Orthopantomography, often referred to as an OPG or panoramic X-ray, is a specialized diagnostic imaging technique used in dentistry and maxillofacial surgery. This non-invasive procedure captures a wide, two-dimensional image of the entire mouth, providing a comprehensive view of the teeth, jawbones, and associated structures in a single film. The OPG offers dental professionals a broad overview of the patient’s anatomy, which is difficult to achieve with smaller, localized X-rays.
What is Orthopantomography
Orthopantomography is fundamentally different from traditional small dental X-rays, such as periapical or bitewing radiographs, because it is an extra-oral technique. Standard intraoral X-rays focus on one or two teeth, providing highly detailed images to detect small cavities or localized infections. The OPG sacrifices some fine detail to achieve a panoramic visualization of the entire curved dental arch, from ear to ear.
The technique uses tomography, where the X-ray source and the image receptor move simultaneously around the patient’s head. This coordinated movement creates a sharp image of structures within a specific layer, known as the focal trough, while blurring objects outside of this curved plane. The resulting image displays all the teeth in both the upper (maxilla) and lower (mandible) jaws, the Temporomandibular Joints (TMJ), and the surrounding bone structures, offering a comprehensive assessment. Dentists choose an OPG when they need this screening view to evaluate the overall health and structure of the maxillofacial region.
The Patient Experience
The procedure for an OPG is simple and fast, typically taking only a few seconds for the actual scan. Before the scan begins, patients must remove all metal objects from the head and neck area, including jewelry, hairpins, and removable dental appliances. These items can interfere with the X-ray beam and create blurring artifacts on the final image. The patient is positioned either standing or sitting in front of the orthopantomograph machine.
To ensure correct alignment within the focal trough, the patient is asked to bite down gently on a sterile mouthpiece and may have their chin resting on a small shelf. Head supports are used to keep the patient completely still during the brief exposure, which is crucial for obtaining a clear image. Once positioned, the machine’s rotating arm begins to revolve in a semi-circle around the patient’s head. The entire process is non-invasive and painless, requiring the patient only to remain stationary for the short duration of the rotation.
Diagnostic Applications
The wide scope of the OPG image makes it useful for identifying conditions affecting the entire jaw structure or multiple teeth simultaneously. It is frequently used to assess the status and position of developing or impacted teeth, such as wisdom teeth, which is important for surgical planning. Orthodontists rely on the OPG to evaluate the overall alignment of the teeth and the development of the jawbones before initiating treatment.
The radiograph provides a clear view of the mandible and maxilla, making it useful for detecting jaw fractures following trauma, or identifying cysts and tumors within the bone structure. The OPG also allows for the assessment of the Temporomandibular Joints (TMJ) for signs of disease or structural abnormalities. Furthermore, the image aids in pre-surgical planning for dental implants by evaluating the available bone height and quality.
Safety Profile and Considerations
A common concern with any X-ray is the exposure to ionizing radiation, but the OPG uses a very low dose, making it safe for routine diagnostic purposes. The effective radiation dose from a modern digital OPG is quite small, often estimated to be equivalent to only a few days of natural background radiation. This dose is significantly lower than that of a medical CT scan and is comparable to or less than a standard chest X-ray.
Dental professionals adhere to the ALARA principle—As Low As Reasonably Achievable—to minimize a patient’s exposure. They achieve this by using high-speed digital sensors, proper equipment settings, and providing a lead apron for additional shielding. While the radiation risk is minimal, patients who are or may be pregnant must inform their healthcare provider. The provider can then determine if the scan is immediately necessary or if it can be safely postponed.