Why Do Dentists Take X-rays?

Dentists take X-rays to see what an eye-level exam cannot: decay between teeth, infection at the root tip, and changes in the bone that holds teeth in place. Whether you need X-rays at a given visit depends on your risk, symptoms, age and how recent and useful your last images are, not on a fixed calendar.

Key Takeaways

• Dental X-rays show hidden problems such as cavities between back teeth, root-tip infection and bone loss from gum disease, which a visual exam alone often misses.
• There is no single X-ray schedule for everyone. The American Dental Association says there is no "one size fits all" interval, and the Canadian Dental Association calls frequency a matter of clinical judgment.
• Health Canada's Safety Code 30 says routine or screening X-rays without a prior clinical exam and justification should not be performed.
• Recent X-rays from another office can often be transferred, which may avoid repeat exposure.
• You can always ask what question an X-ray is meant to answer and how the result could change your care.

Why do dentists take X-rays in the first place?

A dental X-ray, also called a dental radiograph, is an image made with a small, controlled dose of ionizing radiation that passes through teeth and bone and is captured on a sensor or film. Dense structures such as enamel and bone appear light, while softer or less dense areas, including decay, appear darker. That difference in shading is what lets a dentist spot problems below the surface.

The American Dental Association puts the purpose simply: dentists use X-rays to help diagnose damage and disease that is not visible during a regular dental examination. A tooth can look healthy from the outside while decay spreads between two teeth, or while an infection forms at the tip of a root. X-rays let the dentist find those problems when treatment is often smaller and simpler.

Most dental offices now use digital X-rays, where a small sensor sends the image straight to a computer so it can be enlarged, brightened and compared with earlier images. The joint ADA and FDA patient-selection guidelines note that digital imaging may offer reduced radiation exposure.

X-rays are one tool among several. Your dentist still examines your teeth and gums, measures gum pockets, tests teeth for sensitivity and listens to what you describe. The image adds information to that exam. It does not replace it.

What X-rays can show that a visual exam may miss

A visual dental examination is essential, but it has limits. The surfaces of teeth that face the cheek and tongue can be seen directly. The contact points between back teeth, the roots and the bone around them cannot. Dental radiographs fill in those blind spots.

Radiographs may help a dentist evaluate:

• decay between teeth or under an existing filling or crown;
• how close a deep cavity or filling sits to the nerve of the tooth;
• bone levels around teeth, which matters in assessing gum (periodontal) disease;
• the area around a root tip when an abscess is suspected;
• unerupted, impacted or extra teeth, including wisdom teeth;
• the fit and condition of crowns, bridges, root canal fillings and implants;
• changes compared with earlier images of the same area.

Different X-ray views answer different questions. These are the common types:

X-ray type	What it shows	Often used for
Bitewing	Crowns of upper and lower back teeth in one image	Cavities between teeth, bone level between teeth
Periapical	One or a few whole teeth, from crown to root tip, with surrounding bone	Toothache, suspected abscess, root and bone changes
Occlusal	The floor or roof of the mouth	Selected developmental or injury questions
Panoramic	All teeth, both jaws and nearby structures in one wide image	Wisdom teeth, broad overviews, some treatment planning
3D CBCT	A three-dimensional volume of a selected area	Selected implant, surgical or complex root questions

X-rays also have blind spots of their own. Some cracks, very early enamel changes and many soft-tissue conditions do not show clearly on standard dental radiographs. That is why the dentist combines the image with probing, testing, your history and what you report about pain or sensitivity. When a flat image cannot answer a three-dimensional question, a dentist may discuss cone-beam imaging; our guide comparing CBCT and regular dental X-rays explains when that happens.

How often should you get dental X-rays?

Patients often ask how often they should get dental X-rays. The evidence-based answer is that it depends on the person. The American Dental Association states that there is no "one size fits all" interval between dental X-rays. The Canadian Dental Association's position on X-radiation says the frequency of a radiological examination is a matter of clinical judgment.

The ADA and FDA guidelines use a matrix that weighs age, stage of dental development and risk. Someone with active decay, many fillings or periodontal disease may need images more often. Someone at low risk, with stable exams and recent adequate images, may go longer between them. The guidelines also say that a patient's risk status can change over time and should be reassessed.

Factors your dentist weighs include:

• age and stage of tooth development;
• cavity (caries) risk, including diet, dry mouth and past decay;
• gum health and history of periodontal treatment;
• symptoms and what the exam finds;
• medical history and medications;
• whether previous images exist and still answer today's question;
• the treatment decision the image would inform.

