Influence of contemporary nickel–titanium rotary systems on root canal dentin preservation: A cone-beam computed tomography-based in vitro study

Context: Preservation of canal dentin during rotary root canal instrumentation is essential to maintain structural tooth strength and prevent procedural mishaps. Limited data exist comparing dentin changes between contemporary nickel–titanium (NiTi) rotary systems using three-dimensional imaging. Aims: This study aims to evaluate and compare canal dentin changes following instrumentation with three NiTi rotary file systems using cone-beam computed tomography (CBCT). Materials and Methods: Sixty-six extracted human mandibular premolars with single straight canals were decoronated and randomly allocated to three groups ( n = 22) based on the rotary system used: ProTaper Gold, NeoEndo Flex, and GenEndo. Canals were prepared according to the manufacturer’s protocols. Pre- and post-instrumentation CBCT scans were obtained. Dentin thickness was measured at 3 mm, 6 mm, and 9 mm from the apex. Differences in dentin thickness pre- and post-instrumentation were calculated for each system. Statistical Analysis Used: One-way analysis of variance followed by Tukey’s post hoc test was performed; statistical significance was set at P < 0.05. Results: Significant intergroup differences in dentin reduction were observed at all root levels ( P < 0.001). Mean reduction (coronal–apical) was highest with ProTaper Gold (1.15–0.97 mm), intermediate with NeoEndo Flex (0.56–0.51 mm), and lowest with GenEndo (0.28–0.10 mm). Conclusions: Different NiTi rotary systems result in varying canal dentin changes. Among those evaluated, GenEndo preserved dentin most effectively, while ProTaper Gold resulted in greater dentin reduction. CBCT is a reliable tool for non-destructive assessment of dentin changes after instrumentation.