1.Cavity If wisdom tooth decay, except for the simple decay on the occlusal surface which is not deep enough to be filled, those wisdom tooth decay on the adjacent surface may not necessarily receive good results even after treatment, except for the need for good treatment techniques; the decay in this case is often more deeply damaged, and some even need root canal treatment, and it is always recommended to be extracted to eliminate future problems. 2. Invasion of neighboring teeth Since wisdom teeth destroy neighboring teeth slowly, patients usually do not know it themselves, and it is not always possible to accurately diagnose it during clinical examination, and it can only be diagnosed by taking dental X-ray. The eruption space of wisdom teeth is usually insufficient and will be on top of the penultimate molars, thus causing the second molars to be difficult to clean and even partial tooth resorption, resulting in discomfort or toothache. 3, insufficient space for eruption In the history of human evolution, due to the increasing fineness of food and smaller dental arches, the lack of space is very common, wisdom teeth belong to the fading state, in the process of eruption is easy to be limited by the lack of position and the occurrence of swelling and painful feeling of gums. 4, affect the oral hygiene Due to the lack of space, wisdom teeth are not easy to grow to a normal state, so it often causes difficulties in cleaning teeth, resulting in the occurrence of tooth decay. 5.No pair of teeth People have 1~4 wisdom teeth, and not everyone has all four wisdom teeth. Therefore, if there are no wisdom teeth opposite to each other, the over-eruption of wisdom teeth will often occur, which will affect the occlusal relationship between the upper and lower jaw teeth. 6, temporomandibular joint disorder syndrome Due to the abnormal occlusion of wisdom teeth leads to the abnormal operation of the temporomandibular joint and additional burden to form the temporomandibular joint disorder syndrome, the main clinical manifestations are localized soreness or pain, popping and movement disorders. The main clinical manifestations include localized soreness or pain, popping and movement disorders. The pain may be in the joint area or around the joint, and may be accompanied by pressure pain of varying severity; the soreness or pain of the joint area is especially obvious when chewing and opening the mouth; joint popping occurs when opening and closing the mouth, mouth opening is restricted, and the jaw is deflected when opening the mouth wide; in addition, it is accompanied by temporal pain, dizziness, tinnitus and other symptoms. 7, the formation of obstructive teeth This is the most undesirable situation, wisdom teeth are the last teeth to erupt in the tooth row, mostly erupted at the age of 18~25, due to insufficient eruption position, can lead to incomplete eruption of wisdom teeth and ectopic or obstructive, the crown is partially exposed outside the gums, partially covered by the gums. A narrow and deep blind pocket is formed between the gum and the tooth body, which is easy to accumulate food debris and bacteria, and is difficult to clean by general brushing and rinsing; in addition, the gum of the crown is easily damaged by chewing food and forms ulcers. When the systemic resistance decreases and bacterial virulence increases, it can cause pericoronal tissue inflammation – wisdom tooth pericoronitis, wisdom tooth pericoronitis is one of the very common oral diseases, but also wisdom tooth in the growth and development process of the biggest problem, because this wisdom tooth is the most difficult to deal with, many dentists will actively avoid this problem, in most cases the patient does not necessarily feel, so often in the doctor’s guidance also follow the ignored. The inflammation of acute pericoronitis of wisdom teeth affects the masticatory muscles and can cause varying degrees of mouth opening restriction, swallowing difficulties, and in severe cases, various complications can occur, forming subperiosteal abscesses, buccal-facial subcutaneous abscesses, gingival fistulas, skin fistulas, maxillofacial cellulitis, jaw osteomyelitis and even severe systemic infections.