Objective: To develop a new alveolar bone morphology classification for maxillary incisors in patients with maxillary protrusion, and to investigate the association of alveolar morphology with skeletal patterns and alveolar bone defects following retraction.
Methods: A retrospective study of CBCT scans was performed for 250 patients with maxillary protrusion. The morphology of alveolar bone around maxillary incisors was classified into four types: A1 (upright maxillary incisor in thin alveolar bone), A2 (lingually inclined maxillary incisor in thin alveolar bone), B1 (upright maxillary incisor in thick alveolar bone) and B2 (lingually inclined maxillary incisor in thick alveolar bone). The association of alveolar types with different skeletal patterns and the incidence of post-treatment alveolar bone defects were analysed.
Results: For maxillary incisors in patients with maxillary protrusion, A1 was the most common alveolar type (33.4%), followed by A2 (28.5%), B1 (22.1%) and B2 (16.0%). Types B1 (34.4%) and A2 (42.2%) were the most common in maxillary central and lateral incisors, respectively. In high angle patients, A2 and A1 were the most common types for maxillary lateral (49.6%) and central incisors (41.2%), respectively. Additionally, types A1 and A2 were at greater risk of severe lingual dehiscence.
Conclusion: This is the first alveolar bone morphology classification for maxillary incisors in patients with maxillary protrusion. The alveolar types exhibited a significant association with skeletal patterns and the incidence of alveolar bone defects after retraction.