Efeitos de agentes umectantes sobre a rugosidade, alteração de cor, formação e impacto de biofilme em resina micro-híbrida sob desafio microbiológico e exposição ao café

Abstract

Biofilm formation and extrinsic staining compromise the longevity of composite resin restorations. This in vitro study evaluated the effects of two wetting agents, modeling resin (M) and universal adhesive (A), on the surface properties of a microhybrid resin under microbiological challenge and coffee exposure. Circular specimens were divided into six experimental groups (n=12): Control (C), Modeling (M), and Adhesive (A), with (P+) and without (P−) polishing. The samples were subjected to a dual-species biofilm (S. mutans and C. albicans) for 3 or 7 days and, subsequently, to a 7-day immersion in coffee. Biofilm formation (CFU), roughness (Ra), Knoop hardness, and color change (ΔE00) were evaluated. In the microbiological analysis, statistically significant differences between groups were observed only for Candida albicans, with the greatest increase in fungal load found in the Polished Control group (CP+). Regarding roughness, only the Unpolished Adhesive group (AP−) showed a statistically significant increase throughout the experiment. Surface hardness decreased significantly in the control groups after the challenges, whereas the groups with wetting agents showed greater stability. All groups exhibited a clinically perceptible color change after coffee immersion, with no significant differences among them. It was concluded that the type of wetting agent had a minimal impact on the resin properties. The most determining factor was the surface finish, where polishing proved essential for maintaining hardness and roughness but was not effective in controlling fungal colonization, reinforcing the need for additional strategies for microbial control in composite resin restorations.