Gingival bulging after root canal treatment of a tooth may be caused by residual pulpal tissue, biological or mechanical irritation in the apical area, and the treatment modalities are to remove the sealing agent or filling in the root canal, reprepare the root canal, disinfect the root canal, and fill the root canal, as described below. If the tooth is swollen after root canal treatment, the root canal sealer or filling should be removed, and the infected material should be removed from the root canal by mechanical and chemical measures. If there is exudate in the root canal after extensive rinsing, the root canal should be opened, and if there is no exudate in the root canal, the canal can be resealed and disinfected, and then routinely filled. If superpreparation of the root canal is present, an apical barrier can be used to close the apical foramen. If the root canal lesion is recurrent, apical surgery can be performed to remove extraapical infection. It is recommended to go to the hospital in time to receive regular treatment as soon as possible.