Abstract
CONTEXT: Shaping, in curved canals, is challenging due to tendency of instruments to alter curvature, resulting in procedural errors. The ability of shaping an instrument can be evaluated with variables such as transportation of canal and centering ratio (CR). Manufacturers constantly introduce newer Ni-Ti rotary instruments with optimized properties, due to which clinicians constantly need to evaluate, to be able to select better systems. AIM: The aim of this study was to compare and evaluate CR and canal transportation (CT) after instrumentation of curved canals with TruNatomy (TRN), twisted file (TF), and one curve (OC) systems using cone-beam computed tomography (CBCT). MATERIALS AND METHODS: Fifty-one freshly extracted mandibular molars with curved mesiobuccal canals were selected and arbitrarily allocated into three groups - TRN, OC, and TF. Their CBCT scans prior to as well as after the canal instrumentation were recorded at three cross-sectional axial levels - 2 mm, 5 mm, and 8 mm from apical exit to determine and compare CT and CR by measurements taken from distal and mesial directions. STATISTICAL ANALYSIS USED: Data were compared and analyzed statistically with the help of one-way analysis of variance along with by post hoc analysis. RESULTS: All three groups performed similarly, with no statistical difference with regard to transportation of canal along with centering ability (P > 0.005). TRN showed the least CT at three cross-sectional levels. For CR, TRN performed better at 2 mm, whereas OC centered better at 5 mm and 8 mm from the apex. Results, however, were nonsignificant. CONCLUSIONS: All file systems were able to maintain and conserve the original anatomical curvature of the root canal along with minimal transportation and were able to remain centered while preparing curved canals.