乳前牙反合较为常见,临床上对反覆盖小反覆合深的乳前牙反合常采用下前牙塑料联冠斜面导板矫治器矫治,疗效尚可。但病例选择不当,就会导致治疗的失败。本文从乳牙牙齿的位置,结合本人临床工作实践,分析治疗失败的原因,并进一步探讨改进的方法。病例报告:病例1。李×,男,5岁,牙(?)近中尖对尖,(?)反合,反覆合3mm,反覆盖1.5mm,下颌略前突,前牙排列整齐。诊断:1.安氏Ⅲ类;2.毛氏Ⅱ′。矫治设计:下前牙塑料联冠外面导板。每周复诊一次,矫治2周,切牙对刃,(?)所对的 Anterior cruciate ligament is more common in clinical practice, the anti-retrograde cover of small anterior congenital anterior cruciate ligament is often used under the crown plastic bevel guide plate appliance, the effect is acceptable. However, improper case selection will lead to the failure of treatment. This article from the position of deciduous teeth, combined with my clinical practice, analyze the causes of treatment failure, and to further explore the improved method. Case Report: Case 1 Lee ×, male, 5 years old, teeth (?) Near the tip of the sharp, (?) Anti-conflagration, repeated cover 3mm, cover 1.5mm repeatedly, slightly anterior mandibular protrusion, front teeth neatly arranged. Diagnosis: 1. Class III; 2. Mao Ⅱ '. Correctional design: under the plastic front crown under the outer guide plate. Weekly referral once, correction 2 weeks, incisor to edge, (?) Right