Endodontic Practice US Spring 2020 Vol 13 No 1

clinical articles • management advice • practice profiles • technology reviews

A clinical case of a necrotic UR6 associated with periapical periodontitis Dr. John Rhodes

Treatment of maxillary first premolars with three root canals (case report) Drs. Yuriy Riznyk, Svitlana Riznyk, and Khrystyna Sydorak

Educator profile Dr. L. Stephen Buchanan

Clinician-centered assessment of 3D-printed stents for Targeted Endodontic Microsurgery (TEMS) Drs. Julie A. Anderson, James A. Wealleans, and Jarom J. Ray

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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 2020. 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.

“It’s easier to ask forgiveness than it is to get permission”

O

ur specialty of endodontics has evolved, and continues to evolve, through the application of emerging technologies.

As you reflect on the experiential process of adopting microscopes and CBCT into your clinical practice, were you late to the game or an early adopter? What has been your level of consideration to use new calcium-silicate sealers based on nanoparticles or applying advanced fluid dynamics and multisonic energy to remove biofilm and dissolve pulpal tissue?

In a recent podcast, nephrologist Dr. Jason Fung discussed Evidence-Informed Medicine and using ethical judgment in deciding to bring new concepts to your patient care. EvidenceBased Medicine remains the bedrock of our clinical decision Scott K. Hetz, DMD process, but he said that sometimes it feels like less of a search for the truth and more like a search for consensus.

We’ve all heard the clever quip in the title above about whether or not to ask for permission before going “experimental,” but where does it come from? Google it, and you will find reference after reference crediting Grace Hopper — a U.S. Navy Rear Admiral and pioneering computer scientist — as the author.

Grace Hopper earned both her Master’s in Mathematics and Physics and her Ph.D. in Mathematics from Yale University by 1934, and then joined the Navy Reserves, where she worked on the military’s Mark I proto-computer project at Harvard during World War II. Her close relationship with the U.S. military and the early computer industry shaped Hopper’s career during a time when women weren’t widely accepted as leaders in academics or as military officers. In spite of that, she excelled in these male-dominated arenas.

In 1952, Hopper changed the computer industry when her programming team developed the first computer language “compiler,” making it possible to write programs for multiple computers rather than just a single machine. Her team then developed Flow-Matic, the first programming language to use English-like commands. And by 1959, these innovative contributions led Hopper to become a co-inventor of the Bomarc system, later called COBOL (Common-Business-Oriented Language).

Her biographer, Kurt Beyer, called her “the person most responsible for the success of COBOL during the 1960s.” Her life’s work was significant — by the 1970s, it was the most extensively used computer language in the world. Without a doubt, Rear Admiral Grace Hopper earned her nicknames: “Amazing Grace” and “Grandma COBOL.” She remained active after retiring from the Navy and became an iconic mentor to future leaders of the computer industry — often speaking at engineering forums and universities — passing on the value of adopting new technologies. She was a leader in the best sense of the word, as exemplified by her oft-stated opinion that “the most damaging phrase in our language is, ‘We’ve always done it this way.’”

Each of us has the opportunity to be an active participant in the direction of our own practice of endodontics. The next time you make that conscious decision to embrace a new intellection, just smile to yourself and think of “Amazing Grace,” a woman who was a legend in her own time. Like it or not, change is inevitable, and new technology options will continue to evolve, so don’t apologize seizing those opportunities that will propel you forward, even though “It’s easier to ask forgiveness than it is to get permission.”

Scott K. Hetz, DMD, is a 1997 graduate of the University of Pittsburgh School of Dental Medicine. Dr. Hetz served in the United States Air Force for 9 years, including an Advanced Education in General Dentistry program. Also, while on active duty, he received his specialty Certificate in Endodontics from the University of Southern California in 2004. Dr. Hetz is a Diplomate of the American Board of Endodontics, member of the Endodontic College of Diplomates, and Specialist Member of the American Association of Endodontists and District of Columbia Dental Society. He volunteers as Affiliate Faculty in the Department of Endodontics Naval Postgraduate Dental School at Walter Reed National Military Medical Center. Dr. Hetz maintains a full-time practice as a partner with Advanced Endodontic Associates in Washington, D.C. He can be reached at scotthetz@mac.com.

ISSN number 2372-6245

Volume 13 Number 1

Endodontic practice 1

INTRODUCTION

Spring 2020 - Volume 13 Number 1

TABLE OF CONTENTS

Publisher’s perspective Resolution or resolve? Time to take positive action in 2020!

Lisa Moler, Founder/CEO, MedMark Media................................ 6

Endodontic perspective

Educator profile L. Stephen Buchanan, DDS

8

The Pendulum Swings Dr. John West discusses “Minimally Invasive” versus “Maximally Appropriate”.................................... 17

Clinical Management of a large external inflammatory root resorption

Sharing competency

Drs. Renato Piai Pereira, Murilo Priori Alcalde, Rodrigo Ricci Vivan, Marco Antonio Hungaro Duarte, Rogério Vieira Silva, and Clóvis Monteiro Bramante describe the therapeutic approach for a case of inflammatory external root resorption....................20

Clinical research Efficacy of different procedures in removing radiopaque organic material from simulated internal root resorption cavities: an ex vivo study

Clinical research

10

Clinician-centered assessment of 3D-printed stents for Targeted Endodontic Microsurgery (TEMS) Drs. Julie A. Anderson, James A. Wealleans, and Jarom J. Ray discuss safe and effective 3D printing to produce surgical stents

2 Endodontic practice

Drs. Claudia Hernández Restrepo, Gonzalo García, Denise Alfie, Sharon R. Oyhanart, and Fernando Goldberg discuss removing organic material from simulated internal resorption cavities............................................24

Volume 13 Number 1

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TABLE OF CONTENTS Technology Adaptive core instruments — perfect for retreatment Drs. Martin Trope, Klaus Lauterbach, and Gilberto Debelian discuss how these files clean the canal in all dimensions with minimal removal of dentin..........................................28

Industry news .......................................................32

Continuing education Treatment of maxillary first premolars with three root canals (case report) Drs. Yuriy Riznyk, Svitlana Riznyk, and Khrystyna Sydorak discuss how modern instrumentation can make it more viable to tackle rare and complex root canal systems..........................36

Practice management Why, when, and how to raise your fees Dr. Albert Goerig discusses the fee schedule equation and your practice’s profitability.......................................40

Continuing education

33

A clinical case of a necrotic UR6 associated with periapical periodontitis

Dr. John Rhodes demonstrates a methodical approach using reciprocating nickel-titanium instruments

Product profile

Service profile

ENDOSEAL MTA

Large Practice Sales

Dr. Jeffrey D. Krupp discusses the excellent physical and biological properties of this obturation material .......................................................42

Chip Fichtner explains how it pays to know your practice’s value to a silent partner............................................ 46

Product spotlight Boyd Industries — products specifically for the endodontic market .......................................................44

Small talk The critical element is missing from most leadership assessments Drs. Joel Small and Edwin McDonald discuss an assessment that correlates with leadership effectiveness............ 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

Volume 13 Number 1

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PUBLISHER’S PERSPECTIVE

Resolution or resolve? Time to take positive action in 2020!

T

he New Year is a time for resolutions — which has led me to think of the true meaning of that word. Resolution is defined as “a firm decision not to do something.” That doesn’t sound so positive to me. I am more invested in the word resolve, defined as to “decide firmly on a course of action.”

That’s more like it! As leader of the MedMark team, our vision and our goals for 2020 are positive — we don’t want to “not do something”; we are going to take action on many exciting innovative, creative projects for our readers and advertisers.

This year, on our media side, we continue to inform and educate through DocTalk videos and podcasts. For clinicians involved with dental sleep medicine, our new ZZZ Pack Podcast will bring news and views from some of the most Lisa Moler Founder/Publisher, MedMark Media knowledgeable sleep-focused dentists in the niche. Also, Dr. Rich Mounce will feature many of our most popular authors on his Dental Clinical Companion Podcast. In the past few years, I have been fortunate to help motivate our audience by interviewing some phenomenally inspiring people — Shaquille O’Neal, Tony Robbins, Simon Sinek, and Dr. Oz, and I will continue to connect you with those who can encourage you to expand your horizons.

Our print and digital articles continue to keep you on the cutting edge of clinical and practice management ideas and information. In our CEs, Dr. Yuriy Riznyk, et al., tackles rare and complex root canal systems with modern instrumentation, and Dr. John Rhodes illustrates his successful negotiation of challenging sclerosed canals in a maxillary molar. Dr. Julie Anderson and colleagues discuss safe and effective 3D printing to produce surgical stents — these authors are involved with the U.S. Air Force, and we are proud to welcome them to our publication. Dr. Martin Trope and colleagues discuss cleaning canals with minimal dentin removal, and Dr. John West explains minimally invasive endodontics in a maximally appropriate way. In the Practice Management column, Dr. Albert Goerig discusses your practice’s profitability and why, when, and how to raise your fees.

2020 has just started, and the opportunities to expand your practice potential are endless!

Along with our constant resolve to inform you through the written word of the most current technologies, products, services, and techniques, keep watching for us online and in person at major dental meetings and events across the United States. Please continue to contact us with your article ideas or if you want to take part in one of our online chats or podcasts. This year, “resolve” along with us to “embrace the exceptional.” Start the decade as we have — deciding firmly on a course of positive action based on solid science, facts, and innovation.

To your best success in 2020!

Lisa Moler Founder/Publisher MedMark Media

Published by

PUBLISHER Lisa Moler lmoler@medmarkmedia.com DIRECTOR OF OPERATIONS Don Gardner don@medmarkmedia.com MANAGING EDITOR Mali Schantz-Feld, MA mali@medmarkmedia.com | Tel: (727) 515-5118 ASSISTANT EDITOR Elizabeth Romanek betty@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 & DIGITAL STRATEGY Amzi Koury amzi@medmarkmedia.com EMEDIA COORDINATOR Michelle Britzius emedia@medmarkmedia.com SOCIAL MEDIA & PR MANAGER April Gutierrez medmarkmedia@medmarkmedia.com FRONT OFFICE ADMINISTRATOR Melissa Minnick melissa@medmarkmedia.com

MedMark, LLC 15720 N. Greenway-Hayden Loop #9 Scottsdale, AZ 85260 Tel: (480) 621-8955 | Fax: (480) 629-4002 Toll-free: (866) 579-9496 www.endopracticeus.com www.medmarkmedia.com

SUBSCRIPTION RATES 1 year (4 issues) $129 | 3 years (12 issues) $349 Subscribe at www.medmarksubscriptions.com

6 Endodontic practice

Volume 13 Number 1

Courtesy of Allen Ali Nasseh, DDS, MMSc

BY YOUR SIDE

Visit our website at BrasselerUSA.com To order call 800.841.4522 or fax 888.610.1937. In Canada call 800.363.3838.

Invoice or statement prices may reflect or be subjected to a bundled discount or rebate pursuant to purchase offer, promotion, or discount program. You must fully and accurately report to Medicare, Medicaid, Tricare and/or any other federal or State program, upon request by such program, the discounted price(s) or net price(s) for each invoiced item, after giving effect to any applicable discounts or rebates, which price(s) may differ from the extended prices set forth on your invoice. Accordingly, you should retain your invoice and all relevant information for your records. It is your responsibility to review any agreements or other documents, including offers or promotions, applicable to the invoiced products/prices to determine if your purchase(s) are subject to a bundled discount or rebate. Any such discounts must be calculated pursuant to the terms of the applicable purchase offer, promotion, or discount program. Participation in a promotional discount program is only permissible in accordance with discount program rules. By participation in such program, you agree that, to your knowledge, your practice complies with the discount program requirements.

Š2020 Brasseler USA. All rights reserved.

B-5178-EP-03.20

EDUCATOR PROFILE

L. Stephen Buchanan, DDS Sharing competency What can you tell us about your background?

I have documented Attention Deficit Disorder, so I love doing dangerous things safely in human beings, and I am afraid I might go to hell if I bore my students as I have been bored so often in my education.

What originally attracted you to the specialty of endodontics?

The anatomy of root canal systems and the technical challenges of treating them.

Being an endodontist is awesome because patients’ expectations are really low — if I can avoid hurting them, they love me.

Plastic surgeons have a much tougher job because they have to make ugly people look good.

What aspect of your training inspired you to add educator to your list of accomplishments?

I wanted dental colleagues to have as much fun as I do performing RCT.

What are your proudest moments in the clinical and teaching aspects of your life?

L. Stephen Buchanan, DDS

Graduating first in my dental school class; inventing variably tapered RCT files, a 2-second method of 3D obturation; 3D-printed training replicas and a hands-free irrigating system; broadcasting live-patient RCT demonstrations over the Internet with 1,680 real-time viewers from around the world.

What do you think is unique about your teaching methods?

I teach to share competency, not to feed my ego.

As an educator, what have you learned from your clinical students?

Many of my best clinical tricks were learned from dentists taking my hands-on 8 Endodontic practice

Dr. Buchanan teaching

courses — also, I have learned that dentists are very smart and caring professionals.

invasive RCT, so teeth are as structurally intact after as before.

What has been your biggest challenge in sharing information and educating dentists about endodontics?

What would you have become, had you not become a dentist?

Explaining complex procedures in the simplest, most effective terms.

What advice would you give to budding endodontists?

Find a place in the middle of the United States to practice; retire early as a result; and then move to California.

What is the future of endodontics?

We will get better at performing minimally

I have no idea. I decided to be a dentist at the age of 16, and I cannot imagine a better job.

What are your hobbies?

Woodworking, stained glass, jewelry design, endodontics.

What do you do in your spare time?

Read biographies, history, economics, and murder mysteries. Spend time doing whatever my lovely wife wants to do. EP Volume 13 Number 1

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CLINICAL RESEARCH

Clinician-centered assessment of 3D-printed stents for Targeted Endodontic Microsurgery (TEMS) Drs. Julie A. Anderson, James A. Wealleans, and Jarom J. Ray discuss safe and effective 3D printing to produce surgical stents TABLE 1. 3D Printers and their associated technical classifications, approximate costs and printer specifications.

Introduction Applications of three-dimensional (3D) printing appear in the endodontic literature for guided access, autotransplantation, and endodontic surgery.1-6 The majority of endodontic publications utilized patented, jetting-type printers such as PolyJet (Stratasys Ltd, Austin, Texas), MultiJet (3D Systems, Rock Hill, South Carolina), or ColorJet (3D Systems, Rock Hill, South Carolina) (Table 1).7 Jetting-type printers extrude thin layers of proprietary photopolymer material onto a build tray where the layers are cured immediately after deposition. Each subsequent layer is deposited upon the previous layer, as the build platform moves downward, away from the extruder.8 These printers have been shown to be highly accurate with minimal postprocessing requirements, but their size and cost may be prohibitive to use in individual endodontic practices.8 Alternative technologies such as stereolithography apparatus (SLA) and digital light processing (DLP) printers have price points and size profiles more amenable to widespread deployment throughout endodontics.9 Both SLA and DLP

Objet 260 Connex 3 (Stratasys Ltd, Austin, TX) Technology

PolyJet

SLA

DLP

$120,000

$3,500

$500

Minimum XY

600 DPI

140 μm

50 μm

16 μm

25 μm

50 μm

Minimum layer thickness

Table 1: 3D Printers and their associated technical classifications, approximate costs, and printer specifications

printers utilize vats of photosensitive resin in which the build platforms are submerged, yet they differ in their methods of curing the resin. SLA employs a focused UV laser to trace the cure locations for the object being printed, whereas DLP utilizes a projector that exposes the entire layer simultaneously.8 In both systems, the platform is raised out of the resin vat as the build is completed from the bottom upwards. The Form 2 (FormLabs Inc, Somerville, Massachusetts) is an SLA

James A. Wealleans, DMD, received his dental degree from Nova Southeastern College of Dental Medicine in Fort Lauderdale, Florida, in 2006. Dr. Wealleans completed an Advanced Education in General Dentistry at the United Sates Air Force Academy in 2007. In 2010, he received a certificate in endodontics from Wilford Hall Medical Center and the University of Texas Health Science Center, San Antonio. Dr. Wealleans is a Diplomate of the American Board of Endodontics. Wealleans served as the deputy program director of the Wilford Hall Endodontic program from 2013-2018. In early 2019, he retired from the U.S. Air Force and moved to Australia. Dr. Wealleans now practices endodontics in the Northern Beaches of Sydney.

Jarom J. Ray, DDS, is the Residency Program Director at the Air Force Postgraduate Dental School and serves as Associate Professor of Endodontics at the Uniformed Services University of the Health Sciences. He received his DDS from Creighton University Medical Center School of Dentistry in 2003 and then completed a 1-year Advanced Education in General Dentistry Residency at the USAF Academy in 2004. In 2008, he received a certificate in endodontics from Wilford Hall Medical Center and achieved Board certification in 2011. Dr. Ray is an inventor of Targeted Endodontic Microsurgery and has lectured nationally and internationally on endodontic applications of 3D printing. His research focuses the intersection of 3D printing and endodontic surgery.

10 Endodontic practice

Duplicator 7v1.4 (Wanhao, Zhejiang, China)

Cost

Julie A. Anderson, DMD, MSc, is a Major in the U.S. Air Force and a practicing endodontist at Hurlburt Air Field, Florida. She received her DMD from University of Kentucky College of Dentistry in 2013 and then completed a 1-year Advanced Education in General Dentistry Residency at Langley Air Force Base, Virginia, in 2014. In 2019, she received a certificate in endodontics from the Air Force Postgraduate Dental School, Lackland Air Force Base, Texas, as well as a Master of Science in Oral Biology from the Uniformed Services University of the Health Sciences. Dr. Anderson is currently pursuing Board certification by the American Board of Endodontics.

Disclosure: The authors deny any conflicts of interest.

Form 2 (FormLabs Inc, Somerville, MA)

printer costing about $3,500. The Duplicator7 (Wanhao, Zhejiang, China) is a DLP printer costing about $500 (Table 1).

Targeted Endodontic Microsurgery (TEMS) uses 3D printing to produce surgical stents capable of guiding a trephine bur according to exacting design specifications.10 A trephine is rotated within the guide port of a stent producing osteotomy, root end resection, and biopsy in a single step. Figure 1 shows surgical access to the palatal root of the maxillary first molar (A), implant-planning software used to define the TEMS pathway for removal of palatal and facial root ends (B), guides designed to seat on the patient’s dentition (C), exacting guidance of a trephine (D), a trephine oriented by a guide seated upon the patient’s dentition (E), a trephine in position for rotation at 900-1,200 revolutions per minute (rpm) (F), osteotomy and root end resection (G,H), en bloc removal of a biopsy specimen (I), palatal soft tissue removal using a rotary biopsy punch (J), soft tissue preserved in Hank’s Balanced Salt Solution (K), trephine resection of the palatal root end (L-N), soft tissue approximated and sutured to serve as a scaffold for healing (O,P,R,T), allowing for treatment of three root ends, (Q) and healing at 1-year recall (S). The surgical guides (3DSGs) used in the introductory TEMS publication were printed with an Objet260 Connex 3 (Stratasys Ltd, Austin, Volume 13 Number 1

Materials and Methods Part I: Dimensional comparison A template with five cylindrical holes of varying diameter was designed using SOLIDWORKS 2018 software. Hole diameters were chosen based on the ISO diameters of a friction grip bur (1.6 mm), a latch-type (2.35 mm), and three trephine burs (4.0 mm, 5.0 mm, and 6.0 mm). The standard tessellation language (STL) file was used to print 30 templates from each of the three printers according to manufacturer’s instructions (Figure 2A). The Objet260 required proprietary MED610 resin (Stratasys Ltd, Austin, Texas). In contrast, the Form 2 and the Duplicator7 could not use Volume 13 Number 1

A.

B.

E.

I.

L.

Q.

CLINICAL RESEARCH

Texas) PolyJet printer costing in excess of $120,000.10 To date there have been no evaluations of jetting-type, SLA, or DLP printers for TEMS or guided endodontic access.

