Periapical abscess and periodontal abscess differential points: 1, the source of infection is inconsistent: periapical abscess and periodontal abscess as inflammation, the source of infection is not the same, the source of infection of periapical abscess is mainly the infected root canals, secondary to pulpitis or deep caries development, periodontal abscess is mainly secondary to periodontal pockets in the periodontium itself; 2, the dental situation is not the same: usually periapical abscess of the teeth, the teeth are missing, because it is from the development of caries, and periodontal abscess is usually intact; 3, the extent of abscess is inconsistent: the extent of abscess is usually lost, but the teeth of periodontal abscess is usually intact. Because of the development of caries, the pulp usually loses its vitality, while the teeth of periodontal abscess are usually intact; 3, inconsistency in the scope of abscess: the periapical abscess is usually larger in area and relatively confined to the apical part of the root, and the periapical abscess is relatively confined to the scope of the periodontal abscess and confined to the deep periodontal pockets; 4, inconsistency in destruction of the alveolar bone in the apical part: the destruction of alveolar bone of apical abscess is mainly confined to the apical part, and the destruction is mainly confined to the apical part, and the destruction is mainly confined to the periodontal pocket itself. Destruction of the alveolar bone in apical abscess is mainly confined to the apical part of the root, there is a relatively obvious dark shadow, but this is the case of destruction of a long time, periodontal abscess is usually accompanied by alveolar bone resorption, apical alveolar bone is in good condition, but the alveolar bone of the periodontium may appear horizontal or vertical resorption.