Dental X-Rays: How Much Radiation, Which Types and How Often

Are dental X-rays safe, and how much radiation do they use?

Dental X-rays use very low doses, and the American Dental Association (ADA) says the risk of harmful effects is very small. The ADA also says doses are much lower now than in the past because of advances in technology. It still recommends X-rays in moderation, to lessen exposure.

For context, the ADA says radiation exposure from dental imaging is a minor contribution to the total exposure from all sources. The ADA also says dental imaging accounts for less than 1 percent of the collective annual dose from medical imaging such as CT scans. These are population-level figures from the ADA, not a measure of your own dose.

This guide uses the word “safety” in the way the ADA and FDA do: dentists weigh the benefit of the image against a small radiation risk. Your dentist will talk with you about why an X-ray is needed.

What do dental X-rays show?

They show what a mouth exam cannot. The ADA says X-rays can confirm that teeth are healthy or reveal damage or disease not visible during a dental exam, such as new cavities or impacted teeth.

The practice’s Technology page describes its digital X-rays this way: “Digital x-rays are a crucial diagnostic tool that helps us gain a better understanding of the inner workings of your mouth, more specifically the teeth, roots, and alveolar bone.” It also says: “If the image comes out blurry, we can instantly retake a new one.” Those are the practice’s own statements. See the practice’s technology page for the full text.

Which types of dental X-rays are used?

The three common types are bitewing, periapical and panoramic. A JADA patient page says each type helps the dentist see different areas of the mouth.

The JADA page says cone-beam technology uses a series of images to make a 3D picture. Because it relies on multiple images, its radiation exposure is higher than that of commonly used X-rays, and it is used when more detailed information is needed.

The practice’s Technology page says: “We typically utilize cone beam CT scans when a regular x-ray is not enough.” That fits the FDA and ADA view below.

How often do you need dental X-rays?

It depends on you. The ADA says there is no “one size fits all” interval. How often depends on four things:

1. Your present oral health
2. Your age
3. Your risk for disease
4. Any signs or symptoms of oral disease

The ADA says children and teens may need X-rays more often than adults because their teeth and jaws are still developing. It also says new patients may get X-rays so the dentist has a baseline for later comparison.

Older guidance gives a feel for the range. A 2012 FDA and ADA patient-selection table listed a bitewing exam at 6 to 12 month intervals for some patients at increased risk of cavities, and at 24 to 36 month intervals for others. The ADA says panels of dentists have since updated that guidance, and that the newer recommendations emphasize a thorough clinical exam before images are taken. Use the table as background only. Your dentist makes the call.

The ADA says X-rays should be taken only when the dentist believes they will provide needed diagnostic information. In other words, an X-ray is not routine by the calendar. It is a clinical decision.

What should I do if I switch dentists?

Ask both offices to help forward your images. The ADA says that if a previous dentist has images of you, the new dentist may ask for copies instead of ordering new ones. That can avoid a repeat X-ray. Ask the old office what format it can send and how long it takes.

What does the dental team do to limit exposure?

Dental teams use several steps, which the ADA lists. These include:

• Ordering X-rays based on clinical need, and making a good-faith effort to use images from earlier exams.
• Using digital receptors instead of conventional film.
• Restricting the X-ray beam to the area being examined, an approach called rectangular collimation.
• Using cone beam CT only when lower-exposure options will not give the needed information.
• Following federal, state and local radiation safety rules.

Good positioning matters too. The ADA says the team makes sure you are positioned properly and the beam is focused on the area of interest. A well-placed image does not need to be retaken.

For children, the ADA supports Image Gently, an effort to size X-ray exposure to a child. For adults, it points to Image Wisely, a program to limit X-ray exposure in adults to only that which is needed. The glossary has a plain entry on radiation dose.

Why did the lead apron go away?

The ADA’s current advice is that lead aprons and thyroid collars are no longer recommended for any dental imaging. It says these shields can block the main X-ray beam, which may mean additional X-rays are needed, something your dentist wants to avoid. Better protection comes from proper positioning, a small beam size and dose-reduction steps. The ADA says organizations such as the American Academy of Oral and Maxillofacial Radiology and the American Association of Physicists in Medicine have supported dropping lead shielding.

