The permanent incisor will assume normal position and it is not necessary to extract the mobile primary incisor if there is enough room for the permanent incisor . delayed eruption of permanent teeth 一般来说，乳齿会因为牙根收缩而变得松动，跟着自然脱落，这是正常现象，不会影响恒齿的生长，所以不一定要拔掉松动的乳齿。
