The increase in the gap between the teeth caused by periodontitis is a clinical symptom that is more common in the middle and late stages of periodontitis, which has a greater impact on the patient and is relatively difficult to deal with clinically. In this case, the premise is to control periodontitis, because if periodontitis is not controlled, there is no way to treat the gap between teeth, it will only get bigger and bigger, and for periodontitis, systematic periodontal treatment should be carried out, including supragingival scaling and subgingival scraping, root planing and so on. The periodontal plaque and calculus will be thoroughly cleaned and some medications can be considered to bring the periodontium to a healthier state. If the periodontitis is well controlled, then the gaps in the teeth can be treated at this time. Generally, orthodontic treatment can be considered to close these gaps as much as possible, so that the loosening of the teeth with food inclusions can be significantly relieved, but all this must be done when the periodontal inflammation is well controlled.