Interaction of zinc with a synthetic calcium phosphate mineral.

As zinc has been included in several oral health products as an anticalculus and antiplaque agent, the interaction of zinc with a synthetic phosphate was investigated. The synthetic calcium phosphate used in this study was beta-tricalcium phosphate, or whitlockite, which is a major constituent of mature calculus. The aim of this work was to study the mechanism of uptake of zinc to this mineral. Zinc was readily taken up by the calcium phosphate to a maximum level of 13.9 mumol/m2. The interaction was reversible and followed a Langmuir adsorption isotherm. There was no concomitant release of calcium with zinc uptake. Inclusion of calcium in the exposure solution did however marginally depress the acquisition of zinc (12% max), but fluoride had no significant effect on uptake.