Endodontic Practice US Fall 2019 Vol 12 No 3 by MedMark, LLC

clinical articles • management advice • practice profiles • technology reviews Fall 2019 – Vol 12 No 3 • endopracticeus.com

PROMOTING

EXCELLENCE

Negotiation of an S-shaped canal with an EDM-machined CM instrument: a case report Dr. Casper H. Jonker

Join the 80%: CBCT and endodontics Dr. Nestor Cohenca

A comparative study of the penetration time of different instruments and kinematics for reaching the apical limit during gutta-percha removal Drs. Gonzalo García, et al.

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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.

Education and technology continues to elevate interdisciplinary care

ith ever-advancing treatment modalities and technology, our path as clinicians and educators continues to evolve. Traditionally, for a healthcare profession that utilizes multiple specialists in conjunction with general care providers, a certain degree of communication breakdown is inherent to dentistry. While the discussion of treatment plans between providers is largely accomplished with the aid of study models, radiographs, and conversation, the ability to involve the patient and other clinicians in specific procedures has always been limited to postoperative descriptions. However, as new means of documenJon Irelan, DDS, MS, MS tation and communication arise, as clinicians we can educate patients and one another like never before. Advancements in 3D imaging allow us to approach endodontic issues with greater certainty, allowing us to more fully understand why an issue has arisen, and why it is presenting as such. This advantage, in addition to the ability to discuss these images with patients in real time using computers stationed in the operatory, furthers our capability to educate the patients about their unique clinical situation. This is vital for not only obtaining a truer informed consent from the patient, but also furthering the principals of patient autonomy and joint decision-making. Just as effective a tool for educating patients and our colleagues as 3D imaging, advances in microscopy have continued to revolutionize our clinical practice. While few endodontists could argue that the advent of microscopy has vastly improved our diagnostic, surgical, and orthograde treatment abilities, it is now shaping the way we communicate with one another. Important documentation of clinical findings was made possible by mounting SLR cameras using a beamsplitter and camera adapter, allowing for intraoperative information to be collected. Clinicians now had an opportunity to refer to additional image data during correspondence with colleagues. However, in addition to a decrease in available light source for the operator, organizing and viewing of images made in real time was not ideal using this technology. We now have microscopes such as the ZEISS EXTARO 300, which offers the opportunity to display photographs and live video feed wirelessly to an iPad®. With this technology, patients can readily see important visual information in real time, whether it is a crack or some other significant finding. Besides aiding our ability to better educate our patients, it allows for efficient decision-making with the patient mid-appointment if a prognostic concern arises. Also improved is the ability to communicate quickly with referring colleagues, as this feature allows for snapshots to be emailed directly from the application. The end result of an improved means of communicating with patients and our fellow colleagues is the greater ability to educate others on the treatment possibilities that endodontic procedures offer. By improving our ability to evaluate the clinical situation surrounding a tooth before, during, and after potential treatment, clinicians can better predict the prognosis. This means an improved understanding of when endodontic treatment is indicated and appropriate, and what potential complications might arise during and after treatment. By refining our ability for case selection and documentation, we also improve our ability to educate our colleagues and patients on the viability of modern endodontic orthograde treatments and microsurgery. Dr. Jon Irelan Jon Irelan, DDS, MS, MS, received his BS and DDS at Marquette University in Milwaukee, Wisconsin, as well as an MS in Prosthodontics and an MS in Endodontics from Marquette University. He continues as an Adjunct Assistant Professor of Endodontics at his alma mater. Dr. Irelan lectures nationally and internationally on topics including complex treatment planning and advanced restorative procedures, as well as maintaining a private practice in Mount Pleasant, Wisconsin.

ISSN number 2372-6245

Volume 12 Number 3

Endodontic practice 1

INTRODUCTION

Fall 2019 - Volume 12 Number 3

TABLE OF CONTENTS

Practice profile Band of brothers

Publisher’s perspective Turn your dreams into reality Lisa Moler, Founder/CEO, MedMark Media................................................ 6

Jeremy Young, DDS, MMSc; Mark Young, DDS, MMSc; Eric Young, DDS, MMSc; and Scott Young, DDS, MMSc

Continuing education Nonsurgical endodontic treatment of a maxillary central incisor diagnosed with infected dens invaginatus (Oehlers’ Type III) and apical periodontitis

Clinical research

2 Endodontic practice

Drs. Jorge Vieyra and Fabian Acosta present a case report that describes the diagnosis and conservative treatment of a unilateral case of a maxillary central incisor with an infected Type III dens invaginatus and an associated periradicular lesion ....................................................... 20

ON THE COVER Cover X-ray image courtesy of Drs. Gonzalo García, Denise Alfie, Pablo Alejandro Rodríguez, and Fernando Goldberg. See article on page 14.

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TABLE OF CONTENTS Technology Join the 80%: CBCT and endodontics Dr. Nestor Cohenca discusses the benefits of using 3D imaging in his endodontic practice.........................30

Research Influence of different irrigation solutions in the adhesive resistance of glass fiber posts on bovine radicular dentin Drs. Tiago André Fontoura de Melo and Daniel Galafassi, along with Cláudia Wagner, Bruna Machado dos Passos, and Priscila Souza de Souza, analyze the influence of an intracanal irrigating solution............................. 32

Product profiles What’s new in my sponge? Dr. Brett E. Gilbert discusses his experience with the Traverse™ glide path file system...............................40

Avalon Biomed Industry-leading bioceramics focused on serving endodontists and saving teeth................................................42

Continuing education

Negotiation of an S-shaped canal with an EDM-machined CM instrument: a case report

Dr. Casper H. Jonker reports on a patient with challenging canal anatomy

Practice development Small talk Five ways to improve endodontic practice efficiency

Weathering the storms of leadership

Dr. Roger P. Levin offers some tips to reduce stress and increase profitability. ....................................................... 44

Drs. Joel C. Small and Edwin McDonald discuss how a seasoned leader can create a balance .......................................................46

Product profile The importance of ultrasonic irrigation in modern endodontics Dr. Freddy Belliard discusses the use of Vista Dental’s products in developing a predictable irrigation regimen...........................................45

Book review Microsurgical Endodontics Augmented reality in microsurgical endodontics: the future of endodontic treatment .......................................................48

www.endopracticeus.com READ the latest industry news and business WATCH DocTalk Dental video interviews with KOLs LEARN through live and archived webinars RECEIVE news and event updates in your inbox by registering for our eNewsletter

CONNECT with us on social media Connect. Be Seen. Grow. Succeed. | www.medmarkmedia.com

4 Endodontic practice

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PUBLISHER’S PERSPECTIVE

Turn your dreams into reality

ecently, I had the exciting experience of interviewing Shaquille O’Neal for our publications. Shaq’s sleep (and health) have been impacted over the years by his sleep apnea, and our discussion primarily focused on his journey to finding a solution. Fortunately, we also had time to delve into his philosophy of life, his path to fulfillment, and future goals. Two of his basic tenets of life resonated with me, so much so that I wanted to share them with you in this issue’s message. First, Shaq noted that one of his favorite quotes is from Dwight D. Eisenhower, a former U.S. president and five-star general: “The greatest leaders are the ones smart enough to hire people smarter than them.” How true. While you bring the clinical knowledge to the practice, surrounding yourself with the Lisa Moler Founder/Publisher, MedMark Media best and the brightest opens up your world to ideas, insights, and talents beyond your own in other important areas. Thankfully, we have done that with the team at MedMark Media, and recommend that our readers should also take advantage of all of the experienced people who can expand your practice’s management, clerical, social media, and even clinical options in this very competitive specialty. Second, Shaq developed his life’s mission from another concept that he learned from his mother. He had given her some material gifts, to which she responded, “‘I don’t want these, Baby; I love you very much. What have you done to brighten up someone else’s day?” This reinforced what we try to practice every day. We know that taking care of business is our daily focus, but we also need to focus on taking care of others — and what better way than changing lives through our life’s calling! For me, it is improving dentists’ and patients’ health through bringing to light the important concepts and breakthroughs of our profession through our authors and advisors. You can expand patient care possibilities through CEs, our articles, webinars, DocTalk Dental videos, or any of the many educational options available in this quickly changing dental industry. While you’re at it, let your patients know how your practice is capable of changing or improving their lives! Use your social media, smartphones, and websites to spread the word. We’d like to spread the word about a few articles in our Fall issue of Endodontic Practice US. Dr. Casper Jonker’s article on negotiation of an S-shaped canal with an EDM-machined instrument addresses the challenges that the management of curved canals bring even for the most seasoned clinician. Drs. Jorge Vieyra and Fabian Acosta illustrate their technique for treating a tooth infected with dens invaginatus and apical periodontitis. After reading these articles, subscribers who pass the quizzes can obtain 4 CE credits! A comparative study by Drs. García, Alfie, Rodrqíuez, and Goldberg compared the time required by three different endodontic file systems with three different types of kinematics to penetrate the gutta percha until reaching the apical limit. And, our Practice Profile shines a spotlight on a band of four Young brothers who are realizing their dream of partnership in practice. While my interview with Shaq mainly focused on his nighttime sleep, we ended up discussing how to make every day count — a topic which always is our goal for all of you and your teams. To your best success! Lisa Moler Founder/Publisher MedMark Media

Published by

PUBLISHER Lisa Moler lmoler@medmarkmedia.com MANAGING EDITOR Mali Schantz-Feld, MA mali@medmarkmedia.com | Tel: (727) 515-5118 ASSISTANT EDITOR Elizabeth Romanek betty@medmarkmedia.com VP, SALES & BUSINESS DEVELOPMENT Mark Finkelstein mark@medmarkmedia.com NATIONAL ACCOUNT MANAGER Celeste Scarfi-Tellez celeste@medmarkmedia.com CLIENT SERVICES/SALES SUPPORT Adrienne Good agood@medmarkmedia.com CREATIVE DIRECTOR/PRODUCTION MANAGER Amanda Culver amanda@medmarkmedia.com MARKETING STRATEGIST Matt Simpson emedia@medmarkmedia.com SOCIAL MEDIA & PR MANAGER April Gutierrez medmarkmedia@medmarkmedia.com CONTENT MARKETING Lauren Nash emedia@medmarkmedia.com FRONT OFFICE ADMINISTRATOR Melissa Minnick melissa@medmarkmedia.com

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6 Endodontic practice

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PRACTICE PROFILE

Band of brothers Jeremy Young, DDS, MMSc; Mark Young, DDS, MMSc; Eric Young, DDS, MMSc; and Scott Young, DDS, MMSc What can you tell us about your background? We grew up just south of Sacramento in Elk Grove, California. We didn’t have much, and our parents really instilled in us the importance of hard work and doing a good job. We all had jobs, starting with a paper route for the Sacramento Bee, and then we each had various entry-level jobs throughout high school. Our parents made sure that we always gave our best effort in everything we did, and while they never expected perfection, they made it clear that we were capable of accomplishing anything we put our mind too. Our older brother, Jeremy, was a phenomenal basketball player but ended up hurting his back in high school, which pretty much ended his serious playing. He decided he wanted to coach basketball, and our mom encouraged him to be a dentist, so he could be his own boss and set his hours. One by one, each of four brothers ended up going into dentistry and then eventually into endodontics.

Dr. Scott Young’s Harvard graduation: Dr. Mark Young, Dr. Eric Young, program director Dr. Robert White and his wife, Dr. Scott Young, and Dr. Jeremy Young

When did you become specialists and why? Mark finished his residency in 2009 and Eric in 2015 after doing his residency in the U.S. Army. Scott completed his residency in 2018. All of us are very detail focused, and during dental school, we all explored the various specialties extensively. Treating patients in pain became a focus for each of us, and most of us explored oral and maxillofacial surgery (OMFS) as an option, but each ultimately decided we would rather save teeth than extract them.

Is your practice limited solely to endodontics, or do you practice other types of dentistry? Our practice is limited to endodontics, and it has kept us plenty busy.

Why did you decide to focus on endodontics? We have focused on endodontics as a specialty where our capability in diagnosis and technical skills is put to the test every day. 8 Endodontic practice

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PRACTICE PROFILE Do your patients come through referrals? About 95% of our patients come from the referral of general dentists. The remaining patients come from word-of-mouth referrals from family and friends of previous patients. When we initially started, we had only one office with a few referring physicians. However, as we focused on differentiating our practice on quality, we now have five offices and almost 1,000 referring physicians.

How long have you been practicing endodontics, and what systems do you use? Mark started Creekside Endodontics in Folsom, California, in 2009. When Eric graduated, he partnered with Mark and opened a new location in Roseville, California, in 2015. They opened a practice in Sacramento in 2018 and Auburn in 2019. Jeremy started Young Endodontics in Grass Valley, California, in 2005 and will be merging with Creekside Endodontics in late 2019. We use the metric system for measurement of canal lengths in millimeters and other treatment-related measurements, but we also use the imperial system of units while discussing the area of the office in square feet or temperature in degrees Fahrenheit.

What training have you undertaken? We each completed our endodontic residency training at Harvard. While serving in the U.S. Army, Eric was trained in Advanced Trauma Life Support and became certified in dental forensics.

Who has inspired you? Our parents have been a great inspiration in always doing good work and also in

Operatory

putting their children first. They focused on our education and made every effort to help each of us have the greatest opportunity. They truly embodied the idea of servant leadership in the household every day for us growing up.

What is the most satisfying aspect of your practice? Taking patients out of pain is definitely the most satisfying part of our practice. Unfortunately, we spend too much time dealing with patients suffering because their previous RCT was substandard. That’s why we made quality the backbone of our practice. It’s great to be able to fix these problems, but it would be even better if we were able to

treat them properly in the first place. We try to take time with all our patients to educate them on how to better assess the quality of their own dental care. We believe if patients take a more active and more educated role in their dental care, they can avoid a lot of pain and suffering in the first place.

Professionally, what are you most proud of? We take a great deal of pride in the quality of work that we do, not just because we’re passionate about doing good dental work, but because we take enormous pride in being able to help restore patients to peace and health. Going that extra mile, doing quality work that the patient may

Interior of Creekside Endodontics 10 Endodontic practice

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PRACTICE PROFILE never appreciate means we not only can help relieve their suffering today, but also do good quality that will last them a lifetime, not just until their next visit.

What do you think is unique about your practice? From the beginning, we agreed that we wanted to differentiate our practice on quality and transparency. We made sure to go that extra mile to do great clinical work, even if the patient couldn’t perceive the difference. We wanted to take pride in our work. Transparency also meant taking extra time to talk with patients and educate them on their teeth, the work being done, and how they can also assess good quality. For us, an educated patient who takes an active interest in his/ her dental care is the best patient. And we work hard to serve all patients well. Sometimes focusing on quality and being transparent has meant telling a patient we can’t help him/her and recommending extraction. While this isn’t financially good for us in the short term, we feel that it builds more trust and has helped us grow our business in the long term. By far, the most unique thing is that all four of us brothers are partners. It was always a dream of ours to practice together, and by the end of 2019, we will finally all be practicing under the Creekside Endodontics banner. A lot of people say working with family is trouble, but we get along great and have learned how to work together to

solve difficult problems. We have had to make some hard decisions along the way, but we have always put our relationship as brothers ahead of any selfish interest. When we stop thinking about ourselves primarily, we can focus on what is good for the business at large. Happily, most of the time what is best for the business is also good for the individuals in the practice.

What has been your biggest challenge? Starting Creekside Endodontics was a huge challenge. It took a long time to figure out how to grow from nothing into a thriving practice. Another challenge we faced as we started to grow past two offices was establishing systems to manage a large practice with multiple locations while still maintaining quality and transparency. A lot of the systems used to run a single office don’t scale when managing multiple practices. And it’s easy to lose quality as you add more staff and new systems. That’s why we’re so hands-on with our teams and make sure to review cases and touch base with our doctors.

What would you have been if you didn’t become dentists?

While each of us loves our chosen profession, each of us may have taken a separate path if events had unfolded differently. Eric would have pursued a career as an officer in the U.S. Army. Mark would likely be the CEO of a corporation, and Scott would

be saving lives as a firefighter after a stint in the U.S. Navy.

What is the future of endodontics and dentistry? The future of endodontics and dentistry is transparency. The proliferation of digital records in the era of social media and online resources have created an environment where patients seek information and guidance with ever greater degrees of sophistication. Patients are also facing expanding choices in dental care and can be even more mobile as digital records are easily shared. As clinicians, we will be pressed to deliver excellence in every patient encounter. If we offer quality and transparency with each interaction, patients can share that experience easily, and our business and profession will grow. However, the reverse is also possible; if we fail to offer quality and transparency, patients will demand change either by seeing a new dentist or by broader industry changes.

What are your top tips for maintaining a successful specialty practice? Maintaining high standards for both clinician and staff is one critical step in a successful practice. Small compromises add up over time and can gradually erode the foundation of the practice. When you and your staff know that quality is important, that it will be monitored and rewarded, they will deliver and continue to excel over time.

What advice would you give to a budding endodontist? Remain humble, and do your best every day. As trite as it sounds, it’s easy to fall into the routine and monotony of daily practice. It’s easy to look at patients as “customers” or numbers, but each one is an individual deserving of your best. Remember how fortunate we are to be in this profession. We are honored that patients come to us and trust us in their hour of need. We have a duty to treat each patient to the best of our ability.

