Posts for tag: x-rays
The CAT scan is a relatively recent technique in dentistry, used to get an image of what’s happening deep within your jaws. You may be wondering what a CAT scan tells us that a conventional x-ray picture does not, and whether it is worth the extra expense to get one. And how does a CAT scan compare with a conventional x-ray in terms of radiation exposure?
CAT stands for “computer assisted tomography.” Often it’s just called a CT scan, for “computerized tomography.” The word “tomography” comes from roots meaning “slice” and “write.” Tomographic techniques take repeated two dimensional pictures, similar to repeatedly slicing through an object, and then assembles them with a computer to produce a three dimensional (3-D) image.
The latest type of CT scan used in dentistry is called CBCT, or Cone Beam Computed Tomography. The Cone Beam refers to a spiral beam of x-rays, which is used to create a series of two dimensional images from which a computer creates a 3-D image. Such an image is of great value in assessing problems and planning treatment.
Here are just a few examples of how a CBCT scan can be used. Orthodontists can see skeletal structures and developing teeth that are still inside the jawbone while planning strategies for directing the teeth in order to arrive at a better bite. Oral surgeons can find impacted or missing teeth, see their locations, and view their proximity to nerves and sinuses, assisting them in planning surgeries. These scans are particularly useful for root canal specialists because they show root canals that are less than a millimeter wide and even reveal accessory canals that may not be visible on conventional x-rays. In cases of sleep disorders such as sleep apnea, a CBCT during sleep can be used to view a person’s airway and how it may be blocked by the tongue and other soft tissues in a person’s throat during sleep.
Compared to background radiation, the amount of radiation delivered in dental x-rays is minimal. A CBCT delivers a dose of radiation that is less than a typical full mouth x-ray series but more than a typical two dimensional panoramic radiograph. Generally CBCT scanners deliver lower doses than medical CT scanners.
With one low-dose CBCT scan, we can get an accurate idea of the internal structure of your bones and teeth and how they are situated in relation to each other. Prior to the availability of such images, many of these relationships had to be discovered in the course of a surgery or other treatment. Thus such a scan can aid greatly in the quality of treatment you will receive.
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.”