Comparison of the Rate of Demineralization using a QLF

Objectives: The objective of this study was to compare the rate of in vitro demineralization of bovine permanent (BP), human deciduous (HD) and human permanent (HP) enamel. Methods: Twenty five flattened and polished enamel samples for each group (BP, HD, HP) were immersed in a demineralizing solution (0.1 mol/L lactic acid, 0.2% Carbopol 907, and 50% saturated hydroxyapatite) for 1, 2, 4 or 8 days. All 25 samples from each group were subjected to Quantitative light-induced fluorescence analysis (QLF) and 5 samples from each group were randomly selected for Transverse Microradiography analysis (TMR). Integrated mineral loss (IML) and lesion depth (LD) were determined by TMR. The fluorescence radiance (FR) of sound enamel (FR_S), demineralized enamel (FR_D) were determined by QLF and FR ratio (FR_D/FR_S) was calculated. Results: All enamel samples showed significant correlation between FR ratio and demineralization time in serial QLF analysis (p<0.05). The constant of regression analysis were as follows: BP enamel was -3.085 (p<0.05), HD enamel was -1.021 (p<0.05) and HP enamel was -1.820 (p<0.05) in serial QLF analysis. IML and LD values increased as a function of demineralization time in all samples. The FR ratio decreased with demineralization time in all samples. The significant correlations were found for the BP enamel samples between TMR values and demineralization time (IML=0.762^**, LD=0.730^**) and for the HP enamel samples between TMR values and demineralization time (IMD=0.883^**, LD=0.869^**) and between FT ratio and demineralization time (r=-0.520^*). Conclusion: From the results of this in vitro study show that the rate of demineralization of human deciduous enamel was approximately one-third the rate of demineralization of bovine enamel and approximately half of the rate of demineralization of human permanent enamel.