10 咬合高径が筋線維伝導速度および筋疲労に及ぼす影響 (第439回 大阪歯科学会例会)

抄録

I studied the influence of occlusal vertical dimension on the muscle fiber conduction velocity (MFCV) and muscle fatigue in the human temporal and masseter muscles of six normal subjects between 22 and 30 years of age. The vertical dimension of occlusion was changed from the intercuspal position to a maximum opening of 21.0mm using three different occlusal splints. The subjects were asked to fatigue the muscles by contracting at each occlusal vertical dimension. EMG responses were evoked by electrical stimulation, and the EMG signals were detected by a linear array of surface electrodes placed along the muscle fibers. The MFCV was calculated from the time delay between adjacent EMG signals. I found that the higher the vertical dimension of occlusion, the lower the MFCV. In addition, at a given vertical dimension, the greater the muscle fatigue, the lower the MFCV. The endurance time also decreased with increases in vertical dimension. These results indicate that vertical dimension is an important parameter in the propagation velocity of action potentials and in the development of static muscle fatigue.