Effect of Acidulated Phosphate Fluoride Gel Application Time

A blind, crossover, in situ study by Dr. A. F. B. Calvo et al of the Piracicaba Dental School at the University of Campinas in Brazil, investigated the effect on caries reduction of application time (one minute versus 4 minutes) of acidulated phosphate fluoride gel (APF gel) in permanent and deciduous teeth. The 14-day study involved 16 adult volunteers who wore palatal appliances containing slabs of human permanent and deciduous enamel. At the beginning of each phase, the slabs were submitted to one of the following treatments: no APF application (negative control); APF gel (1.23% F) application for one or 4 minutes. Biofilm accumulation on the slab surface was allowed and the slabs were subjected 8 times a day to 20% sucrose to simulate a high cariogenic challenge. On day 15 of each phase, fluoride retained as calcium fluoride (CaF2) and fluorapatite (FAp) was determined on the enamel of the slabs and demineralization was assessed by cross-sectional microhardness. Fluoride as CaF2 and FAp, formed by APF gel application on the enamel slabs not subjected to the cariogenic challenge, was also determined. The study found that APF gel reduced demineralization in both enamel types, but the difference between one and 4 minutes was not statistically significant. CaF2 and FAp formed and retained on deciduous and permanent enamel was significantly higher in APF gel groups, but no significant difference was found between one and 4 minutes. The findings suggest that one minute of APF gel application provides a similar effect on inhibition of demineralization as 4 minutes for both permanent and deciduous enamel.
(Source: Caries Research. 2012, Volume 46, Number 1, pages 31 to 37; doi: 10.1159/000335125)