Teeth should not be extracted indiscriminately because if one tooth in a row is extracted, the whole row is prone to loosening. But there are some situations where not pulling out a tooth can bring more hidden health risks. Therefore, if you encounter the following nine cases, it is best to choose to extract the teeth, that is more conducive to health. 1.The overdue shedding of milk teeth, affecting the eruption of permanent teeth or milk teeth root tip exposure leading to ulcerative gingivitis. 2, crown caries is more serious, has been unable to repair, while the root of the tooth and lesions, not suitable for dental crown or overdenture. 3.Severe periapical lesions that cannot be cured by root canal treatment or apicoectomy. 4.Severe periodontal disease, resulting in frequent overflow of pus from the gum pockets, destruction and resorption of alveolar bone, loosening of the teeth by more than 3 degrees, loss of masticatory function, and treatment is ineffective. 5, no opposite teeth, misaligned teeth and multiple teeth, no biting and chewing function, and often cause tooth plugging, bite wound mucosa or affect the denture repair; or individual teeth are normal, but affect the denture repair and orthodontic needs must be removed. 6, abnormal position, can not erupt and repeated inflammation of the blocked teeth. Induced caries of neighboring teeth and prevent its filling treatment or cause the root resorption of neighboring teeth tilting the blocked teeth should be extracted as soon as possible. Causing maxillary sinusitis, osteomyelitis of the jawbone or repeated secondary infection of the maxillofacial space of the pathogenic teeth. 7, due to traumatic injuries caused by tooth splitting or fracture to the neck of the tooth below, can not be treated and repaired; or is located in the fracture line of the teeth, affecting the healing of the fracture need to be extracted. 8, due to osteonecrosis of the jaw bone, cysts or benign masses so that the teeth can not be retained; or malignant tumors in the radiation therapy before the radiation area of the diseased teeth, in order to prevent radiation therapy is easy to cause osteomyelitis of the jaw bone. 9, can induce systemic diseases, such as rheumatoid arthritis, rheumatic heart disease, endocarditis, nephritis and other diseases of the focal tooth. Common focal teeth are pericoronitis, inflammatory periodontal disease, alveolar abscess, etc., which should be considered for extraction if not cured.