotton TP, Geisler TM, Holden DT, Schwartz SA, Schindler WG. Endodontic applications of cone-beam volumetric tomography. J Endod. 2007;33(9):1121-1132.

24. Troedhan A, Kurrek A, Wainwright M. Ultrasonic piezotome surgery: is it a benefit for our patients and does it extend surgery time? A retrospective comparative study on the removal of 100 impacted mandibular 3rd molars. Open J Stomatol. 2011;1(4):179-184.

10. Abella F, de Ribot J, Doria G, Duran-Sindreu F, Roig M. Applications of piezoelectric surgery in endodontic surgery: a literature review. J Endod. 2014;40(3):325-332.

Endodontic Practice US clinical

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CLINICAL

been shown to be efficient, more comfortable for both the patient and professional, and has decreased the risk of accidents and contamination. Also, ultrasound produces a more visible surgical field due to less bleeding and allows for greater safety, especially when surgery is close to important areas such as nerves, blood vessels, and the maxillary sinus.10,13,23 In this case report, the osteotomy was performed with conventional nonsurgical ultrasound and a new insert developed by the company Helse Dental Technology, which proved to be very effective in the procedure.

This technique allowed a safer osteotomy without risk of sinus membrane perforation, as can happen with the use of chisels and drills, better access to the area, and a more conservative removal of bone. Through the surgical window, it was possible to access the root and remove the extravasated material with a good safety margin and reduced bone loss.

The communication between the surgical cavity and the maxillary sinus is another critical factor to be taken into consideration because contamination can lead to failure of surgery. At the end of the procedure, the juxtaposition of the suture was obtained with simple transpapillary stitches. Perfect readaptation of the flap was achieved, thereby avoiding any accidental breakpoints and exposure of the surgical field. The postoperative period was quite comfortable for the patient, confirming previous findings.23,24 Thus, it can be concluded that the osteotomy

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CLINICAL RESEARCH

The effectiveness of different rotary systems in the removal of gutta-percha and sealer obturation in ovoid canals Drs. Aline Yumi Mukai, Ana Grasiela da Silva Limoeiro, Alexandre Sigrist De Martin, Augusto Shoji Kato, Carlos Eduardo da Silveira Bueno, Daniel Guimarães Pedro Rocha, Rina Andrea Pelegrine, and Carlos Eduardo Fontana discuss different systems for the removal of the obturation material Abstract Introduction During nonsurgical endodontic retreatment, the complete removal of the previous filling material is necessary to facilitate proper cleaning, disinfection, and reintervention of the root canal system. This study aimed to evaluate the effectiveness of ProTaper Next™ (PN) (Dentsply Maillefer, Ballaigues, Switzerland) and ProDesign Logic (PL) (Easy Equipamentos Odontológicos, Belo Horizonte, Brazil) rotary systems compared to the ProTaper Universal Retreatment (PUR) (Dentsply Maillefer, Ballaigues, Switzerland) system in the removal of gutta percha and sealer in ovoid canals.

Materials and methods Thirty human extracted mandibular incisors were instrumented with the ProTaper Aline Yumi Mukai, DDS, MsC, is from the Department of Endodontics, São Leopoldo Mandic Dental Research Center, Campinas, São Paulo, Brazil.

Ana Grasiela da Silva Limoeiro, DDS, MsC, is from the Department of Endodontics, Faculdade de Ilhéus, Ilhéus, Bahia, Brazil.

Alexandre Sigrist De Martin, DDS, MsC, PhD, is from the Department of Endodontics, São Leopoldo Mandic Dental Research Center, Campinas, São Paulo, Brazil.

Augusto Shoji Kato DDS, MsC, PhD, is from the Department of Endodontics, São Leopoldo Mandic Dental Research Center, Campinas, São Paulo, Brazil.

Universal system up to the F3(30.09) file and filled with gutta percha and AH Plus® (Dentsply Maillefer) sealer by the Tagger12 hybrid technique. The canals were randomly divided into three groups according to the technique used for removing the root filling material (n = 10): • PUR group - D1(30.09), D2(25.08) and D3(20.07) • PN group - X2(25.06) and X3(30.07) • PL group - 30.05 The time required to remove the root filling material was recorded. The roots were sectioned longitudinally and photographed.

Results The area of the remaining obturation material was delineated using Image Tool 3.0 software (Image Tool; University of Texas Health Science Center, San Antonio, CA, EUA) and thus, the percentage of remaining material was obtained across the canal and in each third separately. Data was analyzed statistically using the Kruskal-Wallis and Student-Newman-Keuls tests (p <0.05). The results showed that there was no significant difference between the three groups concerning the time of retreatment and the amount of root obturation material remaining considering the entire canal and in each third

Carlos Eduardo da Silveira Bueno, DDS, MsC, PhD, is from the Department of Endodontics, São Leopoldo Mandic Dental Research Center, Campinas, São Paulo, Brazil.

Daniel Guimarães Pedro Rocha, DDS, MsC, PhD, is from the Department of Endodontics, São Leopoldo Mandic Dental Research Center, Campinas, São Paulo, Brazil.

Rina Andrea Pelegrine, DDS, MsC, PhD, is from the Department of Endodontics, São Leopoldo Mandic Dental Research Center, Campinas, São Paulo, Brazil.

Carlos Eduardo Fontana, DDS, MsC, PhD, Department of Endodontics, School of Dentistry, Pontificia Universidade Católica de Campinas, Campinas, SP, Brazil.

Figure 1: ProTaper retreatment cross section (www.dentsply.com) 30 Endodontic practice

separately. The cervical third presented the smallest amount of remnant in the three groups (p <0.05).

Conclusion It was concluded that no technique completely removed all the obturation material from the walls of the root canals. The ProTaper Next and ProDesign Logic systems were as effective as the ProTaper Universal Retreatment system in the removal of the obturation material.

Introduction Nonsurgical retreatment is the first option to correct a possible failure of the endodontic treatment, eliminating or reducing the microbial load of the root canal,1 but studies show that no technique used for this purpose can release the walls of the root canals2,3 completely. Several methods have been used to remove obturation material from the interior of the root canal, including manual stainless steel files, drills, heated instruments, ultrasonic, and rotary files4 with or without solvents.5 Currently, rotary and reciprocating instrumentation techniques with nickeltitanium (NiTi) instruments are indicated as alternatives to manual instrumentation for the removal of obturation material from root canals,6 besides being safe, fast, and efficient in the removal of gutta percha.7 The ProTaper Universal Retreatment (PUR) system was developed specifically for the removal of obturation material during endodontic retreatment. It consists of three instruments: D1 (30.09), D2 (25.08), and D3 (20.07), which were designed to be used in the cervical, middle, and apical thirds of the root canal, respectively. These instruments have a triangular convex section (Figure 1), and only D1 has an active tip to facilitate initial penetration into the filling material.8,9 Volume 12 Number 1

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Advanced Bioceramics

MKT19013-Rev 0

CLINICAL RESEARCH ProTaper Next is a rotary system made of a NiTi M-wire alloy, which gives greater flexibility and resistance to cyclic fatigue to the instrument. The system includes five shaping instruments: X1 (17.04), X2 (25.06), X3 (30.07), X4 (40.06), and X5 (50.06). All five are characterized by an innovative offcentered rectangular cross section (Figure 2), which has been claimed to give the files a “swaggering” movement as it advances into the root canal.10 ProDesign Logic system (Figure 3), a NiTi alloy with CM heat treatment, increases flexibility and fatigue resistance, has an inactive rounded tip, and variable cutting angle at over the length of the active part, decreasing the screw-in effect. The shaping files are 25.05, 30.05, 35.05, and 40.05.

This study aimed to evaluate, in vitro, the percentage of remaining filling material in mandibular extracted human incisors after removal obturation material with ProTaper Universal Retreatment, ProTaper Next, or ProDesign Logic systems. The null hypothesis is that there is no significant difference in the ability to remove the root canal obturation between the three systems.

Materials and Methods Teeth selection The local ethics committee approved this study (NP 1,079,711). Thirty recently

Figure 2: ProTaper Next cross section (www.dentsply.com)

Figure 3: ProDesign Logic cross section (www.easy.odo.br) 32 Endodontic practice

extracted human mandibular incisors with complete rhizogenesis, single ovoid canal, the absence of cracks, endodontic treatment, and calcification were selected and stored in 0.1% thymol solution until use.

The canal was considered ovoid when the buccal-lingual diameter was twice greater or greater than the mesiodistal diameter in the first two-thirds of the canal measured in the CDR radiographic sensor software.11 The crown was removed by a doublesided diamond disc, standardizing the length of the teeth in 15 mm, confirmed by a digital pachymeter (TESA® DIGIT-CAL® Switzerland). After this procedure, a stainless steel file type K No. 10 (Dentsply Maillefer) was inserted into the root canals until the tip of the instrument was only visible in the apical foramen with the aid of the dental operating microscope (OPMI® Pico; Carl Zeiss Meditec AG, Jena, Germany) under 12.5x magnification. The working length (WL) was determined by subtracting 1 mm from this measurement.

Root canal treatment The canals were instrumented by a single operator using the NiTi ProTaper Universal rotary files driven to the X-Smart® Plus electric motor (Dentsply Maillefer) at a speed of 300 rpm and 3N. The sequence was performed according to the instructions provided by the manufacturer, using instruments F1, F2, and F3 until the working length was reached. Foraminal patency was maintained with a No. 10 K-file. The root canals were irrigated with 2.5% sodium hypochlorite solution (NaOCl) preceding the use of each instrument during canal shaping, totaling 25 mL of solution per tooth. At the end of the irrigation, the smear layer was removed with 5 mL 17% EDTA for 1 minute, followed by a final flush with 5 mL of 2.5% solution of NaOCl. The canals were dried with ProTaper F3 absorbent paper points (Dentsply Maillefer) and filled with a ProTaper F3 gutta-percha cone (Dentsply Maillefer) and AH Plus sealer (Dentsply Maillefer) using the Tagger hybrid technique,12 which consists of the lateral obturation technique complemented by the use of the McSpadden gutta condenser. Coronal access was sealed with Coltosol® (Coltene Whaledent, Cuyahoga Falls, Ohio). Buccolingual- and mesiodistal-oriented radiographs were taken with a digital sensor (CDR Schick

by Sirona, Dentsply Sirona, Long Island City, New York) to verify the quality of the root canal obturation. Samples were stored in

an environment with 100% humidity at 37ºC for 30 days to allow full setting of the sealing. The samples were randomly divided into three groups (n =1 0) using a computerized algorithm (http //www.random.org), according to the techniques of gutta-percha removal.

Removal of filling material PUR group: The removal of the root canal filling material was performed with a constant speed of 500 rpm for D1 (30.09) and 400 rpm for both D2 (25.08) and D3 (20.07) with a torque of 3Ncm. These instruments were sequentially used in the cervical, middle, and apical thirds, respectively, until reaching WL with the instrument D3. The files were driven on the X-Smart Plus (Dentsply Maillefer) electric motor according to the manufacturer’s instructions.

PN group: In the PN group, X3 file (30.07) was used in the cervical and middle thirds and X2 file (25.06) in the apical third.

The instruments were driven in the X-Smart Plus electric motor, in continuous rotation at the speed of 500 rpm and a torque of 3 Ncm. The preparation was performed by root thirds until the instrument reached the WL. PL group: The ProDesign Logic instrument 30.05 was used in continuous rotation at a speed of 950 rpm and a torque of 4 Ncm. The instruments were applied in all of the groups using an “in-and-out” motion, and a slight apical pressure was carried out until the instrument reaches the WL followed by a “brushing motion” against the lateral walls during removal file.

Irrigation during filling material removal was performed with 2.5% NaOCl using a total of 25 mL of solution per tooth. Final irrigation was performed with 5 mL 17% EDTA for 1 minute, followed by 5 mL 2.5% NaOCl for each specimen. After the final irrigation, the canals were dried with absorbent points.

Obturation removal was considered complete when there was no obturation material adhered to the instrument used or on the walls of the canal, which were checked with an operating microscope under 12.5x magnification. The instruments were used in three canals and then discarded.13 A single operator with extensive experience in the systems performed the instrumentation of all specimens. No instrument fractures occurred during obturation material removal.

