Objectives: The aim of our study was to compare the centering ability of two recently introduced NITI file systems-New One Shape™ and Protaper Next™. Methods: 40 teeth were divided into 2 groups of 20 teeth each. A gig with radiopaque markers was prepared for each tooth, and an X ray was taken with a #10 file to the working length in the canal. Each group prepared using one of the file systems in accordance to manufacturer’s instructions. The last rotary instrument to be used was X rayed in the canal using the gig. Both X ray imaged were digitized. A point was drawn at the tip of each file, and images were superimposed and aligned using the radiopaqe markers imbedded in the gig. The distance between the marked points drawn earlier was measured. Results: No significant difference was found between the file systems. The mean deflection for One Shape and Protaper Next was 51.38 and 46.72 respectively. Mean deflection for single rooted teeth was 55.95 and 44.68 for multi-rooted teeth. The mean deflection was lowest in multi rooted teeth while using Protaper Next, (35.93) however this was not statistically significant. Conclusions: Within the parameters of this study, it could be concluded that no statistically significant difference in centering ability exists between New One Shape™ and Protaper Next™ systems in medium curved canals.
