Dental radiography (taking X-rays) is a crucial diagnostic tool for dentists which usually cannot be omitted. But how significant is the radiation exposure from dental X-rays to the human body?
为什么看牙要拍片？
Teeth are like icebergs, with 60 percent of their structure hidden beneath the gums. Dentists need images of the whole structures to visualize cavities (dental caries), impacted teeth, periapical lesions, or jawbone conditions to formulate treatment plans and ensure smooth procedures.
1 Sv = 1000 mSv
1 mSv = 1000 μSv
Periapical Radiograph
Panoramic Radiograph
Cone-Beam Computed Tomography
三维重建颌骨，用于种植牙、复杂手术导航等。辐射≈5.00–652.00μSv，CBCT辐射剂量根据视野的大小及分辨率的不同差异较大，常规检查一般在100μSv左右。
拍一次根尖片≈吃二十根香蕉
Low doses of natural background radiation (from soil, air, etc.) exist everywhere, averaging 2400μSv/year.
Bananas contain radiation due to their rich potassium content, 1 banana ≈ 0.1μSv radiation, but the human body metabolizes and excretes excess potassium, preventing radiation accumulation and causing no harm.
Natural cosmic radiation exists at high altitudes. The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) calculated high-altitude cosmic radiation ≈ 3μSv per hour.
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多少辐射剂量是安全的？
The risks posed by the dental disease itself far outweigh the risks from the X-ray radiation. Therefore, we should not avoid necessary X-ray examinations due to unfounded fears.
The doses from periapical and panoramic radiographs are so low they can be performed as clinically needed, as their doses are far lower than annual natural background radiation — equivalent to eating a few extra bananas or taking a short flight. For higher-dose CBCT, limiting scans to no more than 3-4 times per year is generally recommended.
特殊人群防护指南
Essential dental treatment can usually be performed during the 4th to 6th months of pregnancy. However, radiography is certainly not recommended. If necessary, abdominal shielding with a lead apron is mandatory, and CBCT should still be avoided.
无论男性或女性，都建议在接受口腔放射检查后等待3个月再作怀孕计划。因为放射性物质在体内需要2-3个月才能完全排出体外。不过口腔检查最常用的根尖片辐射剂量极低，常规1-4张根尖片的辐射对胚胎损害可忽略不计。
建议备孕前6个月进行口腔检查，完成必要的口腔治疗，因为口腔疾病的治疗（如根管治疗）需较长时间（1-2个月），且治疗中可能需多次拍片。
Children are more sensitive to radiation due to them being in a critical period of growth and development. Therefore, the radiation dose for pediatric dental radiography should be halved, and digital radiography should be prioritized.
The thyroid gland is highly sensitive to radiation and dental X-rays are taken near the neck. Therefore, individuals with thyroid nodules should wear a lead thyroid collar during dental radiographic examinations to protect the thyroid.
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