Panoramic x-rays

Dental Radiographs (x-rays)

What are the benefits of a dental radiograph examination?
How safe are dental x-rays?

What are the benefits of a dental radiograph examination?
Many diseases of the teeth and surrounding tissues cannot be seen during a routine visual examination of your mouth.

An x-ray examination may reveal:

  • small areas of decay between the teeth or below existing restorations (fillings)
  • infections in the bone
  • periodontal (gum) disease in the form of reduced bone levels around the teeth
  • abscesses or cysts
  • developmental abnormalities
  • some types of tumors

Finding and treating dental problems at an early stage can save time, money and unnecessary discomfort. If you have a hidden tumor, radiographs may even help save your life.

There are two types of radiographs that me taken: intra-oral and extra-oral. The intraoral x-rays are the most commonly known type that involve the placement of the small films inside the mouth, and provide the most detail and accuracy of small areas at a time. The extraoral films are larger, and take a more overall view of the teeth and jaws. The most common extraoral film is the panoramic x-ray which is taken by a unit that spins around the patients head and produces a complete survey of the teeth and upper & lower jawbones.



How safe are dental x-rays?
Just the mention of the word “radiation” conjures up an unpleasant image for most people. We associate it with bombs, cancer, and all manner of other bad things. But do you know that there are many beneficial uses of radiation? One type of radiation, x-rays, are used extensively in the medical and dental professions to diagnose and treat a wide variety of conditions.

Just how much radiation do you get from a dental x-ray and how harmful is it? First, let’s talk about what an x-ray is. X-rays are energy in the form of waves, identical to visible light. In fact, the only difference between light and x-rays is that light doesn’t have enough energy to go through your body and x-rays do. Both can make an image on photographic film, so both types of energy are used to make pictures; light makes photographs of the “outside” of objects, x-rays make pictures of the “inside” of objects, including your body.

A unit called a “rem” is used to measure radiation. A rem is a large unit, much like a mile is a large unit of length, so we usually use a millirem (mrem) instead, much as you would measure in inches instead of miles for most purposes. (It takes 1000 mrem to equal one rem.)

Advances in x-ray equipment, especially film technology, allows dentists to get a good x-ray image using much less radiation than was previously required. A typical dental x-ray image exposes you to less than 1 mrem. The U.S. Council on Radiation Protection (NCRP) says that the average resident of the U.S. receives about 360 mrem every year from background sources. This comes from outer space, radioactive materials in the earth, and small amounts of radioactive material in most foods we consume.

Some typical sources that may expose you to radiation also include smoke detectors (less than 1 mrem per year), living in a brick house instead of a wood one (about 10 mrem per year due to radioactive materials in the masonry), cooking with natural gas (about 10 mrem per year from radon gas in the natural gas supply), reading a book for 3 hours per day (about 1 mrem per year due to small amounts of radioactive materials in the wood used to make the paper), and even from flying in an airplane (about 5 mrem for one cross-country flight because of the increased altitude.) In fact, you receive about 2 mrem per year from sleeping next to someone! This is because all of us have very small amounts of naturally occurring radioactive materials in our bodies.

Obviously, you probably would not refuse to fly on an airplane, live in a brick house, read books, live without smoke detectors, or sleep with your spouse because of the small amount of radiation you receive from these activities.

In comparison to x-rays used in medicine, the dental patient exposures used to take intraoral and panoramic views are quite small because of their smaller size of film and limited portion of body exposed. Below is a partial list of common x-ray views and their associated doses of radiation (in Millirems):

Mammography                                   1000      Gallbladder                 168    
Lower Gastrointestinal (GI) series         875       Skull                            78    
Upper Gastrointestinal (GI) series         595       Femur                          21    
IV Pyelogram (kidneys/bladder)            420       Dental (panoramic)          1    
Ribs                                                  143       Dental (intraoral)          0.5    

It would therefore take 1750 dental x-rays to equal the amount of radiation from one lower GI series.