Comparison of the mechanical behavior between controlled memory and superelastic nickel-titanium files via finite element analysis.

Introduction: The aim of this study was to evaluate the flexibility and torsional stiffness of a controlled memory (CM) nickel-titanium (NiTi) file and compare its mechanical responses with those of a superelastic NiTi file with the same geometry using finite element simulation.

Methods: A commercially available instrument with a tip size of 30 and a 0.06 taper was selected for this study. The geometric model for finite element analysis was generated by micro-computed tomographic scanning, and the data for the constitutive model of controlled memory NiTi were obtained from the literature. The numeric analysis was performed in ABAQUS (SIMULIA, Providence, RI) with boundary conditions that were based on the ISO 3630-1 specification.

Results: The CM NiTi file exhibited the least bending moment and maximum stress value (523 MPa) under 45° bending simulation. However, the least torsional stiffness was calculated for this same instrument.

Conclusions: The higher flexibility and potential fatigue resistance of the CM NiTi files were confirmed, indicating that this new technology represents an improvement in the mechanical behavior of the rotary NiTi files.