Prediction of different mandibular activities by EMG signal levels

The purpose of this study was to make observations of electromyographic (EMG) signal levels from a group of individuals to describe different mandibular tasks and use them as predictors of these activities. The sample consisted of 22 volunteer subjects (12 women and 10 men) with mean values for age, weight and height of 29.3 years, 69 kg and 168 cm respectively. Three separate recording sessions were performed for each subject. During each session the subjects were asked to perform different voluntary mandibular tasks. The EMG activity for each task was recorded from the anterior temporalis (T-a) and masseter muscles (M-m) bilaterally. The EMG recordings were related to task, session, task-session interaction, gender, age, weight and height using SAS version 6.12. The EMG data from the four muscles were considered as covariates to classify tasks. Overall, 78% of the group tasks were correctly classified. When the masticatory activities were classified as high and low EMG signal level group, the overall classification rate improved with an accuracy of 88%, sensitivity of 86%, specificity of 88%, positive predictive value of 76% and negative predictive value of 94%. The tasks, sessions, task-session interactions, gender, age, weight and height did not have any significant effect on the EMG recordings. It can be concluded that distinguishing among different mandibular tasks of a subject can be achieved when the individual EMG signal levels were compared with the EMG signal levels of subjects that were used to describe different mandibular activities.