Mandibular third molars (referred to as wisdom teeth) are most likely to become obstructed and cause recurrent episodes of pericoronitis. The indications for extraction of mandibular obstructive wisdom teeth are quite broad, because early extraction of obstructive wisdom teeth can prevent many of the problems caused by them from a preventive point of view. Indications for wisdom tooth extraction: 1. When the mandibular wisdom teeth are proximally and anteriorly inclined, the loss of bone in the distal middle of the mandibular second molar, coupled with the fact that the distal middle surface is not easy to clean, is prone to inflammation, and should be extracted in order to prevent periodontal destruction of the second molar. 2.When the wisdom tooth itself and the distal mesial surface of the second molar are decayed, the wisdom tooth can be extracted and then the decay of the second molar can be treated. 3.When the wisdom tooth can only partially erupt, the occlusal surface of the tooth is often covered by soft tissue, and the bacteria can easily breed, so that pericoronitis can occur repeatedly, and the wisdom tooth should be extracted at this time. 4.The pressure of wisdom teeth can cause root resorption of the second molar. Early removal of wisdom teeth can prevent root resorption of the second molar and help to preserve the second molar. 5.In order to prevent the occurrence of odontogenic cysts and tumors, the obstructed wisdom teeth can be removed prophylactically. 6.When wisdom teeth are completely buried in the jawbone, they can cause unexplained pain, and can be removed to prevent the occurrence of pain. 7.When it is suspected that the wisdom teeth may cause temporomandibular joint disorder, the wisdom teeth can be removed.