Previous engineering studies have evaluated printer accuracy for endodontic and non-endodontic applications by using a 3D scanner and software to compare the dimensions and volume of a printed part to its virtual design.11-14 These studies provide quantification of the relative conformity of a printer’s product with the original design, but clinical acceptability is not necessarily established, as such studies do not define how much dimensional and volumetric deviation from the digital design will produce a clinically acceptable stent.12 Further, if a printer deviates from design dimensions in a consistent manner, adjustments to design can be made to render print products clinically acceptable.

For example, a printer that consistently prints slightly smaller than the target dimension can be corrected for in the design phase by adjusting dimensions. The same is not true for an inconsistent printer that sometimes prints larger than design dimensions and sometimes smaller.

A gap in knowledge exists in that the clinical acceptability of individual three-dimensional printers (3DPs) for TEMS applications is unknown. The purpose of this study is to quantify conformity between design dimensions and printed objects for the Objet260, Form 2 and Duplicator7 3DPs (Part I), and then to conduct a clinically oriented assessment of the acceptability of TEMS stents produced by each of these printers (Part II).

For Part I, the null hypothesis was that printed objects from all printers will precisely conform to digital design dimensions. For Part II, the null hypothesis was that all 3DSGs from the three printers will be clinically acceptable in this simulation model.

D.

C.

F.

G.

H.

K.

J.

M.

N.

R.

O.

S.

P.

T.

Figures 1A-1T: 1A. Tooth No. 3 demonstrating radiolucencies on all three roots. 1B. TEMS pathway. 1C. 3DSG design. 1D. Palatal 3DSG. 1E. MB 3DSG. 1F.Trephine rotation. 1G. MF osteotomy; DF core removed. 1H. MF core elevation. 1I. Facial resections (top), cores after elevation (bottom), separated instrument (arrow). 1J. Punch removal of mucosa. 1K. Tissue stored in Hank’s balanced salt solution. 1L. Palatal 3DSG in position. 1M. Removal of palatal core. 1N. Palatal core. 1O. Replanted palatal mucosa prior to suturing. 1P. Palatal tissue sutured, coated with cyanoacrylate tissue adhesive. 1Q. Immediate postoperative radiograph. 1R. One week postoperative. 1S and 1T. 8-month recall radiographic/clinical healing

MED610, and so templates were printed with NextDent SG Resin (3D Systems, Soesterberg, Netherlands). Templates were post-processed according to manufacturer’s instructions and then scanned by a benchtop scanner (3Shape D1000; Whip Mix Corp, Louisville, Kentucky). GeoMagic Studio 2014 software was used to measure

the diameters of the printed templates as in previous accuracy studies (Figure 2B).11-13,15 For all 150 cylindrical holes, the absolute difference between the printed diameter, as measured using GeoMagic Studio, and the virtual diameter, as input into SOLIDWORKS during the design phase, was measured, and the data was subjected to a univariate Endodontic practice 11

CLINICAL RESEARCH analysis of variance (ANOVA) and post-hoc Tukey’s test.

Part II: Clinically oriented assessment of TEMS stents The entire digital workflow, 3D printing, and post-printing quality evaluation of the experimental model and 3DSGs were conducted by a consensus group comprised of two Board-certified endodontists, an endodontic resident, a biomedical engineer, and a medical CAD/CAM design specialist.

Experimental printed cast: Based upon accuracy data from Part I, the Objet260 was used to print the experimental model utilized during Part II. The original anonymized CBCT and STL files from Case 1 of the introductory TEMS publication for palatal root surgery of tooth No. 2 were used to print a maxillary model.10 The CBCT region of interest for the experimental model included the entire maxillary dental arch, hard palate, floor of the nose, and most of the maxillary sinus. Anatomy of the model extended 12 mm superior to the apices of the maxillary teeth. CBCT DICOM files were exported as an Axial series at 0.160 mm slice thickness.

An impression of the patient’s maxillary arch was made and poured in Die-Keen stone (Kulzer, South Bend, Indiana), and then optically scanned with a 3Shape benchtop D1000 scanner (3Shape, Warren, New Jersey). Resultant DICOMs from CBCT and STL from the scanner were uploaded into Mimics design software (Materialise Medical, Plymouth, Michigan). The scan was aligned to the patients’ CBCT using tooth surface data with multiple points of reference. Within Mimics, a Medical CAD/CAM Director and a Biomedical Engineer adjusted thresholding to digitally reproduce the patient’s maxilla. Prior to printing, the trephine path dictated by the original stent design utilized in the successful surgery was applied to the model within design Mimics Innovation Suite (Materialise Medical) software to produce a 6 mm diameter cylindrical void replicating the original osteotomy and root-end resection of tooth No. 2 that occurred in the successful clinical case. Thus, a single model with a clinically ideal osteotomy reproduced the surgical scenario (Figure 3A).

Pilot calibration: Each 3DP employs different data integration methods and printing mechanics and compatible resin.

Printed products conform to design software specifications to varying degrees based upon these factors. In order to understand the performance profiles of each test printer, multiple stents were produced and 12 Endodontic practice

A.

B.

Figures 2A and 2B: Assessment of dimensional hole conformity between printed object and STL for various printers. 2A. Templates of cylinders printed from three 3DPs from top to bottom: Objet 260, Form 2, Duplicator7. 2B. Geomagic Studio 2014 best fit cylinder tool used to digitally measure cylinder diameters

A.

B.

C.

D.

Figures 3A-3D: TEMS guide assessment model. 3A. Clinical simulation model for No. 2 palatal root resection derived from a successful previously published clinical case. 3B. 3DSGs (from left to right) Duplicator 7.0, Form 2, Objet 260. 3C. Clinically acceptable 3DSG on the simulation model. The rod extends through the osteotomy to the length of the depth indicator groove (arrow). 3D. Unacceptable 3DSG on the simulation model. The rod does not extend to the depth of the osteotomy; the depth indicator groove is completely visible (arrow)

guide port diameters were adjusted within design software until the same trephine bur of known diameter interacted with stents from each printer in a consistent and reproducible manner. This allowed examiners to adjust design software diameter settings, taking into consideration each individual printer’s distinctive performance characteristics. Resultant calibration port diameter

increases for the Objet260, Form 2, and the Duplicator7 were 0.05 mm, 0.15 mm, and 0.3 mm, respectively.

Stent fabrication: The same STL file used in the introductory TEMS publication for tooth No. 2 was used to print 30 guides from each of the three printers, applying calibration adjustments previously described above (Figure 3B). Objet260 Group: 3DSGs Volume 13 Number 1

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CLINICAL RESEARCH were printed with the Objet260 using proprietary MED610 resin (Stratasys, Eden Prairie, Minnesota). Form 2 Group: 3DSGs were printed with the Form 2 using NextDent SG resin (NextDent, Soesterberg, Netherlands).

Duplicator7 Group: 3DSGs were printed with Duplicator7 using NextDent SG resin.

Stent assessment: In order to avoid abrasion of the resin model osteotomy path by the cutting tip of the trephine during repeated insertion into the model osteotomy site, the trephine was measured with digital calipers, and a resin rod precisely replicating the bur diameter was designed and printed.

The rod had a 1-mm wide groove at one extent, indicating the proper insertion depth for a clinically acceptable stent.

The two Board-certified endodontists who pioneered the TEMS procedure tested the 3DSGs in the following manner.

Each guide was placed on the model and complete seating was verified by inspecting the disto-facial cusp of tooth No. 2 and the incisal edge of tooth No. 9 for intimate stent contact. Finger pressure was applied to the stent, and the rod was inserted through the guide tube. If the rod could be inserted to the full depth of the osteotomy (to the depth indicator groove) with clinically desirable interaction with the guide port, the 3DSG was considered acceptable (Figure 3C). 3DSGs that did not allow for complete insertion of the rod to the depth indicator groove, indicating either an errant osteotomy path or an anomaly in the guide tube diameter, were designated as unacceptable (Figure 3D).

Following testing, the rod was measured with digital calipers to ensure its diameter had not been reduced due to multiple passes through the guides. Finally, all 3DSGs were removed from the printed model, and the reference trephine (used to establish resin rod dimensions) was introduced within the lumen. This allowed verification that the interaction of the resin rod and the lumen replicated what would have occurred with the trephine if abrasion of the model were not a consideration. The data was then analyzed using a Fisher’s exact test, and interobserver agreement calculated using Cohen’s Kappa Coefficient.

Safe and effective TEMS relies upon an accurate 3DSG that can accommodate a trephine bur along a precisely designed pathway.

Results Part I All three printers produced objects that deviated from design dimensions, and the null hypothesis was rejected. For all diameters tested, the Objet260 had the lowest mean absolute deviation from the digital design (0.044 mm-0.067 mm) followed by the Form 2 (0.099 mm-0.166 mm). The Duplicator7 had the highest mean absolute difference for all diameters (0.222-0.321 mm). The results of Part I are summarized in Table 2. Post-hoc Tukey’s test determined the mean absolute differences were statistically significant between all three groups for all five diameters tested (p < 0.0001). There was no apparent correlation between diameter size and mean absolute difference for any of the printers.

Part II All 30 TEMS guides printed by the Objet260 and all 30 TEMS guides printed by the Form 2 successfully guided the rod to ideal osteotomy depth, and the null hypothesis was accepted. In contrast, 22/30 (73.3%) of surgical guides printed by the Duplicator7 allowed insertion of the rod to the ideal osteotomy depth, which was a statistically significant (p < 0.005). There was no interobserver disagreement for any stents tested; therefore kappa = 1. The null hypothesis was rejected. The Duplicator7 3DSG failures all resulted from constrictions or deviations within the stent lumen that would not allow rod penetration. When 3DSGs were removed from the model and tested with the reference trephine, all 3DSG lumens that accommodated the rod also

accommodated the trephine, and all 3DSG lumens that failed to accommodate the rod also failed to accommodate the trephine.

Discussion To our knowledge, this is the first investigation into the accuracy of 3DPs for TEMS. Previous studies comparing 3DPs for other dental applications have defined outcomes in terms of exact numerical measurements. In one study, there was no significant difference in replica teeth printed from a Fused Deposition Modeling (FDM) printer and a PolyJet device.11 Another study found that orthodontic models made from an SLA device had a statistically significant deviation when compared to PolyJet models only when a specific base geometry was used.13 Endodontic accuracy assessments demonstrated the Form 2’s acceptability for replicating extracted teeth14 and the Objet260’s suitability for guided access,6 but no previous endodontic studies have directly compared printers. There is no gold standard for evaluating these devices.16 Our model sought to simulate an actual clinical scenario documented in the endodontic literature in testing clinically relevant capabilities of the three printers.10 Thus, rather than merely comparing printed product measurements to design measurements, Part II of this study assessed each printer’s ability to consistently produce a clinically acceptable guide.

Based upon dozens of TEMS clinical cases, the authors knew all printed port lumens require a diameter increase over trephine dimensions within design software in order to accommodate the trephine.

TABLE 2. Deviations of planned and printed cylindrical voids for five endodontically-relevant diameters 1.6mm

2.35mm

4.0mm

5.0mm

6.0mm

O (mm)

F (mm)

D (mm)

O (mm)

F (mm)

D (mm)

O (mm)

F (mm)

D (mm)

O (mm)

F (mm)

D (mm)

O (mm)

F (mm)

D (mm)

Mean (absolute difference)

0.045

0.166

0.321

0.044

0.123

0.283

0.061

0.111

0.260

0.062

0.106

0.226

0.067

0.099

0.222

Standard deviation

0.031

0.061

0.074

0.034

0.031

0.055

0.061

0.023

0.056

0.049

0.036

0.070

0.021

0.035

0.058

Minimum

1.53

1.28

1.08

2.25

2.15

1.97

3.99

3.84

3.64

4.96

4.78

4.65

6.02

5.79

5.69

Maximum

1.71

1.52

1.38

2.50

2.28

2.16

4.37

3.93

3.83

5.21

4.95

5.10

6.12

5.95

5.99

Table 2: Deviations of planned and printed cylindrical voids for five endodontically-relevant diameters 14 Endodontic practice

Volume 13 Number 1

CLINICAL RESEARCH During post-printing inspection and before use, clinicians must verify that a trephine is able to penetrate the guide tube without resistance. If excessive resistance is encountered, and the trephine is “forced” to pass, it may create an “altered” path with undesirable clinical implications. If a guide tube is excessively larger than the trephine, the osteotomy could deviate from the desired path. The calibration assessment for each printer was utilized to account for differences in print product dimensions for individual printers. If all printers were adjusted with the same tolerance — for example, a 0.15 mm diameter increase over design — one printer could be privileged toward success or doomed to failure more than another based upon its functionality and the specific resin it used. If all printers were adjusted to the absolute mean from Part 1, the interaction of the trephine with the guide port still might not produce adequate clinical performance because of deviations from the mean along a lengthy port lumen.

In the pilot study, we started with values suggested by Part I and adjusted guide ports until desirable interaction with trephines repeatedly occurred, such that the trephine was guided with axial stability for reproduction of a “true” path. After several successive prints from each printer, a clinically oriented tolerance was established. Therefore, Part II assessed each printer’s ability to consistently reproduce clinically acceptable stents utilizing tolerances established in the pilot study.

Like the costly Objet260, the affordable Form 2 showed consistency in printing clinically acceptable 3DSGs for use in TEMS. Although the Duplicator7 produced clinically acceptable stents in the majority of cases, 26.7% of stents had a constricted lumen diameter precluding full insertion of the rod.

These stents would not have had clinical utility. Although our experimental model would suggest that all acceptable stents would produce desirable clinical results in vivo, it is impossible to conclude this absolute with certainty.

The results of Part I align well with results in Part II; the standard deviation for the 6.0 mm diameter hole was much higher for the Duplicator7 (0.058 mm) than it was for either the Connex 3 (0.021 mm) or the Form 2 (0.035 mm). This data predicted the lack of consistency of the Duplicator7 seen in Part II. “Off the box” printer specifications such as XY axis and layer thickness cannot be 16 Endodontic practice

used for side-by-side comparison of printers because they do not account for a multitude of factors that influence the accuracy of the final product. Potential inaccuracies during stent fabrication can be introduced during data acquisition, design, and fabrication.16,17 Product geometry, orientation, and even resin color may impact the quality of the printed product.18 This study could not control for effects of different resins as manufacturer requirements precluded use of the same resin in each printer. This experimental model shows a process that any lab or individual clinic would need to go through after acquiring a printer, in order to understand its performance characteristics. Other experimental models that merely report on dimensional conformity of object to design do not approach the subject of clinical utility.

These results should be interpreted narrowly, as an indication of performance consistency of these three printers in producing stents for TEMS. Indeed, widespread generalization of these data to all PolyJet, SLA, or DLP technical-type printer classifications across a wide array of dental applications is not warranted.

Conclusions Safe and effective TEMS relies upon an accurate 3DSG that can accommodate a trephine bur along a precisely designed pathway. A 3DSG that alters the path of the trephine or that altogether fails to accommodate the trephine must be discarded with subsequent delay or alteration in treatment. The Objet260 and Form 2 produced objects with low dimensional deviations from digital design.

Clinical Implications The Objet260 and the Form 2 consistently produced clinically acceptable 3DSGs and represent viable 3D printing options for TEMS applications.

Disclaimer The views expressed are those of the authors and do not reflect the official views or policy of the Department of Defense or its Components or the Uniformed Services University of the Health Sciences.

Acknowledgments Special acknowledgments to Mr. Daniel Sierra and Mr. James Pizzini at Air Force Postgraduate Medical CAD/CAM Lab. EP

REFERENCES 1. Lee SJ, Jung IY, Lee CY, Choi SY, Kum KY. Clinical application of computer‐aided rapid prototyping for tooth transplantation. Dent Traumatol. 2001;17(3):114-119.

2. Pinsky, HM, Champleboux, G, Sarment, DP. Periapical surgery using CAD/CAM guidance: preclinical results. J Endod.

2007;33(2):148-151.

3. Meer WJ, Vissink A, Ng YL, Gulabivala K. 3D computer aided treatment planning in endodontics. J Dent. 2016;45:67-72.

4. Strbac GD, Schnappauf A, Giannis K, et al. Guided autotransplantation of teeth: a novel method using virtually planned 3-dimensional templates. J Endod. 2016;42:1844-1850.

5. Strbac GD, Schnappauf A, Giannis K, Moritz, A, Ulm C. Guided modern endodontic surgery: a novel approach for guided osteotomy and root resection. J Endod. 2017;43(3):496-501.

6. Connert T, Zehnder MS, Weiger R, Kühl S, Krastl G. Microguided Endodontics: Accuracy of a Miniaturized Technique for Apically Extended Access Cavity Preparation in Anterior Teeth. J Endod. 2017;43(5):787-790.

7. Anderson J, Wealleans J, Ray J. Endodontic applications of 3D printing. Int Endod J. 2018;51(9):1005-1018.

8. Kim GB, Lee S, Kim H, et al. Three-Dimensional Printing: Basic Principles and Applications in Medicine and Radiology. Korean J Radiol. 2016;17(2):182-197.

9. Schoffer F. How expiring patents are ushering in the next generation of 3D printing. TechCrunch.com. 2016. https://techcrunch. com/2016/05/15/how-expiring-patents-are-ushering-in-the-next-generation-of-3d-printing/. Accessed on January 27, 2020.

10. Giacomino CM, Ray JJ, Wealleans JA. Targeted endodontic microsurgery: A novel approach to anatomically challenging scenarios using 3-dimensional-printed guides and trephine burs — a report of 3 cases. J Endod. 2018;44(4):671-677.

11. Lee KY, Cho JW, Chang NY et al. Accuracy of three-dimensional printing for manufacturing replica teeth. Korean J Orthod. 2015;45(5):217-225.

12. Favero CS, English JD, Cozad BE, et al. Effect of print layer height and printer type on the accuracy of 3-dimensional printed orthodontic models. Am J Orthod Dentofacial Orthop. 2017;152(4):557-565.

13. Camardella LT, de Vasconcellos Vilella O, Breuning H. Accuracy of printed dental models made with 2 prototype technologies and different designs of model bases. Am J Orthod Dentofacial Orthop. 2017;151(6):1178-1187.

14. Reymus M, Fotiadou C, Kessler K, et al. 3D printed replicas for endodontic education. Int Endod J. 2019;52(1):123-130.

15. Cristache CM, Gurbanescu S. Accuracy Evaluation of a Stereolithographic Surgical Template for Dental Implant Insertion Using 3D Superimposition Protocol. Int J Dent. 2017.

16. Block MS, Chandler C. Computed tomography – guided surgery: complications associated with scanning, processing, surgery, and prosthetics. J Oral Maxillofac Surg. 2009;67(Suppl 11):13-22.

17. D’haese J, Van De Velde T, Komiyama A, Hultin M, De Bruyn H. Accuracy and complications using computer-designed stereolithographic surgical guides for oral rehabilitation by means of dental implants: a review of the literature. Clin Implant Dent Relat Res. 2012;14(3):321-335.

18. Olszewski R, Szymor P, Kozakiewicz M. Accuracy of three-dimensional, paper-based models generated using a low-cost, threedimensional printer. J Craniomaxillofac Surg. 2014;42(8):1847-1852.

Volume 13 Number 1

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ENDODONTIC PERSPECTIVE

The Pendulum Swings Dr. John West discusses “Minimally Invasive” versus “Maximally Appropriate” The premise The concept of minimally invasive can be misleading in the world of endodontics.

An example of misuse of the phrase “minimally invasive” in endodontics would refer to making an access that did not predictably achieve of the Three Fs of endodontic treatment mechanics: “Find, Follow, and Finish.”

“Find” refers to discovering the root canal system’s orifi. “Follow” refers to navigating an endodontic file from canal orifice to the canal terminus. “Finish” means to (1) clean and disinfect the root canal labyrinth; (2) prepare an appropriate radicular shape that allows for a predictable conefit; (3) safe, controlled obturation with a material that can be removed if ever required; and (4) coronal seal placement to prevent future microleakage. A literal “minimally invasive” interpretation might suggest that the clinician should design the smallest access possible. That would mean an access with a quarter round bur! There would be no chance to “Find” all the canals.