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

The lobby of Creekside Endodontics 12 Endodontic practice

Eric enjoys serving as the family BBQ pitmaster when out of the office. Mark may be found chasing five small children around the house. And finally, Scott has become a novice carpenter engaged in myriad home improvement projects. EP Volume 12 Number 3

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CLINICAL RESEARCH

A comparative study of the penetration time of different instruments and kinematics for reaching the apical limit during gutta-percha removal in endodontic retreatment Drs. Gonzalo García, Denise Alfie, Pablo Alejandro Rodríguez, and Fernando Goldberg evaluate the time required by three endodontic file systems with three different types of kinematics to penetrate the gutta percha in endodontic retreatment Abstract Introduction This study aims to compare the time required by ProTaper Next™ (PTN; Dentsply Sirona, Ballaigues, Switzerland) in clockwise rotation and WaveOne® Gold (WOG; Dentsply Sirona) and RECIPROC® Blue (RcPB; VDW, Munich, Germany) in either reciprocating motion or counterclockwise rotation to penetrate the gutta percha until reaching the apical limit in endodontic retreatment. Materials and methods Fifty extracted human upper canines were instrumented manually up to a No. 40 K-file (Dentsply Sirona) and filled using the lateral compaction technique and AH Plus® (Dentsply DeTrey, Konstanz, Germany). The samples were divided into five groups of 10 teeth each (n = 10), according to the instrument and kinematics utilized: PTN X3 in continuous rotation; WOG medium with reciprocating motion; WOG medium with counterclockwise rotation; RcPB R40 with reciprocating motion; and RcPB R40 with counterclockwise rotation. The time to reach the working length (WL) was recorded and statistically analyzed. For statistical evaluation, an analysis of variance was performed by complementing it with orthogonal contrasts. The degrees of freedom were adjusted to calculate the contrasts because no homogeneity of variance was observed. SPSS 15.0 software was used for analysis. Gonzalo García, DDS, Denise Alfie, DDS, PhD, Pablo Alejandro Rodríguez, DDS, PhD, and Fernando Goldberg, DDS, PhD, are from the Department of Endodontics, School of Dentistry of the University of Buenos Aires, Argentina. Disclosure: The authors deny any conflicts of interest related to this study.

14 Endodontic practice

Results PTN instruments in clockwise rotation and WOG and RcPB in counterclockwise rotation required a significantly shorter time in seconds than WOG and RcPB in reciprocating motion to penetrate the gutta percha up to the WL (F4,45; P < 0,001). During the procedure, two WOG and one RcPB instruments in reciprocating motion fractured. Conclusion PTN instruments in clockwise rotation and WOG and RcPB in counterclockwise rotation are valid alternatives to penetrate the gutta percha in endodontic retreatment. Significance This study evaluated the time required by three endodontic file systems with three different types of kinematics to penetrate the gutta percha in endodontic retreatment. PTN in clockwise rotation and WOG and RcPB in counterclockwise rotation yielded the shortest penetration time.

Introduction Endodontic treatment failure may result from the presence of bacterial remnants that are not completely eliminated with instrumentation and irrigation procedures — obturation that is insufficient or from bacteria, which may have penetrated through deficient restorations in well-treated teeth.1-3 In this situation, the efficient removal of the filling material is necessary to assist with reinstrumentation, disinfection, and refilling of the root canal system up to the apical foramen.4 Currently, a large number of referrals include the need for endodontic retreatment or conventional orthograde retreatment.5-6 In these circumstances, once the coronal-radicular restoration is eliminated,

Figure 1: Radiographic images in buccal-lingual and proximal-proximal directions showing the homogeneity of the endodontic obturation

the gutta percha of the first endodontic treatment should be removed. The required procedures depend on the homogeneity of the filling material and length of the filled canal. Various procedures have been employed for this purpose — namely, heat, gutta-percha solvents, manual files, Gates-Glidden burs, ultrasound, and instruments specially designed for this purpose.7 When the filling is radiographically poor, Hedströem files are indicated to remove the gutta percha. In the case of retreatment due to persistent coronal leakage, the obturation material needs to be removed, which in most cases is well compacted and reaches the entire root canal from the cervical area to the apical foramen. In this situation, mechanical preparation favors gutta-percha removal, rapidly reaching the apical limit of the obturation.7 For this purpose, different special instruments Volume 12 Number 3

CLINICAL RESEARCH are marketed for gutta-percha removal, which include GPX™ (Brasseler, Savannah, Georgia); ProTaper® Universal Retreatment (Dentsply Sirona); R-ENDO (Micro-Mega, Besançon, France); and XP-endo® Finisher R (FKG Dentaire SA, La Chaux-de-Fonds, Switzerland). Generally, these instruments act in a clockwise rotational direction and are used at a higher rotation speed than those used for endodontic preparation. The heat generated by the faster rotational speed aids in softening the gutta-percha component of the obturation material, making removal easier. Currently, rotary and reciprocating instruments are used for root canal instrumentation. Within both systems, ProTaper Next (PTN) (Dentsply Sirona), used in continuous clockwise rotation, and WaveOne Gold (WOG) (Dentsply Sirona) and RECIPROC Blue (RcPB) (VDW, Munich, Germany), used in reciprocating motion, are found. PTN is an M-Wire NiTi instrument with a rectangular cross section and semi-active tip operated in continuous clockwise rotation. It is supplied in five sizes and tapers: X1 (#17.04), X2 (#25.06), X3 (#30.07), X4 (#40.06), and X5 (#50.06). WOG is a file with a parallelogram cross section with a semi-active tip. The files are marketed in four sizes — namely, small (#20.07), primary (#25.07), medium (#35.06), and large (#45.05) — and are used as the instrumentation for the root canal walls in a reciprocating motion. RcPB is also a NiTi instrument with reciprocating motion and an S-shaped cross section. It is supplied in three sizes and tapers: R25 (#25.08), R40 (#40.06), and R50 (#50.05). Both NiTi instruments are subjected to thermal treatments, providing greater flexibility and resistance to cyclic fatigue. This study offers a new alternative in the use of reciprocating instruments for the removal of gutta percha through a counterclockwise rotational movement. The aim of the present study is to compare the time required by PTN, WOG, and RcPB, to penetrate the gutta percha and reach the apical limit in retreatment procedures with different instruments and kinematics.

Materials and methods Fifty extracted upper human canines with a similar root length, completely formed apices, and no signs of root resorption were selected for this study. The tooth crowns were sectioned at 21 mm to obtain a standardized length. After access cavity 16 Endodontic practice

preparation, apical patency was confirmed with a size 15 K-file (Dentsply Sirona). The cervical and middle thirds were enlarged with sizes 1, 2, and 3 Gates Glidden (Dentsply Sirona). The root canal was manually instrumented using a step-back technique up to a 40 K-file (Dentsply Sirona) master apical size. Copious irrigation with sodium hypochlorite 2,5% was used during the shaping. The root canal system was dried with paper points (Meta Dental Co. Ltd, Republic of Korea) and obturated to the working length (WL) using a lateral compaction technique and AH Plus (Dentsply DeTrey, Konstanz, Germany). Next, radiographs of the specimens were obtained in the ortho-radial (buccallingual) and proximal-proximal directions to evaluate filling homogeneity (Figure 1). Accesses were sealed with Cavit™ (3M ESPE, Germany), and samples were stored in 100% humidity at 37º C for 10 days to allow the sealer to set. The samples were randomly divided into five groups of 10 teeth. • Group 1: Obturation removal with a PTN X3 file at a speed of 700 rpm and a torque of 4 Ncm (Figure 2). • Group 2: Obturation removal with WOG medium in reciprocating motion according to the program established by the endodontic motor (Figure 3). • Group 3: Obturation removal with WOG medium in continuous counterclockwise rotation at a speed of 700 rpm and a torque preset by the endodontic motor. • Group 4: Obturation removal with RcPB R40 in reciprocating motion according to the program established by the endodontic motor (Figure 4).

• Group 5: Obturation removal with RcPB R40 in continuous counterclockwise rotation at a speed of 700 rpm and torque preset by the endodontic motor. The Cavit coronal temporary restoration was removed, and for obturation removal, all instruments were used in a single crowndown movement until they reached the WL. Each instrument was discarded after being used in three root canals. The motor used was the X Smart® Plus (Dentsply Sirona), and all the samples were treated by the same operator. The penetration time of the instrument up to the WL was recorded with a Tressa (LAT-CRON, China) digital timer, and the values obtained were entered into an Excel spreadsheet prepared for that purpose. For the statistical evaluation, an analysis of variance was performed by complementing it with orthogonal contrasts to analyze the differences listed below. 1. Reciprocating motion versus clockwise or counterclockwise motion. 2. Clockwise motion versus counterclockwise motion. 3. Counterclockwise motion with RcPB versus counterclockwise motion with WOG. 4. Reciprocating motion with RcPB versus reciprocating motion with WOG. The degrees of freedom were adjusted to calculate the contrasts because no homogeneity of variance was observed. SPSS 15.0 software (SPSS Inc. 233 South Wacker Drive, Chicago, Illinois) was used for analysis.

Results The average time recorded in seconds required by the different instruments to

Figure 2: ProTaper NEXT X3 instrument

Figure 3: WaveOne Gold Medium instrument

Figure 4: RECIPROC Blue R40 instrument Volume 12 Number 3

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CLINICAL RESEARCH penetrate the gutta percha up to the WL is summarized in Table 1. According to the analysis of variance complemented with orthogonal contrasts, the instruments used in continuous clockwise and counterclockwise rotation required a significantly shorter time in seconds to penetrate the gutta percha up to the WL (F4,45; P < 0.001). During the procedure, two WOG and one RcPB instruments in reciprocating motion fractured. These teeth were discarded and replaced with new ones. The analysis of variance showed a significant effect of the evaluated variable (reciprocating motion versus clockwise or counterclockwise motion) (P < 0.001).

Discussion Many studies have reported that nickeltitanium instruments in either rotary or reciprocating motion are suitable for gutta-percha removal from the root canal in retreatment procedures.8-22,25-28 When the filling material is sufficiently compacted, access to the interior of the root canal is more complex. In this case, the procedure has mainly been performed with Gates Glidden burs and manual instruments, with or without solvents as adjuvants.7-9,11,13,20,21,24,26-28 Currently, the use of rotary or reciprocating mechanical instrumentation facilitates and speeds up this operative procedure.8-22,25-28 It is important to note that the published findings on the efficiency of the different engine-driven instruments are diverse and controversial. In an ex vivo study, Ma, et al.,13 observed that the use of solvents allowed the rotary instruments to reach the WL faster; however, in turn, they prevented the complete removal of the first filling material, as the chloroformsoftened gutta percha is distributed as a film on the surface of the root canal walls.22 This can hamper intimate contact with the subsequent re-obturation of the canal system, leading to increased coronal leakage potential. Therefore, the use of solvents was avoided in the present study by penetrating the gutta percha up to the WL by mechanical motion. In the present study, the obturation to be removed was made using the lateral compaction technique because it is the most universally used technique.13,23 Ma, et al.,13 and Frajlich, et al.,24 emphasized that filling-material removal, using the techniques involving thermoplasticized gutta percha, is difficult because of the greater compaction and homogeneity of the gutta percha. 18 Endodontic practice

Table 1: Descriptive summary of instruments, kinematics, and recorded times in seconds Condition

Mean

PTN-clockwise

18.8

3.9

WOG-reciprocating

78.2

29.4

WOG-counterclockwise

20.7

3.6

RcPB-reciprocating

94.1

22.9

RcPB-counterclockwise

17.5

5.6

Multiple publications show that WaveOne, WOG, and/or RECIPROC instruments are useful for removing gutta percha in endodontic retreatment with reciprocating motion.14-18, 25 In the present study, WOG and RcPB were also used in continuous counterclockwise rotation, corresponding to the direction of the cutting edges. In general, when the practitioner decides on a rotary or reciprocating mechanical system, treatment is facilitated if all the endodontic procedures are performed with the same system. For this reason, these instruments were analyzed in continuous rotary and reciprocating motion to evaluate their speed in accessing root canals up to the WL in retreatment. Several authors have used mechanical instrumentation at the rotation speed indicated by the manufacturer of the instruments. For guttapercha removal, this speed does not allow for a sufficiently fast action of the instruments, so some authors increased the speed to 500 rpm or more.7,8,11,13,17,18,20 Thus, a speed of 700 rpm was used in this study, both for PTN in continuous clockwise rotation and for WOG and RcPB in a counterclockwise direction. In the X Smart Plus motor, the torque cannot be modified in counterclockwise rotation; thus, the torque used was that allowed by the motor. Likewise, PTN X3 (#30.07), WOG medium (#35.06), and RcPB R40 (#40.06) files were used because they have a size and taper compatible with the root canal previously prepared and filled, as is the case in retreatment. The time used to penetrate the gutta percha up to the WL reported in different publications differs significantly.8,13,20,26 In this study, the time required to penetrate the gutta percha up to the WL with the instruments in continuous clockwise and counterclockwise rotation was shorter than what has been reported by other authors.8,13,20,26 By changing the reciprocating motion of

the WOG and RcPB instruments to continuous counterclockwise rotation, the speed of gutta-percha penetration significantly increased. Contact of the cutting edges of the instruments with the gutta percha in the appropriate rotary movement favors penetration. In this sense, we agree with Azim, et al.,19 that continuous rotation is the appropriate motion. Our results agree with those of Azim, et al.,19 who found that the use of WOG in reciprocating motion increases the time of gutta-percha removal. Therefore, in the present study, this instrument was also used in continuous counterclockwise rotation, making it easier to penetrate the mass of obturation material. Duncan and Chong7 considered that fracture of the instrument used for filling material removal is one of the most common risks during retreatment. In this study, two WOG and one RcPB fractured when used in reciprocating motion. We thought these fractures were caused by the greater pressure exerted for instrument progression into the gutta percha. Several publications note the fracture of different types of instruments during gutta-percha removal procedures in retreatment.8,9,19,26-28 However, no blockages or perforations were detected in the present study, perhaps because the evaluated roots had single and straight root canals.

Conclusion According to the findings, we conclude that the time required to penetrate the gutta percha up to the WL was shorter with the PTN instruments in clockwise rotation as well as WOG and RcPB in counterclockwise rotation compared with WOG and RcPB in reciprocating motion.

Acknowledgments The authors express their sincere appreciation to Professor Ricardo L. Macchi for his help with the statistical analysis. EP

REFERENCES 1. Siqueira JF Jr. Endodontic infections: concepts, paradigms, and perspectives. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2002;94(3):281-293. 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, RĂ´Ă§as IN. Clinical implications and microbiology of bacterial persistence after treatment procedures. J Endod. 2008:34(11):1291-1301. 4. Mandel E, Friedman S. Endodontic retreatment: a rational approach to root canal reinstrumentation. J Endod. 1992;18(11):565-569. 5. Abbott PV. Analysis of a referral-based endodontic practice: Part 2. Treatment provided. J Endod. 1994;20(5):253-257.

Volume 12 Number 3

7. Duncan HF, Chong BS. Removal of root filling materials. Endod Topics. 2011;19(1):33-57. 8. Betti LV, Bramante CM. Quantec SC rotary instruments versus hand files for gutta-percha removal in root canal retreatment. Int Endod J. 2001;34(7):514-519. 9. 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):469-742. 10. Saad AY, Al-Hadlaq SM, Al-Katheeri NH. Efficacy of two rotary NiTi instruments in gutta-percha removal during root canal retreatment. J Endod. 2007;33(1):38-41. 11. Somma F, Cammarota G, Plotino G, Grande NM, Pameijer CH. The effectiveness of manual and mechanical instrumentation for the retreatment of three different root canal filling materials. J Endod. 2008;34(4):466-469. 12. Marques da Silva B, Baratto-Filho F, Leonardi DP, et al. Effectiveness of ProTaper, D-RaCe, Mtwo, retreatment files with and without supplementary instruments in the removal of root canal filling material. Int Endod J. 2012;45(10):927-932. 13. Ma J, Al-Ashaw AJ, Shen Y, et al. Efficacy of ProTaper Universal Rotary Retreatment system for gutta-percha removal from oval root canals: a micro-computed tomography study. J Endod. 2012;38(11):1516-1520.

CLINICAL RESEARCH

6. Scavo R, Di Pietro S, Martínez Lalis R, Grana D. Incidence and distribution of endodontic treatments in a specialized clinic. Rev Asoc Odontol Argent. 2008;96(3):231-234.

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14. Zuolo AS, Mello JE Jr, Cunha RS, Zuolo ML, Bueno CE. Efficacy of reciprocating and rotary techniques for removing filling material during root canal retreatment. Int Endod J. 2013;46(10):947-953. 15. Ríos Mde A, 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. 16. Koçak M1, Koçak S, Türker SA, Sağlam BC. Cleaning efficacy of reciprocal and rotary systems in the removal of root canal filling material. J Conserv Dent. 2016;19(2):184-188. 17. Nevares G, de Albunquerque DS, Freire LG, et al. Efficacy of ProTaper Next compared with Reciproc in removing obturation material from severely curved canals: a micro-computed tomography study. J Endod. 2016;42(5):803-808. 18. Martins MP, Duarte MA, Cavenago BC, Kato AS, da Silveira Bueno CE. Effectiveness of 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(4):467-471. 19. Azim AA, Wang HH, Tarrosh M, Azim KA, Piasecki L. Comparison between single-file rotary systems: Part 1— Efficiency, effectiveness, and adverse effects in endodontic retreatment. J Endod. 2018;44(11):1720-1724. 20. 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. 21. Giuliani V, Cocchetti R, Pagavino G. Efficacy of ProTaper Universal retreatment files in removing filling materials during root canal retreatment. J Endod. 2008;34(11):1381-1384. 22. Sae-Lim V, Rajamanickam I, Lim BK, Lee HL. Effectiveness of ProFile .04 taper rotary instruments in endodontic retreatment. J Endod. 2000;26(2):100-104. 23. Savani GM, Sabbah W, Sedgley ChM, Whitten B. Current trends in endodontic treatment by general dental practitioners: report of a United States national survey. J Endod. 2014;40(5):618-624.

FINISHING FILES The Finishing File efficiently cleans canal walls and extracts residual debris from the canal, while simultaneously providing time and cost savings over sonic or ultrasonic instrumentation. AVAILABLE IN PACKS $ OF 6 FOR ONLY

24. Frajlich SR, Goldberg F, Massone EJ, Cantarini C, Artaza LP. Comparative study of retreatment of Thermafil and lateral condensation endodontic fillings. Int Endod J. 1998;31(5):354-357. 25. Scavo R, Gersuni C, Oliva S, Romero WS. Eficacia de dos sistemas mecanizados para la desobturación de conductos radiculares curvos obturados con GuttaCore [Efficacy of two engine-driven systems in the removal of GuttaCore fillings from curved root canals. Rev Asoc Odontol Argent. 2018;106(1):12-18. 26. Schirrmeister JF, Wrbas KT, Schneider FH, Altenburger MJ, Hellwig E. Effectiveness of a hand file and three nickeltitanium rotary instruments for removing gutta-percha in curved root canals during retreatment. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2006;101(4):542-547. 27. 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. 28. Unal GC, Kaya BU, Taç AG, Keçeci AD. A comparison of the efficacy of conventional and new retreatment instruments to remove gutta-percha in curved root canals: an ex vivo study. Int Endod J. 2009;42(4):344-350.