Evaluation of filling material removal Retreatment time was recorded in minutes for each tooth. The timer was Volume 12 Number 1

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CLINICAL RESEARCH triggered only when the instrument was moving within the canal. The time for irrigation and instrument change was not included.

A groove was made on the buccal and lingual surfaces with a double-sided diamond disc (Brasseler USA®) for specimen orientation, and the teeth were cleaved with the aid of a Lecron spatula (Quinelato Company Rio Claro, São Paulo, Brazil).

Both halves were photographed using a Sony DSC T20 digital camera (Sony Corporation, Tokyo, Japan) coupled to an operating microscope under 5x magnification.

Images were transferred to specific imaging software Image Tool for Windows v.3.00, which was used to design and calculate the areas of the root canal and the remaining filling material, expressed in square pixels.

Mean percentage values were then calculated and compared.

The analysis was performed in the cervical, middle, and apical thirds separately, as well as throughout the root canal. Through these measurements, a three simple rule was performed, in which the area of the canal was 100%, and the remaining filling material area equal to x (Figure 4). As shown below:

Remaining area of root filling material X 100 / Canal area = % Remaining area of root filling material Statistical analysis The Biostat 4.0 Program performed D’Agostino’s normality test, and the sample presented non-normal behavior. Thus, the Kruskal-Wallis test, supplemented by Student-Newman-Keuls, was used at a significance level of 5% (p <0.05).

Results The time required for the procedure was 7.17 min for the PUR group, 8.51 min for the PN group, and 5.56 min for the PL group.

No statistical significant difference (p> 0.05) was observed among the groups.

The mean obturation material residue was 6.17% in the PUR group, 10.86% in the PN group, and 8.76% in the PL group. No statistical significant difference (p> 0.05) was observed among the groups in the amount of the remaining obturation material, considering the total area of the canal (Table 1).

The descriptive analysis regarding the differences between the three techniques in the cervical, middle, and apical thirds of the roots is presented in Table 2. There was no significant difference between the same thirds of different groups (p> 0.05).

In comparisons by thirds within the same sample group, smaller areas of remaining root canal obturation material were found in the cervical third of all groups with significant differences concerning the middle and apical thirds (p <0.05).

Discussion

Figure 4: Design of the area of the remaining obturation material in canal thirds

Table 1: The remaining root canal material throughout the study (expressed as a percentage of the area) for each group

MD (ID) MA (SD)

PUR (ProTaper Universal Retreatment)

PN PL P-KW (ProTaper Next) (ProDesign Logic)

3.69 (6.57) 6.17 (5.25)A

10.57(12.03) 10.86 (7.30)A

8.48 (4.65) 8.76 (3.87)A

0.2276

Median (MD), arithmetic mean (AM), interquartile deviations (ID), standard deviations (SD) and Student-Newman-Keuls (KW) statistical test. Equal capital letters indicate no significant difference: p> 0.05.

34 Endodontic practice

Due to the advancement of techniques and instruments in endodontics, endodontic treatment has become more predictable and with a high success rate, but failures may still occur.14 The nonsurgical approach has been the preferred treatment to correct such failures because it is the most conservative method and still provides a more favorable long-term result when compared to endodontic surgery.15,16 In endodontic retreatment, the complete removal of the root obturation material is fundamental to allow the effective disinfection of the root canal. However, it is not always possible to completely remove obturation with the currently available methods and instruments.17 Some studies show that there is no significant difference between rotary and manual techniques18,19; others have shown that the manual technique is more efficient20,21; and others have stated Volume 12 Number 1

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CLINICAL RESEARCH Table 2: The remaining filling material in each third of the canal for each group

CT

MT

AT P-KW

PUR

PN

PL

P-KW

MD (DI)

0.00 (0.17)

0.00 (0.42

0.89 (1.32)

0.4470

AM (SD)

0.28(0.53)Aa

1.22 (2.63)Aa

1.53 (2.27)Aa

MD (ID)

4.25 (6.82)

9.10 (21.05)

13.68 (6.62)

AM (SD)

5.90 (6.45)Ba

15.32 (13.43)Ba

11.71 (5.31)Ba

MD (ID)

16.93 (23.41)

30.49 (20.96)

20.41 (13.82)

AM (SD)

23.26(18.05)Ca

26.65 (15.33)Ba

21.82(11.74)Ba

0.0001

0.003

0.0001

)

0.0715

0.8041

Median (MD), arithmetic mean (AM), interquartile deviations (ID), standard deviations (SD) and Kruskal-Wallis statistical test complemented by Student-Newman-Keuls (KW). CT: cervical third; MT: middle third; AT apical third; different capital letters in the vertical direction: p <0.05; lowercase letters in the horizontal direction: p> 0.05.

that the rotary technique has better performance.22,23 This discrepancy in the results can be attributed to differences in obturation technique, retreatment methods, tooth groups, evaluation methodology, taper, and tip of the instruments.23 Several methods have been used to evaluate root canal cleansing after retreatment, including radiographic evaluation,24 diaphanization,25 longitudinal root cutting with quantitative evaluation of the remnant obturation material,26 qualitative evaluation using a scoring system,27 and micro-CT.28 Although the methodology used in this study is well established in the literature, it has limitations because it provides only twodimensional pieces of information about a three-dimensional structure,29 and also, the gutta percha can be displaced or lost during the cleavage process.30 Due to these deficiencies, micro-CT has been used because it is a high-resolution, non-destructive method that allows three-dimensional measurement of the volume of the obturation material,29 but the cleavage process remains a viable method.30 In this study, PN and PL rotary systems, which were initially designed for canal instrumentation, were compared by the obturation material remove capacity to the PUR system, which was developed specifically for this purpose. The cervical third presented significantly less remaining obturation material compared to the other thirds of the three groups evaluated.31 In the PUR group, the remaining amount among the thirds was statistically different. In the PN and PL groups, the cervical third had significantly less remaining filling material than the middle 36 Endodontic practice

and apical thirds, with no statistical difference between them. This result may suggest that the taper of PUR instrument D2 - 25.08 is more adequate compared to PN and PL instruments in the middle third of lower incisors, so that the instrument contacts the walls of the canal more efficiently in this third.

Although the PUR group has the disadvantage that the tip of its last file D3(20.07) is smaller, compared to the other groups that present tip 30(PL) or 25(PN), the favorable result in the removal of the gutta percha is according to the study of Takahashi, et al.2 It can be attributed to the fact that the design of these instruments allows cutting not only the gutta percha, but also a superficial layer of dentin during the retreatment.3 PN and PL systems were as effective in the removal of obturation material as the PUR system. The PN file has a rectangular cross section, and the center of mass and the center of rotation are offset. The device generates a mechanical wave making its movement asymmetrical, which promotes larger areas of contact in the walls of the root canals and, consequently, greater removal of obturation material.32 By the design and high speed with which it is driven, the PL is also capable of removing a large quantity of obturation material. These characteristics may have contributed to the excellent performance of these systems, although they have not been developed for the retreatment procedures.

The results of this study are in part according to the study of Özyürek, et al.,31 who stated that the PN and PUR systems had a similar performance in the removing of the gutta percha. However, concerning the

time required for the procedure, the PUR system was faster, differing from our study in which there was no difference between the three groups, as well as the study by Nevares, et al.,32 in which Reciproc and PN did not show differences in the preparation time.

In this study, the three systems evaluated have different alloys — NiTi, M-Wire, and CM-Wire — and did not have significant differences in the removal of filling material, demonstrating that although CM-Wire files (PL group) are more flexible than NiTi files (PUR) and M-Wire files (PN), it had the same ability to remove root canal filling material. It may be suggested that the flexibility of the CM-Wire file assists in the “brushing motion” against the canal walls during the retreatment procedures. This result is in agreement with the study of Rodrigues, et al.,33 where the authors compared the ProDesign R and ProDesign Logic 40.05 (CM-Wire) with Reciproc R 25 (M-Wire) and MTwo 40.04 (NiTi) and had no significant difference in the amount of remaining obturation material.

Conclusion Based on the results obtained in this in vitro study, it can be concluded that all the evaluated rotary systems were equivalent in removing obturation material from oval canals, but the remaining gutta percha and sealer were observed on the walls of all the canals, regardless of the technique. EP

REFERENCES 1. Torabinejad, M, Corr, R, Handysides R, Shababang S. Outcomes of nonsurgical retreatment and endodontic surgery: a systematic review. J Endod. 2009;35(7):930-937.

2. Takahashi CM, Cunha RS, de Martin AS, et al. In vitro evaluation of the effectiveness of the rotary ProTaper universal retreatment system for gutta-percha removal with or without a solvent. J Endod. 2009;35(11):1580-1583.

3. Rios MA, Villela AM, Cunha RS, et al. Efficacy of 2 reciprocating systems compared with a rotary retreatment system for gutta-percha removal. J Endod. 2014;40(4):543-546.

4. Mello Junior JE, Cunha RS, Bueno CES, Zuolo ML. Retreatment efficacy of gutta-percha removal using the microscope clinical and ultrasonic instruments: part I — an ex vivo study. Oral Surg Oral Med Oral Pathol Oral Radiol Endod.

2009;108(1):59-62.

5. Bueno CES, Delboni MG, Araujo RA, Carrara HJ, Cunha RS. Effectiveness of rotary and hand files in gutta-percha and sealer removal using chloroform or chlorhexidine gel.

Braz Dent J. 2006;179(2):139-43.

6. de Carvalho Maciel AC, Zaccaro Scelza MF. Efficacy of automated versus hand instrumentation during root canal retreatment: an ex vivo study. Int Endod J. 2006;39(10):779-784.

7. Baratto Filho F, Ferreira EL, Fariniuk LF. Efficiency of the 0.04 taper ProFile during the re-treatment of gutta-percha-filled root canals. Int Endod J. 2002;35(8):651-654.

8. Marfisi K, Mercade M, Plotino G, et al. Efficacy of three different rotary files to remove gutta-percha and Resilon from root canals. Int Endod J. 2010;43(11)1022-1028.

9. Hussne RP, Braga LC, Berbert FL, Buono VT, Bahia MG. Flexibility and torsional resistance of three nickeltitanium retreatment instrument systems. Int Endod J. 2011;44(8):731-738.

10. da Silva Limoeiro AG, Dos Santos AH, De Martin AS, et al.

Micro-computed tomographic evaluation of 2 nickel-titanium instrument systems in shaping root canals. J Endod.

2016;42(3):496-499.

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12. Tagger M, Tamse A, Katz A, Korzen BH. Evaluation of the apical seal produced by a hybrid root canal filling method, combining lateral condensation and thermatic compaction.

J Endod. 1984;10(7):299-303.

13. Rödig T, Kupis J Konietschke F, et al. Comparison of hand and rotary instrumentation for removing gutta-percha from previously treated curved root canals: a microcomputed tomography study. Int Endod J. 2014;47(2):173-182.

14. Siqueira JF Jr. Aetiology of root canal treatment failure: why well-treated teeth can fail. Int Endod J. 2001;34(1):1-10.

15. Hammad M, Qualtrough A, Silikas N. Three-dimensional evaluation of the effectiveness of hand and rotary instrumentation for retreatment of canals filled with different materials.

J Endod. 2008;34(11):1370-1373.

16. Só MVR, Saran C, Magro ML Vier-Pelisser FV, Munhoz M. Efficacy of ProTaper retreatment system in root canals filled with gutta-percha and two endodontic sealers. J Endod.

2008;34(10):1223-1225.

17. Ersev H, Yilmaz B O, Dinçol ME Daglaroglu R. The efficacy of retreatment ProTaper Universal rotary single instrumentation to remove gutta-percha cones cemented with several endodontic sealers. Int Endod J. 2012;5(8):756-762.

CLINICAL RESEARCH

11. Martins MP, Duarte MAH, Cavenago BC, Kato AS, Bueno CES. Effectiveness of the ProTaper Next and Reciproc systems in removing root canal filling material with sonic or ultrasonic irrigation: a micro-computed tomographic study.

J Endod. 2017;43(3):467-471.

18. Barrieshi-Nusair KM. Gutta-percha retreatment: effectiveness of nickel-titanium rotary instruments versus stainless steel hand files. J Endod. 2002;28(6):454-456.

