Đang tải... (xem toàn văn)
Tạp chí nội nha OPUS tháng 01+02/2014 Vol.7 No.1
a revolutionary company that aims to redene and transform traditional root canal therapy So·nen·do: Visit: Page 6 Clinical management of teeth with incomplete root formation Dr. Siju Jacob PAYING SUBSCRIBERS EARN 24 CONTINUING EDUCATION CREDITS PER YEAR! A conservative approach for internal bleaching of a vital anterior tooth with calcified pulp chamber Drs. David Keinan and Eugene A. Pantera Jr. clinical articles • management advice • practice proles • technology reviews January/February 2014 – Vol 7 No 1 PROMOTING EXCELLENCE IN ENDODONTICS Corporate insight Sonendo ® The importance of a reproducible glide path Drs. Yosef Nahmias, Imran Cassim, and Gary Glassman Feedback – lateral thinking Jacqui Goss BUC ® Ultrasonics Obturation Ultrasonics Surgery Use for Access Refinement, Retreatment, and Restorative procedures. There’s a BUC tip ready to accomplish a multitude of endodontic treatment challenges. Call (800) 344-1321 today to receive 20% off your next ultrasonic tip order! © 2014 Obtura Spartan Endodontics. See instructions for use. Rx Only. Products may not be available in all areas. Please contact your Obtura Spartan Endodontics Sales Representative for availability and pricing. Obtura Spartan Endodontics – 2260 Wendt Street, Algonquin, IL 60102. INTRODUCTION Volume 7 Number 1 Endodontic practice 1 January/February 2014 - Volume 7 Number 1 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-in-chief 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 PUBLISHER | Lisa Moler Email: lmoler@medmarkaz.com Tel: (480) 403-1505 MANAGING EDITOR | Mali Schantz-Feld Email: mali@medmarkaz.com Tel: (727) 515-5118 ASSISTANT EDITOR | Elizabeth Romanek Email: betty@medmarkaz.com Tel: (727) 560-0255 EDITORIAL ASSISTANT | Mandi Gross Email: mandi@medmarkaz.com Tel: (727) 393-3394 DIRECTOR OF SALES | Michelle Manning Email: michelle@medmarkaz.com Tel: (480) 621-8955 NATIONAL SALES/MARKETING MANAGER Drew Thornley Email: drew@medmarkaz.com Tel: (619) 459-9595 PRODUCTION MANAGER/CLIENT RELATIONS Adrienne Good Email: agood@medmarkaz.com Tel: (623) 340-4373 PRODUCTION ASST./SUBSCRIPTION COORD. Jacqueline Baker Email: JBaker@medmarkaz.com Tel: (480) 621-8955 MedMark, LLC 15720 N. Greenway-Hayden Loop #9 Scottsdale, AZ 85260 Tel: (480) 621-8955 Fax: (480) 629-4002 Toll-free: (866) 579-9496 Web: www.endopracticeus.com SUBSCRIPTION RATES 1 year (6 issues) $99 3 years (18 issues) $239 © FMC, Ltd 2014. All rights reserved. FMC is part of the specialist publishing group Springer Science+Business Media. 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 or the publisher. T he beginning of the New Year usually brings an examination of what we’ve learned from the past and a prediction of what lies ahead, and such examinations are critical to maintaining a standard of excellence in our discipline. With regard to our endodontic practices, it’s clear that the increasing pace of innovation is revolutionizing the way we practice, as it will change every form of healthcare practice. The areas of most rapid innovation within endodontics will include cone-beam computed tomography with new algorithms to improve assessments and facilitate surgical guidance, enhanced disinfection and shaping techniques, nanotechnology, innovative advances in obturation that promise safer treatment, improved workflow, and better outcomes and regenerative procedures. Stringent laboratory and clinical evaluations will be validating these innovations at an increasing pace, and more sophisticated studies will present clinicians with rigorously examined innovation opportunities that will provide very significant improvements to the practice of endodontics. As in most forms of medicine, it is not only the rate of change but the degree of difference that is increasing. The adoption of such innovations is becoming ever more compelling. Conversely, ignoring innovation is becoming an ever- increasing professional risk. Over the past 50 years, change management has evolved as a recognized discipline. It was once a viable belief that specialists could achieve success by using the same treatments and business strategies for the greater part of their clinical career. For the current community of endodontists, such a notion is seriously flawed. Today, there are new products, technological developments, increased competition, and a changing workforce that require us to change course in order provide the most successful outcomes for our patients and to stay competitive. Most successful companies undergo moderate organizational change yearly and major changes every 4 to 5 years. 