Babies usually start teething at 4-10 months of age.
There are a total of 20 milk teeth, the eruption order is generally the lower jaw before the upper jaw, from front to back, in order of the lower middle incisors (6 months), upper middle incisors and upper lateral incisors (9 months), lower lateral incisors (12 months), upper and lower first molar (18 months), upper and lower single cusp (2 years old), upper and lower second molar (2 and a half years), most of them can come out by the age of 3 years, and if the time of eruption is >3 months, it is delayed teething.
There are a total of 28 or 32 permanent teeth. The first permanent teeth erupt around 6 years of age and come in at 12 years of age.
The healthy growth of baby teeth is usually related to the bones, but also to the levels of protein, calcium, phosphorus, fluoride, vitamins, and thyroid hormones, etc. Babies benefit from the growth of teeth by chewing food.