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Influence of Ta2O5 doping on mechanical and biological properties of silicate glass-ceramics

Riaz M., Zia R., Saleemi F., Bashir F., Ahmad R., Hossain T.

Materials Science Poland

2016

Vol. 34, No. 1

13--18

The mechanical properties of silicate glass-ceramics were evaluated based on the compressive strength tests. It was found that addition improved densification, refinement of the microstructure and toughening of the bodies. The maximum compressive strength of the bodies with 1 mol% Ta2O5 was increased 3-fold (245.92 ±0.3 MPa) in comparison to undoped glass-ceramics which was measured to be 89.04 ±0.3 MPa, while for 3 mol% it became 4-fold (387.12 ±0.4 MPa) greater. The addition of Ta2O5 stabilized the system by controlling the biodegradation of the glass-ceramics. It effectively depressed the apatite formation as by addition of 3 mol% Ta2O5 no apatite layer was observed. It may be concluded from this study that mechanical and physical properties can be improved by the addition of Ta2O5 , but at a cost of bioactivity. Still the optimized composition having Ta2O5 ≤ 1 mol% may provide appropriate strength of biomaterials for high load bearing applications.

In vitro evaluation of bioactivity of SiO2-CaO-P2O5-Na2O-CaF2-ZnO glass-ceramics

Riaz M, Zia R, Saleemi F, Bashir F, Hossain T, Kayani Z

Materials Science Poland

2014

Vol. 32, No. 3

364--374

Zinc is an essential trace element that stimulates bone formation but it is also known as an inhibitor of apatite crystal growth. In this work addition of ZnO to SiO2–CaO–P2O5–Na2O–CaF2 glass-ceramic system was made by conventional meltquenching technique. DSC curves showed that the addition of ZnO moved the endothermic and exothermic peaks to lower temperatures. X-ray diffraction analysis did not reveal any additional phase caused by ZnO addition and showed the presence of wollastonite and hydroxyapatite crystalline phases only in all the glass-ceramic samples. As bio-implant apatite forming ability is an essential condition, the surface reactivity of the prepared glass-ceramic specimens was studied in vitro in Kokubo’s simulated body fluid (SBF) [1] with ion concentration nearly equal to human blood plasma for 30 days at 37 °C under static condition. Atomic absorption spectroscopy (AAS) was used to study the changes in element concentrations in soaking solutions and XRD, FT-IR and SEM were used to elucidate surface properties of prepared glass-ceramics, which confirmed the formation of HCAp on the surface of all glass-ceramics. It was found that the addition of ZnO had a positive effect on bioactivity of glassceramics and made it a potential candidate for restoration of damaged bones.