Continuous or Reciprocating Endodontic Rotary Files

Transcription

1 Course Number: 214 Continuous or Reciprocating Endodontic Rotary Files Stephen Weeks, DDS, and James Bahcall, DMD, MS Upon successful completion of this CE activity, 2 CE credit hours may be awarded. A Peer-Reviewed CE Activity by Dentistry Today, Inc, is an ADA CERP Recognized Provider. ADA CERP is a service of the American Dental Association to assist dental professionals in indentifying quality providers of continuing dental education. ADA CERP does not approve or endorse individual courses or instructors, nor does it imply acceptance of credit hours by boards of dentistry. Concerns or complaints about a CE provider may be directed to the provider or to ADA CERP at ada.org/goto/cerp. Approved PACE Program Provider FAGD/MAGD Credit Approval does not imply acceptance by a state or provincial board of dentistry or AGD endorsement. June 1, 2015 to May 31, 2018 AGD PACE approval number: Opinions expressed by CE authors are their own and may not reflect those of Dentistry Today. Mention of specific product names does not infer endorsement by Dentistry Today. Information contained in CE articles and courses is not a substitute for sound clinical judgment and accepted standards of care. Participants are urged to contact their state dental boards for continuing education requirements.

2 Continuous or Reciprocating Endodontic Rotary Files Effective Date: 10/01/2017 Expiration Date: 10/01/2020 Learning Objectives: After reading this article, the individual will learn: (1) the differences and similarities between continuous and reciprocating endodontic rotary files and (2) evidence-based considerations to help clinicians choose the best rotary nickel-titanium (NiTi) endodontic file systems for their clinical needs. About the Authors Dr. Weeks earned his doctor of dental surgery degree (1989) and his certificate in endodontics (1994) at the University of Illinois at Chicago College of Dentistry, and is currently a clinical assistant professor there. He serves as a course director for the preclinical and post-doctoral endodontic curriculum. He is one of the leading authorities on endodontic apex locators. He lectures nationally on various endodontic topics. He can be reached via at sweeks@uic.edu. Dr. Bahcall is a clinical associate professor at the University of Illinois at Chicago College of Dentistry. He is a Fellow in both the American and International College of Dentists and is a Diplomate of the American Board of Endodontics. He received his DMD degree from Tufts University School of Dental Medicine in Boston (1986) and his MS degree and certificate in endo dontics from Marquette University School of Dentistry in Milwaukee, Wis (1991). He has been the recipient of outstanding teaching awards, has published numerous scientific articles, and has written chapters for endodontic textbooks. He lectures on endodontics internationally. He can be reached at jbahcall@uic.edu. Disclosure: The authors report no disclosures. Abraham Lincoln s famous quote, The best way to predict the future is to create it, still holds great relevance in today s world. As everyday consumers, we are continually attracted to newer products and services. As healthcare providers, this same thought is translated into the desire to learn about and incorporate new instruments and procedures that will provide patients with better treatment outcomes. As with any new technology, be it consumer or healthcare, there is a technology adoption life cycle. This life cycle is a bell curve that divides people into early adopters, early majority, late majority, or laggards of new technology. 1 Dentists, being trained professionals in the healthcare field, tend not to jump on the latest and greatest instruments and clinical techniques until they have been proven in evidence-based research. Alexander Pope (1688 to 1744) expressed it by saying, Be not the first by whom the new are tried, nor yet the last to lay the old aside. This research can take many years, and that is why the average cycle for adoption in dentistry and medicine can be 5 to 10 years or more. This cycle is no different in deciding what type of adopter clinicians want to be in the case of endodontic files. In this article, it is the authors intent, as both academicians and clinicians, to discuss the differences and similarities between using continuous and reciprocating endodontic rotary files. The goal in providing this information is to help clinicians decide which rotary NiTi file technology best fits their endodontic treatment armamentarium. CONTINUOUS ROTATION NITI FILES Since the introduction of nickel-titanium (NiTi) rotary file instrumentation in the field of endodontics more than 25 years ago, conventional endodontic treatment has become more predictable and efficient. 2 During this time, there has been a paradigm shift (more adopters) in the way clinicians have gone from complete hand filing of canals to almost exclusively all-rotary file canal preparation. Advancements in the manufacturing of NiTi alloy have resulted in its higher flexibility. This higher flexibility alloy allows for improved tracking along curved canals as compared to hand stainless steel (SS) files. A study by Short et al demonstrated that NiTi rotary files were associated with significantly less time taken to complete canal preparation as compared to hand SS files. This study also observed that NiTi files performed better at remaining centered in the canal when compared to SS files. 3 Another study by Kuhn et al determined that NiTi files had less apical transportation when compared to SS files. 4 Reddy et al demonstrated that rotary NiTi instruments extrude significantly less debris apically than SS hand instruments. 5 Rotary NiTi files also help to reduce ledging and zipping of canals during preparation. Zipping is caused when a file creates an irregular area by opening up the apical region away from the curve of the canal. 6 1

