The impact of composition, core metal mass and phase transformation behaviour on the dynamic cyclic fatigue of Ni-Ti files at different temperatures
Accepted: 25 February 2022
All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.
Aim: To assess impact of elemental composition, core metal mass and phase transformation behaviour on the dynamic cyclic fatigue resistance of three Ni-Ti rotary files at room and body temperatures.
Methods: Twenty instruments of each system were tested for dynamic cyclic fatigue resistance in a simulated root canal with a 90˚ angle of curvature and a 5-mm radius of curvature at room and body temperature. The core metal mass at the fractured surface of each instrument was calculated by Image J software analysis of SEM images. The energy dispersive X-ray analysis was used to assess file composition. Scanning calorimetry was used to assess the structural phase state and the transformation temperature. One-way analysis of variance (ANOVA) was performed to determine any statistical difference amongst groups. For inter-group comparison, the unpaired t-test was used.
Results: HEDM showed significantly higher TtF and NCF values than AFBS and ZB-F6 instruments, at both temperatures tested. The mean core metal mass was smallest in HEDM followed by AFBS with no statistical difference between them, while ZB-F6 had the significantly largest metal core. EDX analysis showed that all the instruments were mainly composed by nickel and titanium. DSC analysis revealed that HEDM and AFBS exhibited a martensitic phase at body (37˚C) and room temperature (25˚C), whereas ZB-F6 revealed an austenitic phase at body temperature.
Conclusions: Dynamic cyclic fatigue resistance increased when the instruments had less cross-sectional metal mass, less Ni (wt%), a thermally treated surface, and a martensite phase at body temperature.
Sattapan B, Nervo GJ, Palamara JE, Messer HH. Defects in rotary nickel-titanium files after clinical use. J Endod 2000;26:161–5.
Pruett JP, Clement DJ, Carnes DLJ. Cyclic fatigue testing of nickel-titanium endodontic instruments. J Endod 1997;23:77–85.
Gambarini G, Seracchiani M, Piasecki L, et al. Measurement of torque generated during intracanal instrumentation in vivo. Int Endod J 2019;52:737–45.
Saber SE. Factors influencing the fracture of rotary nickel titanium instruments. ENDO 2008;2:273–83.
Ounsi HF, Al-Shalan T, Salameh Z, et al. Quantitative and qualitative elemental analysis of different nickel-titanium rotary instruments by using scanning electron microscopy and energy dispersive spectroscopy. J Endod 2008;34:53–5.
de Vasconcelos RA, Murphy S, Carvalho CAT, et al. Evidence for reduced fatigue resistance of contemporary rotary instruments exposed to body temperature. J Endod 2016;42:782–7.
Dosanjh A, Paurazas S, Askar M. The effect of temperature on cyclic fatigue of nickel-titanium rotary endodontic instruments. J Endod 2017;43:823–6.
Keleş A, Eymirli A, Uyanık O, Nagas E. Influence of static and dynamic cyclic fatigue tests on the lifespan of four reciprocating systems at different temperatures. Int Endod J. 2019;52:880-6.
Pedullà E, Lo Savio F, Boninelli S, et al. Torsional and cyclic fatigue resistance of a new nickel-titanium instrument manufactured by electrical discharge machining. J Endod 2016;42:156–9.
Pedullà E, La Rosa GRM, Virgillito C, et al. Cyclic fatigue resistance of nickel-titanium rotary instruments according to the angle of file access and radius of root canal. J Endod 2020;46:431–6.
Hülsmann M, Donnermeyer D, Schäfer E. A critical appraisal of studies on cyclic fatigue resistance of engine-driven endodontic instruments. Int Endod J 2019;52:1427–45.
Elsewify T, Saber S, Plotino G. Cyclic fatigue resistance of three heat-treated nickel-titanium instruments at simulated body temperature. Saudi Endod J 2020;10:131–6.
Nishjo M, Ebihara A, Tokita D, et al. Evaluation of selected mechanical properties of NiTi rotary glide path files manufactured from controlled memory wires. Dent Mater J 2018;37:549–54.
Özyürek T, Gündoğar M, Uslu G, et al. Cyclic fatigue resistances of Hyflex EDM, WaveOne gold, Reciproc blue and 2shape NiTi rotary files in different artificial canals. Odontology 2018;106:408–13.
Tanomaru-Filho M, Galletti Espir C, Carolina Venção A, et al. Cyclic fatigue resistance of heat-treated nickel-titanium instruments. Iran Endod J 2018;13:312–7.
Tanomaru-Filho M, Espir CG, Venção AC, et al. Cyclic fatigue resistance of heat-treated nickel-titanium instruments. Iran Endod J 2018;13:312–7.
Gündoğar M, Özyürek T. Cyclic fatigue resistance of OneShape, HyFlex EDM, WaveOne Gold, and Reciproc Blue nickel-titanium instruments. J Endod 2017;43:1192–6.
Grande NM, 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;39:755–63.
Craveiro de Melo MC, de Azevedo Bahia MG, Lopes Buono VT. Fatigue resistance of engine-driven rotary nickel-titanium endodontic instruments. J Endod 2002;28:765–9.
Cheung GSP, Darvell BW. Low-cycle fatigue of NiTi rotary instruments of various cross-sectional shapes. Int Endod J 2007;40:626–32.
Testarelli L, Plotino G, Al-Sudani D, et al. Bending properties of a new nickel-titanium alloy with a lower percent by weight of nickel. J Endod 2011;37:1293–5.
Zhou H, Shen Y, Zheng W, et al. Mechanical properties of controlled memory and superelastic nickel-titanium wires used in the manufacture of rotary endodontic instruments. J Endod 2012;38:1535–40.
Huang X, Shen Y, Wei X, Haapasalo M. Fatigue resistance of nickel-titanium instruments exposed to high-concentration hypochlorite. J Endod 2017;43:1847–51.
de Hemptinne F, Slaus G, Vandendael M, et al. Intracanal temperature evolution during endodontic treatment after the injection of room temperature or preheated sodium hypochlorite. J Endod 2015;41:1112–5.
Arias A, Macorra JC, Govindjee S, Peters OA. Correlation between temperature-dependent fatigue resistance and differential scanning calorimetry analysis for 2 contemporary rotary instruments. J Endod 2018;44:630–4.
Shen Y, Zhou HM, Zheng YF, et al. Metallurgical characterization of controlled memory wire nickel-titanium rotary instruments. J Endod 2011;37:1566–71.
Pedullà E, Ambu E, Rovai F, et al. Influence of proper or reciprocating optimum torque reverse kinematics on cyclic fatigue of four single files. J Investig Clin Dent 2019;10:e12409.
Hülsmann M. Research that matters: studies on fatigue of rotary and reciprocating NiTi root canal instruments. Int Endod J 2019;52:1401–2.
Silva EJNL, Martins JNR, Lima CO, et al. Mechanical tests, metallurgical characterization, and shaping ability of nickel-titanium rotary instruments: A Multimethod Research. J Endod 2020;46:1485–94.
Copyright (c) 2022 Mohamed Salah Abdel Aziz Elwakeel, Ahmed Abdel Rahman Hashem , Sarah Hossam Fahmy, Shehabeldin Mohamed Saber, Gianluca Plotino
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
Giornale Italiano di Endodonzia has chosen to apply the Creative Commons Attribution NonCommercial 4.0 International License (CC BY-NC 4.0) to all manuscripts to be published.