Shaping Efficiency of Heat-Treated Reciprocating Systems in Mandibular Molars: A Micro-CT Analysis

This study aimed to evaluate untouched canal areas, canal transportation, and centering ability of WaveOne Gold, R-Motion, and Reciproc Blue systems with different apical sizes and tapers using micro-computed tomographic (micro-CT) analysis. Thirty mesial roots of mandibular molars with single curvature were selected and assigned to three groups (n = 10): WaveOne Gold (25/.07v and 35/.06v), R-Motion (25/.06 and 40/.04), and Reciproc Blue (25/.08v and 40/.06v). All canals were prepared in two sequential stages with small and then larger instruments of the same system. Micro-CT scans were performed before, between, and after instrumentation. Reconstructed images (NRecon v.1.6.10, Bruker) were used to assess untouched canal walls, canal transportation, and centering ratio at 3, 5, and 7 mm from the apex. Shapiro–Wilk test was used for normality. One-way ANOVA with Tukey's post hoc test and paired t-tests were applied (α = 5%). Preoperative canal volume and surface area showed no significant differences among groups (p > 0.05). All systems demonstrated similar shaping performance regarding untouched areas, transportation, and centering ability in both preparation stages (p > 0.05). A significant reduction in untouched canal walls was observed after the second preparation stage in all groups (p < 0.05). Despite similar shaping outcomes among systems, the second preparation stage significantly reduced untouched canal walls, supporting its potential role in improving root canal cleaning efficacy.