Biomedical Engineering and Bioengineering Commons^™

Preliminary In Vivo Studies Of A New Injectable Bone Substitute, F. Millot, G. Grimandi, P. Weiss, G. Daculsi

Cells and Materials

Calcium-phosphate materials have been increasingly employed in orthopedic and dental applications in recent years and are now being developed for use in noninvasive surgery or as carriers for drug delivery systems. We developed an injectable bone substitute (IBS) for percutaneous orthopedic surgery which uses a biphasic calcium-phosphate (BCP) mixture composed of hydroxyapatite (60%) and ß-tricalcium phosphate (40%), together with a polymer (hydroxy-propyl-methyl-cellulose, HPMC) as a carrier. The best BCP/polymer ratio was determined to achieve the highest mineral phase in the composite and provide the rheological properties required for injectable material.

The in vivo biocompatibility and biofunctionality of IBS were …

Biomimetic Habitats For Cells: Ordered Matrix Deposition And Differentiation In Gingival Fibroblasts Cultured On Hydroxyapatite Coated With A Collagen Analogue, Rajendra S. Bhatnagar, Jing Jing Qian, Anna Wedrychowska, Eric Dixon, Nancy Smith

Cells and Materials

In tissues, cells attach and migrate on collagen. Interaction with collagen modulates cell proliferation and differentiation. We propose that similar environments may be constructed by immobilizing collagen-derived cell-binding peptides in a three-dimensional (3-D) template. We identified a cell binding domain of type I collagen and showed that a 15-residue synthetic analogue (P-15) binds cells with high affinity. In the present study, we compared the behavior of human gingival fibroblasts (HGF) in culture on hydroxyapatite (HA) and on HA-P-15. HGF cultured on HA formed sparse monolayers with little order and deposited a scant matrix. HGF on HA-P-15 formed highly oriented 3-D …

The Role Of Surface Roughness For Implant Incorporation In Bone, A. Wennerberg

Cells and Materials

A careful topographical characterization is important for reliable interpretation of the role of implant surface roughness in bone incorporation. In this paper, the currently available measuring instruments and evaluation techniques are described and discussed first, than literature on the role of surface roughness for cell and bone tissue reactions in vitro and, with special emphasis, the in vivo studies are reviewed. Finally, the results from a series of the authors own animal studies evaluating screw-shaped implants with different surface roughnesses are summarized. The results demonstrated firmer bone fixation for blasted implants than for turned ones. A blasted surface with an …

Behavior Of Melanoma Cells In Cell And Organ Cultures: Use Of Biomaterials To Activate Cells, J. L. Duval, N. Faucheux, R. Warocquier-Clérout, M. D. Nagel

Cells and Materials

It is well known that cell behaviors such as adhesion, proliferation and various synthesis are initiated from transmembrane signals. This study uses biomaterials as primary messengers of the cell activation pathways, and we have analyzed the effects of two biomaterials on highly metastatic tumor cells. B16F10 melanoma cells formed heterogeneous populations whose size varied with cell differentiation. In long-term organ cultures grown comparatively on AN 69 and Cuprophan (a biomembrane known to activate cells), we found that Cuprophan increased both adhesion and proliferation of small melanin-rich cells which represented differentiated melanocyte&. In dissociated cell cultures, the rate of early cell …

Mechanical Properties Of Dendritic Pd-Cu-Ga Dental Alloys, Efstratios Papazoglou, Qiang Wu, William A. Brantley, John C. Mitchell, Glyn Meyrick

Cells and Materials

Three Pd-Cu-Ga dental alloys with very similar nominal compositions and dendritic as-cast microstructures were selected for study: Option (Ney Dental) and Spartan (Williams/lvoclar) contain a small amount of boron, while Spartan Plus (Williams/Ivoclar) is boron-free. Bars of each alloy were tested in tension for the as-cast and simulated porcelain-firing conditions, and values of mechanical properties were measured. Fracture surfaces and microstructures of axially sectioned and etched fracture specimens were observed with the scanning electron microscope (SEM). Except for the elastic modulus, significant differences were typically found in alloy properties. Heat treatment eliminated the dendritic microstructure, decreased strength and increased ductility. …

X-Ray Diffraction And Scanning Electron Microscopy Analyses Of A Gallium-Based Dental Restorative Alloy, Randa E. Shaker, William A. Brantley, Qiang Wu, John C. Mitchell

