Wisdom tooth pericoronitis is an inflammation of the soft tissue surrounding the crown of the third molar when eruption is incomplete or obstructed. Clinically, pericoronitis is more common in mandibular wisdom teeth, while pericoronitis in maxillary third molars is less frequent and has less clinical symptoms, fewer complications, and is relatively simple to treat. The main cause of this disease is due to the influence of anatomical factors in the eruption period of the third molar, clinically the most common partial eruption of vertical obstruction and proximity to the middle inclined obstruction, is also the most common complication of pericoronitis teeth, eruption of incomplete tooth position is mostly below the plane of the second molar, or even if flush with the coincidence plane, but its distal free gingival flap all or part of the surface of the obstructed tooth, and the crown between the formation of deep and narrow blind pocket. The self-cleaning effect is poor, and the food residues and bacteria hidden in the blind pocket are difficult to be removed, and the humidity and temperature in the blind pocket are very suitable for the growth and reproduction of bacteria. Under the action of pathogenic factors, such as chewing pressure and wisdom tooth eruption force, bite to the tooth, systemic and respiratory infections, fatigue, menstruation, systemic immunity decline, etc., it is very easy to cause acute attacks of pericoronitis. Local treatment is mainly to use 3% hydrogen peroxide + saline to rinse the gum pocket alternately; in addition, oral metronidazole can be given, and in severe cases, fluid infusion is required. If the tooth is misplaced, biting the cheek, etc., it should be extracted promptly.