Abstract
To understand age and sex differences on masticatory functions, the following experiments were performed on 46 subjects, who have intact dentition without stomatognathic dysfunction. The subjects were classified into four groups: 4 elderly men (59.2±6.8 years), 6 elderly women (60.5±3.5 years), 26 young men (24.1±2.1 years) and 10 young women (23.1±2.6 years). And the masticatory efficiency and muscle activity during chewing the testing gumi-jelly (Glico Co., Osaka) were examined.
Firstly, the masticatory efficiency was evaluated by using the amount of gelatin dissolved from the surface of the gumi-jelly after chewing a given number of times. This technique was based on the fact that gelatin was the only protein contained in the gumi-jelly, and the amount of dissolved gelatin was almost proportional to the surface area of the gumi-jelly.
Secondly, in order to examine the rhythm of muscle activity and the integrated muscle activity during chewing the gumi-jelly, electromyographic activities were obtained from the anterior part of temporal muscles and masseter muscles with surface electrodes bilaterally.
Consequently, there were no significant differences between the four groups concerning the amount of dissolved gelatin and the stability of muscle activity. The integrated muscle activity per stroke of young subjects tended to be higher than that of elderly subjects. And that of men also tended to be higher than that of women.
