Estudo in vitro da formação do biofilme de Candida albicans em resina acrílica termopolimerizável revestida por nanopartículas de dióxido de silício (revestimento cerâmico)

Abstract

This study investigates an experimental coating (VIPI LTDA, Pirassununga, SP) by sol-gel process that modifies acrylic resin denture base with silicon dioxide nanoparticles (SNP) to decrease C. albicans biofilm growth. Therefore, it was first investigated the presence of sol-gel ceramic coating on polymethylmethacrylate (PMMA) by Fourier Transform Infrared Spectroscopy (FTIR). Then C. albicans biofilms were quantified by colony forming units (CFU/mL) and confocal scanning laser microscopy (CSLM). Fifty-one PMMA specimens were manufactured (10x10x3mm) and assigned to the experiments. To evaluate specimens' composition, it was analyzed three groups (n=1): CN-the specimen did not receive any surface treatment; CP-it was applied the coating primer on the specimen surface CL-the specimen was treated with the whole sol-gel process. In the following stage, 48 samples were divided into 3 groups (n=16) according to the polish type: PM3-3µm of roughness mechanical polish; PM03-0,3µm of roughness mechanical polish;PL-liquid polish. Samples of experimental group were coated according to manufacturer's instructions and all the samples were sterilized with ethylene oxide.After that, they were dipped in artificial saliva for 2hs to acquire the salivary pellicle, and then, dried and inoculated with 2 mL suspension of C.albicans (1.10 7 cel/mL) for 90 min. Then, specimens were washed and immersed in sterile RPMI solution (37⁰C for 12h). Half of the samples of each group (n=8) was assigned to each quantification test (UFC/mL and CSLM). By CSLM and software (BioImageL v.2) analysis was possible to obtain the total biovolume (µm and then by one way ANOVA followed by Tukey's test to assess difference between groups (p<0,05). FTIR results showed an adequate SNP deposition, allowing the quantification tests to be performed. UFC/mL and CLSM records showed similarity between PL and PM3 groups and difference when comparing these groups to smoother surfaces group (PM03). Therefore, in this study, the experimental coating was not effective to reduce colonization by C. albicans biofilm on PMMA surfaces.Nevertheless, further investigations are required since sol-gel ceramic coating process eases the features modification of the material, possibly leading to an ideal coating development.