Efeito do acréscimo de nanopartículas radiopacas no desempenho de um sistema adesivo experimental autocondicionante livre de Hema

Abstract

The aim of this study was to develop a nanostructured adhesive system, two-step self-etch, with high performance and radiopacity property. Selfething-primers were formulated by mixing GDMA-P, HEMA or PEG 400 UDMA, ethanol and water. The resin adhesives were formulated with Bis-GMA, TEGDMA, HEMA or PEG 400 UDMA, CQ and EDAB, besides ytterbium fluoride (YbF3) or silica (SiO2) nanoparticles were added. The adhesives were analyzed using degree of conversion, radiopacity, refractive index, flexural strength, flexural modulus, water sorption and solubility tests. The bond strength to dentin after 24h and 6 months of water storage was also performed. Data were statistically analyzed using ANOVA and Tukey test (α=5%). The minimal concentration in mass of 20% was necessary for the PEG 400 UDMA-based adhesives become radiopaque, and of 30% for the HEMA-containing adhesives. In the overall analysis, the physical properties investigated were maintained or improved by addition of nanoparticles. The adhesion to dentin after 6 months of water storage was negatively affected within the SiO2-based groups, but YbF3 hampered the adhesion degradation within the HEMA-containing adhesive, although within the PEG 400 UDAM-based adhesive it resulted in decrease of microtensile bond strenght. The incorporation of nanofillers into dental adhesives seems to be an interesting way to achieve enhanced properties, although the domain of this technology still needs further further studies to better understand the effect of incorporation of fillers and/or with their surface treatment.