ARPANSA, Australia's radiation protection agency, lists a typical dental X-ray at about 0.01 millisieverts (mSv). The same agency estimates that Australians receive around 1.7 mSv a year from natural sources, which works out to roughly 0.005 mSv a day. In other words, a dental X-ray adds about as much radiation as two ordinary days of simply living on earth.
Numbers like these are easier to judge side by side, so this article puts the dental dose next to other everyday and medical exposures, and explains why dentists still keep X-rays to what is needed.
The comparison in one table
The figures below come from ARPANSA's public guide to ionising radiation and health. They are typical values: the actual dose from any one image depends on the machine, the settings and the type of view taken.
| Exposure | Typical dose | Roughly equal to |
|---|---|---|
| Dental X-ray | 0.01 mSv | About 2 days of natural background radiation |
| Chest X-ray | 0.02 mSv | About 2 dental X-rays |
| 20-hour flight | 0.1 mSv | About 10 dental X-rays |
| Abdominal CT scan | 10 mSv | About 1,000 dental X-rays |
| Natural background, one year in Australia | 1.7 mSv | About 170 dental X-rays |
A long flight carries more radiation than a dental X-ray because there is less atmosphere above you to filter cosmic radiation at cruising altitude.
Where background radiation comes from
Natural radiation is part of normal life. It comes from radioactive elements in rocks and soil, radon gas that seeps from the ground into buildings, small amounts in food and water, and cosmic radiation from space. Nobody can avoid it, and the amount varies a little depending on where you live and how much you fly. A dental X-ray is a small addition on top of that steady background.
Why the dental dose is so small
Dental X-rays look at a small area with a narrow, tightly aimed beam, and the teeth and jaw need relatively little radiation to produce a clear image. Most practices now use digital sensors, which are more sensitive than the old film and can work with shorter exposures. Larger views, such as a panoramic (OPG) image of the whole jaw or a 3D cone beam scan, involve more radiation than a single small film, but they are still taken only when the extra information is needed. Our guide to bitewing and OPG X-rays explains what each view shows.
Low dose still means only when needed
Radiation protection rests on two ideas: an image should only be taken when it is justified by a clinical question, and when it is taken, the dose should be kept as low as reasonably achievable while still giving a useful picture. Dental X-ray equipment in Australia is licensed and regulated under state radiation laws, and the people who use it must be appropriately trained.
That is why the timing of X-rays is tailored to the person. Someone with healthy gums and a low risk of decay may only need bitewings every couple of years, while someone who gets new cavities often, has active gum disease or is in the middle of treatment may need them more frequently. Our article on how often you need a check-up and X-rays goes into this in more detail.
Lead aprons are no longer routine
Many people remember wearing a heavy lead apron for dental X-rays. Current guidance has moved away from routine shielding, because modern dental beams are tightly aimed at the mouth, the scatter reaching the body is extremely small, and a shield can get in the way of the image and lead to a repeat X-ray. At Lumi Dental we do not use lead aprons or thyroid collars, in line with that guidance.
Pregnancy and children
Dental X-rays are generally considered safe during pregnancy when they are clinically needed, because the dose is very low and the beam is aimed well away from the abdomen. Some routine images may be left until after the birth, but X-rays needed to diagnose pain or infection should not be delayed. Our article on dental X-rays during pregnancy covers this in more depth. Children are imaged on the same principle of need, and our guide to dental X-rays for kids explains how often they are usually taken.
Questions we hear about X-ray safety
Does radiation from X-rays add up over a lifetime?
The radiation does not stay in your body after the X-ray is taken. Radiation protection does, however, treat the small risks from separate exposures as adding together over a lifetime, which is one reason dentists ask when your last X-rays were taken and avoid repeating images without a reason.
Can I say no to an X-ray?
Yes. You can ask what the X-ray is looking for and how it would change your treatment. If you decline, your dentist will explain what might be missed, such as decay between teeth or bone changes that cannot be seen in the mouth.
Can I bring X-rays from my last dentist?
Yes, and recent images can sometimes avoid a repeat. Our guide to who owns your dental X-rays explains how to request copies.
Ask us about your X-rays
At Lumi Dental in Melrose Park we use digital X-rays and an Orthophos 3D X-ray unit for OPG and 3D scans when they are needed, and we are happy to explain why any image is being recommended. Learn more about our general dental care or see our current offers to book a check-up.
