Abstract
The purpose of this study was to investigate the alternation of the activity of the masticatory muscles on the working and balancing sides during dentitional development.
A total of thirty persons were used in the study; 10 with deciduous dentition,10 with mixed dentition,10 with permanent dentition. EMGs were recorded from the anterior temporalis muscles and masseter muscles on both the working and balancing sides during chewing of boiled fish cake paste, chewing-gum and chewing of dried cuttlefish on both the habitual and non-habitual sides. Each muscle activity, while chewing, of 4 muscles (TW: the anterior temporalis muscle on working side, MW: the masseter muscle on the working side, TB: the anterior temporalis muscle on balancing side, MB: the masseter muscle on balancing side) and the ratio of each muscle activity to TAM (total muscle activity = TW+MW+TB+MB) were evaluated.
The results obtained in the present study were as follows:
1) There were significant differences (p<0.01) in EMG activities among muscles in all groups.
2) Muscle activity of MW showed a significant increase in accordance with denditional development from deciduous to permanent dentition (p<0.01).
3) Comparing the ratio of each muscle activity to TAM, no significant differences among foods were found.
4) Compared to children, the ratio of MW activity to TAM in adults showed a significant increase, whereas decrease in TB (p<0.01).
The results suggests that the alternation of masticatory muscles during dentitional development could be associated with the anatomical growth of muscles and the functional maturation of mastication.
