Types of X Rays

By  , Expert Content
Feb 24, 2011

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There are two categories of oral X-rays:

  • Intraoral: In intraoral X-rays the X-ray film is placed inside the mouth;
  • Extraoral: In extraoral X-rays the X-ray film is placed outside the mouth

Intraoral radiographs

Intraoral X-rays are often taken by the dentist. A person who regularly visits the dentist for oral problems would have had many sets of intraoral radiographs and will probably have many more. 


These X-rays give a high level of detail of the oral structures. They help a dentist to identify;

  • Dental caries,
  • See the tooth roots,
  • Check the condition of the bony area around the tooth,
  • Check the status of developing teeth,
  • Monitor overall tooth health.

There are various types of intraoral X-rays. These help to look at different aspects of the teeth. Your dentist may recommend Bite-wing X-rays, Periapical X-rays, a "full-mouth radiographic survey," or FMX, Occlusal X-rays, depending on what he or she wants to look at.


These X-rays show different views of the intraoral structures.

  • Bite-wing X-rays: It emphasizes on the crowns of the teeth.
  • Periapical X-rays: Show the entire tooth.
  • Full-mouth radiographic survey or FMX: Shows all the teeth from crown to root to supporting structures.
  • Occlusal X-rays: Magnify the tooth size and emphasize tooth development and placement.

Digital radiographs are done by a new type of machines which is expensive. In this type of X-ray there is no X-ray film but an electronic pad or sensor is used. The image formed is sent directly to a computer on which the image appears on the screen. The image can be stored in the computer or printed out as required. This technology has several advantages over a standard X-ray.


Extraoral radiographs

In extraoral X-rays the X-ray film is placed outside the mouth. These X-rays give the detail of the teeth, but their focus is on the jaw or skull. They help a dentist to;

  • Monitor the growth and development of the jaw and teeth
  • Look at the position of impacted teeth,
  • View the relationship between teeth and jaws
  • Inspect the temporomandibular joint or other bones of the face.

The extraoral X-rays do not give the details of the teeth, and cannot be used to detect caries or problem in a tooth.

Panoramic radiographs: It shows all teeth and both upper and lower jaws in a single X-ray. It has to done by a special panoramic X-ray machine.

Tomograms: It is a special type of radiograph. It allows visualizing one particular layer of the tooth or jaw while blurring out all other layers. The structures or details that may be difficult to visualize on a standard X-ray can be seen on a tomogram such as the temporomandibular joint, the condyle that is a part of the joint.

Cephalometric projections: Show the entire side of the head and focus on the teeth in relation to the jaw and the profile of a person. Your orthodontists may recommend cephalometric projections to determine the best way to align the teeth according to the size of the teeth and jaws.

Sialography: This is used to see the salivary glands on a radiograph, as soft tissues, such as the gums and salivary glands can't be seen on an X-ray. In this special type of X-ray a radiopaque contrast material is directly injected into the salivary glands. The dye is seen on the film which shows the salivary gland and problems in it such as blockage, Sjögren's disease.

Computed tomography scan (CT scan): It shows three-dimensional image of the...

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