New teeth that have not fallen out are a kind of retained milk teeth, which can lead to interlaced permanent teeth and poorly developed and uneven new teeth, and require timely extraction of milk teeth and, if necessary, orthodontic treatment after corresponding evaluation. The treatment of baby’s retained milk teeth can be divided into two cases, one is that the milk teeth are neatly arranged in the teeth, not affecting other teeth, and can play a normal chewing function, so they can be retained and continue to use; the other case is that the position and direction of the milk teeth are abnormal, and even cannot erupt, which will affect the baby’s jaw and facial development and oral function, such children need to go to a professional dental clinic to remove the retained milk teeth. After the removal, the new teeth may return to their normal position without the resistance barrier. If they do not return to their normal position, the teeth can be realigned through orthodontics, but this process is painful and not recommended for babies unless necessary. In addition to the treatment of baby’s retained milk teeth, the diet can increase the number of chewing food to stimulate the resorption of milk teeth roots, and the care of baby’s teeth should be strengthened in general, starting from oral cleaning, daily diet and the development of good brushing habits to take care of baby’s dental health.