Maamoun Ataya1, Jung-Hong Ha2, Sang Won Kwak3, Ibrahim H Abu-Tahun4, Rashid El Abed1, Hyeon-Cheol Kim5. 1. Endodontic Department, Hamdan Bin Mohammed College of Dental Medicine, Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, United Arab Emirates. 2. Department of Conservative Dentistry, School of Dentistry, Kyungpook National University, Daegu, Korea. 3. Department of Conservative Dentistry, School of Dentistry, Dental Research Institute, Pusan National University, Yangsan, Korea. 4. Department of Conservative Dentistry, School of Dentistry, The University of Jordan, Amman, Jordan. 5. Department of Conservative Dentistry, School of Dentistry, Dental Research Institute, Pusan National University, Yangsan, Korea. Electronic address: golddent@pusan.ac.kr.
Abstract
INTRODUCTION: This study examined whether the use of T-Wire heat treatment enhanced the resistance to torsional force, cyclic fatigue, and bending stiffness of orifice preflaring nickel-titanium instruments. METHODS: Ninety heat-treated OneFlare (OFT; Micro-Mega, Besançon, France) and conventional OneFlare (OFC, Micro-Mega) nickel-titanium files of size #25/.09 with identical geometries were selected (n = 15 per group for each test). Torsional resistance was evaluated through the measurement of ultimate torsional strength, distortion angle, and toughness during rotational loading. Cyclic fatigue resistance was evaluated through measurement of the number of cycles to failure for each instrument. Stiffness was evaluated by observation of the bending moment on attaining a 45° bend. Independent t tests were performed for statistical analysis. After torsional and cyclic fatigue tests, all fractured fragments were examined under a field emission scanning electron microscope to observe characteristics of the fractured surfaces. RESULTS: OFT showed better cyclic fatigue resistance and lower bending stiffness than OFC (P < .05); however, OFT and OFC did not differ significantly in terms of torsional resistance. The fractured cross-sectional surfaces had characteristics typical of cyclic fatigue and torsional fractures. CONCLUSIONS: The OFT instruments made using T-Wire heat treatment had better cyclic fatigue resistance and lower bending stiffness with no decline in torsional strength.
INTRODUCTION: This study examined whether the use of T-Wire heat treatment enhanced the resistance to torsional force, cyclic fatigue, and bending stiffness of orifice preflaring nickel-titanium instruments. METHODS: Ninety heat-treated OneFlare (OFT; Micro-Mega, Besançon, France) and conventional OneFlare (OFC, Micro-Mega) nickel-titanium files of size #25/.09 with identical geometries were selected (n = 15 per group for each test). Torsional resistance was evaluated through the measurement of ultimate torsional strength, distortion angle, and toughness during rotational loading. Cyclic fatigue resistance was evaluated through measurement of the number of cycles to failure for each instrument. Stiffness was evaluated by observation of the bending moment on attaining a 45° bend. Independent t tests were performed for statistical analysis. After torsional and cyclic fatigue tests, all fractured fragments were examined under a field emission scanning electron microscope to observe characteristics of the fractured surfaces. RESULTS: OFT showed better cyclic fatigue resistance and lower bending stiffness than OFC (P < .05); however, OFT and OFC did not differ significantly in terms of torsional resistance. The fractured cross-sectional surfaces had characteristics typical of cyclic fatigue and torsional fractures. CONCLUSIONS: The OFT instruments made using T-Wire heat treatment had better cyclic fatigue resistance and lower bending stiffness with no decline in torsional strength.
Authors: Theodoro Weissheimer; Murilo Alcalde; Julia Barrionuevo Cortez; Ricardo Rosa; Rodrigo Vivan; Pedro Henrique Souza Calefi; Marco Antonio Hungaro Duarte; Marcus Vinicius So Journal: Eur Endod J Date: 2021-12