Dental x-rays: types and safety

Reviewed by Dr. Samar Fadavi, DDS

Short answer: Dental x-rays show what a visual exam cannot: decay between teeth, infection at the root tips, bone levels, wisdom teeth and problems under old fillings. Modern digital x-rays use very low doses of radiation, often less than you receive from everyday background sources in a day or two. How often you need them depends on your age, risk and dental history, not a fixed schedule.

Why dentists take x-rays

A dentist can see a lot by looking at your teeth and gums, but much of each tooth is hidden. The sides of back teeth touch each other, roots sit inside the bone, and problems can grow under fillings and crowns without any visible sign. X-rays, also called radiographs, let the dentist see inside and around the teeth.

They help find problems early, when treatment is smaller and simpler. They also guide treatment such as root canals, implants and extractions, and they create a record to compare against in future visits. This guide explains the main types, what each one shows, how safe they are, how often they are needed and what to expect. It is general information for patients in Scarborough, the Danforth and East Toronto.

What x-rays can show

• Cavities between teeth and under existing fillings or crowns.
• Infection or an abscess at the tip of a root.
• Bone loss from gum disease.
• Cracks in roots, though small cracks are not always visible.
• Impacted or developing teeth, including wisdom teeth.
• Cysts, growths and other changes in the jaw.
• The shape and length of roots before a root canal or extraction.
• Bone height and width before planning an implant.
• Changes in children’s teeth and jaws as they grow.

Types of dental x-rays

Bitewing x-rays

Bitewings show the crowns of the upper and lower back teeth together, as you bite on a small tab or sensor holder. They are the main way to find cavities between back teeth and to check bone levels between teeth. Most adults have a set of two or four bitewings at regular intervals.

Periapical x-rays

A periapical x-ray shows one or two whole teeth from crown to root tip, plus the bone around the root. It is used when a tooth hurts, to look for infection, and during root canal treatment.

Panoramic x-rays

A panoramic x-ray is taken by a machine that moves around your head while you stand or sit still. It shows all the teeth, both jaws, the jaw joints and the sinuses in one wide image. It is useful for wisdom teeth, planning orthodontics, checking the jaw in people with dentures, and looking at overall development in children.

Cone beam CT (3D imaging)

Cone beam computed tomography, or CBCT, creates a three-dimensional view of the teeth and jaw. It is used for implant planning, complex root canals, impacted teeth and assessing bone and nerve position. CBCT uses more radiation than a regular dental x-ray but much less than a medical CT scan, so it is used only when the extra detail will change the treatment plan. Our clinic offers CBCT 3D imaging when it is needed. Our dental implants and root canal pages explain how it helps plan treatment.

Occlusal x-rays

Occlusal x-rays show the floor or roof of the mouth. They are used less often, sometimes for children, for salivary stones or to look at teeth that have not come in.

How safe are dental x-rays?

Everyone is exposed to small amounts of natural radiation every day from the ground, the air, food and even air travel. Dental x-rays add a very small amount to that. A set of digital bitewings delivers roughly the same radiation as one to two days of normal background exposure in Canada. A panoramic x-ray is similar to a few days, and a cross-country flight adds more than a set of bitewings.

Digital sensors need much less radiation than old film, and the x-ray beam is narrowed to the area being imaged. Dental teams also follow the principle of keeping doses as low as reasonably achievable, which means x-rays are taken only when they will help with your care.

The bigger risk is often not taking a needed x-ray, because a hidden cavity or infection can grow until it needs a root canal or extraction.

Shields and aprons

Lead aprons and thyroid collars were once used for every dental x-ray. Because modern equipment focuses the beam so precisely, guidance in Canada and elsewhere has been changing, and in many cases shields are no longer considered necessary. Your dental team follows current Ontario rules for the equipment they use. If a shield makes you feel more comfortable, you can ask about it.

How often you need x-rays

There is no single schedule for everyone. Dentists in Canada decide based on your age, your history and your risk of cavities and gum disease. As a general guide:

• Adults with healthy teeth and low cavity risk may need bitewings every two to three years.
• Adults with higher risk, such as frequent cavities, dry mouth, many fillings or gum disease, may need them every year or more often.
• Children and teens often need bitewings more often than adults because their teeth are changing and cavities progress faster in baby teeth, typically every one to two years depending on risk.
• New patients may need a set of x-rays to create a starting point, unless recent images can be sent from a previous dentist.
• Symptoms such as pain, swelling or a broken tooth usually call for a periapical x-ray of that area.

Our guide on what type of dental exam you need explains how exams and x-rays fit together.

What to expect when x-rays are taken

1. Health check. You will be asked whether you are or might be pregnant, and about any recent x-rays elsewhere.
2. Positioning. For bitewings and periapicals, a small sensor is placed in your mouth with a holder that you bite on gently. For a panoramic x-ray, you stand or sit in the machine with your chin on a rest.
3. Staying still. You hold still for a second or two while the image is taken. For a panoramic or CBCT scan, the machine rotates around you for several seconds.
4. Viewing. Digital images appear on screen within seconds, and the dentist can enlarge them and show you what they see.

