Dental x-rays are a type of image of the teeth and mouth. X-rays are a form of high energy electromagnetic radiation. X-rays can penetrate the body to form an image on film.
Structures that are dense (such as silver fillings or metal restoration) will block most of the light energy from the x-ray. They will appear white on developed film. Structures containing air will be black on film, and teeth, tissue, and fluid will appear as shades of gray.
X-ray - teeth; Radiograph - dental; Bitewings; Periapical film; Panoramic film
How the Test is Performed
The test is performed in the dentist's office. There are many types of dental x-rays. Some are:
Palatal (also called occlusal)
The bitewing shows the crown portions of the top and bottom teeth together when the patient bites on a paper tab.
The periapical shows one or two complete teeth from crown to root.
A palatal or occlusal x-ray captures all the upper and lower teeth in one shot while the film rests on the biting surface of the teeth.
A panoramic x-ray requires a special machine that rotates around the head. The x-ray captures the entire jaws and teeth in one shot. It is used to plan treatment for dental implants, check for impacted wisdom teeth, and detect jaw problems. A panoramic x-ray is not the best method for detecting cavities, unless the decay is very advanced and deep.
In addition, many dentists are taking x-rays using digital technology. The image runs through a computer. The amount of radiation given off during the procedure is less than traditional methods. Other types of dental x-rays can create a 3-D picture of the jaw. Cone beam computerized tomography (CBCT) may be used prior to dental surgery, especially when multiple implants are being placed.
How to Prepare for the Test
There is no special preparation. Lead apron may be placed to cover the body. Tell the dentist if you might be pregnant.
How the Test will Feel
The x-ray itself causes no discomfort. Biting on the piece of film makes some people gag. Slow, deep breathing through the nose usually relieves this feeling.
Why the Test is Performed
Dental x-rays help diagnose disease and injury of the teeth and gums.
The x-rays show a normal number, structure, and position of the teeth and jaw bones. There are no cavities or other problems.
What Abnormal Results Mean
Dental x-rays may be used to identify the following:
- The number, size, and position of teeth
- Unemerged or impacted teeth
- The presence and extent of dental caries (cavities)
- Bone damage (such as from periodontitis)
- Abscessed teeth
- Fractured jaw
- Malocclusion of teeth
- Other abnormalities of the teeth and jaw bones
There is very low radiation exposure. However, no one should receive more radiation than necessary. A lead apron can be used to cover the body and reduce radiation exposure. Pregnant women should not have x-rays taken unless absolutely necessary.
Dental x-rays can reveal dental cavities (tooth decay) before they are visible, even to the dentist. Many dentists will take yearly bitewings for the early development of cavities.
Rout J, Brown JE. Dental and maxillofacial radiology. In: Adam A, Dixon AK, eds. Grainger & Allison's Diagnostic Radiology: A Textbook of Medical Imaging. 5th ed. New York, NY: Churchill Livingstone; 2008:chap 63.