1 But in spite of all this management attention, most studies show only moderate success for organizational change. This would suggest that Kotter’s classic eight success factors 2 is also flawed. What is going on here? Perhaps two additional factors need to be considered, both of which may contradict other notions that served us in the past: • Change should not be episodic. Rather than considering change as a planned and defined part of our business plan, we should integrate change into the way we execute our business plan. This means that new approaches to treatment and business operations need to be examined on a continual basis and that we, as leaders of our practices, should adopt behavioral patterns that transform rather than maintain. This requires changing the fundamental values and principles of our organization and the individuals within it. Each member is continuously seeking better ways to operate as part of a team to improve results. But consider such a concept carefully, because this level of transformation does not require management. It requires leadership. • Change should not be hierarchical. Change from the top can never be adequate to the challenges of making the myriad of changes required to improve a complex organization. Rather than deciding and dictating change, the best practice leaders will inspire and coach change — structuring their organizations to actually breed ideas for improvement. In a recent case study, Kotter talks about the need to accelerate change by using a dual organizational structure. The problem is that most businesses have a hierarchical structure that maintains processes very well, but resists change. How many of our practices operate this way? Kotter proposes a parallel structure where employees at all levels are invited to contribute to change in a different, but complementary, way. He stated that creating a sense of urgency around a single opportunity (or problem) is a good way to start 3 and to get people accustomed to contributing ideas independently of management roles and structure. Any size practice can benefit from such a parallel concept: Daily management of patient flow and procedures can be managed by a hierarchy of priorities and team member roles, but ideas for improvement should flow in parallel, unimpeded by hierarchy. So as the New Year begins, we must consider a qualitative review of our perspectives on treatment and the organizational culture of our practices. Most successful change efforts require creating a change-capable organization that is always ready to examine and adapt to new treatment protocols and office operational demands, all supported by the evidence and metrics, respectively. This means establishing a sense of urgency and creating a strategy that is supple and ready for modification as conditions change. At the Harvard Medical School 2013 Class Day address, Dr. Bruce Donoff, dean of the Harvard School of Dental Medicine, said, “We educated you in a way that does not simply repeat the lectures of the past but prepares you to understand and see new knowledge in the continuously changing field as well as in the wider world.” 4 I would encourage us all to improve our individual, staff, and practice abilities to benefit from the ongoing stream of innovation that will enable us to continuously improve patient care. It is an exciting age in which to be practicing dental medicine. Best wishes for this New Year and years ahead. Martin D. Levin, DMD Diplomate, American Board of Endodontics Clinical Associate Professor of Endodontics, University of Pennsylvania www.endonet.com and www.endocc.com Dental medicine in an age of change 1. Allen, SA. Organizational choices and general management influence networks in divisionalized companies. Academy of Management Journal. 1978;21(3):341- 365. 2. Kotter, JP. Leading change. Boston: Harvard Business Review Press; 1996. 3. Kotter, JP. Accelerate! Harvard Business Review. 2012;90(11): 44-58. 4. Harvard Medical School. Change in Medicine theme for new HMS grads. Harvard Medical School News, May 30, 2013. Http://hms.harvard.edu/news/change- medicine-theme-new-hms-grads-5-30-13. Accessed January 1, 2014. TABLE OF CONTENTS Clinical Clinical guidelines for the use of ProTaper Next ™ instruments: part one Drs. Peet J. van der Vyver and Michael J. Scianamblo discuss the clinical guidelines for using ProTaper Next ™ instruments 12 BT-Race — Biologic and conservative root canal instrumentation with the final restoration in mind Drs. Gilberto Debelian and Martin Trope explore the BT-Race system 22 A conservative approach for internal bleaching of a vital anterior tooth with calcified pulp chamber Drs. David Keinan and Eugene A. Pantera Jr. solve a common endodontic problem in a conservative way 25 2 Endodontic practice Volume 7 Number 1 Clinical 7 Accuracy of a new apex locator in ex-vivo teeth using scanning electron microscopy Drs. Maria Bonilla, Taner Cem Sayin, Brenda Schobert, and Patrick Hardigan compare the accuracy of root canal working lengths in 200 ex-vivo teeth determined using a fourth-generation electronic apex locator and a new