19. Kfir A, Tsesis I, Yakirevich E, Matalon S, Abramovitz I. The efficacy of five techniques for removing root material: microscopic versus radiographic evaluation. Int Endod J. 2012;45(1):35-41.

20. Zmener O, Pameijer CH, Banegas G. Retreatment efficacy of hand versus automated instrumentation in oval-shaped root canals: an ex vivo study. Int Endod J. 2006;39(7):521-526.

21. Xu L, Zhang L, Zhou X, et al. Residual filling material in dentinal tubules after gutta-percha removal observed with scanning electron microscopy. J Endod. 2012; 38(3):293-296.

22. Bernardes RA, Duarte MAH, Vivan RR, et al. Comparison of three retreatment techniques with ultrasonic activation in flattened canals using micro-computed tomography and scanning electron microscopy. Int Endod J. 2016;49(9):890-897.

23. Saad AY, Al-Hadlaq SM, Al-Katheeri NH. Efficacy of two rotary NiTi instruments in the removal of gutta-percha during root canal retreatment. J Endod. 2007;33(1):38-41.

24. Masiero AV, Barletta FB. Effectiveness of different techniques for removing gutta-percha during retreatment. Int Endod J. 2005;38(1):2-7.

25. Schirrmeister JF, Wrbas KT, Meyer KM, Altenburger MJ, Hellwig E. Efficacy of different rotary instruments for gutta-percha removal in root canal retreatment. J Endod.

2006;32(5):469-472.

26. Imura N, Kato AS, Hata GI, et al. A comparison of the relative efficacies of four hand and rotary instrumentation techniques during endodontic retreatment. Int Endod J. 2000;33(4):361-366.

27. Hülsmann M, Bluhm V. Efficacy, safety and cleaning ability of different rotary NiTi instruments in root canal retreatment.

Int Endod J. 2004;37(7):468-476.

28. Fruchi LC, Ordinola-Zapata R, Cavenago BC, et al. Efficacy of reciprocating filling instrument for removing the material in curved canals obturated with a single-cone technique: micro-computed tomographic analysis. J Endod.

2014;40(7):1000-1004.

29. Zuolo AS, Zuolo ML, da Silveira Bueno CE, Chu R, Cunha RS. Evaluation of the efficacy of TRUShape and Reciproc file systems in the removal of root filling material: an ex vivo micro-computed tomographic study. J Endod.

2016;42(2):315-319.

30. Gu LS, Ling JQ, Wei X, Huang XY. Efficacy of ProTaper Universal rotary retreatment system for gutta-percha removal from root canals. Int Endod J. 2008;41(4):288-295.

31. Özyürek T, Demiryürek EÖ. Efficacy of different nickeltitanium instruments in gutta-percha removal during root canal retreatment. J Endod. 2016;42(4):646-649.

32. Nevares G, de Albuquerque DS, LG Freire, et al. Efficacy of ProTaper NEXT compared to Reciproc in obturation material from severely curved root canals: a micro-computed tomography study. J Endod. 2016;42(5):803-808.

33. Rodrigues CT, Duarte MA, de Almeida MM, de Andrade FB, Bernardineli N. Efficacy of CM-Wire, M-Wire, and NickelTitanium instruments for removing filling material from curved root canals: a micro-computed tomography study.

J Endod. 2016;42(11):1651-1655.

Volume 12 Number 1

Endodontic practice 37

RESEARCH

A comparative study between the single guttapercha cone technique and GuttaCore in the filling of simulated lateral canals Drs. Juan Antonio Araujo, Carlos Cantarini, Viviana Han, and Fernando Goldberg study different techniques for obturating lateral canals in premolars Abstract Objective To compare the ability of the single gutta-percha cone technique and the GuttaCore® system (Dentsply Sirona, Ballaigues, Switzerland) for the obturation of simulated lateral canals in extracted human premolars.

Materials and methods The root canals of 26 extracted human mandibular premolars were instrumented with WaveOne® primary (Dentsply Sirona) and irrigated with NaOCl 2.5%. Then three simulated lateral canals were drilled in the mesial surface of the roots, one in each third, using an Engine Reamer No. 15. To mimic the pulpal tissue, a colored paraffin gel was injected inside the root canals. To mimic the periodontal tissue, the roots were covered with rubber foam and Teflon™. Afterward, the root canals were instrumented with WaveOne large and irrigated with NaOCl 2.5%. Then, EDTAC and NaOCl were activated with an EndoActivator® (Dentspy Sirona). The teeth were divided in two groups of 13 specimens each.

• Group 1: obturated with a WaveOne large single cone.

• Group 2: obturated with a GuttaCore® large.

In both groups, AH Plus® (Dentsply DeTrey GmbH, Konstanz, Germany) was used as a sealer. Digital X-rays were taken in the buccolingual direction, and the lateral canals were categorized as not filled, partially filled, and totally filled. The specimens were cleared and photographed in order to know the type of material located inside the simulated lateral canals. Data between

Juan Antonio Araujo, DDS, and Fernando Goldberg, DDS, PhD, are from the Department of Endodontics, Faculty of Dentistry University of Buenos, Buenos Aires, Argentina.

Carlos Cantarini, DDS, and Viviana Han, DDS, are from the Department of Endodontics, School of Dentistry USAL/AOA, Buenos Aires, Argentina.

38 Endodontic practice

techniques in each third were statistically analyzed using the Mann-Whitney test. For the comparison between thirds in each technique, the Friedman test was used.

Results In the postoperative digital images, the comparison within the same third of the root canals showed no statistical significant differences between techniques (P >0.05).

The comparison between thirds in the same technique showed that, in group 1, statistically significant differences between the cervical and the other thirds (P <0.05); but in group 2, not statistically significant differences were detected between thirds (P >0.05). The cleared specimens showed the presence of sealer in all the simulated lateral canals totally obturated from group 1, while in group 2, the cervical third showed 5 with sealer and 5 with gutta-percha, in the middle third 5 and 8, and in the apical third 7 and 5, respectively.

Conclusion With both techniques, the simulated lateral canals were frequently filled, noticing with GuttaCore a tendency to obturate the lateral canals with gutta percha.

Objective The objective of this study was to compare the ability of the single gutta-percha cone technique and the GuttaCore system for the obturation of simulated lateral canals in extracted human premolars.

Introduction The cleaning, shaping, and adequate obturation of the root canal system represents a fundamental objective to achieving success in endodontic therapy. The intricate anatomy of the canals, represented by isthmus, irregularities, and lateral and accessory canals becomes a challenge at every endodontic procedure.

Lateral and accessory canals play an important role because they connect the

main root canal with the periodontal ligament. Pulp necrosis and simultaneous bacterial invasion found in lateral canals of great diameters become a pathway to invade the periodontal ligament and generate a lateral lesion.1 De Deus2 cites the presence of lateral canals in 27.4% of 1,140 analyzed teeth.

Among those, 17% were detected in the apical third, 8.8% in the middle third, and 1.6% in the coronal third of the root.

In canals with necrotic pulp, the organic debris and bacteria along with their byproducts are difficult to remove from the lateral and accessory canals through instrumentation and irrigation.3 In this respect, the obturation of the lateral canals during an endodontic treatment seals the passage of microorganisms toward the periodontal ligament allowing for a favorable environment for tissue repair.4-6 Different procedures were used to evaluate the behavior of the obturation techniques with respect to the lateral and accessory canals. In this study, the use of human teeth with simulated lateral canals, drilled in the three thirds of the root, allows a more accurate study than using plastic or acrylic models.7 Moreover, these models generally have lateral canals with a greater diameter that do not represent a truthful reality.8 The obturation with a single gutta-percha cone and sealer is one of the techniques universally utilized by general dentists, while the thermoplasticized gutta-percha techniques are generally used by endodontists.

Within the thermoplasticized techniques, the GuttaCore® system (Dentsply Sirona, Ballaigues, Switzerland) presents the same principles as its predecessor Thermafil® (Dentsply Maillefer, Ballaigues, Switzerland) with a few modifications. Its core-carrier, easy to remove (partial or total), is made from a cross-linked thermoset elastomer of gutta percha.9 The gutta percha that covers the core is high in viscosity, flowability, and adhesion, and its melting temperature is 56°C.9 GuttaCore is manufactured according to the calibers and tapers of the WaveOne system.

Volume 12 Number 1

Twenty-six human inferior premolars with one root canal and a mature apex were used in this study. All teeth were submerged in a hypochlorite solution at 5.25% for 24 hours and then washed with tap water for 15 minutes. Radiographs in buccolingual and mesiodistal directions were taken to evaluate the root canal anatomy. Conventional access preparations were prepared, and the canal length was visually established by placing a No. 15 file in each root canal until it was seen emerging through the apical foramen. The working length was determined by subtracting 1 mm from the total canal length. The root canals were instrumented with WaveOne primary files up to the working length. For this procedure, a motor XSmart™ Plus was utilized following the manufacturer’s instructions. During the instrumentation, the root canals were irrigated with 2 ml of 2.5% sodium hypochlorite solution using a 25 Gx1" needle (Terumo, Leuven, Belgium).

Afterward, three simulated lateral canals were drilled on the mesial surface of the root (one on each third) by using an Engine Reamer No. 15. To verify canal patency, a K-File No. 10 was introduced in the simulated lateral canals and a K-File No. 25 in the root canal that should be blocked by the previous instrument. Consequently, to simulate the pulp, a paraffin gel (Creativa, Décimo Arte SRL, Buenos Aires, Argentina) colored with a bright green paint (Alba Artistica SA, Buenos Aires, Argentina) was injected inside

the root canal (Figure 1). The extrusion of the colored gel through the apical foramen and simulated lateral canals was visually checked to confirm their complete filling. Then the external surfaces of the root were cleaned with gauze. The roots were covered with a thin film of foam rubber and Teflon tape to mimic the periodontal ligament. Subsequently, the root canals were instrumented again with WaveOne large files up to the working length using a XSmart Plus motor following the manufacturer’s instructions. At the completion of instrumentation, 2 ml of 2.5% sodium hypochlorite solution was used for irrigation. To control the penetration of the solution, a silicone stop was placed on the needle so that it was always inserted 3 mm from the working length. Once the instrumentation was finished, EDTA (Farmadental, Buenos Aires, Argentina) was activated for 1 minute with an EndoActivator and a large activator tip (Dentsply Sirona) at 10.000 cpm and then 2.5% sodium hypochlorite solution activated during 30 seconds with the same device. The root canals were dried with large WaveOne paper points (Dentsply Sirona), and the 26 teeth were randomly separated into two equal groups of 13 (Figure 2).

• Group I (N = 13): The root canals were obturated with a large WaveOne single gutta-percha cones (Dentsply Sirona).

• Group 2(N = 13): The root canals were filled with large GuttaCore (Dentsply Sirona) softened by a ThermaPrep 2 Oven® (Dentsply Sirona, Ballaigues, Switzerland).

In both groups, AH Plus (Dentsply DeTrey GmbH, Konstanz, Germany) was used as a root canal sealer. The sealer was mixed

Figure 1: (left) Mesial view of one specimen showing the orifices of the lateral canals with the bright green paraffin gel that simulates the pulp tissue. (right) Cleared specimen showing the colored paraffin gel inside the main canal and lateral canals

Figure 2: Specimens of both groups with the roots covered with a thin film of foam rubber and Teflon tape to mimic the periodontal ligament

Materials and methods

Volume 12 Number 1

according to manufacturer’s instructions and then applied by coating the canal walls using a No. 25 file.

Postoperative digital images were taken in buccolingual direction and projected in order to evaluate the number of obturated lateral canals, which were categorized as follows: not obturated, partially obturated, and totally obturated.

Samples were then decalcified in 5% nitric acid, dehydrated in ascending concentrations of alcohol (80%, 90%, and 100%), and cleared using methyl salicylate.10 To compare both techniques within each third of the roots, the Mann-Whitney test was used. For the comparison between the thirds of the roots of each technique, the Friedman test was utilized.

Results The results can be observed on Table 1.

In the postoperative digital images, the comparison within the same third of the root canals showed no statistical significant differences between techniques (P >0.05).

