背景：阻塞性睡眠呼吸終止症為睡眠呼吸障礙門診常見的疾病，患者除了白天清醒時的精神狀況不佳，嚴重的患者甚至會威脅其生命。治療阻塞性睡眠呼吸終止症候群的方法有很多，其中包括促使下顎骨前移以改變舌根位置的口腔裝置或以手術將下顎骨及頦部的向前移動以改變下顎骨及舌骨的位置以使頦舌肌（genioglossus muscle）和頦舌骨肌（geniohyoid muscle）帶動舌頭向前遠離後咽壁，其治療原理皆為因增加了後呼吸道空間 (Posterior airway space, PAS)而減少了阻塞性睡眠呼吸終止的產生。而臨床上針對骨性第三級咬合異常的病人，常規上須採用矯正搭配雙側垂直性下顎骨上升枝截骨術的正顎手術來治療，但雙側垂直性下顎骨上升枝的截骨手術卻可能因下顎骨及頦舌肌或頦舌骨肌連附點的後退而造成後呼吸道空間(PAS)的減少。因此本研究的目的為分析因骨性第三級異常咬合而接受雙側垂直性下顎骨上升枝截骨術正顎手術的患者其術前術後之側顱X光片，藉由測量其術前術後之PAS變化及舌骨位置的變化來觀察雙側垂直性下顎骨上升枝截骨手術是否會造成術後PAS的減少。材料與方法：本研究分析因骨性第三級異常咬合而接受雙側垂直性下顎骨上升枝截骨術正顎手術的患者其術前術後之側顱X光片，藉由測量其術前術後之PAS變化來觀察雙側垂直性下顎骨上升枝截骨手術是否會造成術後PAS的減少並增加其產生阻塞性睡眠呼吸終止症的風險，其結果以多元線性迴歸採逐步迴歸法進行統計分析。研究的樣本為45位第三級骨性咬合異常的患者，於2008至2010年間於中山醫學大學齒顎矯正科及口腔顎面外科接受齒顎矯正合併正顎手術的治療，男女比為29:16，年齡分佈為31.3歲 (20.2-44.3歲)。結果：我們的研究證實令下顎骨後退的正顎手術的確會造成呼吸道的狹窄，我們也建立了PAS變化與下顎骨後退量之線性函數關係，即術前PAS的距離及下顎骨平均後退的量可以預測術後PAS的值；而術前術後之SNB及其變化量以及下顎骨頦部前移手術中所前移的量可以預測術前術後NSH的變化。結語：我們的研究對接受下顎骨後退正顎手術的患者得以在術前評估其術後發生後呼吸道空間的減少的可能性，進而預測該手術對患者本身可能帶來阻塞性睡眠呼吸終止症的風險效應。
Background: Obstructive sleep apnea is a disorder characterized by abnormal breathing in sleep and sleep fragmentation. Patients with obstructive sleep apnea often complain of excessive daytime somnolence. In more advanced severe cases, the situation might become life-threatening. In the treatment of obstructive sleep apnea, a mandible protrusive device that pulls the mandible forward together with tongue forward has been used successfully. Mandibular advancement surgery has also been used to improve obstructive sleep apnea by the suspected effect of pulling of the tongue forward off the pharyngeal wall. The effect is created by anteriorly moving the insertion of the genioglossus and geniohyoid muscles that increased the distance of posterior airway space (PAS). In our daily clinic routine, bilateral vertical ramus osteotomy is used for mandibular setback to correct the skeletal Class III malocclusion. As the result of mandibular setback after orthognathic surgery, the backward of the insertion of the genioglossus and geniohyoid muscles might decreased the posterior airway space. Material and Methods: In this study, we analysed the preoperative and postoperative cephalometric films of the patients who received bilateral vertical ramus osteotomy for correcting their skeletal Class III malocclusion. The changes of PAS between preoperative and postoperative condition were investigated by stepwise multiple linear regression. Results: Our study revealed that the PAS will be decreased after orthognathic mandibular setback surgery, and the predictive equations were also been established. The preoperative PAS and average mandibular setback distance can be used to predict the postoperative PAS, and the preoperative/postoperative SNB combine with the chin advancement distance can be used to predict the changes of NSH. Conclusion: Our results provide the possibility to evaluating the changes of posterior airway space in the patient who will receive the orthognathic surgery for mandibular setback preoperatively, and we can also evaluate the risk of developing obstructive sleep apnea after bilateral vertical ramus osteotomy.
