Evaluation of different methods for separated file retrieval from the apical third of curved root canals: In vitro study

Background: This study aimed to evaluate the interaction between different ultrasonic troughing tips and varying retrieval tools in removing separated instruments from the apical third of the mesiobuccal (MB) root canal of maxillary molars, focusing on dentin loss and retrieval time. Methods: Sixty MB canals from extracted human maxillary first molars were used. A size 25/04 Nickel–Titanium file was intentionally fractured beyond the curve. Teeth were randomly assigned according to the troughing method (Ultra-X golden tip vs. ET25 L tip) and retrieval tool (BTR Pen vs. modified tube technique). Cone-beam computed tomography was used to measure dentin thickness before and after retrieval. Statistical analysis used two-way analysis of variance, Tukey’s HSD post hoc test, and Kruskal–Wallis tests ( P < 0.05). Results: ET25 L group paired with the BTR Pen caused the greatest dentin loss (0.3035 ± 0.17 mm), while the ET25 L paired with the tube technique resulted in the least (0.2218 ± 0.13 mm). For retrieval time, the ET25 L tip was significantly faster than the Ultra-X tip ( P < .001), regardless of the retrieval tool used. Conclusions: The ET25 L tip paired with the modified tube technique provides the most conservative and time-efficient approach for retrieving apically separated instruments.