The human body can have two sets of natural teeth, milk teeth and permanent teeth, throughout life, depending on when the teeth erupt. The eruption of the milk teeth begins in the 6th to 8th month of life and is completed by the end of the 2nd year of life. Permanent teeth usually begin to erupt around the age of 6 years, when milk teeth begin to fall out, and all milk teeth can be lost by 12 to 13 years of age. Permanent teeth stay with a person for the rest of his or her life until they are lost. Adults basically have permanent teeth in their mouths, and rarely retain milk teeth. Therefore, the teeth extracted in adults are permanent teeth, so no more teeth will grow after extraction, and only dental restoration can be done. After extraction, the missing teeth should be restored in time to avoid affecting the aesthetics and chewing function.