A numerical method for predicting the bending fatigue life of NiTi and stainless steel root canal instruments

P>Aim To evaluate the bending fatigue lifetime of nickel-titanium alloy (NiTi) and stainless steel (SS) endodontic files using finite element analysis. Methodology The strain-life approach was adopted and two theoretical geometry profiles, the triangular (TR) and the square cross-sections, were considered. Both low-cycle fatigue (LCF) lifetime and high-cycle fatigue (HCF) lifetime were evaluated. Results The bending fatigue behaviour was affected by the material property and the cross-sectional configuration of the instrument. Both the cross-section factor and material property had a substantial impact on fatigue lifetime. The NiTi material and TR geometry profiles were associated with better fatigue resistance than that of SS and square cross-sections. Conclusions Within the limitations of this study, finite element models were established for endodontic files to prejudge their fatigue lifetime, a tool that would be useful for dentist to prevent premature fatigue fracture of endodontic files.