"It has been a year" is not, by itself, a clinical reason for an X-ray. Time since the last image matters because disease can develop in the interval, not because a date has passed. Health Canada's Safety Code 30 is direct on this point: routine or screening X-ray examinations with no prior clinical evaluation and no clinical justification should not be performed, including examinations of children to monitor dental development.

The guiding principle is often called ALARA, short for "as low as reasonably achievable". ALARA applies after imaging is justified. It means using good technique and the fewest images needed for the diagnostic task. It does not mean skipping an X-ray that would change your care. For more on visit timing in general, read how often you should go to the dentist.

New patients versus recall visits

A new-patient exam often includes X-rays when no recent, adequate images are available, because the dentist needs a baseline to plan care. A baseline does not mean every possible view for every new patient. The ADA and FDA guidelines state that radiographic screening to detect disease before a clinical exam should not be performed; the history and exam come first, and the X-ray selection follows the findings.

If you have recent images from another practice, arrange a transfer before your first visit. The Canadian Dental Association advises dentists to try to obtain a patient's existing radiographs rather than routinely prescribing new ones. Transferred images may not answer every current question, but they often reduce what needs to be retaken.

Recall visits focus on change. A stable, low-risk patient may need fewer images than someone with new cavities, a deep filling under watch or gum concerns. Your dentist should be able to explain why today's proposed images match or differ from what was done last time.

Different ages have different needs:

• Children: teeth are developing and cavities can progress quickly in baby teeth. Health Canada's Safety Code 30 says children's X-rays must use techniques adjusted for size and age.
• Teens: wisdom teeth, orthodontic questions and sports injuries may prompt specific views.
• Adults: decay under older fillings and gum disease become more common considerations.
• Seniors: dry mouth from medications, root-surface decay and planning for crowns, bridges, dentures or implants may affect imaging decisions.

Symptoms that may prompt X-rays sooner

Targeted X-rays are commonly considered when you have:

• tooth pain or sensitivity that lingers;
• swelling, a pimple-like bump on the gum or other signs of possible infection;
• a cracked, broken or knocked tooth after an injury;
• pain when biting;
• a loose tooth;
• problems after recent dental treatment;
• a tooth being assessed before a crown, root canal or extraction.

An injury or suspected infection may call for a same-day image as part of diagnosis. That is different from routine recall bitewings, and the image is usually limited to the area in question. The ADA and FDA guidelines note that intraoral X-rays are useful for evaluating dental injuries.

The absence of pain does not always mean the absence of disease. Cavities between teeth and early bone loss are often found on X-rays before symptoms begin. That is one reason risk-based imaging exists, but it is still not a reason for X-rays nobody can justify.

Are dental X-rays safe?

Dental X-rays use low doses of radiation, and professional guidance is built around keeping them low. According to the American Dental Association, citing a 2023 study in Radiology, dental imaging accounts for less than 1 percent of the estimated collective annual effective dose that Americans receive from medical imaging. That is a population figure, not a personal dose, and the ADA still stresses that every exposure should be justified.

Several practical steps reduce exposure: digital sensors, limiting the beam to the area being imaged, careful positioning so images do not need retaking, and using existing images when they still answer the question. Our guide to dental X-ray radiation and safety covers this in more detail.

Lead aprons and thyroid collars

Advice on shielding has changed, and Canadian and American guidance currently differ. In 2024 the American Dental Association recommended discontinuing lead aprons and thyroid collars for patients, noting they can block the X-ray beam and lead to retakes. Health Canada's Safety Code 30 says a thyroid shield must be provided when it will not interfere with the needed diagnostic information, but should not be used for most panoramic images, where it would sit in the beam. Your dental team follows the rules that apply in Nova Scotia and can explain what they use and why.

Pregnancy

Tell the dental team if you are pregnant or might be. Health Canada's Safety Code 30 states that radiation to the fetus from dental X-rays is generally accepted to be extremely low when the abdomen is not directly exposed. The Canadian Dental Association notes that elective X-rays may be deferred until after pregnancy, while Safety Code 30 references guidance that pregnant patients needing essential or emergency treatment should receive the minimum number of radiographs needed. A painful infection is not something to leave undiagnosed.

Children

Children are more sensitive to radiation than adults. Safety Code 30 requires child-specific settings that typically reduce the machine's output, and it describes the thyroid as especially sensitive in children. The ADA supports the Image Gently campaign, which encourages "child-sizing" exposures. Parents can ask what settings are used and why a particular image is needed now.

