抄録
To investigate the effect of masticatory performance on the masticatory behavior, the masseter muscle activity during mastication of test food was measured in adult participants. Eighteen adult volunteers participated. Masticatory efficiency of each participant was obtained using the sieving test reported by Manly and Braley, and they were divided into two gropes (high efficiency group, H group; low efficiency group, L group). Three types of test food (rice cake, RC; peanuts, P; soft biscuits, SB) were prepared in 5g units. Electromyographic activities (EMG) of the masseter muscle were recorded using bipolar surface electrodes. The amplitude of EMG in the first five chewing cycles (E stage) and the final five chewing cycles (L stage) was averaged and compared statistically (Student's t-test). Significant difference in the number of chewing strokes until swallowing during mastication of RC, P or SB between two groups was not obtained. The masseter muscle activity at the E stage during mastication of RC, P or SB in the L group was significantly lower than that in the H group. In the H group, the masseter muscle activity at the E stage during mastication of the three test foods was significantly higher than that at the L stage. In contrast, the activity at the E stage during mastication of P was significantly lower than that at the L stage in the L group. These results suggest that the degree of masticatory efficiency may influence the masseter muscle activity at the E stage during mastication. [Jpn J Physiol 54 Suppl:S179 (2004)]
