Abstract
To find the specific parameters that differentiate craniomandibular disorder patients (CMD-group) from normal subjects (normal-group), the temporal muscle and masseter muscle EMGs were measured during a sustained maximum clenching and gum-chewing period.
In power spectral analysis of EMGs during clenching, the power increased significantly in thenormal-group than those of the CMD-group in the 0-75 Hz frequency range. Although the powerdecreased over the 200 Hz range in the normal-group, there was little change in the CMD-group.The power spectra changing patterns were classified into 4 types according to the different combinationsof the 0-75 Hz and over 200 Hz range. Twenty five out of 30 subjects in the normal-group, and9 out of 30 from the CMD-group were classified into type I which indicated an increasing lowfrequency power with a decreasing high frequency power. Normal range of the coefficient variationof cycle, duration, and duration/cycle were set at mean±3 SD of the normal-group. Twenty subjectsin the CMD-group were beyond the normal range in at least one of the three parameters. By utilizingthe combinations of the power spectra changing pattern and masticatory rhythm, 93.2% of CMD-group were found to be parafunctional.
This EMG analysis is considered to be an effective method in evaluating the functions of mandibleof those who are suffering from craniomandibular disorders.