But, of course, almost all the coronal tooth structure remains. If the canals were ever found through such a miniscule access, then a truly minimally shaped canal would be the size of a No. 6 file. There would be no chance to clean, no chance to disinfect, no chance for an intentional preparation design, and no chance for a 3D seal. Taken at its face value, “minimally invasive endodontics” (MIE) is an inaccurate distinction or, at least, a deceiving one. The suggestion is that smaller is better. Sometimes it is. But smaller (i.e., MIE) is only better if the desired outcomes of 3D endodontics are consistently and reproducibly achieved. If the access and shaping are too small, smaller is not better. The term “maximally appropriate endodontics” (MAE)

Dr. John West received his DDS degree from the University of Washington, where he is an affiliate professor. He is the founder and director of the Center for Endodontics in Tacoma, Washington, and a clinical instructor at Boston University. Dr. West and his two sons are in private endodontic practice in Tacoma. He can be reached via email at johnwest@centerforendodontics.com.

Disclosure: Dr. West reports no disclosures.

Volume 13 Number 1

is, to me, a more accurate and outcomerelated term.

The language The term minimally invasive is one of the current dental buzzwords like sameday dentistry or the use of the word platform in business. Sometimes I get tired of hearing these words because they are just that: buzzwords. As always, current, popular buzzwords will all fade over time and will be replaced with new buzzwords, such as maximally appropriate; dentistry now; patient-centered value; mindfulness; or, in the case of endodontics, a word such as endopreneur (a buzzword that I made up and trademarked — just because I could).

Consumer-targeted buzzwords are followed by new words that feed the consumer’s insatiable thirst for the latest and greatest. In the future, today’s buzzwords will be considered old-fashioned and out-of-date. Oh, how the pendulum swings!

MIE begs the question of how the role of ferrule fits into the invasive versus appropriate equation. Which distinction produces the best choice for both the dentist and the patient?

And so goes the ferrule and MIE. The balance between preservation of tooth structure (conservative) and appropriate (thoughtful) radicular preparations that

produce predictable 3D cleaning and 3Dcontrolled obturation are always on the endodontic clinician’s mind. For example, to extend the MB access of a maxillary second molar’s MB complex (mesiobuccal and mesiopalatal) in order to slide into the orifice’s distal orientation may not be considered a ninja-type access. A “conservative” access without sufficient extension for entering, a glidepath, and safe rotary instruments can make endodontic treatment technically impossible or even dangerous. What would you do if it were you being treated?

Would you tell your endodontist to save that precious MB dentin, or would you say, “Make it easy on yourself?” If you are like me, you would want your tooth’s attachment apparatus no matter what. With modern cements, if you make a new crown with a little less tooth structure, it will still predictably remain cemented. You would also tell your endodontist, who is designing your endodontic access cavity, that the critical part of the posterior teeth’s ferrule is not the mesial and distal; it is the buccal and lingual. If you are the patient, tell the endodontist, “Make it easy on yourself. Make sure you treat my endodontic anatomy.” This is the theme, thinking, and technique of MAE. The thought process of MIE has been used in recent years to describe the desired shape or taper and width of the radicular Endodontic practice 17

ENDODONTIC PERSPECTIVE funnel endodontic preparation. Advocates of MIE always show a buccal view of a posterior tooth and suggest it is overprepared and that the tooth is weakened. In many cases, their intentions are right and noble. We value the precious gift of dentin. We all want as much remaining dentin after our preps as possible, including in coronal restorative preparations.

Every bit of tooth helps the retention of the restorative and the longevity of the tooth. And, as our patient populations’ age increases, we are going to need to be predictable for longer and longer periods of time.

What really matters In endodontic posterior accesses, the critical measurement is not the mesial-distal remaining tooth structure; it is the buccallingual tooth structure that represents the resistance to forces, and it is this dimension that needs to be robust. Therefore, when a dentist evaluates remaining ferrule, considering the MIE philosophy, the more significant measurement should be made in the axial view of a 3D CBCT image. MAE-thinking understands that the buccal-lingual ferrule dimension is the critical measurement for access evaluation, not the mesial-distal, as many MIE evaluations suggest.

Nature gives us the rules of the endo endgame. Teeth remain in use for more than 100 years in the human body unless caries or trauma or restorations do not allow the teeth to sustain this 100-plus-year life. What is the width of Mother Nature’s canals at the canal orifice? It is the third-third-third rule. If nature has 2 times the dentin thickness of the canal, that would be appropriate for lifetime use, our preparations do not need to be narrower than nature’s. When the endodontic clinician shapes a calcified canal, for example, the finished mesial-distal preparation width should be anywhere from a fifth to a third of the width of the root at any given level. In this case, Mother Nature’s requirements are satisfied. The reward is endodontic predictability and root strength. Tapers generated by connecting the dots from the minimal apical constriction from a fifth to a third of the coronal root diameter will generate sufficient resistant form hydraulics to control a 3D obturation of the root canal system’s portals of exit.

The right direction There is one aspect, however, about the MIE narrative that I really appreciate and has made me a better endodontist. For me, MIE has increased my awareness of the shape of my radicular preparations from access 18 Endodontic practice

The term “maximally appropriate endodontics” (MAE) is, to me, a more accurate and outcome-related term.

to apex. Before the “MIE movement,” my access and shaping designs were going essentially unnoticed, as far as critically evaluating remaining tooth structure, when my endodontics were finished. Now, because of article after article and lecture after lecture, I completely agree with a focus on ferrule and pericervical dentin preservation while being simultaneously mindful that my job is to heal or prevent lesions of endodontic origin (LEOs). Every patient’s tooth is different; we all treat a different mix of patients; we are all in different stages of dental life requiring different needs; and we all have different skill levels. There are also growing differences in technologies used for access, cleaning and disinfection, shaping, and obturation. When any part of the Endodontic Triad develops disruptive change, disruptive change affects the remainder of the Triad, which can, in turn, affect the part of the Triad that forced the change in the first place. This sequence is not a vicious cycle but, rather, a dependent cycle. The critical endodontic outcome — the “Look” of the final radiographic endodontic look — is evolving. This transformational Look is directly related to improvements in any part of the Endodontic Triad.1 It is never fair to look at someone’s final endodontic image and pass judgment. We were not there. There may have been circumstances we are not aware of, such as the patient hardly being able to open his/her mouth, or the clinician was fatigued or behind in his/her schedule and decided the answer to being behind is to go faster. This is a bad choice, and it’s when mistakes happen.

Where does the pendulum swing from here?

So, what’s it all about? I believe the MIE/ MAE pendulum will keep swinging left and right, depending greatly on what new technologies enable dentists to improve one or more parts of the time-tested Endodontic Triad: clean, shape, and pack. Others may call it something different, but, so far, Mother Nature’s rules are simple: Reduce the threshold of the disease source, and she will heal. As an endodontic clinician, we give Mother Nature her best chance by making

shapes that can be cleaned and can be filled along all the root canal system’s walls and portals of exit. The trend is to make accesses and shapes smaller and smaller. Remember, smaller and smaller is not Mother Nature’s idea. She is quite content with shapes that are a fifth to a third of the root width in all dimensions. Under-shaped or unshaped canals tend to produce weak obturations and a lack of obturation control, which can be catastrophic. For example, in 2016, there was a $4.5 million verdict in a malpractice lawsuit for a case in which a clinician filled up the mandibular canal during endodontic obturation. In this case, it appears to have been a failure to design a resistance form, funnel-shaped preparation. Therefore, the filling material could not be contained within the root canal system and flowed unrestricted into the mandibular canal. Endodontic radicular design requires meticulous preparation and is particularly challenging since, in endodontics, we do it in the dark. We cannot directly make our preps. We cannot see and do at the same time. We now have instruments that can improve our predictability of success, but sometimes there is little room for error. Welcome to dentistry!

Without appropriate resistance form in all dimensions, overfills and overextensions of under-filled systems would undoubtedly increase. As dentists, this loss of confidence is everything. What had been fun would become feared. Ultimately, we value the three Cs: consistency, which leads to control, which leads to confidence. Armed with the knowingness that we can prove our endodontic preps are appropriately finished through the conefit, you can enjoy the procedure, and your patient will enjoy success.

And so, that’s it! Not too big, and not too small.

Just right — and appropriate! EP

REFERENCE 1. West J. The Evolving Look of “The Look.” Dentistry Today. Created June 2019. https://www.dentistrytoday. com/endodontics/10569-the-evolving-look-of-the-look.

Accessed on January 28, 2020.

This article was reprinted with permission from Dentistry Today.

Volume 13 Number 1

CLINICAL

Management of a large external inflammatory root resorption Drs. Renato Piai Pereira, Murilo Priori Alcalde, Rodrigo Ricci Vivan, Marco Antonio Hungaro Duarte, Rogério Vieira Silva, and Clóvis Monteiro Bramante describe the therapeutic approach for a case of inflammatory external root resorption Abstract Introduction External inflammatory root resorptions are pathologies that are difficult to treat.

The treatment aims to eliminate the cause or stimulating factors of clastic cells such as infection and/or pressure. The size and location of the lesions are limiting factors for the treatment and maintenance of the affected tooth.

Objective The objective of this study was to describe the therapeutic approach of a case of inflammatory external root resorption.

Methods A 40-year-old female patient was referred for endodontic treatment of tooth No. 30, diagnosed with external inflammatory root resorption. The patient was scheduled for

endodontic therapy with calcium hydroxide paste dressing to seal the resorbed area of root canal space with MTA and coronary restoration with composite resin.

Results and Conclusion Clinical and radiographic follow-up after 1 year showed an absence of symptomatology, repair of the periapical region, and paralysis of resorption.

Introduction Root resorption is a pathological process that occurs in permanent teeth both internally and on the outer root surface. Resorption occurs when the pre-dentin layer and odontoblasts present in the root canal, or when the pre-cementum and cementoblasts in the periodontal ligament (PDL) are damaged or removed.1 The etiology is mainly associated with dental trauma, surgical procedures, and excessive pressure of impacted teeth or tumors. It can also occur due to chemical

irritation during tooth whitening and orthodontic movement procedures.1,2 Teeth affected by resorptive lesions are usually asymptomatic, and in many situations, the diagnosis may present as an incidental finding on routine radiographic examinations.3 Once resorption is detected, cone beam computed tomography (CBCT) is the test of choice to determine the location, extent, and differentiation of lesions, which are important for establishing an appropriate treatment plan and prognosis.4,5 Root resorption occurs in three stages: initiation, resorption, and repair.6,7 The process may have a self-limiting characteristic and may not be clinically detected.8 Once started, resorption depends on common factors that stimulate clastic cells, such as infection and/or pressure, to progress the destruction of mineralized dental tissue. Since the treatment of inflammatory resorption is primarily aimed at removing stimulation factors,9 in cases of inflammatory

Renato Piai Pereira, DDS, MSc, is Professor of the State University of Southwest Bahia (UESB).

At the moment, he is a PhD candidate of the Department of Operative Dentistry, Endodontics, and Dental Materials at the Bauru School of Dentistry (FOB/USP).

Murilo Priori Alcalde , PhD, is Professor of the Department of Operative Dentistry, Endodontics, and Dental Materials at Bauru School of Dentistry and Professor of Endodontics at Sacred Heart University.

Rodrigo Ricci Vivan, PhD, is Professor of the Department of Operative Dentistry, Endodontics, and Dental Materials at Bauru School of Dentistry.

Marco Antonio Hungaro Duarte, PhD, is Head Professor of the Department of Operative Dentistry, Endodontics, and Dental Materials at Bauru School of Dentistry.

Rogério Vieira Silva, PhD, is a professor at the Department of Dentistry, Faculdade Independente do Nordeste (FAINOR), Bahia, Brazil.

Clóvis Monteiro Bramante, PhD, is a Senior Professor of the Department of Operative Dentistry, Endodontics and Dental Materials at Bauru School of Dentistry.

Disclosure: Authors deny any conflict of interest or financial disclosure.

Figure 1: Initial periapical radiograph of the right lower first molar 20 Endodontic practice

Volume 13 Number 1

CLINICAL

root resorption associated with root canal infection, endodontic treatment usually has a favorable prognosis. Calcium hydroxide is the drug of choice because of its antimicrobial action, pH, necrosis of the granulation tissue present in resorption gaps, and its ability to stimulate repair.3 Based on these findings, the objective of this study was to describe the therapeutic approach of a case of inflammatory external root resorption.

Case description A 40-year-old female patient was referred for endodontic treatment diagnosed with tooth pulp necrosis of lower right first molar.

The medical history was not relevant. On clinical examination, tooth No. 30 had an extensive composite resin restoration. The thermal and electric sensitivity pulp tests had negative responses, while percussion and palpation were positive. The periodontal evaluation showed normal-colored gingival tissues and the absence of periodontal pockets. The radiographic examination showed the presence of nodules and narrowing of the pulp chamber, and in the periapical tissues, it was possible to identify a discrete radiolucent area lateral to the distal root of the tooth (Figure 1). Thus, the established pulp and periapical diagnoses were pulp necrosis and symptomatic apical periodontitis, respectively.

After endodontic treatment was instituted, access was performed with diamond spherical drills through the occlusal face.

After access, it was difficult to locate one of the mesial conduits, so a CBCT was performed to assist in the anatomical understanding and consequent localization of the conduits. In addition to the conduit location, an extensive external inflammatory resorption lesion on the lateral surface and apical third of the distal root of tooth No. 30, communicating with the root canal, was identified on tomography (Figure 2). Soon the initial planning was changed to include resorption treatment. At the second visit, the canals were instrumented (Figure 3A), irrigated with 5.25% sodium hypochlorite and final agitation of 17% EDTA by means of an ultrasound insert (Irrisonic; Helse Ultrasonic, Santa Rosa de Viterbo, Brazil), with an application time of 1 minute by canal. The conduits, including the reabsorbed area, were filled with calcium hydroxide paste (Ultracal™ XS; Ultradent Products, Inc., South Jordan, Utah).

At the third visit, the intracanal medication was removed following the same irrigation protocol described earlier. The resorbed area was filled internally with MTA Volume 13 Number 1

Figures 2A and 2B: 2A. CBCT preoperative sagittal section. 2B. CBCT preoperative axial section. Aspects showing an extensive root resorption associated with distal root

Figures 3A and 3B: 3A. Periapical radiograph for determination of working length. 3B. Periapical radiograph for control of MTA insertion

Figure 4: Final periapical radiograph showing the resorption defect filled with MTA and remaining distal canal filled with gutta percha and endodontic cement

Repair HP (Angelus, Londrina, Brazil). Filling of the resorbed area was performed by interspersing the MTA condensation with radiographic examinations to ensure the complete sealing of the area and to prevent material leakage to the periodontium (Figure 3B). Endodontic obturation followed the vertical compression technique using Touch

‘n Heat™ 5004 (Kerr, Orange, California) with gutta-percha points and AH Plus® cement (Dentsply Detrey, Konstanz, Germany).

The restorative procedure was performed at the end of the endodontic treatment in the same session (Figure 4). The inlet ducts were sealed with glass ionomer cement.

The clinical sequence proceeded with the Endodontic practice 21

CLINICAL application of 35% phosphoric acid gel (Ultradent Products, Inc., South Jordan, Utah) for 20 seconds. The enamel and dentin surfaces were then washed and dried.

The bonding agent (Tetric® N-Bond; Ivoclar Vivadent, Amherst, New York) was applied and polymerized according to the manufacturer’s instructions. The pulp chamber was filled with a low-viscosity single increment resin, SureFil SDR® Flow (Dentsply Caulk, Milford, Delaware). The occlusal anatomy was obtained using a high-viscosity nanohybrid composite resin, IPS Empress® Direct (Ivoclar Vivadent, Amherst, New York). After removal of the rubber dam, the restoration was occluded and adjusted.

Clinical and radiographic control at 1 year showed an absence of symptoms, and CBCT images showed a regression of the bone lesion and paralysis of the resorption process (Figure 5).

Discussion The diagnosis of resorption lesions usually occurs through incidental findings on routine radiographic examinations, especially in early cases where there is no symptomatology.8 In contrast, the limitations of dental radiographic examinations are widely known3; periapical radiographs tend to underestimate the size of resorption lesions, while CBCT provides a more accurate estimate.10,11 Currently, CBCT is an important resource for the diagnosis and treatment of resorption, as it allows the identification of its correct location and extension.4,12 In the present case report, resorption was not clearly visible at the initial radiographic examination. The diagnosis was possible only after a CBCT was performed.

The treatment of root resorption is not always possible; the size, location, and restorability of the tooth are difficult obstacles to overcome.13 The therapeutic principle of dental resorption is based on the identification and elimination of the cause or factors that stimulate clastic cells, such as infection and/or pressure.9,14 For some authors, the prognosis is good when the stimulation is endodontic infection or orthodontic pressure. When the stimulation factor is periodontal infection, the prognosis may be unpredictable.3 Endodontic infection can stimulate or sustain inflammation in the PDL and lead to root resorption. Endodontic treatment, combined with calcium hydroxide paste dressing, interrupts the inflammatory process of resorption and allows periradicular recovery.15 In the present case, the control of root canal infection and the sealing of the 22 Endodontic practice

Figures 5A and 5B: 5A. CBCT postoperative sagittal section after 1-year of follow-up. 5B. CBCT postoperative axial section after 1-year of follow-up. Aspects showing the regression of bone lesion and paralysis of the resorption process

MTA resorbed area were determinants for the prognosis of the treated tooth. The intracanal medication used, based on calcium hydroxide, also aimed to control bleeding and necrosis of granulation tissue present in the resorbed area, thus facilitating the internal repair of the lesion through the use of a repair cement, MTA HP repair. In this treatment, one of the challenges was the internal filling with the repairing cement of the resorption defect, since it was located in the apical third of the distal root of the lower molar. The result was achieved with the use of small endodontic compactors. The insertion of the MTA in the reabsorbed area was similar to the apical plug technique.16 Decision-making regarding the treatment of resorption should be based on the nature and cause of resorption, prognosis, and restorability of the tooth. The risks and

benefits should be widely discussed with the patient.8 In addition to functional and esthetic restoration of the affected teeth, the treatment aims to stop the resorption process, and for this reason, a long-term follow-up is necessary to rule out the recurrence of this pathology. When conservative treatment by internal or surgical approach is not possible, other treatment options should be considered, including intentional replantation, periodic follow-up, or extraction.17

Conclusion Based on the clinical, radiographic, and tomographic findings, the patient’s general health and the application of scientifically supported techniques, this clinical case showed the possibility of treating an external resorption by an internal approach with a satisfactory outcome. EP

REFERENCES 1.

Leach HA, Ireland AJ, Whaites EJ. Radiographic diagnosis of root resorption in relation to orthodontics. Br Dent J. 2001;190(1):16-22.

2.

Fuss Z, Tsesis I, Lin S. Root resorption - diagnosis, classification and treatment choices based on stimulation factors. Dent Traumatol. 2003;19(4):175-182.

3.

Darcey J, Qualtrough A. Resorption: part 2. Diagnosis and management. Br Dent J. 2013;214(10):493-509.

4.

Fayad MI, Nair M, Levin MD, et al. AAE and AAOMR joint position statement: use of cone beam computed tomography in Endodontics 2015 update. Oral Surg Oral Med Oral Pathol Oral Radiol. 2015;120(4):508-512

5.

Patel S, Dawood A. The use of cone beam computed tomography in the management of external cervical resorption lesions.

Int Endod J. 2007;40(9):730-737.

6.

Mavridou AM, Hauben E, Wevers M, et al. Understanding external cervical resorption patterns in endodontically treated teeth.

Int Endod J. 2017;50(12):1116-1133.

7.

Mavridou AM, Hauben E, Wevers M, et al. Understanding External Cervical Resorption in Vital Teeth. J Endod.

2016;42(12):1737-1751.

8.

Patel S, Saberi N. The ins and outs of root resorption. Br Dent J. 2018;224(9):691-699.

9.