If you have a strong gag reflex, tell the team. Smaller sensors, breathing through the nose, distraction and taking images quickly all help. A panoramic x-ray can sometimes replace some intraoral images for people who cannot tolerate sensors.

X-rays during pregnancy

Routine x-rays are usually postponed until after pregnancy. If you have a dental problem that needs diagnosis, such as pain or swelling, a dental x-ray can be taken safely during pregnancy. The beam is aimed at the mouth, far from the abdomen, and the dose is very small. Untreated dental infection can be more harmful than a needed x-ray. Always tell us if you are or may be pregnant.

X-rays for children

Children’s teeth and jaws change quickly, so x-rays help check for cavities between baby teeth, confirm that adult teeth are developing, and spot crowding or missing teeth early. Child sensors are smaller, and doses are adjusted for size. We take x-rays for children only when they will guide care. Our guide to your child’s first dental visit explains early check-ups.

Steps to make the most of your x-rays

1. Share recent images. If you have had x-rays at another clinic in the last year or two, ask them to send copies. It may avoid repeat images.
2. Ask to see them. Looking at your own x-rays with the dentist helps you understand what is happening and why treatment is suggested.
3. Tell us about changes. New pain, sensitivity or swelling helps the dentist choose the right type of image.
4. Keep regular visits. Comparing images over time shows whether bone or decay is changing.
5. Ask about coverage. Many insurance plans and the Canadian Dental Care Plan include x-rays at certain intervals. Our team can check your plan.

What to avoid

• Do not refuse all x-rays out of worry. Hidden problems can grow, and the radiation dose is very small.
• Do not assume you need the same schedule as a friend or family member. Timing depends on your own risk.
• Do not forget to mention pregnancy or recent medical imaging.
• Do not move during the image. A blurry x-ray may need to be repeated.
• Do not rely on x-rays alone. They work together with a careful visual exam, gum measurements and your symptoms.

Limits of x-rays

X-rays are very helpful, but they do not show everything. Very early cavities, small cracks, gum problems on the front or back of teeth and soft tissue changes in the mouth may not appear. Some decay looks smaller on an x-ray than it really is. That is why your dentist combines x-rays with a close visual exam, testing of sensitive teeth and gum measurements. Oral cancer screening, for example, is done by looking and feeling, not by x-ray. Our guide to oral cancer explains what we check.

Your x-ray records

Your dental x-rays are part of your health record and are kept securely. If you move to another dentist, or need a second opinion or a referral, you can ask for copies to be sent. Digital images are easy to share electronically with your consent.

How to read your own dental x-ray

Dental x-rays can look confusing at first, but a few basics help you follow along when the dentist shows you an image:

• Bright white areas are dense materials such as metal fillings, crowns and root canal fillings.
• Light grey areas are enamel and the outer layers of the tooth, plus healthy bone.
• Darker areas are less dense: the nerve space inside the tooth, soft tissue and air.
• A dark shadow in the side of a tooth can be a cavity, where minerals have been lost.
• A dark circle at a root tip may be a sign of infection in the bone.
• A lower bone line between teeth may show bone loss from gum disease.

Ask your dentist to point out what they see. Understanding your own images makes treatment decisions clearer and easier.

When to see a dentist

Book a visit if:

• A tooth hurts when you bite, is sensitive to hot or cold, or keeps you awake.
• You notice swelling, a pimple on the gum or a bad taste.
• It has been more than two years since your last x-rays and check-up.
• Your wisdom teeth feel sore or your gums at the back of the mouth are swollen. Our wisdom teeth guide explains what to watch for.
• You are thinking about implants or orthodontic treatment.

Our family dentistry page explains check-ups, cleanings and x-rays at our Danforth Avenue clinic.

Questions about dental x-rays

Are dental x-rays safe?

Yes. Digital dental x-rays use very low doses, often similar to a day or two of natural background radiation. They are taken only when they help your care.

Why do I need x-rays if my teeth feel fine?

Cavities between teeth, infections at the root and bone loss often cause no symptoms until they are advanced. X-rays find them early.

Can I have dental x-rays while pregnant?

Routine x-rays are usually delayed, but needed x-rays for pain or infection can be taken safely during pregnancy.

How often should children have x-rays?

Often every one to two years, depending on cavity risk and development. Your dentist decides based on your child’s needs.

What is the difference between a panoramic x-ray and CBCT?

A panoramic x-ray is a flat image of all the teeth and jaws. CBCT is a three-dimensional scan used when more detail is needed, such as for implant planning.

Can my old dentist send my x-rays?

Yes. With your consent, most clinics can send digital x-rays electronically, which may avoid repeating them.

Are x-rays covered by insurance or CDCP?

Many plans include x-rays at certain intervals. Our team can check your coverage. See our CDCP page for details.

Do I need new x-rays if I switch dentists?

Not always. If your previous clinic sends recent images that are clear and current, your new dentist may only need to add the views that are missing.