Because tooth replacement is a normal physiological process, children aged six or seven will start to change their teeth, and patients are advised to maintain good oral hygiene in their daily life. Then it can help the healthy growth of teeth. Six or seven year old children’s jawbone will gradually develop and grow, so the milk teeth will complete the role of chewing, with age, milk teeth will begin to fall out, the roots will be absorbed, permanent teeth will begin to grow gradually, this is a normal physiological process, generally 6 ~ 7 years old will begin to lose teeth, 12 ~ 13 years old milk teeth will be replaced by all the permanent teeth. It is recommended that parents should regularly observe the growth of the patient’s teeth and maintain oral hygiene, and go to the hospital for examination if abnormalities are found to avoid aggravation of the condition.