The main hazards of blocked teeth are as follows: 1. Recurrent pericoronitis: A blind pocket is formed between the soft tissue around the crown of the blocked wisdom tooth and the tooth, causing the accumulation of food and bacteria, and when resistance decreases, pericoronitis occurs. The general anti-inflammatory treatment treats the symptoms but not the root cause, so pericoronitis can recur. It often manifests as painful redness and swelling of the pericoronal tissue, which affects chewing, swallowing, and is often accompanied by difficulty in opening the mouth and fever, swollen Limba nodes and other systemic symptoms. If the inflammation is not controlled in time, it can also spread to the peri-maxillary and neck, forming inter-tissue infection, osteomyelitis of jaw, and even serious systemic complications such as sepsis and pericarditis can occur. 2.Caries: food residue can easily accumulate between the wisdom teeth and the second molar, and it is not easy to clean, so it is easy to form caries of wisdom teeth and second molar and pain occurs. 3, cause trigeminal neuralgia: there is evidence that some obstructed wisdom teeth are the foci of some trigeminal neuralgia. 4.Irregularity of teeth: the propulsion of wisdom teeth eruption movement is often one of the main causes of tooth crowding and irregular alignment. 5. Resorption of neighboring teeth and supporting tissues: When the eruption process of blocked wisdom teeth is obstructed in the second molar, it will trigger the gradual resorption of the root of the second molar, and in severe cases, the root of the distal middle of the mandibular second molar can be completely resorbed, resulting in loosening of the second molar and pain. Chronic periodontitis occurs between the wisdom teeth and the second molars, which can also cause inflammatory resorption of the alveolar bone and make the second molars repeatedly swollen and painful. 6, mandibular joint dysfunction: the obstruction of mandibular wisdom teeth is also one of the causes of mandibular disorder. The main clinical manifestations are popping, pain and abnormal jaw movement of the temporomandibular joint, pain of the chewing muscles and other symptoms. 7.Cystic lesions around wisdom teeth: Odontogenic cystic lesions in the jaws tend to occur in unerupted ambulant teeth, and mandibular obstructed wisdom teeth are one of the main sites of prevalence. 8. Pre-cancerous lesions of oral mucosa: The gingiva and buccal mucosa of obstructed and misplaced wisdom teeth may suffer from ulceration, erosion, abnormal tissue proliferation and white spots due to long-term mechanical stimulation or repeated biting of the crown edge. Such long-term trauma repair and re-traumatization process will affect the normal keratinization of oral mucosal epithelium and precancerous lesions will occur, which will induce oral mucosal carcinoma.