Monofluorophosphate Blocks Internal Polysaccharide Synthesis in Streptococcus mutans.

Streptococcus mutans is the leading cause of dental caries worldwide by accumulating a glycogen-like internal polysaccharide (IPS) that contributes to cariogenicity when sugars are in excess. Sodium monofluorophosphate (MFP) is an active anticariogenic compound in toothpastes. Herein, we show that MFP inhibits (with an I0.5 of 1.5 mM) the S. mutans ADP-glucose pyrophosphorylase (EC 2.7.7.27), which catalyzes the key step in IPS biosynthesis. Enzyme inhibition by MFP is similar to orthophosphate (Pi), except that the effect caused by MFP is not reverted by fructose-1,6-bisP, as occurs with Pi. Inhibition was correlated with a decrease in acidogenesis and IPS accumulation in S. mutans cells cultured with 2 mM sodium MFP. These effects were not mimicked by sodium fluoride. Considering that glycogen synthesis occurs by different pathways in mammals and bacteria, ADP-glucose pyrophosphorylase could be visualized as a molecular target for controlling S. mutans virulence. Our results strongly suggest that MFP is a suitable compound to affect such a target, inducing an anticariogenic effect primarily by inhibiting a key step in IPS synthesis.

Remineralization potential of an anticaries/antigingivitis mouthrinse.

PURPOSE: To assess the ability of a new formulation (Listerine with 0.022% NaF) to remineralize initially decalcified bovine enamel compared to a positive control, clinically established 0.022% NaF rinse. METHODS: A cyclic demineralization/remineralization in vitro model was utilized and the level of remineralization was monitored by examining the Knoop microhardness over 6 and 18 D/T/R cycles RESULTS: (1) both the test formulation and positive control rinses were statistically significantly effective in remineralizing artificial lesions in vitro; and (2) the test formulation performed "at least as good as" the positive control. These results support the concept that the remineralization potential of the fluoride rinse is not adversely affected by the addition of essential oils.

Ab initio study of AmCl(+): f-f spectroscopy and chemical binding.

A valence full configuration interaction study with a polarized double-zeta quality basis set has been carried out for the lowest 49 electronic states of AmCl(+). The calculations use a pseudopotential treatment for the core electrons and incorporate a one-electron spin-orbit interaction operator. Electrons in the valence s, p, d, and f subshells were included in the active space. The resulting electronic potential energy curves are largely repulsive. The chemical bonding is ionic in character with negligible participation of 5f electrons. The molecular f-f spectroscopy of AmCl(+) arises essentially from an in situ Am(2+) core with states slightly redshifted by the presence of chloride ion. Am(+)+Cl asymptotes which give rise to the few attractive potential energy curves can be predicted by analysis of the f-f spectroscopy of isolated Am(+) and Am(2+). The attractive curves have substantial binding energies, on the order of 75-80 kcal/mol, and are noticeably lower than recent indirect measurements on the isovalent EuCl(+). An independent empirical correlation supports the predicted reduction in AmCl(+) binding energy. The energies of the repulsive curves are strongly dependent on the selection of the underlying atomic orbitals while the energies of the attractive curves do not display this sensitivity. The calculations were carried out using our recently developed parallel spin-orbit configuration interaction software.

Effect of fluoride/essential oils-containing mouthrinse on the microhardness of demineralized bovine enamel.

PURPOSE: To assess the ability of a fluoride mouthrinse containing a fixed combination of essential oils (thymol, menthol, eucalyptol, and methyl salicylate) to inhibit demineralization as compared with that of a clinically established NaF rinse. METHODS: Inhibition in sound bovine enamel to demineralization was assessed utilizing a cyclic T/R/D (treatment/remineralization/demineralization) in vitro model where Knoop microhardness was monitored over 6, 12, and 18 T/R/D cycles. RESULTS: Both fluoride-containing mouthrinses resulted in statistically significant increase in microhardness when compared to the non-fluoride control mouthrinse, possibly demonstrating and validating the in vitro model's ability to parallel the clinically established benefit of a 0.022% NaF rinse to inhibit demineralization. In addition, the test formulation was shown to be "at least as good as" the NaF positive control in increasing enamel microhardness following each of the 6, 12, and 18 T/R/D cycles.