When the old teeth are not lost and new teeth grow first, if the old teeth that should have been lost are extracted in time at the dentist, the newly grown permanent teeth will return to their correct position as the child grows up. During the process of tooth replacement in children, the roots of the teeth are gradually resorbed, resulting in the loosening and loss of the baby teeth, followed by the growth of permanent teeth. But nowadays, many children eat too fine food and the roots cannot be absorbed smoothly, so the new permanent teeth can only be squeezed out from the side, so the situation of double-row teeth appears. If the unerupted milk teeth are extracted in time at the dentist, even if the new permanent teeth are slightly crooked in position, the new teeth will gradually return to their normal position as the jawbone develops and is stimulated to chew, and enough space is vacated. Many of today’s oral problems in children, such as new teeth before the milk teeth recede, wisdom teeth can not grow smoothly in adulthood and other problems, are related to too fine food and insufficient chewing, so parents should pay attention to the children’s diet with adequate intake of coarse grains and fiber, and enhance the diversity of food.