Volume 12 Number 3

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Endodontic practice 19

CONTINUING EDUCATION

Nonsurgical endodontic treatment of a maxillary central incisor diagnosed with infected dens invaginatus (Oehlers’ Type III) and apical periodontitis Drs. Jorge Vieyra and Fabian Acosta present a case report that describes the diagnosis and conservative treatment of a unilateral case of a maxillary central incisor with an infected Type III dens invaginatus and an associated periradicular lesion

ens invaginatus (DI) is a growth-related malformation resulting from invagination of the crown before calcification has developed (Hüllsmann, 1997). As the hard tissues are created, the invaginated enamel organ creates a small tooth inside the forthcoming pulp chamber. In the severe type of dens invaginatus, there is a folding of Hertwig’s epithelial sheath into the developing root (Bhaskar, 1986). The etiology of this dental malformation remains controversial, and although many hypotheses have been proposed, none has been supported or widely accepted. Numerous issues have been suggested to explain this uncommon dental formation, including trauma, infection, inhibition of the growth of specific cells, disruption of factors that regulate the formation of the enamel organ, and links to genetic factors (Hüllsmann, 1997; Alani and Bishop, 2008; Hosey and Bedi, 1996). Salter described a radiographic image that seems to be “a tooth within tooth” (Salter, 1855). DI can be cataloged according to its complexity, with the welldocumented classification of Oehlers (1957) describing three forms according to the complexity of the invagination into the root: Type I is limited to the crown, whereas Type II invagination extended inside the root, ending as a blind pod. Type III invagination invades the entire root and exit apically or laterally (Figure 1). Its occurrence varies from 0.3% to 10% (Hovland and Block, 1977), with the upper lateral

Jorge Paredes Vieyra, DDS, MSc, PhD, is an endodontist and professor of endodontics and pulp therapy at the School of Dentistry, Universidad Autónoma de Baja California, Campus Tijuana, Tijuana, Baja California, Mexico. Fabian Ocampo Acosta, DDS, MSc, is a histopathologist and professor at Universidad Autónoma de Baja California, Campus Tijuana, Tijuana, Baja California, Mexico.

20 Endodontic practice

Educational aims and objectives

This article aims to present and discuss nonsurgical endodontic treatment of a maxillary central incisor diagnosed with infected dens invaginatus (Oehlers’ Type III) and associated apical periodontitis utilizing ultrasonic and hand instruments and the surgical operating microscope as an auxiliary tool for both diagnosis and treatment planning.

Expected outcomes

Endodontic Practice US subscribers can answer the CE questions on page 24 to earn 2 hours of CE from reading this article. Correctly answering the questions will demonstrate the reader can: •

Observe nonsurgical endodontic treatment of a maxillary central incisor diagnosed with infected dens invaginatus (Oehlers’ Type III) and associated apical periodontitis utilizing ultrasonic and hand instruments and the surgical operating microscope as an auxiliary tool for both diagnosis and treatment planning.

•

Identify some etiology of dens invaginatus (DI).

•

Identify some challenges of teeth with DI for root canal therapy because of their complex anatomy.

•

Recognize the importance of a meticulous radiographic inspection for identification of DI, and the benefits of CBCT imaging in the diagnosis of teeth with unusual anatomy.

•

Recognize the benefits of using an operating surgical microscope and ultrasonic instruments during these clinical procedures.

incisor the most frequently affected tooth followed by the upper central incisor. Teeth with DI pose a challenge for root canal therapy because of their complex anatomy. Numerous clinical procedures have been proposed such as nonsurgical root canal treatment (Hovland and Block, 1977), combined root canal and surgical treatment (Benenati, 1994), planned replantation (Lindner, et al., 1995), and extraction (Rotstein, et al., 1987). However, planned replantation and extraction are commonly the last decision. Outcome studies for the management of teeth with DI are, however, unavailable due to the rarity of the condition. The following clinical circumstance describes the successful nonsurgical RCT of a maxillary central incisor diagnosed with infected dens invaginatus (Oehlers’ Type III) and associated apical periodontitis utilizing ultrasonic and hand instruments. Surgical operating microscopes were used as an aid for diagnosis, and the planning of treatment is highlighted.

Figure 1: Classification of dens invaginatus. Adapted from Oehlers (1957) Type I (A); Type II (B, C); Type III (D)

Case report A 22-year-old male patient presented at the dental school in Tijuana, Mexico, with a history of pain and inflammation in the maxillary right anterior region. After initial examination, the patient was referred to the endodontic department for consultation and further management. The patient reported mild pain and swelling about a week before, but at the day of examination, there were no clinical manifestations. Volume 12 Number 3

Clinical inspection showed the maxillary right central incisor UR1 restored with a porcelain crown. There was no sign of sinus tract or swelling; nonetheless, the tooth was vaguely tender to tapping. The labial mucosa related to the maxillary right central incisor was sore. The porcelain crown was removed, and UR1 was non-responsive to cold stimulation (Endo-Ice®, Coltene), while the adjacent teeth responded normally. A periodontal examining was within standard limits (Figures 2A and 2B). Radiographic inspection showed immature root development, an apical radiolucency of about 4 mm in diameter, and an abnormal internal structure corresponding with Type III DI (Figure 3A). A diagnosis of pulp necrosis with apical periodontitis was made. The contralateral central incisor was also tested for clinical and radiographic signs of the same malformation, but there were none. The patient’s general dentist had suggested antibiotics (amoxicillin 250 mg, 3 times a day for 7 days) and an analgesic (ibuprofen 400 mg, 3 times a day for 7 days).

Treatment procedure A clinical strategy was developed that included nonsurgical root canal treatment (RCT) of the dens tract over some appointments, comprising the use of a calcium hydroxide dressing. The treatment plan presented to, and accepted by, the patient was to perform removal of the DI and the infected necrotic pulp tissue, followed by the complete RCT. Written consent was obtained before initiation of RCT and notably addressed all the available treatment options and their associated risks, benefits, and challenges. A surgical operating microscope (Carl Zeiss Surgical, Oberkochen, Germany) was used during the treatment. After anesthesia with 2% lidocaine, 1: 100,000 epinephrine (Xylocaine®, Dentsply Sirona), the crown was removed during diagnostic phase, and a rubber dam was placed and stabilized with dental dam cord (Wedjets®, Coltene). Access was prepared with a 331-carbide bur in the lingual side of the tooth. Entrance into the large pulp chamber of the invagination via an occlusal access revealed a serosanguinous discharge, which could drain. The infected pulp tissue was removed, and the irregular invaginated tissue was cautiously eliminated by chemomechanical preparation using ultrasonic endodontic tips sizes 2-4 (ProUltra® endo-coated instrument, Dentsply Sirona) at power setting 4 of the Volume 12 Number 3

Figures 2A and 2B: A. Labial view of maxillary right central incisor. B. Palatal aspect of UR1 with the developmental defect

ultrasonic unit (Satelec P5, Acteon UK) in a brushing movement starting from an apical to coronal direction. The root canal was prepared primarily with a long tapered diamond bur to improve access to the apical defect. Working length of the dens tract was estimated with an apex locator (Root ZX; J Morita Corp, Tustin, California) and was verified radiographically (Figure 3B). The root canal was initially debrided with large K-file instruments up to size 90. The master apical size of 130 was achieved using K-files (SybronEndo, Orange, California). The remaining root canal was molded as far as possible with Gates Glidden drills (Dentsply Maillefer) sizes 2-4. To maximize proper disinfection, irrigation was performed with 5.25% sodium hypochlorite (NaOCl) in the pulp chamber and 2.5% NaOCl in the apical part of the canal system with regard to incomplete apical closure of the root. Some 2 ml of 17% EDTA was used to remove the smear layer. The final irrigation of the canal with NaOCl was supported using the ultrasonic unit (Piezon Master 400; EMS, Optident UK). Sodium hypochlorite was delivered into the canal by using a syringe, and ultrasonic passive irrigation was performed for 1 minute. The root canal was desiccated with sterile absorbent paper cones size #100, and dressed with Ca(OH)2 paste (Pulpdent Corp, Watertown, Massachusetts). The entrance of the pulp chamber was temporarily sealed with Cavit™ (3M Oral Care) and Fuji IX (GC UK) to avoid infection of the root canal system. The porcelain crown was cleaned and replaced for esthetic reasons (Figure 3C). The patient returned after 2 weeks, having remained free of any symptoms. At this second appointment, the tooth was not sensitive to percussion, and the soft tissues

in the area were not tender to palpation. The tooth was anesthetized as earlier defined, and a rubber dam was placed. The invagination was opened and flooded with 1% NaOCl followed by a final rinse with 17% EDTA for 1 minute and passive ultrasonic irrigation (ProUltra tips 1 and 2; Dentsply Maillefer, Ballaigues, Switzerland) with 1% sodium hypochlorite for 1 minute after elimination of calcium hydroxide paste. After additional irrigation, the canal was desiccated with sterile absorbent paper cones, and further Ca(OH)2 was placed in the canal. The tooth was temporarily sealed with Cavit and Fuji IX as previously described. The patient was requested to return 3 weeks later for completion of nonsurgical RCT. At the third visit, the tooth was anesthetized as described before and isolated with a rubber dam. The tooth was accessed, and Ca(OH)2 was removed from the root canal with passive ultrasonic irrigation, and the canal was desiccated with sterile absorbent paper cones size #100. The prepared root canal was filled with a master apical gutta-percha cone size #110 (Figure 3D) and warm gutta percha using an Obtura gun (Obtura II, Fenton, Missouri) and AH26® sealer (DeTrey Dentsply, Konstanz, Germany). A bolus of thermoplasticized injectable gutta percha heated to 150 ºF, was delivered, carefully positioned around the master apical gutta percha with use of Schilder pluggers size No. 10 (Dentsply Maillefer, Ballaigues, Switzerland). Serial radiographs were exposed to visualize and check its acceptable adaptation and to confirm the absence of extrusion outside the apical foramen (Figure 3E). The rest of the root canal system was then filled with thermoplasticized gutta percha, warmed to 150 ºF. The access was sealed with a light-cured composite, and a postoperative radiograph Endodontic practice 21

CONTINUING EDUCATION

Diagnosis and treatment planning

CONTINUING EDUCATION was taken. The patient was advised to take 400 mg ibuprofen (every 6 hours as needed for pain); antibiotics were not deemed necessary because of the absence of signs/symptoms. The patient was then referred to his attending dentist, and he was asked to return in 48 hours and was seen at 1-month, 3-month, 6-month and 1-year recall periods (Figure 3F).

Discussion RCT of teeth with DI can be demanding because of the capricious form of the internal anatomy and the circumstance that the dens tract is covered with enamel (HĂźllsmann, 1997). Additionally, pulp necrosis in such teeth usually develops before complete apical closure, leaving the root canal with a wide apical opening. The clinical protocol includes an effective treatment plan based on the knowledge of signs, symptoms, and radiographs. A meticulous radiographic inspection plays a key role in the identification of DI. Nevertheless, standard or digital periapical radiographs may not show the features and size of the invagination (VierPelisser, et al., 2012). CBCT imaging has been shown to be useful in the diagnosis of teeth with unusual anatomy. The introduction of cone beam computed tomography (CBCT) brought about a revolution in dentistry that has contributed to the planning, diagnosis, therapy, and prognosis of several dental procedures (Kaneko, et al., 2011). Teeth with DI present physical defects that are predisposed to caries because of the deep pits, which act as locations of plaque retention. Microbes and their products may exacerbate infection and lead to necrosis of the pulp, frequently before final maturation of the root (Cengiz, 2006). Therefore, DI requires early diagnosis and treatment. A major condition for effective RCT is the whole elimination of irritants from the infected root canal system. A tooth with DI shows a diversity of canal morphologies such as concavities, intracanal communications, apical ramifications, and other regions that instruments cannot reach. The complicated structure in DI affects the prognosis of the tooth. The case of DI presented here exemplifies only one clinical handling approach, which may not necessarily be appropriate in all such clinical scenarios. The irregular dimensions of the root canal system make proper shaping and cleaning complicated. A large amount of dentin has to be removed to ensure adequate cleaning. Regrettably, this may end in increased 22 Endodontic practice

Figures 3A-3C: A. Initial radiograph of the UR1 with the dens invaginatus. B. A working length. C. Calcium hydroxide inside the canal

Figures 3D-3F: D. Fit a master apical gutta percha size #110. E. Radiographs were exposed to visualize and confirm its satisfactory adaptation and to verify the lack of extrusion beyond the apical foramen. F. A recall periapical radiograph taken 12 months after the initial appointment

fracture predisposition of the thin rootend walls. Elimination of the invaginated form of hard tissue in the root canal is tough and challenging. Thus, the clinician should select a suitable way to eliminate the hard tissue, the necrotic material, and the microorganisms. In this case, the use of an operating surgical microscope and ultrasonic instruments facilitated the clinical procedures. In some clinical situations, the abnormal structure of DI is internal and an independent unit from the rest of the tooth. In these occurrences, the complete elimination of the central-anomalous structure and total elimination of pulp tissue can be followed with this valuable clinical aid. An ideal endodontic repair material should seal the pathways of communication between the root canal and its neighboring tissues. It should be harmless, non-carcinogenic, biocompatible, insoluble in tissue fluids, and physically stable (Bogen and Kuttler, 2009). Calcium hydroxide as interappointment treatment, ultrasonic instrumentation, and passive irrigation are necessary and suggested (Bishop and Alani, 2008). Obturation techniques using thermoplasticized

injection of gutta percha are proper for such teeth because they allow flow of softened gutta percha into unreachable areas better than other techniques, but they have a risk of extrusion in teeth with an open apex (de Sousa and Bramante, 1998). Several methods have been proposed to strengthen the root (Katebzadeh, et al., 1998; Lertchirakarn, et al., 2002). Materials like MTA can be considered an option in RCT of immature permanent teeth with DI with the advantage of shorter treatment time, good sealing ability, and great biocompatibility (Kumar, et al., 2014). The procedural difficulty encountered is controlling the overfill or underfill of MTA. Most of these include bonding a material to the root dentin inside the root canals. However, it has been shown that such a bond can break down over time (Kitasako, 2002). Hence, long-term decrease of fracture exposure employing bonding techniques must be debatable. In the present-day case, the dentin wall seemed to be practically thick, so fracture was not a main concern (Brooks and Ribera, 2014; Narayana, et al., 2012; Zoya, et al., 2015; Zhang and Wei, 2017). Volume 12 Number 3

The present-day report shows the truthful diagnosis and conservative treatment of dens invaginatus using current endodontic methods. This case report demonstrates that Type III dens invaginatus can be treated nonsurgically with the aid of the dental operating microscope, and ultrasonic and hand endodontic instruments. EP REFERENCES 1. Alani A, Bishop K. Dens invaginatus: Part 1: classification, prevalence and aetiology. Int Endod J. 2008; 41(12):1123-36. 2. Benenati FW. Complex treatment of a maxillary lateral incisor with dens invaginatus and associated aberrant morphology. J Endod. 1994;20(4):180-182. 3. Bhaskar SN. Synopsis of Oral Pathology. J Oral Maxillofac Surg. 1986;44(11):929 4. Bishop K, Alani A. Dens invaginatus. Part 2: clinical, radiographic features and management options. Int Endod J. 2008;41(12):1137-1154. 5. Bogen G, Kuttler S. Mineral trioxide aggregate obturation: a review and case series. J Endod. 2009; 35(6):777-790. 6. Brooks JK, Ribera MJ. Successful nonsurgical endodontic outcome of a severely affected permanent maxillary canine with dens invaginatus Oehlers type 3. J Endod. 2014;40(10):1702-1707.

CONTINUING EDUCATION

Conclusions

7. Cengiz SB, Korasli D, Ziraman F, et al. Non-surgical root canal treatment of dens invaginatus: reports of three cases. Int Dent J. 2006;56(1):17-21.   8. de Sousa SM, Bramante CM. Dens invaginatus: treatment choices. Endod Dent Traumatol. 1998; 14(4):152-158. 9. Hosey MT, Bedi R. Multiple dens invaginatus in two brothers. Endod Dent Traumatol. 1996;12(1):44-47. 10. Hüllsmann M. Dens invaginatus: aetiology, classification, prevalence, diagnosis, and treatment considerations. Int Endod J. 1997;30(2):79-90. 11. Hovland EJ, Block RM. Nonrecognition and subsequent endodontic treatment of dens invaginatus. J Endod. 1977;3(9):360-362. 12. Lindner C, Messer HH, Tyas MJ. A complex treatment of dens invaginatus. Endod Dent Traumatol. 1995;11(3):153-155. 13. Kaneko T, Sakaue H, Okiji T, Suda H. Clinical management of dens invaginatus in a maxillary lateral incisor with the aid of cone-beam computed tomography—a case report. Dent Traumatol. 2011;27(6): 478-483.  14. Katebzadeh N, Dalton BC, Trope M. Strengthening immature teeth during and after apexification. J Endod. 1998;4(24):256-259.  15. Kitasako Y, Burrow MF, Nikaido T, Tagami J. Long-term tensile bond durability of two different 4-META containing resin cements to dentin. Dent Mater. 2002;18(3):276-280. 16. Kumar A, Yadav A, Shetty N. One-step apexification using platelet rich fibrin matrix and mineral trioxide aggregate apical barrier. Indian J Dent Res. 2014;25(6):809-812.   17. Lertchirakarn V, Timyam A, Messer HH. Effects of root canal sealers on vertical root fracture resistance of endodontically treated teeth. J Endod. 2002;28(3):217-219. 18. Narayana P, Hartwell Wallace R, Nair UP. Endodontic Clinical Management of a Dens Invaginatus Case by Using a Unique Treatment Approach: A Case Report. J Endod. 2012;38(8):1145-1148. 19. Oehlers FA. Dens invaginatus. I. Variations of the invagination process and associated anterior crown forms. Oral Surg Oral Med Oral Pathol. 1957;10(11):1204-2018. 20. Rotstein I, Stabholz A, Heling I, Friedman S. Clinical considerations in the treatment of dens invaginatus. Endod Dent Traumatol. 1987;3(5):249-254. 21. Salter S. Warty tooth. Trans Pathol Soc Lond. 1855;6:173-177. 22. Vier-Pelisser FV, Pelisser A, Recuero LC, et al. Use of cone beam computed tomography in the diagnosis, planning and follow up of a type III dens invaginatus case. Int Endod J. 2012;45(42):198-208. 23. Zhang P, Wei X. Combined Therapy for a Rare Case of Type III Dens Invaginatus in a Mandibular Central Incisor with a Periapical Lesion: A Case Report. J Endod. 2017;43(8):1378-1382. 24. Zoya A, Ali S, Alam S, et al. Double Dens Invaginatus with Multiple Canals in a Maxillary Central Incisor: Retreatment and Managing Complications. Int Endod J. 2015;11:1927-1932. 25. Vertucci FJ. Root canal anatomy. of the human permanent teeth. Oral Surg Oral Med Oral Pathol. 1984;58(5):589-599.

