Habitual teeth grinding during sleep or unconscious teeth grinding habit during wakefulness is called bruxism. The etiology of nocturnal teeth grinding is still unclear, and is currently believed to be related to mental, emotional, odontogenic, systemic, occupational, spontaneous and other factors. Analysis of the factors of teeth grinding: 1, mental factors oral cavity has the function of indicating tension, the patient’s fear, anger, hostility, resistance and other emotions, especially anxiety, if for some reason can not be expressed, trying to relieve the inner sense of melancholy by grinding the teeth, this kind of patient teeth contact time is long, and frequent. These mental factors may be one of the important factors in the etiology of teeth grinding disorder. 2, dental factors in nervous individuals, any dental interference may be a trigger factor for bruxism; bruxism patients’ dental factors are mostly orthodontics and orthodontics do not match, as well as lateral dentition when the non-working side of the early contact; and clinical methods of adjusting the teeth together have also successfully cured some of the bruxism. Dentition factor is an important factor in oral health, but whether it is the cause of bruxism is still controversial; the mismatch of occlusal relationship during the period of tooth replacement, resulting in disorders of masticatory muscle movement, spasm and contraction. 3.Central nervous mechanism at present, there is a trend to believe that teeth grinding is an involuntary subconscious action like sleepwalking, urination and nightmares, which is a symptom of partial arousal of the brain during sleep, and the central source of sleep disorders related to daytime emotions, triggered by internal or external, psychological or physiological sleep disturbing stimuli. 4, other systemic factors and parasite-related gastrointestinal dysfunction, children’s nutritional deficiencies, blood glucose and calcium concentrations, endocrine disorders, perverse reactions, etc. may become the pathogenesis of bruxism. In some cases, there are genetic factors. In addition, uric acidosis, hyperthyroidism, allergy, bladder stress, etc. may have a relationship with teeth grinding disorder. 5, occupational factors car drivers, athletes, demanding high precision work, such as clock work, have a tendency to occur grinding. The harm of teeth grinding: The most serious harm is the night clenching and nocturnal teeth grinding. Nocturnal teeth grinding is more common in children. Although night grinding will not feel any pain for a while, but in the long run, it can cause serious wear and tear of the dentition and neighboring surfaces of the teeth, as well as the complications of the above mentioned diseases, and persistent teeth grinding will lead to destruction of periodontal tissues, loosening or shifting of the teeth, recession of gums, and loss of alveolar bone. During the day we chew food also rubbing teeth, but very little damage to the teeth, this is because when chewing, the food between the upper and lower teeth is like a cushion, while there is sufficient saliva, so that the teeth slippery, so it is not easy to wear. In the meal looks like chewing for a long time, but most of the time is in the up and down movement, the real direct tooth contact has been studied only about 4 minutes. If you grind your teeth at night, the situation is very different, there is no food in the mouth, the secretion of the oral cavity is also reduced, the teeth do not get the necessary lubrication, and the formation of dry grinding, it is like pushing an empty mill. The wear and tear of the teeth is very large, the consequences are also quite serious, at this time the worn teeth often have different procedures of acidity or pain, and sometimes also cause temporomandibular joint dysfunction, due to the destruction of the form and function of the dental occlusal system. It can in turn cause abnormal masticatory muscle function, such as masticatory muscle hyperfunction, spasm, fatigue, and pain. Muscle contraction imbalance, abnormal dentition position, change of intermaxillary vertical height, and dislocation of disc positional relationship also directly affect the normal morphology and function of the temporomandibular joints, manifesting symptoms such as pain at the mandibular joints, joint popping, and restriction of mouth opening. The pain is oppressive and dull, and it is especially significant when getting up in the morning. Preventive measures: 1, during the day to keep the mouth in a healthy state of rest, that is, let the teeth to maintain the relaxation, preferably lips together, teeth away from each other; 2, hot compresses on the upper and lower jaws, can relax the bite muscles, but also reduce the chances of a headache; 3, teeth grinding and stress has the most to do with, so relaxation is the best way to do so; 4, to reduce the amount of caffeine and refined carbohydrates intake; 5, leniency to themselves, reduce stress. Learn relaxation methods, such as meditation or progressive relaxation warm baths, etc.; 6, can go to the dentist to make teeth grinding protection period to protect teeth and prevent wear and tear.