Remineralization Potential of Tea Extracts on Incipient Dentin Lesions

Abstract

It has been reported that tea leaves have anticariogenic properties that can be attributed to the inherent catechin and predominant fluoride present within tea leaves. Our earlier research demonstrated that enamel and dentin lesions treated with PF-4 (partially refined green tea extract; fluoride concentration 3,900μg/g) containing an acidic buffer exhibited significantly low mineral loss. The aim of this study was to evaluate the remineralization enhancement potential of PF-4 on incipient dentin lesions in vitro. Samples were cut from bovine root dentin and a 1×3mm flat experimental window was made on each sample. The baseline subsurface lesion was made by immersing samples in a methylcellulose gel and acetic acid buffer demineralization system (1.5mmol/l CaCl₂, 0.9mmol/l KH₂PO₄, 25mmol/l acetic acid, 0.4ppm F, pH5.0). Remineralization buffers (1.5mmol/l CaCl₂, 0.9mmol/l KH₂PO₄, 130mmol/l KCl, 20mmol/l Hepes, pH7.0) containing 0, 0.025, 0.05 and 0.1 weight percent of PF-4, and 1.0ppm F as NaF were prepared. Samples were immersed in one of these remineralization buffers for 14 days at 37℃. The mineral profile, integrated mineral loss (IML) and lesion depth (LD) were analyzed by transversal microradiography. Remineralization was observed in all groups, and "hyper-remineralization" was detected in the PF-4 containing groups. The IML of the PF-4 containing groups was significantly lower than the baseline, 0%, and NaF groups. Furthermore, the IML of the PF-4 groups decreased with PF-4 concentration in a dose dependent relationship. The IML and LD of the 0.025% group were significantly lower than the NaF group, which contained the same amount of fluoride. This difference can be accounted for by the organic substrates present in PF-4. Our results suggest that PF-4 has superior remineralization potential caused by the contained fluoride and macromolecules together with calcium and phosphate in saliva.