Influência de líquidos para modelagem nas propriedades físicas e análise da aderência de Streptococcus mutans em resinas compostas

Abstract

This study aimed to evaluate the effect of modeling liquids on hardness, contact angle, surface roughness, and biofilm formation in the resin composites. 80 disc-shaped specimens were made in the proportions of 8 mm x 1.5 mm, using two resin composites (Vittra APS and Filtek Z350 XT). As for the modeling liquids, the specimens were randomly divided into: absence of material for modeling (control group), Wetting Resin (Ultradent Products), Scotchbond Multipurpose (3M ESPE) and Single Bond Universal (3M ESPE). Knoop microhardness (n=10) was measured by a microdurometer with a load of 100 grams applied for 15 seconds. Hydrophobicity was determined by measuring the contact angle (n=3) with distilled water. The arithmetic mean roughness (Ra) (n=10) of the surface was measured using a rugosimeter. For bacterial adhesion (n=3), specimens were prepared, immersed in artificial saliva and incubated in culture media with bacterial suspensions of Streptococcus mutans at 37 °C in an atmosphere of 5% CO2 for 24 hours containing 5% sucrose. Colony-forming unit couting were determined with serial dilutions (x105 CFU/mL) and the biomass was determined by staining with crystal violet, through the absorbance read by a spectrophotometer. Quantitative values were tabulated and submitted to statistical analysis with α = 0.05. The control group had the highest Knoop hardness values for Vittra and Z350 XT, and the Single Bond Universal lower values for both resins. Vittra showed lower hardness values compared to Z350 XT, when subjected to Wetting resin and Scotchbond (p = 0.001). Scotchbond and Single Bond Universal had higher contact angles for Vittra (p = 0.003). The control obtained the lowest contact angle value for the Vittra. There was no statistical difference between the modeling materials for Z350 XT (p = 0.606), which in turn was inferior to Vittra when submitted to Scotchbond. Single Bond Universal and control had the lowest Ra values and Wetting resin the highest values for both resins (p = < 0.001). There was no significant difference for surface roughness (p = 0.967) and biofilm formation in the CFU/ml of S. mutans (p = 0.434) between the resins. The Z350 XT showed the greatest accumulation of total biomass (p = 0.034). Finally, although the adhesives showed a reduction in hardness, the use of them increased the contact angle properties and maintained the surface roughness and bacterial adhesion of the resin composites. Vittra and Z350 XT are similar for tested properties.