What Is Stafne Bone Defect (SBD)?
Stafne bone defects are rare defects that affect the lower jaw, mainly the posterior segment. Stafne bone defect usually occurs at the mandibular lingual cortex located in the posterior portion of the mandible. Occasionally, there may be cases with cavities in the anterior portion of the mandible, but these are rare. The anterior cavities occur in the canine-premolar region of the mandible. Edward C. Stafne described SBD in 1942 and reported at least 35 cases of Stafne defect. The lesion also has a rare anterior variation that Richard and Ziskind described in 1957.
What Are Some Other Terms for Stafne Bone Defect?
The following terms have also been used to refer to Stafne bone defect:
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Stafne bone cavity.
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Stafne idiopathic bone cavity.
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Lingual mandibular bone defect.
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Lingual mandibular salivary gland depression.
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Lingual mandibular cortical defect.
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Static bone cyst.
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Latent bone cyst.
Who Is Commonly Affected by Stafne Bone Defect?
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Stafne bone defect usually occurs in men who are between 50 years and 70 years of age.
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The prevalence of SBD has been estimated at 0.1 to 0.48 %.
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Some studies have shown that it can also occur in individuals as young as 11 to 30 years of age.
What Causes Stafne Bone Defects?
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The cause of the Stafne bone defect is not fully known or perceived.
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However, it has been suggested one mechanism by which the defect occurs is through the proliferation or translocation of adjacent salivary glands or soft tissues. This results in the remodeling of the lingual cortical plate.
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Entrapment of salivary gland tissue within the bone is another possible causative factor for the Stafne defect.
What Are the Signs and Symptoms of Stafne Bone Defect?
Stafne bone defect is usually asymptomatic. A clinical examination does not typically yield any definitive medical signs either. SBD usually presents as a unilateral defect and hardly ever appears bilaterally. A few cases may present with lingual mucosal depression on the mandible.
Other rare symptoms include:
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Pain.
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Bleeding.
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Ulceration.
How Is Stafne Defect Diagnosed?
Stafne defect is accidentally diagnosed radiographically during other, unrelated dental treatments.
The following are the diagnostic techniques that may be used for SBD:
1. Panoramic Radiograph:
They appear as well-circumscribed, monolocular, round, or ovoid radiolucent lesions near the angle of the mandible when observed on a panoramic radiograph. They are located between the inferior alveolar nerve and the lower mandibular margin or the inferior border of the posterior mandible (between the molar teeth and the angle of the jaw). The size of these defects ranges from 1 cm to 3 cm. The border appears well-corticated, so the defect does not affect adjacent or surrounding structures.
2. Computed Tomography (CT) Scan:
The lesion appears as a shallow defect when viewed through the medial cortex of the mandible. It possesses an easily distinguishable corticated rim. While a part of the submandibular gland may be affected, soft tissue abnormalities do not typically arise due to the lesion and are therefore not visible on the CT scan. Three-dimensional CT reconstruction can help define and understand the spatial relationship between the bone defect and the inferior alveolar nerve.
3. Sialography:
Sialography may also aid in the diagnostic process as it can demonstrate the presence of salivary gland tissue within the bone.
4. Tissue Biopsy:
A tissue biopsy does not help with the diagnosis since the histopathologic features on a biopsy indicate normal salivary gland tissue. An empty cavity may be noticed in some cases if the gland has been displaced. Some biopsies may also show the presence of blood vessels, connective tissue, lymphoid tissue, and fat. There is a better likelihood of proper diagnosis through a biopsy when the lesions are in the anterior region of the mandible. They appear as radiolucent defects that may superimpose the lower anterior teeth or disrupt the contour of the lower mandibular border.
5. Magnetic Resonance Imaging (MRI) Scan:
MRI scans are better options than conventional CTs for the following two reasons:
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First, they do not cause ionizing radiation.
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They display the contents within the lesions quite clearly.
However, MRI scans also have some associated concerns, including the following:
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They may cause discomfort to the patient.
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They are not cost-effective.
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Image distortion may occur, and radiographic artifacts may be present.
MRI helps describe the submandibular gland prolongation into the stafne defect in the mandible. Therefore, it is used as an alternative in cases where CT is not recommended.
6. Other Diagnostic Particulars:
The defect does not increase in size or change in radiographic appearance, which means that it stays static. This can help when attempting to diagnose the lesion, as this characteristic static feature may set it apart from other lesions that are similar in appearance but not necessarily unchanging.
The anterior variant of SBD generally appears as a radiolucent, ovoid, or ellipsoid concave lesion. It is located in the canine-premolar mandibular area and is similar to the posterior variant's clinical and radiographic appearance.
How Is Stafne Defect Treated?
The treatment of the Stafne defect is unnecessary since it is not considered a pathological condition. It causes no ill effects, abnormalities, or pathological changes. However, there is a possibility of the occasional abnormality arising due to the lesion. In addition, the presence of salivary gland tissue means that salivary gland tumors may be seen within the defect. This is a rare occurrence but not impossible.
In rare cases, if the stafne defect cause discomfort or pain, then surgical treatment may be considered. During surgery, the surgeon may surgically excise the entire jaw. Symptomatic relief can be provided by pain management and anti-inflammatory medications.
What Factors Should Be Considered in the Differential Diagnosis of Stafne Bone Cyst?
Clinical examination and imaging techniques may help recognize and rule out neoplasms such as lymph node malignancy and salivary gland tumors.
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Anterior SBDs may be misdiagnosed as residual cysts. Differential diagnosis relies on the fact that SBD has no association with teeth, whereas residual cysts typically occur during the extraction of a tooth with severe apical infection.
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Differential diagnosis of odontogenic and non-odontogenic cysts is also required. The best way to differentially diagnose SBD from cysts, such as ameloblastomas, dentigerous cysts, and radicular cysts is to establish the presence or absence of an association with a relevant tooth. SBD does not have any such association, while most cysts are associated with teeth (inflamed, infected, or unerupted).
Conclusion:
Individuals affected with SBD hardly ever find out that they have the condition unless it has been diagnosed during a routine dental examination. Therefore, there is no cause for concern, and the defect does not hamper life or affect the quality of one’s oral health. Patients do not need to worry or seek treatment for a case of SBD, as it is not required. Associated side effects are rare and mostly absent.
