Comparative evaluation of microcrack formation and fracture resistance of root dentin with the use of three different rotary files: An in vitro study

Background: Successful endodontic treatment requires thorough cleaning, shaping, and obturation of the root canal. Introduction of nickel–titanium rotary files has improved canal shaping; however, their effect on root dentin can differ and influence the long-term success. Aim: This study evaluates and compares the incidence of microcracks and the fracture resistance of root dentin after instrumentation with ProTaper Gold (PTG), XP-endo Shaper (XPS), and TruNatomy (TRN) rotary file systems. Materials and Methods: A total of one hundred and twenty single-rooted mandibular premolars were divided into two groups: microcrack evaluation ( n = 60) and fracture resistance testing ( n = 60). The teeth were instrumented using PTG, XPS, or TRN files following standard protocols. Microcracks were assessed using a scanning electron microscope, and fracture resistance was assessed by universal testing machine. Statistical Analysis: Chi-square and ANOVA tests were used for microcrack and fracture resistance analysis, with a significance level of 0.05. Results: PTG showed the highest microcrack incidence, especially in the middle third, while TRN and XPS exhibited fewer cracks. PTG specimens had the lowest fracture resistance. Conclusion: PTG instrumented specimens caused the most microcracks and lowest fracture resistance. XPS and TRN were concluded to be more conservative, improving fracture resistance.