Comparative evaluation of dentinal microcrack formation using ProTaper universal, Blue NiTi endoarch, and twisted file adaptive systems: A micro-computed tomographic study

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.