3 To date, no file manufacturer has created the perfect or ideal continuous rotation file system. Although each of the file systems currently on the market has its advantages and disadvantages, the combination of selected file systems may provide a more ideal file system for specific clinical situations. This hybrid system will take into account the biological (science) and clinical (observed after obturation of continuous rotary file canal preparation) requirements for state-of-the-art endodontic treatment. Studies have demonstrated that combining various NiTi file preparation systems can address certain shortcomings of current instruments. 7,8 The benefits of using a combination of continuous rotary file instruments from various manufacturers for endodontic therapy promotes their individual strengths and avoids their weaknesses. 9 Figure 1. An example of symmetrical endodontic file reciprocation. RECIPROCATION NITI FILES Although the concept for a reciprocating endodontic file goes back to the late 1960s, 10 most recently, reciprocation in endodontic treatment has gained notoriety once more due to its ability to use NiTi files, instead of SS files, along with the clinical single-file treatment concept. 11 By definition, reciprocation is derived from the Latin verb reciprocare, meaning to move back and forth. Unfortunately, when this definition is applied to endodontic usage, it can become slightly confusing. This is due to the number of file systems currently on the market that promote themselves as reciprocating but actually can vary in clinical back and forth action. In order to help clarify the reciprocating action of NiTi files clinically, we will need to further define rotary instrument reciprocation as symmetrical and asymmetrical reciprocation. Symmetrical reciprocation is defined as file motion that is equal in both directions. An example of this is a 90 symmetrical file motion driven by the reciprocating handpiece. The file will rotate 90 forward and then rotate an equal amount (90 ) in reverse (Figure 1). Asymmetrical reciprocation is defined as file motion such that the forward rotation is greater than the reverse rotation. When a file rotates more in the forward direction than the reverse, it will eventually make a complete forward rotation. An example of this type of reciprocation involves a 150 forward motion alternating with a 30 reverse motion. Since this asymmetric pattern results in a net forward motion of the file, it is said to be progressive (Figure 2). There are several manufactured variations of progressive reciprocation files. Some examples of these progressive file variations are 150 forward/30 reverse, 90 forward/30 reverse, and 180 forward/90 reverse. An interesting feature in some of these file systems is that the forward and reverse directions are the opposite of what most of us are accustomed to using (ie, Wave- One; Reciproc). The WaveOne and Reciproc file systems (Dentsply Sirona Endodontics) have a reverse, or left-hand, helix. There is no difference in the way these files perform, but they must be used in handpieces that are designed to deliver the appropriate direction of motion (clockwise/counterclockwise). THE SINGLE-FILE TECHNIQUE It has always been the Holy Grail of endodontic treatment to use only one single file along with irrigants and medications (ie, sodium hypochlorite, ETDA, etc) to properly clean and shape a root canal system. As seemingly desirable a goal as this may be, even with the introduction of current reciprocating files, it is not possible. The basic dynamics of preparing a canal, with root canal treatment, minimally require the determination of working length with hand files and the use of a continuous rotary file to open up the coronal two thirds to allow a better guide path for the apical one third files and flow of the irrigants (Figure 3). The good news is that, with reciprocation, it is often possible to use one or 2 reciprocating files after the above basic initial canal filing preparations are completed. Although this is not technically 2

