Abstract：
Low-angle skeletal class II malocclusions are often observed with sagittal and vertical developmental abnormalities of the mandible. Two-phase orthodontic treatment of functional orthopedic therapy combined with fixed correction is one of the most common methods to treat of skeletal class II malocclusions. This case report describes the two-phase orthodontic treatment of a patient with severe low-angle skeletal class II malocclusion. A Twin Block orthodontic appliance was used to improve mandibular growth, and the adjustment of the occlusal relationship using a fixed appliance after functional therapy. After treatment, a significant improvement was observed in the patient\'s facial appearance and occlusal relationship. Additionally, a 7-year follow-up confirmed the stability of the treatment results. Although a vertical facial growth direction is difficult to control, the Twin Block orthodontic appliance in adolescents might effectively improve the difference in the sagittal growth of the mandible. Whilst the growth pattern could not be fully controlled, the treatment significantly improved the patient\'s facial profile and occlusion.
摘要：
经常观察到低角度骨骼II类咬合不正，下颌骨矢状和垂直发育异常。功能性矫形结合固定矫正的两阶段正畸治疗是治疗骨骼II类错牙合的最常用方法之一。此病例报告描述了严重的低角度骨骼II类错牙合患者的两阶段正畸治疗。双块正畸矫治器用于改善下颌骨生长，以及功能治疗后使用固定矫治器调整咬合关系。治疗后,观察到患者的面部外观和咬合关系有显著改善。此外,7年的随访证实了治疗结果的稳定性.虽然面部的垂直生长方向很难控制，在青少年中使用TwinBlock正畸矫治器可以有效改善下颌骨矢状生长的差异。虽然生长模式无法完全控制，治疗显著改善了患者的面部轮廓和咬合。
