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Strong and Bioactive Composites Containing Nano-Silica-Fused Whiskers for Bone Repair



H H. Xu, Douglas T. Smith, Carl Simon Jr.


Self-hardening calcium phosphate cement (CPC) sets to form hydroxyapatite with high osteoconductivity, but its brittleness and low strength prohibit use in stress-bearing locations. Bioactive composites containing hydroxyapatite fillers in polymer matrices have higher strengths, but they are still lower than the strength of cortical bone. The aim of this study was to develop strong and bioactive composites by combining CPC fillers with nano-silica-fused whiskers in a resin matrix, and to characterize the mechanical properties and cell response. Silica particles were fused to silicon carbide whiskers to roughen the whisker surfaces for enhanced retention in the matrix. Mass ratios of whisker:CPC of 1:2, 1:1 and 2:1 were incorporated into a Bis-GMA-based resin and hardened by two-part chemical curing. Composite with only CPC fillers without whiskers served as a control. The specimens were tested using three-point flexure and nano-indentation.Composites with whisker:CPC ratios of 2:1 and 1:1 had flexural strengths (mean SD; n = 9) of (164 14) MPa and (139 22) MPa, respectively, nearly three times higher than (54 5) MPa of the control containing only CPC fillers (p < 0.05). The mechanical properties of the CPC-whisker composites nearly matched those of cortical bone and trabecular bone. Osteoblast-like cell adhesion, proliferation and viability were equivalent on the non-whisker control containing only CPC fillers, on the whisker composite at whisker:CPC of 1:1, and on the tissue culture polystyrene control, suggesting that the new CPC-whisker composite is biocompatible.
No. 19


bioactive composite, bone repair, calcium phosphate cement, elastic modulus, nano-silica shisker fusion, strength


Xu, H. , Smith, D. and Simon Jr., C. (2004), Strong and Bioactive Composites Containing Nano-Silica-Fused Whiskers for Bone Repair, Biomaterials, [online], (Accessed April 17, 2024)
Created July 31, 2004, Updated October 12, 2021