ABSTRACT
Infrared (IR) spectroscopy is a vibrational spectroscopy technique for chemical composition or structure determination that was first applied to the identification of calcium phosphate mineral phases in bones and teeth. In terms of biominerals, IR spectroscopy has been applied to characterize calcium phosphates and carbonate substitution in enamel, the bacterial layer coating teeth, and pathologic calcium phosphate deposits. The paradigm shifts in IR spectroscopy came with the coupling of a light microscope with an IR spectrometer early in the 1980s and the addition of a focal plane array detector later in the 1980s, but commercial units were not readily available until 10 years later. IR spectroscopy can be applied to solutions and gases as well as solids, but IR microspectroscopy and IR microspectroscopic imaging are generally applied to tissue sections. IR images can be used to illustrate the lipid distribution in healthy and diseased bone.
