Critical factors to ensure stable occlusion in Class III patients following surgical-orthodontic treatment

Achieving coordination between maxillary and mandibular arches is critical for establishing stable occlusion. This study evaluated posterior occlusal intercupation and identified predictive factors for normal posterior buccal overjet in skeletal Class III patients following surgical-orthodontic treatment.

A retrospective analysis was conducted on 51 Class III patients (24 males, 27 females) who underwent bimaxillary surgery and orthodontic treatment. Cone-beam computed tomography (CBCT) scans were obtained at three time points: pre-treatment (T0), pre-surgery (T1), and post-treatment (T2). Maxillary transverse discrepancies and buccolingual inclinations of maxillary and mandibular molars were assessed using Amira® 3D Pro software. Patients were categorized according to posterior buccal overjet at T2 into two groups: Group 1 (normal occlusion) and Group 2 (defective occlusion). Intergroup comparisons and logistic regression were conducted to determine predictive factors.

At T0, Group 2 exhibited significantly narrower maxillary arch widths, more maxillary crowding, greater facial divergence, more pronounced maxillary transverse discrepancy (MTD), and increased molar inclinations on the menton non-deviation side compared to Group 1. At T1, molar inclinations were similar between the two groups. At T2, Group 2 continued to exhibit greater facial divergence, a narrower maxillary arch width, and residual MTD. Logistic regression identified the Wits appraisal at T0 and MTD at T1 as significant predictors of post-treatment occlusion.

A logistic regression model incorporating the pre-treatment Wits appraisal and pre-surgical MTD could predict posterior occlusal outcomes after surgical-orthodontic treatment in Class III patients.