Three-dimensional analysis of mandibular functional units in adult patients with unilateral posterior crossbite: A cone beam study with the use of mirroring and surface-to-surface matching techniques

Objectives: To use three-dimensional (3D) mirroring and surface-to-surface techniques to determine any differences in mandibular functional unit shape and morphology between the crossbite side and non-crossbite side in adult patients with posterior unilateral crossbite who had not received any corrective treatment for malocclusion. Materials and Methods: Cone-beam computed tomography (CBCT) records from 24 consecutive adult white patients (mean age, 27.5 years; range 22.6-39.7 years; 14 women and 10 men) seeking treatment for maxillary transverse deficiency were assessed in this study. The control group comprised CBCT scans from age-and sex-matched patients. Segmentation masks were generated to obtain 3D surface mesh models of the mandibles and analyze the six skeletal functional units, which were further analyzed with reverse engineering software. Results: Statistically significant differences in the mean surface distance when comparing the study sample and the control sample were found at the condylar process, mandibular ramus, angular process (P <=.0001), and alveolar process (P <=.01); no statistically significant differences were found for the coronoid process, the chin, and the mandibular body (P >=.5). Conclusions: The condylar, angular, and alveolar processes plus the mandibular ramus appear to play a more dominant role than did the body, the coronoid, and the chin units in the asymmetry of the mandible in patients with unilateral crossbite.