Acute periapical pus drainage pathways, there are three main drainage pathways for acute periapical inflammation in clinical practice: 1, through the bone marrow cavity through the periosteum to the submucosa or skin, this type of drainage pathway is typical of the natural healing process, this drainage pathway is more complex, often accompanied by the presence of peri-maxillary cellulitis, the direction and location of the abscess drainage is closely related to the anatomical structure of the root tip, it can be through the periosteum to reach the submucosa or skin submucosa, through the periosteum through the skin, or through the maxillary sinus and through the mucosa of the nasal cavity in four directions of pus drainage; 2, through the apical foramen, through the root canal, and then the open defect of the crown side for pus drainage, this drainage pathway is mostly seen in those with thick apical foramen and open root canal, also in the clinical appearance of periapical inflammation, the early opening of the pulp drainage to establish the pathway, thus reducing the damage to the periapical tissue; 3. Drainage of pus through the periodontal membrane from the gingival sulcus or within the periodontium, this route is mostly seen in patients with periodontal disease. In addition, children are often drained through this route due to the loose periodontal tissue.