Abstract: Objective To investigate the effect of the biofeedback in regulating the myoelectric activities of the masseter muscles.
Methods Twenty orthodontic patients aged from 10 to 14 years with Angle Class II malocclusion, retrusive mandible, and an
ANB angle >6° were enrolled in this study. The muscular activities of the anterior temporal muscle and the masseter muscle
were evaluated before, during, and after biofeedback treatment by assessing the average integrated electromyogram and
temporal/masseter (T/M) ratio in the clenching status. Results The patients’ myoelectric activities of the anterior temporal
muscle was significantly increased after biofeedback treatment (P<0.05). The patients’ T/M ratio in the clenching status was
increased after the treatment (1.76±1.46 before treatment, 4.71±4.03 immediately after treatment, and 2.57±2.07 at 1day after
treatment; t=4.86, P<0.05). Conclusion Biofeedback treatment can regulate the activities of the anterior temporal and masseter
muscles and increase the T/M ratio in the clenching status.