fifth- generation electronic apex locator ON THE COVER Cover photo courtesy of Drs. Peet J. van der Vyver and Michael J. Scianamblo. Article begins on page 12. Corporate insight 6 Sonendo ® — A new paradigm in endodontics At the 2014 AAE Annual Session, Sonendo is debuting its Multisonic Ultracleaning System that uses a mixture of irrigating fluids and sound waves to clean inside the roots of teeth. simple, adaptable endodontic solutions Perfect delivery. Optimal performance. Easy removal. UltraCal ® XS 800.552.5512 ultradent.com Scan to watch a short video of UltraCal XS. Don’t change your technique. Make it easier with UltraCal ® XS and Citric Acid 20%. NaviTip tip delivers UltraCal XS where it is needed in the canal. ©2013 Ultradent Products, Inc. All Rights Reserved. UltraCal ® XS and Citric Acid 20% UltraCal XS, a uniquely formulated calcium hydroxide paste (pH 12.5), can be easily delivered with the NaviTip ® tip exactly where it is needed in the canal. Calcium hydroxide offers strong antimicrobial effects and potentially stimulates the healing of bone to promote healing in infected canals. 1 For two-appointment RCTs, no other medicament works better than UltraCal XS. When it comes time to remove UltraCal XS from the canal, look no further than Ultradent’s Citric Acid 20%, delivered with the NaviTip FX tip. Citric Acid 20% easily dissolves calcium hydroxide, and the small bers attached to the NaviTip FX tip easily scrub the walls of the canal, which also helps remove the smear layer. So you know the canal is ready for obturation. 1. Gomes BP, Ferraz CC, Vianna ME, Rosalen PL, Zaia AA, Teixeira FB, et al. In vitro antimicrobial activity of calcium hydroxide pastes and their vehicles against selected microorganisms. Braz Dent J. 200 2;13(3):155- 61. Use NaviTip ® tip to place UltraCal ® XS in the canal, and use Citric Acid with the NaviTip ® FX ® tip to easily remove it. NaviTip tip NaviTip FX tip with brush bers TABLE OF CONTENTS Continuing education The importance of a reproducible glide path Drs. Yosef Nahmias, Imran Cassim, and Gary Glassman discuss how rotary and reciprocating instruments that follow a designated route will result in more successful outcomes and minimal iatrogenic mishaps 28 Clinical management of teeth with incomplete root formation Dr. Siju Jacob discusses treatment techniques for teeth with incomplete root formation 34 Abstracts The latest in endodontic research Dr. Kishor Gulabivala presents the latest literature, keeping you up-to- date with the most relevant research 41 Anatomy matters Endodontic accountability: The “X” factor, part 9 Dr. John West discusses knowledge, skill, and willingness in endodontics 43 Endospective The cookbook’s not working — what’s next? Dr. Rich Mounce discusses a superior method for cleaning canals 48 Product insight What is the ideal endodontic interappointment medicament, its most effective placement and removal technique? Drs. Carlos A.S. Ramos, Richard D. Tuttle, and Mr. Daniel C. White explain the benefits of UltraCal ® XS 50 Practice management Feedback – lateral thinking Jacqui Goss explains how to gather reliable patient feedback 52 Materials & equipment 54 Diary 56 4 Endodontic practice Volume 7 Number 1 Clinical management of teeth 34 ORTHOPHOS XG 3D ORTHOPHOS XG 3D The right solution for your diagnostic needs. Implantologists will appreciate the seamless clinical workflow from initial diagnostics, to treatment planning, to ordering surgical guides and final implant placement. Endodontists will enjoy instantly viewable 3D volumetric images for revealing and measuring canal shapes, depths and anatomies. Orthodontists will benefit from high- quality pan and ceph images for optimized therapy planning. General Practitioners will achieve greater diagnostic accuracy for routine cases. “With my Sirona 3D unit, I can see the anatomy of canals, calcification, extent of resorption, frac- tures, and sizes of periapical radiolucencies, all of which influence treatment plans for my patients. Combine that with the metal artifact reduction software that reduces distortions from metal objects, my treatment process is a lot less stressful. My patients benefit from the technology and my referrals appreciate the value.” ~ Dr. Kathryn Stuart, Endodontist - Fishers, Indiana For more information, visit www.Sirona3D.com or call Sirona at: 800.659.5977 The advantages of 2D & 3D in one comprehensive unit ORTHOPHOS XG 3D is a hybrid system that provides clinical workflow advantages, along with the lowest possible effective dose for the patient. Its 3D function provides diagnostic accuracy when you need it most: for implants, surgical procedures and volumetric imaging of the jaws, sinuses and other dental anatomy. www.facebook.com/Sirona3D 6 Endodontic practice Volume 7 Number 1 CORPORATE INSIGHT A new paradigm in endodontics “Our goal is to transform endodontics by improving