The comparison between thirds in the same technique showed that, in group 1, statistical significant differences between the cervical and the other thirds (P <0.05); but in group 2, not statistically significant differences were detected between thirds (P >0.05).

In group 1, the evaluation of the cleared specimens demonstrated that, in the 28 simulated lateral canals completely obturated, the presence of sealer inside them.

In group 2, of the 35 filled lateral canals, 5 were obturated with sealer in the cervical third and 5 with gutta-percha, 5 and 8 in the middle third, and 7 and 5 in the apical third, respectively (Figures 3 and 4).

Endodontic practice 39

RESEARCH

The purpose of this study was to evaluate the capacity of the single cone and GuttaCore techniques for the obturation of the simulated lateral canals.

RESEARCH Discussion The presence of lateral canals in teeth with necrotic pulp may cause lateral periodontal lesions. The instrumentation and irrigation of the root canal along with an adequate tridimensional obturation generally leads to the repair of the pathology with new bone formation.

While some studies demonstrate that the use of mechanized systems of instrumentation allows clinicians to obtain an adequate preparation for the adjustment of the single cone, other publications point out the lack of correlation between instruments and cones within the same system and between instrumented canals and gutta-percha cones, respectively.11-13 Several authors highlight the importance of obturating lateral canals with the objective of promoting repair.4-6 Numerous publications demonstrate that the thermoplasticized techniques favor the obturation of the lateral and accessory canals.8,14,15 It is important to mention, as GulgenFilho, et al.,16 and Karabucak, et al.,17 that the different brands of gutta percha with diverse formulas behave in different manners due to the variations in fluidity. The use of thermoplasticized gutta-percha techniques generally allow the filling of the lateral canals with gutta percha; on the other hand, with the lateral condensation technique, the obturation of the lateral canals was achieved only with sealer.14,18,19 In this study, by using the single-cone technique and AH Plus sealer, 28 simulated lateral canals that were totally obturated were found to be filled with sealer. In the GuttaCore technique, within the 35 simulated lateral canals, 17 were obturated with sealer and 18 with gutta percha.

Comparative studies related to the obturation of root canals demonstrated that when GuttaCore was used, the mass of the gutta percha filled the irregularities more satisfactorily than the single-cone technique, which left a thinner film of sealer in the interphase.20,21 The cleared specimens allow for the distinguishing of the type of material that fills the simulated lateral canals.

DuLac, et al.,14 observed in a root canal system with lateral canals prepared in resin blocks that the carrier-based technique filled the cervical, middle, and apical third significantly better with gutta percha than lateral condensation. Wolcott, et al.,19 observed on resin models with simulated lateral canals that both techniques were equally effective in filling lateral canals, but there was significantly more gutta percha in the lateral canals with the gutta percha-coated rigid carrier technique. In contrast, the cold lateral 40 Endodontic practice

Table 1: Descriptive summary Third

Cervical

Middle

Apical

Category

Technique

Total

Single Cone

GuttaCore

NO

6

2

8

PO

2

1

3

TO

5

10

15

Total

13

13

26

NO

1

0

1

PO

1

0

1

TO

11

13

24

Total

13

13

26

PO

1

1

2

TO

12

12

24

Total

13

13

26

Figure 3: Postoperative radiograph and cleared specimen of group 1 showing the presence of sealer filling the lateral canals

Figure 4: Postoperative radiograph and cleared specimen of group 2 showing gutta-percha filling the lateral canals

condensation technique had significantly more sealer in the lateral canals. These findings were corroborated in the present study.

From a clinical point of view, it is important to highlight different authorsâ&#x20AC;&#x2122; statements that lateral canals may not be completely sealed even when radiographic images show a complete obturation. The penetration of the filling material in the lateral canal can give a false image.1,3,7,8 Therefore, in this study, the following categories were considered in the evaluation of radiographs: not obturated, partially obturated, and totally obturated. These radiographic results were confirmed with an analysis of the cleared specimens.

In relation to the caliber of the simulated lateral canals, these were drilled to a diameter of approximately 150Â Îźm, corresponding to

Engine Reamer No. 15. This caliber is related to what Kasahara, et al.,22 have observed in maxillary incisors and Miyashita, et al.,23 in mandibular incisors.

On the other hand, under in vivo conditions, organic debris that remains inside the lateral canals is difficult to remove through instrumentation and irrigation, and its presence can hinder the obturation of lateral and accessory canals. Hence, in this study, a paraffin gel was introduced inside the root canal previously instrumented and irrigated to simulate this situation Moreover, the roots of the specimens were covered with a thin foam rubber and Teflon to create a barrier to mimic the periodontal ligament.7,24,25 As Reader, et al.,18 and Goldberg, et al.,26 state, the accumulation of smear layer, produced during instrumentation, may block Volume 12 Number 1

Conclusion Simulated lateral canals were frequently obturated by both techniques, but in those obturated with GuttaCore, a tendency to fill the lateral canals with gutta percha was observed.

Acknowledgments Appreciation to Dr. Ricardo L. Macchi for his collaboration in the statistical evaluation. EP REFERENCES 1. Ricucci D, Loghin S, Siqueira JF Jr. Exuberant biofilm infection in a lateral canal as a cause of short-term endodontic treatment failure: report of a case. J Endod.

2013;39(5):712-718.

2. De Deus QD. Frequency, location, and direction of lateral, secondary, and accessory canals. J Endod.

1975;1(11):361-366.

3. Ricucci D, Siqueira JF Jr. Fate of tissue in lateral canals and apical ramifications in response to pathologic conditions and treatment procedures. J Endod. 2010,36(1):1-15.

4. Schilder H. Filling root canals in three dimensions. Dent Clin

North Am. 1967;11:723–744.

5. Seltzer S. Endodontology — biologic considerations in endodontic procedures. New York, NY: McGraw-Hill; 1971.

with different thermoplastic delivery systems. J Endod.

2008;34(7):847-849.

6. Weine F. The enigma of the lateral canal. Dent Clin North Am. 1984;28(4):833-852.

18. Reader CM, Himel VT, Germain LP, Hoen MM. Effect of three obturation techniques on the filling of lateral canals and the main canal. J Endod. 1993;19(8):404-408.

7. Almeida JF, Gomes BP, Ferraz CC, Souza-Filho FJ, Zaia AA. Filling of artificial lateral canals and microleakage and flow of five endodontic sealers. Int Endod J. 2007;40(9):692-699.

19. Wolcott J, Himel VT, Powell W, Penney J. Effect of two obturation techniques on the filling of lateral canals and main canal. J Endod. 1997;23(10):632-635.

8. Venturini M, Di Lenarda R, Prati C, Breschi L. An in vitro model to investigate filling of lateral canals. J Endod.

2005;31(12):877-881.

20. Goldberg F, Araujo JA. Estudio comparativo de la penetración de la gutapercha en las irregularidades del conducto radicular: sistema GuttaCore y técnica de cono único.

[Comparative study of gutta-percha penetration in the root canal irregularities: GuttaCore system and single cone technique.] Rev Asoc Odontol Argent. 2016;104(1):4-8.

9. Gutmann J. Innovative changes in core-carrier root canal obturation. Endodontic Practice US. 2012;5(2):36-41.

10. Canzani JH, Testa R, Garcia Fernandez E, Santía C. Transparencia de dientes. Su utilidad en la enseñanza preclínica de la endodoncia. [Tooth transparencies. Its use in the preclinical teaching of endodontics]. Rev Asoc Odontol Argent. 1984;72(3):72-73.

11. Gordon MP, Love RM, Chandler NP. An evaluation of .06 tapered gutta-percha cones for filling of .06 taper prepared curved root canals. Int Endod J. 2005;38(2):87-96.

12. Manfré S, Goldberg F. Evaluación del ajuste y adaptación de los conos de gutapercha ProTaper al conducto radicular instrumentado con el sistema ProTaper Universal. Endodoncia. 2010;28(3):135-140.

13. Chesler MB, Tordik PA, Imamura GM, Goodell GG. Intramanufacturer diameter and taper variability of rotary instruments and their corresponding gutta-percha cones. J Endod.

2013;39(4):538-541.

14. DuLac KA, Nielsen CJ, Tomazic TJ, Ferrillo PJ Jr, Hatton JF. Comparison of the obturation of lateral canals by six techniques. J Endod. 1999;25(5):376-380.

15. Goldberg F, Artaza LP, De Silvio A. Effectiveness of different obturation techniques in the filling of simulated lateral canals. J Endod. 2001;27(5):362-364.

16. Gurgel-Filho ED, Feitosa JP, Gomes BP, et al. Assessment of different gutta-percha brands during the filling of simulated lateral canals. Int Endod J. 2006;39(2):113-118.

17. Karabucak B, Kim A, Chen V, Iqbal MK. The comparison of gutta-percha and Resilon penetration into lateral canals

ng! o l r a e y l l A No limit!

21. Manzur E, Caplan V, Ballachino M, Goldberg F. Evaluación comparativa de la adaptación de la obturación endodóntica a las paredes del conducto radicular con dos técnicas de obturación. [Comparative evaluation of the adaptation of the endodontic obturation to the root canal walls with two filling techniques.] Rev Asoc Odontol Argent. 2016:104(3):95-101.

22. Kasahara E, Yasuda E, Yamamoto A, Anzai M. Root canal system of maxillary central incisor. J Endod.

1990;16(4):158-161.

23. Miyashita M, Kasahara E, Yasuda E, Yamamoto A, Sekizawa T. Root canal system of mandibular incisor. J Endod.

1997;23:479-484.

24. Goldberg F, Artaza LP, Alfie D. Capacidad de diferentes procedimientos de irrigación para la remoción del barro dentinario del orificio pulpar de conductos laterales simulados. Rev Asoc Odontol Argent. 2010:98:113-118.

25. de Gregorio C, Estevez R, Cisneros R, Paranjpe A, Cohenca.

Efficacy of different irrigation and activation systems on the penetration of sodium hypochlorite into simulated lateral canals and up to working length: an in vitro study. J Endod.

2010;36(7):1216-1221.

26. Goldberg F, Massone JE, Spielberg C. Effect of irrigation solutions on the filling of lateral root canals. Endod Dent Traumatol. 1986;2(2):65-66.

27. Villegas JC, Yoshioka T, Kobashayi Ch, Suda H. Obturation of accessory canals after four different final irrigation regimes. J Endod. 2002;28(7):534-536.

*Any 5 tün Ultrasonic Tips Any 5 Packs of Finishing Files Learn more at our new site:

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Volume 12 Number 1

Endodontic practice 41

RESEARCH

the entrance of the lateral canal. Due to this, EDTA 17% and EndoActivator were used in both samples to remove the smear layer.

The removal of the smear layer with EDTA facilitates the obturation of lateral and accessory canals.26,27

CONTINUING EDUCATION

The cortical window – part 1 Drs. Naheed Mohamed, Yosi Nahmias, and Ken Serota discuss the evolution of endodontic surgery in the first of this 2-part article

N

onsurgical endodontic therapy requires access preparations that uncover entrances to the labyrinthine tunnels of the root canal system. The era of bio-minimalism has altered the traditional configuration of endodontic access cavities. These bio-minimalistic trends are also transforming endodontic surgery (Wang, et al., 2004). The use of surgical operating microscopes (Global Surgical Corporation) facilitates smaller crypt sizes and reduces the volume of bone removed. The wound architecture created by microsurgical scalpels (Kerr Hawe) is more precise resulting in minimal damage to the soft tissues (Tsesis, et al., 2013). Enhanced visibility facilitates perpendicular resection of the apical segment to the long axis of the root. Monofilament sutures (Johnson & Johnson® Ethicon®) minimize posttreatment inflammation. Soft and hard tissue augmentation corrects deficits in biotype and buttressing bone. These are but a few of the new adjuncts in endodontic microsurgical techniques (Tsesis, et al., 2013; Kim and Katchman, 2006; Setzer, et al., 2012).

Ultrasonic osteotomy Used in both periodontal and implant surgery, piezo surgery in microsurgical endodontics produces micrometric cuts that diminish cortical bone loss and retain root length. Saline pumped through irrigation lines cools the piezotome tip (NSK, UK) (Figure 1).

In deep spaces, ultrasonic vibrations break down the irrigation into very small particles readily suctioned from the surgical field.

