伴长面型的Ⅲ类错(牙合)畸形不是矫形治疗的适应证。颏兜、矫治Ⅲ类错(牙合)的功能性矫治器和传统的前牵引头帽都会加重下颌骨的后下旋转,从而加重长面型。本文介绍了改良式前牵引装置的设计和制作步骤,可以适用于这类患者,并展示了用此方法矫治的一例病例。 材料和方法 根据生物力学原理,加在上颌骨的力应向前上通过其阻力中心,其垂直向分力会限制上颌骨过度的垂直向生长和上后牙的过度萌出,同时水平向分力将移动上颌向前以矫正上颌后缩。加在下颌 Malocclusion type Ⅲ malocclusion is not an indication of orthopedic therapy. Chinchip, orthodontic treatment of Class Ⅲ malocclusion and traditional headgear will increase the mandibular subsurface rotation, thereby aggravating the long surface type. This article describes the design and manufacturing steps for an improved front traction device that can be applied to such patients and shows an example of this approach. MATERIALS AND METHODS According to the biomechanical principle, the force applied to the maxilla should pass forward through its center of resistance, and its vertical component would limit the excessive vertical growth of the maxilla and the excessive eruption of the posterior teeth, while the horizontal component Move the maxilla forward to correct maxillary retraction. Add in the jaws