The presence of extracellular polysaccharides matrix makes extraction and purification of RNA from Streptococcus mutans within biofilms challenging. In this study, several approaches to purify RNA extracted from S. mutans in suspension cultures and biofilms were examined. The combination of sonication (3 pulses of 30 s at 7 W), suspension in NAES buffer (50 mM sodium acetate buffer, 10 mM EDTA and 1% SDS; pH 5.0) and homogenization-mechanical cells disruption in NAES- acid phenol:chloroform, yielded 9.04 mg (or 0.52 mg) of crude preparation of RNA per 100 mg of total cell (or biofilm) dry-weight. The crude RNA preparations were subjected to various DNAse I treatments. The combination of DNAse I in silica-gel based column followed by recombinant DNase I in solution provided the best genomic DNA removal, resulting in 4.35 mg (or 0.06 mg) of purified RNA per 100 mg of total cell (or biofilm) dry-weight. The cDNAs generated from the purified RNA sample were efficiently amplified using gtfB S. mutans-specific primers. The results showed a method that yields high-quality RNA from both planktonic cells and biofilms of S. mutans in sufficient quantity and quality for real-time RT-PCR analyses.

The composition and biological activities of propolis, a resinous hive product collected by honeybees from various plant sources, depends on various factors such as season and vegetation of the area. The aim of this study was to evaluate the influence of the seasonal effect on the ethanolic extracts of Brazilian propolis (EEP) type 6 and type 12, collected during 6 months in terms of antibacterial activity and phenolic composition. The antimicrobial properties were evaluated by MIC and MBC on S. mutans Ingbritt 1600 and the profile of chemical composition by UV-visible spectrophotometry, HPLC-RF and GC-MS. The results demonstrated that the season in which propolis is collected influences its chemical composition, resulting in modifications in its antibacterial activity.

O objetivo deste estudo foi analisar in situ a efetividade de um dentifrício contendo monofluorfosfato (MFP) e sistema abrasivo fosfodicálcio diidratado (DCPD), quando comparado com dentifrício placebo. O estudo foi do tipo cross-over com oito voluntários em duas etapas de 45 dias. Os voluntários utilizaram dispositivo intra-oral palatino de resina acrílica contendo 4 blocos de esmalte com lesão de cárie artificial. Após cada etapa, foi analisada a incorporação de flúor (flúor total em ppm F) e microdureza (em Knoop) dos blocos de esmalte dental. Os resultados obtidos (média <FONT FACE="Symbol">±</font> E.P.) das áreas integradas sob as curvas demonstraram que a concentração de flúor incorporado no esmalte tratado com dentifrício MFP/DCPD foi significativamente maior que no placebo (4.508,55 <FONT FACE="Symbol">±</font> 965,82 e 1.485,51 <FONT FACE="Symbol">±</font> 191,72, respectivamente) e os dados de microdureza demonstraram que o dentifrício MFP/DCPD foi capaz de remineralizar o esmalte dental em 34%, enquanto no placebo observou-se perda de 14% de mineral. Assim, os dados obtidos deste estudo demonstraram que o dentifrício MFP/DCPD foi efetivo não apenas na incorporação de flúor no esmalte, mas também na capacidade de remineralizar a lesão de cárie, quando comparado com o placebo.

The aim of this study was to evaluate in situ the effectiveness of a dentifrice containing monofluorophosphate (MFP) and dicalcium phosphate dihydrate (DCPD). Eight volunteers took part in this crossover, double blind design study performed in two phases of 45 days. The subjects were acrylic resin appliances containing four blocks of human dental enamel with artificial caries to evaluate fluoride uptake and remineralization by MFP/DCPD and Placebo dentifrices. After each phase the blocks of enamel were removed and the analysis of total fluoride (ppm F) and microhardness (Knoop) were evaluated. The results of total integrated areas under the curves of the two dentifrices treatments showed that the MFP/DCPD dentifrice produced a significantly higher fluoride uptake than the Placebo dentifrice (4508.55 <FONT FACE="Symbol">±</font> 965.82 and 1485.51 <FONT FACE="Symbol">±</font> 191.72, respectively) and the microhardness data demonstrated 34% and -14% of remineralization for MFP/DCPD and Placebo dentifrices, respectively. It was concluded that MFP/DCPD dentifrice was effective not only on fluoride uptake, but also on remineralization of artificial caries lesions of human dental enamel.