Gums keep hurting after filling may be caused by improper filling, intraoperative operation injuring the gums, periapical lesions and other reasons. 1. Improper filling: Because the edge of filling material is too long or filling body forms overhanging protrusion in the gingival margin, the gum tissue is compressed, so the gums keep hurting after filling. 2. Injury to the gums during the operation: Because the instruments hurt the gums and periodontal membrane during the filling process, or the acid etching agent overflows to the gums, which may lead to the occurrence of gingivitis, so the gums keep hurting after the filling. 3. Periapical lesions: due to pulp degeneration and necrosis, triggered by apical inflammation, periapical tissue destruction can penetrate the bone wall will cause the gums around the root tip of the swelling and pain, pressure and pain. Gums after filling has been painful situation, should be timely to the hospital, clear cause, follow the doctor’s instructions for treatment.