Masseter muscle activity during the whole day in children and young adults

Changes in size and shape of the craniofacial skeleton during growth may be related to the masticatory muscle function in daily life. The purpose of t his study was to measure the masseter muscle activity during the whole day in children and to investigate the differences between children and young a dults. Fifteen children (7.8-13.0 years of age) and 30 young adults (20.3-3 4.7 years of age), who had acceptable occlusions without any remarkable ske letal discrepancy or temporomandibular disorder, were used as the subjects. In both children and young adults, most high-amplitude bursts of masseter muscle appeared mainly during mealtime, whereas a substantially larger numb er of low-amplitude ones were widely distributed throughout the whole day. The number and total duration of bursts of masseter muscle activity during the whole day was greater in children than in young adults, although signif icant differences were not found between the sexes. During daytime and slee p, both the number and total duration of bursts were greater in children. D uring mealtime, no significant differences in the number of bursts were fou nd between children and young adults, however, the duration of bursts tende d to be longer in children. It is concluded that the masseter muscle activi ty during the whole day is greater in children than in young adults.