Tsesis I, Fuss Z, Rosenberg E, Taicher S. Radiographic evaluation of the prevalence of root resorption in a Middle Eastern population. Quintessence Int. 2008;39(2):e40-e44.

10. Ball RL, Barbizam JV, Cohenca N. Intraoperative endodontic applications of cone-beam computed tomography. J Endod.

2013;39(4):548-557.

11. Patel S, Dawood A, Ford TP, Whaites E. The potential applications of cone beam computed tomography in the management of endodontic problems. Int Endod J. 2007;40(10):818-830.

12. Vaz de Souza D, Schirru E, Mannocci F, Foschi F, Patel S. External Cervical Resorption: A Comparison of the Diagnostic Efficacy Using 2 Different Cone-beam Computed Tomographic Units and Periapical Radiographs. J Endod. 2017;43(1):121-125.

13. Smidt A, Nuni E, Keinan D. Invasive cervical root resorption: treatment rationale with an interdisciplinary approach. J Endod.

2007;33(11):1383-1387.

14. Consolaro A. The four mechanisms of dental resorption initiation. Dental Press J Orthod. 2013;18(3):7-9.

15. Ricucci D, Siqueira JF Jr, Loghin S, Lin LM. Repair of extensive apical root resorption associated with apical periodontitis: radiographic and histologic observations after 25 years. J Endod. 2014;40(8):1268-1274.

16. Pace R, Giuliani V, Pini Prato L, Baccetti T, Pagavino G. Apical plug technique using mineral trioxide aggregate: results from a case series. Int Endod J. 2007;40(6):478-484.

17. Ehlinger C, Ginies E, Bornert F, et al. Decision criteria influencing the therapeutic approach to invasive cervical resorption: a case series. Quintessence Int. 2019;50(6):494-502.

Volume 13 Number 1

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CLINICAL RESEARCH

Efficacy of different procedures in removing radiopaque organic material from simulated internal root resorption cavities: an ex vivo study Drs. Claudia Hernández Restrepo, Gonzalo García, Denise Alfie, Sharon R. Oyhanart, and Fernando Goldberg discuss removing organic material from simulated internal resorption cavities Abstract Introduction This study aims to evaluate the efficiency of different procedures in the removal of artificial organic radiopaque material from simulated internal root resorption cavities of maxillary central incisors.

Materials and methods Thirty extracted human maxillary central incisors were instrumented up to the working length (WL) with WaveOne® Gold Medium (WOG) (Dentsply Sirona, Ballaigues, Switzerland). Teeth were sectioned transversally at 7 mm from the anatomic apex, and cavities were drilled on the root canal of each half. Cavities were filled with organic material (corned beef, Swift, Santa Fe, Argentina) mixed with AH Plus® paste B (Dentsply Sirona) and glued back together in order to simulate an internal root resorption (IRR). All the samples were instrumented with WOG Large up to WL and divided into three groups of 10 specimens.

Group 1: Passive manual irrigation.

Group 2: Irrigation was agitated by EndoActivator® (Dentsply Tulsa Dental Specialties, Tulsa, Oklahoma).

Group 3: Irrigation was activated with XP-endo Finisher (FKG Dentaire SA, La Chaux-de-Fonds, Switzerland).

Radiographs were taken to assess the presence of residual organic radiopaque material. A score was stablished to evaluate the samples: 0, absence of organic material; 1, organic material on one wall; 2, on two walls; 3, on three walls; 4, on all of the walls. The evaluation was performed by two Claudia Hernández Restrepo, DDS; Gonzalo García, DDS; Denise Alfie, DDS, PhD; Sharon R. Oyhanart, DDS; 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.

24 Endodontic practice

endodontic specialists. Data was statistically analyzed using InfoStat version by means of a non-parametric Kruskall-Wallis test with multiple comparisons. Significance level was set at p < 0.05.

Results Group 3 showed the best results followed by Group 2 and Group 1. XP-endo Finisher and EndoActivator showed a statistically significant better performance when compared to passive manual irrigation (p < 0.05), but no differences were found between the former two.

Conclusion XP-endo Finisher and EndoActivator showed significantly better results than passive manual irrigation in removing organic radiopaque material from simulated internal resorption cavities.

Introduction An internal root resorption (IRR) is an inflammatory process initiated within the dental pulp that causes the resorption of dentin and possible invasion of cementum following the resorptive activity of clastic cells upon predentin and odontoblastfree dentin walls. Different etiologic factors have been proposed among which caries, dental trauma, periodontal infections, and orthodontic treatment, but it may also be rendered idiopathic.1,2 Under such circumstances, regardless whether dental pulp is still vital or necrotic at the time of diagnosis, endodontic treatment must be delivered, and its success will depend on the extent to which cleaning, disinfection, and obturation procedures can be satisfactorily performed.3 Teeth affected by IRR represent an endodontic challenge since the irregularities of the resorptive cavity present an impediment to irrigation and instrumentation as well as making it difficult for intracanal medicaments and obturation materials to reach

these areas.1,2 Moreover, given the difficulty found in thoroughly eliminating bacteria and tissue debris from these cavities, strategies aimed at effectively removing them are necessary.1,2,4,5 Different irrigation techniques, intracanal medicaments, and instruments have been proposed to complete canal disinfection in such cases.1,2,4 However, a number of studies stress the difficulty in achieving this goal even in canals that display a normal anatomy.6 In teeth with IRR and vital pulp, the total removal of the organic tissue in order to stop the resorptive mechanism is very important, while in teeth with pulp necrosis, the persistence of necrotic tissue and bacteria may compromise the success of endodontic therapy.3 In order to disinfect the root resorptive cavity, some authors recommend the use of calcium hydroxide as an intracanal interappointment medicament.1,2,7 EndoActivator (Dentsply Tulsa Dental Specialties, Tulsa, Oklahoma) and XP-endo Finisher (FKG Dentaire SA, La Chaux-deFonds, Switzerland) are used to agitate irrigants within the root canal space in order to remove organic and inorganic remnants. This oscillating effect could improve the removal of the contents occupying the IRR cavity.

EndoActivator, is a device for sonic activation of irrigant solutions that agitates the fluid within the canal by means of an oscillating non-cutting polymer tip. This tip is available in three different sizes (15/02, 25/04, and 35/04) and can be driven at three different frequencies (2,000, 6,000, and 10,000 cycles per minute) using a button present in its handpiece.9,10 XP-endo Finisher is a non-tapered nickeltitanium instrument made of a proprietary alloy (MaxWire®; Martensite-Austenite Electropolish FleX, FKG Dentaire) with a small core size of #25 in caliber capable of changing its shape according to temperature. It displays a straight geometry at room temperature and Volume 13 Number 1

Materials and methods Sample selection and standardization Thirty extracted human maxillary central incisors with complete root formation and a single straight canal were selected by means of direct examination and the aid of preoperative radiographs taken in the buccolingual and mesiodistal directions. Teeth with large caries lesions, radicular fractures, and/ or resorptions were excluded. To ensure sample standardization, the crowns of the selected teeth were, when needed, partially removed to achieve a final length of 21 mm using a low-speed carborundum disc under constant water cooling. Teeth were stored in 2.5% NaOCl for 48 hours and then washed under running water before experimental procedures.

Root canal instrumentation Access to the canal was established by conventional technique and patency confirmed using a size 10 K-file (Dentsply Sirona, Ballaigues, Switzerland) until its tip was visible through the main foramen.

Working length for each sample was determined by subtracting 1 mm from this measurement. Root canals were prepared up to WL using WOG Medium in a reciprocating motion. For this procedure an X-Smart® Plus

Figure 1: (left) View of both hemisections. (right) Hemisections with the round cavities drilled Volume 13 Number 1

motor (Dentsply Sirona, Ballaigues, Switzerland) was used following the manufacturer’s instructions. During instrumentation and as a final rinse, the canals were irrigated with 3 ml of 2.5% NaOCL using a NaviTip™ No. 30 needle (Ultradent Products Inc., South Jordan, Utah).

Internal root resorption cavities preparation To facilitate the tooth sample repositioning, a line was drawn following the long axis. Teeth were sectioned transversally at a distance of 7 mm from anatomic apex using a low-speed carborundum disc (Dentorium, New York, New York) under constant water cooling. A semicircular standardized cavity was then drilled on the root canal of each half using a round No. 5 bur with a metal stop to ensure that it would penetrate at a similar depth every time (Figure 1). Both cavities of each sample were filled with 1.80 gr of organic material (corned beef, Swift, Santa Fe, Argentina) mixed with 1.00 gr of AH Plus paste B (Dentsply Sirona), weighed using an electronic precision scale (Hometech EHA 501, China). Both halves of each tooth were glued back together using a cyanoacrylate adhesive (La Gotita, Akapol S.A., Argentina).

In order to confirm that cavities had been entirely filled, digital radiographs were taken in buccolingual and mesiodistal directions.

Once adhesion was established, samples were included in plastic tubes full of Reprosil® Putty (Dentsply Caulk, Milford, Delaware).

After polymerization, samples were kept at 37 ºC and 100% relative humidity for 7 days.

Organic radiopaque material removal protocols Canals were then instrumented up to WL using WOG Large in a reciprocating motion according to manufacturer’s instructions. For

this procedure, an X-Smart Plus motor was used. Root canals were irrigated with 2 ml of 2.5% NaOCl using and a NaviTip No. 30 needle calibrated with a silicone stop at 17 mm to guarantee the tip of the needle would exceed the depth of the resorption cavities.

Specimens were then randomly separated into three groups of 10.

Group 1 (N=10): Root canals were manual passive irrigated with 6 ml of 2.5% NaOCl using the same procedure previously mentioned.

Group 2 (N=10): Root canals were irrigated with 3 ml of 2.5% NaOCl using the same procedure previously mentioned. Then EndoActivator at 10,000 cycles per minute with a polymer tip #35/04 was used to agitate the solution during 90 seconds with a pumping motion. A final rinse with 3 ml of 2.5% NaOCl ended the protocol.

Group 3 (N=10): Root canals were rinsed with 3 ml of 2.5% NaOCl, and an XP-endo Finisher file was used with an X-Smart Plus motor inserted at the WL and engine at a speed of 800 rpm and torque 1 Ncm (according to manufacturer) and operated during 90 seconds with a gentle in-and-out movement. A final rinse with 3 ml of 2.5% NaOCl ended the protocol.

Each instrument was discarded after being used in three root canals. All samples were treated by the same operator. All the groups procedures were carried out at 37 °C inside an incubator (Figure 2).

Evaluation and scoring Mesiodistal and buccolingual radiographs were taken in order to assess the presence of residual organic radiopaque material, therefore considering all four walls of the IRR cavities. Two calibrated specialists in endodontics, who were blinded to the

Figure 2: Incubator with an acrylic protection containing a rectangular perforation that allows samples handling at 37 ºC Endodontic practice 25

CLINICAL RESEARCH

transforms into the austenite phase when exposed to body temperature, changing its morphology, and becoming more flexible while expanding when in rotary motion.11 The aim of the present study was to evaluate in an ex vivo model the ability of different irrigation protocols (i.e., passive manual irrigation, EndoActivator, and XP-endo Finisher) to eliminate artificial organic radiopaque material from simulated IRR in human maxillary central incisors.

CLINICAL RESEARCH experimental groups, scored each sample independently according to the amount of organic radiopaque material remaining inside the IRR (Figure 3): 0: Cavity free of organic radiopaque material 1: Presence of organic radiopaque material on one of the walls of the cavity 2: Presence of organic radiopaque material on two walls of the cavity 3: Presence of organic radiopaque material on three walls of the cavity 4: Presence of organic radiopaque material on all the walls of the cavity Data was statistically analyzed using InfoStat version by means of a non-parametric Kruskall-Wallis test with multiple comparisons. Significance level was set at p < 0.05.

Results Group 3 showed the best results followed by Group 2 and Group 1 (Table 1).

EndoActivator and XP-endo Finisher showed a statistically significant better performance when compared to passive manual irrigation (p < 0.05), but no differences were found between the former two (Table 2).

Discussion The goal of an endodontic treatment is to clean, disinfect, and obturate the root canal system.3 In certain cases, anatomic anomalies may be present, therefore challenging clinicians and making the delivery of an adequate treatment very difficult, or even impossible.

In situations in which an IRR is present, normal root canal walls are adjacent to a cavity of irregular walls that may contain organic vital pulp or necrotic tissue and bacteria. Their removal by means of instruments, irrigation, and intracanal medicaments is of utmost importance.

In this study, a model published by Goldberg, et al.,8 was used. Simulated IRR cavities were filled with organic material in order to mimic a clinical setting. A radiopaque paste allows it radiographic observation and evaluation. Ulusoy, et al.,4 in an ex vivo study comparing different irrigation solutions activated by passive ultrasonic activation and XP-endo Finisher on the removal of organic material from simulated internal resorption cavities arrived at similar results than the present study by demonstrating the effectiveness of XP-endo Finisher.

Several clinicians use calcium hydroxide as an intracanal interappointment medicament to achieve greater antibacterial effect against microorganisms surviving chemomechanical 26 Endodontic practice

Figure 3: Radiographic images corresponding to the different categories

Table 1: Group scores Sample

Group 1 (Passive Manual Irrigation)

Group 2 (EndoActivator)

Group 3 (XP-endo Finisher)

1

4

0

0

2

3

2

0

3

4

0

2

4

2

0

0

5

3

0

2

6

4

3

0

7

2

3

0

8

0

1

0

9

4

3

0

10

4

3

3

preparation. However, different authors stress the difficulty in removing calcium hydroxide from IRR cavities.5,7,10,12-16 The persistence of calcium hydroxide inside the cavity affects physical properties of endodontic sealers interfering with their adhesion to dentin walls and hindering tridimensional filling of the resorptive cavity.5,10, 12-18 Even though organic tissue present in the IRR prior to treatment differs from calcium hydroxide in its characteristics and possible dissolution mechanisms, the method used to evaluate cleanliness of resorptive cavities is rather similar. In this respect, findings by Keskin, et al.,5 match our own by showing

Table 2: Statistical processing and analysis of data Group

N

Mean

SD

Median

1

10

3.0a

1,33

3,5

2

10

1,5b

1,43

1,5

3

10

0,7b

1,16

0,0

Different letters indicate statistically significant differences (p < 0.05).

that XP-endo Finisher performed better in removing calcium hydroxide from simulated internal resorptions of single-rooted teeth.

Volume 13 Number 1

the irregular lesions generated by the internal root resorption process. We therefore stress the need to interpret the results of these experiments with caution with regards to clinical practice.

Conclusion EndoActivator and XP-endo Finisher showed significantly better results than passive manual irrigation in removing organic material from simulated internal resorption cavities.

Acknowledgments Appreciation to Dr. Ricardo L. Macchi for his collaboration in the statistical evaluation. EP

REFERENCES 1. Haapasalo M, Endal U. Internal inflammatory root resorption: the unknown resorption of the tooth. Endod Topics.

2008;14(1):60-79.

7. Mohammadi Z, Dummer P. Properties and application of calcium hydroxide in endodontic and dental traumatology.

Int Endod J. 2011;44(8):697-730.

8. Goldberg F, Massone EJ, Esmoris M, Alfie D. Comparison of different techniques for obturating experimental internal resorptive cavities. Endod Dent Traumatol.

2000;16(3):116-121.

9. Jiang L-M, Verhaagen B, Versluis M, van der Sluis LWM. Evaluation of a sonic device designed to activate irrigant in the root canal. J Endod. 2010;36(8):143-146.

10. Alturaiki S, Lamphon H, Edrees H, Ahlquist M. Efficacy of 3 different irrigation systems on removal of calcium hydroxide from the root canal: a scanning electron microscopic study.

J Endod. 2015;41(1):97-101.

11. Trope M, Debelian G. XP-3D Finisher file — the next step in restorative endodontics. Endodontic Practice US. 2015;8:22-24.

12. Topçuoglu HS, Düzgün S, Ceyhanli KT, et al. Efficacy of different irrigation techniques in the removal of calcium hydroxide from simulated internal root resorption cavity.

Int Endod J. 2015;48(4):309-316.

13. Wigler R, Dvir R, Weisman A, Matalon S, Kfir A. Efficacy of XP-endo finisher files in the removal of calcium hydroxide paste from artificial standardized grooves in the apical third of oval root canals. Int Endod J. 2017; 50(7):700-705.

14. Göktürk H, Özkoçak I, Büyükgebiz F. Effect of temperature on the ability of XP-endo Finisher to remove calcium hydroxide from root canal irregularities: ex vivo. Acta Odontol Turc. 2018;35:38-43.

3. Schilder H. Cleaning and shaping the root canal. Dent Clin North Am. 1974;18(2):269-296.

15. Kfir A, Blau-Venezia N, Goldberger T, Abramovitz I, Wigler R. Efficacy of self- adjusting file, XP-endo Finisher and passive ultrasonic irrigation on the removal of calcium hydroxide paste from an artificial standardized groove. Aust Endod J. 2018;44(1):26-31.

4. Ulusoy ÖI, Savur IG, Alaçam T, Çelik B. The effectiveness of various irrigation protocols on organic tissue removal from simulated internal resorption defects. Int Endod J. 2018;51(9):1030-1036.

16. Donnermeyer D, Wyrsch H, Bürklein S, Schäfer E. Removal of calcium hydroxide from artificial grooves in straight root canal: sonic activation using EDDY versus passive ultrasonic irrigation and XPendo Finisher. J Endod. 2019;45(3):322-326.

5. Keskin C, Sariyilmaz E, Sariyilmaz Ö. Efficacy of XP- endo finisher file in removing calcium hydroxide from simulated internal resorption cavity. J Endod. 2017;43(1):126-130.

17. Hosoya N, Kurayama H, Iino F, Arai T. Effects of calcium hydroxide on physical and sealing properties of canal sealers. Int Endod J. 2004;37(3):178-184.

6. Siqueira JF Jr, Roças IN, Santos SRLD, et al. Efficacy of instrumentation techniques and irrigation regimens in reducing the bacterial population within root canals. J Endod. 2002;28(3):181-184.

18. Uzunoglu-Özyürek E, Endorgan Ö, Türker SA. Effect of calcium hydroxide dressing on the dentinal tubule penetration of 2 different root canal sealers: a confocal laser scanning microscopic study. J Endod. 2018;44(6):1018-1023.

2. Patel S, Ricucci D, Durak C, Tay F. Internal root resorption: a review. J Endod. 2010;36(7):1107-1121.

NEW! THE DENTAL CLINICAL COMPANION PODCAST Bringing together the world’s leading clinicians and experts to optimize your treatment, educate, and inspire and energize your professional goals.

Hosted by: Dr. Richard Mounce Listen now at www.dentalclinicalcompanion.com

Volume 13 Number 1

Endodontic practice 27

CLINICAL RESEARCH

Furthermore, Wigler, et al13 and Kfir, et al.,15 also demonstrated better results after using XP-endo Finisher to clean artificial grooves filled with calcium hydroxide.

On the other hand, Donnermeyer, et al.,16 found that sonic and passive ultrasonic irrigation were more effective in the removal of calcium hydroxide from apical grooves than XP-endo Finisher. In our study, all cleaning protocols were performed at 37 °C, simulating clinical conditions under which XP-endo Finisher instrument would expand acquiring a spoon shape over the apical few millimeters due to its MaxWire alloy. Interestingly, Göktürk, et al.,14 found that XP-endo Finisher was able to produce better results when used at a temperature of 37 °C. Regarding the use of EndoActivator, Alturaiki et al.,10 obtained higher degrees of removal of calcium hydroxide when comparing it to ultrasonic passive irrigation and negative apical pressure. In the present study, even though EndoActivator performed better than conventional manual irrigation, it produced less satisfactory results than the XP-endo Finisher although this difference was not statistically significant.

