牙齿在口腔内的牙床(牙槽骨)上,内外交错不能整齐地排列,就像人们的队列一样,有些人被挤出了队外,这就叫牙列拥挤。牙列拥挤是怎样造成的呢?原因大体有以下几方面:一是遗传因素。无论是个别牙错位,还是多数牙拥挤,都与遗传有关。二是替牙期障碍。如乳牙早失、乳牙 Teeth in the mouth of the gums (alveolar bone), internal and external staggered can not be neatly arranged, just like people's queue, some people were squeezed out of the team, which called crowded crows. Dental crowding is caused by what? The reasons are generally the following aspects: First, genetic factors. Whether it is individual tooth dislocation, or most crowded, are related to the genetic. Second, for the period of obstacle. Such as premature loss of primary teeth, deciduous teeth