HARDNESS AND YOUNGS MODULUS OF HUMAN PERITUBULAR AND INTERTUBULAR DENTIN

A specially modified atomic-force microscope was used to measure the h ardness of fully hydrated peritubular and intertubular dentine at two locations within unerupted human third molars: within 1 mm of the dent ine-enamel junction and within 1 mm of the pulp. The hardness of fully hydrated peritubular dentine was independent of location, and ranged from 2.23 to 2.54 GPa. The hardness of fully hydrated intertubular den tine did depend upon location, and was significantly greater near the dentine-enamel junction (values ranged from 0.49 to 0.52 GPa) than nea r the pulp (0.12-0.18 GPa). A Nanoindenter was used to estimate the Yo ung's modulus of dehydrated peritubular and intertubular dentine from the unloading portion of the load displacement curve. The modulus valu es averaged 29.8 GPa for the peritubular dentine (considered to be a l ower limit), and ranged from 17.7 to 21.1 GPa for the intertubular den tine, with the lower values obtained for dentine near the pulp.