cone-beam computed tomography comparison of canal transportation after preparation with biorace and mtwo rotary instruments and hand k-flexofiles

introduction: the aim of this in vitro study was to evaluate the transportation of mesiobuccal canals of mandibular first molars prepared with either biorace or mtwo rotary instruments or hand k-flexofile, by means of cone-beam computed tomography (cbct). methods and materials: forty-five mandibular molars were selected and randomly divided into three groups ( n =15). mesiobuccal roots of these teeth were prepared by biorace, mtwo, or hand k-flexofile. transportation was measured by pre- and post-operative cbct images. two-way anova analysis was applied to detect any differences between the groups followed by the post hoc tukey’s tests. the level of significance was set at 0.05. results: the non-parametric friedman test was used to compare the behavior of each file at 3-, 6- and 9-mm levels. there were no significant differences between different levels in mtwo group ( p =0.15); however, the differences in k-flexofile and biorace groups were significant ( p >0.05). post hoc tukey’s test revealed significant differences between biorace and k-flexofile and also between mtwo and k-flexofile, both in the 3-mm depths ( p <0.05). conclusion: under the limitations of the present study, biorace and mtwo rotary instruments are considered suitable for canal preparation to greater apical sizes provided that the recommended sequences are observed.