Enamel solubility reduction by acidulated phosphate-fluoride (APF) treatment

The enamel solubility reducing (ESR) potential of acidulated phosphate-fluoride (APF) solutions containing varying amounts of F was studied. Commercial APF (1.23% F, pH 3.0) reduced solubility by about 80%. Fivefold dilutions of this APF were made with either phosphoric acid or water without significant effect on ESR potential. Further dilution to 0.12% F significantly decreased effectiveness. Commercially available APF products (1.23%) can be diluted several-fold with distilled water in the dental office without significant loss of ability to reduce the solubility of enamel.