Dental x-rays are a type of image of the teeth and mouth. X-rays are a form of high energy electromagnetic radiation. The x-rays 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 that contain air will be black on the film. Teeth, tissue, and fluid will appear as shades of gray.
How the Test is Performed
The test is performed in the dentist's office. There are many types of dental x-rays. Some of them are:
- Bitewing. Shows the crown portions of the top and bottom teeth together when the person bites on a paper tab.
- Periapical. Shows 1 or 2 complete teeth from crown to root.
- Palatal (also called occlusal ). Captures all the upper or lower teeth in one shot while the film rests on the biting surface of the teeth.
- Panoramic. Requires a special machine that rotates around the head. The x-ray captures all of the 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.
Many dentists are also taking x-rays using digital technology. These images 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 before dental surgery, especially when many implants are being placed.
How to Prepare for the Test
There is no special preparation. A lead apron may be placed over your body. Tell your 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.
Normal 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 tooth decay (called cavities, or dental caries)
- Bone damage (such as from gum disease called periodontitis)
- Abscessed teeth
- Fractured jaw
- Problems in the way the upper and lower teeth fit togethher (malocclusion)
- Other abnormalities of the teeth and jaw bones
There is very low radiation exposure from dental x-rays. 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 before they are visible, even to the dentist. Many dentists will take yearly bitewings to look for early development of cavities.
X-ray - teeth; Radiograph - dental; Bitewings; Periapical film; Panoramic film; Digital image
Griffin N, Grant LA. Dental radiology. In: Griffin N, Grant LA, eds. Grainger & Allison's Diagnostic Radiology Essentials. New York, NY: Elsevier Churchill Livingstone; 2013:chap 7.9.
Parks ET, Aps JK. Radiographic techniques. In: Dean JA, ed. McDonald and Avery's Dentistry for the Child and Adolescent. 10th ed. St. Louis, MO: Elsevier; 2016:chap 2.
Review Date 2/22/2016
Updated by: Michael Kapner, DDS, general and aesthetic dentistry, Norwalk Medical Center, Norwalk, CT. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.