Rotary Systems: An Insight

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1 REVIEW ARTICLE Rotary Systems: An Insight 1 Manmohan R Soni, 2 Swaroop Hegde, 3 Sylvia Mathew, 4 K S Madhu 1 Post-graduate Student, Department of Conservative Dentistry and Endodontics, Faculty of Dental Sciences, MS Ramaiah University of Applied Sciences, Bengaluru, Karnataka, India. 2 Professor, Department of Conservative Dentistry and Endodontics, Faculty of Dental Sciences, MS Ramaiah University of Applied Sciences, Bengaluru, Karnataka, India. 3 Professor & Head, Department of Conservative Dentistry and Endodontics, Faculty of Dental Sciences, MS Ramaiah University of Applied Sciences, Bengaluru, Karnataka, India. 4 Assistant Professor, Department of Conservative Dentistry and Endodontics, Faculty of Dental Sciences, MS Ramaiah University of Applied Sciences, Bengaluru, Karnataka, India. Correspondence: Dr. Manmohan R Soni. Department of Conservative Dentistry and Endodontics, Faculty of Dental Sciences, MS Ramaiah University of Applied Sciences, M.S.R.I.T. Post, M.S.R. Nagar, Bengaluru , Karnataka, India. Mobile: mansoni06@gmail.com How to Cite: Soni MR, Hegde S, Mathew S, Madhu KS. Rotary systems: An insight. J Dent Orofac Res 2014;10(2): ABSTRACT In modern day practice, with time being the essence, it has become a necessity to strive for newer advances in technology. Keeping this in mind utmost patient benefit is the prime goal for an endodontist. Successful endodontic treatment relies upon endodontic instruments used for cleaning and shaping of the root canal system, which ultimately determines the clinical outcome. Rotary systems have proved to be safer, quicker and more efficient over the conventional instruments. The modern day dental surgeon is faced with the challenge of using the best rotary system among the plethora of systems available. This review gives a brief insight into the design and features of different rotary instrument systems. Key Words: Nickel titanium, root canal preparation, rotary instruments. Introduction Success in modern day endodontics is based on various principles comprising of diagnosis and treatment planning, knowledge of anatomy and morphology, thorough debridement of the root canal system, mechanical preparation of root canal along with chemical disinfection and three-dimensional obturation, followed by the coronal restoration. 1 In order to facilitate the obturation of root canal system, adequate shaping of root canal is necessary. Endodontic instruments play a significant role in the success of endodontic treatment starting from the preparation of the access cavity to the final obturation of the root canal space. 2 A continuously tapering funnel shape with the smallest diameter at the end point and the largest at the orifice has been deemed to be the most appropriate canal shape for filling with gutta-percha and sealer. 3,4 Since the introduction of the first rotating nickel-titanium (NiTi) files for the preparation of the root canal systems in endodontics, the domain of endodontics has changed. 5 Their increased flexibility, shape and memory, potentially allows shaping of narrow-curved canals without causing aberrations. 6 These files also show superior resistance to torsional fracture due to higher ductility. The variety of rotary instruments for endodontic treatment is staggering. There has been a constant quest for quicker, safer and effective instruments for the treatment protocol. Each system has been introduced with benefits, which are apparent in their near perfection in root canal preparation. In order to improve the efficiency and reduce the limitations of these existing systems, manufacturers keep bringing up new instruments or modifications from time to time. Hence, there is a need for standardization of rotary NiTi instrument systems. 7,8 In addition, the increasing NiTi file fracture rate has also posed a challenge for the clinicians. 9 Nonetheless, understanding the basic features of these various systems will help the practitioners to use these instruments effectively and significantly reduce the errors. Thus, this article tries to throw some light on the various rotary systems commonly used in the present day scenario. We have Received: 15 May 14 Accepted: 20 August 14 Conflict of Interest: None 16

