Efficacy of two rotary file systems in gutta percha removal from extracted maxillary molars for retreatment: a three-dimensional volumetric analysis using cone beam computed tomogrpahy

Ideally, an instrument for endodontic retreatment should allow for complete gutta- percha (GP) removal in a short period of time as well as no instrument separation to occur. The contaminated residues of gutta-percha and sealer appear to restrict the passage of the irrigants to the dentinal tubules, particularly in cases of non surgical root canal retreatment (NS-RCRT) with anatomical variances. Therefore, any interference between the dentin and the irrigants should be minimized to ensure maximum irrigation efficiency. This study aims to investigate the efficacy of XP-endo Shaper, Edgefile XR, and Hedstrom files in NS-RCRT evaluated using Cone Beam Computed Tomography (CBCT). A total of 45 extracted teeth of maxillary molars were instrumented and obturated. Preoperative CBCT scans were obtained, and the teeth were retreated using Edgefile XR, XP Shaper, and Hedstrom files (n=15 teeth per group). After retreatment, the teeth were rescanned, and three-dimensional images were constructed to assess the percentage volume of remaining root canal filling material. The total time for retreatment was recorded, and the data were analyzed statistically. As a result, the XP Shaper demonstrated significantly greater percentage removal of gutta-percha compared to the EdgeFile XR group. The distobuccal (DB) canal exhibited the lowest percentage of remaining material in comparison to the mesiobuccal (MB) canal, while no significant difference was observed when compared to the palatal (P) canal. Among the instruments tested, the Hedström file required the longest duration to complete retreatment. In conclusion, root canal filling was efficiently removed using the XP Shaper compared to Edgefile XR instruments however there was no significant difference compare to hand files. The XP Shaper and Edgefile XR are shown to be advantageous over hand files in terms of operating time.