Efficacy Of Incisor Movement With Clear Aligners: A Cone-Beam Computed Tomographic Study

Objective: To evaluate the efficacy of incisor movement with clear aligners by reconstructing virtual root using CBCT(Cone beam computed tomography).Materials and Methods: Pre-and post-treatment CBCT were collected from thirty-four adults who complete the sequence treatment with Invisalign alone.Mimics and other softwares were used to reconstruct the virtual root and match the pre-treatment,post-treatment and virtual images of the incisor.According to the relationship between the center of rotation and the center of resistance,incisors which were designed for uncontrolled tipping,controlled tipping,translation and torque movement were selected.The efficacy of incisor movement was calculated by measuring the area of the roots in the sagittal direction.The statistical analyses were performed using Kruskal-Wallis and Shapiro-Wilk test,?=0.05.Results: A total of 99 incisors were measured.The average efficacy of incisor movement was 57.24%.The efficacy from high to low was uncontrolled tipping(79.16%),controlled tipping(66.85%),translation(45.78%)and torque(36.86%).The efficacy of uncontrolled tipping movement is significantly higher than that of other movement,and there is no significant difference between the efficiencies of translation and torque movement.Overall,the efficacy of labial root movement(69.57%)was significantly higher than lingual root movement(46.98%),and the efficacy of mandibular roots labial movement was significantly higher than that of maxillary roots.Conclusion: The efficacy of incisor movement using Invisalign aligner varies with different types of movement,and the root is more likely to move labially.It remains to be further investigated about the clear aligners,thus facilitating to design a reasonable type and amount of tooth movement for more satisfactory orthodontic outcome.