When children’s new teeth grow out and the old ones don’t fall out, it is often referred to as retained milk teeth in the clinic. If children’s new teeth do not appear obvious deviation, and the milk teeth have been loosened, there is no need for special treatment, if the direction of the new teeth is shifted, or the tendency of infection around the teeth, it is necessary to remove the milk teeth in a timely manner. Retained milk teeth are usually caused by new tooth eruption obstacles, abnormal root resorption of milk teeth, or other factors. If a child has retained milk teeth, the measures to be taken need to be analyzed on a case-by-case basis: 1. If there is no inflammatory infection around the baby tooth, and the baby tooth has loosened and the new tooth is in a normal position, there is no need for special treatment and the baby tooth will fall out on its own. 2. If the direction of eruption of the new teeth is shifted, which affects the function and appearance of the teeth, or if there is inflammatory infection of the unerupted milk teeth, extraction of the milk teeth is necessary. 3. Orthodontic correction can be performed when the erupted new teeth have occlusal problems. Regarding the treatment of retained milk teeth, parents are advised to take their children to the doctor for relevant examinations and choose the appropriate plan.