Assessment of dentinal microcrack formation following root canal preparation with rotary, reciprocating and heat-treated NiTi files using micro-CT analysis.

Dentinal microcrack formation during root canal preparation is a critical concern as it predisposes to vertical root fracture and treatment failure. Therefore, it is of interest to evaluate microcrack formation after instrumentation with three nickel-titanium systems (ProTaper Gold, WaveOne Gold and HyFlex EDM) using high-resolution micro-computed tomography. Hence, sixty human mandibular premolars (n=20 per group) were scanned pre-and post-instrumentation and microcracks were assessed for number, length and depth by blinded examiners. WaveOne Gold showed the highest microcrack formation, ProTaper Gold demonstrated intermediate values and HyFlex EDM exhibited the least dentinal damage, with statistically significant differences among groups (p<0.05). Heat-treated NiTi instruments produced fewer microcracks, indicating that file design and kinematics significantly influence dentinal integrity during root canal preparation.