正畸扩弓治疗使得牙弓扩张增宽，唇肌张力增加而致唇舌肌的平衡破坏，从而容易引起拥挤复发，但在扩弓治疗中唇肌对扩张的牙弓也有一定的适应性，有文献报道被动扩弓治疗（加频屏推开颊肌使牙弓增宽）可使唇肌张力适应性减小，本文则旨在研究唇肌张力对模拟主动扩弓治疗的适应 Orthodontic expansion of the arch makes the dental arch widening widening lip lip tension caused by the balance of the damage of the tongue muscle, which easily lead to congested recurrence, but in the expansion of the lip muscle expansion of the dental arch also have some flexibility, there are Reported in the literature of passive expansion surgery (plus frequency screen to open the cheek muscles so that the dental arch widening) can reduce the adaptability of lip tension, this article aims to study lip tension on simulated active expansion of the treatment of adapting