顏面不對稱暨三級異常咬合的手術矯正治療－－病例報告

Surgical-Orthodontic Treatment of Class III Malocclusion with Facial Asymmetry — A Case Report

顏面不對稱往往會造成美觀及功能上的問題，在臨床上，下顎比上顎更常見不對稱的發生，可能來自於骨骼、齒列、或軟組織的問題而造成不對稱的外觀結果，當病患有顏面不對稱的主訴時，應仔細檢查診斷其病因來源。有研究指出，針對下臉部的不對稱，觀察其下顎角、下顎枝、及下頷聯合的偏移程度及方向，與矯正合併手術治療的預後相關。本報告提出一位具上述問題的病例，其下顎角、下顎枝與下頷聯合都偏向右側，觀察電腦斷層發現其相對於中線，下顎角、下顎枝的偏移程度大於下頷聯合。患者為20歲男性，主訴為臉型不對稱及下巴突出。臨床檢查發現明顯左右臉不對稱、下巴前突和往右偏移；口內咬合可見右側錯咬，前牙對緣咬合（edge to edge），右側犬齒與臼齒為安格氏第一級咬合、左側犬齒與臼齒為安格氏第三級咬合。分析電腦斷層影像顯示左右側下顎角與下頷點都往右側偏移，並且左右側下顎角往右側偏移的量比下頷點的偏移量多。診斷為骨性第三級咬合且合併下顎前突，顏面不對稱。患者經過下顎後退手術合併全口齒列矯正治療後，顏面美觀及咬合功能都有大幅度改善。本報告將討論此一顏面不對稱下顎前突患者的治療過程及變化，並探討此類患者的診斷及治療預後的原則。

Facial asymmetry affects more frequently on the lower face than the upper face. Significant facial asymmetry compromises both occlusal function and facial esthetics. The etiology of facial asymmetry may be skeletal, dental, and soft tissue components of dentofacial structures. Correct diagnosis and appropriate treatment planning are very important in the management of the orthodontic patients with the chief complaint of facial asymmetry. Facial asymmetry in lower face can be clearly detected through the examination on chin deviation and asymmetry of bilateral gonial angle regions. The amount and the direction of deviation usually reveals the dental compensation in the transverse aspect before treatment. Thus the dental axis correction is more complicated in patients with asymmetric mandible. Herein we report a case presenting chin deviation and obvious asymmetry of bilateral gonial angles. The contour of gonial angle is more prominent at the ipsilateral side compared to the chin deviation. This is a case of 22-year-old male, who complained about facial asymmetry and chin protrusion. Clinical examination revealed acute nasolabial angle, mandible prognathism, chin deviation to right side. The prominent gonial angle was much more prominent at the right side, which was ipsilateral to the side of chin deviation. Cephalomatric analysis showed skeletal Class III malocclusion with mandible prognathism and mild dental compensation. Postero-anterior cephalomatric analysis showed mandible deviation to the right side and obvious asymmetry at bilateral ramus and gonial angle. The mild occlusal plane canting was noted. The treatment plan included non-extraction full-mouth orthodontic treatment and bilateral sagittal split osteotomy (BSSO) mandibular surgery for setback and side shift. Upper arch distalization by upper bilateral miniscrews was conducted to retract upper incisor for decompensation in the pre-surgical orthodontic treatment. The dental compensation in the transverse aspect was eliminated with the cross-elastics and the bucco-lingual torque correction of posterior teeth. In mandibular surgery, over-correction of mandible side-shift movement to the left side was done for more correction of chin deviation. The treatment outcome showed stable occlusion and obvious improvement of facial asymmetry.