Differential diagnosis of calcium pyrophosphate dihydrate deposition of the temporomandibular joint

Calcium pyrophosphate dihydrate (CPPD) deposition disease (pseudogout) of t he temporomandibular joint (TMJ) is rare, It is characterized by the presen ce of crystal deposits that are birefringent under polarized light. Althoug h these crystals are characteristically weakly birefringent, some other cry stals such as those of calcium oxalate, synthetic steroids, and ethylenedia minetetraacetic acid are also birefringent, The differential diagnosis shou ld therefore be based on a quantitative analysis of crystals or observation of the crystal structure in calcified sections. We present a case of CPPD deposition disease of the TMJ and report on the value of such an analysis t o substantiate the diagnosis, (C) 2000 The British Association of Oral and Maxillofacial Surgeons.