Hye-Jin Goo1, Sang Won Kwak1, Jung-Hong Ha2, Eugenio Pedullà3, Hyeon-Cheol Kim4. 1. Department of Conservative Dentistry, School of Dentistry, Dental Research Institute, Pusan National University, Yangsan, Korea. 2. Department of Conservative Dentistry, School of Dentistry, Kyungpook National University, Daegu, Korea. 3. Department of General Surgery and Surgical-Medical Specialties, University of Catania, Catania, Italy. 4. Department of Conservative Dentistry, School of Dentistry, Dental Research Institute, Pusan National University, Yangsan, Korea. Electronic address: golddent@pusan.ac.kr.
Abstract
AIM: The purpose of this study was to compare the bending stiffness, cyclic fatigue, and torsional fracture resistances of heat-treated and conventional nickel-titanium rotary instruments. METHODS: V-Taper 2 (VT2; #25/.08), V-Taper 2H (V2H; #25/.06), Hyflex CM (HCM; #25/.06), HyFlex EDM (HDM; #25/variable taper), and ProTaper Next X2 (PTN; #25/variable taper) were tested. The bending stiffness was measured with the customized device (AEndoS), and the files (n = 15) were fixed at 3 mm from the tip and bent at 45° with respect to their long axis. Cyclic fatigue resistance was tested by pecking and rotating instruments (n = 15) in artificial canal with a 7.8-mm radius and 35° angle of curvature until fracture. The ultimate torsional strength and toughness were estimated by using AEndoS. The file tip of 5 mm was fixed between resin blocks and driven clockwise at 20 rpm until fracture. The results were analyzed by using one-way analysis of variance and Duncan post hoc comparison. The fracture surfaces and longitudinal aspect of each group were examined under the scanning electron microscope. RESULTS: CM-wire instruments had lower bending stiffness than others. HDM showed the highest cyclic fatigue resistance, followed by VTH and HCM (P < .05). VT2 showed the highest ultimate strength, followed by HDM, VTH-PTN, and HCM. HDM and VT2 showed significantly higher toughness than VTH, HCM, and PTN (P < .05). Scanning electron microscope analysis showed typical fractographic features of cyclic fatigue and torsional fractures. CONCLUSIONS: CM-wire instruments showed higher flexibility and cyclic fatigue resistance than M-wire and conventional nickel-titanium instruments. Large cross-sectional area and conventional nickel-titanium showed high torsional resistance.
AIM: The purpose of this study was to compare the bending stiffness, cyclic fatigue, and torsional fracture resistances of heat-treated and conventional nickel-titanium rotary instruments. METHODS: V-Taper 2 (VT2; #25/.08), V-Taper 2H (V2H; #25/.06), Hyflex CM (HCM; #25/.06), HyFlex EDM (HDM; #25/variable taper), and ProTaper Next X2 (PTN; #25/variable taper) were tested. The bending stiffness was measured with the customized device (AEndoS), and the files (n = 15) were fixed at 3 mm from the tip and bent at 45° with respect to their long axis. Cyclic fatigue resistance was tested by pecking and rotating instruments (n = 15) in artificial canal with a 7.8-mm radius and 35° angle of curvature until fracture. The ultimate torsional strength and toughness were estimated by using AEndoS. The file tip of 5 mm was fixed between resin blocks and driven clockwise at 20 rpm until fracture. The results were analyzed by using one-way analysis of variance and Duncan post hoc comparison. The fracture surfaces and longitudinal aspect of each group were examined under the scanning electron microscope. RESULTS: CM-wire instruments had lower bending stiffness than others. HDM showed the highest cyclic fatigue resistance, followed by VTH and HCM (P < .05). VT2 showed the highest ultimate strength, followed by HDM, VTH-PTN, and HCM. HDM and VT2 showed significantly higher toughness than VTH, HCM, and PTN (P < .05). Scanning electron microscope analysis showed typical fractographic features of cyclic fatigue and torsional fractures. CONCLUSIONS: CM-wire instruments showed higher flexibility and cyclic fatigue resistance than M-wire and conventional nickel-titanium instruments. Large cross-sectional area and conventional nickel-titanium showed high torsional resistance.
Authors: Felipe Augusto Restrepo-Restrepo; Viviana Andrea Holguín-Vásquez; Syldana Julieth Cañas-Jiménez; Paula Andrea Villa-Machado; Sara Ochoa-Soto; Claudia Patricia Ossa-Orozco; Sergio Iván Tobón-Arroyave Journal: Dent Res J (Isfahan) Date: 2021-06-22
Authors: Abdullah Alqedairi; Hussam Alfawaz; Bader Abualjadayel; Mohammad Alanazi; Ahmad Alkhalifah; Ahmed Jamleh Journal: BMC Oral Health Date: 2019-06-21 Impact factor: 2.757