If a child has a bag on the gum, it is usually due to severe dental caries that causes pulp tissue lesion and eventually inflammation in the periapical region of the tooth, which is clinically manifested as biting pain in the affected tooth, swelling and pain in the gum at the periapical region, fistula and exudation or pus, and the child should be brought to the hospital in time. If the tooth defect is not particularly serious, endodontic treatment can be performed on the affected tooth to remove the decayed tooth tissue, open the pulp and drainage, and then remove the decayed pulp and the infected material in the root canal through root canal preparation so that the inflammation can be drained through the root canal opening, and seal the medicine in the root canal to reduce the inflammation. After the symptoms disappear, the root canal can be filled with a special filling material for baby teeth to isolate the external stimulus, and then the affected tooth can be restored or filled to restore the shape of the tooth and continue to perform chewing functions. If the child’s baby tooth has been severely damaged, it should not be retained, and the tooth should be removed under local anesthesia after the acute inflammation has resolved.