the clinical quality and business performance of practices performing root canal therapy,” said Bjarne Bergheim, President and Chief Executive Officer of Sonendo. Company History The mission of Sonendo ® is to lead the transformation of endodontics through Sound Science ® . At its core, Sound Science means that we are committed to ensuring that our product development is based on sound scientific research, and extensive proof source. Furthermore, we will continue to leverage our innovative approach to sound — and its use in endodontics — as we work to bring this disruptive new technology to the endodontic community. Sonendo is a privately held company located in Laguna Hills, California, and employs over 50 people. Sonendo was founded in 2006 with co-founders who include director Olav Bergheim; California Institute of Technology professor Morteza Ghari; retired dentist Erik Hars; and Bill Nieman. As President and CEO, Bjarne Bergheim collaborates with a scientific advisory board that includes Scott Arne, DDS, FAGD; Gerald Glickman, DDS; Markus Haapasalo, DDS, PhD; and Ove Peters, DMD, MS, PhD. So·nen·do: a revolutionary company that aims to redefine and transform traditional root canal therapy. SEM showing apical cleaning with Sonendo’s Ultracleaning ™ System SEM showing dentin tubules cleaned with Sonendo’s Ultracleaning ™ System SEM showing dentin tubules cleaned with Sonendo’s Ultracleaning ™ System Multisonic Ultracleaning ™ The Multisonic Ultracleaning System, currently scheduled to debut at the 2014 AAE Annual Session, is designed to be a disruptive technology that uses a mixture of irrigating fluids and sound waves to clean inside the roots of teeth. It quickly, easily, and safely loosens and removes all the pulp tissue, debris, decay, and bacteria from the entire root canal system within minutes. The system is designed to automatically and simultaneously clean all canals in about 5 minutes, as well as improve the clinical quality and business performance of root canal therapy. New paradigm Sonendo’s design goals allow for little to no traditional instrumentation (endodontic file) required, with procedure time dramatically reduced. The Multisonic Ultracleaning System does not remove structural dentin, preserving the structural integrity of the tooth. Sonendo is focused to bring to market a device that will provide an end- odontic treatment that is highly predictable for every procedure, more comfortable for the patient, faster and more efficient for the practice, offering a significant cleaner and disinfected treatment area compared to current standards. Sonendo’s system is not yet commer- cially available for sale or distribution. For more information, visit www.sonendo.com. This information was provided by Sonendo. EP CLINICAL Volume 7 Number 1 Endodontic practice 7 Introduction A key factor affecting the success of endodontic treatment is the establishment of an accurate root canal working length. The ideal cleaning, shaping, and disinfection of the root canal system depends on the accurate determination of the root canal anatomy from canal orifice to the canal-dentinal-cement (CDC) junction. The apical anatomy of root canals has been investigated in several research studies and review articles (Kuttler, 1955; Ricucci, 1998; Green, 1956; Pineda, Kuttler, 1972). The apical CDC junction, also defined as the minor diameter, is the anatomical landmark that segregates the pulp tissue from periodontal tissues. Dummer, et al., described the morphological variations of apical CDC junctions in 1984. Many of these variations cannot be determined radiographically. The distance between the major diameter and the minor diameter of the apex can vary, but usually it is between 0.5 mm to 1 mm (Ricucci, 1998; Green, 1956; Pineda, Kuttler 1972). To preserve the vitality of the periapical tissues, the ideal cleaning, shaping, and root canal filling materials have to be limited to the apical CDC junction. Therefore, it has become the preferred landmark for the apical endpoint for root canal therapy (Nekoofar, et al., 2002). Procedural errors — such as over- instrumentation or under-instrumentation — can occur because of inaccurate estimates of root canal length. Over-instrumentation can damage the anatomy of the root end and also injure the periodontal tissues. On the other hand, under-instrumentation may create a suitable environment for bacteria that might cause a less favorable outcome of the endodontic treatment. Therefore, the accurate determination of the working length is an important goal for the success of the root canal treatment. Several methods can be used to measure the root canal working length. Radiographs can visualize the root canal but are limited to two dimensions and are technique-sensitive to operator inputs (Cox, et al., 1991). A study by Brunton, et al., (2002) showed that electronic apex locators (EALs) could