Orthodontic correction is usually possible after root canal treatment. Orthodontic correction is usually possible after root canal treatment due to nerve necrosis caused by dental caries, but with normal periodontal tissues. The most basic cause of tooth movement caused by orthodontic correction in general is the stability of the internal environment of the periodontium; therefore, if the periodontium is normal, orthodontic correction can be performed without periodontal inflammation and alveolar bone resorption. In general, when the periodontium is damaged, normal periodontal treatment is required, and orthodontic correction can usually be performed after controlling the inflammation in the resting phase. If the alveolar bone resorption is more than 1/2, or even only 1/3, attention should be paid during orthodontic correction, which may lead to loosening and loss of teeth in the process of moving teeth. Therefore, patients need to do orthodontic correction under the guidance of professional doctors according to their own situation.