Reduction of heme in the crypt minimizes

Educational aims and objectives

This article aims to explain with illustrations the clinical reasons for the cortical window technique in endodontics.

Expected outcomes

Endodontic Practice US subscribers can answer the CE questions on page 49 to earn 2 hours of CE from reading this article. Correctly answering the questions will demonstrate the reader can: •

Identify when and how to perform the cortical window technique.

•

Identify some characteristics of piezo surgery in microsurgical endodontics.

•

Realize what part ultrasound plays in the piezo surgery process.

•

Recognize some drawbacks to traditional osteotomies.

•

Recognize the positive role of CBCT in the cortical window technique.

the use of hemostatic agents and interference with the setting of retro-seal materials.

The inclusion of piezo surgery in endodontic microsurgical protocols produces less morbidity during the healing phase.

Ultrasound consists of mechanical waves of frequencies greater than 20 kHz. Generated by transducers (lead zirconate titante), electrical energy is converted to ultrasonic waves with minimal heat production. The clinician controls the pressure applied, cutting frequency, pulse frequency, rate of delivery of coolant fluid, and power (3-90 watts).

Minimal heat generation on cutting creates lower proinflammatory cytokine levels, an earlier increase in BMP4 and TGF2 and more active neo-osteogenesis (Vercellotti, 2009; Abella et al, 2014).

Traditional osteotomies require large instruments to remove cortical bone in order to access the apical segment of the root. These instruments can lead to delayed

Naheed Mohamed, DMD, MSD, Perio, FRCD(c), is a board-certified periodontist and Diplomate of the American Academy of Periodontology. He is a partner in a group periodontal practice in Mississauga and maintains his own private practice in Oakville, Ontario. He can be reached at naheedm@gmail.com.

Yosi Nahmias, DDS, MSc, was born and raised in Mexico City. After he graduated from the Universidad Tecnologica de Mexico, School of Dentistry, in 1980, he decided to advance his education and chose endodontics as his specialty. Dr. Nahmias earned his Masters of Science degree in endodontics in 1983 at Marquette University in Milwaukee, Wisconsin. He has authored many articles and continues to lecture in Canada and internationally. Dr Nahmias has been a practicing endodontist in Oakville, Ontario, since 1983. He can be reached at yosi@allianceds.com.

Ken Serota, DDS, MMSc, graduated from the University of Toronto faculty of dentistry in 1973 and received his certificate in endodontics and Masters of Medical Sciences degree from the Harvard-Forsyth Dental Center in Boston, Massachusetts. Active in online education since 1998, he is the founder of the online forums Roots and Nexus. Dr. Serota is a clinical instructor in the University of Toronto postdoctoral endodontics department.

42 Endodontic practice

Figure 1: Piezotomes with fine-toothed saw tips of 8 mm and 10 mm length create smaller osteotomies and minimal osseous trauma (NSK; Brasseler USA®, Savannah, Georgia)

healing, increased postoperative pain, and/or complications. With microscopes and piezotome surgical tips, smaller osteotomies (less than 5 mm) are big enough to accommodate ultrasonic tips (tip length of 3 mm).

Cortical window technique Dental radiographs are essential to all aspects of endodontics. Historically, they were two-dimensional images of threedimensional structures; as such, data interpretation was subjective. The introduction of cone beam computed tomography (CBCT) and digital volume technology (DVT) provides images in sagittal, axial, and coronal planes showing previously indeterminable views (Venskutonis, et al., 2014; Leonardi Butra, et al., 2016). The three-dimensional data gathered from the CBCT scan allows a preplanned window to be made to access the apical portion of the roots. The use of CBCT imaging in conjunction with piezo surgery Volume 12 Number 1

Figure 2A: Cone beam tomography facilitates measurements of crypt dimension in sagittal, axial, and coronal views (x, y, z axes)

Figure 3: Tooth LL6. All canals are under-instrumented and demonstrate obturation density deficit. Retreatment of the tooth would necessitate removal of the cast post core, which could lead to fracture of the mesial and distal roots

provides a precise and less traumatic outline for the cortical bone window in contrast to traditional free-hand guided crypt creation.

The cortical bone window is sectioned so that the facial or palatal wall converges from the external surface to the internal surface.

This ensures accuracy of removal of the cortical bone plate and re-seating when the window is replaced.

Case report A female patient was seen for consultation regarding tooth LL6. She reported that pain on biting had developed over the past week and intensified day to day. Her generalist took a periapical radiograph and advised the patient that something was amiss. A prescription for amoxicillin (500 mg) was provided, and she was referred to our surgery. Tooth LL6 was percussion sensitive.

A two-dimensional radiographic examination revealed a prior root canal procedure, a PFM crown and cast post core in the mesialbuccal and distal canals. The suggestion of a second distal canal was noted (Figure 3).

A cone beam tomography scan was recommended as the tomographic volumes Volume 12 Number 1

Figure 4: The CBCT demonstrates a more definitive extent of the pathology. A sagittal view (CBCT) was used to determine the width and height of the cortical window required. The window cut is angled convergent from the external to the internal cortical plate, the base larger apically than coronally, thus preventing the bone segment from collapsing into the crypt when replaced

would elicit more accurate diagnostic information; the patient concurred, and was referred to a dental radiologist (www.canaray. com). The CBCT (Figure 4) showed that the apex of the distal root demonstrated rarefying osteitis. In addition, the apical third of the distal root was under-instrumented and under-filled, which contributed to persistent apical pathology. The mesial root appeared normal radiographically. Retreatment as an option was discussed, however, the risk factors involved, removal of the crown/ post core, and retreatment of the root canal system, were deemed have an uncertain prognosis. Other options were discussed including consideration for extraction and implant replacement. The patient agreed to have microsurgical treatment using a cortical bone window access â&#x20AC;&#x201D; a sagittal view (CBCT) was used to determine the width and height of the cortical window needed (Figure 2A). The coronal view shows the facial lingual

width and the position of the inferior alveolar nerve (Figure 2B) â&#x20AC;&#x201D; the relation of the lesion between facial and lingual cortical place determines depth of the surgical crypt and the its proximity to the inferior alveolar nerve.

The clinical examination identified generalized recession and diminished attached gingiva about the facial aspect of LL4 and the mesial root of LL6 (Figure 5A).

Anesthesia was obtained using Xylocaine 2% with epinephrine 1:100,000 (Dentsply Sirona) for the IAN (inferior alveolar nerve) and Xylocaine 2% with epinephrine 1:50,000 (Dentsply Sirona) was used for regional infiltration. A surgical operating microscope was used, and the principles of modern microsurgical endodontics (Vercellotti, 2009) were applied. A full thickness intra-sulcular flap was incised with a microsurgical blade, which minimizes trauma and loss of the interdental dental papilla especially in areas of recession and thin biotype (Figure 5B). The piezotome Endodontic practice 43

CONTINUING EDUCATION

Figure 2B: Proximity to the inferior alveolar nerve can be calculated. This is a crucial measurement in all microsurgical procedures

CONTINUING EDUCATION

Figures 5A and 5B: The flap is designed to correct the areas of recession. Vertical and horizontal incisions present pressure of the flap on retraction. The roots were planed to ensure a clean surface, enhancing improved adherence of flap to the root

Figure 7: The cortical window was removed with a fine chisel

Figure 6: The piezotome (VarioSurg 3; NSK) creates an osseous window that will be replaced after completion of the root end surgery

Figure 8: A truss is retained between the two roots to expedite osseous regeneration. The retroseals (SuperEBAÂŽ) are burnished and the root face polished with a multi-fluted carbide bur

Figure 10: The cortical bone plate is replaced over the access window

Figure 11: The flap is co-apted and sutured to place. Note that the areas of recession are covered with tissue

Figure 9: Allograft is placed in the crypt 44 Endodontic practice

Volume 12 Number 1

was used to cut the cortical window. The cortical window was angled convergent from the external surface to the internal surface and wider at the base, which prevents the plate from sinking internally when repositioned as discussed previously (Figure 6).

The window was removed by luxation (Figure 7) from a thin chisel and placed in sterile saline. The apices are resected at a 0º angle preserving root length exposing the lingual anatomy, centering the canals, eliminating accessory canals, and minimizing the number of exposed dentinal tubules.

The canal is retro-prepared (ProUltra® tips, Dentsply-Sirona) retro-sealed using Super EBA (Keystone Dental) (Sullivan, et al., 1999) (Figure 8).

The crypt is filled with freeze-dried allograft (0.5 cc Mineralized Cortical GC, Straumann®) (Figure 9). The cortical window is replaced (Figure 10) and the wound (flap) sutured using 6-0 prolene sutures (Ethicon®) (Figure 11). The postoperative radiograph is shown (Figure 12). The reassessment radiograph taken 6 months later demonstrates almost complete osseous regeneration (Figure 13). The patient is asymptomatic, the procedure has retained substantial root length, and a long-term positive treatment outcome is expected (Figure 14).

Conclusion The basic framework of endodontic surgery by incorporation of interdisciplinary precepts has evolved into endodontic microsurgery. The benefits of this cortical window approach include greater access the roots for better visibility without greater risk for bone loss. The minimally invasive approach Volume 12 Number 1

Figure 13: Six-month recall appointment shows healing to be almost complete

Figure 14: Six-month follow-up showing clinical healing and healthy tissue response

to access the roots by way of removal of a cortical bone plate has its greatest advantage simply due to the fact that the bone plate is conserved and then replaced, allowing maximum regenerative potential. Advances in the surgical armamentarium, based on biological concepts has enabled a microsurgical approach, which ensures enhanced positive treatment outcomes. The past is not being rejected; the future is being embraced.

It is the natural progression of all things. EP

REFERENCES 1. Abella F, de Ribot J, Doria G, Duran-Sindreu F, Roig M. Applications of piezoelectric surgery in endodontic surgery: a literature review. J Endod. 2014;40(3):325-332.

2. Leonardi Dutra K, Haas L, Porporatti AL, et al. Diagnostic accuracy of cone-beam computed tomography and

conventional radiography on apical periodontitis: a systematic review and meta-analysis. J Endod. 2016;42(3):356-364.

3. Kim S, Kratchman S. Modern endodontic surgery concepts and practice: a review. J Endod. 2006;32(7):601-623.

4. Setzer FC, Kohli MR, Shah SB, Karabucak B, Kim S. Outcome of endodontic surgery: a meta-analysis of the literature — Part 2: Comparison of endodontic microsurgical techniques with and without the use of higher magnification.

J Endod. 2012;38(1):1-10.

5. Sullivan JE Jr, Da Fiore PM, Heuer MA, Lautenschlager EP, Koerber A. Super-EBA as an endodontic apical plug. J Endod. 1999;25(8):559-561.

6. Tsesis I, Rosen E, Taschieri S, et al. Outcomes of surgical endodontic treatment performed by a modern technique: an updated meta-analysis of the literature. J Endod.

2013;39(3):332-339.

7. Venskutonis T, Plotino G, Juodzbalys G, Mickevičienė L. The importance of cone-beam computed tomography in the management of endodontic problems: a review of the literature. J Endod. 2014;40(12):1895-1901.

8. Vercellotti T. Essentials in Piezosurgery: Clinical Advantages in Dentistry. Italy: Quintessence Publishing; 2009.

9. Wang N, Knight K, Dao T, Friedman S. Treatment outcome in endodontics — The Toronto Study. Phases I and II: apical surgery. J Endod. 2004;30(11):751-761.

Endodontic practice 45

CONTINUING EDUCATION

Figure 12: Posttreatment radiograph

CONTINUING EDUCATION

Mandibular first molar with four canals in the mesial root Drs. Hamed Karkehabadi, Ricardo Machado, and Lucas da Fonseca Roberti Garcia describe a case report of a mandibular first molar showing the presence of four canals in the mesial and two canals in the distal root Abstract A 35-year-old female patient with intermittent pain in the lower right jaw was referred to the dental practice. The right mandibular first molar did not respond to thermal testing, and the patient reported moderate pain to percussion and palpation in the region of this tooth. Radiographic findings confirmed the presence of periradicular disease and previous root canal treatment. Initially, only four treated canals were found (two mesial and two distal). Two extra canals were found in the mesial root. The treatment was performed and the success confirmed after 12 months. This case report reiterates the complexity of mandibular first molar variation and is intended to reinforce the clinicians’ need to be aware of the variable morphology of root canals in this tooth.