It is also important to mention, following Topçuoglu, et al.,12 that using round burs to fabricate standardized IRR creates uniform well-characterized cavities that differ from

TECHNOLOGY

Adaptive core instruments — perfect for retreatment Drs. Martin Trope, Klaus Lauterbach, and Gilberto Debelian discuss how these files clean the canal in all dimensions with minimal removal of dentin

R

etreating a previously obturated root canal provides a unique set of challenges. First, the canal has already been instrumented so that the shape and remaining wall thickness is no longer in the control of the retreating practitioner. Removing the filling material can be difficult and sometimes impossible. If successful in removing the main core of filling material, as practitioners we must then disinfect the canal to remove microbes and substrate that were the cause of the failure in the first place.

Traditionally, we use the same type of files for retreatment that we have used in the initial treatment. These files have round shapes with cores that take up most of the space in the canal. The core gutta percha is softened with solvent, and then these files are used to remove the material in the same way they were used initially to do the first root canal. With most traditional files, the file core takes up the entire space provided by the canal. This creates a problem in that there is no place for the previous filling material to go. Thus, too much of the old filling material is pushed laterally

Figure 1: The file has a dimension of No. 30 at the tip with a 0.01 taper. The small tip and taper ensure that the file maintains flexibility, does not take up the entire space in the canal, and can be used safely at a high speed. The Booster Tip allows it to enter any space that is equivalent to 15/02 or 10/04

in the canal, filling any available irregularity in the canal and limiting the effectiveness of any disinfectant or agitating device that comes after the core of the original filling is removed. Now, in order to remove the microbes that are the cause of the failure, the canal must be instrumented to sizes that may jeopardize the structural integrity of the root and the survivability of the tooth.

Also, in some cases, where the root filling includes a carrier that cannot be softened, its removal may not be possible, necessitating a surgical approach to the case.

Martin Trope, DMD, was born in Johannesburg, South Africa, where he received his BDS degree in dentistry in 1976. From 1976 to 1980, he practiced General Dentistry and Endodontics. In 1980, he moved to Philadelphia to specialize in Endodontics at the University of Pennsylvania. After graduating as an Endodontist he continued at the University of Pennsylvania as a faculty member until 1989 when he became Chair of Endodontology at Temple University, School of Dentistry. In 1993, Dr. Trope accepted the JB Freedland Professorship in the Department of Endodontics, UNC at Chapel Hill. Named in honor of one of the founding fathers of Endodontics, the Freedland Professorship recognizes significant contributions to the specialty. In 2014, he was awarded the Jens Ove Andreasen Lifetime Achievement Award by the International Association of Dental Traumatology. Dr. Trope is Clinical Professor, Department of Endodontics, University of Pennsylvania. He is also in private practice.

Dr. Klaus Lauterbach studied dentistry at Ruprecht-Karls University of Heidelberg, Germany. He focuses on endodontic treatment, diagnosis and therapy of parafunctional disease, and restorative dentistry. Dr. Lauterbach has lectured and held workshops on endodontic treatment since 2007. He is a certified member of the German Society of Endodontics and Traumatology and the European Society of Endodontics. He is also a member of the German Society of Implantology, the German Society of Computerized Dentistry, and the German Society of Parafunctional Disease. Dr. Lauterbach now operates a private practice near Heidelberg, Germany, with treatment limited to endodontics.

Gilberto Debelian, DMD, PhD, completed his specialization in Endodontics from the University of Pennsylvania in 1991 and received the Louis I. Grossman student award in Endodontics. He has taught as a clinical instructor and associate professor at the endodontic program at University of Oslo (UIO), Norway from 1991 to 2010. He was an adjunct visiting professor at the postgraduate program in endodontics, University of North Carolina in Chapel Hill from 2006 to 2015. He concluded his PhD studies at UIO in 1997, which gave him two scientific awards from the European Society of Endodontology (ESE) and from the Norwegian Dental Association both in 1997. He is an adjunct visiting professor at the postgraduate program in Endodontics at University of Pennsylvania. Dr. Debelian maintains a private practice limited to endodontics and is the director of the advanced endodontic microscopy center – ENDO INN in Oslo, Norway. Dr. Debelian has authored seven chapters in books about Endodontics and one book in Endodontics, and written more than 80 scientific and clinical papers.

Disclosure: Dr. Trope is a paid consultant for Brasseler. Drs. Lauterbach and Debelian do not have a financial interest in sales from Brasseler.

28 Endodontic practice

A previously published article in Endodontic Practice US introduces instruments with adaptive cores in order to clean the canal in all dimensions with minimal removal of dentin. (Learn more by visiting http://www.endopracticeus.com/clinicalarticles/three-dimensional-instrumentationreaching-next-level-endodontics.)

These instruments are the XP-3D Shaper™ and XP-3D Finisher™ (Brasseler USA®) that work together to maximally clean the canal with minimal dentin removal. The design of these instruments also makes them perfect for retreatment.

The XP-3D Shaper The core of the Shaper file has a diameter of 0.30 mm at the tip and 0.01 taper (#30/01).

The small taper makes the file highly flexible and resistant to cyclic fatigue (Figure 1), enabling the file to be used at high speed without the fear of fracture. Speeds of 1,000 rpm to 2,500 rpm are especially useful for retreatment purposes. Critical for retreatment, the file has a Booster Tip (BT) that allows it to move into spaces as small as 15/02 or 10/04 (Figure 2).

When the initial treatment is done with round files, there is inevitably space available in the bucco-lingual dimension of the canal that is not round (Figure 3).

These non-round areas are the path that the fine tip of the Booster Tip will penetrate and proceed into the canal.

At room temperature, the file has a slight serpentine shape. When it reaches body Volume 13 Number 1

TECHNOLOGY

Figure 2: SEM picture of the Booster Tip. (top) The first 0.25 mm comes to a sharp point and is non-cutting.

This allows the file to enter extremely small spaces between the GP and canal wall. View looking down at the BT tip shows that the tip is extremely small and is used to glide down the canal. Cutting starts 0.25 mm from the tip at a diameter of 0.15 mm

Figure 4: Left side represents traditional files that take up the entire space of the canal so will push GP and debris into the irregularities of the canal, while the right side shows the core is small and flexible enough to wrap around the GP and remove it without pushing it laterally

temperature in the canal, the file stiffens enabling it to move down the canal and also cut dentin, if required. The combination of the extreme flexibility of the file plus the serpentine shape results in the file moving into the path of least resistance so that it will find the unfilled areas of the canal and move down those “least resistant” pathways.

Now we have a file with a very small core diameter that will not take up the entire canal, and the serpentine shape will allow the material to be removed while staying within the “hollow” core of the file and thus not be pushed laterally in the canal.

As previously mentioned, round files cannot reach non-round areas in the canal.

Thus, in most of these cases, there is space in some part of the canal that has not been touched or filled (Figure 3). This space is the path of least resistance into which the Shaper will move while at the same time wrapping Volume 13 Number 1

Figure 3: Typical view of a GP-filled canal after instrumentation with a typical round file. The non-round parts of the canal are not cleaned and are obstructed with dentin and debris. Thus, the GP and sealer do not fill the areas. These are areas of least resistance that will be penetrated by the Booster Tip of the XP-3D file to start the GP removal. Once the canal is entered, the serpentine shape of the instrument will wrap around the GP and pull it out of the canal

Figure 5: Illustration of the entire gutta-percha core material removed with the use of the XP-3D Shaper. The serpentine shape of the instrument facilitates the removal of the entire core at once. (Courtesy Dr. K. Lauterbach)

around the core material and pulling it out via its “empty” core (Figures 4 and 5).

From a retreatment point of view, this file is ideal for removing the previous core filling material while not creating more debris and difficulty in disinfecting the failed previous root canal (Figures 4 and 5). However it does not have the ability to clean the very irregular parts of the canal or debris and gutta percha that may be within the irregularities from the previous primary root canal instrumentation and root filling. Here the addition of the XP-3D Finisher R is required to clean the canal maximally before the canal is obturated for the second time.

XP-3D Finisher R (retreatment) The XP-Finisher has a core diameter of No. 25 with no taper (00). When at body temperature, it will change shape to a sickle at the last 10 mm, giving it a capacity of

Figure 6: The dimensions of the XP-3D Finisher are 0.25 diameter and 0.00 taper (top). When at body temperature in the austenite phase (bottom), the last 10 mm of the instrument achieves a sickle shape with a depth of 1.5 mm.

Thus when spinning, it can reach 300, and if the sickle is compressed, the tip can expand to 600

No. 300 (Figure 6) when spinning and no resistance is met; but when compressed inside the canal, the tip has the capacity of up to No. 600.

After the initial removal of the gutta-percha core material, especially with traditional files, Endodontic practice 29

TECHNOLOGY

Figure 7: Depiction of typical remnants of GP, sealer, and debris after the initial removal of the core GP from the root canal. The remnants are particularly present around any curvature in the canal

Figure 9: The Finisher R is used after files have been used to remove the gutta-percha core. Note the additional gutta percha removed after the canal was deemed to have been sufficiently cleaned. (Image courtesy of Dr. Jorge Vera)

there is inevitably gutta percha, sealer, and debris on the walls of the canal particularly around any curvature in the canal and, as already mentioned, in the irregularities of the canal (Figure 7).

In order to more effectively remove these remnants, a XP-Finisher R has been developed. This instrument is identical to the XP-Finisher except that the core file is size 30/00 rather than size 25/00 (Figure 8).

This gives the instrument more strength to dislodge sticky remnants while contacting the canal walls than the 25/00 that needs to (only) remove biofilm and microbes that should be easier to dislodge. Thus, after removal of the core gutta-percha point with the XP-3D Shaper, the XP-Finisher R is used for 60 seconds to dislodge remaining remnants that have stuck to the canal wall and irregularities. Most practitioners are amazed at the amount of debris that is seen after what they considered to be a clean canal ready for re-obturation (Figure 9).

30 Endodontic practice

Figure 8: Shows the slightly thicker core of the Finisher R (top) compared to the Finisher (bottom)

Figure 10: Sixty-nine percent reduction of debris found with the use of the XP-3D Finisher R after standard retreatment with round files. (Alves, et al., 2016).

These two instruments in combination offer tremendous advantages over the traditional round files.

Studies have shown that the Finisher is able to remove a remarkable amount of remaining gutta percha and debris after the first attempt with traditional files. Figure 10 shows the diagrammatic results from one such study.

Case report The following case illustrates a retreatment performed by Dr. Klaus Lauterbach using the adaptive core instruments.

The patient presented symptomatic with a poorly filled root canal on the lower left molar with evidence of posttreatment disease.

Figure 11: Preoperative radiograph of failing root canal

Figure 11 shows the preoperative radiograph of the failing root canal.

Volume 13 Number 1

Figure 13: Entry path was made with a thin ultrasonic tip and the tip of the XP-3D Shaper placed

Figure 14: Gutta percha is easily removed from the canal using the XP-3D instrument at high speed

Figure 15: The canal is further cleaned with the XP-Finisher R for 60 seconds (left), and then the patient returned after 1 week for obturation (right)

Access was prepared through the crown in order that the adaptive files could freely enter each canal (Figure 12).

An entry path was made into the guttapercha with a thin ultrasonic tip and the tip of the XP-3D Shaper placed into this path (Figure 13).

Using the XP-3D instrument at high speed (1,000 rpm to 2,500 rpm), the gutta percha is easily removed from the canal in thin strings wrapped around file or within the coils of the file (Figure 14).

The canal is further cleaned with the XP-Finisher R for 60 seconds, and calcium hydroxide is placed with a lentulo-spiral instrument (not shown here). Then the patient was asked to return after 1 week for obturation. The patient returned after 1 week asymptomatic, and the canal was filled with cold hydraulic obturation bioceramic GP and sealer (Figure 15).

The postoperative radiograph shows a well filled root canal with evidence of sealer in the isthmus of the mesial canals (Figure 16).

Summary Retreatment has been a challenging procedure for a number of reasons. First, the first instrumentation usually has dictated the remaining dentin in the canal that usually must be further reduced in order to adequately disinfect. Traditional instruments are poorly designed for retreatment because instead of removing old filling material, they usually spread the material into previously Volume 13 Number 1

unfilled parts of the canal making disinfection more difficult and removal of a large amount of dentin inevitable.

The XP-3D instruments are perfectly designed for retreatment. The XP-3D Shaper is able to locate areas of least resistance due to the Booster Tip and extreme flexibility.

Once a path has been found, the adaptive core of the instrument is able to extract the core gutta percha from the canal without moving it laterally, thus saving valuable dentin and maintaining the strength of the tooth before retreatment. The XP-3D Finisher R file is stiff enough to remove remaining GP, debris, and biofilm but not stiff enough to change the shape of the canal or remove noticeable dentin, thus maintaining the strength of the tooth before the root canal was started. Thus, these two instruments in combination offer tremendous advantages over the traditional round files. EP

REFERENCES 1. Alves F, Marcelano-Alves MF, Sousa JC, et al. Removal of root canal filling in curved canals using either reciprocation single- or rotary multi-instrument system and a supplementary step with the XP-endo Finisher. J Endod. 2016;42 (7):1114-1119.

2. Alves FR, Andrade-Junior CV, Marceliano-Alves MF, et al.

Adjunctive steps for disinfection of the mandibular molar root canal system: a correlative bacteriologic, microcomputed tomography, and cryopulverization approach. J Endod. 2016;42(11):1667-1672.

3. Azim AA, Aksel H, Zhuang T, et al. Efficacy of 4 irrigation protocols in killing bacteria colonized in dentinal tubules examined by a novel confocal laser scanning microscope analysis. J Endod. 2016;42(6):928-934.

4. Azim AA, Piasecki L, da Silva Neto UX, Cruz ATG, Azim KA. XP Shaper, a novel adaptive core rotary instrument:

Figure 16: Postoperative radiograph

microcomputed tomographic analysis of its shaping abilities. J Endod. 2017;43(9):1532-1538.

5. Bao P, Shen Y, Lin J, Haapasalo M. In vitro efficacy of X-endo Finisher with 2 different protocols on biofilm removal from apical root canals. J Endod. 2017;43(2):321-325.

6. Bayram HM, Bayram E, Ocak M, Uygun AD, Celik HH. Effect of ProTaper Gold, Self-Adjusting File, and XP-endo Shaper instruments on dentinal microcrack formation: a micro-computed tomographic study. J Endod. 2017; 43(7):1166-1169.

7. De-Deus G, Belladonna FG, Silva EJ, et al. Micro-CT evaluation of non-instrumented canal areas with different enlargements performed by NiTi systems. Braz Dent J. 2015;26(6):624-629.

8. Metzger Z. From files to SAF: 3D endodontic treatment is possible at last. Alpha Omegan. 2011;104(1-2):36-44.

9. Paqué F, Al-Jadaa A, Kfir A. Hard-tissue debris accumulation created by conventional rotary versus self-adjusting file instrumentation in mesial root canal systems of mandibular molars. Int Endod J. 2012;45(5):413-418.

10. Paqué F, Balmer M, Attin T, Peters OA. Preparation of oval-shaped root canals in mandibular molars using nickeltitanium rotary instruments: a micro-computed tomography study. J Endod. 2010;36(4):703-707.

11. Peters OA, Laib A, Rüegsegger P, Barbakow F. Threedimensional analysis of root canal geometry using highresolution computed tomography. J Dent Res. 2000; 79(6):1405-1409.

12. Trope M, Serota K, Debelian G. Three-dimensional instrumentation — reaching the next level in endodontics.

Endodontic Practice US. 2017;10(3):14-20.

13. Wolf TG, Paqué F, Zeller M, Willershausen B, BriseñoMarroquín B. Root canal morphology and configuration of 118 mandibular first molars by means of microcomputed tomography: an ex vivo study. J Endod. 2016; 42(4):610-614.

Endodontic practice 31

TECHNOLOGY

Figure 12: Access was prepared through the crown so that the adaptive files could freely enter each canal

INDUSTRY NEWS Oral-care probiotics by ProBiora Health™ shown to be effective in maintaining overall health

Glidewell announces dynamic lineup for the Guiding Leaders Summit 2020

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Glidewell, an industry-leading provider of dental laboratory services, products, technologies, and clinical education, announced its lineup for the Guiding Leaders Summit, which takes place April 24–25, 2020, at the Paséa Hotel & Spa in Huntington Beach, California. The 2-day summit is for all women in dentistry and will offer a wide range of courses that are intended to provide attendees the latest training in three key areas: clinical dentistry, leadership development, and interpersonal wellness.

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To see the summit overview, visit guidingleaders.com.

SS White rebrands its endodontic file lines The Pankey Institute appoints Dr. Lee Ann Brady as President and CEO Dr. Lee Ann Brady has accepted the position of President and CEO of The Pankey Institute, adding to her existing responsibilities as Director of Education. During the past 2 years, Dr. Brady led unprecedented growth at this 50-year-old nonprofit institute.

Under her tenure as Director of Education, the number of first-time participants in a Pankey program has more than doubled, attendance in their “Essentials” core curriculum has doubled, and attendance at its Annual Symposium has tripled.

The nonprofit institute in Key Biscayne, Florida, is dedicated to helping dental professionals master advanced technical skills, practice management, and nurture a positive philosophy toward life and practice. Over 30,000 dentists, dental laboratory technicians, and specialists from 44 nations have attended its courses and have provided exceptional care to over 54 million patients worldwide.

To learn more about The Pankey Institute, visit the website at www.pankey.org.

32 Endodontic practice

New names. Same quality. Linking branding to treatment objectives and technique For 175 years, SS White has made a name for itself by providing high-quality and dependable dental solutions. Today, we continue to serve the needs of clinicians with products focused on a conservative, holistic approach.

The DCTaper files (formerly VTaper) are the same anatomically designed endodontic files that provide greater safety, strength, and flexibility you’ve trusted for years. The “DC” name stands for Dentin Conservation and more accurately reflects the main benefit, which is preservation of as much of the natural tooth as possible. This is the compelling reason for the name change; DCTaper provides a clearer indication of the treatment objectives.

The rebranded products are made in the U.S.A. and meet the strict quality controls that have earned the respect of endodontists and dentists around the world.

For more information, visit sswhitedental.com.

Volume 13 Number 1

Dr. John Rhodes demonstrates a methodical approach using reciprocating nickel-titanium instruments

C

urved and sclerosed canals can raise difficulties for the operator during root canal treatment resulting in iatrogenic errors.

In this case, challenging root canal anatomy in a maxillary molar (UR6) was successfully negotiated using a methodical approach and reciprocating nickel-titanium instruments.

Clinical examination A 56-year-old man was referred for root canal treatment of his UR6 after his general dentist had been unable to locate or negotiate sclerosed canals in the painful tooth.

Intraorally, there were no swelling, sinus tracts, visible cracks, or increased periodontal pocketing. The tooth was restorable, but the existing amalgam restoration was defective. The tooth was nonvital to sensitivity testing with Endo-Ice® (Coltene).

Radiographic assessment using a paralleling periapical radiograph (Rinn, Dentsply Sirona) showed a large amalgam restoration distally with poor marginal integrity. There was evidence of access cavity preparation and removal of dentin overlying the distobuccal (DB) canal. The DB and palatal canals appeared patent, but the mesio-buccal (MB) canals had not been located or negotiated, and the MB root was significantly curved.

There was evidence of periapical radiolucency. There were no discernible signs of periodontal disease or gross caries.

Diagnosis A necrotic UR6 associated with periapical periodontitis.

Treatment options Sensible treatment options in this case include: • Nonsurgical root canal treatment, followed by placement of a cuspcoverage restoration • Extraction only or replacement with an implant or bridge John Rhodes, BDS(Lond), FDS RCS(Ed), MSc, MFGDP(UK), MRD RCS(Ed), is a specialist in endodontics, the author of textbooks and numerous papers, and owner of The Endodontic Practice Poole and The Endodontic Practice Dorchester. He lectures and teaches on endodontics nationally.

Volume 13 Number 1

Educational aims and objectives

This article aims to demonstrate how a challenging root canal anatomy in a maxillary molar (UR6) was successfully negotiated using a methodical approach and reciprocating nickeltitanium instruments.

Expected outcomes

Endodontic Practice US subscribers can answer the CE questions on page 39 to earn 2 hours of CE from reading this article. Correctly answering the questions will demonstrate the reader can: • Recognize when the use of straight-line access is advisable.

