Sophisticated imaging techniques of the temporomandibular joints, such as CBCT and MRI, are not indicated for every TMD patient. The decision to acquire specialized imaging should be based on a careful history and examination, and then obtained only when there is reason to believe that imaging will improve the diagnosis and/or guide the appropriate treatment. If the clinical presentation is suggestive of an internal derangement, a fairly reliable diagnosis can usually be made from a thorough history and examination, without specialized imaging. A good quality panoramic image of the oral region is recommended as a routine screening image to rule in or out a variety of conditions. This should be taken with the mandible protruded maximally so that the TMJ condyles are clearly seen.
Specialized imaging of the temporomandibular joints can provide information regarding both hard and soft tissues, as well as the relationships of the joint structures. However, no single technique can provide all of the information that might be required. Therefore, before ordering an imaging study, it is essential to know what kind of information is needed to enhance the diagnostic process. The table above, Imaging of the TMJs, is provided as a guide to selecting appropriate imaging studies. A careful history and examination should form the basis for recommending any imaging beyond a screening study.
Diagnosis of some conditions that affect the TMJ cannot be made by means of history and clinical examination alone and more sophisticated imaging, beyond a screen panoramic, may be indicated. These may include congenital and developmental malformations of the mandible and/or cranial bones, and acquired disorders, including neoplasia, fractures, dislocations, ankylosis, and disc displacement, as well as inflammatory diseases and a wide range of arthritides.
As previously stated, the selection of appropriate imaging of the temporomandibular joints should be based on a thorough history and examination. Imaging should not be considered the primary basis for diagnosis but, when indicated, should supplement the clinical evaluation. Selection of imaging should be based on what technique will provide the desired information at the lowest cost and least radiation.
For example, when hard tissue imaging of the TM joints is indicated, tomography will be less costly and will expose the patient to less radiation than will conventional CT. However, with the advent of Cone Beam CT (CBCT), radiation exposure is considerably less than conventional CT and particularly with the potential to view the selected structures from any angle, this option has become a reasonable choice for imaging hard tissue. Unfortunately, CBCT cannot provide imaging of the articular disc or other intracapsular soft tissue.
• Developmental Disorders
• Disc Derangements
• TMJ Dislocation (Subluxation)
• Inflammatory Disorders