Understanding dental X-rays: why, how often and how safe

What X-rays can show

• Cavities between teeth or under existing fillings
• Infection or abscesses at the tip of a root
• Bone loss from gum disease
• Wisdom teeth and other teeth that haven't come in
• Cracks, cysts and some growths in the jaw
• How a child's adult teeth are developing
• The fit of crowns and the shape of roots before a root canal or extraction

Common types

Bitewing X-rays show the crowns of the upper and lower back teeth together. They're mainly used to find decay between teeth and check bone levels.

Periapical X-rays show a whole tooth from crown to root tip. They help diagnose a sore tooth, an infection or a cracked root.

Panoramic X-rays take one wide image of both jaws, all the teeth and the jaw joints. They're useful for wisdom teeth, children's tooth development and planning for implants or dentures.

Cone beam CT (CBCT) creates a 3D image. It's used for specific needs, such as some implant planning, and is not part of a routine checkup. We don't have CBCT in our office; if you need a 3D scan, we refer you.

How often you need them

There's no one-size schedule. Canadian guidance is that dental X-rays should be taken only when the dentist expects them to help with diagnosis or treatment. Someone with frequent cavities or active gum disease may need bitewings more often than someone with a healthy mouth and no new fillings in years.

New patients may need a set of X-rays if recent ones aren't available. If you've had X-rays at another office, ask them to send copies to avoid repeating them.

What to expect when X-rays are taken

Taking a dental X-ray takes only a moment. For bitewing and periapical images, a small digital sensor is placed inside your mouth and you bite gently to hold it. The team steps away briefly while the image is captured, and it appears on the screen within seconds.

For a panoramic X-ray, you stand or sit while the machine moves around your head. You'll bite on a small guide and stay still for several seconds. If you have a strong gag reflex, mention it. Smaller sensors, different positions and slow breathing through the nose can help.

Safety and radiation

Everyday life exposes us to natural background radiation from the ground, air and food. A digital dental X-ray adds only a small amount compared with medical scans. Digital sensors need less radiation than older film.

The beam is aimed only at the area being imaged. Your dental team may use a protective apron or thyroid collar when appropriate. At our office, we use digital X-rays and take them only when needed.

If you're pregnant or think you might be, tell the team. Needed X-rays can still be taken safely, while routine ones are often postponed.

Related services

More patient guides

• What causes bad breath, and what can you do about it?
• Canker sore or cold sore: how to tell the difference
• How to care for your clear aligners
• Canadian Dental Care Plan: who qualifies and how it works

Trusted health information

• Caring for your teeth and mouth (Government of Canada)
• Taking care of your child's teeth (Government of Canada)
• Oral health (Government of Canada)