Gingival bulging after root canal treatment may be due to imperfect root canal treatment and periapical inflammation. At present, it is necessary to perfect the root canal treatment and carry out general treatment, drug treatment, surgical treatment and so on. 1. Root canal treatment is not perfect: after root canal treatment, it needs to be filled with medication and then sealed in a timely manner. If all the steps are not completed at present, the trauma may be irritated by external factors or food, which may lead to bulging of the gums. Currently need to complete the root canal treatment as soon as possible, and pay attention to oral hygiene. 2. Periapical inflammation: mainly related to inflammation after root canal treatment, repeated inflammatory stimulation will form periapical inflammation, resulting in pain at the root of the gums. If it lasts for a long time, it is easy to form an apical abscess, which will cause the gum bulge. After diagnosis, cephalosporin and metronidazole should be taken orally as prescribed by the doctor to reduce inflammation, and if an abscess is formed, it needs to be punctured and drained, and at the same time, root canal retreatment should be carried out in time. 3. Periodontal abscess: If the root canal treatment, do not pay attention to oral hygiene or due to long-term medication, affecting the periodontal tissues, easy to cause periodontal abscess, which leads to gingival bulging. At present, hydrogen peroxide can be used for rinsing, with disinfection, deodorization, but also can assist in the treatment of mild bleeding, if necessary, local incision and drainage. For patients who have undergone root canal treatment need to go to the hospital regularly for review, the doctor will take into account the patient’s recovery and some adverse reactions to choose the best treatment.