Children’s molar teeth usually start to change around 9~10 years old. Children’s teeth are divided into milk teeth and permanent teeth, generally speaking, children start to appear around 6 years old, the order of tooth replacement for the first incisors, then lateral incisors, and finally molar teeth, most of the time in the replacement of molar teeth at around 9~10 years old, of course, if the child has vitamin D insufficiency, calcium deficiency, or other calcium and phosphorus metabolism disordered disease, the phenomenon of delayed tooth replacement may occur. During the period of tooth replacement, pay attention to oral hygiene, rinse the mouth frequently, avoid eating hard food, eat less sweets, try not to drink carbonated beverages, eat more vitamin C-rich vegetables and fruits, and eat more calcium-rich food to promote the normal growth of teeth.