Dental x-rays

  • Definition
    • 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.

  • Alternative Names
    • X-ray - teeth; Radiograph - dental; Bitewings; Periapical film; Panoramic film; Digital image

  • 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 Results
    • 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
  • Risks
    • 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.

  • Considerations
    • 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.

  • References
    • 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.