X-ray View for TMJ
Panoramic radiography (OPG) has no diagnostic utility for TMJ disorders and should not be used 1, 2. Instead, the choice of imaging depends entirely on whether you suspect soft tissue or bone pathology.
Imaging Selection Algorithm
For Suspected Soft Tissue Pathology (Disc Displacement, Ligament/Capsule Issues)
- Contrast-enhanced MRI is the gold standard for evaluating TMJ ligament-capsule tissue disorders, disc position and morphology, and detecting active inflammation 1, 2.
- MRI is the only modality that adequately visualizes the articular disc and soft tissue components 2, 3.
- Clinical examination alone misses TMJ inflammation in up to 42% of cases, making imaging essential when clinical suspicion exists 1, 2.
For Suspected Bone Pathology (Condylar Fracture, Degenerative Changes, Bone Lesions)
- CBCT or CT scan is the gold standard when medical history and clinical examination suggest condyle or glenoid cavity involvement 1, 2.
- CT is superior to radiography for evaluating mandibular condyle fractures, particularly posterior and minimally displaced fractures 4.
- CT with multiplanar reformations is nearly 100% sensitive for detecting mandibular fractures and identifies comminution and displacement critical for surgical planning 4.
What NOT to Use
Panoramic Radiography (OPG)
- Panoramic radiography is insufficient for TMJ assessment and does not supply adequate information about joint components, disc, or ligament-capsule structures 1, 2.
- While OPG has 86-92% sensitivity for simple mandibular fractures, it misses condylar and subcondylar fractures with anterior displacement, and nondisplaced/minimally displaced anterior fractures 4.
- OPG can better visualize dental root fractures compared to CT, but this is irrelevant for TMJ pathology 4.
Conventional Radiography
- Transcranial views, conventional tomography, and other plain films are inadequate for TMJ evaluation 2, 5.
- These techniques have been replaced by cross-sectional imaging modalities 3.
Common Pitfalls to Avoid
- Using CBCT solely to obtain lateral and panoramic projections exposes patients to unnecessary radiation when the same information can be obtained with lower-dose techniques 2.
- Ordering imaging without clear clinical indication wastes resources; imaging should only be performed when it contributes to proper diagnosis and treatment with better prognosis 6.
- Relying on clinical examination alone will miss significant pathology, particularly active inflammation 1, 2.
- Interpretation of MRI has subjectivity influenced by technique, equipment, and reader expertise; small amounts of TMJ fluid or minor contrast enhancement may represent normal variation 2.
Practical Approach
Start with clinical assessment to determine suspected pathology type:
- If suspecting disc displacement, clicking, locking, or inflammatory arthritis → order contrast-enhanced MRI 1, 2.
- If suspecting trauma, degenerative bone changes, or structural bone abnormalities → order CBCT or CT 1, 2.
- If diagnostic uncertainty exists after initial imaging → consider the alternative modality to evaluate the other tissue type 1.