Evaluation of the Flexibility, Cyclic Fatigue, and Torsional Resistance of Rotary Endodontic Files Made of Different Nickel-Titanium Alloys

Aim: This study compared the mechanical properties of Profile Vortex, Profile Vortex Blue, and Race rotary files. Materials and Methods: The files were subjected to flexibility, rotating-bending (static and dynamic), and torsional resistance tests. Results: Analysis of the data obtained was performed using ANOVA and Student-Newman-Keuls tests. Significant difference in flexibility was observed between Profile Vortex Blue and the two other files tested (Profile Vortex M Wire and Race) (P<0.05); however, Profile Vortex M Wire and Race did not significantly differ from each other (P>0.05). In the rotatingbending tests (static and dynamic), Profile Vortex Blue presented significantly greater resistance than Profile Vortex M Wire and Race (P<0.05). As for the torsional resistance test, Profile Vortex M Wire had significantly greater resistance (degrees and turns) than the other two instruments tested (P<0.05). No difference in torsional resistance was observed between Profile Vortex Blue and Race files (P>0.05). Statistical analysis revealed significant differences in maximum torque among the instruments tested, as follows (in decreasing order): Profile Vortex Blue > Profile Vortex M Wire > Race (P<0.05). Conclusion: Profile Vortex Blue files were more flexible, more resistant to rotating-bending fatigue, and to torsional failure when compared to Profile Vortex (made of M-Wire NiTi) and Race files (made of conventional NiTi).