Volume 12 Number 3

Endodontic practice 23

REF: EP V12.3 VIEYRA/ACOSTA

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Nonsurgical endodontic treatment of a maxillary central incisor diagnosed with infected dens invaginatus (Oehlers’ Type III) and apical periodontitis VIEYRA/ACOSTA

1. Dens invaginatus (DI) is a growth-related malformation resulting from invagination of the crown ________. a. after calcification has developed b. before calcification has developed c. during calcification d. in the absence of calcification 2. (For the patient in this article) To maximize proper disinfection, irrigation was performed with ________ sodium hypochlorite (NaOCl) in the pulp chamber and 2.5% NaOCl in the apical part of the canal system with regard to incomplete apical closure of the root a. 1% b. 2.5% c. 4% d. 5.25% 3. (For this patient) Some 2 ml of ________ EDTA was used to remove the smear layer. a. 10% b. 15% c. 17% d. 20% 4. (For this patient) Sodium hypochlorite was delivered into the canal by using a syringe, and

24 Endodontic practice

ultrasonic passive irrigation was performed for ________. a. 1 minute b. 3 minutes c. 5 minutes d. 6 minutes 5. At this second appointment, _______. a. the tooth was not sensitive to percussion b. the soft tissues in the area were not tender to palpation c. the tooth was sensitive to percussion d. both a and b 6. (At this patient’s third visit) A bolus of thermoplasticized injectable gutta percha heated to _________, was delivered, carefully positioned around the master apical gutta percha with use of Schilder pluggers size No. 1. a. 75 ºF b. 100 ºF c. 150 ºF d. 212 ºF 7. The introduction of ________ brought about a revolution in dentistry that has contributed to the planning, diagnosis, therapy, and prognosis of several dental procedures.

a. b. c. d.

cone beam computed tomography (CBCT) curing lights gutta percha sodium hypochlorite

8. ________ of dentin has to be removed to ensure adequate cleaning a. A small amount b. A large amount c. A negligible amount d. None 9. An ideal endodontic repair material should seal the pathways of communication between the root canal and its neighboring tissues. It should be harmless, ________, and physically stable. a. non-carcinogenic b. biocompatible c. insoluble in tissue fluids d. all of the above 10. This case report demonstrates that Type III dens invaginatus can be treated nonsurgically with the aid of the ________. a. dental operating microscope b. ultrasonic instruments c. hand endodontic instruments d. all of the above

Volume 12 Number 3

CE CREDITS

ENDODONTIC PRACTICE CE

Dr. Casper H. Jonker reports on a patient with challenging canal anatomy Introduction During root canal treatment, the shaping sequence plays a vital role in the endodontic procedure and can ultimately determine the outcome. Historically, shaping of root canals was done with stainless steel files, but in the early 1980s, nickel titanium provided the revolutionary turn-around in the shaping procedure (Peters, 2004). The introduction of nickel titanium provided substantial benefits, which include protecting the original canal shape and reducing iatrogenic errors during cleaning and shaping (zipping, ledges, and perforations) (Topcuoğlu, et al., 2016). In modern times, numerous rotary file innovations have been introduced to the endodontic market, and rotary file systems differ in their designs from one system to the other. The different approaches in designs are an effort to eliminate procedural errors. However, the management of curved canals remains a huge challenge for any instrument even in the hands of the experienced clinician (Yared, 2008). Recently, an innovative endodontic instrument design has been introduced. It is manufactured using controlled-memory (CM) nickel-titanium wire and the Electric Discharge Machining (EDM) manufacturing process. Controlled memory can be defined as the process where the shape memory of the nickel-titanium alloy is removed by a special thermomechanical process (Shen, et al., 2013). The EDM procedure is a process where there is no contact between the work piece and manufacturing apparatus, and only a pulsating electric current removes parts of the alloy. The metal alloy is immersed in a dielectric medium, which allows electric discharge flow between an electrode and the metal alloy. Melting and evaporation of Casper H. Jonker, BChD Dip Odont Msc, is from the Module of Endodontics, Department of Operative Dentistry, School of Oral Health Sciences, Sefako Makgatho Health Sciences University, Gauteng, South Africa. Disclosure: The author has no conflict of interest, which may arise from any form of commercial association with the content of the manuscript.

Volume 12 Number 3

Educational aims and objectives

The aim of this article is to highlight the vital role of the shaping sequence in endodontic procedures.

Expected outcomes

Endodontic Practice US subscribers can answer the CE questions on page 29 to earn 2 hours of CE from reading this article. Correctly answering the questions will demonstrate the reader can: •

Recognize that the Hyflex EDM rotary file system can safely and efficiently negotiate challenging anatomy in spaces with limited access.

•

Review how the shaping sequence plays a vital role in the endodontic procedure.

•

Realize how canal anatomy can play a vital role in instrument fatigue and fracture.

•

Realize some unique characteristics of the EDM manufacturing process of controlled-memory (CM) nickeltitanium wire.

•

Realize the importance of creating a smooth glide path.

Figure 1: Preoperative radiograph revealing a large fragment of a fractured instrument in the mandibular second incisor

the alloy occur in a controlled and repeatable way (Coltene endo, 2016; Jameson, 2001). The end result is an extremely flexible endodontic file where areas of the surface are superficially removed leaving a surface with evenly distributed craters (Figure 1) (Guo, et al., 2013). The following case report presents a detailed approach on the use of the Hyflex EDM rotary endodontic system in the negotiation of a tooth with challenging anatomy.

Case report

Figure 2: Preoperative radiograph revealing challenging root canal morphology and an apical radiolucency on the apex of the mesial root

First visit A 26-year-old female patient was referred to the department of operative dentistry at Sefako Makgatho Health Sciences University for endodontic treatment on her upper right second molar. Emergency root canal treatment was performed on a previous visit. The patient presented with an uncomplicated medical history, and the patient reported no

further symptoms on the treated tooth after the initial visit. A preoperative radiograph revealed the upper right second molar with challenging anatomy, narrowing of the root canal spaces, and an apical radiolucency on the apex of the mesial root (Figure 2). The tooth was anesthetized, the temporary restoration was removed, and straight Endodontic practice 25

CONTINUING EDUCATION

Negotiation of an S-shaped canal with an EDM-machined CM instrument: a case report

CONTINUING EDUCATION line access was achieved. A rubber dam was placed, and the orifices of the mesio-buccal, distal, and palatal canals were located, but sclerotic tooth structure covered the pulp floor and location of a potential second mesio-buccal canal (MB2). Sclerotic tooth structure was carefully removed with a longshank slow round carbide bur (Komet Dental, Brasseler, Germany) (Figure 3) and ultrasonics (Start-X™ number 3, Dentsply Sirona Endodontics, USA Headquarters) (Figure 4) under magnification using the dental operating microscope (Carl Zeiss, Oberkochen, Germany), but no orifices were detected after careful investigation of the pulp floor map (Figure 5). The remaining canals were scouted and negotiated, and length determination was done using the electronic apex locator (ProPex® II, Dentsply Sirona Endodontics), a size 10 K-file (Dentsply Sirona Endodontics, USA Headquarters) and RC-Prep® (Premier® Dental, Plymouth Meeting, Pennsylvania) as lubrication. Length determination was confirmed with conventional radiographs and a double curve/S-curve was noted in the mesio-buccal canal (Figure 6). The orifices were enlarged with the HyFlex® EDM orifice opener (Coltene, Langenau, Germany; Cayahoga Falls, Ohio) (Figure 7). The instrument was used with RC-Prep as lubricant and gentle apical pressure to avoid binding to the root canal walls and a brushing motion away from the furcation region. The initial glide path was created to a loose size 10 K file with RC-Prep as lubricating agent in all canals. All canals were irrigated using 3.5% sodium hypochlorite, patency confirmed, recapitulated, and re-irrigated to remove debris and prevent dentinal mud. With sodium hypochlorite left in situ and following the manufacturer’s instructions to use the instrument in a brushing motion and gentle apical pressure on the outstroke, the Hyflex EDM glidepath file (Coltene, Langenau, Germany) (Figure 8) was used to complete glide path preparation on each canal to full working length. Before introduction to each canal, the file was inspected for unwinding under high magnification, but no visible signs of alteration were identified. All canals were irrigated in a similar method as described above and patency confirmed. After completion of glide path preparation, the Hyflex® EDM Onefile (Coltene, Langenau, Germany) (Figure 9) was used to prepare each canal to full working length, and sodium hypochlorite was left in situ as lubricating and disinfection agent. The controlled memory effect of the instrument allowed pre-curving 26 Endodontic practice

Figure 3: Long shank slow round carbide bur used under magnification for the removal of sclerotic tooth structure

Figure 4: Start-X number 3 ultrasonic tip used under magnification for the removal of sclerotic tooth structure

Figure 5: Removal of sclerotic tooth structure in an effort to locate MB2. No orifices were detected after investigation of the pulp floor map

Figure 6: Confirmation of the S-curved root canal configuration in the mesio-buccal root during the length confirmation radiograph with a size 10 K file

and access into all canals, especially the mesio-buccal canal (Figure 10). The file was used in a similar technique as described with the Hyflex EDM glidepath file. Canals were dried with large paper points and dressed with calcium hydroxide paste (Calasept® Plus, Nordiska Dental, Sweden) and the tooth temporized (Ketac™ Molar, 3M Oral Care). Postoperative instructions were provided after the preparation phase of the treatment, and the patient was re-scheduled for the final phase for filling.

all canals to confirm correct length. Canals were obturated using cold lateral condensation with Guttaflow® bioseal root canal sealer (Coltene, Langenau, Germany). The appropriate electric heated pluggers (40/03 plugger for mesial and distal canals, 60/06 plugger for the palatal canal) (Calamus® Dual, Dentsply Sirona Endodontics, USA Headquarters) were selected for gutta percha burn-off and removal of a small coronal portion of obturation material from each canal (Figure 11). Obturations were vertically compacted after burn-off using Machtou pluggers (Dentsply Sirona Endodontics, USA Headquarters). Heated gutta percha and vertical condensation with Machtou pluggers were used to fill the coronal void of root canal space (Calamus Dual, Dentsply Sirona Endodontics, USA Headquarters) (Figure 12 and 13). A temporary restoration was placed, and the patient was re-scheduled for the restorative phase.

Second visit The patient was seen 2 weeks after the previous visit and reported no discomfort since the last visit. The temporary restoration was removed and rubber dam isolation achieved. All canals were irrigated with 3.5 sodium hypochlorite and dried with large paper points. As a final rinse, 17% EDTA solution (SmearClear™, Kerr Dental, Orange, California) was left in situ for 1 minute to remove the smear layer and dried with large paper points. The Hyflex EDM OneFile guttapercha cones were fitted and measured in

Discussion According to literature, it is well documented that the extent of curvatures in the Volume 12 Number 3

Volume 12 Number 3

Figure 7: The Hyflex EDM Orifice Opener used in a brushing motion and gentle apical pressure to enlarge the root canal orifices

Figure 8: The Hyflex EDM Glidepath file used in a brushing motion to complete the glide path preparation to full working length

Figure 9: The Hyflex EDM Onefile used in a brushing motion to complete shaping of all root canals to full working length

Figure 10: The controlled memory effect allowing pre-curving and access of the Hyflex EDM Onefile in canals difficult to access

It must also be emphasized that the glide path must be reproducible and free of any obstructions to avoid ledge formation, fracture of instruments, inadequate irrigation, and obturation (van der Vyver, 2014). The operator in this case report followed the above guidelines before the Hyflex EDM Glidepath file was introduced, and the loose 10 K file allowed adequate progression of rotary instrumentation. As stated before, the Hyflex EDM nickeltitanium file range has recently been introduced to the endodontic market by Coltene. The system is unique in its EDM manufacturing process of controlled-memory (CM) nickel-titanium wire. Shen, et al. (2013), stated that CM nickel-titanium wire increases file flexibility and resistance to cyclic fatigue

and also has the ability to limit iatrogenic errors during cleaning and shaping (ledge formation and instrument fractures) of curved canals (Shen, et al., 2013). According to the manufacturer, the instrument also has a “regenerative effect.” The instrument has the ability to return to its original shape after a cycle in the autoclave once unwinding of the flutes is observed. In most cases, only two instruments are needed to complete root canal preparation once a loose number 10 K-file on working length is confirmed. The Hyflex EDM Glidepath file has a tip size of 0.10, and 5% taper, and is operated at a rotation speed of 250 rpm-300 rpm with 1.8 Ncm torque setting, while the Hyflex EDM Onefile has a tip size of 0.25 with an 8% taper in the first 5mms of the cutting Endodontic practice 27

CONTINUING EDUCATION

areas where root canal instruments operate play a vital role in instrument fatigue and fracture (Topcuoğlu, et al., 2016). There is always the possibility that two or more curves can exist in the same root when a tooth is endodontically treated. The presence of a “double curve” or the S-curve as referred to in endodontic circles, can be one of the most challenging scenarios a treating clinician can face. The S-curve causes increased strain on nickel-titanium instruments during cleaning and shaping (Pruett, et al., 1997). The presence of extreme curvature can also be hidden from a clinician in the fact that it may not be visible on conventional radiographs. A study conducted by Al-Sudani, et al. (2012), found that instrument fatigue occurs very quickly once the file encounters a double curvature. Therefore, the treating clinician has a short amount of time for canal preparation, especially in the apical region of these root canals. An investigation of available literature revealed limited information on cyclic fatigue resistance of nickel-titanium endodontic instruments in S-curve canals. Bending stress or cyclic fatigue can be described as the force generated within the nickel-titanium alloy by rotating an instrument in a curved root canal. This will result in repeated compression and flexing at the point of maximum curvature — a very destructive form of loading of the instrument, despite the fact that nickel titanium has superior elasticity, and that there is no binding to the canal wall (Pruett, et al., 1997). In the presented case, the operator utilized a pumping motion with brushing on the outstroke during shaping in an effort to distribute forces over a greater area of the file and reduce the risk of cyclic fatigue and instrument fracture (Al-Sudani, et al., 2012). A factor that could greatly influence the failure rate of nickel-titanium endodontic files is the creation of a glide path. A smooth glide path will allow a relatively safe passage for subsequent rotary instruments to follow. West (2006) described a glide path as a smooth, continuous channel extending from the orifice of the root canal in the pulp chamber to its most apical exit at the apex of the root. Varela-Patiño, et al. (2005), found that fewer fractures occurred when a wide and smooth-walled glide path was created, and the canal was pre-flared before the introduction of rotary files into the root canal. West (2010) suggested that a loose 10 K file moving freely to working length should be considered the minimum size for a glide path before rotary file introduction.

CONTINUING EDUCATION

Figure 11: Coronal portion of obturated material removed from mesio-buccal canal with 40/03 electric heated plugger

Figure 12: Obturation complete in all canals using a combination of cold lateral condensation and warm vertical condensation with electric heated pluggers (EHPs) and Calamus Dual

Figure 13: Mesially-angulated radiographic view separating the roots and illustrating individual obturated canals

tip and then 4% taper from 5 mm-15 mm from the cutting tip. The Onefile is operated at a high rotation speed of 500 rpm with 2.5 Ncm torque setting. The system also include the optional Hyflex EDM 0.25 12% Orifice Opener to create coronal flaring. In the reported case, the operator used a well-lubricated Hyflex EDM Orifice Opener with gentle apical pressure and a brushing motion for coronal enlargement of the orifices. Coronal enlargement reduces torsional resistance, allowing the instrument to progress without the operator using excessive apical force. Torsional resistance can be described as the amount of stress generated within the instrument when it engages the root canal wall or when the operator subjects the instrument to increased apical force (Sattapan, et al., 2000). The controlled memory effect of the Hyflex EDM instruments allows pre-curving and bends to adapt to root canal curvature (Figure 10). This feature enables the instrument to maintain the original root canal shape without the “straightening” effect caused by nickel-titanium file memory. Instruments with a dominant austenite crystalline structure are generally stiffer with increased file memory compared to instruments with martensitic crystalline structure (Aoun, et al., 2017). The unique EDM manufacturing process causes an increase of the austenite finish temperature of the CM-wire alloy. In any instrument where the austenite finish temperature of the file is superior to body temperature, the alloy will be in a mixed martensitic, R-phase, and austenitic structure at root canal temperature at the time of canal preparation. According to literature, the austenite finish temperature of the Hyflex EDM files is 52°C (Iacono, et al., 2017). It can be speculated that Hyflex EDM instruments can maintain most of its

martensitic properties at body temperature during shaping, but further investigation will be required to confirm this speculation. Precurving of CM-wire instruments also facilitates working on teeth with limited access (second and third molars) and allows management of root canals with ledges (Sides, 2012). This statement can be confirmed in the presented case where limited access was encountered, especially the mesio-buccal canal. The precurving advantage enabled the operator to gain adequate access into the root canals. Finally, Topcuoğlu and co-workers (2016) compared CM-wire instruments to traditional nickel-titanium instruments using simulated S-shaped canals. The CM-wire instruments evaluated in this study showed increased

cyclic fatigue resistance compared to traditional nickel-titanium instruments. It can only be speculated whether traditional nickel-titanium instruments would have been able to negotiate the challenging morphology found in the treated case.

