Computer simulations of structures and properties of the biomaterial hydroxyapatite

Carbonated hydroxyapatite is the major mineral phase in natural bone and teeth and is therefore an attractive material for use in tissue replacement applications. However, its successful application as a biomaterial requires a detailed understanding of its bulk and surface structures, defect chemistry, growth and dissolution behaviour and interaction with complex biomolecules. Computer modelling can aid experiment by investigating at the atomic level highly complex structures, properties and processes, which are still difficult or impossible to access with experimental techniques. Here, we describe our use of a combination of complementary computational techniques to investigate a number of topical issues relevant to the use of hydroxyapatite in biomaterials applications, including the bulk and surface structures of the pure material; the structure and location of carbonate impurities in the lattice; the uptake of fluoride and its effect on hydroxyapatite dissolution; and crystal growth inhibition by citric acid.