固定式部分入れ歯の患者における主な咬合領域

The main occluding area in patients with fixed partial dentures.

抄録

食物の破砕は、機能的な歯頸部間の外接領域、すなわち「主咬合部」で行われることが明らかになっています。しかし、固定式部分床義歯（FPD）患者における主咬合域の位置については、定量的な検討がなされていないのが現状である。FPDの支台歯への荷重は，咀嚼初期の主咬合位によって過大に負荷される可能性がある．そこで，FPDの主な咬合領域の位置について検討した．本研究の目的は，FPD患者における主咬合部の位置を定量的に評価することである．そこで，歯列が揃っている対照群と第一大臼歯欠損を補うためにFPDを装着した患者との間で，主咬合領域の位置を比較した．主窩洞の位置を決定するための試験材料として，仮充填材を使用した．試験材の重心座標を算出し，基準軸に投影することで，主咬合領域の位置を評価した．その結果，FPD群の主咬合面の位置は，コントロール群よりも有意に後方で，安定しない傾向が見られた．咬合接触面積のほかに，ポンティック領域における歯根膜の存在が，FPD群とコントロール群の主咬合面の位置の違いをもたらしている可能性が示唆された．

It has become clear that food crushing is performed in the circumscribed region between functional cusps, that is, at "the main occluding area". However, the position of the main occluding area in patients with fixed partial dentures (FPDs) has not been investigated quantitatively yet. There is a possibility that the load onto the abutment teeth of FPDs is loaded excessively depending on the position of the main occluding area at the early stage of mastication. Therefore the position of the main occluding areas of the FPDs was investigated. The purpose of this study was to evaluate the position of the main occluding area in patients with FPDs quantitatively. We compared the position of the main occluding area between the control subjects who had complete dentition and the patients who wore FPDs for replacing missing first lower molars. Pieces of temporary filling material were used as test material to decide the position of the main occluding area. The centroid coordinate of the test material was calculated and projected onto the reference axis in order to evaluate the position of the main occluding area. Moreover, we recorded the occlusal contact areas at the intercuspal position in order to evaluate the relationship between the position of main occluding area and occlusal contacts.As a result, the position of the main occluding areas in the FPD group were significantly posterior to those in the control group and tended to be less stable. Besides occlusal contact area, existence of periodontal ligaments in the pontic region may cause the difference of the positions of the main occluding area between the FPD group and the control group.