A review of near infrared spectroscopic features of teeth, bone and artificial hydroxyapatite

Hydroxyapatite is a major component of teeth and bones and is used commercially in metal sequestration. Near infrared imaging and spectroscopy has found increasing use in characterisation of these materials, particularly in context of dental conditions. The near infrared spectra of these materials are reviewed in terms of band assignments related to water in various states, P-OH and organic material, and in terms of light scattering. The effect of factors such as acid and heat on the NIR spectra of bones and teeth is also described. This review is intended to provide a resource for future researchers using NIR spectroscopy in characterisation of hydroxyapatite containing material.