4 a single-file technique, it is definitely a reduction in the number of files required to prepare a root canal as compared to using all continuous rotary files. CLINICAL NITI FILE COMPARISON: CONTINUOUS VERSUS RECIPROCATING As with any endodontic file technology, there are advantages and disadvantages in clinical usage. 12 Some of the key parameters in assessing clinical file usage are the removal of canal debris, the transportation and centering ability of a file, apical extrusion of debris, and file separation. In a study by Neves et al, it was demonstrated that reciprocating single-instrument and continuous rotary multiple file systems were both highly effective in reducing the total bacterial count in a root canal system. 12 This study also concluded that both file systems still left approximately half of the tooth with detectable bacteria. In review of the endodontic file literature, there seems to be a consensus among studies that the centering ability and file transportation of reciprocating and continuous rotating files are similar in their ability to stay centered during root canal preparation and have very little, if any, transportation of the canal. 13,14 Although the practice of endodontics requires the clinician to maintain strict length control of files when preparing a root canal system, canal debris can inevitably be pushed out from the canal. This extruded canal debris has been demonstrated to cause periapical inflammation and postoperative flare-ups. 15 A study by Mittal et al compared hand files, continuous rotary files, and reciprocating files in canal debris extrusion. 16 They found that all files tested did result in extrusion of canal debris. This in vitro study reported that hand files exhibited the most debris followed by continuous rotary files and then reciprocating files. Clinically, the apical extrusion of canal debris can lead to post-op complications, Figure 2. An example of asymmetrical endodontic file reciprocation. such as flare-up. The incidence of flare-ups during endodontic treatment has been reported to range between 1.4% and 16%. 17,18 A study by Kherlakian et al demonstrated that reciprocating and continuous rotary file systems were equivalent in regards to post-op pain. 19 One of the main disadvantages of rotary NiTi endodontic files is the incidence of file separation during clinical usage. The 2 main contributing factors of NiTi file separation are cyclic fatigue and torsional stress. 20 Cyclic fatigue occurs when the file is freely rotating in a canal and flexes until fracturing occurs. Usually the file fractures at the point of maximum flexure (clinically, this corresponds to the most curved portion of the root). Torsional stress occurs when the tip or any other portion of the file is locked or bound within a canal while the file shaft continues to rotate. 21 Sattapan et al concluded that torsional failure occurred more frequently than cyclic fatigue file failure. 20 When using NiTi files, prevention of file separation is complicated by the fact that these files rarely demonstrate visible evidence of wear before breakage Iqbal et al found that NiTi rotary files separate 7 times more than hand SS instruments. 25 Alapati et al 24 and Parashos et al 26 reported the fracture incidence of NiTi rotary instruments to be 5.1% and 5.0%, respectively. Although the literature is just beginning to report the incidence of file separation of reciprocating files, early studies have demonstrated that reciprocating files have a low incidence of file separation. 27,28 Currently, there are no reports in the literature that directly compare the incidence of file separation between continuous and reciprocating rotary files. SUMMARY No matter what type of adopter one may be in the technology adoption life cycle as it pertains to endodontic files, one is still required to evaluate the current file literature, become familiar 3

