*Plain radiography : Plain films of TMJ are made with a stationaryx-ray source and film. In order to avoidsuperimposition of adjacent anatomic bonystructures making visualization of all parts ofTMJ, different projections of transcranial filmshave been applied, which include -lateral transcranial view - transmaxillary view - submental-vertex view - transpharyngeal view
*Panoramic radiographyIt’s a good imaging method for evaluating TMJsince information about the teeth and otherparts of the jaws were also shown on the image
However, the relationship between the condyleand glenoid fossa cannot be evaluated in thepanoramic film because the fossa cannot be seenwith superimposition of the base of the skull andzygomatic arch. The morphology of the condyle becomes widerthan the anatomic structure of the condyle
*TomographyTomography of TMJ is generated through thesynchronous movement of the x-ray tube andfilm cassette through an imaginary fulcrumlocated in the center of the desired imagingplane. Linear tomography and complextomography are involved
tomography is a good method for depicting theosseous changes with arthrosis in TMJFor evaluation of condyle position in glenoid fossaof TMJ, tomography has been reported to bemore reliable than plain film and panoramicradiographyOn the other hand, the relationship between thecondyle position and disc displacement isuncertain. The condyle position is not reliable inestimating the disc displacement of TMJ andrelated symptoms
The major disadvantage of tomography is the lackof visualization of the soft tissue of TMJ, aproblem shared with plain film radiography.
* Arthrography :A 25 or 23 gauge needle is placed into the inferiorjoint space immediately posterior to the condyle.Small amounts of iodinated contrast are injectedunder fluoroscopy. The contrast tracks along theposterior, superior and anterior portions of thecondyle. The anterior collection of contrast,called the anterior recess, normally has asmooth, tear-drop shape.
If the meniscus is perforated, contrast flows intoboth the superior and inferior joint recesses.However, the arthrographic needle caninadvertently puncture the meniscus and causeiatrogenic filling of both joint spaces.
*computed tomography (CT):Computed tomography (CT) can be used todiagnose internal derangement and otherdisorders of the TMJ.The patient is scanned in either the transverse ordirect sagittal plane using thin sections (1-2 mm)and a soft tissue technique.
If transverse sections are obtained, sagittalreconstructions are made through the condyle. The meniscus can be visualized on CT since it isslightly higher in density than the surroundingmuscle and soft tissue.
Normally, there is only a small amount ofincreased soft tissue density anterior to thecondyle on CT. In internal derangement, theanteriorly displaced meniscus results inabnormally increased soft tissue density anteriorto the condyle.
*Magnetic resonance imaging (MRI)Magnetic resonance (MR) can also be used todiagnose internal derangement and other disordersof the TMJ.The patient is scanned in the sagittal plane using asurface coil and a high resolution techniqueThe low intensity cortex of the condyle surrounds thehigh signal fat in the marrow. The meniscus is a lowintensity structure which is attached posteriorly bythe intermediate intensity bilaminar zone.
Normally, the anterior band lies immediately infront of the condyle. The junction of thebilaminar zone and the meniscus normally liesat the superior aspect of the condyle.
In internal derangement, the meniscus isabnormally positioned anterior to the condyle.