NANOINDENTATION TESTING OF HUMAN ENAMEL AND DENTIN

Abstract

The objective of this investigation is to characterize the indentation behaviour of human enamel and dentin using instrumented indentation methods. The experiment was realized in different conditions; at indentation loads from 5 mN to 400 mN, loading rates from 10 to 1000 mN/min and constant loads from 10 to 400 mN for 1000 s. The indentation hardness (HIT), reduced modulus (EIT), and influence of applied load and loading rate on hardness and the creep behaviour have been evaluated. The hardness of enamel is the highest at its occlusal surface, decreases towards the dentin-enamel junction (DEJ) and has the lowest value at DEJ. The maximum value of HIT was 6.53 ± 1.12 GPa in enamel and 1.08 ± 0.11 GPa in dentin. The average reduced modulus EIT was 92.86 ± 3.86 GPa and 22.95 ± 0.08 GPa in enamel and dentin, respectively. A significant load-size effect has been found during testing the hardness of enamel. The indentation load rate had only a minor influence on the penetration depth/energy loss of enamel. The creep deformation of enamel at 10 and 400 mN and 1000 s is 70 nm and 160 nm, respectively, with stress exponent n = 1.8.

Keywords

• Human enamel
• Dentin
• Nanoindentation
• AFM
• Microstructure