Comparison of the shaping abilities of three nickel–titanium instrumentation systems using micro-computed tomography

Abstract Background/purpose The purpose of this study was to compare the canal transportation (CTR) and centering ratio (CR) of ProFile (PF), Twisted File (TF), and WaveOne (WO) nickel-titanium instrument systems and evaluate canal volume (CV) and surface area (SA) using micro-computed tomography (CT). Materials and methods Eighteen extracted human mandibular molars with two separate mesial canals were selected. The specimens were randomly divided into three groups of six teeth. Therefore, twelve root canals were allocated for each group ( n = 12): group 1, PF(#30/.06); group 2, TF(#30/.06); group 3, WO (primary) instrument systems. Working lengths were determined 0.5 mm short of the apical foramen. Specimens were scanned before and after root canal preparation. Scanned images were reconstructed and the effects of root canal preparation on the CV and SA were evaluated. Pre- and post-instrumentation cross-sectional images of 1, 3, 5, and 7 mm from the anatomical apex were obtained and the CTR and CR were compared. The data were analyzed by the Kruskal-Wallis test and linear mixed model with Bonferroni's correction. A P < 0.05 was considered to be significant. Results Postoperative canals were larger and had greater SA, although these changes were not statistically significant (P > 0.05). At any levels (1-, 3-, 5-, and 7-mm), no significant difference was found in the amount of CTR among the groups (P > 0.05). At the 1-, 3-, and 7-mm levels there was no significant difference in the CR among the groups (P > 0.05). However, at the 5-mm level, WO group showed significantly smaller CR than PF group (P < 0.05). Conclusion Within the limitations of this study, WO showed smaller CR than PF, which imply that careful use of WO in curved canals is recommended.