Fluorescence in dissolved fractions of human enamel

Fluorescence induced by laser light is useful in early detection of enamel caries. The present work studied the fluorescence emission pattern in dissolved human enamel and in different molecular weight fractions obtained after gel chromatography or dialysis followed by ultrafiltration. For comparison, solutions of synthetic hydroxyapatite and bovine enamel were used. When the entire emission and excitation spectra of the corresponding excitation and emission wavelengths in the solutions of human enamel and bovine enamel were compared, no distinct differences were found between the solutions. With excitation at 375 nm, emission peaks were found at 460 and 560 nm, indicating the presence in human enamel solution of two different chromophores, unevenly distributed over the molecular weight fractions. The 460-nm and the lower 560-nm fluorescence peaks seem to be derived from both organic and inorganic components. The inorganic substances contributing to both the 460-nm and 560-nm peaks were incorporated in complexes. The 560-nm emission peak elucidates part of the basis of the laser fluorescence method.