关键词: Headgear-activator, 鼻唇颏协调性, 软组织侧貌, 下颌后缩, Headgear-activator, coordination between nose，lips and chin, soft tissue profile, mandible retrusion

Abstract: Objective To investigate the effect of Headgearactivator appliance treating Class Ⅱ division 1 malocclusion on the coordination between nose,lip and the chin. Methods 38 patients with skeletal Angle ClassⅡmalocclusion were divided into two groups (Headgearactivator group and control group）,19 patients in each group.The Xray lateral cephalograms of two groups of patients were photographed before and after treatment and the angle and line spacing was measured.SPSS 11.0 software package was used to calculate the mean and the standard deviation.The paired ttest was performed to compare the changes of the measurements. Results LsE，LiE，U1Stm and the angle of NsLsFH，LsNsLi，LsNsPg′ decreased,SnStms，StmiMe′ and the angle of NsPg′FH，A′LsFH，B′LiFH，CmSnLs，LiB′Pg′， NsPg′FH， Z，GSnPg′ increased,and there was statistically significant difference（P<0.05). Conclusions Headgearactivator can reduce upper and lower lip protrusion,improve incompetent lips,recover the coordination between nose，lips and chin to a certain extend.Soft tissue profile tends to be nature and straightstyled.