Calcifications of the disc of the temporomandibular joint

Calcified lesions of the temporomandibular joint discs obtained from 135 hu man cadavers were studied. Calcifications were observed in 92 of 250 discs by soft x-ray radiography. Studies by light and electron microscopy and x-r ay diffraction revealed that there were two different types of calcificatio n in the discs: apatite crystal deposition with or without ossification, an d calcium pyrophosphate dehydrate (CPPD) crystal deposition. Calcifications were recognized more frequently posteriorly than anteriorly, and were rela ted to disc perforation. The results of this investigation suggest that dis c degeneration, which may occur as a result of aging or mechanical stress, causes calcifications.