The formation and mineralization of dentin

Abstract
Observations were conducted at the light and electron microscope level of the formation and mineralization of dentin. At the light level it was shown that predentin is made up of the odontoblast process, collagen fibers and a ground substance. As mineralization occurs, the fibers tend to condense and thicken in areas adjacent to the odontoblast process. Fibers continue to invade the developing matrix and, as in early dentinogenesis, they appear at all times to be derived from the pulp.At the E.M. level the significant observations made in reference to dentin formation consist of the identification of granular masses appearing in the interfibrillar spaces initially in the region of the dentino enamel junction. Histochemical tests at the E.M. level demonstrated that the odontoblasts elaborate an acid mucopolysaccharide which concentrates in granules at the base of the odontoblast process. Subsequently these granules are extruded into the matrix where the polysaccharide becomes concentrated in the interfibrillar spaces and to come extent on the collagen fibers. The onset of mineralization occurs in the patches of mucopolysaccharide, later also on the fibers. It appears that the presence of an acid mucopolysaccharide is a prerequisit for mineralization in the dental matrix.