Root canal treatment is not necessary in most cases of periodontitis because it is not an indication for periodontitis. Root canal treatment is mainly for pulpitis and periapical periodontitis, which are treatments made for dental diseases; whereas the symptoms of periodontitis are loss of attachment of the entire gum, which eventually leads to gum recession, resorption of the alveolar bone, formation of loose teeth or even loss of the entire mouth, and the primary risk factor for periodontitis is loss of the entire mouth in adults. Root canal treatment is a treatment plan for a single tooth, and the treatment plan for periodontitis is a basic periodontal treatment, which usually includes scaling, or what we usually call supragingival scaling, but for periodontitis, scaling alone is not enough, but also needs to be accompanied by subgingival scaling, root planing, and periodontal surgery if necessary, to try to maintain our periodontal health, so that periodontitis can be controlled and not further developed.