Discrimination of clenches at varied jaw positions using autoregressive model coefficients of myoelectrical activities of anterior temporal and masseter muscles.

Abstract

During 10% maximum clenching at intercuspal, protruded, retruded contact and lateral positions, the surface electromyograms (EMG) of bilateral anterior temporal and masseter muscles of 20 normal subjects with intact natural dentitions were recorded. The autoregressive (AR) model of the sampled EMG was then built and the obtained coefficients of the AR model were accepted as featured parameters of the EMG. Finally Bayes' stepwise discriminant analysis was used for establishing discriminant functions of estimating low level clenches at varied jaw positions. It was found that total conformation rates of internal and external sample substitution (15 and 5 subjects) were 82.67% and 78% respectively; the discriminant effect between intercuspal and retruded contact position was not up to predicted standard. The results indicate that AR model coefficients may describe the characteristics of surface EMG of masticatory muscles and easily be used in multiple statistical analysis, from which the classification and diagnosis may be taken.