Comparison of the effectiveness of various rotary and reciprocating systems with different surface treatments to remove gutta‐percha and an epoxy resin‐based sealer from straight root canals

Aim To compare the Reciproc Blue, Reciproc and ProTaper Universal Retreatment systems with regard to the effective removal of epoxy resin‐based sealer and gutta‐percha during the retreatment of oval, straight root canals. Methodology Forty‐five extracted, human mandibular first premolars with single straight oval canals were selected on the basis of cone beam computed tomography evaluations. The root canals were instrumented with the ProTaper Next system up to the X2 file, and filled with gutta‐percha and epoxy resin‐based sealer using the cold lateral condensation technique. After 1 month, the samples were randomly divided into three groups (n = 15) according to the retreatment system used: Reciproc Blue R40, Reciproc R40 and ProTaper Universal. The specimens were scanned at the resolution of 1.2 μm by a microcomputed tomography device after the root filling and retreatment procedures, and the decrease in the volume of filling material after each retreatment protocol was measured. The results were analysed using the Kruskal–Wallis test and additional box‐and‐whisker plots. Results Although the volume of the filling material decreased significantly in all three groups (P