Strong, Macroporous, and in Situ-Setting Calcium Phosphate Cement Layered Structures

Published

May 26, 2007

Author(s)

Hockin D. Xu, Lisa E. Carey, Elena F. Burguera

Abstract

Calcium phosphate cement (CPC) is highly promising for clinical uses due to its in situ-setting ability, excellent osteoconductivity and bone-replacement capability. However, the low strength limits its use to non-load-bearing applications. The objectives of this study were to develop a layered CPC structure by combining a macroporous CPC layer with a strong CPC layer, and to investigate the effects of porosity and layer thickness ratios. The rationale was for the macroporous layer to accept tissue ingrowth, while the fiber-reinforced strong layer would provide the needed early-strength. A biopolymer chitosan was incorporated to strengthen both layers. Flexural strength, S, (mean sd; n = 6) of CPC-scaffold decreased from (9.7 1.2) MPa to (1.8 0.3) MPa (p < 0.05), when the porosity increased from 44.6 % to 66.2 %. However, with a strong-layer reinforcement, S increased to (25.2 6.7) MPa and (10.0 1.4) MPa, respectively, at these two porosities.These strengths matched/exceeded the reported strengths of sintered porous hydroxyapatite implants and cancellous bone. Relationships were established between S and the ratio of strong layer thickness/specimen thickness, a/h: S = (17.6 a/h + 3.2) MPa. The scaffold contained macropores with sizes ranging from 100 m to 300 m, suitable for cell infiltration and tissue ingrowth. Nano-sized hydroxyapatite crystals were observed to form the scaffold matrix of CPC with chitosan. In summary, a layered CPC implant, combining a macroporous CPC with a strong CPC, was developed. The effects of porosity and layer thickness ratios were determined. Relatively high strength and porosity were simultaneously achieved. Such an in situ-hardening, nano-apatite implant may be useful in moderate stress-bearing applications, with macroporosity to enhance tissue ingrowth and implant resorption.

Citation

Biomaterials

Volume

28

Pub Type

Journals

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Keywords

bone repair, calcium phosphate cement, hydroxyapatite, layered structure, strength macroporosity, Dentistry

Citation

Xu, H. , Carey, L. and Burguera, E. (2007), Strong, Macroporous, and in Situ-Setting Calcium Phosphate Cement Layered Structures, Biomaterials, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=852723 (Accessed July 27, 2024)