28 Endodontic practice

Conclusion The presented case illustrates the ability of the Hyflex EDM rotary file system to safely and efficiently negotiate challenging anatomy in spaces with limited access. The file system also provided sufficient resistance to cyclic and torsional fatigue to treat the S-curve with reduced risk of instrument separation. EP This paper is reprinted from International Dentistry – African Edition 8(3): 82-85.

REFERENCES 1. Aoun CM, Nehme WB, Naaman AS, Khalil. Review and classification of heat treatment procedures and their impact on mechanical behavior of endodontic files. Int J Curr Res. 2017;9:51300-51306 2. Al-Sudani D, Grande NM, Plotino G, et al. Cyclic fatigue of nickel-titanium rotary instruments in a double (S-shaped) simulated curvature. J Endod. 2012;38(7):987-989. 3. Coltene Endo. Next Generation One File NiTi System Hyflex® EDM. Available at: www.coltene.com/fileadmin/Data/EN/Products/ Endodontics/Root_Canal_Shaping/HyFlex_EDM/6846_09-15_HyFlex_EN.pdf. Accessed July 18, 2019. 4. Guo Y, Klink A, Fu C, Snyder J. Machinability and surface integrity of Nitinol shape memory alloy. Manufacturing Technology. 2013;62(1):83-86. 5. Iacono F, Pirani C, Generali L, et al. Structural analysis of HyFlex EDM instruments. Int Endod J. 2017;50(3):303-313. 6. Jameson EC. Description and Development of Dearborn Electrical Discharge Machining. Society of Manufacturing Engineers. Dearborn, Michigan; 2001. 7. Peters OA. Current challenges and concepts in the preparation of root canal systems: a review. J Endod. 2004;30(8):559-567. 8. Pruett JP, Clement DJ, Carnes DL Jr. Cyclic fatigue testing of nickel-titanium endodontic systems. J Endod. 1997;23(2):77-85. 9. Sattapan B, Palamara JEA, Messer HH. Torque during canal instrumentation using rotary nickel-titanium files. J Endod. 2000;26:156-160. 10. Shen Y, Zhou HM, Zheng YF, Peng B, Haapasalo M. Current challenges and concepts of the thermomechanical treatment of nickel-titanium instruments. J Endod. 2013;39(2):163-172. 11. Sides E. Keep your eye on the prize: predictable root canal shaping with the restored tooth in mind. Oral Health. 2012;2:87-93. 12. Topcuoğlu HS, Topcuoğlu G, Akti A, Düzgün S. In vitro comparison of cyclic fatigue resistance of ProTaper Next, HyFlex CM, OneShape, and ProTaper Universal instruments in a canal with a double curvature. J Endod. 2016;42(6):969-971. 13. van der Vyver PJ. ProGlider™: clinical protocol. Endodontic Practice US. 2014;7(6):12-19. 14. Patiño PV, Biedma BM, Liébana CR, Cantatore G, Bahillo JG. The influence of a manual glide path on the separation rate of Ni-Ti rotary instruments. J Endod. 2005;31(2):114-116. 15. Yared G. Canal preparation using only one Ni-Ti rotary instrument: preliminary observations. Int Endod J. 2008;41(4):339-344. 16. West J. Endodontic update 2006. J Esthet Restor Dent. 2006;18(5):280-300. 17. West J. The endodontic glide path: “Secret to rotary safety.” Dent Today. 2010;29(9):86-93.

Volume 12 Number 3

REF: EP V12.3 JONKER

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Please allow 28 days for the issue of the certificates to be posted.

Negotiation of an S-shaped canal with an EDM-machined CM instrument: a case report JONKER

1. _______ can be defined as the process where the shape memory of the nickel-titanium alloy is removed by a special thermomechanical process. a. Controlled memory b. Cryogenic processing c. Bioelectric processing d. Electric discharge processing 2. The EDM procedure is a process where there is no contact between the work piece and manufacturing apparatus, and only a(n) _______ removes parts of the alloy. a. constant electric current b. pulsating electric current c. constant water stream d. evaporation process 3. The metal alloy is immersed in a _________ medium, which allows electric discharge flow between an electrode and the metal alloy. a. bioelectric b. dielectric c. frozen d. nickel-titanium 4. According to the literature, it is well documented that the extent of curvatures in the areas where root canal instruments operate plays a vital role

Volume 12 Number 3

in ________. a. disinfection b. instrument fatigue c. instrument fracture d. both b and c 5. The presence of a _______ can be one of the most challenging scenarios a treating clinician can face. a. “double curve” b. S-curve c. single curve d. both a and b 6. _______ can be described as the force generated within the nickel-titanium alloy by rotating an instrument in a curved root canal. a. Bending stress or cyclic fatigue b. Electric discharge fatigue c. Controlled memory d. Recapitulation 7. Patiño, et al. (2005), found that fewer fractures occurred when a wide and smooth-walled glide path was created, and the canal was pre-flared ______ the introduction of rotary files into the root canal. a. before b. after

c. during d. none of the above 8. West (2010) suggested that a loose ________ moving freely to working length should be considered the minimum size for a glide path before rotary file introduction. a. 04 K-file b. 06 K-file c. 08 K-file d. 10 K-file 9. It must also be emphasized that the glide path must be reproducible and free of any obstructions to avoid ________, and obturation. a. ledge formation b. fracture of instruments c. inadequate irrigation d. all of the above 10. ________ can be described as the amount of stress generated within the instrument when it engages the root canal wall or when the operator subjects the instrument to increased apical force. a. Longitudinal strain b. Torsional resistance c. Compression stress d. Elongation-based tension stress

Endodontic practice 29

CE CREDITS

ENDODONTIC PRACTICE CE

TECHNOLOGY

Join the 80%: CBCT and endodontics Dr. Nestor Cohenca discusses the benefits of using 3D imaging in his endodontic practice

ased on a study published by Setzer, et al., in 2017 in the Journal of Endodontics, 80.3% of endodontists have access to a CBCT; 50.69% have the technology on-site, and 49.31% have access to the technology off-site.1 The technology has proven essential in many fields of dentistry, and we’ve come a long way since large, complicated imaging systems were relegated to universities and reserved for only the most complicated cases. Today, systems are smaller and more capable of meeting the unique needs of endodontists than ever before, making a CBCT system something to consider for your practice and your patients.

pre-surgical assessment — CBCT imaging revolutionized the field. Doctors acknowledged the advantages, but most were reluctant to implement the technology due to its size and cost.2,3 It took a few years, but around 2009, with incentives given to graduate programs that led to further development, research, and clinical experience, the technology developed exponentially.4 Part of that was fueled by the introduction of systems that were more affordable and with a relatively small footprint.

“Wow” imaging for more confident diagnosis and patient confidence My first “wow” moment with CBCT was

during the early years of the technology when scanning a patient after a traumatic dental injury that lead to lateral luxation of the maxillary left central incisor. The CBCT scan was able to produce images that previously had only ever been drawn or imagined. Those stunning 3D images have only gotten better over time. When indicated, 3D imaging provides critical information toward development of the best treatment plan. High-resolution images give endodontists the ability to change course and adapt quickly, if needed, to achieve better outcomes. Being able to diagnose a predictable failure also avoids unnecessary invasive procedures — for example, cases of

A brief history of the CBCT and endodontics Most of the major changes in endodontics, both in concepts and technology, started in the early 2000s. The use of microscopes, biological materials, and rotary instrumentations were some of the most significant advancements in endodontics in the 21st century. Then came CBCT imaging. Initially used in academic institutions — mostly for trauma, root resorptions, and Nestor Cohenca, DDS, completed the endodontic program at the Hebrew University in Jerusalem cum laude and received the Best Graduate Student Award. He then served 11 years on faculty at the school while maintaining a private practice limited to endodontics. From 2003 to 2005, he served as a clinical assistant professor and coordinator of Trauma and Sports Dentistry at the University of Southern California. Thereafter, Dr. Cohenca joined the University of Washington where he completed his endodontic certificate in 2008 and served as Tenured Professor of Endodontics and Pediatric Dentistry from 2005-2014. Currently he serves as Professor at the University of Washington, Professor and Director of Endodontics and the Multidisciplinary Traumatology Unit at Seattle Children’s Hospital, and maintains a private practice limited to endodontics in Seattle and Kirkland, Washington. He is a Diplomate of the Israel Board of Endodontics and the American Board of Endodontics. Dr. Cohenca is a Fellow and Past-President of the International Association of Dental Traumatology and received an honorary membership to Omicron Kappa Upsilon National Dental Honor Society. He has published more than 80 peer-reviewed articles, 10 chapters, and a new book titled Disinfection of Root Canal Systems: The Treatment of Apical Periodontitis. Dr. Cohenca provided more than 200 lectures around the world and is well known as one of the experts in dental traumatology, endo-pedo-related topics, vital pulp therapy, CBCT, and root canal disinfection. Disclosure: Dr. Cohenca is a key opinion leader for Carestream Dental.

30 Endodontic practice

Figures 1A-1D: 1A-1B. Periapical radiographs from different angles. Patient was referred for endodontic therapies on teeth Nos. 19 and 20 with apical lucencies consistent with apical periodontitis. Initially, a nonsurgical root canal treatment on tooth No. 20 and retreatment on tooth No. 19 were recommended. CBCT was taken for further diagnosis and treatment planning. 1C. Axial slide demonstrating a severe inflammatory external root resorption on the buccal surface of the distal root of tooth No. 19. 1D. The presence of a vertical root fracture on the buccal surface of tooth No. 20 was noted and confirmed. Based on the information obtained on the 3D CBCT, both teeth were deemed with unfavorable prognosis, and extraction was recommended Volume 12 Number 3

Rather than trying different procedures with unpredictable results, CBCT imaging can save patients time, money, and stress — by excluding unsavable teeth from the very start of the treatment plan. An additional benefit of CBCT imaging is differential diagnosis of chronic pain. Instead of prescribing medication to treat the symptoms, CBCT has the potential to instantly reveal the underlying problem, allowing the clinician to provide the correct treatment and relief.

Invest in hardware, reap the benefit of software Today, CBCT imaging is driven by advanced software algorithms. That means

that the software powering these systems is just as important as the equipment itself. The quality of the 3D scans, the ease of use, and the ability to share scans with referrals all come down to software. Ultimately, the hardware will not change much in the coming years; however, software updates and other new features and improvements must be pushed out by the manufacturer to ensure doctors are always practicing with the most advanced technology. Some examples of these updates can lead to improved image quality, digital measurements and reconstructions, metal artifact reduction (MAR), and therapeutic guides for surgical and nonsurgical cases.

Spreading the word about CBCT If you’re still on fence about CBCT, why not experience it for yourself? Webinars, study clubs, trade shows, and hands-on events give doctors every opportunity to explore their CBCT options. In fact, after setting up my new practice and installing a CS 8100 3D (Carestream Dental), I recently founded the Kirkland Study Club with the purpose of creating a multidisciplinary group of professionals willing to share and learn from each other. The first meeting covered a topic relevant to anyone looking to learn more about what CBCT could do for their patients and practice: “Clinical Applications of CBCT in Endodontics.” Upcoming meetings will cover topics such as advanced Invisalign® concepts; immediate implant placement; non-invasive dentistry; keys to managing growth and eruption in the mixed dentition; and more. Additionally, Carestream Dental makes it easy for doctors looking to get a sample of CBCT imaging at carestream dental.com/3D with a digital library of 3D imaging resources. Studies and research show more and more the benefits of CBCT in endodontics, and 80% of the profession can’t be wrong. Join us on the other side with enhanced imaging, improved diagnosis, and better patient care. EP

REFERENCE 1. Setzer FC, Hinckley N, Kohli MR, Karabucak B. A survey of cone-beam computed tomographic use among endodontic practitioners in the United States. J Endod. 2017;43(5):699-704. 2. Cohenca N, Simon JH, Roges R, Morag Y, Malfaz JM. Clinical indications for digital imaging in dento-alveolar trauma. Part 1: Traumatic Injuries. Dent Traumatol. 2007;23(2):95-104

Figures 2A- 2D: Periapical radiographs from different angles. Patient presented immediately after a traumatic injury to maxillary anterior teeth. 2A-2B. Clinical and radiographic examination was performed, and teeth Nos. 7, 8, and 9 were diagnosed with a complicated crown fracture (with pulp exposure). A vital partial pulpotomy was initially planned and recommended. CBCT was taken for further diagnosis and treatment planning. 2C-2D. Sagittal and coronal slides demonstrating a crown-root fracture on tooth No. 7, extending to the crestal bone. Treatment plan was modified accordingly Volume 12 Number 3

3. Cohenca N, Simon JH, Mathur A, Malfaz JM. Clinical indications for digital imaging in dento-alveolar trauma. Part 2: Root resorption. Dent Traumatol. 2007;23(2):105-113 4. Patel S, Brown J, Pimentel T, Kelly RD, Abella F, Durack C. Cone beam computed tomography in Endodontics a review of the literature. Int Endod J. 2019 Mar 14. doi: 10.1111/iej.13115.

Endodontic practice 31

TECHNOLOGY

root fractures or deep cracks (Figure 1). For root canal retreatments, understanding the etiology of the disease or failure is critical to obtaining a positive outcome. CBCT also aids with enhanced visualization of traumatic injuries, particularly for crown, root fractures, and luxation injuries (Figure 2). Ultimately, the more accurate and realistic assessments of prognoses, the more predictable and positive outcome for my patients. From patients’ perspective, the “wow” moments happen daily when they can see their jaw and teeth moving three-dimensionally. More important, the fact that patients can now see the problem and understand the available treatment options is critically important to obtain an informed decision.

RESEARCH

Influence of different irrigation solutions in the adhesive resistance of glass fiber posts on bovine radicular dentin Drs. Tiago André Fontoura de Melo and Daniel Galafassi, along with Cláudia Wagner, Bruna Machado dos Passos, and Priscila Souza de Souza, analyze the influence of an intracanal irrigating solution Abstract This study aims to analyze the influence of the intracanal irrigating solution on the adhesive strength of cemented intraradicular fiberglass posts with RelyX™ U200. Sixty bovine lower incisors were randomly divided into six experimental groups according to the irrigation solution used in the mechanical chemical preparation: CN - saline, CP - saline + EDTA, CLX - 2% chlorhexidine digluconate, CLXE - 2% chlorhexidine digluconate + EDTA, HIP - 2.5% sodium hypochlorite, and HIPE - 2.5% sodium hypochlorite + EDTA. The root canals were filled with AH Plus®. After 72 hours in the greenhouse, the teeth were unthreaded to receive the fiberglass post cemented with RelyXTM U200. The samples were then sectioned in 1 mm according to the root thirds and subjected to the push-out test. After the test, the fractured samples were analyzed in a 20X stereomicroscope to determine the type of fracture. The obtained data was treated by the ANOVA two-way test, followed by the Tukey test. The non-parametric Kruskal-Wallis test was used to analyze the fracture type. The level of significance was 5%. There was a significant difference between irrigation solutions only in the middle-third of the root canal. In the association of saline solution with EDTA, there was a higher adhesion strength when

Tiago André Fontoura de Melo holds a PhD in endodontics and is a teacher in the Department of Conservative Dentistry, Dental School, Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, Brazil. Daniel Galafassi holds a PhD in dentistry and is a teacher in the Clinical Department, Dental School, College of Serra Gaúcha (FSG), Caxias do Sul/RS, Brazil. Cláudia Wagner holds an MSc in endodontics and is a teacher in the Clinical Department, Dental School, College of Serra Gaúcha (FSG), Caxias do Sul/RS, Brazil. Bruna Machado dos Passos and Priscila Souza de Souza are graduate students in the Clinical Department of the Dental School, College of Serra Gaúcha (FSG), Caxias do Sul/RS, Brazil.

32 Endodontic practice

Table 1: Table demonstrating experimental groups Experimental groups

Irrigating solutions

EDTA

saline solution

Yes

CLX

chlorhexidine digluconate 2%

CLXE

chlorhexidine digluconate 2%

Yes

HIP

sodium hypochlorite 2.5%

HIPE

sodium hypochlorite 2.5%

Yes

compared to chlorhexidine and sodium hypochlorite associated with EDTA. The predominant type of failure was adhesive, with no difference between the different irrigation solutions.

Introduction The use of prefabricated posts in the rehabilitation procedure of endodontically treated teeth has been widely used in dentistry (Castro, et al., 2012). The use of fiberglass posts has provided a better distribution of masticatory loads when compared to metal posts because their modulus of elasticity is very similar to that of dentin tissue (Newman, et al., 2003). However, one factor much discussed in the literature is the stability and longevity of these esthetic posts. Several factors may be related to the failure of intraradicular material retention, such as the adhesive system and cement used and the type of dentin treatment performed before cementation (Cecchin, et al., 2011; Pereira, et al., 2013). The adhesives and cements available in the market are very varied, and each material, depending on the composition and properties, may respond differently to endodontic treatments (Oliveira, et al., 2007). Therefore, it is important to analyze the changes that they can cause in the adhesion of the posts in the dentin. The adhesion strength tested in obturations was dissimilarly affected when using different irrigation solutions (Hashem, et

al., 2009). Depending on the type of irrigation solution used during mechanical chemical preparation, a change in the adhesion of the post to the intraradicular dentin may occur. The sodium hypochlorite solution decomposes in sodium chloride and oxygen, and this oxygen can inhibit the polymerization of resin cement and dentin adhesive (Nikaido, et al., 1999), as well as to promote the formation of bubbles that may interfere with resin infiltration within dentinal tubules (Ari, et al., 2003). Chlorhexidine digluconate does not dissolve organic components (Dametto, et al., 2005) and therefore may not facilitate the entry of the adhesive monomer into the dentinal tubules. Also, because of its adsorption characteristics, chlorhexidine digluconate may influence the adhesion strength of cemented posts in the root canal. Thus, the purpose of this study is to analyze, by means of a mechanical pushout test, the influence of the type of intracanal irrigating solution on the adhesion of cemented intraradicular glass fiber posts with RelyXTM U200. The null hypothesis is that none of the irrigating solutions will influence the union force.

