(PO23) Micro-Computed Tomographic Evaluation of Morphological Changes, Canal Transportation, and Centering Ability of Continuous Rotation vs. Reciprocating Motion

Abstract: The aim of the study was to evaluate and compare the shaping ability of the One Curve Mini (OCM) and One Reci (OR) file systems on extracted maxillary premolars using micro-computed tomography. A total of 22 maxillary premolars containing 2 separate canals (n=44) were divided randomly to assign the samples into 2 experimental groups: One Reci 25/.06 (MicroMega, Besancon, France) (n=22) and One Curve Mini 25/0.06 (MicroMega, Besancon, France) (n=22). Pre- and post-instrumentation micro-CT scans were analyzed to measure the following parameters: percentage of untouched canal surface area, dentin thickness, transportation, centering ability, canal volume, structural model index (SMI), and canal angulation. Statistical analysis was conducted with the significance level set at p<.05. Comparison between both groups showed no significant changes in SMI, dentin thickness, surface area, volume, and transportation after canal instrumentation (p>.05). The mean untouched surface wall was significantly higher in the OR file system in the apical area compared to the OCM file system. OCM had a significantly higher centering ratio than the OR group at the 1 mm level. In contrast, the OR group showed a significantly higher centering ratio than the OCM group at the 5 mm level. Finally, in post-instrumentation angulation, less canal curvature was observed in the OR group than in the OCM group, with statistical significance. Within the limitations of this study, it can be concluded that reciprocating and rotational motion are similar in their shaping abilities. Both OCM and OR files showed comparable root canal preparation and are considered safe to use in curved canals without causing significant transportation or mishaps.