Varied Fluoride Concentrations for Topical Application to Modified Surface Enamel

Abstract

The aim of this study was to investigate the effect of varied F concentrations of APF solution on the F uptake of modified human surface enamel and the change of the acid resistance of the surface enamel, and also to find out the effective topical application procedure with the least fluoride concentration.
The sound enamel blocks were prepared from human premolars which were lightly processed by applying 0.05 M H₃PO₄ for 1 min., which has been used as a routine clinical procedure, called the mild etching, for the topical application of APF solution.
APF solutions of which the F concentrations varied from 0.05% to 1.2%, were applied for 4 min. to the enamel blocks and immersed into calcifying solution containing no fluoride for 30 min. The F uptake was determined by using the enamel biopsy technique and acid resistance was assessed by determining the dissolved amount of calcium when the enamel blocks were exposed to the acetic acid-sodium acetate buffer solution of pH 4.0.
The results obtained were as follows:
1. It was confirmed that after the mild etching, the surface enamel to which the APF solutions containing varied concentrations of F were applied, took up more fluoride than that without the mild etching. Obviously the mild etching did not alter the visual appearance of enamel surface leaving its original luster.
2. In the acid resistance test, APF applications with the mild etching enhanced acid resistance more than those without the mild etching. More than 0.5% F in the APF solution with the mild etching did not show any significant differences in the acid resistance of the surface enamel.