Comparative Evaluation of Dentinal Microcrack Using M3 ProGold, Mtwo Rotary File and Hand File in Root Canal Therapy: An In-Vitro Study

Background: Vertical root fractures (VRFs) can occur during root canal therapy, either during canal preparation or obturation, and can ultimately lead to tooth loss. Rotary systems are recognized for their common use, user-friendliness, and low incidence of root canal preparation accidents. Objectives: This study aimed to evaluate the surface defects in root canal dentine following preparation with two different common nickel-titanium (NiTi) rotary files compared to a traditional hand k-file. Methods: In this experimental study, 100 single-canal mandibular premolars were selected and divided into four groups. Group 1 samples were unprepared. Group 2, group 3, and group 4 samples were prepared using hand K-files, the Mtwo rotary system, and the M3 ProGold rotary system, respectively. All root canals were irrigated with 10 mL of 2% NaOCl solution, followed by a final rinse with normal saline. After preparation, the samples were sectioned at 3, 6, and 9 mm distances from the apex and evaluated under 12x magnification with a stereomicroscope. The defects were categorized as no defects, fractured, and defective. Data were analyzed using SPSS 25 with a P < 0.05 significance level. Results: Group 3 exhibited the most significant defects, while the control group had the fewest. A two-way ANOVA indicated significant interactions between preparation methods and section levels (P = 0.012). Tukey’s post hoc test confirmed that group 3 had significantly more defects than groups 2 and 4 (P < 0.05). Conclusions: The M3 ProGold rotary file system creates fewer dentinal microcracks compared to the Mtwo rotary file system and hand K-files. Therefore, the M3 ProGold system may be a better choice for root canal therapy.