Effect of FA on bioactivity of bioactive glass coating for titanium dental implant. Part I: Composite powder

Abstract In orthopedics and dentistry bioactive glasses are a suitable material to improve the bone-bonding ability of titanium implants. Yet, these glasses have high thermal expansion coefficients. Attempts have been made to reduce the thermal expansion coefficient of these glasses by incorporating oxides such as MgO into glass composition. However, it has been shown that this retards the glass bioactivity. Therefore, mixing fluorapatite (FA) with bioactive glasses has been carried out to speed up the process of surface apatite formation, without modifying the glass composition. In this study we investigate the effect of fluorapatite crystals at two loadings on the bioactivity of glasses containing 9.9, 16.1 and 22.1 mol% MgO. These glasses have been synthesized by a melt-derived route. These glass compositions contain SiO2, CaO, MgO, MgF2, Na2O, K2O and P2O5. FA crystals were produced by solid state reaction. The glass powder was mixed with FA at two ratios by weight (4:1 and 14:1). The composite powder was characterized by X-ray diffraction and Fourier transform infrared spectroscopy. The bioactivity of the composite (glass/FA) powder of the two series was assessed in Tris-buffer solution at two time points. The immersed composite powder was investigated by XRD and FTIR, and the filtrates were analyzed using inductively coupled plasma spectroscopy and fluoride-selective electrode. The results indicate that FA additions can enhance and improve the apatite forming ability of the original glass powder.