Energy absorption characterization of human enamel using nanoindentation

✍ Scribed by Li Hong He; Michael V. Swain

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 334 KB
• Volume: 81A
• Category: Article
• ISSN: 1549-3296
• DOI: 10.1002/jbm.a.31051

✦ Synopsis

Abstract

Enamel is a natural composite, which has much higher toughness than its major component, crystalline hydroxyapatite. In this study, the energy absorption behavior of human sound enamel was investigated with nanoindentation techniques. A UMIS nanoindenter system as well as a Berkovich and two spherical indenters with nominal tip radii of 5 and 20 μm were used to indent enamel at different loading forces in the direction parallel to enamel prisms. Inelastic energy dissipation versus depth of indenter penetration (U%–h~p~ curve) as well as a function of indentation strain (U%–ε curve) of enamel was determined. Enamel showed much higher energy absorption capacity than a ceramic material with equivalent modulus (fused silica). Even at the lowest forces (1 mN) for the 20 μm indenter, inelastic response was found. Additional tests done at different force loading rates illustrated that load rate has little influence on P–h response of enamel. The top surface of enamel has the plastic work of indentation of ∼5.2 nJ/μm^3^. The energy absorbing ability is influenced by the very small protein rich component that exists between the hydroxyapatite nanocrystals as well as within the sheath structure surrounding the enamel rods. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2007