Objectives: To compare dentinal microcrack formation following root canal instrumentation using ProTaper Universal, Blue NiTi EndoArch, and Twisted File Adaptive systems in mesial roots of mandibular molars using micro-computed tomography. Methods: Forty-five extracted mandibular molars with separate mesial canals were decoronated and randomly allocated into three groups based on instrumentation systems. Samples were scanned before and after instrumentation using micro-CT at 14 μm resolution. Pre- and post-instrumentation cross-sections were evaluated for microcrack formation at coronal, middle, and apical thirds by calibrated blinded observers. Statistical analysis was performed using Friedman test and paired comparisons. Results: Significant differences were observed between pre- and post-instrumentation microcrack formation with ProTaper Universal (p = 0.012) and Blue NiTi EndoArch (p = 0.031). Twisted File Adaptive did not demonstrate significant changes (p = 0.067). The middle third exhibited the highest microcrack formation in rotary systems, while adaptive motion instruments showed minimal crack propagation. Conclusions: Rotary instrumentation systems produced significantly higher dentinal microcracks compared to adaptive motion systems. Twisted File Adaptive demonstrated superior dentin preservation under the study conditions.
Bodkhe et al. (Sun,) studied this question.