Objective:To explore the incisors moving modus of Angle Class I malocclusion with crowding treated by removing four first premolars .

• 方法:安氏I类错牙合牙列拥挤病例20例,均拔除4个第一前磨牙,采用方丝弓细丝弓技术矫治,牙性支抗(弱支抗)。