Drinking milk while lying down may cause babies and young children to develop a circumcision. Baotian, also known as anterior anti-mandibular, refers to the orthodontics bite, the lower front teeth bite on the lip side of the upper front teeth, the coverage is negative, the fit type of front teeth basically no cutting function, is a dental malformation. Infants lying down for a long time to drink milk, due to chewing stimulation caused by excessive development of the mandibular alveolar bone, while the maxillary alveolar bone is inhibited, the formation of concave face, resulting in newly erupted upper and lower milk teeth in a geodesic, and may also induce chewing muscle groups to change function. It is recommended that adults should correct the poor milk drinking posture of infants and children in time, and avoid sleeping with a pacifier. If babies and young children have pericoronitis, it is necessary to wait until the completion of the eruption of milk teeth, and then wear movable orthodontic appliances for orthodontic treatment, movable orthodontic appliances can push the upper teeth lip forward, inhibit the lower jaw forward, improve the symptoms of pericoronitis. Bad habits such as lying down for a long time to drink milk, sticking out the tongue, sucking the finger and biting the upper lip are easy to lead to the circumcision, which should be corrected as soon as possible.