It is important to take children to the hospital if their permanent teeth are growing behind their primary teeth. If the roots of the baby teeth are very long, the baby teeth may need to be extracted under local anesthesia to make room for the permanent teeth to slowly return to their normal position. In this case, it is recommended to start at home first by giving children more nuts, fiber, bones, corn on the cob and other foods from an early age, as they are more conducive to tooth replacement. In the case of permanent teeth coming in and milk teeth not falling out, the milk teeth have not fallen out after the permanent teeth have come in because the children are now eating too fine and fine food and the milk teeth have not been well stimulated and the roots have not been absorbed.