There are two main reasons for bad breath caused by tooth decay: First, decay and deterioration of teeth caused by tooth decay itself. Secondly, food impaction caused by tooth decay. For decayed teeth with preservation value, filling treatment should be carried out on the basis of removing the decayed material. If the cavity is deep and does not involve the pulp, the pulp-protecting material should be placed at the bottom of the cavity and then filled. If the cavity involves the pulp, root canal treatment should be carried out under local anesthesia, and then the cavity should be filled. For teeth with no preservation value, such as blocked wisdom teeth, ectopic eruption of teeth, or teeth that need to be extracted due to orthodontic treatment of caries, local anesthesia can be extracted under the affected teeth.