Objective:The purpose of this study was to investigate and analysis the correlation between position of chin and orthodontic treatment plan about extraction treatment. To develop a discriminant method to predict probability of orthodontic extraction.

• 目的:本研究通过对50例临床牙(牙合)畸形病例正畸治疗前X线头颅侧位片的研究,找出颏部位置形态在颅面部软硬组织侧貌形态中的作用,并分析颏部位置形态对临床矫治设计判断拔牙与否的影响,为临床诊断和矫治设计建立一种可行的判别方法。