[Electromyography of perioral muscles in the cleft lip and palate patients with crossbite].

In this study, twenty-nine cleft lip and palate patients with anterior crossbite were chosen as study group and twenty-eight normal children, twenty-seven patients with anterior crossbite as the control groups. All subjects were examined with EMG, and found some characters of the perioral muscles activity of the cleft patients. (1) The electromyographic amplitude of the upper lip and chin muscles was higher in cleft patients than that of other two groups during swallowing of saliva (2) Activity of chin muscle in cleft patients and crossbite patients in rest position were higher than that of normal occlusion (3) The Asymmetry index of the activity of upper lip muscle in every functional positions of the cleft patients are higher than ther groups. The abnormal activity of perioral muscles of the cleft patients demonstrate that functional repairment of cleft lip and needed lip bumper are necessary.