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Open AccessArticle

Ex-Vivo Comparison of Torsional Stress on Nickel–Titanium Instruments Activated by Continuous Rotation or Adaptive Motion

1
Department of Conservative Dentistry, Dental Research Institute, School of Dentistry, Pusan National University, Yangsan 50612, Korea
2
Department of Conservative Dentistry, School of Dentistry, Kyungpook National University, Daegu 41940, Korea
*
Author to whom correspondence should be addressed.
Joo-Yeong Lee and Sang Won Kwak contributed equally to this work and have the first authorship shared.
Materials 2020, 13(8), 1900; https://doi.org/10.3390/ma13081900
Received: 12 March 2020 / Revised: 9 April 2020 / Accepted: 13 April 2020 / Published: 17 April 2020
(This article belongs to the Special Issue Contemporary Endodontic Materials)
This study aimed to evaluate the effect of adaptive motion applied to conventional nickel-titanium (NiTi) rotary instruments on torsional stress generation during shaping procedure. One hundred and twenty mesio-buccal canals of molars were randomly assigned to two groups according to the kinetics; adaptive motion (AD) and continuous rotation (CR). Each group was divided into four subgroups (n = 15) according to the NiTi instrument systems: HyFlex EDM, One Curve, Twisted File Adaptive, and ProTaper Next. A glide path was established with PathFile #1, for each file group being used with either of the kinetic movements. During the instrumentation with the designated motion and file system, the generated torque was measured via the control unit and acquisition module. Based on the acquired data, the maximum and total torque were calculated. The data were statistically analyzed using Kruskal–Wallis and Mann–Whitney tests at a significance level of 95%. The maximum and total torque generated by all instruments were significantly reduced by the adaptive motion (p < 0.05). In the CR group, HyFlex EDM generated the highest maximum and total stress. In the AD group, HyFlex EDM showed the highest maximum torsional stress, and One Curve showed the highest total torsional stress (p < 0.05). The TF Adaptive instrument with adaptive movement produced the lowest maximum and total torsional stress (p < 0.05). Under the conditions of this study, the use of adaptive motion would be useful to reduce the torsional stress of instrument and root dentin. The reduction of torsional stress through adaptive motion may enhance the durability of instruments and reduce the potential risk of dentinal cracks. View Full-Text
Keywords: adaptive motion; continuous rotation; torque generation; torsional stress; kinetics adaptive motion; continuous rotation; torque generation; torsional stress; kinetics
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MDPI and ACS Style

Lee, J.Y.; Kwak, S.W.; Ha, J.-H.; Kim, H.-C. Ex-Vivo Comparison of Torsional Stress on Nickel–Titanium Instruments Activated by Continuous Rotation or Adaptive Motion. Materials 2020, 13, 1900.

AMA Style

Lee JY, Kwak SW, Ha J-H, Kim H-C. Ex-Vivo Comparison of Torsional Stress on Nickel–Titanium Instruments Activated by Continuous Rotation or Adaptive Motion. Materials. 2020; 13(8):1900.

Chicago/Turabian Style

Lee, Joo Y.; Kwak, Sang W.; Ha, Jung-Hong; Kim, Hyeon-Cheol. 2020. "Ex-Vivo Comparison of Torsional Stress on Nickel–Titanium Instruments Activated by Continuous Rotation or Adaptive Motion" Materials 13, no. 8: 1900.

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