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.
For decades, dental x-rays have helped us accurately diagnose and treat a wide array of dental diseases and conditions. But even with recent advances in digital imaging, the traditional x-ray does have one drawback: its two-dimensional view doesn’t always provide the “big picture” that a three-dimensional viewpoint can provide.
But a new type of x-ray technology can do just that: known as cone beam computed tomography (CBCT), these machines record hundreds of digital images as a cone-shaped beam of x-ray energy is projected through a device that rotates around a person’s head. A computer then assembles the images into a single three-dimensional image that can be manipulated on screen to view from various angles. Not only does this provide greater context and detail, it does so with no more radiation exposure than a standard 20-film digital full-mouth x-ray series.
While CBCT hasn’t replaced the traditional x-ray, it’s making its mark in a number of specialized areas of dentistry. The following are just a few of the ways CBCT is improving both accuracy and treatment outcomes.
Orthodontics. CBCT can provide a much more detailed view of the entire jaw; this can help us determine the best locations for realigning teeth safely and effectively.
Dental Implants. With a CBCT scan we can precisely locate nerve canals, sinuses and adjacent teeth before implant surgery to locate the best position for the implant.
TMD Treatment. To help develop the best treatment approach for alleviating the pain and dysfunction of temporo-mandibular joint disease (TMD), a CBCT scan can provide us detailed information on how the disease is affecting a patient’s joints, teeth, sinuses and airway.
Impactions. An impacted tooth can exert damaging pressure against the roots of neighboring teeth. A CBCT scan allows us to observe the impacted tooth from various vantage points to determine the best treatment approach for neighboring teeth, nerve canals and sinuses.
If you would like more information on CBCT technology, 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 “Getting the Full Picture With Cone Beam Dental Scans.”
Your dental care would be much more limited without our ability to see “below the surface” with x-ray imaging. But since x-rays passing through the body are a form of radiation, could your exposure from them be hazardous to your health?
It depends on exposure dosages and, of course, the amount you have been exposed to over your lifetime. But, decades of research have demonstrated that exposure to dental x-rays during your regular office visits are only a fraction of the radiation you normally encounter from the natural environment every year.
X-rays have the ability to pass through body tissues, but at different rates for soft tissue like skin and muscle and hard tissue like bone. This effect creates shadows on exposed film; the differentiation is in such detail that a trained technician can interpret not only internal structures, but defects such as fractured bone or, in the case of dentistry, signs of tooth decay and bone loss from gum disease.
But like other energy sources in our environment, x-rays do emit radiation that in high doses can be dangerous to living tissue. The amount of exposure is measured in millisieverts (mSv), a unit that allows for comparison of doses from different sources of radiation. Scientists have calculated that we’re normally exposed to between 2 and 4.5 mSv every year.
By contrast, a single digital periapical image taken of a tooth is equal to 1 microsievert (μSv), or one thousandth of an mSv; a full mouth series (between 18 and 20 images) creates an exposure of 85 μSv, or 85/1000 of one mSv. In addition, advances in technology have further reduced the radiation exposure from x-ray imaging. For example, digital imaging has reduced exposure during full mouth x-rays from seven to ten days of equal exposure from normal background radiation to half a day, and with no loss in image quality.
In effect, dental x-rays pose little to no risk for patients. Still, understanding that x-ray imaging does expose patients to radiation, dentists follow certain protocols and safety precautions. For example, dentists will place a lead apron around their patients’ chest area during an x-ray exposure.
As your dentist, we’re happy to address any concerns you may have about x-ray radiation exposure. But rest assured, the x-ray devices used in your dental care, so necessary in the fight against tooth decay and other diseases, are safe and reliable.
If you would like more information on the use of x-ray technology 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.”