Types of Extraoral X-Rays

    There are several types of extraoral X-rays that your dentist may take.
      Panoramic X-raysshow 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.
      Tomogramsshow a particular layer or "slice" of the mouth while blurring out all other layers. This type of 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 projectionsshow 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.
Sialographyinvolves 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 Sjögren'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 may be performed in a hospital or radiology center rather than a dentist's office, is used to identify problems in the bones of the face, such as tumors or fractures. CT scans are also used to evaluate bone for the placement of dental implants and difficult extractions. This helps the surgeon avoid possible complications during and after a surgical procedure.