Verification of behaviour of human enamel for fracture toughness determination

Abstract

Enamel is the hardest biological tissue in the human body because of its structure and composition. The structure of interlocking rods enables this biomaterial to resist the stresses of mastication. Unfortunately, enamel is prone to fracture initiation and growth. Determining the fracture toughness of enamel is a difficult task. The lack of thickness makes it impossible to prepare samples which could be analysed by usual methods. Other authors ordinarily use Vickers indentation fracture test (VIF) to determine the fracture toughness of enamel. The VIF is, however, not generally acceptable. The aim of this study is a verification of a fracture behaviour of enamel using nanoindentation. In the study the impact of changes of hardness (HIT) and reduced modulus (Er) caused by crack initiation and the growth on fracture toughness determination is observed. The next goal is an evaluation of loading rate impact.