Gum swelling and pain may be caused by periodontitis or apical periodontitis, after appropriate periodontal treatment and root canal treatment, the gums can generally be about 3~7 days to reduce the swelling, as follows. 1. Periodontitis: periodontitis may appear in the advanced stage of development of periodontal abscess, causing symptoms of swollen gums, the need for thorough gingival cleaning and subgingival scraping to remove plaque and tartar, if the pus is formed, the surface of the gums fluctuating feeling, through the periodontal pockets or the surface of the gums drainage, to promote the swelling of the gums. 2. Apical periodontitis: acute purulent apical periodontitis to the development of subperiosteal or submucosal abscess stage, there can be swollen and painful gums, the need for endodontic treatment, in the pulp cavity open at the same time can be incised pus drainage, can reduce pain and eliminate swelling. There may be other causes of swollen and painful gums, it is recommended to go to the hospital in a timely manner, to clarify the cause of the disease and then targeted treatment.