The effect of orthognathic surgery on facial expressions and psychosocial well-being - a 4D preliminary study

面部身份和面部表情对我们的日常交流和自我认知有重大影响。由于骨骼和牙齿的协调，结合正畸和外科治疗，面部软组织的形态和功能的变化。然而，软组织动态变化的程度及其对面部表情的影响一直存在争议。据我们所知，目前还没有研究调查手术前后面部运动的差异是否会影响心理社会健康。这项前瞻性、单臂、单中心研究的目的是确定在手术前一天（T0）和手术后4个月（T1）接受正颌手术的患者的社会心理健康和面部表情。样本包括来自哥廷根大学医学中心正畸科的20名需要进行正颌手术的患者。面部运动的分析是通过非侵入性的四维立体摄影测量技术进行的，该系统通过动作捕捉系统每秒记录60张三维图像。这是一种创新的、客观的面部表情评价方法。每个病人做两种表情：1)最大的微笑和2)唇袋。测量了T0和T1之间的大小、速度和运动相似度的变化。在生活质量、自我效能和身体形象方面的社会心理健康是用一套有效的问卷来评估的。由于大多数患者生活质量的改善是进行正颌手术的主要动机，因此与口腔健康相关的生活质量被定义为主要结果。统计分析包括手术前后面部表情和心理健康的比较以及两者之间的相关性。我们假设正颌手术可以改善心理健康并改变面部运动。最大笑容的大小与生活质量之间存在正相关关系。本研究的结果有助于以患者为中心的术前和术后护理，并有助于优化软组织相关的正颌手术计划。

Facial identity and facial expressions have a major impact on our daily communication and self-perception. Due to skeletal and dental harmonization by combined orthodontic and surgical treatment, facial soft tissue changes in morphology and function. However, the extent of the dynamic soft tissue changes and the effect on facial expressions is discussed controversially. To the best of our knowledge, no studies exist investigating whether pre- and postsurgical differences in facial movement affect psychosocial well-being. The aim of this prospective, single-arm, monocentric study is to determine the psychosocial well-being and facial expressions of patients who undergo orthognathic surgery one day before (T0) and four months after (T1) surgery. The sample consists of 20 patients with need for orthognathic surgery from the department of orthodontics at the University Medical Center Goettingen. The analyses of facial movements are performed by non-invasive, four-dimensional stereophotogrammetry by a motion capture system, which records 60 three-dimensional images per second. It is an innovative and objective method to assess facial expressions. Each patient performs two expressions: 1) maximal smile and 2) lip purse. The change in magnitude, speed and motion similarity between T0 and T1 is measured. Psychosocial well-being in the fields of quality of life, self-efficacy and body image is assessed using a set of validated questionnaires. Since for most patients improvement in quality of life is the primary motivating factor for orthognathic surgery, the oral health related quality of life is defined as primary outcome. Statistical analysis includes the pre- and postsurgical comparison of facial expressions and psychosocial well-being as well as the correlations between both factors. We hypothesize that orthognathic surgery improves psychosocial well-being and changes facial movements. A positive correlation between the magnitude of maximal smile and quality of life is expected. The results of this study contribute to patient-centered pre- and postsurgical care and help to optimize soft-tissue related orthognathic surgery planning.