| 0306 Culturing osteoblasts on titanium enhances biomechanical properties of mineralized tissue | ||
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L. SARUWATARI1, F. BUTZ1, H. AITA1, N. OHNO2, and T. OGAWA1, 1University of California Los Angeles, USA, 2Aichi-Gakuin University, School of Dentistry, Nagoya, Japan Objective: The biological mechanisms underlying bone-titanium integration and its biomechanical performance are poorly understood. The objective of this study is to determine intrinsic biomechanical properties and interfacial strength of cultured mineralized tissue on titanium and examine the microstructure as possible contributing factors in biomechanical modulation. Methods: Rat bone marrow-derived osteoblastic cells were cultured either on polystyrene dish or titanium coated polystyrene. Nanoindentation and nano-scratch tests were undertaken on mineralized tissues cultured for 28 days to evaluate its hardness, elastic modulus and critical load (force to delaminate tissue). Steady-state gene expression was analyzed using RT-PCR. Mineralized tissue structure and phenotype were examined by scanning electron microscopy (SEM), collagen colorimetry and localization with Sirius red stain, and mineral quantification and localization with Von Kossa stain. Results: Hardness and elastic modulus of mineralized tissue on titanium was 3 times and 2 times greater, respectively, than on the polystyrene. SEM of the polystyrene culture displayed a porous structure consisting of fibrous and globular components, while the titanium tissue culture appeared to be uniformly solid. Cross-sectional histology revealed that the mineralized tissue on titanium was composed of uniform collagen-supported mineralization from the titanium interface to the outer surface, and intensive collagen deposition at tissue-titanium interface, while the tissue on the polystyrene was characterized by collagen-deficient mineralization at the polystyrene-interface and calcium-free collagenous matrix formation in the outer tissue area. Such distinctive microstructure of titanium-associated tissue was supported by upregulated gene expression of collagen I and III, osteopontin and osteocalcin genes. Conclusions: Culturing osteoblasts on titanium enhances hardness, elastic modulus and interfacial strength of mineralized tissue, together with distinctive tissue micro-structure characterized by uniform mineralization and intense collagen deposition. Titanium per se possesses an ability to alter cellular and tissue phenotypes that result in enhanced intrinsic biomechanical properties of mineralized tissue. | ||
| Seq #64 - Cellular Response to Implant Interface 10:45 AM-12:45 PM, Thursday, 10 March 2005 Baltimore Convention Center 329 | ||
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