Sudden pain in the tooth one year after filling may be secondary caries, pulpitis, apical periodontitis and so on. 1. If there is a sudden pain of hot and cold stimulation without spontaneous pain one year after filling, it may be secondary caries. 2. One year after the filling, if the tooth suddenly appears hot and cold stimulation pain, spontaneous pain, night pain, radiating pain, then it may be secondary caries involving the pulp of the tooth. 3. One year after the filling if the tooth suddenly bite pain, gums bulging pus, etc., it may be periapical periodontitis. A year after the filling of the tooth suddenly pain may also have other pathological factors, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.