Formação de biofilmes derivados de saliva humana na superfície de diferentes resinas para placas estabilizadoras oclusais

Abstract

The aim of this study was to evaluate in vitro the influence of the surface characteristics of the resins used in the fabrication of occlusal stabilizing plates on the formation of polymicrobial biofilms derived from human saliva. 360 cylindrical specimens (4.0mm x 1.5mm) were fabricated with polymethylmethacrylate (PMMA) resins, divided into 3 groups according to the fabrication technique and resin used: RAT group (control) - conventional thermopolymerizable resin (n=120), RAF group - milled resin (n=120), and RAI group - printed resin (n=120). The surface free energy and roughness of the surfaces of each resin group were characterized. Biofilm formation was analyzed by adhesion tests, quantification of extracellular matrix, and surface characterization using scanning electron microscopy. Data related to resin surface characterization were subjected to analysis of variance (ANOVA) and Tukey's test, considering a significance level of 95% (α = 0.05). Mann-Whitney test was used for microbiological analysis. The RAI group presented the highest surface free energy (55.1º ± 5.82), indicating its higher hydrophilic characteristic compared to RAF (73.3º ± 4.71; p < 0.001) and RAT (71.7º ± 4.08; p < 0.001). There was no significant difference between the groups regarding surface roughness, although there was a higher tendency for roughness in the RAF group (16.1 ± 1.78; p = 0.067). Over a period of 4 days, the total biofilm formed was higher in the RAI group than in the RAT group (p < 0.05). There was no statistical difference between the RAF and RAT groups (p > 0.05). Greater biofilm formation was observed in the RAI group and lower formation in the RAF group throughout the analysis period (2, 4, and 6 days). On the 4th day, RAI showed the highest amount of carbohydrates in the matrix, which was statistically different from the control group (RAT; p < 0.05). On the 6th day, RAI and RAT showed no statistical differences (p > 0.05) in the total proteins present in the extracellular matrix of the formed biofilm. Extracellular matrix was not detected in the RAF group during this evaluated period. It is concluded that printed resin enabled greater biofilm formation from saliva, as well as the highest surface free energy. The best performance against biofilm formation from human saliva was observed for milled resin.