Bioactivities of a SiO₂-CaO-ZrO₂ Glass in Simulated Body Fluid and Human Parotid Saliva

Influence of thermal treatment on the "in vitro" bioactivity of wollastonite materials

The aim of this work was to study the influence of the composition and thermal treatment of the in vitro bioactivity of wollastonite materials obtained by sol-gel method. For this purpose, gels in the system SiO(2)-CaO were obtained applying calcium nitrate and tetraethoxysilicate as precursors. The gels were heated to 700 °C and then sintered up to 1400 °C. The bioactivity of the gel-derived materials in simulated body fluid (SBF) was investigated and characterized. Additional changes in ionic concentration, using inductively couple plasma atomic emission spectroscopy (ICP-AES), were determined. The results showed that all materials obtained were bioactive and indicate that the absence of phosphorous in the material composition is not an essential requirement for the development of a Hydroxyapatite layer. The bioactivity was influenced by the thermal treatment, the different phases (glass-phase, wollastonite and pseudowollastonite) as well as the porous size. On the gel-derived materials the bioactivity decreased with the sintering temperature.

The effect of simulated body fluid on the mechanical properties of multiblock poly(aliphatic/aromatic-ester) copolymers

The effects of simulated body fluid (SBF) on the surface and mechanical properties of poly(aliphatic/aromatic-ester) (PED) copolymers were investigated. PED copolymers containing different hard (aromatic) and soft (aliphatic) segment weight ratios were exposed to SBF for 52 days, and afterwards their mechanical properties were evaluated. A quasi-static tensile test estimating relaxation and fatigue properties from the hysteresis method was performed. The surface properties were monitored with scanning electron microscopy and energy-dispersive X-ray spectrometry. PED copolymers showed various susceptibilities to apatite layer formation on the surface. This was ascribed to the hard/soft segment ratios of PED materials. Polymers containing higher amounts of amorphous soft segments showed a better deposition with the apatite layer, which provided improved mechanical properties, especially fatigue (improved dynamic creep resistance).