Evaluation of biofilm formation on acrylic resin surfaces coated with silicon dioxide: an in situ study

Abstract Biofilm on acrylic resin dental prostheses may cause gingival inflammation. This study evaluated the influence of a silicon dioxide coating layer applied onto acrylic resin on the adhesion of microorganisms. Blocks (5 x 5 x 3 mm) of acrylic resin were evaluated for surface roughness and divided into two groups: control (CG) and coated with silicon dioxide (LG group). The specimens were evaluated by scanning electron microscopy (n = 1) and by contact angle analysis (n = 3). For the in situ study, 20 volunteers wore acrylic palatal devices containing three samples from each group (n = 60) for 2 days. The biofilm formed was quantified by metabolic activity and total biomass using the crystal violet assay. The results were subjected to Bartlett's normality test and Gamma model with random effect for the response variable (α = 5%). The mean contact angle of the coated group was significantly lower than that of the uncoated group (p < 0.05). The metabolic activity of microorganisms in the biofilm on the blocks treated with coating was significantly lower than that of control blocks (p = 0.02). Regarding the amount of extracellular matrix produced by the microorganisms, there was no difference between the CG and LG group (p = 0.05). The application of a silicon dioxide coating on acrylic resin reduced the activity of the polymicrobial biofilm formed in situ. This coating may be advantageous for patients with conventional complete dentures or implants made of acrylic resin and who have motor difficulties that prevent them from cleaning their prostheses properly.

Fatores de virulência de Candida spp isoladas de cateteres venosos e mãos de servidores hospitalares / Virulence factors for Candida spp recovered from intravascular catheters and hospital workers hands

Avaliou-se o potencial de virulência de 23 leveduras isoladas de cateteres e mãos de trabalhadores em um hospital do Noroeste do Paraná. As leveduras isoladas de cateter foram mais aderentes e hidrofóbicas (P<0,05) que as leveduras isoladas das mãos. Candida não-albicans expressaram com mais intensidade os fatores de virulência avaliados.

The virulence potential of 23 yeasts recovered from intravascular catheters and the hands of workers in a hospital in the northwestern region of Paraná were evaluated. Yeasts recovered from catheters presented greater adherence and were more hydrophobic (p<0.05) than yeasts recovered from hands. Candida non-albicans species expressed the virulence factors evaluated more intensely.

Produção de biofilme por leveduras isoladas de cavidade bucal de usuários de prótese dentária / Biofilm production by yeasts isolated from bucal cavity of prosthesis wearers

Foi analisada a presença de espécies do gênero Candida na saliva de indivíduos distribuídos em três grupos: 1) com prótese e lesão; 2) com prótese sem lesão; 3) sem prótese e sem lesão, correlacionando com a capacidade de produção de biofilme em meio Sabouraud dextrose, contendo 8 por cento de glicose, sendo determinada por leitura em espectrofotômetro. Dos 220 pacientes foram isoladas 92 leveduras: 24 (grupo 1), 24 (grupo 2) e 44 (grupo 3). Em 70 por cento foi isolado C. albicans e 30 por cento C. não albicans. A produção de biofilme em maior freqüência (64 por cento) foi encontrada entre as leveduras C. não albicans e a maior porcentagem na produção de biofilme, quanto aos grupos de pacientes, foram 75, 63 e 57 por cento correspondendo aos grupos 1, 2 e 3, respectivamente. Esses dados sugerem que a produção de biofilme das espécies do gênero Candida pode estar associada ao processo infeccioso destes isolados