Abstract
To elucidate the relationship between masticatory ability and masticatory movements, mandibular movements and EMG were recorded at the same time that masticatory efficiency was measured by a sieve-analysis. Three different sets of chewing strokes and natural chewing were measured with peanuts. Eleven subjects with natural dentitions were chosen and tests were performed once a day and repeated for a total of five days.
1. As the setting strokes became fewer, the duration of movements became longer than natural chewing. The duration of movements on the first and second day tended to be longer than that on subsequent days. However the duration of movements was stable from the third day of measurement.
2. As the duration of the opening phase and EMG silence became longer and the extent of lateral displacement of the opening phase became smaller, the masticatory efficiency increased. This suggested that masticatory efficiency was affected more by masticatory movements during opening than closing.
3. It is suggested that, when the masticatory efficiency is measured by the sieve-analysis, at least two days for preliminary exercises are needed, and then the chewing strokes should be set at 20 and a sieve either of 10 or 16 mesh should be used.
