Orthodontic resident, Division of Orthodontics, Department of Orofacial Sciences, University of California-San Francisco, CA, USA.
Am J Orthod Dentofacial Orthop. 2013 Aug;144(2):218-28. doi: 10.1016/j.ajodo.2013.03.018.
Facial convexity related to bimaxillary protrusion is prevalent in many populations. Underlying skeletal protrusion combined with increased dentoalveolar protrusion contributes to facial muscle imbalance and lip incompetence, which is undesirable for many patients. In this study, we evaluated the relationship between soft-tissue and hard-tissue changes in an orthodontically treated Asian population.
Twenty-four consecutive adult Asian patients (mean age, 24 years), diagnosed with severe bimaxillary dentoalveolar protrusion, were evaluated using pretreatment and posttreatment cone-beam computed tomography. The patients were treated with 4 first premolar extractions followed by anterior retraction with either skeletal or intraoral anchorage. Serial cone-beam computed tomography radiographs were registered on the entire cranial base and fossa. Soft-tissue and hard-tissue changes were determined through landmark displacement and color mapping.
Upper lip retraction was concentrated between the nasolabial folds and commissures. Lower lip retraction was accompanied by significant redistribution of soft tissues at pogonion. Soft-tissue changes correlated well with regional facial muscle activity. Significant retractions (2-4 mm) of the soft tissues occurred beyond the midsagittal region. Use of skeletal anchorage resulted in 1.5 mm greater lower lip retraction than intraoral anchorage, with greater retraction of the maxillary and mandibular incisor root apices.
Profound soft-tissue changes accompanied retraction of the anterior dentition with both treatment modalities.
与双颌前突相关的面凸度在许多人群中较为常见。骨骼突出与牙牙槽突突出的共同作用导致面部肌肉失衡和唇闭合不全，这对许多患者来说是不理想的。在这项研究中，我们评估了正畸治疗的亚洲人群中软组织和硬组织变化之间的关系。
连续 24 例成人亚洲患者（平均年龄 24 岁），患有严重的双颌牙牙槽突前突，使用治疗前和治疗后的锥形束 CT 进行评估。患者接受了 4 颗第一前磨牙的拔除，然后采用骨骼或口内支抗进行前牙后移。连续的锥形束 CT 射线照相被注册到整个颅底和窝。通过标志点位移和颜色映射确定软组织和硬组织的变化。
上唇回缩集中在鼻唇沟和口角之间。下唇回缩伴随着颏下软组织的显著再分布。软组织变化与区域性面部肌肉活动密切相关。在中矢状面区域之外，软组织发生了显著的回缩（2-4mm）。使用骨骼支抗比口内支抗导致下唇回缩多 1.5mm，上颌和下颌切牙根尖的回缩更大。
两种治疗方式都伴随着前牙的回缩，出现了深刻的软组织变化。
