拔除下顎第一大臼齒以改善牙周缺損之病例報告

Orthodontic Treatment to Improve Periodontal Defect in A Patient with Lower First Molar Extraction – A Case Report

23 歲男性患者，主訴為下唇較前突及下排前牙不整齊並向前擠出；其上顎兩側與下顎左側之第一小臼齒共三顆牙齒已缺失，造成下牙弓形狀之左右明顯不對稱及下顎前牙正中線向左偏移至少6毫米。矯正治療計畫為將已有嚴重牙根尖發炎之左下第一大臼齒拔除而不拔除右下小臼齒。治療後之下齒列正中線，設定為接近41與42之間，即比治療前更加偏移至左側。矯正治療完成時，右側為安格氏一級咬合關係，左側為安格氏二級咬合關係。本病例之特色為：拔牙空間要先提供給擁擠之下顎前牙以獲取理想的水平與垂直覆咬，並以迷你骨釘做錨定，且需直接施力於迷你骨釘，以防牙齒傾斜或挺出等負面作用；剩餘的拔牙空間可因此大量減少，使左下第二大臼齒向前移動距離與所需時間明顯縮短。患者之下顎智齒，左右都有水平阻生現象。尤其是左下智齒的牙冠與左下第二大臼齒之遠心側因過於貼近，已有牙周組織與齒槽骨之缺損。如過早拔除左下智齒，會留下此缺陷並困擾日後之牙周維護。在制定治療計畫時，先確立拔牙之先後順序：必須在左下第二大臼齒前移運動完成、第二大臼齒與其後方之智齒被分隔開約3毫米、以及確認齒槽骨高度有所增加後，才拔除左下智齒。將矯正及牙周病學兩專科之考量加以整合，並選擇最有利於患者之治療方式，可避免矯正術後之牙周手術風險及復需求。患者之矯正過程順利，治療結果穩定，已定期追蹤滿四年。

A 23 year-old male came with chief complaint of lower anterior crowding and protrusive lower lip. Dental examination revealed missing teeth 14, 24 and 34 and horizontally impacted 38 and 48. Poor prognosis of tooth 36 was found after evaluation. Anterior cross bite and open bite at his left side occlusion were also seen. In this case, removal of teeth 36 and 38 were selected instead of 44 extraction. Thus the timing and proper sequence of tooth extraction become critical. The biomechanics of tooth movement was designed to ensure that all teeth are in functional occlusion and the lower left second molar have long-lasting healthy periodontal condition after treatment. With the assist of temporary anchorage devices (TADs), all the patient's lower teeth were moved within lower dental arch toward the extraction space of 36. This treatment procedure was addressed in two aspects: 1) protraction of 37 can be in a shorter span to avoid tooth tipping and the treatment duration can be reduced; 2) prevention of periodontal complications at the distal aspect of 37. It is concluded that implementing the periodontal consideration into orthodontics has contributed to a successful and beneficial treatment outcome. The treatment goals were achieved; the treatment results were stable in four-year follow up.