The investigate the change of the electromyographic activity about digastrics anterior after RW-splint treatment for one week and two monthsin order to offer the theoretic basis for class Ⅱ malocclusion deformity patients with temporomandibular disorders (temporomandibular, disorders, TMD).

After wearing RW-splint successfully, the electromyographic activities of diagastric anterior before and 1 weeks, 2 months after RW-splint treatment were detected by EMG Ⅱ type surface EMG measuring instrument with BioPAK system.

There was no statistically difference exist (P ＞ 0. 05) in the EMG records of digastric anterior muscle during swallowing position after one week's RW-splint treatment. After 2 months treatment compared with pre-treatment, EMG records of digastric anterior muscle during swallowing position were decreased respectively, which showed remarkable significance (P ＜ 0. 05). However, after 1 week, 2 months treatment compared with pre-treatment, EMG records of digastric anterior during MMP, which showed no statistically signifcant difference (P ＞ 0. 05).

Extension time of RW-splint worn can change the electromyographic activity of digastrics anterior.