Marília Afonso Rabelo Buzalaf

In vitro assessment of an experimental coat applied over fluoride varnishes

Objective: The time of contact between the product and enamel surface is important in ensuring the efficacy of fluoride varnishes. Thus, some alternatives could avoid fluoride loss to saliva and improve the anticariogenic action of the product. This study evaluated the effect of an experimental coat on the anticariogenic action of fluoride varnishes. Material and Methods: Enamel bovine blocks were selected by evaluating surface microhardness and randomized into five groups (n=24): placebo, Duraphat™, Duraphat™ with coat, Duofluorid™ and Duofluorid™ with coat. Twelve blocks from each group were used to analyze calcium fluoride (CaF2) formed on enamel after treatment. The other 12 blocks were subjected to pH cycling for 7 days. The varnishes were kept on enamel for 6 h. Next, the percentage change of surface microhardness (%SMHC) and mineral loss (ΔZ) were calculated. CaF2 retained and fluoride present in the pH-cycled solutions were also measured. Results: The use of the coat did not decrease %SMHC and ΔZ, but all fluoride varnishes had better results when compared to the placebo (ANOVA and Kruskal-Wallis, respectively). The values from CaF2 formed were higher compared to the values of CaF2 retained (non-paired t test, p<0.05). There was a trend to decrease the amount of F in the solutions at the end of pH cycling (Kruskal-Wallis, p<0.05). Conclusions: Although the experimental coat increased the formation of CaF2 on the enamel surface, it did not significantly improve the anticariogenic action of fluoride varnishes.

In vitro evaluation of the abrasiveness of acidic dentifrices

AIM: This in vitro study evaluated the abrasiveness of acidic fluoride (F) dentifrices with different F concentrations on bovine enamel. METHODS: Enamel blocks (4.0x4.0 mm2, n=120) were selected according to their surface microhardness and divided into 12 groups. Slurries of dentifrices were used containing 0 (placebo), 275, 412, 550 and 1,100 ppm F (pH 4.5 or 7.0), as well as testing two commercial dentifrices (Crest™, positive control, 1,100 ppm F and Colgate Baby™, 500 ppm F). Enamel blocks were partially protected with an adhesive tape (control area) and then brushed by an automated toothbrushing machine (16,000 strokes). During this process, 0.4 ml of the slurries were injected every 2 mins on the enamel blocks. After toothbrushing, enamel wear was determined by profilometry. STATISTICS: Results were analyzed by ANOVA and Tukey’s test (p<0.05). RESULTS: The mean values for pH in the suspensions during treatment were 6.93, 4.32, 7.56 and 8.19 for neutral experimental dentifrices, acidic experimental dentifrices, Crest™ and Colgate Baby™, respectively. The abrasiveness of the acidic dentifrices was similar (p>0.05) to the neutral ones, whereas commercial dentifrices yielded lower abrasion (p<0.05). CONCLUSION: It was concluded that a reduction of the pH of dentifrices does not increase their abrasiveness.

New Preventive Approaches Part I: Functional Peptides and Other Therapies to Prevent Tooth Demineralization

The limited effect of fluoride on root caries has prompted the study of new preventive therapies, which involve recently developed functional peptides, lasers, phosphate-based technologies, among several other approaches. Most of the specific peptides currently investigated have been developed based on the available information related to the protective action of salivary proteins, including statherin-derived peptides. Other peptides include 8DSS, self-assembling peptide P11-4, antimicrobial peptides, and casein phosphopeptides combined with amorphous calcium phosphate. These were shown to increase remineralization and/or to protect against demineralization through different mechanisms, including the attraction of calcium ions to the demineralized tissue, delivery of available calcium, and antimicrobial action. Regarding phosphate-based technologies, the addition of polyphosphate salts to fluoridated vehicles has been shown to promote a synergistic effect in promoting enamel remineralization and in preventing demineralization, in studies with in vitro, in situ, and clinical protocols. Sodium trimetaphosphate has also been shown to promote intrafibrillar collagen remineralization, phosphate uptake by previously demineralized dentin, and deposition of needle-like crystallites at intrafibrillar level. As for the use of lasers, their effects on the mineral content and crystallinity of dentin were shown to be related to the removal of water and protein, besides surface melting by thermal degradation. Lasers have also been shown to have synergistic/additive effects with fluoride on the prevention of root dentin demineralization, due to the enhanced fluoride uptake and the decreased calcium and phosphate loss. Although the above-mentioned therapies seem to be promising alternatives to prevent root caries, clinical evidence is still required.