Use of zinc to increase fluorescence in an in vitro biofilm model as a tool for caries diagnosis

Abstract

Artificial sound enamel and caries enamel lesions were prepared. The sound enamel did not emit fluorescence in the visible spectrum. The spectrum of Zn(II)-protoporphyrin-9 biofilm from caries enamel lesions showed the fluorescence emitted by Zn(II)-protoporphyrin-9, with two main peaks at 630 and 690 nm. The luminescence properties of protoporphyrin-9 change depended on the amount of Zn(II). The increase in fluorescence intensity as Zn(II)-protoporphyrin-9 penetrated deeper to 1.75 mm was appropriate for the diagnosis of caries enamel lesions. Fluorescence intensity was maximum when Zn(II) reached 0.0256 µM and significantly produced a high contrast of fluorescence image together with high fluorescence quantum efficiency and photostability.