Comparative evaluation of supplementary techniques for filling material removal in oval root canals: a micro-CT...

This study aims to evaluate the effectiveness of different supplementary instrumentation protocols in removing residual gutta-percha and calcium silicate-based sealer from oval-shaped root canals following endodontic retreatment. A total of 52 extracted mandibular molar distal roots with oval-shaped canals were prepared and obturated using gutta-percha and Endosequence BC sealer. Before and after the removal of filling material, the specimens were scanned with micro-CT to establish the baseline volume of residual filling material. The roots were divided into four groups (n = 13), each undergoing a different supplementary procedure: standard needle irrigation (SNI), passive ultrasonic irrigation (PUI), sonic activation (SA), or supplementary instrumentation using the XP-endo Finisher R file (XP-R). Micro-CT scans were repeated to analyse residual filling volumes. Data analysis was performed using one-way ANOVA and post hoc tests, with a significance level set at P < 0.05. The XP-R removed significantly more residual filling material compared to all other techniques (P < 0.05). No significant differences were observed amongst the other supplementary techniques in different root thirds (P > 0.05). None of the procedures completely removed root filling remnants. The use of the XP-R as a supplementary finishing instrument improves the removal of residual filling material from oval-shaped root canals. Complete removal of filling remnants remains challenging, emphasising the need to optimise retreatment protocols for complex canal anatomies.