大家都知道,牙齿的咬合是上前牙盖着下前牙的牙冠约1/3的部分。如果这个情况相反,下前牙遮盖着上前牙的牙冠,医学上则称为前牙反(牙合),俗称“地包天”或“下兜齿”。引起“地包天”的病因很多,大致可分为以下几种:1.家族遗传的因素,一般在其父母或祖父母中有反(牙合) As we all know, the occlusion of the teeth is about 1/3 of the crown of the lower front teeth. If this is the case, the lower anterior teeth cover the crown of the upper anterior teeth, medically referred to as the anterior teeth (Occlusals), commonly known as “overcrowded” or “lower teeth.” Aroused “to the sky,” the cause of many, can be broadly divided into the following categories: 1. Family genetic factors, usually in their parents or grandparents have anti (occlusal)