RESUMO
OBJECTIVES: The objective was to investigate the mechanical properties, fluoride release and apatite formation of resin based dental composites based on a fluoride containing Bioactive Glass (BG) with and without a silylating agent. METHODS: A SiO2-P2O5-CaO-SrO-Na2O-CaF2 BG was synthesized by the melt quench route. This glass and a commercially available inert glass (IG) were incorporated into a light cured BisGMA-TEGMA resin. The composite resins were then evaluated in terms of their ability to form apatite by Fourier Transform Infrared spectroscopy (FTIR) and by scanning electron microscopy (SEM) following immersion in artificial saliva at pH 4 (AS4) and pH 7 (AS7). The experiments were performed with and without silylation of the BG. The compressive strength and flexural strength were determined after 1, 28 and 84 days of immersion in the AS4 and AS7 immersion media. RESULTS: The FTIR spectra of the BG composites exhibited split bands at approximately 560 and 600 cm-1 corresponding to a apatite formation in the surface or on the surface under all immersion conditions. SEM showed the presence of a reacted layer of glass particles in the composite surface and the presence of a surface layer of apatite in AS7. The compressive strength and flexural strength were significantly higher for the silylated BG composites. The strengths of both silylated and non silylated BG composites and IG composites decreased upon immersion. SIGNIFICANCE: BG composites exhibit reduced strengths upon immersion but still exhibit strengths comparable to existing composites after 84 days of immersion.
