Journal of Dental Research, Vol 55, 617-624, Copyright © 1976 by International & American Associations for Dental Research Online Journals
Seeded growth of calcium phosphates: effect of different calcium phosphate seed material
G. H. Nancollas and J. S. Wefel
Seed crystals of OCP, TCP, and HAP are effective nucleators of DCPD in
stable supersaturated solutions under conditions in which DCPD is the
predominant phase. The crystals will grow with the second-order kinetics
(TCa = 5.0 X 10(-3)M, Tp = 1.0 X 10(-2)M [pH, 5.60]) characteristic of
DCPD. TCP is the least efficient, DCPD growth taking place only after an
initial induction period. In all instances, the rate of DCPD
crystallization is proportional to the square of the supersaturation with
respect to DCPD, and the reaction is surface controlled. Scanning electron
micrographs show an amorphous or microcrystalline precursor to the
development of the characteristic platelets of DCPD. In stable
supersaturated calcium phosphate solutions at a physiologic pH (TCa = 1.4 X
10(-3)M, Tp = 8.0 X 10(-4)M [pH, 7.40]), only OCP and HAP seed crystals are
effective nucleators. The efficiency of OCP as a nucleator adds further
evidence for its participation as a precursor in the precipitation of HAP
under these conditions.
