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Effect of five different dental products on surface hardness of enamel exposed to chlorinated water in vitro.

The objective of this study was to assess the effect of five different dental products on surface microhardness of enamel exposed to chlorinated water in vitro. Sixty human sound premolar teeth, extracted for orthodontic reasons, were used and randomly divided into 6 groups (10 specimens each group: artificial saliva, 1,000 ppm fluoride toothpaste, CPP-ACP paste, CPP-ACP with 900 ppm fluoride paste, CPP toothpaste and tricalcium phosphate with 950 ppm fluoride paste. All specimens were immersed in chlorinated water at pH 5 for 24 hours and then remineralized by coating with a dental product from each group for 5 minutes and kept in artificial saliva at 37 degrees C for 6 hours. The surface microhardness of the enamel was measured with a Vickers hardness tester at baseline, after erosion by chlorinated water and after remineralization. Comparisons of the mean microhardness within each group were made a one-way repeated measures ANOVA and between groups using a one-way ANOVA and an LSD test at p < 0.05. The mean surface microhardness in all groups decreased significantly after eroding with chlorinated water and increased after remineralization. After remineralization, the mean surface microhardness of the artificial saliva group was significantly less than the other groups. Five different dental products (1,000 ppm fluoride toothpaste, CPP-ACP paste, CPP-ACP with 900 ppm fluoride paste, CPP toothpaste and tricalcium phosphate with 950 ppm fluoride paste) increased the hardness in vitro of eroded enamel caused by chlorinated water.