咀嚼時のヒト顎関節のバイオメカニクス

Biomechanics of the human temporomandibular joint during chewing.

抄録

咀嚼時のヒト顎関節の負荷に関する実験データは少ない。顆頭の開咬ストロークと閉咬ストロークの一致は、おそらく咀嚼中の関節の圧迫を示すと思われる。このような示唆をもとに、我々はラテックスで包装された食品を口の左右で咀嚼し、刻む際の関節の負荷について研究した。健常人10名の下顎運動を記録した。顆頭運動中心の移動距離は、最大開口時の移動距離を基準として正規化した。開口時と閉口時の顆頭運動軌跡の一致は、その起源を知ることなく判定した。咀嚼時、同側の顆頭は対側の顆頭よりも短い距離を移動した。咀嚼時およびチョッピング時には、すべての対側顆部が一致した運動パターンを示したが、同側顆部の数は有意に少なかった。これらの結果は、咀嚼とチョッピングの際、同側の関節は対側の関節よりも負荷が少なかったことを示唆している。

Experimental data on the loading of the human temporomandibular joint during chewing are scarce. Coincidence of the opening and closing chewing strokes of the condyles probably indicates compression in the joint during chewing. Using this indication, we studied the loading of the joint during chewing and chopping of a latex-packed food bolus on the left or right side of the mouth. Mandibular movements of ten healthy subjects were recorded. Distances traveled by the condylar kinematic centers were normalized with respect to the distances traveled during maximum opening. We judged coincidence of the opening and closing condylar movement traces without knowing their origin. When subjects chewed, the ipsilateral condyles traveled shorter distances than did the contralateral condyles. During chewing and chopping, all contralateral condyles showed a coincident movement pattern, while a significantly smaller number of ipsilateral condyles did. These results suggest that the ipsilateral joints were less heavily loaded during chewing and chopping than were the contralateral joints.