Abstract
The dissolution behavior of calcium fluoride in saliva was investigated. Chemically pure calcium fluoride (200 mg) was equilibrated in 10 ml of either saliva or distilled water for 3 weeks or repeatedly exposed, at 15-min intervals, to 10 ml of fresh solutions of saliva, distilled water, or phosphate-or calcium-containing solutions. Calcium fluoride dissolved more readily in water than in saliva. The study confirmed that exposure to saliva caused formation of a dissolution-limiting layer and that this layer consists of surface-adsorbed phosphates and showed in addition that the dissolution rate was continuously reduced with time of exposure to saliva or phosphate buffer. Calcium fluoride-like material, formed on enamel by treatment with 2% NaF solution, was shown by scanning electron microscopy to have higher stability in saliva than in water after 3 weeks' incubation.