Posts for tag: x-rays
One of the most widely used forms of dental imaging is the bitewing x-ray. So called because of the shape of the device that holds the exposable film a patient clenches between their back teeth, the bitewing x-ray is an effective means for detecting the earliest stages of tooth decay.
These early signs are small lesions on a tooth surface caused by mineral loss in the enamel. While we can identify them on front teeth through visual examination or bright lighting, they’re nearly impossible to see on the biting surfaces of back teeth. The bitewing x-ray solves this problem.
During the procedure, a narrow beam of x-rays is directed at the back teeth area. Since X-rays can transmit through solid matter, they pass through the teeth and gums to expose the film attached to the bitewing assembly.
X-rays pass through matter at different rates depending on the density of the tissue — a slower rate for harder tissues like teeth and bone and a faster rate for soft tissues like the gums. As a result, x-rays through teeth expose less of the film and appear as a lighter image than the gums. This difference is so precise even a tooth’s softer dentin appears slighter darker than its harder outer enamel.
This precision helps us identify decay lesions. Because the lesions on the enamel are less dense than the normal enamel, they’ll appear as dark spots. By detecting them at this stage we have a better chance for reversing the effects of decay or at least minimizing damage that’s already occurred.
Because x-rays emit radiation, there’s a natural concern about over-exposure and we go to great lengths to reduce it. Children may undergo a bitewing x-ray twice a year for developing teeth, while adults with healthy teeth are typically x-rayed just once a year. Advances in digital film and other technology have also helped lower the exposure rate.
Today’s standard 4-film bitewing x-ray produces about four days worth of what we receive on average from normal background radiation, so the health risk is quite negligible. The benefit, on the other hand, is much greater — the early detection of tooth decay could ultimately save a tooth.
X-rays are an important diagnostic tool in dentistry because of their ability to penetrate and pass through body tissues. Because they penetrate at different speeds depending on tissue density (shorter and thus darker on exposed film for soft tissues, longer and lighter for hard tissues like bone or teeth), we’re able to detect decay which appear as dark areas on x-ray film.
Without x-rays, the early detection and diagnosis of dental problems would be quite difficult. But despite its obvious benefits, it’s still a form of released energy that exposes patients to a certain amount of radiation. Since the potential health risk from radiation depends on the amount released (the dosage) and for how long and often a person is exposed, we must determine if the dosage and frequency from dental x-rays is a cause for concern.
It’s a common misconception to view any radiation exposure as dangerous. The truth is, however, we’re all exposed daily to radiation from the natural environment — about 2 to 4.5 millisieverts (the dosage measurement for radiation exposure) a year, or about 10 microsieverts (one-thousandth of a millisievert) every day.
In comparison, radiation exposure from routine dental x-rays is a fraction of this if measured over time. A set of four bitewing images of the back teeth produces 4 microsieverts of radiation, less than half the average daily exposure. One of the most comprehensive x-ray sets, a full mouth series of 18-20 images using “D” speed film, results in an exposure of 85 microsieverts, equaling about a week of normal radiation exposure.
These thoroughly researched rates help demonstrate that regular dental x-rays are relatively safe. What’s more, x-ray technology has continued to advance since first used in the mid-20th Century. With innovations in film and digital processing, today’s equipment produces only 80% of the radiation exposure of earlier machines. In effect, we’ve increased our capabilities to more accurately detect and diagnose issues through x-rays, while lowering the amount of radiation exposure.
Of course, a person’s annual exposure rate may differ from others. If you have concerns for yourself or your family about x-ray radiation exposure, please feel free to discuss this with us. Our primary goal is to improve your oral health without undue risk to your health in general.
If you would like more information on x-ray diagnostics and safety, please contact us or schedule an appointment for a consultation. You can also learn more about this topic by reading the Dear Doctor magazine article “X-Ray Frequency and Safety.”