The big teeth refers to the grinding teeth, and its pain is still more reasons, such as may be acute pulpitis, acute periapical inflammation, etc., if there are caries and other causes can also induce pain. 1. Acute pulpitis: acute pulpitis is one of the common causes of toothache. Due to dental tissue lesions affecting the pulp, the inflammatory reaction leads to pulp tissue enlargement and compression, and the hard tissue of the tooth body wraps it in, so there are often spontaneous, paroxysmal symptoms of severe toothache. 2. Acute apical periodontitis: acute bacterial infection occurs in the periapical tissues of the molars, and inflammatory exudate stimulates the periodontal membrane and local nerves, so there can be occlusal pain in the molars. When it develops into subperiosteal abscess, persistent and throbbing pain can also occur. 3. Dental caries: if there are cavities on the molars and deeper, it will also be stimulated by hot, cold, sour and sweet stimulation, which is easy to cause pain and discomfort. In addition, there are other causes can also cause teeth grinding pain, it is recommended that patients consult a doctor in time to confirm the diagnosis and give the correct treatment.