• Identify tools with which to estimate working length.

• Recognize some possible techniques to establishing a glide path.

• Realize the essential component of the development of a reproducible glide path.

• Realize that in some patients micro-cracking of the root dentin can be induced during mechanical preparation.

Figure 1: Preoperative radiograph

• Extraction and replacement with an implant should be feasible but may require bone augmentation.

The natural tooth was eminently restorable, and a good root filling complimented with a well-fitting crown could be expected to function as well as an implant-supported crown for significantly less cost and surgery time (Torabinejad, et al., 2007; Hannahan and Eleazer, 2008; Pennington, et al., 2009).

Treatment After discussing all the available options, the patient decided to have UR6 root filled.

Nonsurgical root canal treatment was planned for a single visit. Following profound local anesthesia with articaine (Septodont), single tooth isolation was achieved with rubber dam and a No. 14 clamp. The existing restoration and caries were completely removed and the pulp floor refined with a Tungsten Carbide LN bur (Dentsply). A size 2 bur was used under

Figure 2: A large LN bur compared to a standard round bur.

The narrow neck allows visualization of the cutting tip

the operating microscope to trough along the isthmus from MB1, which revealed a further two orifices (MB2 and MB3).

Straight-line access Straight-line access is advisable when using rotary or reciprocating instruments.

Removing calcified material from the coronal aspect makes transition deeper into the canal system easier, reduces stress on instruments, and allows rapid penetration of irrigant into the canal earlier during preparation. (Berruti, et al., 2004) The orifice of each canal was explored to a depth of a few millimeters with a size 6 and 10 FlexoFile® (Dentsply Sirona) and then flared with a ProTaper® SX (Dentsply Sirona) instrument, brushing against the bulkiest wall of the canal and working to a depth approximately half the canal length as estimated from the preoperative radiograph. Thorough irrigation with 3% sodium hypochlorite was Endodontic practice 33

CONTINUING EDUCATION

A clinical case of a necrotic UR6 associated with periapical periodontitis

CONTINUING EDUCATION used throughout to remove debris. It was apparent that the MB2 communicated with the MB1, and therefore, it would not be necessary to enlarge this further.

Working-length estimation All root lengths were estimated with a multi-frequency apex locator (Elements™ Diagnostics Unit, SybronEndo) and a size 6 FlexoFile with a small amount of Glyde™ (Dentsply) on the instrument. As consistent and steady zero readings were obtained, a diagnostic radiograph was not deemed necessary.

Figure 3: Microscope examination of the pulp floor after caries removal and orifice location. There is an isthmus running from the MB1 and the DB canals. A superficial crack can be seen on the distal aspect

Figure 4: Flaring of the orifices of the MB canals revealed that the MB1 and MB2 interconnected

Establishing a glide path The buccal canals were fine, and initially only a size 6 FlexoFile could be passed to the working length after coronal flaring. With a watch-winding action, this was enlarged to a size 10 FlexoFile using copious irrigation with 3% sodium hypochlorite. Once at the working length, the instrument was manipulated with small amplitude (2 mm-3 mm) vertical movements until it would reproducibly pass to the working length. This was particularly relevant in the DB canal, which had an acute curve in the apical tip. The working length was reconfirmed with the apex locator. A small WaveOne® Gold (Dentsply Sirona) reciprocating instrument was then used to enlarge the preliminary glide path to the full working length. This instrument has an average taper of 7% and a tip size 20.

WaveOne Gold instruments have a reciprocating action and have to be used in a dedicated electric motor. In this case, the X-Smart iQ cordless motor was used, which is controlled from a dedicated app on an iPad®. The app records and displays realtime torque monitoring, so if excess stress is incurred, the instrument auto-reverses with visual and audible warnings.

Preparation and tapering Rapid tapering of the primary root canals was completed with WaveOne Gold (Dentsply Sirona) instruments, always working through a puddle of sodium hypochlorite on the pulp floor and patency confirmed with a size 10 FlexoFile. A single Primary WaveOne Gold instrument (average taper 7% and tip size 25) was used in all canals apart from the palatal, which was finished using a medium WaveOne Gold (average taper 6% and tip size 35).

Disinfection A heated 3% solution of sodium hypochlorite was used to disinfect the prepared root canals. This was agitated using a freely vibrating Irrisafe™ tip (Satelec) inserted 2 mm from the working length and an 34 Endodontic practice

Figure 5: The X-Smart iQ cordless motor

EndoActivator® (Dentsply) with a Red tip using a pumping action.

Obturation The case was obturated using a vertically compacted gutta-percha technique with heated pluggers, AH Plus® sealer (Dentsply Sirona), and Obtura (Obtura Spartan) thermoplasticized gutta percha to backfill.

Coronal seal The pulp floor and coronal aspect of the root canals were sealed with Smart Dentin Replacement (SDR - Dentsply Sirona) a bulk fill, flowable composite (this material will cure to a depth of 4 mm in bulk sections). The tooth was then temporized with resin modified glass ionomer (Fuji IX®). The general dental practitioner would complete restoration with a core and full coverage crown.

Postoperative paralleling radiographs were exposed at two angles to confirm a homogenous seal. Review was scheduled for 6 months.

Discussion The risk of blocking the canal during preparation is probably greater when the canal is fine or sclerosed because rotary or reciprocating instruments machine a comparatively greater surface area of the root canal wall and therefore create more dentin chips. The chips and smear can block the canal or pack into the flutes of the instrument and increase the risk of tip fracture. The volume of available irrigant is also reduced resulting in smear “clumping.” Copious irrigation during preparation and recapitulation

Figure 6: WaveOne Gold instruments small, primary, and medium. The primary instrument can be used to prepare 80% of root canals. It is possible to pre-bend the instruments, which can be very helpful

with a fine file can be used to avoid this happening.

WaveOne Gold instruments are manufactured with heat-treated M-wire. In-house testing by Dentsply Sirona has shown that cyclic fatigue resistance has been improved by 50% compared with WaveOne and 100% more than most standard rotary systems.

WaveOne Gold instruments are 80% more flexible than WaveOne. Despite superior metallurgy, it is essential to create a reproducible glide path for nickeltitanium instruments to follow (Nahmias, et al., 2013; Kubde, 2012). The glide path reduces the chance of instrument fracture as a result of cyclic or torsional fatigue or when the tip becomes locked in the canal.

(Sattapan, et al., 2000; Patiño, et al., 2005; Plotino, et al., 2009).

Flexible stainless steel instruments such as FlexoFiles can be used to scout the canals and establish patency followed by a narrow taper rotary or reciprocating instrument to create the glide path. In this case, FlexoFiles and a small WaveOne Gold instrument were used. The ProGlide® (Dentsply Sirona) is a rotary instrument that has been designed specifically for this purpose and has been shown to be one of the most efficient means of preparing a glide path (Van der Vyver, 2015).

There is evidence that micro-cracking of the root dentin can be induced during mechanical preparation (Yoldas, et al., 2012).

This appears to be more prevalent with rotary techniques and when larger sizes or tapers are used. Generally, the canals should be tapered sufficiently to allow adequate irrigant penetration but avoid excessive dentin Volume 13 Number 1

Volume 13 Number 1

Figure 7: The pulp floor following obturation

Figure 8: Smart Dentin Replacement (SDR) was used to seal the coronal aspect of the root canals and pulp floor

Figure 9: Paralleling radiograph showing homogenous completed obturation

Figure 10: The mesial canals all merge through a single isthmus

minimal level of evidence for considering one versus two appointments in nonsurgical endodontics. Indeed, meta-analysis has shown that a single-visit approach (as used by many endodontists) has no bearing on prognosis, outcome, or postoperative pain (Ng, et al., 2011). This case was therefore completed in a single visit.

phenol and calcium hydroxide in the treatment of infected root canals. Endod Dent Traumatol. 1985;1(5):170-75

Conclusion In this case, curved and sclerosed canals in a maxillary molar were managed using WaveOne Gold instruments. The development of a reproducible glide path was essential. The operator should not be put off by the preoperative radiographic appearance or lack of canal definition on a CBCT image. However, often the canals are not as fine as they seem, so by using a methodical approach to preparation, these anatomical challenges can be overcome. EP REFERENCES 1. Ahmad M, Pitt Ford TJ, Crum LA. Ultrasonic debridement of root canals: acoustic streaming and its possible role. J Endod. 1987;13(10):490-499.

2. Berutti E, Negro AR, Lendini M, Pasqualini D. Influence of manual preflaring and torque on failure rate of the ProTaper rotary instruments. J Endod. 2004;30(4):228-230.

3. Burleson A, Nusstein J, Reader A, Beck M. The in vivo evaluation of hand /rotary/ultrasound instrumentation in necrotic human molars. J Endod. 2007;33(7):782-787.

4. Byström A, Sundqvist G. Bacteriologic evaluation of the efficacy of mechanical root canal instrumentation in endodontic therapy. Scand J Dent Res. 1981;89(4):321-328.

5. Byström A, Sundqvist G. Bacteriologic evaluation of the effect of 0.5 percent sodium hypochlorite in endodontic therapy.

Oral Surg Oral Med Oral Pathol. 1983;55: 307-312.

6. Byström A, Sundqvist G. The antibacterial action of sodium hypochlorite and EDTA in 60 cases of endodontic therapy.

Int Endod J. 1985;18:35-40.

7. Byström A, Claesson R, Sundqvist G. The antibacterial effect of camphorated paramonochlorophenol, camphorated

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

2008;34(11):1302-11305 9. Hargreaves KM. Single-visit more effective than multiple-visit root canal treatment. Evid Based Dent. 2006;7(1)13-14.

10. Kubde R, Saxena A, Chandak M, Bhede R, Sundarkar P. Creating endodontic glide path: A short review. Int J Dent.

2012;4(1):40-41.

11. Liu R, Kaiwar A, Shemesh H, et al. Incidence of apical root cracks and apical dentinal detachments after canal preparation with hand and rotary files at different instrumentation lengths. J Endod. 2011;39:129-132.

12. Nahmias Y, Cassim I, Glassman G. Own the canal – the importance of a reproducible glide path. Oral Health.

2013;5:74-82.

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

14. Patiño PV, Biedma BM, Liébana CR, Cantatore G, Bahillo JG. The influence of manual glide path on the separation rate of NiTi rotary instruments. J Endod. 2005;31:114-116.

15. Pennington MW, Vernazza CR, Shackley P, et al. Evaluation of the cost-effectiveness of root canal treatment using conventional approaches versus replacement with an implant. Int Endod J. 2009;42:874-883.

16. Peters LB, van Winkelhoff AJ, Buijs JF, Wesselink PR. Effects of instrumentation, irrigation and dressing with calcium hydroxide on infection in pulpless teeth with periapical bone lesions. Int Endod J. 2002; 35, 13-21.

17. Plotino G, Grande NM, Cordaro M, Testarelli L, Gambarini, G (2009). A review of cyclic fatigue testing of nickel-titanium rotary instruments. J Endod. 35: 1469-76.

18. Sattapan B, Nervo GJ, Palamara JE, Messer HH. Defects in rotary nickel titanium files after clinical use. J Endod.

2000;26(3):161-165.

19. Sjögren U, Figdor D, Spångberg L, Sundqvist G. The antimicrobial effect of calcium hydroxide as a short-term intracanal dressing. Int Endod J. 1991;24(3):119-125.

20. Torabinejad M, Anderson P, Bader J, et al. Outcomes of root canal treatment and restoration, implant-supported single crowns, fixed partial dentures and extraction without replacement: a systematic review. J Prosthet Dent.

2007;98(4):285-311.

21. van der Sluis LW, Versluis M, Wu MK, Wesselink PR. Passive ultrasonic irrigation of the root canal: a review of the literature.

Int Endod J. 2007;40:415-426.

22. Van der Vyver PJ, Paleker F, Jonker CH. Comparison of preparation times of three different rotary glide path instrument systems. S Afr Dent J. 2015;70(4):144-147.

23. Yoldas O, Yilmaz S, Atakan G, Kuden C, Kasan Z. Dentinal microcrack formation during root canal preparations by different NiTi rotary instruments and the self-adjusting file. J Endod. 2012;38(20:232-235.

Endodontic practice 35

CONTINUING EDUCATION

removal (Liu, et al., 2011). WaveOne Gold instruments are operated in a reciprocating motion, which reduces stress. They have progressive tapers, but the average apical taper has been reduced from equivalent WaveOne instruments, and the manufacturer has introduced an intermediate size medium file with tip size 35.

Mechanical preparation alone can reduce the bacterial load in an infected root canal (Byström and Sundqvist, 1981), but sodium hypochlorite in a concentration of at least 1% is required to kill any remaining bacteria (Byström and Sundqvist, 1983). Bacteria in a necrotic root canal system such as this case are present in planktonic form and as a complex biofilm in which bacteria are surrounded by matrix on the walls of the canals and can be difficult to remove.

Irrigants must therefore be agitated to break up these bacterial aggregations. It is possible to achieve acoustic microstreaming when an ultrasonic file oscillates freely in the root canal (Ahmad, et al., 1987), and the forces created by the turbulence may disrupt biofilm. Passive ultrasonic irrigation (PUI) utilizes a small file oscillating freely in the root canal to induce acoustic microstreaming, and in this case, PUI and agitation with the EndoActivator were used. Compared with traditional syringe irrigation, PUI removes more organic tissue, planktonic bacteria, and dentin debris from the root canal (Burleson, et al., 2007; van der Sluis, et al., 2007).

It can be difficult to ensure adequate irrigant exchange at the apex of fine, long, or highly curved canals. The primary canals must be sufficiently tapered to allow sufficient volume of irrigant to be introduced into the root canal system. Conservative tapering of the canal is generally not a problem with modern nickel- titanium systems.

The chelating agent 17% EDTA is sometimes used as a final rinse during irrigation (Byström and Sundqvist, 1985). It is used to remove smear and has a positive benefit on outcome in retreatment cases; however, this does not seem to be the case with primary treatment (Ng, et al., 2011).

In a two-visit approach, the canals are medicated after preparation and disinfection with calcium hydroxide for 7 days. This has been shown to be an effective means of producing bacteria-free canals (Byström, Claesson, Sundqvist, 1985; Sjögren, et al., 1991). However, more recently, Peters, et al.

(2002), showed that calcium hydroxide and sterile saline slurry limits but does not totally prevent regrowth of endodontic bacteria.

Hargreaves (2006) in a systematic review of the literature reported that multiple visits with calcium hydroxide treatment did not improve upon clinical outcome, and there was a

CONTINUING EDUCATION

Treatment of maxillary first premolars with three root canals (case report) Drs. Yuriy Riznyk, Svitlana Riznyk, and Khrystyna Sydorak discuss how modern instrumentation can make it more viable to tackle rare and complex root canal systems

T

he development of equipment and instrumentation techniques has made it possible to solve difficult clinical cases in endodontics (Berutti, et al., 2009). However, irrespective of the continuous improvement of technology, the profound knowledge of the internal anatomy of the pulp chamber and the root canal system remains crucial to increase the efficiency and, subsequently, the rate of clinical success of endodontic treatment (Vertucci, 2005; Baratto, Filho, et al., 2009; Fava, 2001).

The incomplete instrumentation, irrigation, and poor quality of obturation of the root canal system are the main causes of endodontic failure (Leonardo, 1998). Song, et al. (2011), reported that 11.7% of possible causes of failure in the previous root canal treatment of upper premolars were missed root canals.

Among permanent teeth, the roots of maxillary first premolars often have two conical roots — i.e., one buccal and one palatal root, which may present root fusion.

The buccal root may be further subdivided into two, causing the tooth to have three canals: a palatal, a distobuccal, and a mesiobuccal canal (Pécora, et al., 1992; Awawdeh, et al., 2008).

The incidence of one root canal does not exceed 31% of all cases; two root canals varies from 67% to 72% (Carns and Skidmore, 1983; Bellizi and Hartwell, 1985; Vertucci and Gegaulf, 1979; Sert and Bayirli, 2004). Carns and Skidmore (1973) found 6% of maxillary first premolars to have

Educational aims and objectives

This article aims to explore how the internal anatomy of the pulp chamber and the root canal system remains crucial to increase the efficiency and, subsequently, the rate of clinical success of endodontic treatment.

Expected outcomes

Endodontic Practice US subscribers can answer the CE questions on page 39 to earn 2 hours of CE from reading this article. Correctly answering the questions will demonstrate the reader can: •

Identify some of the main causes of endodontic treatment failure.

•

Recognize the use of the T-shaped access cavity modification as an approach to root canals.

•

Recognize the use of computed tomography as an additional diagnostic tool as useful to detect anatomical variations.

•

Realize the importance of optical magnification, dyes, and ultrasound tips to enhance the visualization of the pulp chamber and extra canal orifices.

Yuriy Riznyk, DMD, PhD, is an assistant in the therapeutic dentistry department at Danylo Halytsky Lviv National Medical University, Lviv, Ukraine; and co-winner of the Ukrainian Endodontic Association contest “Art of Endodontic Treatment” in 2012.

three canals, all of which were present as one canal in each of three roots. Vertucci and Gegaulf (1979) found 5% of maxillary first premolars to have three canals: 0.5% existed as three canals in a single root; 0.5% existed as two canals in one root and one canal in a second root; and 4% existed as one canal in each of three separate roots.

It is worth mentioning that visualization of three-canalled maxillary premolars on preoperative radiographs can often be difficult.

Thus, a careful examination of several preoperative radiographs or the use of computed tomography as an additional diagnostic tool can be useful to detect anatomical variations (Sachdeva, et al., 2008; de Paula, et al., 2013).

The use of the T-shaped access cavity modification may be helpful for correct approach to all of the root canals (Balleri, et al., 1997). Optical magnification (BaldassariCruz, et al., 2002; Yoshioka, et al., 2002), dyes, and ultrasound tips are important aids in endodontics because these facilitate locating canals and approaching them correctly.

Svitlana Riznyk, DMD, PhD, is head of the department of therapeutic dentistry in Lviv Medical Institute, Lviv, Ukraine.

Case report 1 (Figures 1, 2, and 3)

Khrystyna Sydorak, DMD, works at the Shupyk National Medical Academy of Postgraduate Education.

A 28-year-old male patient with a noncontributory medical history applied to the clinic with the chief complaint of spontaneous

36 Endodontic practice

pain in the upper right region of the jaw for the previous 2 days.

On clinical examination, a deep carious lesion affecting almost the whole crown was seen in tooth UR4. Vitality testing of the involved tooth with cold testing caused an intense lingering pain. Percussion test was negative. Investigations for swelling, sinus tract, and periodontal involvement were negative. A preoperative radiograph (Figure 1) revealed radiolucency on the occlusaldistal surfaces of the crown, approaching the pulp space and vague two separate roots

Figure 1: Initial radiograph of UR4 tooth showing caries and two vague separate roots Volume 13 Number 1

CONTINUING EDUCATION

Figures 2 and 3: Post-obturation radiographs showing UR4 with three separate root canals — two buccal and one palatal

in the first upper premolar. A diagnosis of symptomatic irreversible pulpitis was made judging by the clinical and radiographic examination, and conservative endodontic treatment was recommended.

After local anesthesia with 4% Ubistesin 1:100000 (3M ESPE) and rubber dam isolation of the operative area, pulp chamber access was performed using a long neck round-shaped drills, cone-shaped drills with nonaggressive tip, and ultrasonic tips.

While preparing the access to the root canal orifices, care was taken to save as much healthy tissue as possible. The examination of the pulp chamber floor was performed with the DG16 endodontic probe and dye under optical magnification. The outline of the access cavity was modified as suggested by Balleri, et al., (1997). The pulp chamber was rinsed with 6% sodium hypochlorite. The canals were negotiated with a slightly bent 10 K-file (Dentsply Maillefer) using a watch-winding motion and slow pushing movements toward the apical constriction. The patency was established at working length with 10 K-file using I-PEX apex locator (NSK, Japan) and confirmed radiographically. The glide path was performed using size 15 and 20 K-files NITIFLEX® (Dentsply Maillefer). The instrumentation of the coronal third of the root was performed using the ProTaper Next™ XA (Dentsply Maillefer) instrument.

