Correlation between different vertical facial patterns and mandibular incisor alveolar bone loss in patients with skeletal class III malocclusion during pre-surgical orthodontic decompensation.

OBJECTIVES: Pre-surgical orthodontic decompensation (POD) for patients with skeletal Class III malocclusion may lead to alveolar bone loss. This study investigates the relationship between vertical facial patterns and mandibular incisor alveolar bone loss during POD. MATERIALS AND METHODS: A retrospective cohort study was conducted with skeletal Class III patients from the Hospital of Stomatology at Wuhan University. Measurements were taken using cephalometric tomography and cone-beam computed tomography (CBCT) scans. Based on the Frankfort mandibular plane angle (FMA), patients were categorized into high-angle (FMA > 32°), medium-angle (male FMA: 21°-32°, female FMA: 22°-32°), and low-angle groups (male FMA < 21°, female FMA < 22°). The primary outcome was the change in average alveolar bone thickness (ABA%), while secondary outcomes included horizontal thickness at apex and midroot levels and vertical bone level. Data were analyzed using ANOVA and Pearson correlation tests. RESULTS: The study included 95 patients (43 males and 52 females, aged 20.3 ± 2.8 years, POD duration 25.7 ± 13.7 months). High-angle patients had thinnest lingual alveolar bone thickness before POD, experienced greater ABA% loss during POD and had least labial ABA% after POD. Less ABA% before POD was correlated with more ABA% loss during POD. CONCLUSIONS: In skeletal Class III patients with different vertical patterns, high-angle patients are more susceptible to labial alveolar bone loss during POD, which should be considered in clinical planning.