Mechanism of Incorporation of Fluoride into Bone Salt

¹ Department of Physiological Chemistry, Wayne State University College of Medicine, Detroit, Michigan

Bone salt, in the form of either finely powdered teeth or freshly formed precipitate, was equilibrated with serum salt solutions and then allowed to exchange with radio-calcium or radiophosphate until a state of equilibrium was reached. When dissolved fluoride was added to these equilibrating solutions, most of the fluoride was removed from solution, and the amounts and specific radioactivity of dissolved calcium and phosphorus were decreased. The decrease in specific activity was due to solution of unexchanged bone salt. When fluoride was added to the equilibrating solutions in concentrations less than 3 ppm, the amounts of calcium and phosphorus dissolved plus their decreased levels in solution were about equal to the amounts required for the precipitation of the fluoride as fluorapatite. Precipitation of fluoride as fluorapatite on bone-salt surfaces appears to be an important mechanism for the removal of small amounts of fluoride from dilute salt solutions.