Evaluation of Cyclic Fatigue and Bending Resistance of Coronal Preflaring NiTi File Manufactured with Different Heat Treatments

Coronal preflaring NiTi files should possess proper hardness, resistance to fracture and flexibility. This study compared the bending cyclic fatigue of three orifice files. HyFlex EDM Orifice opener (#25/12), CM (#25/08) One Flare (#25/09) were tested (n = 46/instrument). Bending was assessed with stress when perpendicular displacement applied a 3 mm point from file tip, performed at either room temperature (RT, n 10) or body (BT, 10). Cyclic an artificial ceramic root canal RT BT 10), number cycles failure (NCF) obtained. The NCF results analyzed by two-way ANOVA Tukey’s test. Differential scanning calorimetry (DSC) X-ray diffraction (XRD) analyses 3, respectively). exhibited highest resistance, followed (p < 0.05), irrespective temperature. At RT, demonstrated 0.001), while had 0.001). composed austenite martensite according DSC XRD results. measured BT.