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[Relationship between masseter muscle electromyographic activities and the position of the mandible]
Miao-qiong Huang1, Hang Feng, Can-can Zhou
1Department of Stomatology, Guangdong Academy of Medical Sciences and Guangdong General Hospital, Guangzhou 510080, China. milkh9@hotmail.com
Objective:
To investigate the changes in electromyographic activities of the temporal and masseter muscles at different positions of the mandible.
Methods:
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.
Results:
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).
Conclusion:
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.
