• At both room temperature and 65 °C, Hyflex EDM and R-phase TF files showed superior cyclic fatigue resistance in simulated S-shaped root canals.
• Heating to 65 °C significantly reduced the cyclic fatigue resistance of most files, except for R-phase TF.
• Fracture patterns were consistent: initial fracture in the apical curvature followed by coronal fracture, with typical fatigue features.
• Temperature-dependent changes in fragment lengths varied among file types, indicating material-specific responses.