Background and Aim: Previous studies have reported inconsistent findings on the effectiveness of endodontic retreatment rotary files for removal of residual filling materials. This study aimed to compare the efficacy of ProTaper, M3, and Edge Endo rotary retreatment systems for removal of root canal filling materials using cone-beam computed tomography (CBCT).
Materials and Methods: This ex vivo experimental study involved mesiobuccal and mesiolingual canals of mandibular molars, and mesiobuccal canals of maxillary molars (n=60) with ≤20-degree curvature. Canals were instrumented with ProTaper files with the crown-down technique, and obturated with gutta-percha and AH26 sealer via cold lateral compaction technique. Specimens were randomly assigned to three groups (n=20) of ProTaper, M3, or Edge Endo. CBCT imaging and AutoCAD software were used to quantify residual filling material in the coronal, middle, and apical thirds, and along the full canal length. Procedural errors, including file fracture, were recorded. Data were analyzed using the Kruskal-Wallis, Mann-Whitney, and Chi-square tests, with a significance level of 0.05.
Results: A statistically significant difference was observed in the apical third (P=0.02), with ProTaper retaining the most (47.11%±24.59%), and M3 the least (28.47%±28.07%) filling material. No significant differences were found in the coronal (P=0.282) and middle thirds (P=0.824). File fracture occurred in 12% of the cases, with no significant difference among the groups (P=0.809).
Conclusion: Based on the results, while residual filling material remained in all canals, the M3 rotary retreatment files demonstrated superior efficiency in cleaning the apical third.