Why images are needed when the mouth looks fine
Decay between two teeth starts where they touch, hidden from sight and beyond the reach of a mirror. An x-ray can catch it while it's still in the enamel, which is the reason for taking one early. Left untreated, decay can pass into the softer dentin underneath, where it tends to spread more quickly and the repair becomes larger. The same goes for everything under the gum: bone loss, an abscess that can be present for months without symptoms, cysts, impacted wisdom teeth.
One image is a snapshot. A series taken over several years shows direction, and direction is what tells us whether a shadow between two teeth is stable enough to watch or moving quickly enough to treat. If you've had x-rays taken elsewhere recently, please mention it when you call.
Bitewings, periapicals and panoramic images: what each one shows
- Bitewing
- You bite on a tab and the image captures the crowns of the upper and lower back teeth together. This is the routine image. It shows decay between teeth, decay under fillings, and the height of the bone crest. It doesn't show root tips.
- Periapical
- A periapical image shows one tooth from the crown to past the end of the root. It's the image for a tooth that hurts, a tooth being assessed for root canal treatment, a suspected abscess, or a site being planned for a dental implant.
- Full mouth series
- A combination of bitewings and periapicals covering every tooth and the bone around it. It's usually taken for a new patient with a complicated history, or for someone who hasn't had images taken in years, and it's rarely repeated after that.
- Panoramic
- A single wide image of both jaws, the sinuses and the jaw joints, taken as the machine rotates around the head. It's useful for wisdom teeth, cysts, fractures and the shape of the jaws. It shows less fine detail, so it doesn't replace bitewings.
How much radiation is in a dental x-ray
Everyone is exposed to radiation continuously, from soil and granite, from radon, from cosmic rays, and from ordinary food. Exposure is higher at elevation than at sea level, and flying raises it again for a few hours.
A dental x-ray is small in that context. A set of bitewings falls in roughly the same range as the background dose received in an ordinary day, and less than a flight across the country. Even a small dose is worth managing carefully, so we follow the principle called ALARA, as low as reasonably achievable: an image is taken when there's a diagnostic reason for it, using the fewest images and the lowest exposure that will answer the question.
Shielding, pregnancy and keeping exposure down
- The lead apron and thyroid collar
- These were standard for decades, though national guidance has moved away from routine shielding. The beam is aimed at a small area, and a collar sitting out of position can block what needs to be seen, which means a retake and a second exposure. Please tell us what you'd prefer before imaging begins.
- If you are pregnant, or think you might be
- Please tell us before any image is taken. Routine screening images can usually wait. Where something does need diagnosing, dental imaging is generally considered acceptable during pregnancy, and an undiagnosed infection carries risks of its own. We'll make the decision together at your appointment.
- Children
- Children are more sensitive to radiation than adults, so we image them less often and with the settings adjusted for size. Their bitewings mainly watch the contacts between the back teeth, where cavities tend to start.
Dental x-ray questions
Can I refuse x-rays?
Yes. Imaging is always your choice, and we're glad to talk it through with you. It helps to know what declining means: without images, the examination covers part of each tooth and none of the bone, so the picture is incomplete. If cost or radiation is on your mind, please bring it up and we'll go over the options together.
Why do I need new x-rays when I had some two years ago?
An x-ray is a picture of one moment. Decay progresses and bone levels change, and much of the value lies in comparing images over time. If your previous images are recent enough, they may still be useful, so please mention them when you call.
Do digital x-rays really use less radiation than film?
Yes. A digital sensor is more sensitive than film emulsion, so it needs less exposure to produce a readable image, and no exposure is wasted on a film that develops poorly.
X-rays make me gag. What can be done?
Several adjustments can help, so please tell us before we start. The positioning can be changed, the edges can be cushioned, and breathing slowly through the nose helps many people. There's no need to push through discomfort, which often ends in a poor image that has to be taken again.
What happens if you find something?
We'll show you the image, explain what we're seeing, tell you how urgent it is, and describe what happens if it's left untreated. Some findings are watched rather than treated. If a tooth is hurting now, that's a dental emergency.