Panoramic tomography of the maxillofacial region
Last reviewed: 23.04.2024
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On the panoramic tomogram (orthopantomogram), which is a kind of zonogram, the entire dentogram system is displayed. The image is increased by 30%.
During the shot, the tube and the cassette with the film and the reinforcing shields describe an eccentric incomplete circle (about 270 ') around the patient's fixed head. In this case, the cassette also rotates about the vertical axis. All this ensures the passage of X-rays perpendicularly (orthoradially) to each portion of the jaw and cassette.
Only a certain layer is visible in the image: a thicker section (2-2.7 cm) in the lateral regions of the premolar and molar regions, and less thin (0.4-0.8 cm) - in the central part, the image of which is less clear . In order to avoid projection of the cervical vertebrae on the frontal region, the patient's neck should be straightened and even slightly bent forward. The picture shows all the lower jaw, alveolar bay and the relationship of the roots of the teeth with the bottom of the maxillary sinus, the elements of the pterygoid fossa (the posterior wall of the maxillary sinus and the pterygoids of the main bone). The posterior parts of the sinus are outside the excreted layer.
The informativeness of the method makes it possible to recommend it for trauma and inflammatory diseases, cysts, neoplasms, systemic jaw lesions, in persons with multiple caries, periodontal diseases, with prosthetics and orthodontic treatment.
The installation of an orthopantomograph requires an area of 20 m 2. The device can be installed in the procedural general diagnostic cabinet with its area of 55 m 2.
In panoramic X-ray photography, the anode of a sharp-focus tube (focal spot diameter 0.1-0.2 mm) is inserted into the oral cavity, and the X-ray film in a polyethylene cassette with amplifying screens is placed from the outside. On direct panoramic radiographs, the image of the upper or lower jaw and dentition is obtained, on the lateral - the right or left half of both jaws.
The technique is most informative in examining the frontal sections of the upper and lower jaws. The images of the upper jaw show the relationship between the roots of the teeth and pathological processes with the bottom of the nasal cavity and maxillary sinus. Due to the high radiation load, this technique is rarely used at present.
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