Methods Selection and preparation of samples Sixty bovine lower incisors intact and with complete rhizogenesis were selected, with the initial apical diameter of the root canal standardized with an endodontic Volume 12 Number 3

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RESEARCH instrument K-type No. 40 (Dentsply/Maillefer Instruments S.A., Ballaigues, Switzerland). The dental crowns were sectioned at the cementoenamel junction, with the aid of diamond discs (American Burrs, Porto Alegre, Rio Grande do Sul, Brazil), in low rotation and under refrigeration. The length of the root remainder was standardized at 17 mm, and the working length (WL) was 1 mm below this measurement (WL = 16 mm). Division of experimental groups Samples were randomly divided into six experimental groups according to Table 1. Endodontic treatment of the samples All samples were manually prepared by the crown-apex technique with firstand second-series K-type stainless steel endodontic instruments (Dentsply/Maillefer Instruments S.A., Ballaigues, Switzerland). The diameter of the apical preparation was standardized with the use of instrument No. 60 in WL. At each instrument change, the canals were irrigated with a plastic syringe (BD Solumed, São Paulo, São Paulo, Brazil) and NaviTip 25 mm 30ga needles (Ultradent, Indaiatuba, São Paulo, Brazil; South Jordan, Utah) with 2 mL of 2.5% sodium hypochlorite (Iodontec Indústria e Comércio de Produtos Odontológicos Ltda., Porto Alegre, Rio Grande do Sul, Brazil). After the preparation, the final disinfection with filling of the root canal with 17% EDTA (Biodinamica, Ibiporã, Paraná, Brazil) was carried out under shaking of instrument No. 60 for 3 minutes. The canals were then irrigated with 2 mL of saline solution (Farmax, Divinópolis, Minas Gerais, Brazil) and dried with sterile absorbent paper tips No. 60 (Dentsply/Maillefer Instruments S.A., Ballaigues, Switzerland). No intracanal medications were placed inside the canals; the samples were filled using AH Plus® cement (Dentsply/Maillefer Instruments S.A., Ballaigues, Switzerland) and the Tagger Hybrid Technique. The endodontic cement was proportioned and spatulated according to the manufacturer’s recommendations, and then the main tips of gutta percha No. 60 (Dentsply/Maillefer Instruments S.A., Ballaigues, Switzerland) were wrapped in cement and introduced into the WL. After insertion of the fifth accessory tip (Dentsply/Maillefer Instruments SA, Ballaigues, Switzerland) with the aid of the bidigital spacer B (Dentsply/Maillefer Instruments SA, Ballaigues, Switzerland), during lateral condensation, gutta-percha tips were plasticized by means of a McSpadden® No. 60 (Dentsply/Maillefer Instruments S.A., 34 Endodontic practice

Figure 1: Test of the push-out test: A and B (test body positioned on the universal test machine) and C (schematic drawing of the push-out test)

Ballaigues, Switzerland) calibrated at 4 mm below the WL, in order to obturate the middle and cervical thirds of the canal. After the gut plastification, the vertical condensation of the material was carried out with the aid of the Paiva No. 2 (S.S. White, Rio de Janeiro, Rio de Janeiro, Brazil; Lakewood, New Jersey). The samples were provisionally restored to the cervical third with Cavit® (Septodont, Pomerode, Santa Catarina, Brazil; Lancaster, Pennsylvania) and remained immersed in a bottle containing distilled water (Iodontec Indústria e Comércio de Produtos Odontológicos Ltda., Porto Alegre, Rio Grande do Sul, Brazil) in an oven at 37 °C and 100% relative humidity for 2 days to ensure the complete setting of the endodontic cement. Re-preparation of the canal and cementation of the fiberglass post The canals were re-prepared using a DC2 drill (Whitepost, FGM, Joinville, Santa Catarina, Brazil) at a depth of 12 mm, with 4 mm of the obturator material remaining in the apical third. Before cementation of the fiberglass posts, the canals were irrigated with 2.5% sodium hypochlorite solution and dried with absorbent paper tips, as recommended by the adhesive cement manufacturer. With the dry canal, saline (FGM Produtos Odontológicos, Joinville, Santa Catarina, Brazil) was applied and dried at room temperature followed by application of air jets at a distance of 15 cm for 1 minute. The resinous cement RelyX™ U200 (3M/ESPE, Saint Paul, Minnesota) was applied to the root canal using a centrix syringe (DFL, Rio de Janeiro, Rio de Janeiro, Brazil) with a metal tip. The post was introduced into the root canal and filled with cement to the coronal portion to seal well the entrance and photoactivation with the aid of EC450 (ECEL, Ribeirão Preto, São Paulo, Brazil) for 40 seconds (20 seconds on each face: vestibular and lingual). The fiberglass posts used in the experiment were No. 2 (Angelus, Londrina, Paraná, Brazil). They were cleaned prior to use with alcohol 70 (Icarai, São Paulo, São Paulo, Brazil).

The samples were stored in distilled water for 48 hours to ensure the setting of the resin cement. Shear extrusion test (push-out) The samples were sectioned perpendicular to the long axis of the root with a diamond disk (American Burrs, Porto Alegre, Rio Grande do Sul, Brazil) in low rotation under refrigeration. A first cervical portion, approximately 1 mm thick, was discarded, as inherent imperfections in the adhesive zone, due mainly to the presence of oxygen, may influence the results (Van Noort, et al., 1991). Then three slices of approximately 1 mm thickness were obtained, one of the cervical third, one of the middle-third, and the other of the apical third. After cutting each slice, markings with an overhead pen were made on the cervical surface of the sample in order to highlight this face for later positioning of the piece at the time of the test. Then during the push-out test, each sample was placed on a metal device with a central opening larger than the canal diameter. The slices always remained with the cervical side down, facilitating the extrusion of the canal post/cement, which already presented with a conical shape, thus leaving the part of larger diameter down. For the push-out test, an adapted metal cylinder (Ø = 1 mm) induced loading on the central portion of the post/cement, without the load being applied to the dentin (Figure 1). The test was performed in a universal test machine (Instron® EMIC, São José dos Piñhais, Paraná, Brazil; Instron® Worldwide Headquarters, Norwood, Massachusetts) with a velocity of 0.5 mm/min and a load of 50 N (newton). The results were recorded in Newton and later converted to Mpa (Megapascal). The adhesion area (A) was calculated by the formula (2πr) multiplied by the height (L). The force (F) that occurred the fault were recorded in N and converted to Mpa. The adhesive resistance to the pushout was measured by dividing the force (F) by the adhesion area (A). Volume 12 Number 3

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RESEARCH Analysis of fracture type After the push-out test, the fractured samples were stained with 7% hematoxylin for 3 minutes and analyzed in X20 stereomicroscope (Stemi 2000, Carl Zeiss, Germany; Carl Zeiss Meditec, Inc., Dublin, California) with a 50-fold increase in fracture type determination: • Cohesive on the dental substrate — fracture predominantly (about 75%) within the dental structure • Cohesive in the cement — fracture predominantly (about 75%) inside the cement • Adhesive — fracture at the adhesive interface/dental structure or adhesive/cement interface in more than 75% of the analyzed area • Mixed — fractures with no predominance greater than 75% of any type of failure (Le Bell, et al., 2004) Statistical analysis The obtained data was tabulated and submitted to two-way ANOVA followed by Tukey’s test, for multiple comparisons. The non-parametric Kruskal-Wallis test was used to analyze the fracture type. The level of significance was 5% (P ≤ 0.05). Statistical analysis was performed using SPSS 13.0 software (SPSS Inc., Chicago, Illinois).

Table 2: Mean and standard deviation of the experimental groups in relation to the root thirds Root thirds Experimental groups

Middle

Apical

Mean SD

9.49 ± 3.75

5.20

4.71Ab ± 3.52

0.006

6.87Aa ± 4.24

6.71Aa ± 3.08

4.45Aa ± 3.27

0.255

CLX

6.86Aa ± 2.67

4.34ABab ± 2.96

2.38Ab ± 1.63

0.002

CLXE

8.93 ± 4.15

2.44

2.76 ± 2.70

0.001

HIP

7.45 ± 3.76

4.26

2.59 ± 2.97

0.001

HIPE

4.99 ± 2.87

2.84 ± 2.23

2.44 ± 4.18

0.177

0.093

0.021

0.350

36 Endodontic practice

ABb

± 2.76

± 1.58

ABab

± 4.12

Ab Aa

Table 3: Analysis of the types of failures that occurred in the experimental groups in each of the three-thirds of the root canal Third

Cervical

Middle

Results The mean values of the adhesion strength values (Mpa) of the different experimental groups in the different regions of the canal are shown in Table 2. Means followed by distinct uppercase letters in the column and averages followed by different lowercase letters in the row differ significantly by means of the two-way ANOVA followed by Tukey’s test at a significance level of 5%. The ANOVA two-way test, followed by the Tukey’s test, showed a significant statistical difference between the positive control group (CP) and the CLXE and HIPE groups (P = 0.021) only in the middle-third of the root canal. When analyzing the experimental groups by root thirds, a significant statistical difference was observed between the cervical third in relation to the middle and apical for the CN, CLX CLXE, and HIP experimental groups (P <0.05). For analysis of the fracture type (Table 3), it can be observed that, although the predominant pattern of defects was adhesive, there was no difference between the groups tested in relation to the threethirds root.

Cervical

Apical

Type of failure

CLX

CLXE

HIP

HIPE

Cohesive – Substrate

Cohesive – Cement

Adhesive

Mixed

Cohesive – Substrate

Cohesive – Cement

Adhesive

Mixed

Cohesive – Substrate

Cohesive – Cement

Adhesive

Mixed

Discussion According to Ari, et al. (2003), the type of irrigation solution used in the mechanical preparation of the root canal can cause deleterious effects on the bonding of the adhesive agents to the dentin structures. Therefore, the present study seeks to analyze if the type of endodontic irrigator influences the adhesion strength of intracanal cemented prefabricated posts. Considering the irrigating solutions, it was decided to analyze 2.5% sodium hypochlorite and 2% chlorhexidine digluconate because they are the most used in endodontic treatment. The choice of physiological saline for use in the control groups is that it is an inert substance and does not present chemical action on the dentin tissues (Camilotti, et al., 2013). As in other studies, canal obturation was performed shortly after mechanical chemical preparation to simulate endodontic treatment in a single session (Topcu, et al., 2010) and to avoid the influence of calcium hydroxide

P=0.365

P=0.112

P=0.222

(Cohen, et al., 2002), used as intracanal medication. According to Dimitrouli, et al. (2011), another factor that may also negatively influence the adhesive strength of glass fiber posts is the composition of certain endodontic cements. The cement of choice for the obturation of the study samples was based on epoxy resin AH Plus® because according to Kurtz, et al. (2003), this cement does not change the adhesive strength in the cementation process. As in the study by Kirmali, et al. (2017), the use of the push-out test is a widely used feature in laboratory research to evaluate multiple factors that may influence intraradicular post retention. Another important detail is that, according to Goracci, et al. (2004), the push-out test represents the clinical situation better. Initially, in the analysis of the results of the study, it can be observed that the type of irrigating solution influenced the adhesion strength of the intraradicular cemented glass Volume 12 Number 3

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TIC

RESEARCH fiber post in its middle-third, thus rejecting the null hypothesis presented in the objective. In the analysis of irrigation solutions tested, associated or not to EDTA, it can be observed that there was a difference of adhesion to cementation of the post only in the middle-third of the canal. In the cervical and apical thirds, the behavior was equal between the groups. For Ozturk and Ozer (2004) and Arisu, et al. (2002), the use of intracanal sodium hypochlorite adversely affects the bond strength of resin cement, significantly reducing the modulus of elasticity of dentin (Marending, et al., 2007). Furthermore, because sodium hypochlorite dissociates in sodium chloride and oxygen, nascent oxygen can cause a strong inhibition of polymerization at the cementation interface (Greenstein, et al., 1986). In the study by Marques, et al. (2014), it can be observed that the use of 2.5% sodium hypochlorite significantly reduced adhesion strength, while the 2% chlorhexidine digluconate had no effect, as in Leitune, et al. (2010), and Lindblad, et al. (2010). The adhesion of the dentin-resin interface can be compromised by degradation of the adhesive system components due to water absorption and/or proteolytic degradation of the hybrid layer, which is related to the action of metalloproteinases (Cecchin, et al., 2011) and cysteines cathepsin (Tersariol, et al., 2010). Some studies address the inhibition power of matrix metalloproteinases (MMPs) by chlorhexidine (Gendron, et al., 1999). For Brackett, et al. (2009), this inhibitory capacity may prevent the degradation of the relevant smear layer in dentin adhesion. In 2010, Topcu, et al. found that chlorhexidine digluconate favored adhesive resistance when compared to sodium hypochlorite and serum. However, in our study, no influence was observed on adhesion strength when chlorhexidine was used as an irrigant, associated or not with the use of EDTA 17%, in relation to the other irrigants tested. One of the results in the data that drew attention was a lower adhesion strength obtained in the groups that made the association of the irrigant with the EDTA, although without significant difference on some occasions. This may be justified in some ways, since EDTA, as well as chlorhexidine, is also an inhibitor of MMPs (Faria and Silva, et al., 2013). In addition, the type of resin cement used in our study (RelyX™ U200), because it is self-adhesive, has a high potential of chemical reaction with dentin and may have its adhesion capacity impaired by the presence of demineralized apatite in the dentin caused by chelating action of EDTA itself. 38 Endodontic practice

Other data presented by some experimental groups (CN, CLX, CLXE, and HIP) and that generated reflection was that the force of adhesion in the cervical third of the canal was greater than in the middle and apical thirds. This finding was also observed in the study by Miguel Almeida, et al. (2012). It is believed that this result is not directly related to the type of irrigant tested, but rather to the fact that the photopolymerization of the cement in the cervical third is more effective than in the deep thirds of the root canal, which provides an increase in the adhesive resistance in this region (Hiraishi, et al., 2005). In addition, we also have the distribution and density of dentinal tubules in the different thirds of the root canal that can be correlated to this situation. The tubule density is higher in the cervical third than in the apical region of the root canal, and the tubule diameter decreases apically (Ferrari, et al., 2000). These anatomical variabilities suggest a greater adhesion near the cervical region (Topcu, et al., 2010). Although there was no difference between the different irrigation solutions tested, the failures observed after the pushout test were predominantly adhesive. These results are consistent with other studies such as that of Bitter, et al. (2013) and Kirmah, et al. (2017), who observed the same fracture pattern.

Conclusions According to the results, it can be concluded that, for the cervical and apical thirds, the irrigation solutions did not alter the adhesion process in the cementation of fiberglass posts. The EDTA-associated saline promoted a greater adhesion strength. The type of failure in the predominant fracture process was of adhesive origin. EP REFERENCES 1. Ari H, Yasar E, Belli S. Effects of NaOCl on bond strengths of resin cements to root canal dentin. J Endod. 2003;29(4):248-251. 2. Arisu HD, Kivanç BH, Sağlam BC, Şimşek E, Görgül G. Effect of post-space treatments on the push-out bond strength and failure modes of glass fibre posts. Aust Endod J. 2013;39(1):19-24. 3. Bitter K, Hambarayan A, Neumann K, Blunck U, Sterzenbach G. Various irrigation protocols for final rinse to improve bond strengths of fiber posts inside the root canal. Eur J Oral Sci. 2013;121(4):349-354. 4. Brackett MG, Tay FR, Brackett WW, et al. In vivo chlorhexidine stabilization of hybrid layers of an acetone-based dentin adhesive. Oper Dent. 2009;34(4):379-383. 5. Camilotti V, Ioris MD, Busato PMR, Ueda K, Mendonça MJ. Evaluation of influence of irrigation solution in strength adhesive of a resin cement. Rev Odontol UNESP. 2013;42(2):83-88. 6. Castro CG, Santana FR, Roscoe MG, et al. Fracture resistance and mode of failure of various types of root filled teeth. Int Endod J. 2012;45(9):840-847. 7. Cecchin D, de Almeida JF, Gomes BP, Zaia AA, Ferraz CC. Influence of chlorhexidine and ethanol on the bond strength and durability of the adhesion of the fiber posts to root dentin using a total etching adhesive system. J Endod. 2011;37(9):1310-1315.