Introduction The goal of endodontic treatment is to clean and shape the root canal system and obturate it in all its dimensions (Almeida, et al., 2015). Before starting treatment, aberrant root or root canal morphology should be investigated, detected, and adequately treated (Lea, et al., 2014). Failure to recognize any unusual canal configuration could eventually lead to an unsuccessful treatment outcome (Almeida, et al., 2015; Lea, et al., 2014; Ghoddusi, et al., 2007). Thus, the proper knowledge of the root and root canal morphology, along with any related anatomical variations, is essential to achieve a successful treatment (Almeida, et al., 2015; Lea, et al., 2014; Ghoddusi, et al., 2007).

Ricardo Machado runs a clinical practice limited to endodontics in Navegantes, Santa Catarina, Brazil.

Hamed Karkehabadi works in the department of endodontics of the dental school, Hamadan University of Medical Sciences, Hamadan, Iran.

Lucas Da Fonseca Roberti Garcia works in the department of dentistry — endodontics division, Federal University of Santa Catarina, Florianópolis, Santa Catarina, Brazil.

46 Endodontic practice

Educational aims and objectives

This article aims to illustrate how to treat a first molar showing the presence of four canals in the mesial and two canals in the distal root.

Expected outcomes

Endodontic Practice US subscribers can answer the CE questions on page 49 to earn 2 hours of CE from reading this article. Correctly answering the questions will demonstrate the reader can: •

Identify some hints and tips to successfully treatment teeth with multiple roots.

•

Identify some statistics on mandibular first molars.

•

Realize the unusual nature of a mandibular first molar with four canals in the mesial root.

•

Realize the importance of having a good understanding of the canal anatomic complexities to achieve effective disinfection of the root canal system.

•

Recognize some imaging technologies that can be used, when appropriate, as an adjunctive tool for detection and management of variable root canal morphology.

Mandibular first molars are the teeth that most require endodontic treatment, as they are the first posterior teeth to erupt in permanent dentition (Ghoddusi, et al., 2007). Although mandibular first molars usually have two canals in the mesial root, named as mesiobuccal and mesiolingual canals, the presence of a middle mesial canal in the developmental groove has been widely reported in 1% (Vertucci, 1964), 1.5% (Martinez-Berna and Badanelli, 1983), 2.1% (Fabra-Campos, 1985), 2.6% (Fabra-Campos, 1989), 12% (Pomeranz, et al., 1981), 14.7% (Akbarzadeh, et al., 2017), 15% (Goel, et al., 1991), and 18.6% (Versiani, et al., 2016) of the cases. In addition, mandibular first molars may have one or two canals in the distal root (Ghoddusi, et al., 2007).

As reported in several studies, the prevalence of a middle mesial canal in mandibular first molars may significantly range among researchers. Clinical studies and case reports that demonstrated the presence of negotiable middle mesial canals present different data from studies which used extracted teeth model (Vertucci, 1984; Martinez-Berna and Badanelli, 1983; Fabra-Campos, 1985; Fabra-Campos, 1989; Pomeranz, et al., 1981; Akbarzadeh, et al., 2017; Goel, et al., 1991; Versiani, et al., 2016).

To the best of the authors’ knowledge, just one case has ever been reported in the scientific literature of a mandibular first molar with four canals in the mesial root (Reeh, 1998). In this particular case, the author reported a successful endodontic retreatment of a mandibular first molar with seven canals, where the other three canals were located in the distal root. Initially, the clinician failed in detect the complexity of the root canal system of this tooth, and only three canals were submitted to endodontic treatment. Such factor demonstrates the importance of knowing the root canal system morphology and its anatomical variations (Reeh, 1998). Furthermore, according to the author of the case report, looking for additional canals was crucial for a successful outcome (Reeh, 1998).

Therefore, the aim of this article is to report a clinical case of a mandibular first molar with four canals in the mesial root and two canals in the distal root. All canals were properly prepared and filled, and the success of the treatment was confirmed after 12 months by clinical and radiographic findings.

Case report A 35-year-old female patient, with a history of intermittent pain in the lower right jaw 3 weeks previous to being seen, was Volume 12 Number 1

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CONTINUING EDUCATION

referred to the dental practice. Medical history was non-contributory. The right mandibular first molar did not respond to thermal testing (heated gutta percha and dry ice), and the patient reported moderate pain to percussion and palpation in the region of this tooth.

Furthermore, the tooth had a total crown, and there was no significant probing depth.

Radiographic findings confirmed the presence of periradicular disease and previous root canal treatment (Figure 1A). Correlation of clinical and radiographic findings led to a diagnosis of a chronic periradicular abscess due to previous unsuccessful endodontic treatment. Therefore, a nonsurgical root canal retreatment was recommended.

After administrating infiltration anesthesia (Lidocaine 2% 1:80.000 epinephrine), the crown was removed, and rubber dam isolation of the operative area was performed. An endodontic access cavity was prepared by using 1016HL and Endo Z burs (Dentsply Sirona Maillefer), and four previously treated root canals were found. Removal of root canal filling was performed by using a Neoniti A1 size 20 file (Neolix, Châtres-laForêt, France). After a careful analysis of the floor of the pulp chamber, two additional root canals were found in the mesial root, totaling four canals in this root. Initially, extra canals were explored with a size 10 K-File (Mani, Inc; Tochigi, Japan) under copious irrigation with 5.25% sodium hypochlorite solution (Chloraxid, Cerkamed, Poland). Next, the working length of each root canal was established 1 mm up to the apical foramen, by using an electronic apex locator (Root ZX, Morita, Tokyo, Japan). Then a radiograph was taken to confirm the measurements (Figure 1B). The chemo-mechanical preparation was performed by the crown-down technique, with the Neoniti system (Neolix).

The first four root canals found (MB1, ML1, DB, and DL) were prepared up to a Neoniti A1 size 25 file (Neolix). The two additional root canals found in the mesial root (MB2 and ML2) were prepared up to a Neoniti A1 size 20 file. Irrigation was performed with 2.5 ml of 5.25% sodium hypochlorite solution (Chloraxid) at each change of file, by using a 30-gauge, open-ended needle (Navitip®; Ultradent®, South Jordan, Utah) placed slightly short of the binding point. After a final rinse with MTAD (Dentsply Tulsa), the root canals were dried with sterile absorbent paper points (Dentsply Maillefer, Ballaigues, Switzerland), and a radiograph was taken of the main cones to confirm if they reached the working length (Figure 1C). Afterwards, the canals were filled with gutta percha (Dentsply

Figures 1A-1H: A. Initial radiograph. B. Radiographic working length confirmation. C. Radiograph of main cones. D-F. Final radiographs. G-H. Radiographs of 12-month follow-up Endodontic practice 47

CONTINUING EDUCATION Maillefer, Ballaigues, Switzerland) and AH Plus® sealer (Dentsply DeTrey, Ballaigues, Switzerland), using the lateral condensation technique. The pulp chamber was properly cleaned to remove the excess of gutta percha and sealer, and it was temporarily restored with a provisional material (Figures 1D-1F).

Clinical and radiographic findings, as there was no painful symptomatology and regression of the periapical lesion, confirmed the success of the proposed therapy.

Continued follow-up over 12 months has shown a positive outcome from an endodontic perspective (Figures 1G and 1H).

Discussion The prevention and treatment of apical periodontitis are the main objectives of endodontic therapy (Siqueira and Rôças, 2008). An adequate biomechanical preparation and filling of the root canal system, associated with the placement of a proper coronal sealing, are crucial and should be taken to achieve this goal (Gillen, et al., 2011). Furthermore, all these steps performed during the treatment require a good understanding of the root canal anatomy to attain a successful outcome (Reeh, 1998).

The purpose of this article was to present the case report of a mandibular first molar clearly showing the presence of four canals in the mesial root and two canals in the distal root. The patient was referred to the dental practice because of the persistent symptoms after the first endodontic treatment, at which time, only four root canals were located and treated (two in the mesial root and two in the distal root).

The clinician should keep in mind that the internal morphology of the teeth does not always follow the known standards (Almeida, et al., 2015; Lea, et al., 2014). In this clinical case, the incomplete debridement of the six root canals probably was the cause for the occurrence and perpetuation of the periradicular disease (Reeh, 1998). Once all the root canals were located and could be properly negotiated, shaped, and cleaned, the symptoms disappeared, and a 12-month follow-up X-ray showed the consistent healing of the periapical alveolar bone. To locate additional root canals can be a challenging procedure for professionals; for this reason, the findings reported in this clinical case highlight how important it is to have a good understanding of the canal anatomic complexities to achieve effective disinfection of the root canal system (Siqueira and Rôças, 2008).

48 Endodontic practice

The clinician should always suspect the presence of additional root canals and investigate further when examining radiographs and/or locating and exploring the canals (Johal, 2001). Although there are inherent limitations, radiographic examination provides a clue to the type of canal configuration present (Hildebolt, et al., 1990).

Previous reports have continuously used imaging technologies, such as spiral computed tomography (SCT) (Gopikrishna, et al., 2006; Aggarwal, et al., 2009) and cone-beam computed tomography (CBCT) (Almeida, et al., 2015; Lea, et al., 2014), as an adjunctive tool for detection and management of variable root canal morphology.

These imaging technologies may be helpful in detecting variations of root canals in doubtful circumstances related to unusual root canal anatomy (Gopikrishna, et al., 2006; Aggarwal, et al., 2009; Almeida, et al., 2015; Lea, et al., 2014). Although these imaging modalities offer an insight into the anatomical variations of the root or root canal configuration, they also potentially increase the effective dose of radiation exposure for the patient, often limiting their use (Patel, et al., 2009).

The ALARA (as low as reasonably achievable) principle states that every effort should be made by professionals to keep the patient’s exposure to ionizing radiation as low as practically possible (Farman, 2005).

As reported in the present clinical case, the use of radiographic examination associated to an adequate clinical inspection of the floor of the pulp chamber was enough to depict the variable anatomy clearly. For this reason, advanced imaging techniques (SCT and CBCT) did not have to be used to solve this clinical case.

It is also valid to emphasize that other equipment, such as operative microscopes, may be used to facilitate the location and negotiation of additional root canals, improving significantly the quality of the endodontic therapy. Relvas, et al. (2013), have reported a successful endodontic treatment of a maxillary first premolar with three root canals, with the aid of an optical microscope. The authors stated that the use of such technology was fundamental to allow the location of the third root canal, due to the complex internal anatomy of the tooth (Relvas, et al., 2013).

This article provides useful clinical information for performing endodontic therapy in a very complex case, thus contributing to the awareness of another anatomic variant of mandibular molars.

Conclusions Reports of cases with unusual morphology have an important didactic value. Their documentation may facilitate the recognition and successful management of similar cases, which may require endodontic therapy. This case report reiterates the complexity of mandibular first molar variation and is intended to reinforce the clinicians’ need to be aware of the variable morphology of root canals in this tooth. EP

REFERENCES 1. Aggarwal VL, Singla M, Logani A, Shah N. Endodontic management of a maxillary first molar with two palatal canals with the aid of spiral computed tomography: a case report. J Endod. 2009;35(1):137-139.

2. Akbarzadeh N, Aminoshariae A, Khalighinejad N, et al. The Association between the Anatomic Landmarks of the Pulp Chamber Floor and the Prevalence of Middle Mesial Canals in Mandibular First Molars: An In Vivo Analysis. J Endod.

2017;43(11):1797-1801.

3. Almeida G, Machado R, Sanches Cunha R, Vansan LP, Neelakantan P. Maxillary first molar with 8 root canals detected by CBCT scanning: a case report. Gen Dent.

2015;63(2):68-70.

4. Fabra-Campos H. Unusual root anatomy of mandibular first molars. J Endod. 1985;11(12):568-572.

5. Fabra-Campos H. Three canals in the mesial root of mandibular first permanent molars: a clinical study. Int Endod J. 1989;22(1):39-43.

6. Ghoddusi J, Naghavi N, Zarei M, Rohani E. Mandibular first molar with four distal canals. J Endod.

2007;33(12):1481-1483.