How to talk through an X-ray recommendation

A clear conversation builds trust on both sides. Useful questions include:

1. What are you hoping to learn from this image? The answer should name a specific clinical question.
2. Are my previous X-rays still useful? A transfer may reduce repeat exposure.
3. What happens if we wait? For routine images, ask about the trade-off of delaying.
4. Which type of image, and how many? Bitewing, periapical and panoramic views are not interchangeable.
5. How will the result change my options? Imaging should influence diagnosis, monitoring or treatment.

You may decline an X-ray. If you do, you should also hear how that limits the dentist's ability to find hidden disease or plan treatment safely. Informed consent and informed refusal both depend on a real discussion of benefits and limits, and a dentist may be unable to proceed with some treatments, such as a root canal or extraction, without an image of the tooth.

If anxiety about radiation is behind your hesitation, say so. Professional organizations support imaging when the diagnostic benefit is expected to outweigh the risk for that patient. They do not support unnecessary exposures, and they also do not support withholding a needed image only because of worry without clinical context.

Getting dental X-rays in Truro and Colchester County

Landmark Dental Care is a family general practice at 125 Queen St in downtown Truro, in a Victorian Queen Anne–style home, serving patients from Truro, Bible Hill and across Colchester County. The practice uses digital dental X-rays as part of checkups, new-patient exams and emergency visits, and also offers 3D CBCT imaging for selected planning questions.

If you are moving your care to Truro, ask your previous dentist to send recent X-rays and records before your first appointment. The team can then review what is still useful and explain what, if anything, needs to be taken.

Coverage for X-rays varies. As of 2026, Nova Scotia's Children's Oral Health Program, billed through MSI, covers children aged 14 and younger with a valid Nova Scotia health card, and its yearly coverage includes one routine exam and two routine X-rays; private insurance must be used first where it applies. For adults and families asking about the federal program, see our Canadian Dental Care Plan page and call the office to confirm current participation and billing before your visit. Private plans often set their own X-ray limits, so check your plan booklet.

For a severe dental infection with spreading facial swelling, or trouble breathing or swallowing, call 911 or go to the Emergency Department at the Colchester East Hants Health Centre. For nurse advice at any hour, Nova Scotians can call 811.

FAQ

Do I need dental X-rays every six months?

Not necessarily. Six months is not a universal rule for X-rays, even if you see your dentist that often for checkups. Your dentist bases timing on your risk, symptoms, exam findings and whether recent images already answer the question.

Can a dentist find cavities without X-rays?

Some cavities are visible during an exam, but many between back teeth are not. Skipping X-rays can mean decay is found later, when it may need a bigger repair. Ask your dentist what can and cannot be checked without an image.

Why would a dentist want X-rays if nothing hurts?

Pain often shows up late with dental problems. X-rays can reveal decay between teeth or bone loss before you feel anything, when treatment may be simpler. The recommendation should still be explained in terms of your own risk and findings.

Can my old dentist send my X-rays to a new office?

Usually, yes. The Canadian Dental Association encourages dentists to obtain a new patient's existing X-rays rather than routinely taking new ones. Your new dentist may still need some images if the old ones are outdated or do not show the area in question.

Is it safe to get a dental X-ray while pregnant?

Tell the team first. Health Canada says radiation to the fetus from dental X-rays is extremely low when the abdomen is not directly exposed, but routine images are often deferred until after pregnancy. Essential images for pain or infection may still be taken, kept to the minimum needed.

Next step

If you have questions about the X-rays recommended for you or your child, learn about digital dental imaging at Landmark Dental Care. To book an exam or ask about transferring your records, call 902-893-2919 or contact the office. The practice is at 125 Queen St, Truro, open Monday to Friday, 8:30am to 5:00pm.

References

• American Dental Association: X-Rays/Radiographs
• Canadian Dental Association: Control of X-Radiation in Dentistry
• Health Canada: Radiation Protection in Dentistry — Safety Code 30
• ADA/FDA: Dental Radiographic Examinations — Recommendations for Patient Selection and Limiting Radiation Exposure (PDF, 2012)
• American Dental Association: Updated recommendations to enhance radiography safety in dentistry (2024)
• Government of Nova Scotia: Children's Oral Health Program

This article provides general educational information and is not a diagnosis or a substitute for care from a dentist or other qualified health professional.