Fluoride uptake by proximal surfaces from professionally applied fluorides: an in vitro study

This study was performed to examine the uptake of fluoride by mesial enamel surfaces of extracted teeth from different types of topical fluoride. Forty-eight extracted human molars and twelve premolars were randomly divided into four groups and mounted in twelve wax blocks with five teeth in proximal contact in each block. Each group was treated for four minutes with either 1.23 percent acidulated phosphofluoride conventional gel, thixotropic gel, or foam in lined trays, or 2 percent neutral sodium fluoride solution applied with a cotton tip applicator. Acid-etch biopsies were performed three times to indicate the amount of fluoride uptake at three different depths. The results demonstrated that there was a statistically significant increase in fluoride uptake in the surface layer with both gels and foam (1150, 1058 and 1120 ppm F), whereas there was an insignificant increase with the fluoride solution (27 ppm F). In the deepest layer, the thixotropic fluoride produced the greatest fluoride uptake (919 ppm F) in comparison with the uptake from conventional gel (383 ppm F), foam (297 ppm F), or solution (118 ppm F).