Children have a certain time, position and order of tooth replacement, and the time of tooth replacement in young children is about 6-12 years old. The replacement of teeth in young children is the replacement of milk teeth by permanent teeth, and the replacement of teeth follows the physiological pattern of eruption in a symmetrical manner from front to back, from bottom to top. Usually, children start to change their teeth when they are about 6 years old. For example, at the age of 6, the first tooth, the mesial incisor, is replaced, and the first molar is replaced at the same time. The lateral incisors will be replaced at the age of 8-9 years. At the age of 11~12 years the replacement of the cuspids will take place and at the age of 10~12 years the replacement of the 1st bicuspids and 2nd bicuspids will take place. At the age of 6 to 7, the first molar comes in, at the age of 12 to 13, the second molar comes in, and at the age of 17 to 21, the third molar, which is also known as the wisdom tooth, comes in. If a child does not have normal tooth replacement during these times, it is recommended to consult a pediatric dentist to determine the cause of the problem and treat the problem under the guidance of the doctor. Meanwhile, during the period of tooth replacement, children need to pay attention to oral hygiene, avoid eating too hard and sugary food, which is not conducive to the growth of teeth.