7. Goel NK, Gill KS, Taneja JR. Study of root canals configuration in mandibular first permanent molar. J Indian Soc Pedod Prev Dent. 1991;8(1):12-14.

8. Lea C, Deblinger J, Machado R, Nogueira Leal Silva EJ, Vansan LP. Maxillary premolar with 4 separate canals. J Endod. 2014;40(4):591-593.

9. Martinez-Berna A, Badanelli P. Investigacion clinica de molars inferiors con cinco conductos. Boletin de Informacion Dental. 1983;43:27-31 10. Pomeranz HH, Eidelman DL, Goldberg MG. Treatment considerations of the middle mesial canal of mandibular first and second molars. J Endod. 1981;7(12):565-568.

11. Reeh ES. Seven canals in a lower first molar. J Endod.

1998;24(7):497-499.

12. Siqueira JF Jr, Rôças IN. Clinical implications and microbiology of bacterial persistence after treatment procedures.

J Endod. 2008;34(1):1291-1301.

13. Gillen BM, Looney SW, Gu LS, et al. Impact of the quality of coronal restoration versus the quality of root canal fillings on success of root canal treatment: a systematic review and meta-analysis. J Endod. 2011;37(7):895-902.

14. Gopikrishna VL, Bhargavi N, Kandaswamy D. Endodontic management of a maxillary first molar with a single root and a single canal diagnosed with the aid of spiral CT: a case report. J Endod. 2006;32(7):687-691.

15. Hildebolt CF, Vannier MW, Pilgram TK, Shrout MK. Quantitative evaluation of digital dental radiograph imaging systems.

Oral Surg Oral Med Oral Pathol. 1990;70(5):661-668.

16. Johal S. Unusual maxillary first molar with 2 palatal canals within a single root: a case report. J Can Dent Assoc.

2001;67(4):211-214.

17. Patel S, Dawood A, Whaites E, Pitt Ford T. New dimensions in endodontic imaging: part 1. Conventional and alternative radiographic systems. Int Endod J. 2009;42(6):447-462.

18. Farman AG. ALARA still applies. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2005;100(4):395-397.

19. Relvas JB, de Carvalho FM, Marques AA, Sponchiado EC Jr, Garcia Lda F. Endodontic treatment of maxillary premolar with three root canals using optical microscope and NiTi rotatory files system. Case Rep Dent. 2013;710408.

20. Versiani MA, Ordinola-Zapata R, Keleş A, et al. Middle mesial canals in mandibular first molars: A micro-CT study in different populations. Arch Oral Biol. 2016;61:130-137.

21. Vertucci FJ. Root canal anatomy of the human permanent teeth. Oral Surg Oral Med Oral Pathol. 1984;58(5):589-599.

Volume 12 Number 1

REF: EP V12.1 MOHAMED, ET AL. REF: EP V12.1 KARKEHABADI, ET AL.

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The cortical window — part 1

Mandibular first molar with four canals in the mesial root

MOHAMED, ET AL.

KARKEHABADI, ET AL.

1.

2.

The use of surgical operating microscopes _____. a. facilitates smaller crypt sizes b. reduces the volume of bone removed c. corrects deficits in biotype d. both a and b Used in both periodontal and implant surgery, piezo surgery in microsurgical endodontics produces micrometric cuts that ________. a. maximize posttreatment inflammation b. diminish cortical bone loss c. retain root length d. both b and c

3.

________ pumped through irrigation lines cools the piezotome tip. a. Ethylenediaminetetraacetic acid (EDTA) b. Sodium hypochlorite c. Saline d. Chlorhexidine

4.

Ultrasound consists of mechanical waves of frequencies greater than ______. a. 5 kHz b. 10 kHz c. 14 kHz d. 20 kHz

5.

6.

(In an ultrasonic osteotomy) The clinician controls ________, rate of delivery of coolant fluid, and power (3-90 watts). a. the pressure applied b. the cutting frequency c. the pulse frequency d. all of the above Traditional osteotomies require ________ to remove cortical bone in order to access the apical segment of the root. a. microsurgical instruments

Volume 12 Number 1

b. large instruments c. tapered instruments d. piezotome surgical tips 7.

8.

9.

The introduction of __________ provides images in sagittal, axial, and coronal planes showing previously indeterminable views. a. cone beam computed tomography (CBCT) and digital volume technology (DVT) b. digitized 2D radiography c. panoramic imaging d. operating microscopes The patient agreed to have microsurgical treatment using a cortical bone window access — a/an ________was used to determine the width and height of the cortical window needed. a. sagittal view (CBCT) b. 2D digital radiograph c. axial view (CBCT) d. coronal view (CBCT) (For this patient) The apices are resected at a _______ preserving root length exposing the lingual anatomy, centering the canals, eliminating accessory canals, and minimizing the number of exposed dentinal tubules. a. 0º angle b. 30º angle c. 45º angle d. 60º angle

10. The minimally invasive approach to access the roots by way of removal of a cortical bone plate has its greatest advantage simply due to the fact that the bone plate is ________, allowing maximum regenerative potential. a. replaced and then conserved b. conserved and then replaced c. cooled d. none of the above

1.

Before starting (endodontic) treatment, aberrant root or root canal morphology should be _____. a. investigated b. detected c. adequately treated d. all of the above

2.

Mandibular first molars are the teeth that most require endodontic treatment, as they are the ________ to erupt in permanent dentition. a. first posterior teeth b. last posterior teeth c. most difficult d. least likely

3

In addition, mandibular first molars may have ________ canals in the distal root. a. one b. two c. three d. both a and b

4.

The prevention and treatment of _______ are the main objectives of endodontic therapy. a. condensing osteitis b. apical periodontitis c. peri-implantitis d. external resorption

5.

6.

The clinician should keep in mind that the internal morphology of the teeth ________ follow(s) the known standards. a. always b. does not always c. must d. naturally Previous reports have continuously used imaging technologies, such as ________ as an adjunctive tool for detection and management of variable root canal morphology. a. spiral computed tomography (SCT) b. cone-beam computed tomography (CBCT)

c. near infrared transillumination (NIR) d. both a and b 7.

Although these imaging modalities offer an insight into the anatomical variations of the root or root canal configuration, they also ________, often limiting their use. a. are extremely expensive b. are extremely difficult for the clinician to interpret c. potentially increase the effective dose of radiation exposure for the patient d. offer misleading data

8.

The _________ principle states that every effort should be made by professionals to keep the patient’s exposure to ionizing radiation as low as practically possible. a. ALARA (as low as reasonably achievable) b. NORM (naturally occurring radioactive materials) c. DM (defensive medicine) d. CAP (choice of appropriate procedure)

9.

It is also valid to emphasize that several other pieces of equipment, such as ________, may be used to facilitate the location and negotiation of additional root canals, improving significantly the quality of the endodontic therapy. a. operative microscopes b. lasers c. intraoral cameras d. fluorescence

10.

Relvas, et al. (2013), have reported a successful endodontic treatment of a maxillary first premolar with three root canals, with the aid of ________. a. a medical CT b. a loupe c. an optical microscope d. an intraoral camera

Endodontic practice 49

CE CREDITS

ENDODONTIC PRACTICE CE

ENDODONTIC INSIGHT

Endodontic retreatment utilizing a conservative gutta-percha removal instrument Dr. Nishan Odabashian discusses how this instrument benefits his retreatment process

A

ccording to the American Dental Association publication 2005-06 Survey of Dental Services Rendered, approximately 22.6 million endodontic procedures were performed each year of the survey.1 Over the next decade, that number increased to closer to 25 million endodontic procedures annually. Initial endodontic treatment success is reported in the endodontic literature with a wide range from a low of 59% to a high of 95%.2,3 That translates to a failure rate of approximately 5% to 40%! Even if we consider a more conservative 10% failure rate, considering that there are more studies demonstrating success range of initial endodontic treatment to be closer to 90%, that translates to 2.5 million retreatment cases — less those that are planned for surgery or extracted. These numbers are corroborated when the clinician considers the percentage of teeth that are retreated in the private endodontic office. As an example, my practice consists of 60% initial endodontic treatment and 40% of endodontic retreatment. This is likely because I’m a specialist and am referred retreatment-type cases rather than initial root canal treatment.

Several years ago, as I walked through the Exhibit Hall at the American Association of Endodontists Annual Meeting, I came across a gutta-percha removal instrument at the DenMat booth. At first glance, it looked like an endodontic explorer; but on closer examination, I observed it had small hooks at each end (Figure 3). I was intrigued and purchased a set; upon return to my practice, I fell in love with the instruments after the first use.

Removing existing gutta percha from previously treated root canals can be accomplished several ways. This includes using a Gates Glidden bur to remove the coronal part of the gutta percha; using a GPX file, soaking the

Nishan Odabashian, DMD, MS, is a graduate of Tufts University School of Dental Medicine. After 8 years of practicing restorative dentistry, he pursued his specialty training in endodontics at Loma Linda University School of Dentistry (LLUSD), Department of Graduate Endodontics. He is part-time faculty at LLUSD, and practices microscope-aided restorative endodontics in Glendale, California.

Disclosure: Dr. Odabashian is a key opinion leader for this instrument and received financial compensation for this article.

50 Endodontic practice

Figure 1

Figure 2

Figure 3

canal with chloroform and using hand K-type or Hedstrom files; or using a heating System B® or similar instruments. Every method has its unique advantages and disadvantages.

The beauty of using the DenMat GuttaPercha Removal Instrument is that it eliminates the majority of the disadvantages of the previously mentioned methods. It maintains the size of the canal as is; greatly reduces the amount of chloroform used, specifically in the coronal two-thirds of the canal; and saves time in the gutta-percha removal process of retreating a failing root canal treatment.

Simply by heating the gutta percha using heating pluggers (e.g., System B), the instruments, which have the hooks pointing in four different directions (two on each instrument), are introduced to remove the gutta percha from the canals by latching on to the softened gutta percha (Figure 1) and pulling against the inner wall of the tooth. The DenMat Gutta-Percha Removal Instruments come in two lengths for both regular length and longer canals (Figure 2).

Tooth conservation during root canal treatment continues to gain importance among restorative and endodontic community as well as our patients. As such, I favor

the use of these DenMat instruments during root canal retreatment. Additional uses of this conservative instrument are removal of pulp tissue; removal of the cotton pellet or endo sponge during the second appointment in multi-visit endodontic cases; removal of loose dentin chips that lodge into the prepared canal; and, in the rare case of a separated instrument being loose in the canal, the ability to insert the gutta-percha instrument hook alongside of the SI and remove it.

I have come to use the instrument on so many occasions, that it is now part of my routine endodontic setup. I am confident that the DenMat Gutta-Percha Removal Instrument and implemented as part of the regular endodontic tray setup for anyone performing retreatment and/or conservative endodontics. EP REFERENCES 1. American Dental Association. ADA, Survey of Services Rendered, 2005-2006. Available at: http://ebusiness. ada.org/productcatalog/1428/Dentistry/200506-Surveyof-Dental-Services-Rendered-Downloadable-SC/SDSR2006D. Accessed January 30, 2019.

2. Jokinen MA, Kotilainen R, Poikkeus P, Poikkeus R, Sarkki L. Clinical and radiographic study of pulpectomy and root canal therapy. Scand J Dent Res. 1978;86(5):366-373.

3. Eriksen HM. Endodontology — epidemiologic considerations. Endod Dent Traumatol. 1991;7(5):189-195.

Volume 12 Number 1

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PRACTICE MANAGEMENT

How to increase your clinical efficiency and profitability Dr. Albert (Ace) Goerig discusses three main areas that may need change in your practice

H

ow is your office doing compared to last year? Most endodontists I talk with are working harder, have lower profitability, are getting fewer and tougher cases, and have greater stress in their practice. By improving office systems and efficiency, most endodontists can significantly reduce their stress and complete one or two more cases per day, which would double their net profit. Even though most endodontists can complete a molar treatment in 1 hour, I have found that the average endodontist completes three to four cases a day. To determine the number of cases you do in the day, take the number of cases you did last year, and divide by the number of days you worked.

Nothing will change from last year unless you change three main areas in your practice: 1. Marketing 2. Scheduling 3. Clinical focus

Marketing Most endodontists do minimal marketing, which is the key to practice growth. One of my favorite quotes about marketing is, “Those who need to market should not, and those who don’t need to market should.”

