Abstract
The present study was undertaken to gain information about the chemical composition and crystallographic feature of calcified tissues found in various fibro-osseous lesions, namely, ossifying fibroma/osteoma, osteosarcoma, and fibrous dysplasia. For references, we also examined dystrophic calcifications found in calcifying epithelial odontogenic tumor and necrotic lymphnodes, as well as cortical bones of human jaws at varying ages. The calcified materials were collected from 18 patients after surgical operation and then fixed in neutral formalin. Parts of the tissues were processed for histological examination, while the rest were freezedried and then pulverized for analyses. The results showed that all calcified specimens comprised microcrystals of carbonatoapatites , exceptionally accompanying the precipitation of calcium carbonate in one case of osteoma and whitlockite in two cases of necrotic lymphnodes. The crystallinity of apatite crystals in the pathogenic fibro-osseous tissues exhibited an improvement with tissue maturation, approaching the level of crystallinity of the age-matched bone crystals. In contrast, apatite crystals in the dystrophic calcifications exhibited higher crystallinity than those of the cortical bone and the fibro-osseous tissues. The conformity between the normal and pathogenic bony tissues supports the view that pathogenic calcification in the fibro-osseous lesions is a type of "biologically controlled mineralization" and that the common regulatory mechanism operates to induce carbonation of bioapatites even under pathologic environments.
