Shaping Ability of Rotary NiTi Systems in S-Shaped Root Canals of Mandibular Molars.

This study evaluated the shaping ability of HyFlex EDM and Rotate rotary systems in the preparation of S-Shaped mesial root canals of mandibular molars (n = 13). After root canal preparation with instruments HyFlex EDM and Rotate 0.25 and 0.40, the specimens were evaluated for root canal volume, volume increase, static voxels, accumulated hard tissue debris, centring ability and canal transportation. After 0.40 preparation, the Rotate group exhibited a greater increase in volume and less accumulated hard-tissue debris compared to the HyFlex group (p > 0.05). 0.40 preparation with Rotate instruments resulted in greater volume increases across all thirds and less debris in the apical third (p < 0.05). The Rotate group displayed greater transportation and lower centring ability in the apical third after 0.40 preparation (p < 0.05). HyFlex and Rotate demonstrated similar performance up to the 0.25 preparation, and while differences emerged after the 0.40 preparation, both systems provided safe preparation without procedural accidents.