Toothache to kill the nerve is good to judge according to the cause of the disease, such as dental caries (not involved in the pulp) do not need to kill the nerve, while pulpitis, apical periodontitis need. 1. Dental caries: the tooth is infected by dental bacteria and thus the dentin is damaged, and pain may occur when the dentin is damaged to the dentin. There is no need to kill the nerve without damaging the nerve, and it is recommended to remove the decayed tissues for filling treatment. 2. Pulpitis: Pulpitis means that the nerve is infected with inflammation, and the pain caused by pulpitis is very severe, and severe cases have difficulty eating and sleeping. Opening and draining the pulp and killing the nerve can relieve the pain, so it is generally recommended to kill the nerve for treatment of pulpitis. 3. Periapical periodontitis: pulpitis without timely treatment may develop into periapical periodontitis, the tooth produces a sense of floating, biting pain, etc., to cure periapical periodontitis also need to carry out root canal treatment. Toothache should be treated under the guidance of a doctor in a timely manner, and the nerve of the tooth can be preserved as much as possible.