HIGH-RESOLUTION ELECTRON-MICROSCOPIC OBSERVATIONS OF INITIAL ENAMEL CRYSTALS

Initial enamel crystals of porcine tooth germs were observed by means of high-resolution electron microscopy (HREM) and immunoelectron micro scopy. The observed spacings of lattice fringes were 0.82 nm, 1.04 nm, 1.39 nm and 1.65 nm. The lattice spacing of 0.82 nm represents the (1 00) plane of hydroxyapatite (KA). The other value were considered to r epresent modified octacalciumphosphate (OCP). In the initial process o f enamel crystal formation, OCP is a precursor of HA and grows on dent in crystals. OCP transform to HA, probably involving the hydrolysis of OCP and the epitaxial over-growth of HA on OCP.