The common causes of teeth grinding in 3-year-old babies are: i. Intestinal parasitic diseases, especially intestinal ascariasis. Second, diseases of the gastrointestinal tract, oral diseases. Third, before going to bed to the child to eat indigestible food, so that after the baby sleep, are likely to stimulate the corresponding parts of the brain, through the nerve caused by the continuous contraction of the corner of the mouth muscles. Fourth, diseases of the nervous system, such as psychomotor epilepsy, hysteria, etc. V. Mental factors such as emotional excitement, overexertion, or emotional stress in children during the day. It is important to identify the cause and target the treatment.