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Digital Dental Radiography: Zooming in on the Future of Dental Imaging

Dental professionals today are increasingly using digital dental radiographs (digital X-rays) to better detect, diagnose, treat, and monitor oral conditions and diseases.

Digital radiography is a type of X-ray imaging that uses digital X-ray sensors to replace traditional photographic X-ray film, producing enhanced computer images of teeth, gums, and other oral structures and conditions.

Digital dental images are acquired through three methods: the direct method, indirect method and semi-indirect method. The direct method uses an electronic sensor placed in the mouth to record images. The indirect technique uses an X-ray film scanner to view traditional dental X-rays as digital images. The semi-indirect digital technique combines a sensor and scanner to convert dental X-rays into digital film.

Types and Uses of Digital Dental Radiographs

Digital dental radiographs can be taken inside (intraoral) or outside (extraoral) the mouth. Intraoral X-rays, the most commonly taken dental X-ray, provide great detail and are used to detect cavities, check the status of developing teeth and monitor teeth and bone health. Extraoral X-rays do not provide the detail of intraoral X-rays and are not used to identify individual tooth problems. However, they are used to detect impacted teeth, monitor jaw growth and development, and identify potential problems between teeth, jaws and temporomandibular joints (TMJ), or other facial bones.

Types of intraoral X-rays include:

  • Bitewing X-rays, which are taken with the patient biting down on film, show details of the upper and lower teeth in one area of the mouth. Each bitewing shows a tooth from its crown (top) to about the level of the supporting bone. Bitewing X-rays are used to detect decay between teeth and changes in bone density caused by gum disease, as well as to determine the fit of dental crowns or restorations, and the marginal integrity of tooth fillings.
  • Periapical (limited) X-rays show the whole tooth from the crown to beyond the root tips to the supporting bone in one area of either the upper or lower jaw. Periapical X-rays are used to detect root structure and surrounding bone structure abnormalities. Showing bone loss around each tooth, periapical X-rays aid in treating conditions such as periodontitis, advanced gum disease, and detecting endodontic lesions (abscess).

Types of extraoral X-rays include:

  • Panoramic (Panorex) X-rays, which require a machine that rotates around the head, show the entire mouth, including all the teeth in the upper and lower arch, in one image. Panoramic X-rays are used to plan treatment for dental implants, detect impacted wisdom teeth and jaw problems, and diagnose bony tumors and cysts. Panoramic films are used for forensic and legal purposes to identify otherwise unrecognizable bodies after fires, crashes or other fatalities.
  • Multi-slice computed tomography (MCT) shows a particular layer or “slice” of the mouth while blurring all other layers. This type of X-ray is useful for examining structures that are difficult to see clearly.
  • Cephalometric projections, which show the entire head, help examine teeth in relation to a patient’s jaw and profile. Orthodontists, specialists in aligning and straightening teeth, use cephalometric projections to develop their treatment plans.
  • Sialography uses a dye (radiopaque contrast agent) injected into the salivary glands to visualize them on the X-ray film. A sialography typically is used to identify salivary gland problems, such as blockages or Sjogren’s syndrome, an autoimmune disease that impedes saliva and tear production.
  • Cone beam computerized tomography (CBCT) shows the body’s interior structures as a three-dimensional image. CBCT — often performed in a hospital or imaging center, but increasingly being used in the dental office — is used to identify facial bone problems, such as tumors or fractures. CT scans also are used to evaluate bone for dental implant placement and difficult tooth extractions to avoid possible complications during and after surgical procedures.

The CBCT, which requires up to eight times more radiation than panoramic radiographs, does not slice images. Instead, its cone-shaped beam scans both the upper and lower mouth areas at once. The data is captured by a two-dimensional array and creates high-resolution images, which are then combined to form a 3-D image of the bony structures.

Benefits of Digital Dental Radiography

Benefits of digital dental radiographs compared to traditional dental X-rays include the following:

  • Digital radiographs reveal small hidden areas of decay between teeth or below existing restorations (fillings), bone infections, gum (periodontal) disease, abscesses or cysts, developmental abnormalities and tumors that cannot be detected with only a visual dental examination.
  • Digital radiographs can be viewed instantly on any computer screen, manipulated to enhance contrast and detail, and transmitted electronically to specialists without quality loss.
  • Early detection and treatment of dental problems can save time, money and discomfort.
  • Digital micro-storage technology allows greater data storage capacity on small, space-saving drives.
  • Dental digital radiographs eliminate chemical processing and disposal of hazardous wastes and lead foil, thereby presenting a “greener” and eco-friendly alternative.
  • Digital radiographs can be transferred easily to other dentists with compatible computer technology, or photo printed for dentists without compatible technology.
  • Digital sensors and PSP (photostimulable phosphor) plates are more sensitive to X-radiation and require 50 to 80 percent less radiation than film. This technology adheres to the ALARA (As Low As Reasonably Achievable) principle, which promotes radiation safety.
  • Digital radiograph features, including contrasting, colorizing, 3-D, sharpness, flip, zoom, etc., assist in detection and interpretation, which in turn assist in diagnosis and patient education. Digital images of problem areas can be transferred and enhanced on a computer screen next to the patient’s chair.
  • Digital dental images can be stored easily in electronic patient records and, sent quickly electronically to insurance companies, referring dentists or consultants, often eliminating or reducing treatment disruption and leading to faster dental insurance reimbursements.

Disadvantages of Digital Dental Radiographs

Digital radiograph start-up costs are expensive for dentists, with conservative estimates ranging from $11,000 to $15,000 for a wired sensor system (not including the cost for computers, software, and additional hardware, such as servers), to $20,000 to $50,000 for a wireless system, not including maintenance and service repairs. Most practices have more than one sensor, and there also is a cost associated with personnel hours to convert old records to digital.

Implementing digital radiography in a dental practice requires additional training that must be periodically updated to account for existing technology that quickly becomes obsolete or unavailable. The lack of universal digital dental radiography use is another disadvantage.

Additional disadvantages of digital dental radiographs include the following:

Sensor size: Some direct systems sensors are thicker and bulkier than dental films, causing patient discomfort, especially for those prone to gagging. Digital sensors are smaller than standard film, so they show less image areas.

Fragility: Thinner than film plates, PSP plates are more prone to damage from bending, often necessitating frequent replacements.

Infection control: Most digital sensors and PSP plates can’t be sterilized and therefore require protective plastic barriers that must be changed between patients to prevent cross contamination and infection.

Special Training

Dentists, dental hygienists, dental assistants and oral/maxillofacial radiologists may take digital radiographs after completing special training. Radiographic training requirements for dental office personnel frequently differ from and are less stringent than those for medical X-ray personnel and are found in state dental practice acts or dental board regulations. Required training considerations include periodic safety updates and availability of and training in new equipment, supplies and techniques; infection control procedures; and continuing education in the proper and safe use of radiation equipment.

Safety Considerations

While radiation exposure is low with digital radiographs, no one should receive more radiation than absolutely necessary. Protective lead aprons and thyroid collars should be used, especially for pregnant women, women of childbearing years and children.

It is safe for pregnant women to have up to four radiographs per office visit, although most patients and doctors will elect to delay radiographs until the pregnancy is over. There should be no concerns for a pregnant woman to have an X-ray taken in an emergency situation. Precautions such as the use of “double lead aprons” cut radiographic exposure down to nearly immeasurable levels. Women who are breast-feeding or trying to become pregnant do not need to delay X-rays.