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The purpose of this study was to determine the efficacy of a fluoride varnish (FV), a 2% NaF gel, and a 1.23% APF gel in inhibiting progression of incipient secondary caries (SC). Human molars were used, on which a 1x4x1.5 mm cavity was prepared and restored with composite resin. SC lesions were developed using a microbial caries model (4 days). Half of each specimen was then painted with an acid-resistant nail varnish to maintain the baseline lesion. Specimens were divided into 4 groups, and were either not treated (control), treated with FV (removed after 24 h), NaF gel (applied for 4 min), or APF gel (applied for 4 min) prior to being subjected to 4 more days of bacterial challenge. At the end of the study, specimens were analyzed using Quantitative Light-Induced Fluorescence (QLF), sectioned through both the baseline and treated lesion sides, stained with Rhodamine B, and analyzed using confocal laser scanning microscopy (CLSM) to determine the extent of the change in the lesion after treatment. CLSM data indicated significantly smaller (p < 0.05) wall lesion depth changes for the FV group compared to the APF gel group. QLF .Q indicated significantly smaller changes for the FV group than the NaF gel and untreated groups. All other comparisons were not significantly different; however, there was a pattern for FV having the greatest impact on lesion progression for all data measured, and the APF treatment was generally more effective than NaF. The results suggest that the application of a fluoride varnish to an active SC lesion significantly retards lesion progression. Suipported by the National Institute of Health (USA) grant #P01 DE13540. |