Efeito da adição de nanopartículas de óxido de zinco e cobre em um sistema adesivo universal nas propriedades adesivas e antimicrobianas: estudo in situ

Abstract

Objective: This study aimed to evaluate the effect of copper and zinc oxide nanoparticles (Cu/ZnONp) added into a universal adhesive system (Ambar Universal APS, FGM) on the antimicrobial and dentin bonding properties when submitted to a cariogenic challenge in-situ. Methods and materials: The experimental adhesive, (0.2/5% Cu/ZnONp), and the control (0% Cu/ZnONp) were applied to enamel-free fifty-six third molars distributed into four groups (n=14) based on the adhesive strategy (etch and rinse [ER] and self-etch [SE]). Teeth were

restored with composite resin, and longitudinally sectioned into resin-dentin beam- like specimens which were randomly allocated to an immediate evaluation (IM,

24hrs) and to a cariogenic challenge (CC). For CC, specimens were placed in an intra-oral palatal device used by 14 volunteers for two phases of 21 days each with a washout period of 7 days, after the first 21 days and followed by biofilm harvest and specimen removal. Antimicrobial properties were assessed against several microorganisms with colony forming units per milligram (CFU,log/mg), biofilm characterization by SEM imaging, Knoop microhardness (KHN), and mineral loss (ML). Bonding properties were evaluated through microtensile bond strength (μTBS) and nanoleakage (NL) for IM and after CC; degree of conversion (DC) was assessed only for IM. For KHN, μTBS and NL it was used a three-way ANOVA and a two-way ANOVA for ML, DC, and (CFU,log/mg). Tukey's post-hoc test (α = 0.05) for multiple comparison was applied. Results: The addition of CuZnONps in the adhesive led to a significant reduction in CFU count for both mutans streptococci

and total fungus (p <0.05). SEM imaging showed biofilm with complex three- dimensional morphology, primarily cocci and streptococci. The addition of CuZnO

significantly decreased ML at 20 μm (p=0.0002), 50 μm (p=0.0000002), and 100 μm (p= 0.000001). After CC, all groups in the ER strategy, significantly decreased the μTBS values compared to (IM) values (p < 0.002). No significant difference in μTBS values for the SE CuZnO at IM and after CC was observed (p> 0.05). DC values showed no significant differences on all groups (p= 0.29). NL values of control significantly increased compared CuZnO after CC, regardless of the adhesive strategy. Conclusion: The addition of CuZnONps (0.2/5 wt%) into a universal adhesive may provide a local antimicrobial activity and reduce mineral loss, increasing its bonding properties under a cariogenic environment.