First, why do we need to take X-rays for dental treatment? X-rays of teeth, also known as dental films, are an important tool in the process of dental diagnosis and treatment. They are used to discover the extent and scope of lesions before treatment, to guide treatment and determine the scope and depth of treatment, and to observe the efficacy of treatment after treatment. Through dental radiographs, the dentist can find out how extensive the decay is, whether the toothache is caused by inflammation of the pulpal nerve, apical inflammation or periodontal inflammation, whether the condition of the veneer is adequate, the amount of bone needed for dental implants, developmental malformations, certain tumors, etc. In addition, dental radiographs provide a good basis for patient-doctor communication. Therefore, it is necessary to take dental films during the consultation and treatment. Second, what kinds of dental films? At present, the following types of oral radiological examinations are commonly used in dental treatment: 1, dental films; 2, occlusal films; 3, lateral cephalometric films; 4, comprehensive tomography films (commonly known as large films); 5, cone beam CT (CBCT). Third, what is the threshold of radiation that may cause disease? May dental films cause harm to the body? 1.The average daily background radiation exposure of a normal person is 10μSv; (the dose unit is Sv “sievert”) 2.Long-distance flight is 6μSv; 3.The lowest dose known to have an effect on the carcinogenic rate is 100,000μSv (0.1Sv); 4.The safety threshold of radiologists is 20,000μ Sv/year; 5. X-ray chest radiation is 80μSv; 6. Chest CT radiation is 5,800μSv; 7. Dental X-ray is about 5-150μSv. 4. Can pregnant women and children take X-ray films? In certain dental treatment emergencies, pregnant women may have to take dental films before the baby is born. Untreated dental infections can pose a potential threat to the fetus. Since dental treatment is usually free and optional, it is not advisable for pregnant women to have dental films taken during the first trimester of pregnancy, as the fetus is more sensitive than normal. After the third trimester, if a pregnant woman must undergo x-rays, she should wear protective clothing – a lead suit or a “lead rubber apron” around her abdomen – to prevent radiation from harming her and her fetus. Under these conditions, the effect on the fetus is almost negligible. As long as the radiation is not a high dose to the abdomen or its vicinity, the mother-to-be should not worry too much. In addition, children are uniformly dressed in lead suits or skirts when dental films are taken. Children are developing at a high rate, with high gonadotropin secretion, and as a result, the bone marrow is often active and tender and vulnerable to X-ray radiation, so it is necessary to protect the rest of the body from receiving zero chance of scattered radiation.