Objective To study the effects of biofeedback combined with the fixed functional appliance in the modification of mandible in patients with Angle Class Ⅱ malocclusion and retruded mandible.Methods A Iotal of 30 orthodontic patients were divided into two groups,all patients with retruded mandible and normal maxilla,ANB>6°,aged from 9 years and three months to 14 years and 11 months.All patients were treated with Forsus fixed functional appliance combined with MBT straight-wire appliance.Muscular activity of the superficial masseter muscle before,during,and after treatment.was evaluated by assessing the average integrated eleetromyogram (EMG) .The biofeedback was performed during functional treatment in the study group,the muscular activity of the superficial masseter muscle was turned into the signal which can be read and seen by patients,and the patient can control the muscular activity of the superficial masseter muscle in a certain extent under the help of instrument.After 6 weeks fixed functional appliance treatment,the biofeedback treatment was performed in the study group with the help of instrument and trained for 10 times,and the patients could trained by themselves for 20 minutes everyday.Results The biofeedback treatment was able to regulate the muscular activity of the masseter muscle and prevent the return of muscle function and the tendency to seat the condyle back toward the fossa,maintain the treatment effect;after biofeedback treatment the decreased postural EMG activity in the masseter muscle was steady,but without statistical significance (P>0.05).Conclusion The biofeedback treatment can maintain the muscular activity of the masseter muscle effectively,enhance the effect of functional treatment and keep the stability of the mandibular position.

OBJECTIVETo investigate the effect of the biofeedback in regulating the myoelectric activities of the masseter muscles.

METHODSTwenty 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.

RESULTSThe 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 1 day after treatment; t=4.86, P<0.05).

CONCLUSIONBiofeedback treatment can regulate the activities of the anterior temporal and masseter muscles and increase the T/M ratio in the clenching status.

Adolescent ; Biofeedback, Psychology ; Child ; Electromyography ; Humans ; Malocclusion, Angle Class II ; Mandible ; Masseter Muscle ; physiology ; Temporal Muscle ; physiology