Abstract
BACKGROUND: Preparation of severely curved canals presents a challenge owing to the increased likelihood of procedural complications; new generation of nickel-titanium (NiTi) files have shown great promise in the preparation of severely curved canals. The study aimed to compare the effects of WaveOne Gold(WOG), Hyflex EDM (HEDM), and TruNatomy (TRN) NiTi files on the shaping ability (SA) in severely curved root canals. METHODS: Forty-five mandibular molar teeth were divided into three groups (n = 15) based on the instrumentation system employed: TRN, WOG, and HEDM. The teeth were scanned before and after root canal preparation (RCP) via micro-computed tomography (micro-CT) for analyzing the apical transportation (AT) and centering ability (CA) at 1,2,3,4,5,6, and 7 mm from the apex. Statistical analyses were performed using the Kruskal-Wallis test and Bonferroni Dunn's multiple comparison test. RESULTS: Statistically significant differences were observed at 1, 2, 6, and 7-mm (p < 0.05) for AT; no significant differences were observed at 3, 4, and 5-mm in the mesio-distal (MD) direction (p > 0.05). A significant difference was observed at 4 mm for AT in the bucco-lingual (BL) direction (p < 0.05). Significant differences in the CA were observed at 1 and 2-mm in the MD direction and at 4-mm in the BL direction (p < 0.05). CONCLUSIONS: HEDM files contributed to lesser AT and better CA than WOG at 1-mm and lesser AT and better CA than both the TRN and WOG files at 2-mm. TRN files contributed to lesser transportation than HEDM files at 6-mm and lesser transportation than WOG files at 7-mm. Despite the presence of statistically significant differences, none of the tested NiTi systems exceeded the critical canal transportation level (0.3 mm). Within the limitations of this in-vitro study, it can be concluded that all the evaluated NiTi systems in this study can be used in severely curved canals without the risk of any complication pertaining to shaping procedures that may affect the clinical prognosis.