Avaliação da influência de nanopartículas e micropartículas de Nb2O5 em adesivo odontológico modelo.

Abstract

The radiopacity is an important property of adhesive systems, because it allows the adhesive contrast with tooth structure and other restorative materials. However, the available commercial adhesives do not have sufficient radiopacity to be detected in radiographs. In this sense, the purpose of this study was to evaluate the influence of niobium pentoxide (Nb2O5) particles in a dental adhesive resin model in order to obtain a radiopaque dental adhesive. Nb2O5 microparticles commercial (optical grade) and Nb2O5 nanoparticles synthesized by microwave-assisted hydrothermal synthesis (MHS) were evaluated. The synthesis of Nb2O5 nanoparticles was carried out at different times (15, 30 and 60minutes) and these were characterized by transmission electron microscopy (TEM), Raman spectroscopy and, X-ray diffraction (XRD). The adhesive resin model was obtained by mixing bisphenol A glidicil methacrylate (Bis-GMA), 2-hydroxyethyl methacrylate (HEMA), camphorquinone (CQ) and ethyl 4-dimethylaminobenzoate (EDAB). Nb2O5 nanoparticles and microparticles were added in adhesive resin model at different concentrations (0%, 10% and 20% by weight). The adhesive resins formulated were evaluated as to radiopacity, translucency, degree of conversion, depth of cure, viscosity, sedimentation rate, Knoop microhardness, flexural strength and modulus of elasticity. Quantitative data were subjected to analysis of variance (ANOVA) and Tukey test with 5% level of significance. The analyses showed that the Nb2O5 nanoparticles synthesized have hexagonal structure, rounded shape covered by nanoneedles and average particle size between 20 and 50nm. Nb2O5 microparticles commercial exhibited orthorhombic structure and average particle size 20,26μm. Radiopacity and viscosity of the adhesive resin increased with the incorporating particles, however the translucency, flexural strength and modulus decreased. Degree of conversion of M10% and N10% groups was higher than 50%, while that the depth of cure of M10%, M20% and N10% groups was over than 1mm. The speed sedimentation of the microparticles dispersed in the adhesive resin was remarkably superior to nanoparticles, while there was no difference in the microhardness of different adhesive groups. The incorporation of Nb2O5 particles in dental adhesive resin showed desired radiopaque properties and they proved to be a promising alternative for the application of biomaterials based on polymers.