目的：应用锥形束CT (cone-beam computed tomography, CBCT)评价治疗前双颌前突患者前牙区牙槽骨缺损情况。方法：选取50名未经正畸治疗的患者，根据年龄分为成人组［30例，平均（22.9±4.2）岁］与青少年组［20例，平均（13.1±1.0）岁］，其中成人组根据垂直骨面型分为低角组（9例）、均角组（11例）与高角组（10例），所有患者在相同参数条件下进行CBCT扫描，在其CBCT图像上诊断牙槽骨开窗与开裂的情况并分析其分布特征。结果：双颌前突患者发生牙槽骨缺损的人数比为94.00%。所有接受检验的牙齿牙槽骨缺损发生率为38.60%。牙槽骨缺损绝大多数发生在唇侧（98.66%）；牙槽骨开窗主要发生在上颌，而骨开裂主要发生在下颌。青少年组牙槽骨开裂（3.06%）及骨缺损（30.13%）发生率明显低于成人组的骨开裂（11.73%）及骨缺损（42.46%）发生率，P<0.05；而两组的牙槽骨开窗发生率差异无统计学意义（P>0.05）。低角组骨开窗（22.22%）的发生率低于均角组（33.84%）和高角组（37.50%），P<0.05。牙槽骨缺损发生率最低的牙位为上颌中切牙。结论：双颌前突患者在正畸治疗前即存在广泛的牙槽骨缺损，缺损的发生率受年龄、垂直骨面型等因素影响。

Objective： To investigate the alveolar bone defects of anterior alveolar bone in patients with bimaxillary protrusion by using cone-beam computed tomography (CBCT). Methods: The samples consisted of 50 patients with bimaxillary protrusion, who were assigned to the teenage group［20 cases, （13.1±1.0） years］ and adult group［30 cases, (22.9±4.2) years］ . The adult group included 9 hypo-divergent, 11 normo-divergent and 10 hyperdivergent patients. The images were obtained by using NewTom VG CBCT and the alveolar defects were evaluated. Results: The ratio of the patients had alveolar bone defects was 94.00%. Meanwhile, the defects were associated with 38.60% of all the teeth. Most defects occurred on labial alveolar bone (98.66%); fenestration was found more in the maxillary alveolar region and dehiscence occurred more in the mandible. The dehiscences (3.06%) and defects prevalence (30.13%) of the teenage group were significant lower than those of the adult group (11.73% vs. 42.46%), P<0.05; while there was no significance of the fenestrations prevalence between the two group (P>0.05). The hypo-divergent group had lower fenestrations prevalence (22.22%) than the normo-divergent (33.84%) and hyper-divergent groups (37.50%), P<0.05. The upper central incisor had the lowest alveolar bone defect prevalence. Conclusion: Alveolar bone defects are common findings in patients with bimaxillary protrusion before orthodontic treatment. The prevalence of defects is affected by age and vertical-growth type.