Section Showing Minimal Intra-individual Variations in Masticatory Movement

To clarify the section showing minimal intraindividual variations in the movement of the mandibular incisal point during mastication of softened chewing gum.Twenty healthy subjects were asked to chew softened chewing gum on the habitual side for 20 seconds. The change in the spatial parameters (gape and masticatory width) and temporal parameter (cycle time) were investigated for 20 cycles from the first cycle. The coefficients of variation of these parameters were investigated for each of 10 consecutive cycles (first to eleventh series).The spatial and temporal parameters were maximal at the first cycle, decreased progressively until the fourth or fifth cycle, and then remained almost unchanged thereafter. The coefficients of variation of the parameters were maximal during the first series, decreased progressively until the fourth to sixth series, and then tended to increase gradually thereafter. Minimal coefficients of variation were observed during the fifth and sixth series for the gape, during the fifth series for the width, and during the fourth series for the cycle time.These results suggest that the ten cycles after the fourth to the sixth cycle was the section showing minimal intra-individual variations in the masticatory movement during the chewing of softened chewing gum.