5 with the file technology in vitro (through acrylic blocks and, preferably, extracted teeth), and then integrate it clinically into endodontic treatment if warranted. In the decision to use either continuous or reciprocating endodontic rotary files, it is important for a dentist to understand that there are advantages and disadvantages to both file systems. Although continuous rotary files have numerous evidence-based publications that include clinical testing demonstrating their effectiveness and efficiency in endodontic treatment, they may have a high file separation rate. Continuous rotary files often require a number of files to prepare a root canal system, which can drive up treatment costs, especially when files are used for only single treatments. On the other hand, reciprocating files do not have years of research and are not Figure 3. The basic dynamics of preparing a canal with root canal treatment minimally require the determination of working length with hand files and the use of a continuous rotary file to open up the coronal two thirds to allow a better guide path for the apical one third files and flow of the irrigants. a true single-file technique. However, reciprocating files have demonstrated a low file separation rate, require a reduced number of files to prepare a root canal, and their performance in a canal is similar to that of continuous rotary files.f References 1. Moore GA. Crossing the Chasm: Marketing and Selling High-tech Products to Mainstream Customers. New York, NY: Harper Collins Publishers; 1991: Walia HM, Brantley WA, Gerstein H. An initial investigation of the bending and torsional properties of Nitinol root canal files. J Endod. 1988;14: Short JA, Morgan LA, Baumgartner JC. A comparison of canal centering ability of four instrumentation techniques. J Endod. 1997;23: Kuhn WG, Carnes DL Jr, Clement DJ, et al. Effect of tip design of nickel-titanium and stainless steel files on root canal preparation. J Endod. 1997;23: Reddy SA, Hicks ML. Apical extrusion of debris using two hand and two rotary instrumentation techniques. J Endod. 1998;24: Weine FS. Endodontic Therapy. 6th ed. St. Louis, MO: Mosby; Walsch H. The hybrid concept of nickel-titanium rotary instrumentation. Dent Clin North Am. 2004;48: Card SJ, Sigurdsson A, Orstavik D, et al. The effectiveness of increased apical enlargement in reducing intracanal bacteria. J Endod. 2002;28: Hargreaves KM, Cohen S, eds. Cohen s Pathways of the Pulp. 10th ed. St. Louis, MO: Mosby; Frank AL. An evaluation of the Giromatic endodontic handpiece. Oral Surg Oral Med Oral Pathol. 1967;24: Yared G. Canal preparation using only one Ni-Ti rotary instrument: preliminary observations. Int Endod J. 2008;41: Neves MA, Provenzano JC, Rôças I, et al. Clinical antibacterial effectiveness of root canal preparation with reciprocating single-instrument or continuously rotating multi-instrument systems. J Endod. 2016;42: Gundappa M, Bansal R, Khoriya S, et al. Root canal centering ability of rotary cutting nickel titanium instruments: a meta-analysis. J Conserv Dent. 2014;17: McRay B, Cox TC, Cohenca N, et al. A micro-computed tomography-based comparison of the canal transportation and centering ability of ProTaper Universal rotary and WaveOne reciprocating files. Quintessence Int. 2014;45: Seltzer S, Naidorf IJ. Flare-ups in endodontics: I. Etiological factors. J Endod. 1985;11: Mittal R, Singla MG, Garg A, et al. A comparison of apical bacterial extrusion in manual, ProTaper rotary, and One Shape rotary instrumentation techniques. J Endod. 2015;41: Walton R, Fouad A. Endodontic interappointment flareups: a prospective study of incidence and related factors. J Endod. 1992;18: Imura N, Zuolo ML. Factors associated with endodontic flare-ups: a prospective study. Int Endod J. 1995;28: Kherlakian D, Cunha RS, Ehrhardt IC, et al. Comparison of the incidence of postoperative pain after using 2 reciprocating systems and a continuous rotary system: a prospective randomized clinical trial. J Endod. 2016;42: Sattapan B, Palamara JE, Messer HH. Torque during canal instrumentation using rotary nickel-titanium files. J Endod. 2000;26: Bahcall JK. Remedying and preventing endodontic rotary nickel-titanium (NiTi) file breakage. Compend Contin Educ Dent. 2013;34: Sattapan B, Nervo GJ, Palamara JE, et al. Defects in rotary nickel-titanium files after clinical use. J Endod. 2000;26: Parashos P, Messer HH. Rotary NiTi instrument fracture and its consequences. J Endod. 2006;32: Alapati SB, Brantley WA, Svec TA, et al. SEM observations of nickel-titanium rotary endodontic instruments that fractured during clinical use. J Endod. 2005;31: Iqbal MK, Kohli MR, Kim JS. A retrospective clinical study of incidence of root canal instrument separation in an endodontics graduate program: a PennEndo database study. J Endod. 2006;32: Parashos P, Gordon I, Messer HH. Factors influencing defects of rotary nickel-titanium endodontic instruments after clinical use. J Endod. 2004;30: Cunha RS, Junaid A, Ensinas P, et al. Assessment of the separation incidence of reciprocating WaveOne files: a prospective clinical study. J Endod. 2014;40: Dagna A. Nickel-titanium single-file system in endodontics. J Contemp Dent Pract. 2015;16: Supplemental Reading De-Deus G, Silva EJ, Marins J, et al. Lack of causal relationship between dentinal microcracks and root canal preparation with reciprocation systems. J Endod. 2014;40: Grande NM, Ahmed HM, Cohen S, et al. Current assessment of reciprocation in endodontic preparation: a comprehensive review part I: historic perspectives and current applications. J Endod. 2015;41: Plotino G, Ahmed HM, Grande NM, et al. Current assessment of reciprocation in endodontic preparation: a comprehensive review part II: properties and effectiveness. J Endod. 2015;41:

