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下顎頭に骨変化を有する骨格性Ⅱ級患者の顎矯正手術後の咬合の安定性に対する手術時の下顎骨片移動位置の検討
平野, 成美;梶井, 貴史;泉, 喜和子;玉置, 幸雄;細川, 周一;松沢, 祐介
Permalink : http://hdl.handle.net/2115/86834
KEYWORDS : 下顎頭の骨変化;外科的矯正治療;顎矯正手術;下顎近位骨片;下顎遠位骨片;osseous changes of the condyle of the temporomandibular joint;surgical orthodontic treatment;orthognathic surgery;proximal and distal segments of the mandible
Abstract
骨格性Ⅱ級患者では顎矯正手術後に骨片の位置や咬合に後戻りがみられる症例が比較的多いことが報告されている．下顎頭に骨変化を有する骨格性Ⅱ級患者で外科的矯正治療を受けたものについて，顎矯正手術による骨片の移動様相が咬合の安定性に関連するかを検討することを目的とした．
初診のパノラマエックス線画像で下顎頭の骨変化が明確であり，上下顎移動術を受けて動的治療を終えた骨格性Ⅱ級患者8症例を抽出し，保定観察時のoverjetが+4.5 mm以上のものを後戻り群，それ以外を安定群と定義した．資料として，初診時，手術直後，保定観察時に採得したパノラマエックス線写真と側面セファログラムを用いた．
後戻り群の4 症例全てで保定観察時に下顎頭のさらなる骨変化が認められた．セファロ分析値より手術時の下顎近位骨片の反時計回りの回転が両群ともに認められた．下顎遠位骨片の反時計回りの回転は安定群で認められたが後戻り群では認められなかった．結果として，下顎角は安定群では術前後で変化していなかったが，後戻り群では術後に開大していた．
下顎頭に骨変化を有する骨格性Ⅱ級患者のうちで顎矯正手術後に咬合の後戻りを認める症例では，下顎頭のさらなる骨変化が後戻りの原因の1 つであることが示唆された．下顎頭のさらなる骨変化には顎矯正手術時の下顎の近位骨片と遠位骨片の位置決めが関与することが示唆された．
This study evaluates whether mandibular proximal and distal segment positions during orthognathic surgery affect the stability of surgical orthodontic treatment in skeletal Class II orthodontic patients with osseous changes of the mandibular condyle of the temporomandibular joint (TMJ). Eight Japanese women with Class II malocclusion with osseous changes of the mandibular condyle were examined. All cases underwent double-jaw surgery. Panoramic radiographs at pre- and posttreatment were used to evaluate osseous changes of the mandibular condyle of the TMJ. Lateral cephalograms at pretreatment, just after double-jaw surgery, and posttreatment were used to evaluate changes in mandibular proxi mal and distal segment positions during double-jaw surgery. Further, osseous changes of the mandibular condyle were observed in four cases (unstable group). Compared with the other four cases (stable group), counterclockwise rotation of the distal segment of the mandible was not shown in the unstable group. Counterclockwise rotation of the mesial segment was shown in both groups. Consequently, the gonial angle was increased after double-jaw surgery in the unstable group. Unstable occlusion in skeletal Class II patients with osseous c hanges of the TMJ condyle was attributable to further osseous changes of the TMJ condyle. Moreover, mandibular proximal and distal segment positions during orthognathic surgery may affect subsequent osseous changes of the TMJ condyle.
This study evaluates whether mandibular proximal and distal segment positions during orthognathic surgery affect the stability of surgical orthodontic treatment in skeletal Class II orthodontic patients with osseous changes of the mandibular condyle of the temporomandibular joint (TMJ). Eight Japanese women with Class II malocclusion with osseous changes of the mandibular condyle were examined. All cases underwent double-jaw surgery. Panoramic radiographs at pre- and posttreatment were used to evaluate osseous changes of the mandibular condyle of the TMJ. Lateral cephalograms at pretreatment, just after double-jaw surgery, and posttreatment were used to evaluate changes in mandibular proxi mal and distal segment positions during double-jaw surgery. Further, osseous changes of the mandibular condyle were observed in four cases (unstable group). Compared with the other four cases (stable group), counterclockwise rotation of the distal segment of the mandible was not shown in the unstable group. Counterclockwise rotation of the mesial segment was shown in both groups. Consequently, the gonial angle was increased after double-jaw surgery in the unstable group. Unstable occlusion in skeletal Class II patients with osseous c hanges of the TMJ condyle was attributable to further osseous changes of the TMJ condyle. Moreover, mandibular proximal and distal segment positions during orthognathic surgery may affect subsequent osseous changes of the TMJ condyle.
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