Assessment of canal centering ability and topography of three nickel- titanium rotary systems

Resumo

Objective: This study aimed to evaluate the canal centering ability and topography of BioRaCeTM (BR), Wizard CD PlusTM (WP), and Wizard NavigatorTM (WN) instruments. Materials and method: mesiobuccal roots of upper first molars were selected and randomly distributed in three groups (n=10), according to the rotary system used for instrumentation. Canal transportation was assessed at 2, 4, 6, and 8 mm from the root apex, by subtracting cone bean computed tomography (CBCT) images taken before and after preparation. The root canal center was marked in pre- and post-preparation images, and the distance between these points was measured in bucco-palatal (BP) and mesio-distal (MD) directions. New instruments were analyzed under scanning electron microscopy (SEM) regarding their surface finishing, topographical features, and surface defects. The SEM images were obtained at the tip of the instrument, and at 5 mm from the tip. Data of the canal centering ability were analyzed by two-way ANOVA (α = 0.05). Results: regardless of root level (2, 4, 6, and 8 mm), all groups presented canal transportation in both directions. Significant differences were not detected (p > 0.05). Surface finishing was regular in the BR group with rounded transitional angle. Cutting edges had a sharp angle in BR and WN groups, while WP instruments had a flattened angle. Conclusion: despite such topographical differences between the rotary instru- ments tested, none of them were able to exactly maintain the original root canal center, and no significant differences were observed among groups. Keywords: Root canal preparation. Endodontics. Scanning electronic microscopy. Rotary instruments.