Arthrography is most useful in diagnosing internal derangement of the TMJ because it allows for direct visualization of the articular disc position and mobility. This imaging technique can identify disc displacement, perforation, or adhesions within the joint, which are hallmarks of internal derangement. It provides dynamic assessment during mouth opening and closing, aiding in precise diagnosis and treatment planning. Arthrography is less effective in bony changes seen in osteoarthritis, ankylosis, or fractures, where other imaging modalities like CT or MRI are preferred.

Reference: Oral & Maxillofacial Pathology, Neville et al., 4th Edition.