Tooth nerve pain is usually caused by the following reasons: first, pulpitis caused by tooth decay, if tooth decay is stored in the mouth for a long time without treatment, it will cause bacteria to attack the tooth nerve and pulpitis will occur, which will cause severe tooth pain. Secondly, the tooth is fractured by trauma, in this case, the pain is similar to that of pulpitis, and root canal treatment is also needed. Third, periapical periodontitis, which is a further development of pulpitis, not only invades the nerve and even the periapical area, but also invades the alveolar bone, which may also cause neuralgia.