ABSTRACT
Objective:To investigate the oral-maxillofacial pain and t he surface electromyographic (EMG) activity of masseter muscles and anterior and posterior portions of temporalis muscles after experimental interference. Methods:A cast onlay of 0.5 mm in height was placed on the right low er first molar and remained for three days in 10 adult volunteers with normal oc clusion and without any symptom of TMD. The oral-maxillofacial pain was continu ously scored on a visual analogue scale(VAS)by the subjects before and after t he placement of the onlay. At the same time, the integral data of surface EMG we re recorded, and then the asymmetry index of the activity of bilateral muscles w as calculated. Results:Three days after the placement of the occ lusal highspot, all the subjects complained oral-maxillofacial pain. 8 of them had headache in right temporal region with VAS value of 1~4; the activity of tem poralis anterior at rest position of mandible was increased significantly (P