Dental radiographs (also know as x-rays) are an important diagnostic tool that helps your dentist understand what’s going on inside your mouth. In addition to helping your dentist detect cavities, dental x-rays are a non-invasive way to peek beneath the surface of the gum line to locate teeth, examine the integrity of the roots, and to reveal bone loss.
Although x-rays rely on radiation to produce these images, that radiation is delivered at such low levels that it is considered to be very safe. You get as much radiation from flying in a plane or eating bananas as you do from a dental x-ray.
Even though x-rays are valuable and safe, your dentist will be cautious and conservative both in how and how often they are prescribed.
How do dental x-rays work?
Unlike a traditional photograph, which uses visible light to expose an image to film, x-rays rely on electromagnetic radiation. This radiation passes through soft tissue but is reflected by bones and teeth. An x-ray will therefore result in an image of these harder surfaces instead of the soft tissues of cheek and gums.
Conventional x-rays were created by using this radiation to expose film, but many dentists have switched to digital x-rays, which rely on sensors hooked up to a computer. Digital x-rays are faster and more comfortable, and need only a fraction of the radiation used by older film x-rays.
Dental x-rays reveal what can’t be seen
Your dentist can learn a lot from an x-ray image. There are areas of the mouth that just can’t be seen even with that bright light in your face and those little handheld mirrors. X-rays can reveal:
- Decay in the tight spaces between the teeth or below the gum line
- Decay inside the tooth (beneath a filling, for example)
- Bone loss from gum disease
- Changes over time due to tooth movement, decay, or bone loss
- The location of incoming teeth such as wisdom teeth
- Abnormalities such as cysts, tumors, and root resorption
X-rays are an important tool for exposing dental problems and planning treatment.
Once every two to three years might be enough
In the past, your dentist might have recommended x-rays every year. Current recommendations by the ADA, however, state that once every two to three years for therapeutic x-rays are probably all you need.
These therapeutic x-rays give your dentist a holistic view of the whole mouth, and an overview of any issues that might require more investigation.
In addition to these occasional therapeutic x-rays, diagnostic x-rays might sometimes be needed to focus on specific problem areas — a cracked tooth, for example, or a cavity that might need a root canal.
This limited use of x-rays delivers only minor doses of radiation
When therapeutic x-rays are limited to once every two to three years, and additional diagnostic x-rays are performed only as needed, a patient’s lifetime exposure to radiation at the dentist will be minuscule compared with natural radiation from other sources.
This radiation is measured in units of mrem. An older style dental film x-ray deliver 1mrem per image, while the newer digital dental x-rays deliver 0.1mrem per image — about as much as an airport security scan. Other sources of radiation deliver the following amounts:
| Soil | 35 mrem/year |
| Cigarette smoking | 1,300 mrem/year |
| Transcontinental flight | 2–4 mrem/flight |
| Drinking water | 5 mrem/year |
| Natural gas for heating and cooking | 9 mrem/year |
On average, Americans are exposed to 620 mrem per year in total, half of this coming from natural background radiation and half from man-made sources. Dental x-rays contribute only a small fraction of a percent to this total.
Extra safety precautions with dental x-rays
In spite of the small doses of radiation from a dental x-ray and the conservative approach taken to prescribing new x-rays, your licensed hygienist or dental assistant will also cover your body and neck with a lead shield and thyroid collar when images are taken. This keeps the radiation localized to just the area needed for imaging.
Dental x-rays for pregnant women and children
X-rays for pregnant women are considered to be safe by the American Dental Association and other health authorities. If you’re still concerned about harmful effects, it’s okay to put off x-rays during pregnancy. It’s not okay to put off oral care, though. An estimated 40% of women have gum disease during pregnancy, and a mother’s gum disease is far more likely than dental x-rays to harm a developing fetus.
There is some concern as to the safety of dental x-rays for children, whose bodies are still growing and may be more susceptible to damage from radiation. However, dental x-rays still deliver minimal radiation compared to natural sources. Pediatric dentists will take care to use x-rays only when needed. And once again, the damage from neglecting oral care outweighs the risk from dental x-rays.
