Comparative study of root canal mechanical preparation with two systems with different kinematics. Ex vivo micro-CT study

INTRODUCTION: Oval and ribbed root canals present a major challenge in endodontic treatment due to their complex anatomy, which fosters the accumulation of debris and bacteria. Mechanical preparation systems have been developed to improve shaping efficiency and canal centricity in these anatomically complex canals. AIM: To compare, using micro-computed tomography, pulp space volume increase, untouched canal surface area, and apical transportation in oval root canals prepared with WaveOne Gold (WOG) or XP-endo Shaper (XPS). MATERIALS AND METHOD: 30 extracted single-rooted upper second premolars with oval root canals were randomly divided into two experimental groups and instrumented with WOG (n: 15) or XPS (n: 15). All specimens were scanned with micro-CT (SkyScan 1272; Bruker-microCT) for comparison before and after instrumentation using the following acquisition parameters: 19µm voxel, 30 kV, 800 mA, 0.6° rotation step, 360° rotation and 1 mm thick aluminum filter. Initial and final volumes, surface areas and centricities were analyzed to calculate pulp space volume increase, untouched surface area and transportation. Data were analyzed using paired Student's t-tests, Wilcoxon signed ranks or Mann-Whitney U tests, as appropriate (p < 0.05 significant). RESULTS: There was no significant difference between WOG and XPS in pulp space volume increase (p=0.26) or untouched surface area (p>0.99). However, there were significant differences in centricity on the X and Y axes (p<0.05), while on the Z axis, the differences were not significant (p=0.05). CONCLUSION: WOG and XPS had similar shaping effectiveness. All files were able to clean and shape moderately curved canals with minimal apical transportation.