The fact that the baby teeth do not fall out and the permanent teeth come in has a lot to do with the growth environment, eating habits and genetics. It is very common that the baby teeth did not fall out while the permanent teeth are growing out because children nowadays are more refined in nutrition and eat softer food, so the bones are not stimulated and do not develop well, which easily leads to the phenomenon. In this case, children must be encouraged to eat more hard things to exercise their teeth, which can promote bone development and allow permanent teeth to erupt normally. The milk teeth eat more hard things in order to promote root resorption and also promote bone development. When the bone development does not keep up with the width of the teeth, it can happen that the baby teeth are not lost and the permanent teeth have already erupted. Because the roots of the baby teeth are not resorbed, there is no place for them, so the permanent teeth will find another place to erupt. Therefore, it is important to encourage children to eat more hard things and chew more to exercise their teeth, which will help permanent teeth erupt.