Tooth replacement at the age of five and a half is not too fast, the development of the dental embryo and the development of the body are two mechanisms that do not correlate. The reason for premature tooth replacement in children is that most of the teeth are decayed or missing, and the loss of chewing function will stimulate the premature development and eruption of permanent tooth germ, but it is different from the development of bone, and it does not even mean that the child is premature. If the child rarely uses his teeth and eats soft food, which produces little stimulation in the mouth, he may also have a late tooth replacement. Therefore, as long as there are permanent teeth in the alveolar bone, tooth replacement is only a matter of time, and parents do not have to worry too much about it, as long as the child eventually replaces the teeth, it is not related to the development of other parts of the body.