Tooth replacement is a process in which the baby teeth fall out and the permanent teeth come in. In the process of growth and development, there is a permanent tooth germ under the root of each milk tooth and gradually grows up. During the process of eruption, the permanent tooth presses the alveolar bone between the milk tooth root and the permanent tooth germ on the one hand, and through the action of osteoclasts, the bone is absorbed and thinned until it is completely absorbed; on the other hand, it presses the milk tooth root directly, so that the milk tooth root gradually absorbs and becomes shorter and shorter until it disappears completely. Then the baby teeth begin to fall out and the permanent teeth gradually grow in. The following precautions should be taken: 1. Let your child have more hard foods, such as apples, sugar cane, meat bones, fennel beans, dried groundnuts, and chew more; 2. Check often to see if there are new teeth coming in and the baby teeth are not falling out. During the period of tooth replacement, children should learn to floss to prevent tooth decay; 5, during the period of tooth replacement, they must brush their teeth carefully to maintain oral hygiene, do not drink carbonated beverages, and brush their teeth after eating sweets to prevent tooth decay; 6, during the period of tooth replacement, six-year-old teeth and newly erupted back teeth must be closed to prevent tooth decay; 7, if the teeth that have not been replaced are decayed, they should be treated as soon as possible to ensure normal eruption of permanent teeth; 8, after consuming dairy products, they must rinse their mouth with clean water, including milk teeth. Rinse your mouth with clean water after consuming milk products, including milk teeth, to prevent tooth decay.