The pain after filling needs to find out the cause of the pain and treat it according to the cause. The common pain after filling is the stimulation of filling material to dental nerve after filling, in the process of removing the decayed tooth hard tissue, the tooth decay is deeper and close to the dental nerve, the material expansion after filling has certain pressure to the dental nerve, pain appears, usually twenty-four hours to relieve by itself, no need to deal with. If there is a small pulp hole not found during the drilling process, and the filling acts directly on the nerve of the tooth, there will be continuous pain, and this situation needs root canal treatment of the tooth to relieve. The pain after filling may also be caused by a high filling material and a high point in the biting process, in which case the tooth needs to be adjusted and treated. It may also be caused by gingivitis due to an overhang on the adjacent surface of the filling material, which requires prompt restoration of the tooth’s contoured adjacent points to improve the gum symptoms. Pain after filling may also be caused by the filling material and the opposing tooth being different metals, and the two metal elements forming micro-currents under the action of saliva as a medium, which needs to be changed to the same metal material filling, or to a non-metal type material filling. If the pain after filling is pulpitis, root canal treatment is needed. If it is a high bite, it needs to be adjusted in time, and the different metals should be changed to the same material filling.