材料和方法从北京市解放军总后幼儿园3～5岁儿童704名中,选出汉族正常乳牙(牙合)207人作为测量对象,其中男118人,女89人,平均年龄4.0岁.选择标准:发育正常、颜面谐调,牙齿数目正常,排列整齐,覆(牙合)、覆盖正常、上下(牙合)牙弓中线相对,无颞颌关节病史及面部外伤史.测量方法:张口度指最大张口时上下切牙间距加覆(牙合).测量时令受试者端坐,头直立,面部肌肉放松,首先用笔于下中切牙唇面标记正中(牙合)位时上下切牙的覆(牙合)位置A点,随请受试者最大限度张口,用面规测量上中切牙近中切角处至A点的距离即为张口度。(如图) MATERIALS AND METHODS Totally 207 Chinese Han normal deciduous teeth were selected from 704 children aged 3 to 5 years in the General Post-Kindergarten of Beijing Municipal People's Liberation Army, including 118 males and 89 females, with an average age of 4.0 years. : Normal development, face harmonization, the normal number of teeth, arranged neatly, covered (occlusal), covering the normal, upper and lower occlusal arch line relative, no history of temporomandibular joint and facial trauma history.Measurement: Open the mouth when the distance between the upper and lower incisors and overlays (occlusal.) Measurement of seasonal subjects to sit, head upright, facial muscles relax, first with the pen in the middle of the incisor face Cover (occlusal) position A point, with the subjects asked to maximize the mouth opening, with facial measurements of the incisors at the mid-incision angle to A point distance is the mouth opening. (Pictured)