A panoramic X-ray, often called a Pano, is a specialized two-dimensional dental image that captures the entire oral-maxillofacial area in a single shot. This technology provides a flattened view of the curved jaw structure, allowing dentists to see the full set of teeth, the upper and lower jaws, and surrounding anatomical areas. Unlike small films that focus on a few teeth, the Pano is used for a broad initial assessment of a patient’s overall dental and bone health.
Defining the Panoramic X-ray
The panoramic X-ray differs significantly from conventional dental radiographs, such as bitewings or periapical films, which require placing small sensors inside the mouth. The Pano employs a technique known as focal plane tomography, where the X-ray source and the digital sensor rotate simultaneously around the patient’s head. This coordinated movement focuses the image plane only on the jaw structures, creating a single, continuous picture of the entire mouth.
This rotational method is necessary because the jawbone forms a horseshoe shape, which cannot be captured clearly in a single static projection. The machine uses a narrow beam to scan the entire arc of the jaw, digitally compiling the data into one wide-view image. While providing a vast field of view, the Pano offers a general overview and does not produce the sharp, high-resolution detail of individual teeth that standard intraoral X-rays provide. Its primary utility lies in assessing structures and conditions that extend beyond the roots of the teeth.
The Examination Process
The process of taking a panoramic X-ray is straightforward and takes only a few moments, offering greater comfort compared to methods requiring sensors placed inside the mouth. The patient either stands or sits stationary in the center of the specialized unit, with their head positioned and stabilized using supports for the chin and forehead. To ensure proper alignment and separation of the upper and lower arches, the patient is asked to gently bite down on a small plastic bite-block.
Before the scan begins, patients must remove all metal objects, such as jewelry, eyeglasses, and hairpins, which could interfere with the X-ray beam and create artifacts on the final image. Once the patient is correctly positioned, the machine’s imaging arm rotates in a semi-circular path around the head. The entire scanning motion is quick, often lasting only 12 to 20 seconds, and the patient must remain completely still during this short period to prevent image distortion.
What the Image Reveals
The broad perspective offered by the panoramic X-ray is invaluable for identifying numerous conditions and structures that are not visible on smaller, localized films. The Pano is the standard tool for assessing the health and structure of the temporomandibular joints (TMJ), which connect the jawbone to the skull, helping to diagnose potential disorders or degenerative changes. This comprehensive view is also frequently used for initial orthodontic assessments and planning for dental implants.
The Pano is used for several key diagnostic purposes:
- Evaluating the position and development of all teeth, particularly assessing impacted or unerupted wisdom teeth and their location relative to nearby nerves for surgical planning.
- Detecting bone abnormalities within the jaw structure, such as cysts, tumors, or other growths developing far from the tooth roots.
- Offering a view of the nasal sinuses and other adjacent facial structures, allowing for the evaluation of potential sinus-related issues or infections.
Radiation and Safety Considerations
Modern panoramic units, especially those using digital sensors, operate with a significantly low dose of ionizing radiation. The radiation exposure from a single Pano is comparable to receiving only two to three days of the natural background radiation that people are exposed to every day in the environment. This minimal dose places the procedure on the very low end of medical imaging risks.
To ensure patient safety, standard protective measures are employed during the examination. Patients are typically given a lead apron to wear, which covers the chest and abdomen to shield the body from unnecessary exposure. Dentists follow the principle of using radiation “as low as reasonably achievable” (ALARA), only recommending a Pano when the diagnostic benefits outweigh the minimal exposure risk.