Evaluation of the mechanical properties of three new root canal instruments

Aim: This study compared the mechanical properties of ProTaper Next, ProFile Vortex and OneShape instruments. Materials and methods: The instruments were subjected to mechanical tests to evaluate microhardness, cyclic fatigue, resistance to bending and torsional load in a clockwise rotation. Analysis of variance (ANOVA) and the Student-Newman-Keuls test for multiple comparisons were employed to evaluate the data. Results: In the bending resistance test, significant differences were observed when comparing both ProTaper Next and ProFile Vortex to OneShape (P 0.05), however there was no significant difference between ProTaper Next and ProFile Vortex (P > 0.05). OneShape's bending resistance was found to be significantly higher. In the fatigue resistance test, ProTaper Next was found to be most resistant, followed by OneShape then ProFile Vortex. Statistical analysis suggests a significant difference in angular deflection at failure between all instruments tested (P 0.05). Considering maximum torque, significant differences were found between ProFile Vortex and OneShape, and between Pro- Taper Next and OneShape (P 0.05), however there was no significant difference between ProFile Vortex and ProTaper Next instruments (P > 0.05). Maximum torque was significantly higher for One- Shape. Vickers microhardness did not differ significantly amongst all instruments tested (P > 0.05). Conclusion: The ProTaper Next instruments were found to be the most flexible and most resistant to cyclic fatigue while the OneShape instruments outperformed the others when evaluating deflection at failure and maximum torque. Parole chiave: bending resistance, cyclic fatigue, flexibility, M-Wire, nickel-titanium alloy, torsional resistance