Tooth replacement is a normal physiological process. Normally, under the root of each baby tooth, there will be a germ corresponding to a permanent tooth. As a child grows older, the jawbone gradually develops, and the baby teeth complete their mission of chewing, and as they grow older, the baby teeth begin to replace. As the permanent tooth germ develops, the roots of the baby teeth are slowly absorbed and become shorter, at which point the baby teeth begin to fall out and the permanent teeth begin to grow in. Generally, children start to replace their first teeth at the age of 6-7 years, mostly starting with the incisors, while the first molar grows after the second molar. After that, the other teeth start to be replaced one by one. At the age of 12-13 years, all the baby teeth are replaced by permanent teeth, and after the age of 18 years, some of them will have their third molars. During the period of tooth replacement, parents should regularly observe the growth of children’s teeth and go to the hospital for treatment when abnormalities are found. In daily life, it is a good habit to brush the teeth in the morning and evening and rinse the mouth after meals to provide a good oral environment for the growth of teeth.