A submandibular fossa radiograph is an X-ray image that provides a view of a specific area located in the lower jaw. This diagnostic tool helps dental and medical professionals examine the region for various conditions.
Anatomy and Normal Appearance
The submandibular fossa is an anatomical depression found on the inner surface, or lingual aspect, of the mandible. This concavity naturally accommodates the submandibular salivary gland, one of the major salivary glands responsible for producing saliva.
On an X-ray, the submandibular fossa usually appears as a radiolucent area. This darker appearance is due to the presence of the softer salivary gland tissue and the thinner bone in this specific region. A clear superior border often defines this depression, helping differentiate it from other structures.
Common Reasons for Examination
Professionals often recommend a radiograph including the submandibular fossa when patients experience unexplained swelling or pain in the lower jaw area, specifically beneath the chin or along the inner side of the jawbone. Difficulty swallowing or a persistent dry mouth sensation can also prompt such an examination. These symptoms might indicate an underlying issue affecting the salivary glands or surrounding structures.
A history of previous salivary gland problems, such as recurring infections or palpable lumps in the submandibular region, also serves as a strong indication for imaging. Sometimes, a radiograph that includes this area is taken as part of a comprehensive dental examination when an anomaly is suspected during a clinical assessment.
Conditions Identified on Radiographs
Radiographs of the submandibular fossa can reveal several conditions affecting the submandibular gland or the surrounding bone. Sialolithiasis, which involves the formation of calcifications or stones within the submandibular gland or its main duct (Wharton’s duct), is a frequent finding. These stones appear as distinct radiopacities. Their presence can obstruct salivary flow, leading to swelling and pain.
Cysts and tumors can also manifest in this region, appearing as either radiolucent (darker) or mixed-density lesions depending on their composition. Salivary gland cysts, or even odontogenic cysts extending into the area from adjacent teeth, might present as well-defined dark areas. Benign or malignant tumors of the salivary gland or surrounding soft tissues can also be detected, sometimes showing irregular borders or areas of bone erosion.
The mandibular bone itself can be affected by various lesions in the submandibular fossa area. Conditions like osteomyelitis, an infection of the bone, or fibrous dysplasia, an abnormal bone growth, may show altered bone density or patterns. Occasionally, metastatic lesions from distant cancers can appear as irregular radiolucencies or radiopacities within the bone. Anatomical variations, such as a Stafne bone defect, which is a developmental concavity housing salivary gland tissue, can sometimes mimic a pathological lesion, though radiographs typically help differentiate this benign finding.
Types of Radiographs Used
Several types of radiographs can effectively visualize the submandibular fossa. The panoramic radiograph is a common general survey image that provides a broad view of both jaws, including the submandibular region. While useful for an overall assessment, its two-dimensional nature means structures can overlap, potentially obscuring smaller details.
An occlusal radiograph is a specific intraoral X-ray taken with the film or sensor placed in the patient’s mouth and bitten down upon. This view provides a clearer, more focused image of the floor of the mouth and the submandibular area, making it particularly valuable for detecting salivary stones in the submandibular duct. Periapical radiographs, primarily used for examining individual teeth and their surrounding bone, can incidentally show parts of the submandibular fossa if the image extends far enough posteriorly in the mandibular molar region.
For more complex cases or when detailed three-dimensional information is required, Cone Beam Computed Tomography (CBCT) is employed. This advanced imaging technique provides cross-sectional views, eliminating the superimposition inherent in traditional 2D X-rays. CBCT offers a comprehensive assessment of the submandibular fossa and its contents, allowing for precise localization of lesions and evaluation of their relationship to surrounding structures.