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A Paradigm Shift for Torsional Stiffness of Nickel-Titanium Rotary Instruments: A Finite Element Analysis

Published:April 26, 2021DOI:https://doi.org/10.1016/j.joen.2021.04.017

      Abstract

      Introduction

      The aim of this study was to investigate the influence of mass and the polar moment of inertia on the torsional behavior of nickel-titanium rotary instruments to understand which parameter of cross-sectional design had a key role in terms of torsional resistance.

      Methods

      Four different instrument models were designed and meshed using computer-aided engineering software (SolidWorks; Dassault Systems, Waltham, MA). Instrument models shared the same characteristics, except for cross-sectional design; triangle, rectangle, square, and hollow square geometry was selected. Finite element analysis was performed simulating a static torsional test using the FEEPlus internal solver (Solid Works). Von Mises stress and torsional load at fracture were calculated by the software. Linear regression analysis was performed to investigate the relationship of the polar moment of inertia, cross-sectional area, inner core radius, and mass per volume on the torsional resistance of nickel-titanium rotary instruments.

      Results

      The polar moment of inertia positively affected the maximum torsional load with the highest level of correlation (R2 = 0.917). It could be stated that the higher the polar moment of inertia is, the more maximum torsional load at fracture is present. Mass and cross-sectional area had a lower level of correlation compared with the polar moment of inertia (R2 = 0.5533). According to this, 2 instruments with the same mass/mm and/or cross-sectional area could have different torsional resistance.

      Conclusions

      The polar moment of inertia can be considered as the most important cross-sectional factor in determining the torsional resistance of rotary instruments over metal mass and cross-sectional area.

      Key Words

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      References

        • Glossen C.R.
        • Haller R.H.
        • Dove S.B.
        • et al.
        A comparison of root canal preparations using Ni-Ti hand, Ni-Ti engine-driven, and K-Flex endodontic instruments.
        J Endod. 1995; 21: 146-151
        • Madarati A.A.
        • Hunter M.J.
        • Dummer P.M.
        Management of intracanal separated instruments.
        J Endod. 2013; 39: 569-581
        • Sattapan B.
        • Nervo G.J.
        • Palamara J.E.
        • et al.
        Defects in rotary nickel-titanium files after clinical use.
        J Endod. 2000; 26: 161-165
        • Seracchiani M.
        • Miccoli G.
        • Di Nardo D.
        • et al.
        Effect of flexural stress on torsional resistance of NiTi instruments.
        J Endod. 2021; 47: 472-476
        • Parashos P.
        • Messer H.H.
        Rotary NiTi instrument fracture and its consequences.
        J Endod. 2006; 32: 1031-1043
        • Gambarini G.
        • Cicconetti A.
        • Nardo D.D.
        • et al.
        Influence of different heat treatments on torsional and cyclic fatigue resistance of nickel-titanium rotary files: a comparative study.
        Appl Sci. 2020; 10: 5604
        • Baek S.H.
        • Lee C.J.
        • Versluis A.
        • et al.
        Comparison of torsional stiffness of nickel-titanium rotary files with different geometric characteristics.
        J Endod. 2011; 37: 1283-1286
        • Seracchiani M.
        • Miccoli G.
        • Reda R.
        • et al.
        A comprehensive in vitro comparison of mechanical properties of two rotary endodontic instruments.
        World J Dent. 2020; 11: 185-188
        • Camps J.J.
        • Pertot W.J.
        • Levallois B.
        Relationship between file size and stiffness of nickel titanium instruments.
        Endod Dent Traumatol. 1995; 11: 270-273
        • Kim H.C.
        • Kim H.J.
        • Lee C.J.
        • et al.
        Mechanical response of nickel-titanium instruments with different cross-sectional designs during shaping of simulated curved canals.
        Int Endod J. 2009; 42: 593-602
        • Berutti E.
        • Chiandussi G.
        • Gaviglio I.
        • et al.
        Comparative analysis of torsional and bending stresses in two mathematical models of nickel-titanium rotary instruments: ProTaper versus ProFile.
        J Endod. 2003; 29: 15-19
        • Xu X.
        • Eng M.
        • Zheng Y.
        • et al.
        Comparative study of torsional and bending properties for six models of nickel-titanium root canal instruments with different cross-sections.
        J Endod. 2006; 32: 372-375
        • Grande N.M.
        • Plotino G.
        • Pecci R.
        • et al.
        Cyclic fatigue resistance and three-dimensional analysis of instruments from two nickel-titanium rotary systems.
        Int Endod J. 2006; 39: 755-763
        • Wang G.Z.
        A finite element analysis of evolution of stress-strain and martensite transformation in front of a notch in shape memory alloy NiTi.
        Mater Sci Eng A. 2007; 460-461: 383-391
        • Rumpf H.
        • Boese M.
        • Winzek B.
        • et al.
        SMST-2003: Proceedings of the International Conference on Shape Memory and Superelastic Technologies.
        International Organization on SMST, Pacific Grove, CA2003: 693-700
        • Abu-Tahun I.H.
        • Ha J.H.
        • Kwak S.W.
        • et al.
        Evaluation of dynamic and static torsional resistances of nickel-titanium rotary instruments.
        J Dent Sci. 2018; 13: 207-212
        • Park S.Y.
        • Cheung G.S.
        • Yum J.
        • et al.
        Dynamic torsional resistance of nickel-titanium rotary instruments.
        J Endod. 2010; 36: 1200-1204
        • Friedenberg R.
        “Direct analysis” or "finite element analysis" in biology: a new computer approach.
        Curr Mod Biol. 1969; 3: 89-94
        • Turpin Y.L.
        • Chagneau F.
        • Vulcain J.M.
        Impact of two theoretical cross-sections on torsional and bending stresses of nickel-titanium root canal instrument models.
        J Endod. 2000; 26: 414-417
        • He R.
        • Ni J.
        Design improvement and failure reduction of endodontic files through finite element analysis: application to V-Taper file designs.
        J Endod. 2010; 36: 1552-1557
        • Gambarini G.
        • Seracchiani M.
        • Zanza A.
        • et al.
        Influence of shaft length on torsional behavior of endodontic nickel–titanium instruments. Odontology 2020 Nov 27.
        ([Epub ahead of print])
        • Alapati S.B.
        • Brantley W.A.
        • Svec T.A.
        • et al.
        SEM observations of nickel-titanium rotary endodontic instruments that fractured during clinical use.
        J Endod. 2005; 31: 40-43
        • Kim T.O.
        • Cheung G.S.
        • Lee J.M.
        • et al.
        Stress distribution of three NiTi rotary files under bending and torsional conditions using a mathematic analysis.
        Int Endod J. 2009; 42: 14-21
        • Timoshenko S.P.
        1st ed. Strength of Materials. 261–270. D. Van Nostrand, New York1930: 343-353