The effect of adding organic polymers on the handling properties, strengths and bioactivity of a Ca-Sr-Zn-Si glass polyalkenoate cement

This work demonstrates the addition of a number of naturally occurring proteins/polymers to a Zinc based Glass Polyalkenoate Cements (GPCs). Chitin (Chi.) Collagen (Col.), Cysteine (Cys.) and Keratin (Ker.) were added with the intention of improving the bioactivity of this cement. Initial testing involved characterization of the glass with X-ray Diffraction (XRD) and Differential Thermal Analysis (DTA) before and after sterilization with γ-irradiation. No significant changes occurred as a result of sterilization. Handling properties of the modified cements were not significantly different from those of the control, BT 101 (Working Tw - 36s, and Setting time Ts - 70s) except for Chi. (30s, p≤0.016) and Cys. (105s, p≤0.0001) respectfully. Comparison of the mechanical properties of BT 101 (compression - σc and biaxial flexural - σf) to the modified cements revealed a significant decrease in σc with Chi. and Col., after 1, 7 and 30 days. However, there were little changes occurring in σf. Cement structural testing was investigated and found that the addition of these polymers greatly reduced the cements surface area, however the only significant change to occur in the solubility testing was Ker. (p≤0.009). Simulated Body Fluid (SBF) testing resulted in increased calcium phosphate (CaP) deposition of Chi. and Col. compared to BT 101. Cell culture studies determined only Col. significantly increased (p≤0.0001) in comparison to the control cement.