The rest of root canal system was prepared with XP-endo shaper (Schottlander). The preparation was completed with 35/.04 BT-Race (Schottlander). At each change of Volume 13 Number 1

instrument, the canals were irrigated with 2 ml of 6% sodium hypochlorite solution.

At the end of biomechanical preparation, 17% EDTA (Cercamed, Poland) was applied for 1 minute to remove smear layer, and the final washing was performed with copious volume of 6% sodium hypochlorite. The solutions were activated by XP-endo finisher (Schottlander) within 1 minute, applying slow, gentle longitudinal movements of 7 mm8 mm to cover the entire length of the canal.

Before the obturation, all canals were rinsed with sterile saline 0.9%.

The canals were partially dried with paper points and obturated by cold hydrodynamic obturation technique of gutta percha and premixed bioceramic obturation material TotalFill® (Schottlander).

The pulp chamber was cleaned to remove the excess of gutta percha and bioceramic sealer, and the tooth was temporarily restored with glass ionomer cement Fuji IX GP (GC UK). The patient was referred for the orthopedic treatment of UR4 tooth.

Case report 2 A 22-year-old female was referred to the clinic by the dentist after the previously initiated therapy with a history of symptomatic periapical periodontitis. Clinically, there was a cement filling at the occlusal-distal surface of the tooth UL4. The UL4 was not sensitive to cold testing. Investigations for swelling, sinus tract, and periodontal involvement were negative. Preoperative radiograph (Figure 4) revealed no periapical involvement of the periodontal ligament space and a vague

outline of two roots. The radiopaque matter was found in the root canals. Conservative endodontic treatment of UL4 was recommended.

Local anesthesia with 4% Ubistesin™ 1:200000 (3M ESPE) was performed before placement of rubber dam. The tooth was isolated, access was prepared, and the floor of the pulp chamber was examined with an optical magnification, dye, and endodontic probe DG 16. The residue of Ca(OH)2 paste was found in the two root canals. The third (mesio-buccal) root canal was revealed, and access cavity was modified. Three root canals were explored with size 10 K-file. The working lengths were estimated using an apex locator I-PEX (NSK UK) and then confirmed with a radiograph.

Two buccal canals were connected near the apical constriction, and the palatal canal was separate.

The root canal system was prepared with X1, X2, X3 ProTaper Next (Dentsply Maillefer) and stainless steel K-files (Dentsply Maillefer).

At each change of instrument, the canals were irrigated with 2 ml of 6% sodium hypochlorite solution. The master apical file in all canals was an ISO size 45.

Before the obturation 17% EDTA (Cercamed, Poland) and copious volume of 6% sodium hypochloride were used alternately, followed by the saline. The final washing was performed with 2% digluconate chlorhexidine for 10 minutes, followed by the saline. All of the solutions were activated with XP-endo finisher (Schottlander) within 1 minute.

Endodontic practice 37

CONTINUING EDUCATION

Figure 4: Initial radiograph of UL4 tooth showing two vague roots in maxillary first premolar

The canals were partially dried with paper points and obturated by cold hydrodynamic obturation technique with gutta percha and premixed bioceramic obturation material TotalFill (Schottlander).

Light-cured composite was used for the temporary sealing. The patient was referred for the orthopedic treatment of UL4.

Discussion An accurate diagnosis of the anatomy of the root canal system is a prerequisite for successful endodontic treatment (Aguiar, et al., 2010). The process of identifying and accessing root canals is particularly challenging in endodontic treatment of teeth with atypical canal configuration.

The radiographic signs that demonstrate the presence of anatomical variations must be considered as an important condition when planning the dental treatment (Vertucci, 2005). However, it should be noted that visualization of three canals in a maxillary premolar on preoperative radiographs could often be difficult, because the preoperative radiography gives a two-dimensional image of a three-dimensional object. Advanced diagnostic tools such as cone-beam computed tomography might give a more accurate picture of root canal morphology.

The access modification can be useful for an endodontist for easy and correct approach to every root canal.

Appropriate shaping and cleaning of the root canal system with proper instruments can improve the quality of root canal system cleaning (Adbam, et al., 2017; SanabriaLiviac, et al., 2017; Adbam, et al., 2016).

38 Endodontic practice

Figure 5: Post-obturation radiograph showing UL4 with two united buccal canals and one palatal canal

A profound knowledge of the internal anatomy of roots, correct diagnosis, and appropriate shaping and cleaning of the root canal system usually leads to the successful clinical outcome (Schäfer and Bossmann, 2001).

Conclusions Morphological variations of the root canal system should always be considered before beginning treatment. According to the literature, three root canals in the first upper premolar are found in 0.5-6% of cases. Thorough clinical examination and comprehensive analysis of angled radiographs are essential for the successful endodontic treatment. In daily practice, it is important to use an optical magnification, dyes, and ultrasound tips because these methods can enhance the visualization of the pulp chamber and extra canal orifices, and consequently, increase the clinical success of endodontic treatment. EP

REFERENCES 1. Adbam Azim A, Hacer Aksel, Tingting Zhuang, et al. Efficacy of 4 irrigation protocols in killing bacteria colonized in dentinal tubules examined by novel confocal laser scanning microscope analysis. J Endod. 2016;42(6):928-934.

2. Azim AA, Plasecki L, da Silva Neto UX, et al. XP-Shaper, A novel adaptive core rotary instrument: Micro-computed tomographic analysis of its shaping abilities. J Endod.

2017;43(9):1532-1538.

3. Aguiar C, Mendes D, Câmara A, Figueiredo J. Endodontic treatment of a mandibular second premolar with three root canals. JCDP. 2010;11(2):78-84.

4. Awawdeh L, Abdullah H, Al-Qudah A. Root form and canal morphology of Jordanian maxillary first premolars. J Endod.

2008;34(8):956-961.

5. Baldassari-Cruz LA, Lilly JP, Rivera EM. The influence of dental operating microscope in locating the mesiolingual canal orifice. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2002;93(2):190-194.

6. Balleri P, Gesi A, Ferrari M. Primer premolar superior com tres raices. Endodontic Practice US. 1997;3:13-15.

7. Baratto Filho F, Zaitter S, Haragushiku GA, et al. Analysis of the internal anatomy of maxillary first molars by using different methods, J Endod. 2009;35(3):337-342.

8. Berutti EG, Cantatore A, Castellucci, et al. Use of nickeltitanium rotary PathFile to create the glide path: comparison with manual preflaring in simulated root canals. J Endod.

2009;35(3):408-412.

9. Bellizi R, Hartwell G. Radiographic evaluation of root canal anatomy of in-vivo endodontically treated maxillary premolars. J Endod. 1985;11(1):37-41.

10. Carns EJ, Skidmore AE. Configuration and derivatives of root canals of maxillary first premolars. Oral surg.

1973;36:880-886.

11. de Paula AF, Brito-Júnior M, Quintino AC, et al. Three independent mesial canals in a mandibular molar: four-year follow-up of a case using cone beam computed tomography. Case Rep Dent. 2013;2013.891–849 12. Fava LR. Root canal treatment in an unusual maxillary first molar: A case report. Int Endod J. 2001;4:649-653.

13. Leonardo MR. Aspectos anatomicos da cavidade pulpar: relacoes com o tratamento de canais radiculares. In: Leonardo MR, Leal JM (eds). Endodontia: tratamento de canais radiculares. 3rd ed. Sao Paulo: Panamericana; 1998.

14. Pécora JD, Saquy PC, Sousa Neto MD, Woelfel JB. Root form and canal anatomy of maxillary first premolars. Braz Dent J. 1992;2(2):87-94.

15. Sachdeva GS, Ballal S, Gopikrishna V, Kandaswamy D. Endodontic management of a mandibular second premolar with four roots and four root canals with aid of spiral computed tomography: a case report. J Endod.

2008;34(1):104-107.

16. Sanabria-Liviac D, Moldauer BI, Garcia-Godoy F, et al.

Comparison of the XP-finisher file system and passive ultrasonic irrigation (PUI) on smear layer removal after root canal instrumentation effectiveness of two irrigation methods on smear layer removal. J Dent Oral Health. 2017;4:101.

17. Schäfer E, Bossmann K. Antimicrobial efficacy of chloroxylenol and chlorhexidine in the treatment of infected root canals. Am J Dent. 2001;14(4):233-237.

18. Sert S, Bayirli GS. Evaluation of the root canal configurations of the mandibular and maxillary permanent teeth by gender in the Turkish population. J Endod. 2004;30:391.

19. Song M, Kim HC, Lee W, Kim E. Analysis of the Cause of Failure in Nonsurgical Endodontic Treatment by Microscopic Inspection during Endodontic Microsurgery. J Endod.

2011;37(11):1516-1519.

20. Vertucci FJ.2005; Root canal morphology and its relationship to endodontic procedures, Endodontic Topics.

1979;10(1):3-29.

21. Vertucci FJ, Gegaulf A. Root canal morphology of the maxillary first premolar. J Am Dent Assoc. 1979;99(2):194-198.

22. Yoshioka T, Kobayashi C, Suda H. Detection rate of root canal orifices with a microscope. J Endod. 2002;28:452-453.

Volume 13 Number 1

REF: EP V13.1 RHODES REF: EP V13.1 RIZNYK, ET AL.

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A clinical case of a necrotic UR6 associated with periapical periodontitis

Treatment of maxillary first premolars with three root canals (case report)

RHODES

RIZNYK, ET AL.

1.

2.

3.

4.

5.

(For this patient) Radiographic assessment using a _______ showed a large amalgam restoration distally with poor marginal integrity. a. paralleling periapical radiograph b. CBCT scan c. panoramic image d. bitewing Straight-line access is advisable when using _______ instruments. a. rotary b. reciprocating c. manual d. both a and b Removing calcified material from the coronal aspect ______. a. makes transition deeper into the canal system easier b. reduces stress on instruments c. allows rapid penetration of irrigant into the canal earlier during preparation d. all of the above (For this patient) The orifice of each canal was explored to a depth of a few millimeters with a size 6 and 10 FlexoFile® and then flared with a ProTaper® SX instrument, brushing against the bulkiest wall of the canal and working to a depth approximately _______ the canal length as estimated from the preoperative radiograph. a. half b. one-third c. one-fourth d. three-fourths The risk of blocking the canal during preparation is probably greater when the canal is fine or sclerosed because rotary or reciprocating instruments machine a _______ of the root canal wall and therefore create more dentin chips. a. rougher surface area

Volume 13 Number 1

b. comparatively less surface area c. comparatively greater surface area d. smoother surface area 6.

7.

8.

9.

10.

1.

(When chips and smear block the canal or pack into flutes of the instrument) The volume of available irrigant is also ______ resulting in smear “clumping.” a. increased b. reduced c. thickened d. heated

The _______ of the root canal system is/are the main cause(s) of endodontic failure. a. incomplete instrumentation b. poor irrigation c. poor quality of obturation d. all of the above

2.

_______ can be used to avoid this (blocking the canal) from happening. a. Copious irrigation during preparation b. Recapitulation with a fine file c. A dedicated electric motor d. both a and b

Song, et al. (2011), reported that ______ of possible causes of failure in the previous root canal treatment of upper premolars were missed root canals. a. 11.7% b. 30% c. 50% d. 64%

3.

It is worth mentioning that visualization of threecanalled maxillary premolars on preoperative radiographs can often be difficult. Thus, a careful examination of _______ as an additional diagnostic tool can be useful to detect anatomical variations. a. an intraoral digital photograph b. several preoperative radiographs c. the use of computed tomography d. both b and c

4.

The use of the ______ access cavity modification may be helpful for correct approach to all of the root canals. a. L-shaped b. V-shaped c. T-shaped d. funnel-shaped

Despite superior metallurgy, it is essential to create a reproducible glide path for _______ instruments to follow. a. stainless steel b. titanium aluminum c. nickel-titanium d. copper The glide path reduces the chance of instrument fracture as a result of ______. a. cyclic fatigue b. torsional fatigue c. when the tip becomes locked in the canal d. all of the above Peters, et al., (2002), showed that calcium hydroxide and sterile saline slurry _______ regrowth of endodontic bacteria. a. totally prevents b. has no effect at all on c. limits but does not totally prevent d. encourages

5.

6.

_______ is/are important in endodontics because these facilitate locating canals and approaching them correctly. a. Optical magnification b. Dyes c. Ultrasound tips d. all of the above (For patient in Case report 1) At each change of instrument, the canals were irrigated with 2 ml of

6% ________ solution. a. sodium hypochlorite b. calcium hydroxide c. EDTA d. chlorhexidine 7.

(For the patient in Case report 2) The canals were partially dried with paper points and obturated by ________ obturation technique with gutta percha and premixed bioceramic obturation material TotalFill®. a. warm vertical compaction b. warm lateral compaction c. cold hydrodynamic d. McSpadden compaction

8.

It should be noted that visualization of three canals in a maxillary premolar on preoperative radiographs could often be difficult, because the preoperative radiography gives a ______. a. three-dimensional image of a two-dimensional object b. two-dimensional image of a three-dimensional object c. two-dimensional image of a two-dimensional object d. three-dimensional image of a three-dimensional object

9.

Advanced diagnostic tools such as ______ might give a more accurate picture of root canal morphology. a. 2D digital radiography b. cone-beam computed tomography c. transillumination d. dental loupe

10.

According to the literature, three root canals in the first upper premolar are found in _______ of cases. a. 0.5%-6% b. 1.2%-3.3% c. 2.3%-3.6% d. 5.2%-6.7%

Endodontic practice 39

CE CREDITS

ENDODONTIC PRACTICE CE

PRACTICE MANAGEMENT

Why, when, and how to raise your fees Dr. Albert Goerig discusses the fee schedule equation and your practice’s profitability

D

entistry is a profession that affords us an opportunity to earn a comparatively high income. Most people only dream of the quality of life (particularly the financial benefits) that dental practitioners can achieve during their careers.

There are good reasons for this: the exceptional ability, time, expense, and debt needed to graduate from dental school; the ever-growing costs of acquiring and maintaining a modern practice; ongoing education to maintain professional standards;

Albert Goerig, DDS, MS, is a Diplomate of the American Board of Endodontics and a soughtafter speaker who has lectured extensively in the field of endodontics and practice success throughout the United States, Canada, and abroad. He is the author of over 60 published articles and a contributing author to numerous endodontic textbooks. Dr. Goerig has a private endodontic practice in Olympia, Washington. He has almost 25 years of experience as an educator and practice coach to nearly 1,000 endodontists. Visit www.endomastery.com or email info@ endomastery.com.

40 Endodontic practice

malpractice insurance in today’s tort environment, etc.

We are also business owners and not salary earners. We personally bear all the risks of running a business, including signing leases, employing staff, equipping our premises, marketing, accounting, payroll taxes, and more. Contrary to most working people, as business owners, we are the last to get paid each month. We get what is left over after all other commitments have been met.

For this reason, our practices must be profitable. Our livelihood, our families, and our future depend on profitability from month to month and year to year — and our fee schedule is a vital part of that equation.

Why doctors resist raising fees One of the first questions I ask all my coaching clients is when they last raised their fees. I am always surprised when the answer is 2 or 3 years ago (and sometimes more than that). Certainly, the costs of operating the practice has not stayed the same

during that time, so why haven’t the fees been adjusted to at least keep up with inflation? Generally, the answer is one or more of the following reasons: Uncertainty Many doctors neglect to update their fees because they are uncertain how frequently they should and/or how to do it.

Patient attitudes Patients tell us every day how expensive our fees are, and we know that for the average family, dentistry can be a significant expense. Sometimes patients make jokes about paying for our expensive car, or they outright accuse us of being overpaid or greedy. These can be difficult, embarrassing conversations that cause us to doubt our value.

Fear of nonacceptance Related to the affordability of care, we also worry that higher fees may result in more Volume 13 Number 1

Lack of control Finally, insurance providers set their own reimbursement rates and limit what we can charge. As a result, we may feel our own fee schedule does really matter since the insurance company will pay what it pays. This feeling is more prevalent in practices that have a very high ratio of insurance patients.

Why you need to raise fees The most important reason to raise your fees is self-respect for your professional value and to maintain the viability of your practice at healthy levels. It’s just good business sense to set your fees regularly in context with the marketplace, and dentistry as a profession is stronger when doctors are managing their practices smartly. It ensures patients continue to have access to the highest quality of care.

Patients are always going to say fees are high, but realize they are not talking about your fees specifically. They just mean the cost of dentistry in general, so don’t take it personally. Plus, when you present treatment to the patient, you don’t say, “Last year, this procedure cost $x, but I recently increased my fees, so now it costs $y.” Trust me, when you raise your fees, patients don’t even notice because they don’t know what your fees are now.

I also strongly believe that doctors need to continue to set their fees independently regardless of insurance company rates. First, because not all your patients have insurance, and you need to have an up-to-date standard office fee schedule. Second, despite the opaqueness of how insurance companies determine their UCR rates, it’s important to have your office fee set appropriately for

claims submission when data is collected about your fees.

Finally, and if for no other reason, your fees need to be kept updated, so you are continually aware of how much you are discounting your fees to the insurance plans you participate in. If it has been a while since you set your fees properly, the growing gap on some plans might be startling.

How raising fees boosts profits Even more startling might be how much profitability you are giving up by not raising your fees regularly. In fact, raising fees is the fastest way to grow the bottom line of the practice when appropriate.

If you’re lagging behind, and you implement a fee increase, you will notice a difference in revenues and profitability immediately without changing anything else in the practice. You can estimate how much of an impact a fee change might have on your profitability with the following formula: Goal Fee Increase (%) ÷ Profitability Ratio (%) x Full Fee Revenue Share (%) = Increase in Profitability (%) For example, consider a practice with 55% overheads (45% profitability), and 60% of revenues are full-fee procedures (the rest are inelastic insurance fee procedures). A 10% fee increase would result in: 10% Fee Increase ÷ 45% Profitability Ratio x 60% Full Fee Revenue Share = 13.3% Increase in Profitability If that practice had $1,000,000 in revenues to begin with, then the bottom line grows by $60,000 from $450k to $510k overnight. You can halve that amount of growth for a 5% fee increase, or double it for a 20% fee increase.

When and how to raise your fees It might be exciting to get that kind of overnight boost in profitability going forward,

but don’t forget that fees in the past may have been suppressed by not appropriately raising fees on a timely basis.

To avoid these lost opportunity costs, it is essential that you raise your fees on an annual basis at a minimum. However, I recommend doing this process twice a year because your costs are always increasing due to ongoing inflation.

By setting fees regularly in this way, your profitability is always being optimized to current fee levels. You can think of this process more like a “calibration” to the current business, dental, and patient landscape, rather than just raising fees for its own sake.

To help you set your fees properly, there are plenty of resources available to you.

Check out the ADA fee survey at the ADA. org store (free for ADA members). Probably the most valuable resource is going to be a fee reporting and analysis service such as the NDAS dental fee guide at https://wassermanmedical.com. These paid services give you a competitive fee report showing the ranges of fees charged by CDT procedure code and localized to your area and zip code.

Now, so far in this article, we have talked about the need to raise fees based on time passing. However, there is another very important factor to consider. When you look at a competitive fee report, you see a range, usually broken into percentiles. It’s important to consider that range carefully and where your current fees sit.

These fee guides are the fees of general dentists, but as an endodontist, you should be around the 90th to 95th percentile on comparable fees. I can’t tell you what percentile or fee level is right for your practice, but, ultimately, what you choose also reflects your self-worth and self-belief in your value — as a doctor providing highquality patient care and as a member of the dental profession. EP

Free Download: 2020 Endo Mastery Fee Increase Calculator Estimate how profits can grow by raising fees in your practice!

Endo Mastery’s fee increase calculator is a free Excel spreadsheet preloaded with typical endodontic procedure codes based on the updated CDT list for 2020. Enter your current fees, the number of procedures you perform, and how much to raise your fees, and the calculator will estimate the improvement to your bottom line.

