The Relationship Between a Remineralization in the Subsurface Lesion of Bovine Enamel and a pH of Acid Phosphate Fluoride Solution

Abstract

The aim of this study was to quantify, in vitro, the formation of calcium fluoride after the application of six acid phosphate fluoride solutions (APF solution) with various pH (2.0,2.5,3.0,3.5,4.0,5.0) and to evaluate a remineralization of the subsurface lesion of bovine enamel treated with those APF solutions using the quantitative light fluorescence method (QLF). The Quantity of alkali-soluble fluoride (CaF₂) on the enamel surface increased through raising the acidity of APF solution and the largest one was an APF solution with pH 2.5. A uniform surface coating consisting of the small globules (less than 0.1μm in diameter) of calcium fluoride overlying the bovine enamel was observed after treatment with APF solution of pH 2.5. The surface morphology however changed becoming coarse and a quantity of fluoride decreased with the lowering of the acidity of the APF solution. A dispersion of fluoride into the subsurface lesion of the enamel increased through raising the acidity of the APF solution. After treatment with APF solution with pH 2.5 a large amount of fluoride dispersed into a depth of 30-40μm from the enamel surface. The highest recovery of the mineral of the surface layer occurred in APF solution with pH 2.5 followed by APF solution with pH 3.5; the least recovery was in the control (without APF solution).