Cyclic Fatigue Resistance Of Three Root Canal Ni-Ti Systems

Abstract

The aim of this study was to evaluate the cyclic fatigue resistance of ProTaper rotary files fabricated from traditional Ni-Ti alloy and compare it to Twisted File made from R-Phase Ni-Ti alloy and WaveOne files made from M-wire in both rotation and reciprocation. A total of ninety six endodontic files, thirty two files of each type of file systems were used in this study. Samples were divided into three main groups according to file type and two subgroups according to file motion, each subgroup was divided into two sub divisions according to radius of curvature. Cyclic fatigue device was constructed for this study, the main metal block contains four canals having curvature 600 with two canals having radius of curvature 2mm and other 2 canals having 5mm radius of curvature. Files are allowed to rotate inside the curved canals in both rotation and reciprocation motion and the time to failure was recorded. Statistical analysis was performed with one-way analysis of variance and the Tukey test for individual comparisons (confidence level of P≤ 0.05). Fractured surfaces of broken instruments were also observed under scanning electron microscopy for any defect or deformations observed after testing. Regarding file type the WaveOne file showed cyclic fatigue resistance significantly higher than both Twisted File and ProTaper in both rotation and reciprocation (P<0.001). Regarding motion type, the reciprocating motion showed significant higher fatigue resistance than rotatry motion with all tested files. There was significant higher fatigue resistance for files used in 5mm radius of curvature than files used in 2mm radius of curvature.