Abstract
The surface electromyographic (EMG) profiles were proposed for identifying normal muscle activity pattern by Winter et al (1987).
The purpose of this study was to investigate EMG profiles of masticatory muscles during deliberate unilateral gum chewing.
The EMG signals from bilateral masseter (Mm), anterior temporal (Ta) and anterior belly of digastric (Da) muscles of 5 healthy adults were recorded from for 90 seconds. The muscle activity was evaluated by the root mean-square (RMS) rectified EMG. Time averaging of each EMG over each chewing stroke was accomplished by normalizing each stroke period to 100% and then averaging each stroke at each interval over the chewing cycle to 0.3%. Normalization was achieved by setting the mean value of each subject's EMG over the chewing cycle to 100%.
The resuls were summarized as follows:
1. EMG profiles of masticatory muscles during deliberate unilateral gum chewing were made, which reduced inter-and intra-subject variability.
2. Each muscle showed a stable pattern of muscle activity at 60-75 seconds from the beginning of mastication.
3. EMG profiles in Mm of the working side were different from those of the non-working side, however, the profiles of Ta and Da were similar for both working and non-working sides.
