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BioMed Research International
Volume 2017 (2017), Article ID 4528601, 13 pages
Research Article

Mechanical and Metallurgical Properties of Various Nickel-Titanium Rotary Instruments

1White Dental Clinic, Daemyeong Bld, 87 Choonggyeong-ro, Deokyang-gu, GoYang 10529, Republic of Korea
2Department of Conservative Dentistry, Kyung Hee University Dental Hospital, 23 Kyungheedaero, Dongdaemun-gu, Seoul 02447, Republic of Korea
3Department of Conservative Dentistry, Dental Research Institute, Seoul National University Dental Hospital and Seoul Dental Hospital for Disabled, Seoul National University School of Dentistry, 101 Daehawk-Ro, Seoul 03080, Republic of Korea
4Biomedical Research Institute, Korea Institute of Science and Technology, 5 Hwarang-ro 14, Seongbuk-gu, Seoul 02792, Republic of Korea
5Future Convergence Research Division, Korea Institute of Science and Technology, 5 Hwarang-ro 14, Seongbuk-gu, Seoul 02792, Republic of Korea
6Department of Conservative Dentistry, School of Dentistry, Kyung Hee University, 23 Kyungheedaero, Dongdaemun-gu, Seoul 02447, Republic of Korea

Correspondence should be addressed to Seok Woo Chang

Received 30 August 2017; Revised 27 October 2017; Accepted 2 November 2017; Published 28 November 2017

Academic Editor: Hwa-Liang Leo

Copyright © 2017 Kyu-Sang Shim et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The aim of this study was to investigate the effect of thermomechanical treatment on mechanical and metallurgical properties of nickel-titanium (NiTi) rotary instruments. Eight kinds of NiTi rotary instruments with sizes of ISO #25 were selected: ProFile, K3, and One Shape for the conventional alloy; ProTaper NEXT, Reciproc, and WaveOne for the M-wire alloy; HyFlex CM for the controlled memory- (CM-) wire; and TF for the R-phase alloy. Torsional fracture and cyclic fatigue fracture tests were performed. Products underwent a differential scanning calorimetry (DSC) analysis. The CM-wire and R-phase groups had the lowest elastic modulus, followed by the M-wire group. The maximum torque of the M-wire instrument was comparable to that of a conventional instrument, while those of the CM-wire and R-phase instruments were lower. The angular displacement at failure (ADF) for the CM-wire and R-phase instruments was higher than that of conventional instruments, and ADF of the M-wire instruments was lower. The cyclic fatigue resistance of the thermomechanically treated NiTi instruments was higher. DSC plots revealed that NiTi instruments made with the conventional alloy were primarily composed of austenite at room temperature; stable martensite and R-phase were found in thermomechanically treated instruments.