After 12 years old to orthodontics”, this understanding is one-sided. There are a variety of dental malformations or abnormalities must be corrected before the age of 12, otherwise it will affect the facial aesthetics, oral health or later orthodontic effect, so parents should give their children timely orthodontic never hesitate! 1, individual teeth rebound, that is, individual incisors or two teeth rebound, extremely harmful. It may cause bite trauma that cannot be healed by permanent teeth, and the potential harm may lead to temporomandibular joint disorder. 2. Inversion, commonly known as “enamel”, means that the lower row of teeth wraps around the upper row of teeth. It seriously affects the beauty of the face, chewing function decreases, slow eating, aggravates the gastrointestinal burden, affects facial development deformity, and also affects the clarity of pronunciation. 3.Deviated jaw. Due to one side of the tooth decay, missing or unknown reasons, the jaw is skewed facial asymmetry, resulting in difficult to treat temporomandibular joint disorder, which seriously affects the child’s mental health and self-esteem. 4. Snoring or open-mouth breathing during sleep. Mostly due to nasal blockage, rhinitis or adenoid hypertrophy and other reasons caused by poor nasal breathing, causing open lips and teeth, high palate arch face narrowing, protrusion, long face shape, chin recession and back teeth can not bite together. 5.Serious big buck (violent) teeth. Severe protrusion of the upper front teeth, the mouth and lips are difficult to close, some children are afraid to smile and do not take the initiative to communicate with others, which greatly affects school and social life, and some children will become very low self-esteem. 6, jaw recession. Underdeveloped chin, small chin, commonly known as bird’s mouth. It affects facial aesthetics, and at the same time, because the upper jaw teeth are too narrowly aligned, it restricts the development of the lower jaw teeth, which also affects the function. 7. Post-operative cleft lip and palate. Not everything is fine after cleft lip and palate surgery, and stages of orthodontic treatment are needed to maximize the good appearance and physiological function. 8.Permanent teeth. Non-eruption or ambulatory obstruction. Partial eruption or complete failure of eruption of teeth, children’s front teeth are common. It can be improved by aiding eruption or traction. 9.Multiple teeth. Multiple teeth are mostly malocclusion, they occupy the position of normal teeth, resulting in misalignment or eruption disorder of normal teeth. 10, bad lip and tongue habits. Including biting the lower lip, sucking the lower lip, lower lip pocketing the upper lip, extending the tongue, spitting the tongue, licking the tongue, topping the tongue and other bad habits affect the occlusion.