Digital dental X-rays (digital radiography) use an electronic sensor instead of traditional film to capture images of the teeth and surrounding structures. This technology instantaneously converts radiation exposure into a digital image displayed on a computer screen. These images provide a comprehensive look at what is not visible during a standard visual examination. They are used to diagnose interproximal decay, assess bone loss from periodontal disease, evaluate tooth root integrity, and identify developing or impacted teeth.
Digital technology offers several advantages over conventional film-based systems, including a significant reduction in patient radiation exposure (often 70% or more). It eliminates the need for toxic chemicals used in film development. The immediate display enhances the speed of diagnosis and allows for faster consultation. Electronic storage and transmission simplifies record-keeping and communication with specialists.
Essential Safety Measures and Equipment Setup
The procedure begins with meticulous preparation focused on minimizing radiation exposure, following the principle of ALARA (As Low As Reasonably Achievable). Patient safety requires the mandatory use of a lead apron with a thyroid collar to shield radiation-sensitive tissues outside the direct path of the X-ray beam. Before positioning the sensor, all metal objects in the path of the beam, such as glasses, removable dental appliances, or jewelry, must be removed to prevent artifacts.
The operator must maintain a safe distance during the brief exposure period, standing at least six feet away from the X-ray tube head and the patient. If this distance is not feasible, the operator must stand behind a protective barrier. Equipment readiness is confirmed by powering on the computer and opening the imaging software before the patient is seated.
Proper infection control dictates that the digital sensor or Phosphor Storage Plate (PSP) must be covered with a fresh, disposable plastic barrier sheath for every patient contact. Once the sensor is covered and connected, the X-ray unit’s exposure settings are selected based on the patient’s age, size, and the specific area being imaged. The precise selection of kilovoltage (kVp), milliamperage (mA), and exposure time is necessary to ensure the resulting image is neither too dark nor too light.
Intraoral Sensor Positioning Techniques
Intraoral imaging is categorized into three primary views, each designed to capture specific information about the oral cavity:
- Bitewing images show the crowns of the upper and lower teeth in a single view, optimal for detecting decay between the teeth and evaluating bone height.
- Periapical (PA) images capture the entire tooth, from the crown to the root tip (apex), along with the surrounding bone, necessary for diagnosing abscesses or pathology at the root end.
- Occlusal views use a larger sensor placed on the biting surface to image a broad area of the jaw, often used to visualize impacted teeth or large lesions.
Achieving a geometrically accurate image relies on the paralleling technique, which utilizes specialized instruments, such as Rinn or Extension Cone Paralleling (XCP) devices. These holders feature a bite block, an indicator arm, and an aiming ring, designed to position the sensor correctly within the mouth. The core principle of this technique is to position the sensor parallel to the long axis of the tooth being imaged.
The aiming ring ensures the central ray of the X-ray beam is directed perpendicular to both the tooth and the parallel sensor. This geometry minimizes distortion, preventing the teeth from appearing unnaturally elongated or foreshortened. For a maxillary molar bitewing, the sensor is oriented horizontally and placed toward the midline of the palate, parallel to the central grooves of the molars. The patient closes firmly onto the bite block, guiding the X-ray cone to the correct horizontal and vertical angulation.
Image Capture, Review, and Quality Assurance
Once the sensor is correctly positioned, the operator confirms the patient is still and steps behind the protective barrier before activating the X-ray beam. The exposure button is held down until the audible signal confirms the emission of radiation has ceased. A principal advantage of digital radiography is the instantaneous transfer of the image from the sensor to the computer screen.
The resulting digital image can be manipulated using imaging software to enhance its diagnostic quality. The operator can adjust the brightness and contrast, or use digital tools to zoom in, invert colors, or measure anatomical structures. This immediate visualization allows for a rapid assessment of the image quality before the patient is dismissed.
Quality assurance involves immediately checking for common technical errors that would necessitate a retake, exposing the patient to additional radiation.
Common Technical Errors
- A “cone cut” appears as a distinct opaque or white area, indicating the X-ray beam was not properly centered over the sensor.
- Incorrect vertical angulation results in either elongation (teeth appear stretched) or foreshortening (teeth look compressed).
- Horizontal angulation errors are identified by overlapping contacts between adjacent teeth, rendering the image useless for detecting interproximal decay.
If the image is diagnostically acceptable, it is saved to the patient’s electronic health record. The sensor is then immediately removed and disinfected according to strict infection control protocols.