Influence of pH and oxygen-inhibited layer on fluoride release properties of fluoride sealant

Abstract 

Objectives

This study tested the hypothesis that the oxygen-inhibited layer on a light-cured methacrylate based resin and the pH of the storage medium would increase significantly the initial fluoride release and long-term release rate from fluoride dental sealant.

Methods

Forty-eight discs (16-mm diameter×1-mm thick) were made from FluroShield (<5wt% NaF) and Helioseal F (<30wt% fluorosilicate glass) sealants. For each sealant, 24 discs were cured through a Mylar^® strip that covered the surface and the remaining 24 discs were cured in air allowing formation of the oxygen-inhibited surface. Each specimen in the 24-disc groups was stored individually in 25-mL vials, and divided into four six-vial groups to receive 10mL of pH4–pH7 (designation of pH 4–7) lactate buffer solutions. The buffer solutions were replaced periodically up to 121 days. The cumulative fluoride release over time was used to determine the coefficients for short-term and long-term release.

Results

Two-way ANOVA showed that the mean coefficient values for either sealant were significantly influenced by the curing condition (p<0.0001) and pH (p<0.0001), except for short-term release from NaF sealant. The duration of short-term release was much longer for the fluorosilicate glass sealant.

Conclusions

Both pH and the source of fluoride source incorporated in the sealant play significant roles in fluoride release.

Keywords: pH, Oxygen-inhibition, Sealant, Fluoride release, NaF, Fluorosilicate glass