Assessment of linear and angular positions of central incisors in the maxilla and mandible related to planned overbite changes with clear aligner therapy.

INTRODUCTION

The study aimed to determine how the achieved labiolingual movements of central incisors compared with those planned in patients treated with the Invisalign (Align Technology, San Jose, Calif) appliance and requiring differing amounts of overbite correction.

METHODS

Adults treated with Invisalign aligners and satisfying selection criteria were chosen from a large database. Pretreatment, planned, and achieved arch depth/linear changes and angular changes of the maxillary and mandibular central incisors were calculated from relevant stereolithography files within Align Technology's treatment planning Web-based software application via metrology software and illustrated via Bland-Altman plots. Pretreatment, planned, and achieved incisor apices positions were calculated.

RESULTS

A total of 232 patients were evaluated. Achieved arch depth/linear changes did not differ significantly (P ≥0.17) from those planned, whereas all achieved angular changes differed significantly (P ≤0.01) from those planned. The mean accuracy of planned arch depth/linear changes ranged 99.2%-100.5%, and the mean accuracy of planned angular changes ranged 57.0%-90.3%. Bland-Altman plots showed that differences between planned and achieved angular changes increased as planned overbite correction increased. Changes in central incisor apical positions were related to changes in root angulation.

CONCLUSIONS

Although achieved arch depth/linear changes were close to those planned with the Invisalign appliance, angular changes differed significantly from those planned pretreatment. Central incisor root apices moved more labially than planned as planned changes to overbite increased, with a corresponding potential increased risk of alveolar bony dehiscence and fenestration.