Efficacy of Multiple Rotary File Systems in Retreatment of Oval-shaped Root Canals in Mandibular Molars: A Cone-Beam Computed Tomography Study

Abstract

Aim: To evaluate effectiveness of multiple rotary file systems on removal of the filling materials during retreatment of oval-shaped root canals.Methods: 40 oval root canals were instrumented with ProTaper Next to size X4 (40/.06). The canals were then allocated into two equal groups according to the final rinse, Group I: with Biopure MTAD, and Group II: with 17% EDTA. All the canals were later obturated with bioceramic based root canal sealer and gutta-percha using cold lateral compaction technique. According to the used retreatment rotary system, each group were further subdivided into two equal subgroups including subgroups Ia & IIa using D-Race (DR1) (30/.10) + XP-endo Shaper (XPS) (30/.04) + XP-endo Finisher R (XPFR), and subgroups Ib & IIb using R-Endo retreatment files up to R3 (25/.04) + Revo-S rotary files up to (40/.06). CBCT scans were used to calculate the remaining amount of root filling materials based on a certain threshold given to identify the density of dentin from that of the gutta percha at the pre scan (after obturation), and that of air at the post scan (after retreatment). The dentin volumes were also recorded at both scans to analyze the amount of remaining filling materials.Results: No significant differences were recorded regarding the amount of residual filling material with the tested systems (p > 0.05). Intra subgroups assessments showed more filling material removed when using a larger sized final instrument (p < 0.001).Conclusions: Tested file systems were evenly efficient in removing filling materials from ovalshaped root canals of extracted molars. Types of chelators used and bioceramic based sealer had no significant validity on effectiveness of removal of root canal filling material.