Indiana University-Purdue University Indianapolis (IUPUI) / Two of the three fluoride varnishes sold on the American market today are sold in 10-ml tubes of 5.0-percent NaF varnish (Duraphat and Duraflor). Pilot studies have shown that a separation of contents within these tubes exists. The purpose of the current study was four-fold: 1) to measure the fluoride concentration gradient in 10-ml tubes of fluoride varnish, based on the resting position of the tube prior to use; 2 ) to compare a varnish 's concentration gradient to its ability to inhibit caries in an artificial caries environment; 3) to compare and contrast fluoride concentration gradients of Duraphat and Duraflor; and finally, 4) to determine if Quantitative Light Fluorescence(QLF) can detect differences in lesions developed when exposed to an artificial caries environment and fluoride varnish. Human teeth specimens were subjected to a caries challenge and treated with a sample of fluoride varnish from one of five categories: Duraphat stored horizontally and vertically for one week; Duraflor stored horizontally and vertically for one week; or a CavityShield 0.4 ml unit-dose. Results show that no significant fluoride/ppm differences exist between groups (p = 0.29). It was shown that the order in which Duraflor varnish was dispensed from the tubes significantly affected the fluoride concentration (p < 0.05). The order effect was not significant for Duraphat (p = 0.99). QLF data analysis shows there is no significant difference (p > 0.05) in the amount of remineralization obtained by using any varnish stored in any position. This was confirmed using confocal microscopy. These results indicate that all three brands of fluoride varnish are able to remineralize incipient in vitro carious lesions, regardless of from which part of the 10-ml tube the varnish is taken. However, a fluoride concentration gradient exists in tubes of Duraflor. Also, QLF is able to detect denmineralized and remineralized incipient lesions.