Tooth decayed a hole and pain in time to fill the tooth or do root canal treatment. 1. Filling: If the tooth has a cavity and is painful, if the pain is not obvious, no spontaneous pain, only hot and cold transient pain, you can use a dental drill to grind away the decayed material in the cavity, and the bottom of the cavity does not penetrate the pulp, you can use calcium hydroxide to fill the tooth with resin after cushioning. 2. Root canal treatment: if the pain of tooth decay is obvious, hot and cold pain, spontaneous pain, night pain, generally it has been infected to the pulp, or the pain is not obvious but the pulp has been leaked during the process of removing the decayed material with a dental drill, in this case, it is impossible to fill the tooth directly, and it is necessary to carry out the root canal treatment first and then fill the tooth or restore the whole crown. When a tooth has a cavity and is in pain, it is important to seek medical attention in a timely manner and under the guidance of the doctor for examination and treatment to avoid delays.