Temporal and masseter muscle activity in children and adults with normal occlusion. An electromyographic investigation.

Temporal and masseter muscle activity was investigated in male subjects with normal occlusion, 11 years (n = 23) and 25 years (n = 21) of age. Integrated EMG recordings were analysed quantitatively during maximal biting in intercuspal position and during chewing of peanuts. The results of the investigation revealed the following: 1. Masseter muscle activity was greater in the older than in the younger age group. 2. Temporal muscle activity was the same in both age groups. 3. Masseter muscle activity was increased in relation to temporal muscle activity in the older subjects. In the younger subjects the same activity was found in the two muscles. 4. For the temporal muscle the chewing activity was positively correlated to maximal biting activity in both age groups. For the masseter muscle a clear correlation between chewing and biting activity was found in the younger age group only. The difference in EMG activity found between children and adults may be attributed to age changes and/or an exercising effect of the masseter muscle occurring during maturation.