Comparison of Apical Transportation, Centering Ability and Cyclic Fatigue Resistance of Four Rotary File Systems

Aim: The aim of this study was to evaluate the apical transportation, centering ability and cyclic fatigue resistance of Hero shaper, Twisted file, Hyflex file and RACE rotary file systems. Methods: Mesiobuccal ischolar_mains of eighty maxillary molars were divided into four groups and instrumented with Hero shaper, Twisted file, Hyflex file and RACE rotary file systems with a final apical size being 25/.04. Apical deviation was assessed by the radiographic platform method that enables obtaining superimposed images of the first and last instrument used in ischolar_main canal preparation in the same radiograph. Apical transportation was measured in millimeters with the aid of theAUTOCAD2008 software. Forty canals were sectioned at 7mm from the apex and stereomicroscopic Images were taken at 6x magnification before and after instrumentation for evaluation of centering ability. The cyclic fatigue testing was conducted with the instrument rotating freely at angles of curvature of 45 degree. Total 10 instruments were tested in each group. The instruments were rotated at 400 rpm using the X-smart motor (Dentsply, Maillefer) until fracture occurred. Results: There was no statistically significant difference between the four groups in apical transportation and centering ability whereas twisted files showed the maximum cyclic fatigue resistance. Conclusion: The different rotary file systems provided minimum canal transportation and the twisted file performed significantly better in terms of cyclic fatigue resistance.