Assessment of canal centering ability and topography of three nickel-titanium rotary systems / Avaliação da centralização do preparo e da topografia de três sistemas rotatórios de níquel-titânio

ABSTRACT

Objective: This study aimed to evaluate the canal cen-tering ability and topography of BioRaCeTM (BR), Wi-zard CD PlusTM (WP), and Wizard NavigatorTM (WN) instruments. Materials and method: mesiobuccal roots of upper first molars were selected and randomly dis-tributed in three groups (n=10), according to the rota-ry system used for instrumentation. Canal transporta-tion 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-prepa-ration images, and the distance between these points was measured in bucco-palatal (BP) and mesio-distal (MD) directions. New instruments were analyzed un-der 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 (? = 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 instru-ments had a flattened angle. Conclusion: despite such topographical differences between the rotary instru-ments tested, none of them were able to exactly main-tain the original root canal center, and no significant differences were observed among groups.