Clinical features and treatment measures of acute purulent pericoronitis: Inflammation of the soft tissues around the crown of the wisdom tooth (third molar) when eruption is incomplete or obstructed, which develops and aggravates to form an abscess when not treated in a timely or appropriate manner, mostly in the lower jaw. Clinical manifestations: local swelling and discomfort, with spontaneous throbbing pain and radiation to the auriculotemporal region. Systemic symptoms vary in severity and may include fever, chills, headache, loss of appetite, and elevated total white blood cell count. On examination, the lower part of the face is swollen with restricted mouth opening. The third molar eruption is incomplete or obstructed; the pericoronal soft tissue is red, swollen, eroded and painful to touch, and there is purulent discharge in the blind pocket; the inflammation may spread to the pharynx and tonsils; the ipsilateral submandibular lymph nodes are enlarged and painful to touch. The pericoronal abscess can spread locally to form a subperiosteal abscess in the posterior molar area, and there are several ways of spreading: (1) outward penetration can form a buccal gingival fistula above the submandibular appendage of the buccal muscle; if it is below the submandibular appendage of the buccal muscle, it can form a buccal fistula. Severe cases can lead to buccal interstitial infection. (2) Posteriorly spread along the lateral aspect of the mandibular ascending branch, which can lead to occlusal interstitial infection and marginal osteomyelitis. (3) Posteriorly along the medial aspect of the ascending branch of the mandible can spread to lead to infection of the pterygomandibular space and parapharyngeal space, or periportal abscess. (4) Downwardly, it can lead to abscess of the submandibular space and cellulitis of the floor of the mouth. Principles of treatment: Systemic and local are both important. Antibiotics should be applied systemically, and the necessary symptomatic and supportive treatment should be considered for those with severe systemic symptoms. Local area should be immediately incised and drained, and repeatedly flushed with 1 to 3% H2O2 and saline; maintain oral hygiene and give mouthwash. After the acute inflammation is controlled, the obstructed teeth should be extracted or gingival flap removal should be performed in a timely manner, and fistula scraping should be performed at the same time for those with buccal fistula.