Abstract: Objective: To evaluate the periodontal tissue and alveolar width changes of lower anterior teeth before and after modified corticotomy, and to assess the surgical safety and provide reference for clinic practice. Methods: Healthy adult cases with moderate Angle Class Ⅲ malocclusion were undergone orthodontic treatment combined with modified corticotomy. The various periodontal index and alveolar width of lower anterior teeth before and after orthodontic treatment were measured and compared with each other. Results: Probing depth, bleeding index and index of gingival atrophy before and after treatment showed no statistical difference. Keratosic gingival after orthodontic treatment(5.8±2.4 mm)was thicker than pre-treatment (5.2±1.9 mm) (P=0.041). Alveolar bone at the apex area after treatment(6.04 ± 4.57 mm) was thicker than pre-treatment(5.32±3.87 mm) (P=0.024 ). Labial alveolar bone at the apex area after treatment(2.27±1.72 mm)was thinner than pre-treatment(2.88±2.35 mm ) (P=0.014 ). Lingual alveolar thickness at the apex area after treatment(3.97±3.49 mm )was thicker than pre-treatment (2.54±2.06 mm) (P=0.040). Thickness of mandible at B point after treatment(7.17±5.21 mm)was thicker than pre-treatment(6.47±3.99 mm) (P=0.042 ). Conclusion: It is safe to treat moderate Angle Class Ⅲ malocclusion by orthodontic treatment combined with modified corticotomy, which could even stimulate the alveolar proliferation of lower anterior teeth.

Key words: Angle Class Ⅲ, Periodontal tissue, Corticotomy, Safety