Human teeth with and without caries studied by laser scattering, fluorescence, and absorption spectroscopy

The visible elastic light scattering and fluorescence emission from carious and noncarious regions of teeth were measured and compared. Carious teeth regions scattered light less effectively than noncarious regions for the spectral region 480-600 nm. The spectral shape of the fluorescence excited by a coherent source was similar to emission produced by incoherent (lamp) excitation. For both modes of excitation the emission peaks at approximately 550 nm. Differences in the fluorescence and light scattering spectra from carious and noncarious regions at a given wavelength was found not to be constant across the spectrum. Laser-induced fluorescence spectra for gamma irradiated teeth (total dose of 2000 rad) showed differences from control samples; the emission was blue shifted relative to the unirradiated samples. In addition, the relative visible absorption spectra for a tooth was measured in the visible region.