Microcomputed tomographic evaluation of root filling removal techniques in long oval mandibular premolar canals

Abstract This investigation evaluated the efficiency of various root canal filling removal techniques in removing gutta-percha (GP) and iRoot SP sealer in mandibular premolars with long-oval shaped canal using micro-computed tomography (micro-CT). Forty-eight mandibular premolars with long oval canals were prepared using ProTaper Next to size X3 (30/0.06) and filled with gutta-percha and iRoot SP. The study samples were randomly divided into four groups based on removal technique ( n = 12 for each). Group 1 was Pro Taper Universal Retreatment system (PTU Rx), Group 2 was PTU Rx with Xylol, group 3 was PTU Rx with Endo Success Retreatment Kit, ET25 tip and the group 4 was PTU Rx with Xylol and ET25 tip of Endo Success Retreatment Kit. The study samples were scanned before and after the removal of the root canal filling material using a micro-CT. Kruskal–Wallis test with Benjamini–Hochberg control of the false discovery rate across outcomes and Dunn–Bonferroni post-hoc comparisons were used for data analysis ( P = 0.05). The findings revealed no significant differences among the tested groups regarding the amount of residual root filling material or the ability to regain apical patency ( P > 0.05). The apical third retained the greatest amount of filling remnants compared with the middle and coronal thirds ( P < 0.001). Overall, none of the retreatment techniques demonstrated superiority in removing calcium silicate based root filling materials from long oval canals. However, calcium silicate based sealers appear to be negotiable in single, straight root canals.