Soreness and swelling after root canal treatment is considered to be a normal reaction or periodontal pathology may occur. 1. Normal reaction: some patients may experience soreness and swelling after root canal treatment, which is mainly related to individual sensitivity, and the filling material may irritate the surrounding teeth during the treatment process, so this symptom may occur, and it will be gradually recovered with the passage of time. 2. Periodontal lesions: patients with symptoms of acidity and swelling are considered to have a certain relationship with periodontal lesions, if there is periodontitis, periodontal abscess and other problems may lead to increased tooth sensitivity, this symptom. Usually, if the symptoms of dental acidity and swelling occur repeatedly, it is recommended to actively consult a doctor for examination and treatment.