8. Cohen BI, Volovich Y, Musikant BL, Deutsch AS. The effects of eugenol and epoxy-resin on the strength of a hybrid composite resin. J Endod. 2002;28(2):79-82. 9. Dametto FR, Ferraz CC, Gomes BP, et al. In vitro assessment of the immediate and prolonged antimicrobial action of chlorhexidine gel as an endodontic irrigant against Enterococcus faecalis. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2005;99(6):768-772. 10. Dimitrouli M, Günay H, Geurtsen W, Lührs AK. Push-out strength of fiber posts depending on the type of root canal filling and resin cement. Clin Oral Investig. 2011; 15(2):273-281. 11. Faria e Silva AL, Menezes MS, Silva FP, Reis GR, Moraes RR. Intra-radicular dentin treatments and retention of fiber posts with self-adhesive resin cements. Braz Oral Res. 2013;27(1):14-19. 12. Ferrari M, Mannocci F, Vichi A, Cagidiaco MC, Mjör IA. Bonding to root canal: structural characteristics of the substrate. Am J Dent. 2000;13(5):255-260. 13. Gendron R, Grenier D, Sorsa T, Mayrand D. Inhibition of the activities of matrix metalloproteinases 2, 8, and 9 by chlorhexidine. Clin Diagn Lab Immunol. 1999;6(3):437-439. 14. Goracci C, Tavares AU, Fabianelli A, et al. The adhesion between fiber posts and root canal walls: comparison between microtensile and push-out bond strength measurements. Eur J Oral Sci. 2004;112(4):353-361. 15. Greenstein G, Berman C, Jaffin R. Chlorhexidine. An adjunct to periodontal therapy. J Periodontol. 1986;57(6):370-377. 16. Hashem AA, Ghoneim AG, Lutfy RA, Fouda MY. The effect of different solutions on bond strength of two root canal-filling systems. J Endod. 2009;35(4):537-540. 17. Hiraishi N, Papacchini F, Loushine RJ, et al. Shear bond strength of Resilon to a methacrylate-based root canal sealer. Int Endod J. 2005;38(10):753-763. 18. Kırmalı Ö, Üstün Ö, Kapdan A, Kuştarcı A. Evaluation of various pretreatments to fiber post on the push-out bond strength of root canal dentin. J Endod. 2017;43(7):1180-1185. 19. Kurtz JS, Perdigão J, Geraldeli S, Hodges JS, Bowles WR. Bond strengths of tooth-colored posts, effect of sealer, dentin adhesive, and root region. Am J Dent. 2003;16(Spec No):31A-36A. 20. Le Bell AM, Tanner J, Lassila LV, Kangasniemi I, Vallittu P. Bonding of composite resin luting cement to fiberreinforced composite root canal posts. J Adhes Dent. 2004;6(4):319-325. 21. Leitune VC, Collares FM, Werner Samuel SM. Influence of chlorhexidine application at longitudinal push-out bond strength of fiber posts. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2010;110(5):77-81. 22. Lindblad RM, Lassila LV, Salo V, Vallittu PK, Tjäderhane L. Effect of chlorhexidine on initial adhesion of fiber-reinforced post to root canal. J Dent. 2010;38(10):796-801. 23. Marending M, Luder HU, Brunner TJ, et al. Effect of sodium hypochlorite on human root dentine — mechanical, chemical and structural evaluation. Int Endod J. 2007;40(10):786-793. 24. Marques EF, Bueno CE, Veloso HH, Almeida G, Pinheiro SL. Influence of instrumentation techniques and irrigating solutions on bond strength of glass fiber posts to root dentin. Gen Dent. 2014;62(2):50-53. 25. Miguel-Almeida ME, Azevedo ML, Rached-Júnior FA, et al. Effect of light-activation with different light-curing units and time intervals on resin cement bond strength to intraradicular dentin. Braz Dent J. 2012;23(4):362-366. 26. Newman MP, Yaman P, Dennison J, Rafter M, Billy E. Fracture resistance of endodontically treated teeth restored with composite post. J Prosthet Dent. 2003;89(4):360-367. 27. Nikaido T, Takano Y, Sasafuchi Y, Burrow MF, Tagami J. Bond strengths to endodontically-treated teeth. Am J Dent. 1999;12(4):177-180. 28. Oliveira LD, Carvalho CA, Nunes W, et al. Effects of chlorhexidine and sodium hypochlorite on the microhardness of root canal dentin. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2007;104(4):125-128. 29. Ozturk B, Ozer F. Effect of NaOCl on bond strengths of bonding agents to pulp chamber lateral walls. J Endod. 2004;30(5):362-365. 30. Pereira JR, Lins do Valle A, Ghizoni JS, et al. Push-out bond strengths of different dental cements used to cement glass fiber posts. J Prosthet Dent. 2013;110(2):134-140. 31. Tersariol IL, Geraldeli S, Minciotti CL, et al. Cysteine cathepsins in human dentin-pulp complex. J Endod. 2010;36(3):475-481. 32. Topcu FT, Erdemir U, Sahinkesen G, Mumcu E, Yildiz E, Uslan I. Push-out bond strengths of two fiber post types bonded with different dentin bonding agents. J Biomed Mater Res B Appl Biomater. 2012;100(5):1458. <RETRACTED ARTICLE> 33. Van Noort R, Cardew GE, Howard IC, Noroozi S. The effect of local interfacial geometry on the measurement of the tensile bond strength to dentin. J Dent Res. 1991;70(5):889-893.

Volume 12 Number 3

AUTHOR GUIDELINES Endodontic Practice US is a peer-reviewed, quarterly publication containing articles by leading authors from around the world. Endodontic Practice US is designed to be read by specialists in Endodontics, Periodontics, Oral Surgery, and Prosthodontics.

Submitting articles Endodontic Practice US requires original, unpublished article submissions on endodontic topics, multidisciplinary dentistry, clinical cases, practice management, technology, clinical updates, literature reviews, and continuing education. Typically, clinical articles and case studies range between 1,500 and 3,000 words. Authors can include up to 15 illustrations. Manuscripts should be double-spaced, and all pages should be numbered. Endodontic Practice US reserves the right to edit articles for clarity and style as well as for the limitations of space available. Articles are classified as either clinical, continuing education, technology, or research reports. Clinical articles and continuing education articles typically include case presentations, technique reports, or literature reviews on a clinical topic. Research reports state the problem and the objective, describe the materials and methods (so they can be duplicated and their validity judged), report the results accurately and concisely, provide discussion of the findings, and offer conclusions that can be drawn from the research. Under a separate heading, research reports provide a statement of the research’s clinical implications and relevance to endodontics. Clinical and continuing education articles include an abstract of up to 250 words. Continuing education articles also include three to four educational aims and objectives, a short “expected outcomes” paragraph, and a 10-question, multiple-choice quiz with the correct answers indicated. Questions and answers should be in the order of appearance in the text, and verbatim. Product trade names cited in the text must be accompanied by a generic term and include the manufacturer, city, and country in parentheses. Additional items to include: • Include full name, academic degrees, and institutional affiliations and locations • If presented as part of a meeting, please state the name, date, and location of the meeting • Sources of support in the form of grants, equipment, products, or drugs must be disclosed • Full contact details for the corresponding author must be included • Short author bio • Author headshot Volume 12 Number 3

Pictures/images

Disclosure of financial interest

Illustrations should be clearly identified, numbered in sequential order, and accompanied by a caption. Digital images must be high resolution, 300 dpi minimum, and at least 90 mm wide. We can accept digital images in all image formats (preferring .tif or jpeg).

Authors must disclose any financial interest they (or family members) have in products mentioned in their articles. They must also disclose any developmental or research relationships with companies that manufacture products by signing a “Conflict of Interest Declaration” form after their article is accepted. Any commercial or financial interest will be acknowledged in the article.

Tables Ensure that each table is cited in the text. Number tables consecutively and provide a brief title and caption (if appropriate) for each.

References References must appear in the text as numbered superscripts (not footnotes) and should be listed at the end of the article in their order of appearance in the text. The majority of references should be less than 10 years old. Provide inclusive page numbers, volume and issue numbers, date of publication, and all authors’ names. References should be submitted in American Medical Association style. For example: Journals: (Print) Greenwall L. Combining bleaching techniques. Aesthetic & Implant Dentistry. 2000;1(1):92-96. (Online) Author(s). Article title. Journal Name. Year; vol(issue#):inclusive pages. URL. Accessed [date].

Manuscript Review All clinical and continuing education manuscripts are peer reviewed and accepted, accepted with modification, or rejected at the discretion of the editorial review board. Authors are responsible for meeting review board requirements for final approval and publication of manuscripts.

Proofing Page proofs will be supplied to authors for corrections and/or final sign off. Changes should be limited to those that are essential for correctness and clarity. Articles should be submitted to: Mali Schantz-Feld, managing editor mali@medmarkmedia.com

Reprints/Extra issues If reprints or additional issues are desired, they must be ordered from the publisher when the page proofs are reviewed by the authors. The publisher does not stock reprints; however, back issues can be purchased.

Or in the case of a Book: Greenwall L. Bleaching techniques in Restorative Dentistry: An Illustrated Guide. London: Martin Dunitz; 2001. Website: Author or name of organization if no author is listed. Title or name of the organization if no title is provided. Name of website. URL. Accessed Month Day, Year. Example of Date: Accessed June 12, 2011. Author’s name: (Single) Doe JF

(Multiple) Doe JF, Roe JP

Permissions Written permission must be obtained by the author for material that has been published in copyrighted material; this includes tables, figures, pictures, and quoted text that exceeds 150 words. Signed release forms are required for photographs of identifiable persons.

Checklist for article submissions: 3 A copy of the manuscript and figures, captions, including all pictures (low res) necessary for reviewers 3 Manuscript: double-spaced including separate references, figure legends, and tables 3 Abstract, educational objectives, expected outcomes paragraph 3 References: double-spaced, alphabetical, American Medical Association style 3 Tables: titled and cited in the text 3 Mandatory submission form, signed by all authors Please contact managing editor Mali SchantzFeld with any questions via email: Mali@medmarkmedia.com

Endodontic practice 39

PRODUCT PROFILE

What’s new in my sponge? Dr. Brett E. Gilbert discusses his experience with the Traverse™ glide path file system

hen it comes to adopting new instruments into my endodontic protocol, I am a harsh critic and scrutinize every detail of the new armamentarium. For many years, I have recognized the merits and usefulness that a glide path rotary file could provide to canal preparation. Although I knew that the engineering of glide path files was very advanced, until recently, I could not commit to running these files into root canals that had not been established by hand-filing the glide path first. Why, you might ask? The answer is simple — trust. I did not trust that these rotary glide path files would not separate in the canal before having some degree of debridement completed by the safety use of hand filing first. My mind was changed with the introduction of the Traverse™ glide path file system. I was intrigued by my initial testing of these files and the strength and flexibility that they demonstrated while using them in extracted teeth. Upon engagement into the canals, the files were able to withstand my toughest testing (pushing them harder than I would in a clinical situation). After several rounds of in vitro testing, I felt confident in the performance of these files and decided to incorporate them into my patient treatment. I had some skepticism, combined with hope, that this might be the rotary glide path file system for which I had been waiting. As a practicing endodontist for 16 years, I have become well aware of the toll that clinical practice takes on the body. I am constantly searching for ways to incorporate technology to take the pressure off of me, allowing me to work longer and stronger. Eliminating extensive hand filing is one way to create increased efficiency in my treatment protocol and also to take strain off of my body. The Traverse system is a new file technology designed to allow you to go from canal location to full rotary shaping without

hand filing. The use of this system reduces the number of hand files required down to two, which is for scouting and measurement of the working length with an electronic apex locator. By incorporating a glide path system into my protocol, I am able to take the stress off of me and also reduce the workload of my rotary shaping files by creating a more tapered glide path in comparison to hand instruments. The Traverse system is comprised of a single orifice opener (25/.08 17 mm) and two different-sized glide path shaping files (13/.06 21, 25, 31 mm and 18/.06 21, 25, 31 mm). The files have a triangular cross section for less friction and higher cutting efficiency, and they are treated with variable heat treatment technology to provide incredible flexibility and strength. Flexibility and strength are the two most important factors needed for me to trust in order to incorporate these files into my procedural flow. The files have a noncutting tip to reduce the risk of perforation

Dr. Brett E. Gilbert graduated from the University of Maryland Dental School completing his DDS in 2001 and attaining his Certificate in Endodontics in 2003. He is currently a clinical assistant professor in the Department of Endodontics at the University of IllinoisChicago, College of Dentistry and on staff at Presence Resurrection Medical Center in Chicago. He served as President of the Illinois Association of Endodontists in 2011 and as President of the Northwest Side Branch of the Chicago Dental Society in 2013-2014. Dr. Gilbert was honored by the Seattle Study Club as a Top Ten Young Dental Educator in America in 2017. Dr. Gilbert is board certified, a Diplomate of the American Board of Endodontics. Dr. Gilbert owns and operates a private practice limited to Endodontics in Niles, IL.

and/or ledging of the canal walls transportation. The files have a maximum flute diameter of 1 mm to abide by the principles of dentin conservation. We recognize how important conservation of tooth structure is to keeping the tooth structure strong and more resistant to fracture. When it comes to adopting new technology, I try to be open-minded and ready to advance my protocols. I am always eager to examine and test the waters of the safety, efficiency, and clinical effectiveness the new technology offers. However, I have to truly trust the instrument to bring it into my patient care clinical protocols. I spent a great deal of time testing the Traverse glide path system on extracted teeth to establish this trust. Today, I am using this system in all of my cases, and I have reduced the wear and tear on my body by eliminating almost all hand filing in my procedures. In doing so, I am also creating a more efficient glide path shape that also takes the stress off of my rotary shaping files, allowing me to practice under less stress and with greater efficiency. After using the Traverse system in my procedures for several months, it now has a rightful place in my sponge and is allowing me to provide better treatment to my patients. EP This information was provided by KaVo Kerr.

40 Endodontic practice

Volume 12 Number 3

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PRODUCT PROFILE

Avalon Biomed Industry-leading bioceramics focused on serving endodontists and saving teeth

hen Avalon Biomed Inc. was acquired by NuSmile® Ltd. in late 2016, it was a coming together of two technology leaders with a shared passion for taking both an evidence-based approach to saving teeth and a “high touch” approach to customer care. NuSmile’s Avalon Biomed develops and manufactures industry-leading bioceramic dental materials, including NeoMTA Plus®. This versatile, radiopaque MTA (tricalcium silicate bioceramic) is universally indicated for vital pulp and periapical tissue contact for root canal sealing, root-end filling, resorption treatment, perforation repair, obturation, pulp-capping, base/liner, apexification, and pulpotomy. When NeoMTA Plus cement sets, its matrix will contain calcium hydroxide. Its bioactivity forms hydroxyapatite in situ on its surface, which leads to dentinal bridging, or cementum reformation, as part of the healing process after a pulpal or endodontic procedure. NeoMTA Plus delivers biocompatibility, radiopacity, and superb clinical handling, along with a putty-like consistency, faster setting times, and washout resistance. Moreover, unlike other MTAs, NeoMTA Plus doesn’t stain the tooth, and it is significantly lower-priced. Named the “Top Endodontic Reparative Cement” for 5 consecutive years by THE DENTAL ADVISOR, NeoMTA Plus truly is the new standard for MTA. Veteran NuSmile executive and Avalon Biomed President Mark Binford says Avalon

42 Endodontic practice

Avalon Biomed and its parent NuSmile® Ltd. share a passion for taking both an evidence-based approach to saving teeth and a “high touch” approach to customer care. Biomed has been the perfect fit for NuSmile Ltd., the world leader in esthetic pediatric crowns for over 28 years. “Bringing Avalon Biomed into the NuSmile fold has gone even better than we had hoped,” he said, “and a big reason is that both companies have always been laser-focused on quality, innovation, customers, and outstanding value.” Both companies are also passionate fans of bioactive bioceramic technology. Dr. Carolyn Primus, Avalon Biomed founder and NuSmile Director of Product Development, said, “When a dental procedure isn’t performed using optimal materials, a cascading effect of reparative procedures may occur that further compromises a tooth. By using bioceramic materials in pulpal and other endodontic procedures, you can prevent or slow the downward cascade to tooth loss.” Under Mr. Binford’s leadership, the company has several new bioceramic products in the pipeline for endodontic and pediatric indications, but he isn’t showing his hand yet. “I wish I could say more, but I

can assure you that they will deliver the same blend of performance and value that Avalon Biomed and NuSmile are renowned for,” he said. “We’ve just scratched the surface in our mission to offer the best bioceramic dental materials. We’re confident that these new products will become the industry standard for endodontists, pediatric dentists, and general dentists.” According to Mr. Binford, “Just as with any other highly specialized business, building a great reputation by offering the best service, the best scientifically proven materials, and outstanding value is a sure way for a dental practice to build customer loyalty and referrals.” Mr. Binford and Dr. Primus are determined that Avalon Biomed provides all these to its customers so they have no shortage of new patients, which seems like a great way to ensure that Avalon Biomed has no shortage of new customers. EP This information was provided by Avalon Biomed.

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PRACTICE DEVELOPMENT

Five ways to improve endodontic practice efficiency Dr. Roger P. Levin offers some tips to reduce stress and increase profitability Question: How can endodontic practices increase efficiency to compensate for the lower level of delegation potential in the endodontic practice model? Answer: Endodontic practices are faced with a myriad of challenges. Itâ&#x20AC;&#x2122;s true that they typically experience a high volume of cases (including many emergencies) that create high practice production and profitability; however, they also create chaotic scheduling, unpredictable appointment times, and high levels of stress. And while other specialties such as orthodontics can count on a well-trained assistant to help perform orthodontic treatment, endodontic staff members cannot assume endodontic treatment responsibilities. This lack of delegation opportunity contributes to endodontic practice revenue flattening out at a much earlier rate than other specialty practices. Todayâ&#x20AC;&#x2122;s endodontic practices are also challenged by competitive factors that did not exist even 10 years ago. General dentists are providing more endodontic services; more DSOs that perform root canal services are emerging; and dental implants are becoming a more trusted solution for certain issues that had required endodontic treatment previously. All of these factors necessitate a new look at endodontic practice efficiency. Although delegation will still be limited, maximizing practice efficiency is a smart strategy in helping to maintain and increase patient volume. The following five ways to improve efficiency will be beneficial to many endodontic practices.

1. Design a schedule that meets daily goals. Every endodontic practice should establish a daily goal that adds up to an annual production goal. For example, an endodontic practice could schedule four patients in advance at an average of $1,500 per patient.

You could then expect to have four other patients at an average of $1,200 per patient. This simple hypothetical formula will allow the practice to hit a daily goal of $10,800 per day. Another practice may want to schedule six patients per day at an average of $1,300 per patient, leaving additional time for multichair scheduling to also accommodate emergencies at an average of $900 a day with at least 50% of the emergency root canals being completed in one appointment. Choose whatâ&#x20AC;&#x2122;s best for your practice based on the number of patients that can be pre-scheduled for services, average number of emergencies per day, average production for all of these cases, and any other contingent factors. Then plan to ensure that the practice hits the daily goal (plus or minus 10%) approximately 9 days out of 10.

