RESUMEN
BACKGROUND: Root canals of primary teeth are commonly prepared with endodontic files that are originally manufactured for permanent teeth. AIM: This micro-computed tomography (micro-CT) study evaluated and compared the changes in root canal morphology after preparation with different conventional and rotary files in primary teeth and young permanent teeth. DESIGN: Seventy-two extracted primary and permanent molars were selected and randomly assigned to three subgroups according to the file systems used (n = 12/each). After pre-scanning of teeth with micro-CT, root canals were prepared with One Shape and Revo-S rotary systems and conventional endodontic files. After rescanning procedure, changes in canal volume, surface area, uninstrumented surface area, and apical transportation were evaluated. Mann-Whitney U test, Kruskal-Wallis test, and Conover's multiple comparison test were used for statistical analysis (P = .05). RESULTS: Instrumentation with rotary files resulted in significantly greater volume and surface area of root canals and less uninstrumented areas (P < .001) than with manual files (P < .001). Primary molars showed significantly less apical transportation than permanent teeth (P < .001). CONCLUSIONS: Preparation of canals with rotary files could be a viable alternative to conventional files in primary teeth. Regardless of the file system used, uninstrumented areas still exist in both primary teeth and permanent teeth.