反是诸多错中最常见的畸形之一,根据反的类型可分为乳牙反、混合牙列反、恒牙反;根据反牙的多少又可以分为个别前牙反、前牙多数牙反、全牙列反、后牙列部分牙反;根据牙性与骨性分类可以分为真性下颌前突,由骨骼畸形所致,假性下前突,多为牙性所致,或者不良习惯所致。 Anti- is one of the most common deformities in many mistakes, according to the type of anti-乳 can be divided into deciduous teeth, mixed dentition  , permanent teeth  根; according to the number of anti- teeth can be divided into individual anterior teeth , the majority of the anterior teeth 反 inverted 全, the total dentition  后, posterior dentition part of the teeth  ; according to the classification of the teeth and bony can be divided into true mandibular protrusion, caused by the skeletal deformity, , Mostly caused by the dentine, or bad habits.