2 Instrument system Manufacturer/ year LightSpeed (LSX) LightSpeed Endodontics, San Antonio TX/1992 Profile Dentsply Tulsa Dental/1993 Quantec SC, Sybron LX Endo/1996 GT files Dentsply Tulsa Dental/1998 HERO 642 MicroMega/ 1999 RaCe FKG, Switzerland/1999 Flexmaster VDW Munich Germany/2000 ProTaper Dentsply Tulsa Dental/2001 K3 Sybron Endo/2001 M two VDW, Munich, Germany/2003 Twisted file Sybron Endo, Orange, CA, Selfadjusting file USA/2008 ReDent, Raanana, Israel/2010 Hyflex Coltene Endo/2011 Introduced by Wildey & Senia Table 1: The design features of the commonly used rotary files. Cross section/ transverse Rake angle Helical angle Cutting surface Tip design Sizes Taper (%) Speed (rpm) section Triple U shape Neutral N/A 3 radial lands Non active N/A Ben Johnson Triple U shape Negative (20 ) Open (20 ) 3 radial lands Non active , 4, 5, 6, 7, 8 McSpadden S shaped design Positive Close 2 radial lands Active (SC) non active (LX) Buchanan Triple U shape Neutral Variable , 3, 4, 5, 6, 8, 10, radial lands Non active , 8, 10, Daryl Green Triangular Positive Open 3 cutting blades Non active , 4, Triangular or square Negative Variable and alternated 3 or 4 cutting blades Non active , 4, 6, 8, Triangular Positive 3 cutting blades Non active , 4, 6, P Machtou, C Ruddle, J West Convex triangular McSpadden 3 asymmetric surfaces Negative Variable Positive Variable Italic S Negative Variable 3 cutting blades Non active Variable: Sx , S1 2 11, S , F , F , F radial lands, 1 cutting blade Non active , cutting blades Non active , 5, 6, Triangular Variable 2 cutting blades Non active , 6, 8, 10, Zvi Metzger NiTi lattice N/A N/A Hollow thin walled cylinder Riacrdo Caiecedo, Stephen Clark Double fluted Hedstroem design Positive Variable, accelerated flute design 2 cutting blades, no radial lands Non active (Asymmetrical) 1.5 and 2 mm (diameter) Non active , 6, (Contd..) 17

3 Table 1: (Continued...) Speed (rpm) Rake angle Helical angle Cutting surface Tip design Sizes Taper (%) Cross section/ transverse section Introduced by Manufacturer/ year Instrument system 3 cutting blades Non active , Negative Variable Modified convex triangular cross section Wave one Dentsply Tulsa Dental/ cutting blades Non active , 6, Double S shaped Negative Variable Reciproc VDW GmbH, Munich, 300 Active Variable X1 4, X2 6, X3 7, X4 6, X5 6 Variable 4 cutting blades (2 active at a time) with radial lands Rectangular (offset design) Ricardo Machado Germany/2011 Dentsply Tulsa Dental/2013 ProTaper Next Non active , Edge File Edge Endo/2013 Parabolic cross section (annealed heat treated) NiTi: Nickel titanium, GT: Greater taper Table 2: Cross sectional design of various rotary systems. Instrument system Cross sectional design ProFile GT LightSpeed Protaper WaveOne Hero 642 Flex Master K3 RaCe Twisted file Hyflex CM M two Reciproc Quantec GT: Greater taper Triple U shaped with radial lands Convex triangular, no radial lands Triangular shape, positive rake angle, no radial lands Positive rake angle, three radial lands with peripheral blade relief Triangular shape, no radial lands Double fluted hedstroem design S shaped design, no radial lands tried to compare the various systems based upon their design features (Tables 1 and 2) Common Design Features of a Rotary File Tip design A rotary cutting instrument may have an active or a non-active tip (Figure 1). Cutting tips on the rotary files make them too aggressive. 31 Active tips: It has cutting edges on its surface and can help to shape the narrow, calcified canals. However, it has a disadvantage of accidental apical perforation or transportation. E.g. Quantec file. 18

4 Non-active tip: No cutting edges present and create a concentric circle at the end of the root. Eg. Profile, ProTaper, M two file, etc. Taper It is the amount of increase in the file diameter with each millimeter along its working surface from the tip toward the file handle. It is a very important feature of the rotary file systems and varies from 2% to 12%. 10,32 Constant taper: Instrument with the same taper but varying apical tip diameters. E.g. Profile system Varying or graduating taper: Instrument with same apical diameter but varying taper (4-12%). E.g. Quantec system Progressive taper: Instrument with progressive taper along the shank. E.g. ProTaper system Figure 1: Tip design (active vs. non-active). Rake angle 31 The rake angle is the angle formed by the cutting edge and a cross-section taken perpendicular to the cutting edge The cutting angle is the angle formed by the cutting edge and the radius when the file is sectioned perpendicular to the cutting edge It can either be positive, negative or neutral (Figure 2). Positive rake angle: If the angle formed by the leading edge and the surface to be cut is obtuse, the rake angle is said to be positive or cutting. E.g. K3, Quantec systems. Negative rake angle: If the angle formed by the leading edge and the surface to be cut is acute, the rake angle is said to be negative or scraping. E.g. Profile, ProTaper, M two, etc. Neutral or zero rake angle: When the face of the blade coincides with the radial line it is said to be neutral or zero rake angle (planing). E.g. LightSpeed, Greater taper (GT) file systems. Figure 2: Rake angle. Radial land 33 It is defined as the surface projecting axially from the central axis as far as the cutting edge between flutes (Figure 3). Functions Reduces the tendency of the file to screw into the canal Reduces transportation of the canal Supports the cutting-edge Limits the depth of cut. Full radial land ProFile, GT. Recessed land Quantec. Modified radial land K3. No radial land ProTaper, Race, Endowave, Hero 642. a b Helical angle 34 It is the angle formed by the cutting edge with the long axis of the file. It can be of two types (Figure 4). c Figure 3: Radial land (RL), (a) full RL, (b) recessed RL, (c) no RL, (d) modified RL. d 19

