Method: 80 caries-free mandibular third molars were embedded in the self-cured acrylic resin and buccal enamel surfaces were grounded with 1000 grid silicon-carbide papers. Enamel surfaces were coated with nail varnish leaving 8x6mm windows for exposure to demineralization/remineralization cycles. To compose artificial early enamel lesions, demineralization solution was prepared(pH: 4.8) and each tooth was kept in this solution for 72h at 37°C. After lesion formation, teeth were randomly divided in five groups(N=16):(1)Artificial saliva(negative control group)(pH:7.0), (2)Ozone (Ozonytron®X/Mymed,Munich,Germany), (3) NaF varnish(Colgate Duraphat Varnish/Colgate-Palmolive Company,New York,USA)(positive control group), (4)Resin infiltration system(Icon®/DMG,Hamburg,Germany), (5)CPP-ACP creme(Tooth Mousse/GC Corp.,Tokyo,Japan). Subsequently, all the specimens were subjected to pH cycling for 10 days to simulate the oral demineralization/remineralization conditions. The enamel surface microhardness and roughness measurements were determined at the baseline(T0), after demineralization(T1) and after pH-cycling(T2). The data were statistically analyzed with Kolmogorov-Smirnov test(p<0.05), Kruskal-Wallis(p<0.001), Friedman-test(p<0.001) and Two-Way ANOVA(p<0.05) using SPSS PASW statistics 15.0 software.
Result: No significant differences were observed among the groups at T0 and T1both for microhardness and surface roughness(p>0.05). The microhardness values at T2 were higher than T1 and lower than T0 in each group(p<0.001). T2 microhardness values revealed significant differences among the groups(p<0.001). CPP-ACP creme and resin infiltration applications increased the microhardness of artificial early enamel lesions significantly more than the arificial saliva, ozone and NaF varnish did(p<0.001). In respect to surface roughness, T2 values were lower than T1 and higher than T0(p<0.05) except resin infiltration group in which a slight increase was observed at T2(p>0.05). However, there were no significant differences at T2 surface roughness among the groups(p>0.05).
Conclusion: CCP-ACP creme and resin infiltration applications are more effective on the remineralization of early enamel lesions in comparison to NaF varnish and ozone applications.