Abstract
Purpose: To clarify the peripheral feedback mechanism of chewing various types of food, we analyzed the movement of the mandibular incisal point and the masseter muscular activity for the initial few cycles of mastication.
Method: Ten healthy subjects were asked to chew boiled fish paste, chewing gum, peanuts, and beef jerky, on their habitual chewing side, and for the first ten cycles of chewing, the gape, masticatory width, cycle time, and cumulative value of masseter muscular activities were compared among subjects, cycles, and the tested foods.
Results: Indicators were all largest at the first cycle, and thereafter decreased in the order of cycles. Though there were large variations among subjects and among cycles, the variations became small after the third cycle for chewing gum, after the fourth cycle for fish paste and peanuts, and after theseventh cycle for beef jerky. Comparing cycles, a significant difference was found between the first cycle and all the other cycles for indicators. Comparing the foods tested, no significant difference was found between any two foods up to the fourth cycle, and after the fifth cycle, significant differences were found between almost any two foods.
Conclusion: For the initial few cycles of mastication, in order to determine the amount of movement and muscular activity needed for the food, the masticatory movement changed with large variation. But once the amount has been determined, masticatory movement adapted to the texture of food takes place accompanied by minute changes.
