Abstract
This study was carried out to evaluate usefullness of silent period of masseter electromyography (EMG) for diagnosis of unstable occlusion of full denture wearers one month after setting. Using bipolar surface electrodes, masseter EMG during tapping movement (72/min) was recorded. The latency (S. P. L.), duration (S. P. D.) and frequency of the silent period were measured on the EMG. Occlusal sound was checked simultaneously in order to estimate occlusal condition. The results were summerized as follows:
1. Ten subjects with stable occlusion were selected for a control group. Mean value and standard deviation of S. P. L., S. P. D., and frequency of the silent period obtained from the control group were 12.0±2.4 msec, 18.6±5.4 msec and 80%, respectively.
2. Latency and frequency of the silent period were not very useful parameters for diagnosis of unstable occlusion.
3. S. P. D. was found to be a useful parameter for diagnosis of unstable occlusion. In stable occlusion, S. P. D. was considerably short and less variable.
4. When S. P. D. was over 35 msec and frequency of the silent period was very few, the patient was suspected of having arithrosis of temporomandiblar joint.