2. Endodontists should use two or three chairs at a time. This works particularly well when there is one assistant per chair managing each patient and performing all legally acceptable clinical parameters within the practice. Use procedural time study analysis to determine how long the average patient will be in a chair if the practice uses two or three chairs. Every few years an endodontic practice should update the procedural time study. Simply saving 10 minutes per hour in an endodontic practice that is open 4 days per week will result in the equivalent of almost 2 extra months per year of doctor production time. This means that every 6 years, the practice picks up the equivalent of 1 extra year of production time. Think about what this would mean over a 35- or 40-year career.

3. Endodontic assistants should be fully trained with scripting to explain endodontic procedures. A well-trained endodontic assistant communicates effectively and efficiently with patients, saving the doctor a great deal of

Roger P. Levin, DDS, is the CEO of Levin Group, a leading endodontic management consulting firm. Founded in 1985, Levin Group has worked with over 30,000 dental practices. Dr. Levin is one of the most sought-after speakers in dentistry and is a leading authority on endo practice success and sustainable growth. Through extensive research and cutting-edge innovation, Dr. Levin is a recognized expert on propelling practices into the top 10%. He has authored 65 books and over 4,000 articles on dental practice management and marketing. To contact Dr. Levin, visit www.levingroup.com or email rlevin@levingroup.com.

44 Endodontic practice

time by already providing a thorough explanation and answering preliminary questions before the doctor comes in to see them. This in no way diminishes customer service. There are many practices where the staff handles a large portion of communication, and patient reviews are excellent.

4. Endodontic practices should measure the current rate of oneappointment versus multipleappointment root canals. There are endodontic practices that have 20% to 30% of their root canals completed in two appointments. The goal should be for 90% of root canals to be completed in one appointment. Multiple-appointment root canals require more time and overhead. Many endodontic practices end up providing a larger percentage of multiple-appointment root canals simply to manage scheduling inefficiencies resulting from the unpredictability of emergency referrals.

5. One assistant per chair will increase endodontic practice efficiency. There are practices that have added the policy of one assistant per chair with tremendous results. Data clearly indicates that by using this model practices can experience 50% to 100% growth. Although it may appear at times that the assistant is merely babysitting a patient, this approach works because the assistant runs the doctor. The endodontic assistant should have complete command of the clinical area and advise the doctor on where to be at all times based on communication with other assistants and overall management of the patient schedule and clinical procedures. Endodontists will find that having the assistants make the majority of administrative decisions in the clinical area results in very low stress levels, high levels of efficiency, and highly productive endodontic practices.

Summary High demand and unpredictable emergency referrals contribute to inefficiencies in the endodontic practice. There are excellent opportunities today to create much higher levels of efficiency and lower levels of stress when the concepts outlined above are applied. EP Volume 12 Number 3

Dr. Freddy Belliard discusses the use of Vista Dental’s products in developing a predictable irrigation regimen

he goal of root canal cleaning and shaping is the removal of vital or necrotic tissue, microorganisms, and their byproducts while providing space for placing obturation material. The ultimate goal is the complete removal and disinfection of the endodontic space. The tools used in mechanical enlargement of the root canal space are limited in their ability to conform to the intricate root canal anatomy. It has been shown that conventional instrumentation leaves as much as 35% of the canal anatomy untouched. Instrumentation and irrigation, although important factors in canal disinfection, cannot in themselves be relied upon for optimal canal cleanliness. As the market trends toward techniques requiring fewer instruments, these techniques have had a negative impact and consequence of less associated irrigation, which has impacted endodontic retreatment rates. Acoustic streaming and cavitation have been proven to significantly enhance cleaning of difficult anatomy. When ultrasonic activation is introduced, irrigant streaming and cavitation occur, resulting in significantly improved debridement of canal spaces, disruption of biofilm, and improved penetration of irrigants into dentinal tubules. The ultrasonic activation of irrigants greatly reduces bacteria levels, ultimately improving the prognosis and ability to seal. EndoUltra® is the first and so far only cordless activation device available. Not tethered to a wall or machine, the cordless device is easily incorporated into one’s existing irrigation protocol. Incorporating this product as well as enhanced irrigants into irrigation protocol is an effective, predictable method of improving endodontic care. Enhanced irrigants paired with ultrasonic activation are key to thoroughly cleansing canal anatomy. Freddy Belliard, DDS, specializes in microendodontics in Guadalajara, Spain, and is also the Co-Chairman of RootsSummit 2020 in Prague, Czech Republic.

Volume 12 Number 3

Vista Dental’s irrigation products offer you the ability to simplify the irrigation process and therefore more predictably achieve endodontic success. Vista Dental’s patented solutions, Chlor-XTRA™ and SmearOFF™ 2-in-1, are great options when developing a predictable irrigation regimen. Chlor-XTRA™ is an enhanced NaOCl. Proprietary chemistry gives this 6% NaOCl a lower surface tension, allowing for improved penetration into canal anatomy and significantly faster tissue dissolution compared to standard NaOCl. SmearOFF™ is an EDTA-based formula enhanced with chlorhexidine. SmearOFF™ not only effectively removes the smear layer but also kills bacteria in one easy step. Unlike

other 2-in-1 mixes, SmearOFF™ is compatible with sodium hypochlorite and will not form a precipitate — eliminating steps and saving time with each procedure. Vista Dental’s irrigation products offer you the ability to simplify the irrigation process and therefore more predictably achieve endodontic success. For more information, call Vista Dental Products at 877-418-4782, or visit www. vista-dental.com. EP

This information was provided by Vista Dental Products.

Endodontic practice 45

PRODUCT PROFILE

The importance of ultrasonic irrigation in modern endodontics

SMALL TALK

Weathering the storms of leadership Drs. Joel C. Small and Edwin McDonald discuss how a seasoned leader can create a balance

leader brings the “weather” to the organization that he/she leads, be it large or small. The weather can range from stormy and turbulent to sunny and full of the sun’s energy. A weather that supports healthy, growing lives requires a balance of rain, sun, and the seasonal variations that allow for a complete cycle of life. What kind of weather do we find when the leader is not leading?

A practice in survival mode For all forms of life to be healthy, including human beings, they need the right mix of elements to breathe life into them. Effective, purpose-driven leadership cannot exist without these essential ingredients that create a healthy environment. The first sign that a leader is not leading is that the individuals under their leadership are not thriving; in fact, they are struggling to survive. The most significant leadership competency that correlates with high levels of organizational performance is strong people skills. Those skills pertain more to the leader being personable, approachable, and a good listener rather than possessing a dynamic personality. All people need to be heard and understood and, equally important, need a positive and safe environment that encourages open and direct dialogue. When leadership is deficient, the people’s need to be heard and to have a voice is absent. Their relationship with the leader is superficial and lacks the depth that people need to commit to the organization’s purpose. Their low-level

Drs. Joel Small and Edwin (Mac) McDonald have a total of over 75 years of dental practice experience. Both doctors are trained and certified Executive Leadership Coaches. They have joined forces to create Line of Sight Coaching, a business dedicated to helping their fellow dentists discover a better and more enjoyable way to create and lead a highly productive clinical dental practice. Through their work, clients experience a better work/ life balance, find more joy in their work, and develop a strong practice culture and brand that positively impact their bottom line. To receive their free ebook, 7 Surprising Steps to Grow Your Practice Through Leadership, go to www.lineofsightcoaching.com.

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motivation and commitment reflect an organizational culture that is transactional rather than transformational in nature. Symptoms: high staff turnover, internal conflict, low productivity

defines an enterprise that is stuck and performing below its capability. Symptoms: low productivity, wasted energy, confusion, conflict

Lack of clarity, purpose, and vision

By definition, a team comes together to accomplish something as a group that they could not do by themselves. Each team member has a specific role and responsibility. An effective leader orchestrates the function of the overall team as well as each individual. These leaders communicate the importance of each position and what success looks like. In short, they are great people developers and intentionally empower those that they lead. It is not uncommon, as coaches, to encounter doctors who are seeking a better work/life balance. They are exhausted by the persistent conflict between family and practice — feeling caught between the constant pull of the practice on their purse strings and the opposing pull of their family on their heartstrings. Invariably, these doctors have failed to develop their teams’ capacity to lessen the doctors’ load. These doctors have not provided their staff with the training, resources, and authority to manage and oversee practice systems. Sadly, these doctors have done a great disservice to themselves and their staff. The doctors are

Great leaders bring clarity, establish values, and articulate vision. There exists a commonly shared belief and understanding about where the leader is taking the organization. The team understands the organizational values, and therefore, they know how to make decisions in alignment with the shared purpose. This creates an entire team of decision-makers and energy producers that are working toward the same goal. In this ideal scenario, the doctor is no longer the “bottleneck” through which all decisions emanate. This allows the overall team to develop their capabilities and capacity to be more productive. When clarity, values, and vision are missing, there is greater confusion, more hesitation to act, and more internal conflict. This inevitably results in organizational stagnation. Stagnant teams find themselves spending excessive energy maintaining the status quo, rather than taking necessary measures and calculated risks designed to promote practice growth. This description

Exhaustion

Volume 12 Number 3

Lack of trust The “currency” of relationships is trust. Trusting relationships are the building blocks of a successful contemporary practice. Highly effective leaders understand this and have spent a great deal of time and effort on the inner game of personal development to become more trusting and trustworthy leaders. Most successful practices have leaders and teams that trust one another. They trust in one another’s integrity and capability. Exceptional leaders understand that trust is established through both words and actions. They not only believe in their people, but also speak and act in a manner consistent with this belief. In contrast, underdeveloped leaders cancel out their personal strengths and erode trust with words and behaviors that are grounded in distorted beliefs and assumptions. Let’s use exhausted doctors mentioned earlier as an example. These doctors may be high achievers, but when we look at their team dynamics, it is obvious that they are not utilizing the staff’s capabilities to achieve their goals. These doctors may be harboring the false assumption that they do not need the team’s input or skill to accomplish their goals. The doctors may even believe that their team is incapable of carrying out the more intricate tasks necessary to achieve highpriority goals. Given this false assumption, the doctors may then adopt a self-limiting belief that only they can do the work necessary to accomplish these goals. Thus, these doctors see no value in developing the team — choosing to “go it alone” and isolating themselves — forgoing valuable collaboration and assistance that would lighten the load, allowing for a better work/life balance, and resolving their state of exhaustion. Through the doctor’s words and actions, the team members sense that the doctor lacks confidence in their abilities. They see that the doctor does not value their thoughts or efforts. They feel the obvious lack of trust, and from that point on, dialogue breaks down, creativity and collaboration cease to exist, and stagnation arises. In the absence Volume 12 Number 3

A weather that supports healthy, growing lives requires a balance of rain, sun, and the seasonal variations that allow for a complete cycle of life. of trust, team members will fail to make the commitments that will unlock their potential. Trust will also erode when default leadership results in ill-defined practice values and purpose. Because there is no clarity, there is also no shared understanding of the direction of the practice. Team members, lacking this sense of common values and purpose, are left to define their own values and create their own interpretation of the organization’s purpose. In effect, each team member begins to act out of his/her own self-defined operating system. There is no common driving force within the organization, and dysfunction ensues. Dysfunction is accompanied by distrust as each team member views the other team members’ actions in conflict with his/her own selfdefined organizational values and purpose. Symptoms: conflict, disillusionment, high turnover, lack of team coordination, low production and organizational capacity

Burnout Burnout is different from exhaustion. Exhaustion is the loss of physical stamina due to an excessive workload. Burnout is the loss of passion as well as physical and emotional stamina created by a heavy workload without the benefit of personal development. Recent workforce research has shown personal development to be the secret potion that can prevent burnout. This applies to both the doctor and staff. Along with personal growth come energy, passion, and an interest to continue growing and succeeding. We have found that the most successful healthcare practices expend significant resources in the development of their people. These are the same practices that serve as icons in our industry. With ineffective leadership and an underdeveloped staff, the practice must work harder to compensate for these deficiencies. Often the best people burn out and will eventually leave the practice in search of something more enjoyable and rewarding — a practice that is willing to invest in their personal development. Unfortunately, this

leaves the less qualified team members to carry the load, which soon becomes very heavy and unsustainable. When it becomes obvious that the problems are not solvable through more work, exhaustion, burnout, and poor work/life balance become the unavoidable consequences. If these conditions persist long enough, then disillusionment, anxiety, and depression are the unfortunate outcomes. Symptoms: exhaustion, loss of passion, widespread practice decline, turnover, disillusionment, anxiety, depression

Summary In summary, all the major stress producers that dentists report — managing their team, inadequate income, lack of meaningful work, navigating a complex marketplace — have their basis and their solution around the leader’s competencies. Most dental practice owners are looking for solutions in the latest technology, business management systems, clinical training, and marketing. Without a doubt, these assets are important parts of a comprehensive strategy for success. However, their impact on the practice will have a ceiling that is determined by the level of leadership provided by the doctor. Business performance is directly correlated with the level of leadership operating within the organization. The research and case studies completed over the past 30 years consistently reveal this. There is hope, however. Extensive research into leadership development has resulted in new tools and highly reliable assessments that pinpoint a potential leader’s generative/creative competencies that enhance leadership effectiveness as well as those reactive tendencies that inhibit his/ her leadership capabilities. Armed with this vital information, individualized leadership development programs are now designed for doctors by trained professional coaches. Furthermore, new and creative ways of assessing the efficacy of these individualized leadership development programs are now available and are widely employed in the development process. We now know that great leaders are not born; they are made. Sometimes they are made out of a crisis or adversity. Sometimes leaders are made intentionally by someone who wants to experience a better life. That someone could be you. That journey could begin today. All it takes is an awareness of the importance of leadership and the commitment to develop those skills. There are more resources to guide you now than ever before. It is up to you. EP Endodontic practice 47

SMALL TALK

exhausted, and their staff has lost an opportunity to experience growth. Even worse, these doctors find that they are spending an inordinate amount of time and energy on lowlevel tasks rather than value-producing tasks that greatly benefit the practice — tasks that only they can accomplish. Symptoms: lack of energy, failure to achieve high-priority goals, undeveloped staff, strained interpersonal relationships, reduced production

BOOK REVIEW

Microsurgical Endodontics Augmented reality in microsurgical endodontics: the future of endodontic treatment

ndodontic specialists Bertrand Khayat, DDS, MSD, and Guillaume Jouanny, DDS, first met in the classroom while Dr. Jouanny was an undergraduate student in Dr. Khayat’s class. What began as a mentorship forged over deep commitment to the profession soon blossomed into a decade-long collaboration between the two clinicians, surgeons, and lecturers. Recently, they have combined their knowledge into the textbook Microsurgical Endodontics (Quintessence Publishing, 2019). “This book is designed to help every practitioner, general dentist, and endodontist to perform endodontic microsurgery,” they say. “Every step is described in detail from the anesthesia to the sutures, and special emphasis has been placed on the clinical aspect of the procedure with plentiful illustrations and clinical examples. This book can be used as a reference for simple as well as for more complex indications.” Microsurgical Endodontics brings to light the use of endodontic surgery as a reliable, high-success treatment solution that,

Dr. Bertrand Khayat

Dr. Guillaume Jouanny

until now, has too often been overlooked. Given the breakthroughs in recent years, endodontic surgery has advanced to the point where it rivals conventional practices. In this book, endodontic surgery is finally being appreciated for its effectiveness as a treatment option, especially when conventional retreatment is not ideal. “Microsurgical endodontics is not an apical resection anymore,” the authors explain. “The use of the operating microscope, the evolution of the ultrasonic tip, and new materials allow for a better prognosis. It is now possible to perform endodontic

Microsurgical Endodontics incorporates the use of augmented reality through an app, so readers can access supplementary videos that bring select images in the book to life Sarah (Natale) Mondello is a book-publishing professional in the Chicago area. As the Marketing Editor at Quintessence Publishing, she maintains dual book editing and marketing strategy duties, including writing blog articles and designing graphics for print and digital use. She is a recent summa cum laude graduate of Drake University, where she studied writing, public relations, and graphic design. Mondello is also a published novelist and frequently speaks about the writing, editing, publishing, and promotion stages of book publishing.

surgeries with a success rate of more than 90%. In the peri-implantitis era, it is obvious that mastering endodontic surgery will be a great asset to save more teeth.” To reinforce the material presented, Microsurgical Endodontics takes QR codes to the next level by incorporating the use of augmented reality, thereby providing readers with an enhanced visual experience. Readers can download an app for iOS or Android that allows them to access videos handpicked by the authors. These supplementary videos bring select images in the book to life by simply hovering a smart device over each image. “The augmented reality feature is a new step in education,” the authors say. “It is now possible to precisely visualize the gestures explained in writing. Different key movements with a blade, an elevator, or an ultrasonic tip are shown in short videos so that the reader better understands how to perform the procedure.” This enriched reading experience is just one part of the authors’ vision for the book and the successes in endodontic treatment they anticipate resulting from its use. “Our goal is that every dentist understands the wide range of indication of endodontic surgery,” the authors emphasize. “We hope that students, general dentists, and experienced specialists will find relevant information and that this book will help our colleagues take a step further in endodontics and start to include endodontic microsurgery in their daily practices.” To learn more about Microsurgical Endodontics, visit www.quintpub.com. EP Review by Sarah Mondello

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Volume 12 Number 3

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

Attending the ADA FDI World Dental Congress 2019? Tour the advanced technology of ZEISS EXTARO 300. September 5-7, 2019 | ZEISS Booth 6356 SUR.11393 Rev B ©2019 Carl Zeiss Meditec, Inc. All rights reserved.

So smart,

so simple. Introducing the CS 9600 scanner for endodontists. There’s nothing simple about endodontic treatment. But now there is a simpler way for your staff to capture the high-quality images you need to achieve faster diagnoses and treatment plans. Learn more about this simply brilliant scanning solution at carestreamdental.com/CS9600.

CS 9600