5 Figure 4: Helical angle. Variable helical angle: Helps in moving debris up the canal and the file will be less likely to screw into the canal. E.g. RaCe, GT files, ProTaper etc. Constant helical angle: It is more prone for debris accumulation, leading to the need for increased torque and potential separation. E.g. Profile, Quantec, etc. Conclusion There has been a dramatic change in endodontics in the past decade or two, thanks to the plethora of newer techniques and materials. But at the same time, there has been a lot of resistance to these new products or techniques. Rotary endodontics in the past few years has evolved tremendously. A broader mind-set is required to accept the newer advances while still adhering to the fundamentals of scientific reasoning and rationalization. Practitioners must always bear in mind that all file systems have their pros and cons, and ultimately clinical experience, handling properties, usage safety, and case outcomes, should decide the fate of a particular design or an instrument. The combination of the use of contemporary available modern devices and files with a solid base of anatomical and biological knowledge will lead to a predictably higher quality of root canal treatment, thus helping to preserve the patient s dentition for several years. At the same time, it is apt to remember that perfection ultimately depends more on the operator than the instruments. Instruments cannot, at any time, replace the nimble and skillful fingers of an endodontist. References 1. Ng YL, Mann V, Rahbaran S, Lewsey J, Gulabivala K. Outcome of primary root canal treatment: Systematic review of the literature - part 1. Effects of study characteristics on probability of success. Int Endod J 2007;40(12): Hulsmann M, Peters OA, Dummer MH. Mechanical preparations of root canals: Shaping goals, techniques and means. Endod Top 2005;10: Hargreaves KM. Cohen s Pathways of the Pulp, 10 th ed. Missouri: Mosby Inc.; Ingle JI, Bakland LK, Baumgatner JC. Endodontics, 6 th ed. Hamilton: BC Decker Inc.; Baumann MA. Nickel-titanium: Options and challenges. Dent Clin North Am 2004;48(1): Thompson SA. An overview of nickel-titanium alloys used in dentistry. Int Endod J 2000;33(4): Ehrmann EH. Wanted: A standard for the recognition of rotary NiTi instruments. Int Endod J 2002;35(2): Vaudt J, Bittr K, Kielbassa AM. Evaluation of rotary root canal instruments in vitro: A review. Endo 2007;1: Sattapan B, Nervo GJ, Palamara JE, Messer HH. Defects in rotary nickel-titanium files after clinical use. J Endod 2000;26(3): Bergmans L, Van Cleynenbreugel J, Beullens M, Wevers M, Van Meerbeek B, Lambrechts P. Smooth flexible versus active tapered shaft design using NiTi rotary instruments. Int Endod J 2002;35(10): Barbakow F. The LightSpeed system. Dent Clin North Am 2004;48(1): Profile Catalogue: Dentsply, Maillefer Instruments Switzerland. Available from: Products/Instructions-for-use.aspx. [Last accessed on 13. Hsu YY, Kim S. The ProFile system. Dent Clin North Am 2004;48(1): Quantec System. Available from: endodonziamauroventuri.it/preparazione%20rotante%20 Ni-Ti/Quantec%20System%20-%20Brochure.pdf. [Last accessed on 15. Bertrand MF, Pizzardini P, Muller M, Médioni E, Rocca JP. The removal of the smear layer using the Quantec system. A study using the scanning electron microscope. Int Endod J 1999;32(3): Buchanan SL. ProSystem GT: Design, technique, and advantages. Endod Top 2005;10: Endodontics with Micro-Mega. Available from: Micro-Mega/micromega_engl.pdf. [Last accessed on 18. Stokes OW, Fiore PM, Barss JT, Koerber A, Gilbert JL, Lautenschlager EP. Corrosion in stainless-steel and nickeltitanium files. J Endod 1999;25(1): FlexMaster the rotary NiTi system for every case. Available from: downloads/produkte/en/en-flexmaster.pdf. [Last accessed on 20. Sonntag D. FlexMaster: A universal system. Endod Top 2005;10: Clauder T, Baumann MA. ProTaper NT system. Dent Clin North Am 2004;48(1): Gambarini G. The K3 rotary nickel titanium instrument system. Endod Top 2005;10: Mounce R. The twisted file: A new paradigm in canal 20

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