Effectiveness of Two Different File Systems in the Removal of Root Canal Filling Material from Oval-Shaped Canals: A Micro–Computed Tomography Study

Objective This study aimed to compare, using micro–computed tomography (µCT), the effects of the XP-Endo Finisher (XP-EF) and Gentlefile Brush (GFB) files—used as supplementary instrumentation following Ni–Ti retreatment—on the volume of remaining root canal filling material in oval-shaped root canals. Materials and Methods Twenty single-rooted, single-canal mandibular premolars with oval-shaped canals extracted for periodontal or orthodontic reasons were included. The canals were prepared up to size F4 using the ProTaper Universal system, obturated with gutta-percha and AH Plus, and incubated for one month. After initial µCT scanning, the filling material was removed using the ProTaper Universal Retreatment system, and the specimens were allocated into two groups according to the supplementary instrumentation: XP-EF or GFB. A second µCT scan was performed after the additional instrumentation procedures. Results A statistically significant reduction in the volume of filling material was observed in both groups (p < 0.05). However, the volumetric reduction achieved in the XP-EF group was significantly greater than that in the GFB group (p < 0.05). Complete removal of the filling material was not achieved with either method. Conclusion Although both supplementary systems were effective in reducing residual filling material, XP-Endo Finisher demonstrated superior performance in oval-shaped root canals.