孩子在六岁至十二岁时,恒牙将陆续替换原有的乳牙,医学上称这一时期为“替牙期”。因为这一时期乳牙和恒牙同时存在,也叫做“混合牙列阶段”。发育早一些的孩子“替牙期”出现的早,有的五岁就开始了。如果这一时期,乳牙尚未脱落,而附近又钻出了新牙,这就是所谓里外“双排牙”。 Children from six years old to twelve years old, permanent teeth will gradually replace the original deciduous teeth, medically referred to this period as “periodontal ”. Because of this period of deciduous teeth and permanent teeth exist, also called “mixed dentition stage ”. Early development of children “tooth period ” appeared early, some five years began. If during this period, deciduous teeth have not yet fallen off, but also drilled near the new teeth, which is the so-called inside and outside “double row teeth.”