The toothache is not painful when it contains cold water, which means that the affected tooth is an acute pulpitis tooth, and it is a typical symptom of hot pain and cold relief. Acute pulpitis is mostly caused by dental caries and is an acute attack of pulp congestion or chronic inflammation, which is clinically manifested by severe pain in the tooth, which can be stimulated by hot or cold, and is aggravated by pain at night, and is radioactive, with headache and earache. This is because the metabolites of bacteria in the pulp cavity will expand when heated, increasing the pressure in the pulp and producing severe pain, and due to the principle of thermal expansion and cold contraction, cold stimulation can cause it to contract and reduce the pressure, temporarily relieving the pain symptoms. Therefore, most of the patients who come to the clinic are patients with acute pulpitis, and these affected teeth should be seen in a timely manner, and pulp drainage can immediately relieve the symptoms of pain, and root canal treatment is performed after the acute period.