This study evaluated the effect of some plaque and salivary factors on caries progression in situ. The salivary secretion rate, buffering capacity and mutans streptococci counts from 13 volunteers were determined. For three distinct periods of time, 4, 7 and 10 days, each of them wore a palatal appliance containing 4 bovine enamel blocks. They used a non-fluoridated dentifrice during the experiment and a 20% sucrose solution was dripped onto the blocks 10 times a day. Mutans streptococci (MS), calcium (Ca), and insoluble polysaccharide (IP) were quantified in the dental plaque formed on the enamel blocks, after each period. Enamel demineralization was assessed by surface microhardness, and the percentage of surface microhardness change (%SMC) in relation to the baseline values was calculated. Enamel demineralization occurred after each period of plaque accumulation (p < 0.05), and the %SMC increased with time (from 13.8 to 48.3%). The concentrations of Ca and IP in plaque were not statistically different among the experimental times, but significant correlations were found between these concentrations and %SMC. Neither the salivary factors assessed initially nor mutans streptococci in plaque presented statistically significant correlations to %SMC. The results suggest that enamel demineralization is time-dependent and is more related to the composition of the biofilm formed than to the salivary factors studied. DESCRIPTORS:Dental plaque; Tooth demineralization; Dental enamel; Streptococcus mutans; Saliva. RESUMO:Este estudo foi realizado para avaliar o efeito de alguns fatores salivares e da composição da placa dental na progressão da cárie in situ. O fluxo salivar, a capacidade tampão e os níveis de estreptococos mutans na saliva de 13 voluntários foram determinados inicialmente. Durante 3 períodos distintos de 4, 7 e 10 dias, eles utilizaram um dispositivo palatino contendo 4 blocos de esmalte bovino. Dez vezes ao dia, uma solução de sacarose a 20% foi gotejada sobre os blocos de esmalte. Durante o experimento, os voluntários utilizaram um dentifrício não fluoretado. Estreptococos mutans (EM), cálcio (Ca) e polissacarídeos insolúveis (PI) foram quantificados na placa formada sobre os blocos após cada período. A desmineralização do esmalte foi avaliada através de microdureza de superfície, e a porcentagem de perda de dureza de superfície (%PDS) foi calculada em relação aos valores de dureza iniciais. Houve desmineralização do esmalte após cada período de acúmulo de placa (p < 0,05) e a %PDS aumentou com o tempo (de 13,8 para 48,3%). As concentrações de Ca e PI na placa dental não foram diferentes entre os tempos experimentais, mas correlações significantes foram encontradas entre elas e a %PDS. Os fatores salivares avaliados inicialmente e os níveis de estreptococos mutans na placa não apresentaram correlação estatisticamente significante com a %PDS. Os resultados mostraram que a desmineralização do esmalte depende do tempo e está mais relacionada à composição do biofilme formado do que aos fatores sa...

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The results suggest that 10% PVP-I and 70% ethyl alcohol may be the most effective hand-cleansing agents for removing methicillin-resistant S aureus strain from either lightly or heavily contaminated hands.

The effectiveness of seven disinfectant compounds used in dentistry for a rapid decontamination of 32 guttapercha cones adhered with Staphylococcus aureus, Enterococcus faecalis, Escherichia coli strains or Bacillus subtilis spores was compared. Cones were treated with 2% glutaraldehyde, 1% sodium hypochlorite, 70% ethyl alcohol, 1% and 0.3% iodine alcohol, 2% chlorhexidine, 6% hydrogen peroxide, and 10% polyvinylpyrrolidone-iodine, for 1, 5, 10, and 15 minutes. After treatment, each cone was transferred to thioglycollate broth and incubated at 37ºC for 7 days. The products were bactericidal after 1 to 5 minutes and, with exception of ethyl alcohol and iodine-alcohol, sporicidal after 1 to 15 minutes of exposure. Results suggest that chlorhexidine, sodium hypochlorite, polyvinylpyrrolidone-iodine, hydrogen peroxide, and glutaraldehyde were the most effective products in the decontamination of gutta-percha cones.

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