Laser Induced Fluorescence of Carious Lesion Porphyrins

Objectives: This paper reports the preliminary results of the measurements of laser induced fluorescence in several porphyrin solutions. Coproporphyrin and uroporphyrin are common constituents of carious lesions. Their property to exhibit fluorescence when irradiated with a light of certain wavelength could be used as a means to detect carious lesions. Materials and methods: Absorption coefficient measurements of coproporphyrin I dihydrochloride and uroporphyrin I dihydrochloride solutions were performed under different pH conditions in order to identify spectral regions for effective laser excitation. Lasers with discrete wavelengths at 420 nm, 473 nm and 532 nm were used for the induction of the fluorescence. Results: At all laser wavelengths interesting fluorescence bands peaking at 591 nm, 619 nm and 652 nm for coproporphyrin and at 617 nm and 680 nm for uroporphyrin were observed. Conclusions: When combined together all bands should correspond to the spectral band structures found in real carious lesions.