be used to reduce the radiation exposure time to the patients by requiring less radiographs. Some studies found that there were no significant differences between the accuracy of EALs and radiographs (Hoer, Attin, 2004; Vieyra, Acosta, 2011). A study by Real, et al., (2011) found that EALs were significantly more accurate than digital sensors. The use of EALs for determining the root canal working length has become an indispensable part of endodontic treatment. More accurate EALs have evolved in recent years by improving the basic principles upon which the measurements are performed. In 1918, Custer proposed the development of electronic devices to determine the working length. In 1942, Suzuki presented the first generation of EAL to use the electrical resistance properties of the root canal to determine its working length. Sunada (1962) determined the electrical resistance value constantly at 6.5 ohms. This theory considered the electrical resistance between the oral tissues and the periodontal ligament to remain constant. The second generation of EAL had the peculiarity of working with impedance principles. An example of the third- generation EAL is the Root ZX ® (J. Morita) which worked with a constant frequency principle. A fourth-generation EAL was created by Gordon and Chandler (2004), which worked with multiple frequencies. The first version of Root ZX EAL used the average measurements of two frequencies of 0.4kHz and 8kHz. Kobayashi and Suda (1994) described this method as the EAL frequency ratio. The most recent version of Root ZX uses multiple frequencies and can be classified as a fourth-generation EAL (Kobayashi, Suda, 1994). The fifth generation of EAL also uses multiple frequencies, in addition to calculating the root mean square (RMS) values of the electric signals. The RMS represents the energy of the electric signals, and therefore, it is claimed to be less affected by electrical noises affecting other physical parameters such as amplitude or phase of electrical signal that are used by other EALs. An example of a fifth-generation EAL is the Propex Pixi ™ , which is a newer version of recently designed EAL Propex (Dentsply Maillefer, Switzerland). Accuracy of a new apex locator in ex-vivo teeth using scanning electron microscopy Drs. Maria Bonilla, Taner Cem Sayin, Brenda Schobert, and Patrick Hardigan compare the accuracy of root canal working lengths in 200 ex-vivo teeth determined using a fourth-generation electronic apex locator and a new fifth-generation electronic apex locator Figure 1: Apical portion of the specimen Maria Bonilla, DDS, CAGS, works at the Department of Endodontics, Nova Southeastern University, College of Dental Medicine, Fort Lauderdale, Florida. Taner Cem Sayin, DDS, PhD, is an associate professor at the Department of Endodontics, Nova Southeastern University, College of Dental Medicine, Fort Lauderdale, Florida. Brenda Schobert, DDS, CAGS, works at the Department of Endodontics, Nova Southeastern University, College of Dental Medicine, Fort Lauderdale, Florida. Patrick C. Hardigan, PhD, is a professor of public health at the Department of Endodontics, Nova Southeastern University, College of Dental Medicine, Fort Lauderdale, Florida. 8 Endodontic practice Volume 7 Number 1 CLINICAL Aims and objectives The aim of this study was to compare the accuracy of root canal working lengths in 200 ex-vivo teeth determined using a fourth-generation EAL (the Root ZX II) with a fifth-generation EAL (the Propex Pixi). The Propex Pixi and Root ZX II use signals at two different frequencies to calculate the file tip position relatively to root apex. Furthermore, the technology utilized in Propex Pixi differs from the technology used in Root ZX II: Propex Pixi by measuring the RMS of the electric signal, which is further used for calculations. Because of these technology differences, there is a need to compare the accuracy of the Propex Pixi with the Root ZX II to determine root canal working lengths. Materials and methods After IRB approval was obtained, an archive of 200 sound human permanent teeth with completely formed apices was used in this study. The teeth were disinfected by submerging them in a 6% sodium hypochlorite (NaOCl) solution for 15 minutes. They were then rinsed for 10 minutes with distilled water. This disinfection cycle was repeated 3 times for each tooth. The teeth were stored in 20- ml sterile scintillation vials filled with distilled water in a refrigerator at 5ºC until use. Prior to inclusion in this study, the root surfaces and apices of each tooth were examined under x16 magnification using a surgical microscope (Global Surgical Corp.) for a possible fracture or resorptive areas. If any defects were observed in a tooth, it was discarded from this study. The outer surfaces of the teeth were cleaned by removing tissues with a 15c scalpel (Aspen Surgical). Photographs