Periodontal-endodontic lesions are periodontal and endodontic lesions that are connected, and depending on the cause, there are periodontal-endodontic lesions of pulpal origin and periodontal-endodontic lesions of periodontal origin. Periodontal-endodontic lesions of pulpal origin are caused by caries on the teeth or problems in the dentition that lead to inflammation of the pulp, inflammation of the root apex, and inflammation of the root apex that drains along the periodontal tissues, leading to periodontal destruction, and clinically, it is found that deep pockets appear in the periodontium or abscesses appear on the top of the gingiva, which may occur. Another is the periodontal cause of periodontal pulp joint lesions, the cause is more serious periodontitis, deep periodontal pockets, periodontal pockets inside the bacteria will be along the apical foramen or root canal side branch, resulting in inflammation of the pulp, the patient’s pulp will also appear necrosis, the pulp is not completely necrotic can also appear in the pulp inflammation, according to the degree of periodontal damage to decide whether to stay or extraction. Periodontal lesion destruction is not particularly serious, just narrow relatively small range of destruction, you can through periodontal treatment at the same time endodontic treatment, to see if you can try to retain the teeth; periodontal destruction is very serious, the teeth are also very loose, recurrent inflammation, lesions are relatively old, the teeth need to be extracted.