Usually, children start to change their teeth at the age of 6 to 7 years old, and the timing of tooth replacement varies from tooth to tooth. Tooth replacement is a process in which the milk teeth fall out and the permanent teeth grow in. Under normal circumstances, there is a permanent tooth germ under the root of each milk tooth, and as the child grows and develops, the permanent teeth will also erupt one after another. Generally, a child’s teeth will begin to change at the age of 6-7 years old, when the child’s mesial incisors will begin to wobble until they fall out, followed by the permanent mesial incisors, and the child’s first molars will also erupt. Over time, the rest of the child’s teeth will be replaced, usually the lateral incisors at 8-9 years old, the 1st bicuspids at around 10 years old, the single cuspids at around 11 years old, and the 2nd bicuspids at 12 years old. At the same time, children will grow their 2nd molar after the 1st molar at the age of 12~14 years old until the 3rd molar at the age of 18 years old, but some people do not have the 3rd molar. Parents are advised to pay more attention to their children’s tooth replacement, and to seek prompt medical treatment if any abnormalities occur.