Dental X-rays

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

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

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

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.

Panoramic X-rays

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

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

Also known as CT scanning, computed tomography shows 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.

Digital X-Rays

Digital imaging, or digital radiography, is a valuable diagnostic tool frequently used in dentistry, as well as other disciplines. It is an innovative technique that uses a computer to efficiently manipulate and store X-ray images. Using this technology provides immediate results, readily available for sharing and discussion with patients and with other medical or dental professionals.

Uses of Digital Imaging

Since X-rays are always a part of comprehensive preventative and curative dental treatment, digital imaging is especially helpful in this field. As an objective means of delivering visual information, digital imaging assists in:

Detecting cavities

  • Implementing cosmetic treatments such as tooth whitening
  • Evaluating results of treatments for plaque and gingivitis
  • Measuring for endodontic procedures
  • Measuring for surgical implantations
  • Digital imaging is also important and effective in tracking the progress of orthodontic treatment.

Benefits of Digital Imaging

X-rays have long been considered an important part of dental care. The new technology that enables dentists to use digital X-rays has several advantages over traditional X-rays. These include:

  • Immediate diagnostic results
  • Reduced radiation exposure
  • Electronic storage of data
  • High quality image production
  • While exposure to dental X-rays has generally been considered safe, digital X-rays reduce the patient's radiation exposure by more than 50 percent.

The accelerated speed of the digital process, in which the need for a darkroom and chemical processing is unnecessary, is especially important during surgical procedures when time is of the essence. When digital X-rays are taken, usable images are available within seconds, rather than minutes.

While the images produced during digital imaging are considered clear and readable, there is some debate about the clarity of digital versus film images.

Additional Resources

Louisa Gallegos, DDS, MSD Prosthodontist

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