CPP-ACP Promotes SnF2 Efficacy in a Polymicrobial Caries Model.

Dental caries is associated with plaque dysbiosis, leading to an increase in the proportions of acidogenic and aciduric bacteria at the expense of alkali-generating commensal species. Stannous fluoride (SnF2) slows the progression of caries by remineralization of early lesions but has also been suggested to inhibit glycolysis of aciduric bacteria. Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) promotes fluoride remineralization by acting as a salivary biomimetic that releases bioavailable calcium and phosphate ions, and the peptide complex has also been suggested to modify plaque composition. We developed a polymicrobial biofilm model of caries using 6 bacterial species representative of supragingival plaque that were cultured on sound human enamel and pulsed with sucrose 4 times a day to produce a high cariogenic challenge. We used this model to explore the mechanisms of action of SnF2 and CPP-ACP. Bacterial species in the biofilms were enumerated with 16S rRNA gene sequence analyses, and mineral loss and lesion formation were determined in the enamel directly under the polymicrobial biofilms via transverse microradiography. The model tested the twice-daily addition of SnF2, CPP-ACP, or both. SnF2 treatment reduced demineralization by 50% and had a slight effect on the composition of the polymicrobial biofilm. CPP-ACP treatment caused a similar inhibition of enamel demineralization (50%), a decrease in Actinomyces naeslundii and Lactobacillus casei abundance, and an increase in Streptococcus sanguinis and Fusobacterium nucleatum abundance in the polymicrobial biofilm. A combination of SnF2 and CPP-ACP resulted in a greater suppression of the acidogenic and aciduric bacteria and a significant 72% inhibition of enamel demineralization.

Effect of traditional and alternative intracoronal bleaching agents on microhardness of human dentine.

The purpose of this study was to compare the effect of traditional and alternative bleaching agents on microhardness of human dentine when used intracoronally. Thirty-six premolars were divided into six groups and bleaching agents were sealed into the pulp chambers as follows: group 1--distilled water (control), group 2--30% hydrogen peroxide solution, group 3--sodium perborate mixed with distilled water, group 4--sodium perborate mixed with 30% hydrogen peroxide solution, group 5--35% carbamide peroxide gel, group 6--35% hydrogen peroxide gel. Access cavities were sealed and the teeth were stored in distilled water at 37 degrees C. After 7 days, each tooth was sectioned at the cemento-enamel junction level and microhardness testing was carried out on dentine. The results showed that treatment with 35% hydrogen peroxide gel, 30% hydrogen peroxide solution and 35% carbamide peroxide gel reduced the microhardness of outer dentine to a small extent while treatment with sodium perborate mixed with water and sodium perborate mixed with 30% hydrogen peroxide solution did not significantly alter the microhardness of dentine.