Caries detection by diode laser Raman spectroscopy

Carious lesions can be distinguished from sound hard tooth tissues because their near-infrared Raman spectra exhibit an increased luminescence. A comparison of the ratio between luminescence and Raman band intensities for diseased and healthy areas of the tooth gives a measure for the stage of the disease. Intraoral analyses can be made in a reasonable time with the use of a diode laser, a fiberoptic Raman probe, and a compact spectrograph without moving optics. An excitation wavelength of 785 nm gives sufficient contrast between sound and carious tissue and allows a sensitive detection of the weak Raman scattering by silicon detectors.