The growth of calcium phosphates on natural enamel.

The kinetics of growth of calcium phosphate on seed materials prepared from human tooth enamel has been studied at 25 degrees C and pH 7.40 in stable supersaturated solutions of calcium phosphate. The grown material was characterized chemically, by specific surface area (SSA) measurements and by subsequent dissolution experiments. The marked increase in SSA in the early stages of the precipitation reaction parallel the results obtained with synthetic hydroxyapatite seed crystals and the results of the dissolution experiments indicate a chemical composition close to that of octacalcium phosphate for this intermediate phase. At low supersaturation it is possible to avoid the formation of the precursor phase.