6 POST EXAMINATION INFORMATION To receive continuing education credit for participation in this educational activity you must complete the program post examination and receive a score of 70% or better. Traditional Completion Option: You may fax or mail your answers with payment to Dentistry Today (see Traditional Completion Information on following page). All information requested must be provided in order to process the program for credit. Be sure to complete your Payment, Personal Certification Information, Answers, and Evaluation forms. Your exam will be graded within 72 hours of receipt. Upon successful completion of the post-exam (70% or higher), a letter of completion will be mailed to the address provided. Online Completion Option: Use this page to review the questions and mark your answers. Return to dentalcetoday.com and sign in. If you have not previously purchased the program, select it from the Online Courses listing and complete the online purchase process. Once purchased, the program will be added to your User History page where a Take Exam link will be provided directly across from the program title. Select the Take Exam link, complete all the program questions and Submit your answers. An immediate grade report will be provided. Upon receiving a passing grade, complete the online evaluation form. Upon submitting the form, your Letter of Completion will be provided immediately for printing. General Program Information: Online users may log in to dentalcetoday.com any time in the future to access previously purchased programs and view or print letters of completion and results. POST EXAMINATION QUESTIONS 1. NiTi rotary endodontic files are associated with significantly less time to complete canal preparation compared to stainless steel (SS) hand files. NiTi files remain better centered in the canal compared to SS hand files. 2. NiTi files have less apical transportation compared to SS hand files. NiTi files extrude significantly more debris apically than SS hand files. 3. Symmetrical reciprocation is defined as file motion that is equal in both directions. Asymmetrical reciprocation is defined as file motion such that the forward rotation is greater than the reverse rotation. 4. If an asymmetric pattern results in a net forward motion of the endodontic file, it is said to be progressive. a. True. b. False. 5. Neves et al demonstrated that reciprocating single-instrument and continuous rotary multiple file systems were both highly effective in reducing the total bacterial count in a root canal system. The study concluded that both file systems removed more than 90% of bacteria in a root canal system. 5

7 6. There seems to be consensus among studies that reciprocating and continuous rotating files are similar in their ability to stay centered during root canal preparation and have very little, if any, transportation of the canal. a. True. b. False. 7. Which file type(s) did Mittal et al find to exhibit the most extrusion of root canal debris? a. Hand files. b. Continuous rotary files. c. Reciprocating files. d. All types of files exhibited equal debris extrusion. 8. Cyclic fatigue of a file occurs when the file is freely rotating in a canal and flexes until fracture occurs. Torsional stress occurs when the tip or other portion of the file is locked or bound within a canal while the file shaft continues to rotate. 9. Iqbal et al found that. a. NiTi files and hand SS files are roughly equal in terms of file separation. b. Hand SS files separate 5 times more frequently than NiTi rotary files. c. NiTi rotary files separate 7 times more frequently than hand SS files. d. None of the above. 10. Early studies demonstrate that reciprocating files have a low incidence of file separation. Currently, there are no reports in the literature that directly compare the incidence of file separation between continuous and reciprocating rotary files. 6

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