1.The mandibular blocked wisdom tooth repeatedly causes pericoronitis; 2.The mandibular blocked wisdom tooth itself has caries, or causes caries and pain in one of the front molar (second molar); 3.The wisdom tooth and one of the front molar (second molar) have food embedment between them; 4.It has caused odontogenic cyst or tumor; 5.It is necessary to cooperate with orthodontic treatment; 6.The blocked wisdom tooth that causes temporomandibular joint disorder.