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Types of Intraoral and Extraoral Dental X-Rays

There are two main types of dental X-rays: intraoral (meaning the X-ray film
is inside the mouth) and extraoral (meaning the X-ray film is outside the
mouth).

  • Intraoral X-rays are the most common type of dental X-ray
    taken. These X-rays provide a lot of detail and allow your dentist to find
    cavities, check the health of the tooth root and bone surrounding the tooth,
    check the status of developing teeth, and monitor the general health of your
    teeth and jawbone.
  • Extraoral X-rays show teeth, but their main focus is the
    jaw and skull. These X-rays do not provide the detail found with intraoral
    X-rays and therefore are not used for detecting cavities or for identifying
    problems with individual teeth. Instead, extraoral X-rays are used to look for
    impacted teeth, monitor growth and development of the jaws in relation to the
    teeth, and to identify potential problems between teeth and jaws and the
    temporomandibular joint (TMJ, see document, “Temporomandibular disorders” for more information) or other
    bones of the face.

Types of Intraoral X-Rays

There are several types of intraoral X-rays, each of which shows different
aspects of teeth.

  • Bite-wing X-rays show details of the upper and lower teeth
    in one area of the mouth. Each bite-wing shows a tooth from its crown to about
    the level of the supporting bone. Bite-wing X-rays are used to detect decay
    between teeth and changes in bone density caused by gum disease. They are also
    useful in determining the proper fit of a crown (or cast restoration) and the marginal integrity of fillings.
  • Periapical X-rays show the whole tooth — from the crown
    to beyond the end of the root to where the tooth is anchored in the jaw. Each
    periapical X-ray shows this full tooth dimension and includes all the teeth in
    one portion of either the upper or lower jaw. Periapical X-rays are used to
    detect any abnormalities of the root structure and surrounding bone
    structure.
  • Occlusal X-rays are larger and show full tooth development
    and placement. Each X-ray reveals the entire arch of teeth in either the upper
    or lower jaw.

Types of Extraoral X-Rays

There are several types of extraoral X-rays that your dentist may wish to
take.

  • Panoramic X-rays show the entire mouth area — all the
    teeth in both the upper and lower jaws — on a single X-ray. This type of X-ray
    is useful for detecting the position of fully emerged as well as emerging
    teeth, can identify impacted teeth and aid in the diagnosis of tumors.
  • Tomograms show a particular layer or “slice” of
    the mouth while blurring out all other layers. This type of X-ray is useful for
    examining structures that are difficult to clearly see — for instance, because
    other structures are in very close proximity to the structure to be
    viewed.
  • Cephalometric projections show the entire side of the
    head. This type of X-ray is useful for examining the teeth in relation to the
    jaw and profile of the individual. Orthodontists use this type of X-ray to
    develop their treatment plans.
  • Sialography involves visualization of the salivary glands
    following the injection of a dye. The dye, called a radiopaque contrast agent,
    is injected into the salivary glands so that the organ can be seen on the X-ray
    film (the organ is a soft tissue that would not otherwise be seen with an
    X-ray). Dentists might order this type of test to look for salivary gland
    problems, such as blockages or Sjogren‘s syndrome.
  • Computed tomography, otherwise known as CT scanning, shows
    the body’s interior structures as a three-dimensional image. This type of
    X-ray, which is performed in a hospital rather than a dentist’s office, is used
    to identify problems in the bones of the face, such as tumors or
    fractures.

In the Pipeline

There’s a newer X-ray technique that your dentist already may be using or
may soon be using. It’s called digital imaging. Instead of developing X-ray
film in a dark room, the X-rays are sent directly to a computer and can be
viewed on screen, stored, or printed out. There are several nice benefits of
using this new technology including:

  • The technique uses less radiation than the typical X-ray and there is no
    wait time for the X-rays to develop — the images are available on screen a few
    seconds after being taken.
  • The image taken, of a tooth for example, can be enhanced and enlarged many
    times it’s actual size on the computer screen, making it easier for your
    dentist to show you where and what the problem is.
  • If necessary, images can be electronically sent to another dentist or
    specialist — for instance, for a second opinion on a dental problem — to
    determine if a specialist is needed, or to a new dentist (if you move).
  • Software added to the computer can help dentists digitally compare current
    to previous images in a process called subtraction radiography. Using this
    technique, everything that is the same between two images is “subtracted
    out” from the image leaving a clear image of only the portion that is
    different. This helps dentists easily see the tiniest changes that may not have
    been noticed by the naked eye.

Reviewed by the doctors at The Cleveland Clinic Department of Dentistry.

Reviewed by Jay H. Rosoff, DDS, on March 1, 2007

Edited by Charlotte E. Grayson Mathis, MD, on May 1, 2005

Portions of this page © The Cleveland Clinic 2000-2005

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