Electromyographic evaluation of anterior temporal and suprahyoid muscles using habitual methods to determine clinical...

The purpose of this study was to compare the electromyographic (EMG) activity of the anterior temporal and suprahyoid muscles using habitual methods to determine the clinical rest position. The sample included 26 healthy subjects with natural dentition, bilateral molar support, and bilateral molar Angle Class I occlusion. Bipolar surface electrodes were located on the right anterior temporal and suprahyoid muscles for EMG recordings. In each subject EMG activity was recorded while standing while performing the following jaw posture tasks: during light occlusal contact in the intercuspal position; during and after pronouncing the word Mississippi, during and after pronouncing the Spanish terms Sesenta y seis (English translation: sixty six); during and after pronouncing the word, business, during and after swallowing of saliva; and while maintaining their mandible in a relaxed posture. Anterior temporal EMG activity in the intercuspal position was significantly higher than all the other conditions. The same was observed in the suprahyoid muscles excepting after pronouncing the words Mississippi, and business. EMG activity recorded in the clinical rest position by means of phonetic methods, swallowing of saliva and maintaining the mandible in a relaxed posture did not show a significant difference. From an EMG point of view any of these methods could be used to determine clinical rest position.