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换牙要换多少只
更新时间: 2020-11-04 00:00:00  

换牙要换乳牙20个,一般从六周岁开始换牙,20颗乳牙全部换掉的时间大约是半年到一年,这时孩子要注意饮食了。

换牙是乳牙脱落,恒牙长出的过程。在生长发育过程中,每个乳牙牙根的下方,有一个恒牙胚并逐渐发育长大,恒牙在萌生过程中,一方面压迫乳牙根与恒牙胚之间的牙槽骨,并通过破骨细胞的作用,使骨质吸收变薄,直至完全被吸收;另一方面直接压迫乳牙根,使乳牙根渐渐吸收,变得越来越短,直至完全消失。于是乳牙便开始脱落,恒牙逐渐长出。

关键词: 多少

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