The ADA adds that shielding may still be used in some practices because of local regulations. If you have questions, ask your dentist.

This applies to pregnancy too. The ADA says abdominal and thyroid shielding is no longer needed for patients of all ages and health statuses, such as pregnancy. If you are or might be pregnant, tell your dentist anyway. The dentist can decide whether an image is needed now or can wait.

What does the FDA say about cone beam CT?

The FDA says cone beam CT typically delivers more radiation than conventional dental X-rays, though generally less than other CT exams. It says the ADA and the FDA recommend that dentists take dental X-rays, including cone beam CT, only when necessary for the diagnosis or treatment of disease.

The FDA also says concerns about radiation exposure are greater for younger patients because they are more sensitive to radiation and have a longer lifetime for ill effects to develop. If a 3D scan is suggested for your child, it is fair to ask why a regular X-ray is not enough, what the scan will show, and whether any lower-dose option would do.

The practice lists cone beam CT scans among its technology. That is a description of equipment, not a promise that any patient will need one.

How does a dental X-ray compare with other radiation?

We are all exposed to radiation every day, from natural and man-made sources. The ADA cites the National Council on Radiation Protection and Measurements, which estimated that the mean effective radiation dose from all sources in the U.S. is 6.2 millisieverts per year. About half of that comes from natural sources such as soil and radon, and about half from man-made sources. The ADA adds that about half of the man-made exposure comes from computed tomography (CT) scanning.

This helps put dental imaging in context, but the ADA does not use it as a reason to skip care. It says dentists must weigh the benefits of each radiograph against the risk of exposing a patient to X-rays, whose effects accumulate from multiple sources over time. The dentist, who knows your health history and your vulnerability to oral disease, is the person who can make that judgment. Your dentist will talk with you about what to expect.

What about X-rays for children?

Children may need X-rays more often than adults, and the team takes extra care. The ADA says children and teens may require X-rays more often because their teeth and jaws are still developing. A dentist may want to see where adult teeth are forming, check for decay between baby teeth that touch, or watch how the jaw grows.

At the same time, the FDA says younger patients are more sensitive to radiation. That is why the ADA supports Image Gently, which aims to “child size” X-ray exams. If your child needs an image, you can ask:

1. What will this image show that an exam cannot?
2. Can you use a recent image from another dentist?
3. Is a regular X-ray enough, or is a 3D scan being considered, and why?
4. How will you position my child to avoid a retake?

Our guide to a child’s first dental visit explains what a young child’s visit looks like.

What happens when I have X-rays taken?

The steps are short. The exact order varies by office.

1. The team asks about your health and why an image is needed.
2. You are positioned in the chair with the sensor, film or machine in place. For a bitewing, you bite down on the sensor with your back teeth.
3. The image is taken. Rectangular collimation keeps the beam on the area of interest.
4. A digital sensor sends the image to a screen. If the image is blurry, the team may retake it. The practice says it can retake a blurry digital image instantly.
5. The dentist reviews the image with the rest of the exam and shows you what it reveals.

Tell the team if the sensor is uncomfortable, so they can adjust.

What if I decline X-rays?

You may decline, but talk it through first. A dentist cannot see what lies under a filling or between teeth without an image. If you decline, the dentist can still examine what is visible, but some problems may go unseen. If you have concerns about radiation, tell the team why. Ask whether any images can wait, whether a smaller set would answer the question, or whether images from another office exist. Your dentist will talk with you about the trade-offs and what to expect. The decision is yours.

What questions can I ask about my X-rays?

Ask short, direct questions. A good office is used to them.

Our guide to what happens at a dental exam and cleaning explains where X-rays fit in a visit. The practice’s dental exam page describes the exam itself.

Next step

If you have questions about X-rays, bring them to your visit. Read about the dental exam, then call (636) 273-5866 or request an appointment.