were taken of each tooth in a buccolingual as well as a mesiodistal view (Figure 1). Digital radiographs (Schick Technologies) for each tooth in a buccolingual and a mesiodistal direction were also taken as pre-operatory procedure (Figure 2). Access cavities were prepared with a high-speed handpiece and a fissure bur (Maillefer, Switzerland) with water coolant, under the surgical operating microscope. Pre-flaring of the root canals was not performed. The root canals were irrigated with 6% NaOCl before the introduction of any file. Patency was established by introducing a No. 6 or No. 8 hand file (Maillefer, Switzerland) until it emerged in the apical foramen, and this was corroborated by visualization using the surgical microscope. Each of the teeth was embedded in a dental device for training purposes with alginate. The 200 teeth were randomly assigned to the Propex Pixi (n = 100) group or the Root ZX II (J. Morita) (n = 100) group. The root canal working length measurements were carried out according to the manufacturers’ instructions. The lip clip electrode was attached to the device, and the other electrode was attached to a file that fit snugly in the apical portion of the root canal. Digital radiographs for each tooth in a buccolingual and a mesiodistal direction were taken to corroborate radiographically that the working length had been established. The files were then withdrawn from the canals to measure them with an endodontic ruler (Maillefer, Switzerland). The reference points were marked with silicone stoppers. All the working lengths were measured using the same endodontic ruler. The working lengths were recorded on a spreadsheet. The files were reinserted into the root canal and cemented with a flowable composite resin to avoid any movements from within the root canal. The apical 4-mm portion of the root canals was carefully shaved in a longitudinal direction using a fine diamond bur (Maillefer, Switzerland) and a scalpel under a Olympus SZX7 ® stereomicroscope at x8 magnification to prevent touching the files with the diamond bur. The apical portion of the teeth and files were observed in micrographs at x40 magnification using an FEI Quanta 200 FEG Environmental Scanning Electron Microscope in the low-vacuum mode, and the distance from the file tip to the CDC junction was measured with Scandium image software (FEI Company) (Figure 3). A Welch’s t-test test was used to compare the accuracy of the working lengths determined by the two EALs at a significance level of P<.05. Results The mean distance from the final working length to the file tip was 0.21 ± 0.25 mm for the Propex Pixi EAL while it was 0.08 ± 0.22 mm for the Root ZX II EAL (Table 1, Figure 2). A difference of 0.13 mm (95%: 0.23 to 0.47) was found between the Propex Pixi and Root ZX II EALs. The Propex Pixi was accurate 88% of the time to ± 0.5 mm and 98% accurate within ± 1.00 mm (Table 2). The Root ZX II was accurate 97% of the time to ±0.50 mm and 99% accurate within ±1.00 mm (Table 2). There was no significant difference in the accuracy of the working lengths determined by the two EALs (P > 0.05). Discussion This study is the first to investigate the accuracy of the root canal working length measurements of a new fifth-generation EAL called the Propex Pixi. Given the importance of accurate root canal working length measurements to the outcome of Figure 2: The mean distance from the final working length to the file tip [...]... Ni-Ti engine-driven, and K-Flex endodontic instruments J Endod 1995;21(3):146-151 Gutmann JL, Gao Y Alteration in the inherent metallic and surface properties of nickel-titanium root canal instruments to enhance performance, durability and safety: a focused review Int Endod J 2012;45(2):113128 Johnson E, Lloyd A, Kuttler S, Namerow K Comparison between a novel nickel-titanium alloy and 508 nitinol on the... hydrogen peroxide in protein turnover, DNA synthesis, and RNA synthesis Basic Life Sci 1988;49:829-832 Park JW, Floyd RA Glutathione/Fe3+/O2-mediated DNA strand breaks and 8-hydroxydeoxyguanosine formation Enhancement by copper, zinc superoxide dismutase Biochim Biophys Acta 1997;1336(2):263268 Rotstein I, Zalkind M, Mor C, Tarabeah A, Friedman S In vitro efficacy of sodium perborate preparations used for . Max (mm) PIXI 10 0 0. 21 0.25 -0.40 1. 27 Root ZX 10 0 0.08 0.22 -0. 87 1. 04 Difference NA 0 .13 0.03 0.23 0. 47 Table 1: Descriptive statistics per locator device PIXI (N =10 0) Root ZX (N =10 0) Distance. 8% 13 13 % 0. 01 to 0.50 80 80% 84 84% 0.50 to 1. 00 10 10 % 2 2% Greater then 1. 00 2 2% 1 1% Table 2: Frequency of distance from working length per locater device 10 Endodontic practice Volume 7. J. 2006;39(5):408- 414 . Pineda F, Kuttler Y. Mesiodistal and buccolingual roentgenographic investigation of 7, 275 root canals. Oral Surg Oral Med Oral Pathol. 1 972 ;33 (1) :10 1 -11 0. Real DG, Davidowicz