Abstract: Objective: To explore the incidence rates of fenestration and dehiscence, and the bone remodeling characteristics of the anterior alveolar bone before and after orthodontic treatment of hyperdivergent skeletal Class Ⅱ malocclusion by cone beam computed tomography (CBCT). Methods: Forty-six cases with hyperdivergent skeletal Class Ⅱ malocclusion were selected [male: 18 cases, female: 28 cases, age: (16.9±2.2) years]. The alveolar bone of the incisors of both jaws were measured to calculate the incidence rates of fenestration and dehiscence, and the morphological characteristics of the alveolar bone before and after orthodontic treatment. Results: The comparison of fenestration incidence before and after treatment revealed a statistically significant reduction, with rates of 6.39% prior to treatment and 3.00% following treatment (P<0.05). Conversely, the incidence of dehiscence remained relatively stable, with pre-treatment and post-treatment rates of 22.55% and 23.91%, respectively, exhibiting no statistically significant difference (P>0.05).Notably, post-treatment evaluations indicated a statistically significant increase in the depth of lingual and palatal dehiscence defects, accompanied by a significant decrease in the thickness and area of alveolar bone (P<0.05). Conclusion: Orthodontic treatment in patients with hyperdivergent skeletal Class Ⅱ malocclusion has led to the restoration of labial bone defects in both the upper and lower incisors, resulting in a reduced incidence rate of fenestration and dehiscence. However, it is noteworthy that the lingual and palatal sides of the alveolar bone experience a reduction in bone thickness and area, along with an increase in dehiscence.

Key words: hyperdivergent skeletal Class Ⅱ malocclusion, orthodontic treatment, fenestration, dehiscence