Dental X-rays are a vital part of a dental examination. There are two main types of dental X-rays: those taken with the X-ray film inside the mouth (intraoral) and those taken with the X-ray film outside the mouth (extraoral). Intraoral X-rays are the ones most commonly used. They provide detailed evidence of the growth of developing teeth, the health of tooth roots and surrounding bone, including the jaw. They also help the dentist zero in on any cavities. Extraoral X-rays, while they also show the teeth, primarily focus on the jaw and skull. They are therefore more helpful in diagnosing malocclusions, impacted teeth, and possible temporomandibular joint disorders (TMD).
Types of Intraoral X-Rays
There are three types of intraoral X-rays. Each type helps the dentist visualize a different aspect of the tooth.
Bite-wing X-rays, named for the fact that the patient bites down on the film, provide details of both the upper and lower teeth in one section of the mouth. Since each one visualizes an entire tooth, bite-wings are used to evaluate changes in bone density that may result from gum disease and to detect decay. These X-rays are also valuable when the dentist wants to fit a crown or check on the integrity of fillings.
Periapical X-rays focus on fewer teeth, but show each entire tooth, from the crown to the root. They include images of any abnormalities of the root or surrounding jaw bone.
Occlusal X-rays are larger than most other X-rays, and are most often used to track tooth development and location in children. Because these X-rays show the entire arch of the upper or lower teeth in the jaw, they help the dentist to evaluate possible bite problems.
Types of Extraoral X-Rays
There are many types of extraoral X-rays. Each has a somewhat different purpose.
These X-rays take images of the whole mouth at once, showing all the upper and lower teeth at one time. Panoramic X-rays show positions of developing, fully erupted, or impacted teeth and are also helpful in diagnosing tumors.
Tomograms are designed to highlight a particular layer of the mouth that might otherwise be obscured by adjacent layers. These X-rays focus on the desired image and intentionally blur those that are in the way of the targeted structure.
Cephalometric projections provide an image of the entire side of the head, presenting views of the teeth in relation to the jaw. These X-rays are useful to orthodontists as they develop treatment plans to correct malocclusion.
Sialography enables the dentist to visualize the salivary glands. In order for the procedure to take place, the patient is injected with a dye that allows the salivary glands to be seen on X-ray. This type of X-ray is used to detect blockages of the salivary glands or to investigate conditions such as Sjögren's syndrome.
Computed Tomography (CT scanning) is a more complex type of X-ray, showing images of internal structures in three dimensions. This variety of X-ray, sometimes used to evaluate problems of the bones of the face, including fractures or tumors, is also employed to evaluate precise locations for dental implants and complex tooth extractions.
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- National Institutes of Health
- National Institute of Dental and Craniofacial Research
- Centers for Disease Control and Prevention
- Eunice Kennedy Shriver National Institute of Child Health and Human Development
- U.S. Department of Health & Human Services
- U.S. National Library of Medicine