In case of painful tooth decay, it depends on the extent of the decayed tissue and whether the pulp has been destroyed. If the decayed tissue has not destroyed the nerve and the pain is present, then a filling treatment should be performed after the soothing treatment. If the nerve has been destroyed, root canal treatment is needed, followed by filling treatment or restoration treatment. Tooth decay, also known as dental caries, is caused by bacteria acting on the tooth and destroying the tooth tissue to form a cavity. Once you get caries, you should do early diagnosis and early treatment, and do filling treatment in time when the early caries is very small, then you can control the caries and prevent it from developing. If the caries is not treated timely in the early stage, it will continue to damage the tooth and destroy the nerve of the tooth, which will form the pulpitis or periapical inflammation, and then the tooth will have obvious pain. Once the pulpitis or periapical inflammation is formed, it is not possible to do the filling treatment directly, but it is necessary to do the root canal treatment first and then the filling treatment. If the caries is in the state of deep caries, it will also cause some pain, because the decayed tissue is very close to the nerve at this time, so it should be treated with zinc oxide for pacification first, and then permanent filling treatment will be done after no spontaneous pain occurs during the pacification period.