BACKGROUND: Root canal shaping without any procedural error is of the utmost preference. Therefore, the purpose of this study was to use micro-computed tomography to evaluate and compare the root canal shaping efficacy of ProTaper rotary files and standard stainless steel K-files.

MATERIAL AND METHODS: Sixty extracted upper second premolars were selected and were divided into 2 groups of 30. Before preparation, all samples were scanned by micro-CT. Then, 30 teeth were prepared with stainless steel files and the remaining 30 with ProTaper rotary files. Canal transportation and centering ability before and after root canal shaping were assessed using micro-CT. The amount and direction of canal transportation and the centering ratio of each instrument were determined in the coronal, middle, and apical parts of the canal. The 2 groups were statistically compared using one-way ANOVA.

RESULTS: ProTaper rotary files gave less transportation (p<0.001) and better centering ability (p<0.00001) compared with stainless steel files.

CONCLUSIONS: The manual technique for preparation of root canals with stainless steel files produces more canal transportation, whereas rotary files remain more centered in the canal.

Keywords: X-Ray Microtomography - methods, Stainless Steel, Root Canal Preparation - methods, Dental Pulp Cavity - surgery, Dental Instruments, Analysis of Variance