Microcomputed tomographic evaluation of shaping ability of two thermo mechanically treated single-file systems in severely curved roots

CONTEXT: Canal shaping abilities such as canal transportation, centering ability, and preparation time are important and have to be considered before using any Nickel–Titanium file system. AIM: This in vitro study aimed to evaluate and compare the amount of canal transportation, centering ability, and time required for the shaping of severely curved canals with WaveOne Gold (WOG) Primary Reciprocating file and One Curve (OC) Rotary file using the micro computed tomography (μCT). MATERIALS AND METHODS: Thirty intact mesial roots of extracted human mandibular first molars having severe curvature (25°–35°) were selected. Samples were divided into two groups. Samples in Group I and II were shaped with WOG primary reciprocating files and OC rotary files, respectively, to the working length. Time required to prepare each canal was recorded. μCT pre- and post-instrumentation scans of all samples were taken. The cross-sectional images at 3, 6, and 9 mm from the radiographic apex were selected for analysis. Statistical analysis was performed using the Kruskal–Wallis and unpaired t-test. RESULTS: At 3 mm, OC showed statistically lower canal transportation with mean value (0.17 ± 0.10) than WOG (0.55 ± 0.42). Furthermore, OC showed statistically significant better centering ability (0.59 ± 0.25) than WOG (0.39 ± 0.20) at 3 mm level. However, the differences between both instruments were not statistical significant at 6 and 9 mm level for canal transportation and centering ratio. WOG reciprocating file required less time for canal preparation than OC file. CONCLUSIONS: OC rotary file showed less canal transportation and better canal centring ability than WOG file, during the preparation of severely curved canals. However, WOG required less time for canal preparation.