Evaluation of Root Canal Transportation using Bio Race and K -Flexo file instruments: using cone-Bean Computed

Background & Aim: Deviation from the original shape of the canal leads to poor filling and lack of proper canal seal and consequently to the failure of root treatment The aim of this experimental study was to determine the extent of apical transportation after instrumentation with hand K-Flexofile and BioRace rotary instruments by cone-beam computed tomography (CBCT). Material and Methods: In this experimental ex-vivo study Fifty-four extracted maxillary first molars with 19-22 mm length and 5-25 degrees of curvature were selected. The mesiobuccal canals were prepared using either the K Flexo file and Bio Race rotary files. To compare apical transportation, CBCT images were taken before and after canal preparation. The apical transportation values were analyzed using the SPSS software 18  and T-Test, Mann-Whitney ,X2. Results: the mean canal transportation in 1 mm from the apical foramen with Bio Race are more than K Flexo file (P = 0.000).  And the mean canal transportation in 3 mm from the apical foramen with K Flexo file are more than Bio Race (P= 0.047). The Bio Race and K Flexo file  at 2mm from the apical foramen were not significantly different in causing transportation (P= 0.899) Conclusion: Root canal transportation can be seen in all techniques, regardless of the file type used. Although both rotary and manual systems in this study showed some apical transportation, But they both had the same ability to maintain the centrality and curvature of the root canal.