Cross-sectional hardness of enamel from human teeth at different posteruptive ages.

This study evaluated, by cross-sectional hardness (CSH), enamel maturation at different depths in sound human teeth at different posteruptive ages (12 per age group): unerupted (molars; control), 2-3 years (premolars), 4-10 years (premolars) and >10 years (molars). Cross-sectional Knoop hardness was measured at 10, 30, 50, 70, 90, 110, 220 and 330 mm depth from the surface. The data were subjected to two-way ANOVA followed by Bonferroni's pairwise tests (a = 0.05). The CSH significantly increased with posteruptive age, indicating that the time of exposure in the oral cavity might result in deep enamel maturation.