You should not market until you have an incredible, caring team that can create the WOW experience, have a clean and up-todate facility, are committed to seeing patients on time and completing on time, are clinically efficient and strive for excellence, and have openings each day to see emergency patients. When these are in place, then you can start a vigorous marketing plan.

Most marketing plans fail because they are inconsistent and devote too little time to marketing. They have no marketing coordinator and very few strategies. The doctor does not spend enough time creating relationships with his referring doctors and does not commit 2% to 3% of the revenue on marketing.

Albert (Ace) Goerig, DDS, MS, is a nationally known speaker who has lectured extensively in his field of endodontics and dental practice management to dentists throughout the United States, Canada, and abroad. He has authored over 60 articles and is a contributing author to the following textbooks: Pathways of the Pulp, Ingle’s Endodontics, and Practical Endodontics. Dr. Goerig is a Diplomate of the American Board of Endodontics and a Fellow of both the American and International College of Dentists. He has been involved in teaching both endodontics and general dentistry residents for many years. He is in private dental practice in Olympia, Washington, specializing in endodontics. In 1996, he co-founded Endodontic Practice Mastery to teach endodontists the business of dentistry while helping them to love their practice. Since then he has personally coached over 22% of all endodontists and their teams in the U.S. and Canada. He is also the co-author of Time and Money: Your Guide to Financial Freedom. He and his wife, Nancy, were married in 1969 and have five children. He has many hobbies, including fishing, scuba diving, skiing, and travel.

52 Endodontic practice

It is important to assign one of your administrative team members as a marketing coordinator who will be responsible for implementing and managing the marketing program and strategies. Every endodontist needs to create a referral tracking monitor to track the statistics daily, monthly, and yearly.

I believe that you need to connect with your important offices each month. In my practice, we go to over 80 offices a month. The marketing coordinator should spend about 12-18 hours per week on these duties. Meet with your marketing coordinator and office manager once a month to review the statistics to ensure the practice is headed in the right direction. Or, conversely, if it’s not headed in the right direction, identify ways to turn it around.

Scheduling To create an ideal schedule, you must first time yourself in various procedures and sit down with your team to give yourself adequate time to complete each case.

Initially, reduce most side bookings, such as diagnosis and emergencies, and leave space open at the end of the day for emergencies, which will become completed cases.

When emergency cases are next to treatment, there is not enough time to complete treatment. Many doctors spend too much time on the phone or computer, on team Volume 12 Number 1

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advantage needed to keep and increase your referrals

• Work efficiently and effortlessly and quit wasting 2-3 hours of your day

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Dr. Ace Goerig

PRACTICE MANAGEMENT management issues, or just talking too much. Set goals of cases completed each day, and at the end of the day, review the schedule flow with your team leaders, and make appropriate corrections for the next day. It is important that the administrative team understands which patients really need treatment and which should be placed in an evaluation appointment. Time must be taken to educate the administrative team on endodontic triage on endodontic diagnosis.

Clinical focus Endodontists must focus 98% of their time on direct patient treatment delivery and empower the team to manage the practice and stop wasting 4 to 6 hours a week on practice management. If you empower your team to run your practice, you need only 3 to 4 hours per month for business management.

Clinical efficiency comes from experience and having a step-by-step system of endodontic protocol. This helps your

Ego and perfectionism are the enemies of excellence, keep us upset, and prevent us from focusing on exactly what we need to do to solve the problem. assistants to work hand-in-hand with you, allowing the procedure to flow effortlessly.

Don’t lose your focus when you cannot find a canal or get down to length, or even perforate; just know that everything will come together. It is a mindset. When things are not going exactly the way you want, don’t get upset; instead, laugh or use the following words and phrases to refocus and stay on task: “Great!”; “Next!”; “Isn’t that interesting? “or “It is what it is.” Frustration and anger are detrimental in obtaining high quality clinical results and creating a fun and

profitable office. Ego and perfectionism are the enemies of excellence, keep us upset, and prevent us from focusing on exactly what we need to do to solve the problem.

It also affects our focus on the next patients we see, reducing the quality of care we give our patients.

When the systems really flow well, patients love being in the office, the team loves serving the patients, referrals go up, and endodontics becomes effortless, making the practice fun and profitable. Learn to enjoy the process. EP

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54 Endodontic practice

Volume 12 Number 1

PRODUCT PROFILE

Built to Last. Built for You. Built by Boyd.

“B

uilt to Last. Built for You. Built by Boyd” is more than a tagline; it signifies the commitment that everyone at Boyd makes to each and every one of our customers. Best known for the durability and reliability of our award-winning products — including treatment chairs, mobile storage, and clinical cabinetry — we combine over 60 years of design and manufacturing expertise to perfectly fit your unique space and personal style. The Boyd team takes great pride in the craftsmanship and longevity of all products built at our U.S.-based facility, so you can take pride in your office for years to come.

Featured product: S3100LC Endodontic Treatment Chair

Designed specifically for your needs, the S3100LC chair for endodontists combines ergonomic, reliable functionality with elegant design. Like the majority of Boyd Industries’ products, the S3100LC chair can be personalized to best suit your office, just as its design will best suit your specialization’s needs.

What makes the S3100LC design unique?

• It features a lockable swivel base — capable of 90 degrees of rotation from center — for patient positioning and entry/egress.

• Its lift column base allows the S3100LC chair to be raised or lowered in a fixed field of view.

• The tapered back design facilitates closer assistant positioning while maintaining patient comfort.

• A low profile, double-articulating headrest ensures proper positioning of the patient’s head.

• Easy-to-access membrane switches are located on left and right chair sides to control both base and back adjustments.

These come with three programmable settings for one-touch control to articulate the chair to frequently used positions, with a “Home” button that returns the chair to the lowered, upright position for patient egress.

• Ultraleather Pro™ fabric and memory foam come standard to support maximum patient comfort. Ultraleather Pro is ink and stain resistant, with antimicrobial disinfecting ingredients.

Volume 12 Number 1

S3100LC Endodontic Treatment Chair

• It also features a detachable foot control, lever-release drop-down arms, and a fixed toe with clear plastic protective cover.

Featured product: Endodontic Cart Like the S3100LC, this mobile operatory cart is prepared to perfectly fit into your endodontic practice. The Prestige Endodontic Cart is fitted with a lightweight aluminum body and all the features you need: aseptic surfaces for easy cleaning, sectioned drawers for intuitive organization, and a sleek, contemporary esthetic.

Endodontic Cart

Standard features: • A removable plastic top designed for easy cleaning, in addition to dual slideout surfaces for added work space.

• 5" easy-rolling wheels for smooth transit from patient to patient. Wheels lock for stability.

• Durable, scratch-resistant, nylon-reinforced polycarbonate bumper protects the cart’s wheels and exterior from wearand-tear over time.

• Auto-closing, ball-bearing drawers.

• Features four 3" drawers, one 6" drawer, and one 9" drawer.

The Boyd team has made every effort to create specialized products that are truly “Built for You.” These featured endodontic products can be combined with Boyd’s custom clinical and office cabinetry — with nearly limitless combinations of color and print laminates — to create a fully cohesive office space. Reach out to your regional sales representative today to get started!

To learn more, visit us at www.boyd industries.com, or stop by AAE 2019 Booth 1805 in May! You can also follow us on Instagram and Twitter @BoydIndustries.

Boyd Industries is an ISO 13485:2016 certified company. EP This information was provided by Boyd Industries.

Endodontic practice 55

SMALL TALK

Expect success Dr. Joel C. Small discusses how expectation of performance affects behavior

S

ome 50-plus years ago, noted psychologist and researcher Robert Rosenthal conducted a seminal research study on the self-fulfilling nature of teachers’ expectations for their students. Students in a California elementary school were administered IQ tests before the experiment. The teachers were unaware of any given student’s IQ score; however, they were given a list of students’ names who were considered potential “high achievers” based on their IQ scores. The list was actually a random sampling of students and had no correlation to any student’s performance on the IQ test.

At the end of the school year, the same IQ test was again administered, and the findings indicated that the students that teachers believed to be high achievers performed significantly better than other students based on their original IQ scores. Rosenthal’s conclusion was that a teacher’s expectation of performance has a significant influence on a student’s achievement. This phenomenon has become known as the Pygmalion Effect.

Rosenthal’s pivotal study sparked the interest of numerous subsequent researchers.

Although too numerous to mention, research studies have shown comparable results when the Pygmalion Effect is studied in areas such a parenting, leadership, and even the doctor’s effect on the success of treatment modalities for chronically ill patients.

With respect to our role as managers and leaders, can we not infer from these studies that our expectations of our staff would have a similar effect on their performance? In fact, this has been shown to be true. If we believe that our team members are capable, they will likely prove us right, thus becoming a

Like a drop of water in a pond that spreads out in concentric circles from its source, our belief in our team’s resourcefulness, creativity, and capability will have a ripple effect, resulting in improved productivity, staff satisfaction, and retention.

self-fulfilling prophecy. Like a drop of water in a pond that spreads out in concentric circles from its source, our belief in our team’s resourcefulness, creativity, and capability will have a ripple effect, resulting in improved productivity, staff satisfaction, and retention.

It is important that we take stock of our perceptions regarding team members.

Joel C. Small, DDS, MBA, ACC, FICD, is an endodontist, author, and board-certified executive leadership coach.

He received his MBA, with an emphasis in healthcare management, from Texas Tech University. He is a graduate of the University of Texas at Dallas postgraduate program in executive coaching and limits his coaching practice to motivated healthcare professionals. He is a nationally recognized speaker on the subjects of leadership and professional development. Dr. Small is available for speaking engagements and for coaching healthcare professionals who wish to experience personal and professional growth while taking their practices to a higher level of productivity. **To receive a free copy of Dr. Small’s “Core Values Exercise,” please contact the author at joel@joelsmall.com. He is also available for a complimentary coaching session to discuss your practice-related issues.

56 Endodontic practice

If we see our team members as incompetent, we should expect them to prove us right again — another self-fulfilling prophecy. We also must ask ourselves if they are truly incompetent; in which case, we should let them go. But what if we are the problem? What if we expect them to fail? What if we have not given them the resources, support, and confidence they need to not only to succeed, but also to thrive? Do we continue to suffer the consequences of our repeated self-fulfilling prophecies, or do we take inventory of our personal assumptions and change them accordingly? As is often the case, the choice is ours. *Those of us who are parents should heed this message as well. EP Volume 12 Number 1

Experiencing the power of digital communication.

ZEISS EXTARO 300

// INNOVATION MADE BY ZEISS

The integrated HD camera of the EXTARO® 300 from ZEISS records wirelessly to the ZEISS Connect App — empowering patient interaction and informed decisions with images and videos directly transferred to your local network.

• Benefit from a digital workflow • Easily educate your patients • Demonstrate the value of your work

Experience the ZEISS EXTARO 300 at the AAE Annual Meeting.

April 10-13, 2019 | ZEISS Booth 906

SUR.9424 ©2019 Carl Zeiss Meditec, Inc. All rights reserved.

DRIVING DIAGNOSTIC EXCELLENCE IS MORE THAN WHAT WE DO IT´S IN OUR DNA

2014: CS 8100 3D Carestream Dental

1960s: Dental X-ray Unit Trophy Radiologie

WORKFLOW INTEGRATION I HUMANIZED TECHNOLOGY I DIAGNOSTIC EXCELLENCE

Carestream Dental. Now 100% Digital.

Carestream Dental may be a new dental digital company, it has a long history of defining imaging and practice management technology. Strong legacy brands—which include Eastman Kodak, Trophy and PracticeWorks—have paved the way to bring dental workflows into the new realm of digitalization. And, as an independent company solely focused on the oral healthcare market, Carestream Dental will continue to drive innovation and deliver new solutions for practices.

From consultation to final treatment, we have the solution that’s right for you.

© 2019 Carestream Dental LLC. 18289 EN CS 8100 3D Family AD 0319 Trophy and PracticeWorks are trademarks of Carestream Dental Technology Topco Limited.

Kodak is a trademark of Eastman Kodak Company.

For more information, call 800.944.6365 or visit carestreamdental.com