Comparative evaluation of shaping ability of two nickel-titanium rotary systems using cone beam computed tomography

Background: We evaluated and compared the effects of different NiTi rotary systems - ProTaper Next and New One Shape - on the volume of dentin removed, canal transportation, and canal curvature in extracted human teeth using CBCT scanning with different voxel sizes. Methods: Fifty extracted human maxillary first molars with mesiobuccal canal curvature (25-35 degrees) were used. Specimens were instrumented with the ProTaper Next or New One Shape. Pre- and post-instrumentation scans were performed to compare transportation at the levels of 2, 5, and 8 mm and volumes with two different voxel sizes (0.125-and0.100-mm(3)) using 3D CBCT images. This study evaluated and compare the volume of dentin removed, canal transportation, and canal curvature. Differences according to instrumentation and voxel sizes were assessed using the Mann-Whitney U-test and the Wilcoxon signed-rank test. Results: Significant differences were found between apical and coronal levels for both systems (p < 0.05) in canal transportation. In comparing the systems, similar values were found at each level, without significant difference (p > 0.05) in terms of canal curvature and volume. Voxel sizes did not affect the measurements on canal volume, curvature or transportation; no significant difference was found between the 0.100- and 0.125-mm(3) voxel sizes ( p > 0.05). Conclusions: Both instrumentation systems produced similar canal transportation and volume changes. The two voxel resolutions also showed similar results, however a 0.125-mm(3) voxel size can be recommend for a flat panel CBCT scanner with lower exposure dose.