The main causes of night grinding are as follows: First, there are teeth misshapen, such as teeth misalignment, individual tooth cusps have early contact, uneven tooth wear will produce night grinding. Second, there are dental and mucosal diseases in the mouth, such as dental caries, periodontitis, pulpitis, periapical inflammation, wisdom teeth pericoronitis and oral mucosal ulcers, which will lead to swelling, pain and inflammatory factor exudation in the mouth, thus causing the occurrence of night grinding teeth. Third, before bedtime brushing is not clean, the tooth surface and a large number of food residues remain in the teeth, these will stimulate the taste buds and nerve cause night grinding. Fourth, before going to bed, eat too much or eat indigestible food led to the accumulation of food and abdominal distension caused by night grinding teeth. Fifth, picky eaters, partiality, nutritional imbalance, serious calcium deficiency will also have the phenomenon of night grinding teeth.