Abstract
In order to find the effect of the size of the food on the masticatory movement a chewing gum that retained its size and consistency was selected as the test food and 10 normal subjects were asked to chew 1 piece (1G), 2 pieces (2G), 3 pieces (3G), and 4 pieces (4G) of chewing gum. Then the muscular activities of the masticatory muscles along with the velocity, rhythm, and path of the masticatory movement of the 10 cycles beginning in the fifth cycle of each chewing session were calculated and analyzed. The results were as follows.
1) The amount of opening and the masticatory width increased as the size of the food increased, and a statistically significant difference was found between each and every session for the amount of opening and between 1 G and 3G, and between 1G and 4G for the masticatory width.
2) The rhythm of the movement
The occluding time remained the same regardless of the size of the food. No significant difference was found between any session. The opening time, closing time, and cycle time increased slightly as the size of the food increased. Significant differences were found between 1 G and 4G and between 2G and 4G.
3) The velocity of the movement
The maximum velocity of opening and closing increased as the size of the food increased. Significant differences were found between 1G and the other sessions and between 2G and 4G for the maximum opening velocity, and between 1 G and other sessions for the maximum closing velocity.
4) The muscular activities
The cumulative value of masseter and temporal muscles increased as the size of the food increased. Significant differences were found between 1G and the other sessions for masseter muscle and between 1G and 3G, and between 1 G and 4G for temporal muscle.
5) From the above results it was clear that as the size of the food increased the quantitative indicators of masticatory movement, the path, rhythm and velocity, changed along with one or all of the indicators of the muscular activities. This could lead to the thought that the changes in the sensory input from the periphery has affected the masticatory movement.
