Ultrastructural analysis of salivary calculus in combination with X-ray microanalysis.

Ultrastructural studies of salivary calculi were performed. Scanning electron microscopic examination of the calculi revealed lamellar and concentric structures. Granular or globular structures and pyramid structures were found on the surface of the calculi, and in some cases a scaly structure corresponding to fiber and bacteria was recognized. X-ray microanalysis showed the main constitutes of the calculi to be Ca and P. Transmission electron microscopic examination revealed a fine fibrous structure near the degenerated organelles, and analyses of the structure by electron diffraction revealed hydroxyapatite. Calcification was found around the degenerative organelles in the form of lipid-like structures, mitochondria, lysosomes, and microbial structures. Judging from our results, as one of the processes leading to calculi formation, it is speculated that degenerative substances are emitted by saliva, by some phenomenon, and calcification around these substances then occurs, contributing to the formation of calculi.