Development of masticatory function evaluated through electromyographic studies for masticatory muscles in children
2006 Volume 13 Issue 1 Pages 11-15
Details
2006 Volume 13 Issue 1 Pages 11-15
In order to evaluate the development of masticatory function in children, we have observed the accuracy of jaw movements, the silent period, the muscle fiber conduction velocity (MFCV) and the maximum bite force (MBF) from children to adults.
1. Accuracy of the jaw movement rhythm was significantly inferior in children to that of adults; however the accuracy was improved with age.
2. The duration of the silent period (SPD) during tooth tapping was significantly longer about 2 ms in children than in adults in both temporal and masseter muscles. In addition, SPD in the masseter muscle was observed by applying chin tap stimulation during both clenching teeth (10%, 50%, and the maximum) and biting on a transducer (50N, 100N and the maximum) . When comparing SPDs between children and adults at the same voluntary efforts, the children exhibited significantly longer SPD than that of adults. The results suggest that SPD was positively influenced by the strength of the background activities of the muscles and that immaturity of the masseter in terms of muscle activity could affect the SPD.
3. The muscle fiber conduction velocity (MFCV) of the masseter muscle in children was significantly slower than adults, whereas the biceps muscle of upper arm was not changed due to development. Change of MFCV may be due to the differences of proportion of the muscle fiber types such as fast twitch and slow twitch fiber with development.
4. Though the maximum bite force (MBF) showed an increase with age, it was more enhanced during the late mixed and permanent dentition. As the MBF increased, the speed for MBF also accelerated, hence the momentary bite force of the masticatory muscle increased with age.
From these results, the children were demonstrated that their masticatory function was inferior in terms of not only the power of masticatory muscles but also the accuracy of the jaw motion to that of adults, and was developed with age.
