There are several possibilities for pulpitis without tooth decay. The first is caused by periodontal disease. When periodontal disease occurs, a wider gap will be formed between the periodontium and the teeth, which is prone to bacterial infection, and the bacterial infection from the periodontium can be involved in the apical part of the tooth, and from the root canal of the apical part of the root canal to affect the tooth nerve, and then it will be prone to retrograde pulpitis, which needs to be treated at the same time for periodontal disease, and also needs to be treated for endodontic disease. The second type of endodontitis is not caused by tooth decay, but may be caused by a tooth being jarred or having been hit by an external force. In this case, it is also necessary to treat the pulp in a timely manner, usually by choosing to do a root canal treatment of the tooth, removing the nerve and doing a filling on the surface of the tooth, to avoid the recurrence of pain.