Streptococcus pneumoniae prevalence in nasopharynx, oropharynx and gingival sulcus in Brazilian adults:A preliminary study.

AIM: This study aimed to evaluate the prevalence of S. pneumoniae colonization in three different sites in healthy adults: nasopharynx, oropharynx and gingival sulcus. METHODS: Two-hundred and sixty five adults, aged 20-60 years, who attended dental clinics in one public university (n = 106) and one military institution (n = 159) were enrolled in this study. Pneumococcal detection was performed by direct culture (DC) and PCR for lytA gene after a broth enrichment step. Capsular types were determined by sequential multiplex PCR. RESULTS: We identified 18 (6.8%) pneumococcal carriers among 265 adults by PCR, but only one (0.4%) pneumococcal strain was isolated by DC method. Oropharynx (17; 6.4%) was the main source of S. pneumoniae. Colonization of gingival sulcus and nasopharynx was found in 4 (1.5%) and 2 (0.8%) adults, respectively. Nine distinct capsular types were detected from 9 adults and co-colonization with 2 serotypes was confirmed in 4 (1.5%) subjects. Factors associated with carriage were being females, low level of schooling, non-military and regular medication. We observed a low (6.8%) pneumococcal carriage prevalence, but oropharyngeal samples yielded more sensitive results, especially by the PCR-based detection methodology. CONCLUSION: Gingival sulcus was found to be a possible reservoir for S. pneumoniae independently of the oropharynx or nasopharynx colonization.

Dentin biomodification potential depends on polyphenol source.

Although proanthocyanidins (PACs) modify dentin, the effectiveness of different PAC sources and the correlation with their specific chemical composition are still unknown. This study describes the chemical profiling of natural PAC-rich extracts from 7 plants using ultra high pressure/performance liquid chromatography (UHPLC) to determine the overall composition of these extracts and, in parallel, comprehensively evaluate their effect on dentin properties. The total polyphenol content of the extracts was determined (as gallic acid equivalents) using Folin-Ciocalteau assays. Dentin biomodification was assessed by the modulus of elasticity, mass change, and resistance to enzymatic biodegradation. Extracts with a high polyphenol and PAC content from Vitis vinifera, Theobroma cacao, Camellia sinensis, and Pinus massoniana induced a significant increase in modulus of elasticity and mass. The UHPLC analysis showed the presence of multiple types of polyphenols, ranging from simple phenolic acids to oligomeric PACs and highly condensed tannins. Protective effect against enzymatic degradation was observed for all experimental groups; however, statistically significant differences were observed between plant extracts. The findings provide clear evidence that the dentin bioactivities of PACs are source dependent, resulting from a combination of concentration and specific chemical constitution of the complex PAC mixtures.

Influence of the curing mode on fluoride ion release of self-adhesive resin luting cements in water or during pH-cycling regimen.

This study evaluated the effects of curing modes and storage conditions on fluoride release of resin cements. In phase 1, the cumulative fluoride release rate from samples of the resin cements (Panavia F 2.0, RelyX Unicem, MaxCem, and BisCem) was quantified after 15 days storage in water (n=4). In phase 2, the fluoride release profiles from the same materials were analyzed during pH cycling (n=4). In this second phase, fluoride was measured at specific times (one, two, three, five, eight, and 15 days). Disk-shaped specimens were prepared (10 mm × 0.5 mm), and the materials were either light activated or allowed to autopolymerize. For both phases, the fluoride release was measured using a fluoride ion-specific electrode. The fluoride release in water was not affected by the curing mode of RelyX Unicem and Maxcem resin cements. Panavia F. 2.0 and BisCem resin cements, either light cured or autopolymerized modes, released higher amounts of fluoride in water than the other self-adhesive cements. In phase 2, the concentration of fluoride released decreased from the first day of pH cycling until the 15th day for all resin cements, for both curing modes, regardless of the storage solution used (demineralizing/remineralizing). The fluoride release rate during pH cycling by Panavia F 2.0 and MaxCem was not affected by the curing mode. The effect of the curing mode on fluoride ion release in water or during pH cycling was product dependent.

Effect of curing mode on bond strength of self-adhesive resin luting cements to dentin.

In this study, the in vitro bond strength of dual-curing resin cements to indirect composite restorations when the cement was either light polymerized or allowed to only autopolymerize was evaluated. Occlusal dentin surfaces of 56 extracted human third molars were flattened to expose coronal dentin. Teeth were assigned to eight groups (n = 7) according to resin cement products and polymerization modes: conventional cement (Panavia F 2.0; Kuraray Medical) and self-adhesive cements [RelyX Unicem (3M ESPE), BisCem (Bisco), and G-Cem (GC Corp.)]. Cements were applied to prepolymerized resin discs (2-mm-thick Sinfony; 3M ESPE), which were subsequently bonded to the prepared dentin surfaces. The restored teeth were either light-polymerized through the overlying composite according to manufacturers' instructions or were allowed to only self-cure. After 24 h, the teeth and restorations were sectioned to obtain multiple bonded beams (1.0 mm(2)) and tested in tension at a crosshead speed of 0.5 mm/min until failure. Data (MPa) were analyzed by two-way ANOVA and Tukey test (alpha = 0.05). Light activation of some cement systems (G-Cem and Panavia F 2.0) increased the bond strength, while the curing mode did not affect the bond strength for some (RelyX Unicem and BisCem). The bond strength in the autopolymerized mode varied among products. In general, the use of self-adhesive resin cements did not provide significantly higher bond strengths than that of a conventional material, and two self-adhesive cements yielded significantly lower bond values (regardless of cure mode) than the other products.