材料和方法1.　研究对象:本组12例,男女各6例,年龄12—20岁,平均15岁,临床诊断Angle类错,反覆盖在3mm以上,但能退至切对刃状,全部不拔牙矫治。固定矫治器矫治6例,活动矫治器矫治6例。全部病例均戴用前方牵引器和后牙垫。2.　矫治方法:固定矫治器+前方牵引(直接牵引法):采 Materials and methods 1. Subjects: The group of 12 patients, 6 males and 6 females, aged 12-20 years, mean 15 years old, the clinical diagnosis of Angle class misdiagnosis, covering over 3mm repeatedly above, but can retreat to cut , All without tooth correction. Fixed appliance correction in 6 cases, active appliance correction in 6 cases. All cases were worn with front traction and posterior teeth  pad. 2. Correction method: fixed appliance + front traction (direct traction method): mining