There is no fistula in the tooth, but the common fistula is usually located in the apical part of the tooth, that is, gingival fistula. Gingival fistula is a necrosis of the pulp of the tooth corresponding to the apical part of the tooth, it is developed from caries, the caries of the tooth further develops into pulpitis, the pulpitis further develops into periapicalitis, the periapicalitis breaks through the alveolar bone and forms a fistula in the gum, this indicates that the pulp has necrosis, but the tooth can still be considered for preservation. The fistula can be closed by pulpotomy and systematic root canal treatment. After the fistula is closed, the tooth can be protected by crown restoration and the tooth can serve the patient for a longer period of time instead of the whole tooth being necrotic.