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Traditional diagnostic techniques detect root caries when it is relatively advanced and significant tissue has been lost. The purpose of this study was to determine the ability of the quantitative light-induced fluorescence system (QLF) for detecting and quantifying incipient demineralization in dentin. Thirty-two clinically sound tooth surfaces were ground and polished to remove the enamel and 1-mm of the outer layer of dentin. Polished surfaces were cleaned with 0.1 M EDTA (pH 7.8) for 4 min to remove the smear layer. Specimens were painted with a transparent acid resistant varnish leaving a 2E2-mm window exposed. Specimens (8/group) were coded and distributed randomly in four groups: 40 h, 120 h, 240 h, and control. Groups 40 h, 120 h, and 240 h were demineralized at 37°C for different time periods: 40 h, 120 h, and 240 h, respectively. The control group was kept in humid conditions at 4°C. After incubation, varnish was removed and QLF images were taken. Specimens were then sectioned, stained with rhodamine B (0.1 mM) and analyzed by confocal microscopy for lesion depth. QLF average change in fluorescence detected significant differences between the 240-hour group and all the other groups (pd0.001). Differences between the 120-hour group and the 40-hour and control groups were not significant (p = 0.02), but showed a clear trend. Results of the confocal analysis of the 40 h, 120 h, and 240 h showed an average lesion depth of 74, 152, and 233 Ìm, respectively; all groups were significantly different (pd0.05). No lesions were found in the control group. Pearson's correlation coefficient between the QLF average change in fluorescence and the lesion depth was r = 0.64 (pd0.00014). Results of this study suggest that the QLF system has the potential to detect and quantify small carious lesions in dentin. |