A cone-beam computed tomography study of orthodontic apical root resorption

Background/purposeRoot resorption is an important problem in orthodontic treatment. Basically, the root resorption is evaluated by using two-dimensional images (e.g., periapical films, panoramic films, and cephalometric films). However, the use of such images sometimes underestimates the root resorption due to incorrect projection and magnification. The purpose of this study was to evaluate the correlations between root resorption and the amount of tooth movement during orthodontic treatment using cone-beam computed tomography (CBCT).Materials and methodsWe used CBCT to measure the root resorption and amount of tooth movement around six teeth (bilateral maxillary central incisors, lateral incisors, and canines) in eight patients, before orthodontic treatment and after 7 months of treatment. We then calculated the correlation between root resorption and the amount of tooth movement.ResultsThe root resorption was largest in the lateral incisors (0.39 ± 0.32 and 0.48 ± 0.19 mm in the right and left maxillary lateral incisors, respectively), followed by the central incisors (0.25 ± 0.16 and 0.32 ± 0.34 mm in the right and left maxillary central incisors), and then the canines (0.18 ± 0.19 and 0.19 ± 0.14 mm in the right and left maxillary canines). The average Pearson's correlation coefficient for the association between root resorption and the amount of tooth movement was –0.48.ConclusionResults show that larger tooth movement after orthodontic treatment may be associated with increased severity of root resorption. This study has demonstrated that CBCT is a useful approach for evaluating apical root resorption after orthodontic treatment.