engleski

Laser induced fluorescence of common porphyrins in carious lesions

Objectives: Changes in optical properties of light reflected from carious tooth seem to be most interesting for early caries diagnostics. Previous studies have identified fluorescing compounds of caries, uroporphyrin (UP) and coproporphyrin (CP). The aim of this study was to carry out spectroscopic studies of CP and UP absorption spectra and laser induced fluorescence. Methods: Stock solutions of the uroporphyrin I dihydrochloride (UP) and coproporphyrin I dihydrochloride (CP) were prepared by dissolving 3.6 mg of CP and 1.0 mg of UP in 10 mM NaOH followed by neutralization with 100 mM HCl and dilution with distilled water. The concentration of the resulting stock solutions were 5.0x10-4 M and 1.1x10-4 M for CP and UP, respectively. Absorption coefficient measurements of CP and UP solutions under different pH conditions were performed on a Varian spectrophotometer (model CARY 3) in order to identify spectral regions for effective laser excitation. We used discrete laser wavelengths at 420 nm (15mW), 472.6 nm (20 mW) and 532 nm (5mW) for the laser induced fluorescence of UP and CP detected by the digital spectrometer (HR4000CG-UV-NIR, OceanOptics). Results: We observed fluorescence bands peaking at 591 nm, 619 nm and 652 nm for coproporphyrin and at 617 nm and 680 nm for uroporphyrin. Conclusion: When combined together all bands should give structure which could be found in real carious lesions. This study was supported by MZOS projects 035-0352851-2857, 065-0352851-0410 and 119-1191342-2959.

caries ; porphyrins ; laser ; fluorescence

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