Assessment of buccal and lingual alveolar bone thickness and buccolingual inclination of maxillary posterior teeth in patients with severe skeletal Class III malocclusion with mandibular asymmetry

Introduction: The purpose of this study was to evaluate the buccal and lingual alveolar bone thickness and buccolingual inclination of maxillary posterior teeth in patients with severe skeletal Class III malocclusion with and without mandibular asymmetry and compare with those in patients with skeletal Class I malocclusion. Methods: Cone-beam computed tomography images of 69 patients with severe skeletal Class III malocclusion and 30 patients with skeletal Class I malocclusion were collected and reconstructed with Dolphin 3D software. Based on the distance from menton to the sagittal plane (d), the patients with skeletal Class III malocclusion were divided into a symmetry group (d <= 2 mm) and an asymmetry group (d >= 4 mm). Buccal and lingual alveolar bone thickness and buccolingual inclination of maxillary posterior teeth were measured and compared. Correlations among dental measurements, severity of sagittal discrepancy, and mandibular deviation were analyzed. Results: Maxillary posterior teeth on the deviated side in Class III asymmetry group and symmetry group were buccally inclined compared with the Class I group (P < 0.001). A significant negative correlation was noted between buccolingual inclination of maxillary posterior teeth and ANB value with Spearman correlation coefficient of maxillary first molar, second premolar, and first premolar of -0.687, -0.485 and -0.506, respectively (P < 0.001). Maxillary first molar showed thinner buccal alveolar bone on deviated side in asymmetry group and symmetry group of Class III, compared with the Class I group, with average values of 1.21 mm, 1.19 mm, and 1.83 mm, respectively (P < 0.05). The maxillary first premolar also showed thinner buccal alveolar bone on deviated side in Class III asymmetry group compared with the Class I group, with average values of 0.87 mm and 1.28 mm, respectively (P < 0.05). Conclusions: Decompensation of buccally inclined posterior teeth in patients with skeletal Class III malocclusion should be more cautious owing to thinner buccal alveolar bone to avoid a high risk of fenestration and dehiscence.