Wisdom tooth is the third molar and has an important influence on the adjacent second molar. As most of the wisdom teeth are anteriorly inclined and obstructed, they are about 45 degree angle on the second molar, thus forming a crown angle, which is easy to embed food and lead to decay of the second molar and even pulpitis in the long run, even if it is not that serious, it will affect the life span of the second molar. Hazard 1, recurrent pericoronitis. A blind pocket is formed between the soft tissue around the crown of the blocked wisdom tooth and the tooth, which causes the accumulation of food and bacteria, and when the resistance decreases, pericoronitis is inevitable. The general anti-inflammatory treatment can treat the symptoms but not the root cause, so pericoronitis will recur. Hazard 2, tooth decay. It is easy to accumulate food residue between the wisdom tooth and the second molar in the wrong position, and it is not easy to clean, so it can form caries in several months, and directly destroy the tooth tissue. Hazard 3, pain. The blocked wisdom teeth often cannot establish normal occlusal relationship with the teeth of the opposite jaw, which can lead to the popping of temporomandibular joint, painful opening of mouth and night grinding for a long time, which has a great impact on the physical and mental health of young adults. The jawbone that holds the teeth continues to degenerate and become smaller, so wisdom teeth obstruction is the inevitable result. The removal of the blocked wisdom teeth does not have any adverse effects on the functions of chewing and speech, plus it is the most effective way to treat the blockage. Hazard 4, trigeminal neuralgia. There is evidence that some obstructed wisdom teeth are the foci of some trigeminal neuralgia.