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Torsional Resistance of Heat-Treated Nickel-Titanium Instruments under Different Temperature Conditions

Authors :
Hyo Jin Jo
Sang Won Kwak
Hyeon-Cheol Kim
Sung Kyo Kim
Jung-Hong Ha
Source :
Materials, Vol 14, Iss 18, p 5295 (2021)
Publication Year :
2021
Publisher :
MDPI AG, 2021.

Abstract

This study compared the torsional resistance of heat-treated nickel-titanium (NiTi) instruments under different temperature conditions. Four thermomechanically treated single-use NiTi rotary instruments were selected for this study: OneShape (OS), OneCurve (OC), WaveOne Gold (WOG) and HyFlex EDM (HFE). Each instrument was further subdivided by temperature into 2 subgroups. Maximum torque and the distortion angle until fracture occurred were evaluated. Differential scanning calorimetry analysis was performed to measure the phase transformation temperature. Statistical analysis was performed using a two-way ANOVA and t-test (p < 0.05). Fractured fragments were observed using scanning electron microscopy (SEM). The two-way ANOVA showed no significant differences for different temperature conditions. At both room (RT) and body temperature (BT), OS was predominantly austenite while HFE was martensite. OC and WOG were predominantly martensite at RT and mixed phase at BT. At BT, more than half of WOG was martensite, while half of OC was austenite. SEM examination showed no topographical differences between instruments in different temperature groups. In relation to a limitation of this study, there was no difference in torsional resistance of NiTi rotary instruments between the BT and RT conditions. This implies that clinicians do not need to consider a decrease of torsional resistance of heat-treated NiTi instruments at BT.

Details

Language :
English
ISSN :
19961944
Volume :
14
Issue :
18
Database :
Directory of Open Access Journals
Journal :
Materials
Publication Type :
Academic Journal
Accession number :
edsdoj.7015f806e1450481e7e3aa5011e9fc
Document Type :
article
Full Text :
https://doi.org/10.3390/ma14185295