Rz. Legeros et al., Zinc effect on the in vitro formation of calcium phosphates: Relevance to clinical inhibition of calculus formation, AM J DENT, 12(2), 1999, pp. 65-71
Purpose: To determine the effect of zinc on the in vitro formation of calci
um phosphates and its relevance to calculus inhibition. Materials and Metho
ds: Different types of calcium phosphate phases (amorphous calcium phosphat
e, ACP; dicalcium phosphate dihydrate, DCPD; octacalcium phosphate, OCP; an
d carbonate hydoxyapatite, CHA) were precipitated from solutions containing
increasing concentrations of zinc (Zn) ions. The precipitates were charact
erized using x-ray diffraction, infrared absorption spectroscopy, and scann
ing electron microscopy. Results: The presence of Zn ions affected the type
and amount of calcium phosphate phases formed. Zn, even at concentrations
as law as 0.1 mM/L, inhibited the crystal growth of DCPD, OCP and AP; and,
at higher concentrations (0.5 mM to 2 mM/L), promoted the formation of amor
phous calcium phosphate, ACP, or Zn-substituted tricalcium phosphate (beta-
TCP) depending on the reaction pH and temperature.