Free Download: https://www.endomastery.com/feecalculator

Volume 13 Number 1

Endodontic practice 41

PRACTICE MANAGEMENT

patients not accepting treatment, which can impact our productivity. Specialists also worry about patients telling referring doctors that the specialist is too expensive, which might affect the referral relationship.

PRODUCT PROFILE

ENDOSEAL MTA Dr. Jeffrey D. Krupp discusses the excellent physical and biological properties of this obturation material

R

oot canal fillings aim to seal the root canal system to prevent reinfection of the periapex. Obturation should eliminate all routes of leakage from the oral cavity and the periradicular tissues into the root canal system by creating a fluid-tight seal. Therefore, root canal filling materials and endodontic sealers should seal the canal laterally and apically and have good adaptation to the root canal dentin.1,2 The arrival of bioceramic endodontic sealers to the clinical endodontics playing field is highly therapeutic. The introduction and increased use of these advanced materials facilitates the main objectives of endodontic obturation. Their chemical formulation and biological properties have shifted the field from using biologically inactive materials to utilizing biologically active materials. We have therefore progressed from a physical endodontic seal of inactive materials to a biological endodontic seal of active materials by way of biomineralization of dentin with bioceramic sealers.

The first bioceramic material successfully used in endodontics was the mineral trioxide aggregate (MTA) cement, which was introduced by Dr. Mahmoud Torabinejad in 1993. It is osseoconductive, inductive, and biocompatible.3 ENDOSEAL MTA (Maruchi; Wonju, Korea) is a paste-type root canal sealer based on pozzolan cement that has the same excellent physical and biological properties of traditional MTA. ENDOSEAL MTA is a radiopaque, nonresorbable paste for the permanent obturation of the root canal system. Its composition is well tolerated by the tissues and provides anti-inflammatory, antiseptic, and germicidal actions.4 The sealer is produced in a syringe, unlike many existing products composed of powder and liquid. This means it can be directly injected into the canal system without a rigorous mixing process. In addition,

Jeffrey D. Krupp, DDS, MS, is a graduate of the UCLA School of Dentistry. He received his postgraduate degree along with his Master of Science degree in Endodontics from Marquette University. He has been at the same location serving the greater San Jose area in Endodontics for over 30 years.

42 Endodontic practice

calcium hydroxide produced is released during the setting process to induce hard tissue formation, which has been shown to have a strong antimicrobial effect against E. faecalis. Another beneficial characteristic is that the sealer expands 2% upon setting, rather than shrinking like traditional endodontic sealers. This allows for a better three-dimensional fill.

After using the ENDOSEAL MTA for a few years, I have personally noticed that the high biocompatibility of this product has minimized patient post-op discomfort. The material is easy to handle as it does not require an arduous mixing process and can be directly injected into the canal. During obturation, the flow of the material appears seamless, not trapping air while flowing in three dimensions.

ENDOSEAL MTA, one of the latest and most extensively tested obturation materials, excels with high biocompatibility, excellent antimicrobial properties, exceptional flow, expansion during setting, high radiopacity, low solubility in contact with tissue fluids, and a substantially shortened setting time (in mere minutes).5-8 The rapid-setting ability of ENDOSEAL MTA creates a completely new repertoire of clinical applications and improves appointment efficiency compared to past MTA and bioceramic sealers that required hours or days to set. In past generations of MTA/bioceramic sealers, clinical applications beyond obturation were limited due to the risk of the material washout in procedures such as pulp capping, perforation repair, and root-end surgery. These procedures would require a more substantive and more difficult-to-use MTA/bioceramic material, necessitating

additional appointments to confirm full set of the material. On the other hand, ENDOSEAL MTA’s patented formulation uses pozzolan reactions to quicken setting times without adding chemical catalysts that disrupt biocompatibility and bioactivity. Its novel pozzolan cement-based formulation also promotes intratubular biomineralization.9,10 For all of the above reasons and its easeof-use in my hands, I have become an avid user of the ENDOSEAL MTA sealer. As the field of endodontics evolves with novel and improved technologies and materials, we can truly benefit from evolving along with it. EP This information was provided by Maruchi.

REFERENCES 1. Özcan E, Eldeniz AU, Arı H. Bacterial killing by several root filling materials and methods in an ex vivo infected root canal model. Int Endod J. 2011;44(12):1102-1109.

2. Singh Chandra, Rao S, Chandrashekar, V An in vitro comparison of penetration depth of two root canal sealers: An SEM study. J Conserv Dent. 2012;15(3):261–264.

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

4. Endoseal [product details]. https://www.indiamart.com/ proddetail/endoseal-root-canal-obturationcement-21208201662.html. Accessed January 30, 2020.

5. Kaur A, Shah N, Logani A, Mishra N. Biotoxicity of commonly used root canal sealers: a meta-analysis. J Conserv Dent.

2015;18(2):83-88.

6. Ørstavik D. Materials used for root canal obturation: technical, biological and clinical testing. Endodontics Topics.

2005;12(1):25-38.

7. Al-Haddad A, Che Ab Aziz ZA. Bioceramic-Based Root Canal Sealers: A Review. Int J Biomaterials. 2016.

8. Lee BN, Hwang YC, Jang JH, et al. Improvement of the properties of mineral trioxide aggregate by mixing with hydration accelerators. J Endod. 2011;37(10):1433-1438.

9. Lee JK, Kwak SW, Ha JH, Lee W, Kim HC. Physicochemical Properties of Epoxy Resin-Based and Bioceramic-Based Root Canal Sealers. Bioinorg Chem Appl. 2017.

10. Yoo YJ, Baek SH, Kum KY, et al. Dynamic intratubular biomineralization following root canal obturation with pozzolan-based mineral trioxide aggregate sealer cement.

Scanning. 2016; 38(1):50-56.

Volume 13 Number 1

ENDOSEAL Mineral Trioxide Aggregate

MTA

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Injecting ENDOSEAL MTA into the middle third of root canal and slowly pumping it to the root apex with GP cone can achieve sufficient root canal filling.

• Bioceramic injectable sealer • 3g syringe with 20 tips • Fast setting time

In a single cone technique, GP cone act as a guide and ENDOSEAL MTA act as a filler.

• Strong antibacterial effects • Superior dimensional stability • Easy retrieval with NiTi files • Hermetic apical sealing • High radiopacity

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100

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Symmetric R-phase NiTi Thermal activation Apical drainage Micro-streaming

Most effective ultrasonic activator system

For more information, visit MaruchiUSA.com For dealership inquiries or to place an order, contact sales@maruchiusa.com or 714.988.6632

PRODUCT SPOTLIGHT

Boyd Industries — products specifically for the endodontic market

“B

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

As an industry expert in the design of specialty equipment, Boyd has developed a line of products specifically for the endodontic market.

Featured Product: S3100LC Endodontic Chair

Boyd Industries is proud to promote our new dental treatment chair designed for endodontic procedures. This chair combines reliable functionality with elegant design and includes ergonomic features to accommodate doctor, assistant, and patient needs.

What makes the S3100LC design unique?

• Lockable swivel base capable of 90 degrees of rotation from center (180 degree total rotation) to ensure greatest ease of patient positioning and entry/egress.

• Lift column base allows chair to be raised or lowered with precision in a fixed field of view.

• Tapered back design facilitates closer assistant positioning while maintaining patient comfort. Low profile, double articulating headrest for proper positioning of patient head.

• Easy-to-access membrane switches on left and right side of chair back control both base and back adjustments. Three programmable settings for one-touch control to articulate chair to frequently used positions with a “Home” button to return chair to lowered and upright position for patient egress.

44 Endodontic practice

S3100LC Endodontic Treatment Chair

• Ultraleather Pro™ fabric upholstery and memory foam come standard to support maximum patient comfort.

Ultraleather Pro™ is ink and stainresistant, with antimicrobial disinfecting ingredients.

Standard Features • Integrated smooth swivel with easyaccess release lever • Programmable hand controls integrated on both sides of the chair back • Detachable and programmable foot control • Low-voltage DC actuator vertical lift column base (rated for patients up to 500 lbs.)

• Tapered back with sculpted headrest location to allow proper positioning • Lever-release drop down arms • Ultraleather Pro™ and memory-foam upholstery • Fixed toe section with clear plastic foot-protector cover • Pinch-lock, double-articulating headrest

Featured Product: BOS310 Endodontic Stool The BOS310 Endodontic Stool offers the widest range of adjustments to perfectly fit, support, and protect endodontic specialists’ arms, hands, and backs against longterm strain. The BOS310 adapts ergonomic

BOS310 Endodontic Stool Volume 13 Number 1

Endodontic stool arms may be rotated individually into seven different positions Volume 13 Number 1

PRODUCT SPOTLIGHT

design concepts from Boyd’s award-winning doctor- and assistant-seating product line with a patent-pending forearm support system. Built to Boyd’s highly recognized quality standards, this seat will provide many years of service.

What makes the BOS310 design unique?

• Hands-free armrest rotation reduces the necessity of glove disposal and replacement during standard procedures.

• Patent-pending arms may be rotated individually into seven different positions, up to 90-degree rotation, to offer maximum ergonomic arm and hand positioning.

• Arm-locking feature to ensure stability at each position.

• Adjustable arm height and width to ensure correct posture.

• New curved-back bracket design adjusts to your most comfortable seated position for increased lumbar support and reduced strain.

Standard features • Five (5) caster aluminum base, with neoprene-coated dual-wheel casters for smooth movement • Wide, ergonomic seat for added stability and comfort • Pneumatic cylinder height adjustment • Seat tilt to allow adjustment for proper pelvic/spine alignment • Padded backrest for your comfort • Choice of upholstery from the full range of Boyd-approved suppliers to seamlessly match your office design

Prestige Endodontic Cart

Featured Product: Prestige Endodontic Cart The Prestige Endodontic Cart has been fitted with a lightweight aluminum body and all the features you need: aseptic surfaces for easy cleaning, sectioned drawers for intuitive organization, and a sleek, contemporary esthetic.

Standard Features • A removable plastic top designed for easy cleaning, in addition to dual slide-out surfaces for added work space.

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

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

• Auto-closing, ball-bearing drawers.

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

Dimensions: 29" x 25" x 42" The Boyd team has made every effort to create specialized products that are truly “Built for You.” These featured products can be combined with Boyd’s custom clinical and office cabinetry to create a fully cohesive office space. Personalize your practice

with nearly limitless combinations of color and print laminates and the widest range of upholstery choices on the market. Reach out to your regional sales representative today to get started!

To learn more, visit us at www.boyd industries.com or stop by our booth during the American Association of Endodontists (AAE) Annual Meeting in 2020! You can also follow us on Instagram and Twitter @BoydIndustries.

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

Endodontic practice 45

SERVICE PROFILE

Large Practice Sales Chip Fichtner explains how it pays to know your practice value to a silent partner

U

nderstanding your practice value in today’s bubble is important for several reasons, including estate and insurance planning. It is even more critical when negotiating potential associate buy-ins. It may also surprise you how the value of your practice today may entice you to monetize part of it for cash now from a “silent partner” to secure your financial future at today’s low tax rates. You continue to run your practice under your brand as a partial owner benefitting from your new partner’s resources.

For decades, Dental Support Organizations (DSO) have been eagerly acquiring dental practices. Thousands of general dental practices have become affiliated with DSOs. Estimates range from 15% to 20% of all U.S. dentists are now affiliated with a DSO with a 15% annual growth rate.

A decade ago pediatric dentists were the targets of specialty DSOs. About 6 years ago orthodontics became the most popular specialty. In the past 2 years, OMFS practices have achieved stunning values, and finally in 2019, the money tree sprouted for endodontists.

This is not to imply that DSOs did not acquire endodontists prior to 2019, but there are now dozens of groups interested in acquiring endodontic practices, which is driving values higher for now. The old value of your practice was typically 60% to 90% of collections. Today the values of large practices can exceed 200% of collections from certain buyers and even more if your advisor can create a bidding contest with multiple suitors.

The groups paying the highest values for endodontic practices are the Invisible DSOs (IDSOs). These groups quietly own interests in dozens or hundreds of practices

Chip Fichtner is the founder of Large Practice Sales, which specializes in invisible DSO transactions for large practices of all specialties.

The company has completed more than $100 million in transactions in the last six months.

Learn more at largepracticesales.com.

46 Endodontic practice

Today the values of large practices can exceed 200% of collections from certain buyers and even more if your advisor can create a bidding contest with multiple suitors.

across the country in which they become silent partners with doctors of all specialties.

The IDSOs’ goal is to invest in great doctors who have larger practices and a growth plan.

They are eager for doctors who will remain as owners, running the practice under the doctors’ brand, team, and strategy for 5, 10, or 20-plus years.

The IDSO strategy is to choose endodontists who can benefit from the resources of a larger partner. IDSOs quietly purchase between 60% and 90% of a practice for cash up front with the doctor retaining ownership in the practice, the parent, or a combination of both. IDSOs look for practices in which their resources of purchasing power, payor negotiation leverage, and synergies with other practices within their group can accelerate the growth of their new endodontist partners.

IDSOs can also ease the burdens of practice administration. While they do not run or micromanage the practice, they can be very helpful in areas where size and scale can add value and enable the doctor to focus on patient care rather than administrative minutiae.

While an IDSO partner will ultimately acquire the balance of the practice when the doctor is ready to retire, these transactions are attractive to doctors even younger than 40. Doctors can utilize the IDSO partner’s resources and capital to grow through new office buildouts, acquisitions, and external

marketing with no risk to the doctor. With the right partner, a doctor can grow the value of the doctor’s retained ownership over many years to be worth multiples of the 100% they owned today. This long-term wealth creation can be at the practice level and/or through ownership in the parent.

Billions of dollars have been harvested in the DSO industry, and many doctors have been participants.

An IDSO partnership is very much like a marriage rather than a one-time transaction.

The doctor and the IDSO partner will in most cases be working together for many years.

Choosing the right partner and a structure that meets the doctors’ goals is critical to a great, long-term marriage. It pays to “date” multiple suitors, not only to increase value, but also to find the perfect fit.

Many of these IDSOs will contact you directly in the coming quarters. Their goal will be to urge you to complete a transaction directly with them without the assistance of a professional advisor. This is a trap. The right advisor will introduce you to multiple potential partners, thus driving up the value to you and allowing you to select the partner that meets your objectives both short and long term.

To confidentially learn the value of your practice in today’s bubble, Large Practice Sales is happy to help you at no cost or obligation. In the worst case, you will learn something. EP Volume 13 Number 1

Recent Transactions Silent Partners Invest In All Practice Specialties (Invisible DSOs)

Recent Transactions

2X Collections, Two-Doctor General Practice, Age 30s, Sold 60%, Retained 40% 3.9X Collections, Four-Doctor Oral Surgery, Three Offices, Stunning Value 2.6X Collections, One-Doctor Periodontist and new partner will start a new office in six months. $17,000,000, One-Doctor Orthodontist achieved 3.4X collections in a no-growth area.

Every Transaction Customized

Gain Capital For Growth • Known Exit When Ready • Remain Practice Owner • Your Team, Your Brand Visit FindMyEndoPartner.com to register for the next webinar.

Call 877-557-5119 or email EndoUs@LargePracticeSales.com to arrange a confidential discussion with an LPS principal.

You might be surprised...

SMALL TALK

The critical element is missing from most leadership assessments Drs. Joel Small and Edwin (Mac) McDonald discuss an assessment that highly correlates with leadership effectiveness

T

here is no question that we practice in a feedback-rich environment.

Unlike CEOs of large corporations who often find themselves living in a bubble and isolated from useful feedback because of the enormity of their organizations, as healthcare clinicians, we benefit from the smaller size of our practices.

Feedback is readily available to us.

Because we have no hierarchical structure through which feedback is filtered and diluted before it reaches us, we can benefit from this wonderful source of information.

Hogan and Hogan’s study,1 reported in the International Journal of Selection and Assessment, claims that one of the best and most reliable indicators of leadership effectiveness is feedback received from direct reports (i.e., our staff).

Yet we find that too often we turn our backs or disregard this vital and readily available information.

How can we possibly know that we are being effective leaders unless we ask those we lead?

Every executive coach knows to ask clients for feedback, so we can become the best possible coach for that client. The same should be true for leaders; however, we too often make useless and incorrect personal assumptions regarding our leadership effectiveness. Perhaps we feel that asking for this kind of feedback from our staff would be considered a sign of vulnerability in the form of insecurity or uncertainty. Our 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.

48 Endodontic practice

experience is that the exact opposite is true.

By asking those we lead for honest, unfiltered feedback, we are demonstrating that we are listening and authentically desire to improve for the benefit of all.

Not everyone responds to a “cookie cutter” approach to coaching or leadership.

Leadership must be nuanced to fit the needs of the followers, and leaders must be able to tweak their style to address the dynamics of an ever-changing and complex practice environment.

This is not to say that leaders must be chameleons and change their identity to meet the needs of others. In fact, our authenticity plays a vital role in our ability to lead. What we are proposing here is that leaders become agile enough to try different authentic approaches to leading others.

Every doctor will greatly benefit from unfiltered feedback; however, some doctors may have difficulty receiving honest and unfiltered feedback if they have not created a psychologically safe culture in which staff members can speak openly without fear of reprisal.

So, how do doctors know if they are leading effectively, or what needs to change if their leadership is lacking?

Line of Sight Coaching, LLC utilizes what we believe to be the best possible leadership assessment available today.

The Leadership Circle Profile 360 is a scientifically based assessment that has been shown to highly correlate with leadership effectiveness. It is highly regarded by corporate executive coaches and has application in the healthcare industry. It has been particularly effective in small organizations such as clinical healthcare practices.

The Leadership Circle 360 Profile assessment not only has the doctor conduct a leadership self-assessment, but also has the staff and other practice stakeholders complete their own assessment of the leader’s capabilities. The resulting data gives doctors a bird’s-eye view of their leadership, as seen through the eyes of those they lead. The results offer both quantitative data and

qualitative information derived from the assessment survey and written testimony by the evaluators. Most importantly, the evaluator’s responses are anonymous, so there is no fear of providing honest feedback.

For those truly interested in becoming the best leaders possible for their practice, the information that a Leadership Circle 360 Profile can provide is invaluable.

Coaches will often zero in on those areas that indicate significant differences between the doctor’s self-evaluation and the staff’s anonymous evaluation.

These areas of discrepancy are often caused by blind spots or self-limiting beliefs that are unknown to the doctor, yet they significantly diminish our ability to lead effectively. Once these limiting factors are uncovered, the doctor, in conjunction with the coach, can develop a leadership development plan that addresses these areas and design corrective behaviors that are nuanced to fit the doctor’s specific leadership style.

The benefits of becoming a better leader are significant.

Numerous studies have shown that wellled practices are: • More productive and profitable.

• Developing brands that are a reflection of a strong, engaging culture.

• Attracting and maintaining the very best staff.

• Creating strong cultures that endure and serve as a sustainable competitive advantage in the healthcare marketplace.

If you are interested in having a better practice, one that brings you joy, fulfillment, and the lifestyle you desire, consider investing in your development as a leader.

Seeing yourself as a leader through the eyes of those you lead is a unique experience, and forms the basis for increased self-awareness and growth. EP REFERENCE 1. Hogan R, Hogan J. Assessing Leadership: A View from the Dark Side. International Journal of Selection and Assessment. 2001;9(1-2):40-51.

Volume 13 Number 1

Experiencing the power of digital communication.

ZEISS EXTARO 300 g Sprin l ia spec ff o 50%

Receive 50% off a complete communication package with the purchase of an EXTARO 300 premium package. 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.

Tour the advanced technology of ZEISS EXTARO 300 at the American Association of Endodontists Annual Conference. April 1 - 4, 2020 | ZEISS Booth 301 Offer valid March 15 – June 30, 2020 or while supplies last, exclusively for Carl Zeiss Meditec, Inc. equipment as specified above and for U.S. customers only. Cannot be combined with any other offer.

SUR.11393 Rev E ©2020 Carl Zeiss Meditec, Inc. All rights reserved.

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