When children reach the age of six or seven, they start to replace their baby teeth with permanent teeth. However, we often find that some children’s permanent teeth have already erupted, but the corresponding milk teeth have not fallen out, which is called “retained milk teeth”. Parents should take their children to the hospital and have them extracted as soon as possible so as not to affect the eruption of permanent teeth in their normal position. The main reason for the increasing number of retained milk teeth is the lack of necessary physiological stimulation of the teeth due to the excessive refinement of the child’s food, which affects the natural resorption of the roots of the milk teeth and delays their loss. Therefore, parents should let their children eat more chewy foods, such as celery and corn, so that their baby teeth receive good physiological stimulation and smooth tooth replacement.