1999 Volume 6 Issue 1 Pages 79-84
The purpose of the study was to investigate the characteristics of mastication in infants by evaluating the electromyographic chewing rhythm of the masticatory muscles and VTR, and to discuss the development of masticatory function in infants at the stage of the weaning period. Sixty subjects were divided into the following five groups, GO (the sucking group as a control), G1 (up to 8 wks after the initiation of weaning), G2 (up to 16 wks), G3 (up to 24 wks) and G4 ( more than 25 wks) .
When compared to the control both the chewing cycle time and the burst duration in the temporal muscle became significantly longer in 01 and 02, and then declined gradually in G3 and G4. The mastication pattern of infants can be classified into three types, such as continuous tongue compression, cyclic tongue compression and the maturation type. The frequency of the maturation type was significantly increased from 01 (2.6%) to 04 (49.5%) as the time proceeded from the initiation of weaning.
The coincidence of the bursts of the temporal muscle and the suprahyoid muscles was recognized during each chewing cycle in the earlier period of weaning, while the burst timing of the both muscles were, thereafter, differentiated gradually. Therefore, the development of masticatory function in the weaning period infants disclosed that the function of the jaw closing muscle and of the jaw opening muscles is differentiated gradually.
