The swollen gum bag after filling can be considered from the following aspects: First, because the filling has overhang to press the gum and stimulate the swelling of gum when filling, the swollen bag phenomenon slowly appears after filling. Second, the depth of the cavity is very close to the nerve when the filling is filled, which may lead to the nerve necrosis after the filling, thus the swelling is obvious and the gum appears pus. In the above two cases, it is recommended that the patient should go to the dentistry department of the regular hospital for follow-up examination as soon as possible, and X-ray can be taken to confirm whether it is caused by pulp necrosis. If it is due to pulpal necrosis, a new root canal will be needed to remove the necrotic nerve and the gum abscess will disappear naturally.