Cells and Materials

Specimens of a gallium-based dental alloy were prepared with different condensation techniques, with and without the removal of a surface layer, and after aging for 2 hours at 50°, 100° and 150°C. X-ray diffraction at times ranging from 10 minutes to 1 day showed the development of the four matrix phases (ß-Sn, CuGa₂, Ga₂₈Ag₇₂, and In₄Ag₉) during the setting reaction. Scanning electron microscope (SEM) examination of specimens loaded to failure revealed brittle fracture, with greater porosity for hand-condensed specimens, and provided insight into crack propagation processes. Aging increased …

Formation Of Cement Lines, But Not Laminae Limitantes, Requires Contact Of Differentiating Osteogenic Cells To Solid Surfaces, M. M. Hosseini, A. Shiga, J. E. Davies

Cells and Materials

We designed in vitro experiments to address the hypothesis that cement lines and laminae limitantes are structurally distinct as a result of cell contact, or absence of cell contact, during their elaboration. We subcultured young adult primary rat bone marrow cells in well inserts with polycarbonate membranes of 0.45 µm pore size, which allowed protein but not cell passage. The cells, extracellular matrix, lower side of the membrane and the surface of the polystyrene culture well were examined by scanning and transmission electron microscopy. The cells elaborated a bone-like matrix on top of the membrane. In such cultures the …

Quantifying The Surface Geometry Of Titanium Implant Material By Different Methods Of Analysis, Clara Pimienta, Rashad Tawashi

Cells and Materials

Biomaterial implant manufacturers have used rough surfaces to ensure better biocompatibility, less rejection and better adaptation of implants in the body. Proper characterization of biological interactions and biocompatibility of biomaterials requires a thorough understanding of surface complexity. Surface roughness has often been shown to be important in influencing biological reactions with the surface. Previous communications from our laboratory have described a dynamic active vision system (MVS camera) capable of measuring three-dimensional coordinates of titanium implant material surfaces. Fractal analysis, due to its straightforward relationship to texture, is used to characterize the degree of irregularity of a surface and is expressed …

Effects Of Casting Conditions And Annealing On Microstructures And Vickers Hardness Of Dendritic Pd-Cu-Ga Dental Alloys, William A. Brantley, Qiang Wu, Zhuo Cai, Stanley G. Vermilyea, John C. Mitchell, Michael C. Comerford

Cells and Materials

Three Pd-Cu-Ga alloys with as-cast dendritic microstructures and very similar compositions, two containing less than 1 wt% boron and the third boron-free, were cast with normal bench-cooling or rapid-quenching into water. Quenched specimens were also heat treated at temperatures of 1000°, 1200°, 1500° and 1800°F that span the firing cycles for dental porcelain. Similar values of Vickers hardness were observed for all three alloys, suggesting little effect from boron on yield strength. The hardness was relatively insensitive to the experimental conditions, except for heat treatment at 1500° and 1800°F where significant softening occurred with transformation of the microstructure to Pd …

In Vitro Comparative Biocompatibility Testing Of Carbofilm Coated And Uncoated Polyetherimide For Cardiovascular Application, M. Bosetti, S. Mazzarelli, L. Nicolais, L. Ambrosio, M. Cannas

Cells and Materials

When blood contacts the surface of a material, several processes take place including the activation of coagulation and immune systems. The aim of this work is to study in vitro the biological reactions seen from the point of view of hemocompatibility and cytocompatibility of a new polymer suggested as an artificial surface for cardiovascular applications: Carbofilm® coated polyetherimide (C®PEI) in comparison to polyetherimide (PEI), the uncoated form. PEI and C®PEI showed no signs of acute cytotoxicity although following long term incubation with PEI cytotoxicity was somewhat increased; both materials supported good endothelial cell adhesion with a higher level of cell …

Image Analysis And The Effect Of Molecular Orientation On Degrading Lactide Polymer Films, K. J. L. Burg, M. Laberge, D. L. Powers, S. W. Shalaby

Cells and Materials

Absorbable polylactide films were studied in order to observe the effect of orientation on the resulting hydrolytic degradation pattern. Two types of polylactide films with two levels of molecular orientation were studied, during a nine month exposure to a phosphate buffered solution at 37°C. The films were sectioned and quantified as to void area, birefringence area, and intensity of birefringence using a microscope and an image analysis software package. The results, obtained using an analysis of variance, showed that the orientation played a significant role in the degradation pattern of the polylactide films, either decreasing or causing no change in …