Root canal therapy 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, and is made for this type of dental disease. The symptoms of periodontitis are loss of gingival attachment, resulting in gum recession, resorption of alveolar bone, and eventually loosening and loss of teeth. The treatment of periodontitis is the basic periodontal treatment, which usually includes scaling, or what we usually call supragingival scaling, but for periodontitis, scaling is not enough, but also needs to be combined with subgingival scaling and root planing. These treatments can effectively remove plaque and calculus from the periodontium to achieve a healthier periodontium. If necessary, periodontal surgery is also needed to maintain the health of the periodontium and to keep it under control.