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.
It’s important for your child’s current and future health that we watch out for tooth decay. Taking x-rays is a critical part of staying one step ahead of this common disease.
But while x-ray imaging is commonplace, we can’t forget it’s still a form of radiation that could be potentially harmful, especially for a child whose tissues are rapidly developing. We must, therefore, carefully weigh the potential benefits against risk.
This concern has given birth to an important principle in the use of x-rays known as ALARA, an acronym for “As Low As Reasonably Achievable.” In basic terms, we want to use the lowest amount of x-ray energy for the shortest period of time to gain the most effectiveness in diagnosing tooth decay and other conditions.
A good example of this principle is a common type of radiograph known as a bitewing. The exposable x-ray film is attached to a plastic devise that looks like a wing; the patient bites down on it to hold it in place while the x-ray exposure takes place. Depending on the number of teeth in a child’s mouth, an appointment usually involves 2 to 4 films, and children are typically spaced at six months apart. Frequency of x-rays depends on your child’s tooth decay risk: lower risk, less need for frequent intervals.
Each bitewing exposes the child to 2 microsieverts, the standard unit for radiation measurement. This amount of radiation is relatively low: by contrast, we’re all exposed to 10 microsieverts of background radiation (natural radiation occurring in the environment) every day or 3,600 microsieverts annually. Even two appointments of four bitewings each year is a fraction of a percent of the background radiation we’re exposed to in the same year.
This conservative use of x-rays is well within safe parameters for children. As x-ray technology continues to advance (as with the development of digital imaging) we anticipate the exposure rate to diminish even more. Prudently used, x-rays remain one of our best tools for ensuring your child’s teeth are healthy and developing normally.
If you would like more information on the use of x-rays with children, 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 Safety for Children.”