Abstract
The influence of occlusal vertical dimension on the muscle fiber conduction velocity (MFCV) and EMG frequency parameters were studied in the human temporal muscle in four healthy subjects (21-29 yrs. old). The occlusal vertical dimension was changed from intercuspal position (ICP) to maximum bite-raising position (22.0mm) by applying six different occlusal splints to the habitual opening-closing movement path. The EMG activities at 10, 30 and 50% maximum voluntary contraction were measured at each vertical dimension. The EMG signals were detected with a surface linear electrode array with 7 contacts placed along the muscle fibers. The MFCV was calculated from the time delay between adjacent EMG signals. The frequency parameters were 10, 25, 50 and 75% cumulative power functions and mean power frequency.The results obtained were as follows:
1. The MFCV was increased according to the increase of the contraction level, but decreased accoding to the increase of the occlusal vertical dimension.
2. Each frequency parameter was shifted lower according to the increase of the occlusal vertical dimension.
3. The significant correlation (p<0.05) between MFCV and frequency parameters was shown at a high contraction level.
