The age at which children usually start to change their teeth is 6 to 8 years old. However, due to the fact that children nowadays are more well nourished, there may be a situation where they start to change their teeth at the age of four and a half years old, but at this time the child’s alveolar bone is not yet fully developed, so it is not normal. Children begin to change their teeth at the age of 6 to 8 years old, starting with the mesial incisors, the lateral incisors at the age of 8 to 9 years old, the premolars at the age of 10 to 12 years old, the second molar at the age of 12 to 13 years old, and finally the third molar, or wisdom teeth, which usually do not begin to come in until after the age of 17 years old. If four and a half years old began to change teeth generally do not need to worry too much, due to the alveolar bone is not fully developed at this time, there may be symptoms of tooth crowding, can be restored through the latter part of the orthodontic.