Effect of Cross-sectional Designs on Torsional Resistance of Endodontic Nickel–Titanium Files: A Finite Element Study

This study identified the <i>re</i> /<i>J</i> ratio and the percentage of inner core area as the most critical design factors influencing the torsional resistance of rotary files. Files with a lower <i>re</i> /<i>J</i> ratio and a larger inner core area experienced lower shear stress, resulting in enhanced torsional resistance and potentially reducing the risk of torsional fracture during use. These findings offer valuable insights for both clinicians selecting rotary files and manufacturers designing future iterations, ultimately contributing to improved safety and efficacy during root canal treatments.