Zirconia/bioactive glass composites development through a particle nanocoating

Abstract

Zirconia based materials are widely used as dental materials because of their good mechanical properties and aesthetic, but there is a need of enhancing its biological response for clinical use. In that sense, a bioactive glass is added to zirconia matrix with the aim of improving the material biocompatibility. The effect of the raw powders synthesis method for dense zirconia/bioactive glass biomaterials was investigated. Two paths were developed to obtain zirconia-based composites with 2.5, 5 and 10 wt% addition of a bioactive glass (referred as 64S): the traditional powder mixture method, and a core-shell powder through sol-gel particle nanocoating. Particle size distribution and SEM images were performed for the powders characterization. Sol-gel coating was analyzed with TEM images and FT-IR spectra. The sintering process was studied with an optical dilatometer up to 1450 °C, and the density of the samples was calculated with the Archimedes method, in the range of 1100–1500 °C. The final crystalline phases were studied with Rietveld quantification through XRD analysis and the microstructure with SEM/EDS analysis. Vickers indentation method was used to evaluate the hardness. Biological properties were studied with murine fibroblast cell line L929 and were analyzed by fluorescence microscopy. Results showed that samples obtained by the sol-gel particle coating method enhanced the sintering process, with a sintering temperature in the range 1300–1400 °C; they showed a more homogeneous and pore-free microstructure with a higher retention of the t-ZrO2 phase after cooling, in comparison with the samples obtained by the powder mixture method. The Vickers hardness of composites obtained by the core-shell particles had values above 11 GPa, and composites with 2.5 and 5 wt% 64S, sintered at 1400 °C, presented Vickers values of ∼13 GPa. Furthermore, biocompatibility was promoted with the addition of 64S glass, independently of the raw powders synthesis method.