In order to clarify the effect of food hardness on masticatory movement, 20 healthy subjects were asked to chew 4 types of gumi-jelly on habitual chewing side. For the ten cycles beginning with the fifth cycle, the gape, masticatory width, cycle time and cumulative value of masseter muscular activity were compared among the four types of gumi-jelly.
1) The gape and masticatory width were smallest for the gumi-jelly containing 5% gelatin, and increased in order as the content of gelatin increased to 6.5%, 8%, and 9.5%. A significant difference was found between 5% and 6.5%, 9.5%, and between 6.5% and 8%, 9.5% for the gape, between 5% and 9.5%, 6.5% and 9.5%, 8% and 9.5% for the width.
2) The cycle time was smallest for the gumi-jelly containing 5% gelatin, and the value increased in order as the gelatin increased. A significant difference was found between 5% and 8%, 9.5%.
3) The masseter muscular activity was smallest for the 5%, and increased in order as the gelatin increased. A significant difference was found between all two types gumi-jelly except for the 6.5% and 8%.
4) From the above results it was concluded that the difference in the hardness of food causes changes in masticatory path, masticatory rhythm and masseter muscular activities and therefore has great effects on masticatory movement.
View full abstract