Lying down for breastfeeding may lead to dental eruption in infants and toddlers. Infants are artificially fed with bottles etc. when lying on their backs. Infants may try to wrap their lower lips around the bottle and develop bad habits of jaw protrusion, causing the lower dental arches to exceed the upper dental arches, resulting in the eruption of new upper and lower milk teeth, and inducing functional changes in the masticatory muscle groups. The long-term chewing stimulation of infants can cause excessive development of the mandibular alveolar bone, the maxillary alveolar bone is inhibited, forming a concave face, adults should promptly correct the feeding posture, avoid sleeping with a bottle, etc. After the completion of the eruption of the baby teeth at the age of 3.5 to 4 years old, you can wear movable orthodontic appliances to promote the upper front teeth lip to move, to inhibit the lower jaw forward, to break the encrustation.