Relationship between masseter muscle electromyographic activities and the position of the mandible / 南方医科大学学报

ABSTRACT

<p><b>OBJECTIVE</b>To investigate the changes in electromyographic activities of the temporal and masseter muscles at different positions of the mandible.</p><p><b>METHODS</b>Twenty orthodontic patients with Angle Class II malocclusion and mandibular retrusion (ANB<6°) aged 10-14 years were enrolled in this study. All the patients were treated with Forsus fixed functional appliance combined with MBT straight-wire appliance. The electromyographic activities of the temporal (T) and masseter (M) muscles before, during and after functional treatment were evaluated by assessing the average integrated electromyogram (EMG) and T/M ratio at clenching status in different mandibular positions.</p><p><b>RESULTS</b>After functional forward positioning of the mandible, the electromyographic activities of the temporal and masseter muscles decreased and T/M ratio increased significance at the clenching status (P<0.05).</p><p><b>CONCLUSION</b>The appliance insertion and activation is associated with a decreased EMG activity of the temporal and masseter muscles, and the T/M ratio is correlated to the position of the mandible.</p>