If the tooth is painful when it touches hot or cold, the tooth may have deep and large decay or pulpitis. In this case, endodontic treatment should be performed, and if pulpitis has developed, root canal treatment should be done to remove the infected nerve to solve the pain problem. If the pain is irritating due to a deep cavity, the decayed tissue will be removed, a layer of calcium hydroxide will be placed at the bottom of the cavity, and an indirect capping procedure will be performed followed by a conventional resin filling. Painful hot and cold teeth may also occur in patients with chronic periodontitis, which has varying degrees of alveolar bone resorption and root exposure. Once the roots of the teeth are exposed in the mouth, they will become sensitive to external hot and cold stimuli and even cause pain. For such patients, systematic periodontal treatment should be done, which mainly includes ultrasonic scaling, periodontal scraping and root planing. If the symptoms of tooth sensitivity are very serious, desensitization can be carried out using desensitizing toothpaste. If desensitization with toothpaste is not effective, laser desensitization or fluoride desensitization can be used for desensitization treatment.