Abstract
Aim: To evaluate, using micro-computed tomography, the root canal transportation and centering ability of BioRaCe and AlphaKite rotary instruments, and their ability to eradicate canal variations after preparation of the mesiobuccal root of the first maxillary molar tooth.
Methodology: Mesiobuccal roots of 20 maxillary first molars with similar angles of curvature were divided randomly into two groups and scanned using a SkyScan 1172 micro-CT scanner (SkyScan N.V., Aartselaar, Belgium). Root canals were then prepared with BioRaCe (FKG Dentaire, La Chaux-de-Fonds, Switzerland) or AlphaKite (Komet, Lemgo, Germany) instruments. The prepared roots were re-scanned and cross-sectional images of the pre- and post-instrumentation scans were reconstructed using the SkyScan reconstruction software. The amount of transportation was assessed quantitatively using the cross-sectional images by measuring the shortest distance from the edge of the uninstrumented canal to the periphery of the root (mesial and distal) and then comparing this with the same measurements obtained from the instrumented images. A negative result indicates transportation toward the distal surface of the root (inner curvature), a positive result toward the mesial surface (outer curvature), and nil, the absence of transportation. The centering ratio was calculated by using a formula in which a result of ‘1’ indicates perfect centering. Student t-tests and ANOVA tests were used for statistical analysis. Three- dimensional images of the root canals were then reconstructed using the appropriate software (Amira 4.1; Visage Imaging Inc., USA), to evaluate eradication of canal variations by the two instruments.
Results: The average canal transportation with BioRaCe instruments at the coronal, middle and apical thirds were, -0.12 ± 0.19, -0.01 ± 0.09 and +0.06 ± 0.05 mm, respectively, with a significant difference (P < 0.05) in the amount of transportation between the coronal and apical levels. The average canal transportation with AlphaKite instruments in the coronal, middle and apical thirds were -0.05 ± 0.22, ₋0.04 ± 0.10 and +0.03 ± 0.03 mm, respectively, with no significant difference between the levels (P > 0.05). Centering ratio using BioRaCe at the coronal (0.32 ± 0.25), middle (0.53 ± 0.23), and apical (0.57 ± 0.27) thirds showed no significant difference between the levels (P > 0.05). For the AlphaKite system, the centering ratio results were (0.46 ± 0.31) for the coronal, (0.56 ± 0.29) for the middle and (0.66 ± 0.24) for the apical thirds. No significant difference was found between the levels (P > 0.05). There was no statistically significant difference between the systems in regard to canal transportation and their centering ability across all levels (P > 0.05). Neither was able to completely eradicate canal variations of the mesiobuccal root of maxillary first molars.
Conclusions: Within the limitations of this ex vivo study, the two new nickel-titanium instruments produced moderately well centered canals with minimal canal transportation. The complex anatomy of the mesiobuccal root of maxillary first molars was confirmed.