Ordering of self-assembled nanobiominerals in correlation to mechanical properties of hard tissues

Biominerals in the hard tissues of many organisms exhibit superior mechanical properties due to their unique hierarchical nanostructures. In this article, we show the microstructure of human tooth enamel examined by position-resolved small-angle x-ray scattering and electron microscopy. It is found that the degree of ordering of the biominerals varies strikingly within the dental sample. Combined with nanoindentation, our results show that both the hardness and the elastic modulus increase predominantly with the ordering of the biomineral crystallites. This can be attributed to the fact that the ordered structure helps sustain a more complex mechanical stress. (c) 2005 American Institute of Physics.