很多年轻的父母认为孩子的乳牙总是要被恒牙代替的，所以并不在意对孩子乳牙的保护，其实乳牙发育不良，对恒牙也会造成很大的影响。一般婴儿自六七个月大时开始长牙，到两岁半左右长齐全部20颗乳牙。但也有少数婴儿较早（4个月）或较晚（周岁）开始长牙，这与婴儿本身体质发育 Many young parents think that their baby's deciduous teeth are always replaced by permanent teeth, so they do not care about the protection of the baby's deciduous teeth. In fact, the development of deciduous teeth can have a great impact on the permanent teeth. The average baby begins to teeth long after six or seven months of age and grows all 20 teeth at about two and a half years old. However, there are also a few babies who have started tooth decay earlier (4 months) or later (years old), which is related to the baby's constitutional development