The effect of high tempered firing cycle on the bioactive behavior of sol-gel derived dental porcelain modified by bioactive glass

The purpose of the present study was to investigate the influence of end-temperature over the structural properties, chemical composition and bioactivity of dental porcelain modified by bioactive glass. In particular, sol-gel derived specimens of bioactive glass dental porcelain underwent firing at two increased end-temperatures. All specimens were characterized using Scanning Electron Microscopy, Fourier Transform Infrared and Raman Spectroscopy, X-ray diffraction and N_2-porosimetry. In vitro bioactivity test was performed too. SEM analysis of both specimens revealed smooth morphology of particles, which were sintered together. Spherical and closed porei were evident. N_2- adsorption isotherms of specimens represented non nano-/meso-porous materials. FTIR and Raman spectroscopy revealed the predominance of b-wollastonite as well as the appearance of a-cristobalite. XRD confirmed the results. In vitro tests evidenced the bioactivity of the specimens regardless of temperature. However, the increased temperature caused delayed apatite precipitation. In conclusion, increased temperature favored the sintering process initiation, along with the surface crystallization, which in turn delayed bioactivity.