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Full-Text Articles in Biomedical Engineering and Bioengineering

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 Jan 1999

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 ...


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 Jan 1999

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 ...


In Vitro Comparative Biocompatibility Testing Of Carbofilm Coated And Uncoated Polyetherimide For Cardiovascular Application, M. Bosetti, S. Mazzarelli, L. Nicolais, L. Ambrosio, M. Cannas Jan 1999

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 ...


Preliminary In Vivo Studies Of A New Injectable Bone Substitute, F. Millot, G. Grimandi, P. Weiss, G. Daculsi Jan 1999

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 ...


Mechanical Properties Of Dendritic Pd-Cu-Ga Dental Alloys, Efstratios Papazoglou, Qiang Wu, William A. Brantley, John C. Mitchell, Glyn Meyrick Jan 1999

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 ...


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 Jan 1999

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 ...


The Role Of Surface Roughness For Implant Incorporation In Bone, A. Wennerberg Jan 1999

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 ...


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 Jan 1999

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 ...


Quantifying The Surface Geometry Of Titanium Implant Material By Different Methods Of Analysis, Clara Pimienta, Rashad Tawashi Jan 1999

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 ...


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 Jan 1999

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 the amount of ...


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 Jan 1999

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 ...


Alloy Oxidation And Porcelain Fused To Alloy Interaction In Noble Alloy Systems, M. S. Bapna, H. J. Mueller Jan 1997

Alloy Oxidation And Porcelain Fused To Alloy Interaction In Noble Alloy Systems, M. S. Bapna, H. J. Mueller

Cells and Materials

The oxidation and porcelain fusion characteristics of noble alloys containing a variety of minor oxidizable elements, including Cu, Sn, In, Ga, Mn, and Fe were investigated. Four porcelain alloys systems: a Pd-base alloy (Naturelle}, two Pd-Ag-based alloys (Jelstar and Acclaim}, and a high Au-alloy (SMG-3) were examined by scanning electron microscopy and energy dispersive spectroscopy after being heat treated and after being fused with porcelain. Internal oxidation of minor alloying elements occurred within several micrometers from the surface in all four alloys. Surface nodules as detected by other investigators for a Pd-Ag alloy were also detected in this study. Evidence ...


Transmission Electron Microscopical Study Of Fibroblast Attachment To Microtextured Silicone Rubber Surfaces, E. T. Den Braber, J. E. De Ruijter, H. J. E. Croes, L. A. Ginsel, J. A. Jansen Jan 1997

Transmission Electron Microscopical Study Of Fibroblast Attachment To Microtextured Silicone Rubber Surfaces, E. T. Den Braber, J. E. De Ruijter, H. J. E. Croes, L. A. Ginsel, J. A. Jansen

Cells and Materials

Cellular attachment has been suggested to be highly influenced by the micromorphology of the substratum surface. To test this hypothesis, smooth and microtextured silicone substrata were produced, which possessed parallel surface grooves with a groove and ridge width of 2.0 (SilD02), 5.0 (SilD05), and 10 µm (SilD10). Groove depth was approximately 0.5 µm. After culture of rat dermal fibroblasts (RDFs) on these substrata for 3 and 5 days, the samples were prepared and sectioned for transmission electron microscopy with a specially developed preparation technique. On the SilD02 and SilD05 surfaces, it was found that the ...


A Novel In Vitro Model To Study The Calcification Of Biomaterials, Q. Liu, J. Weng, J. G. C. Wolke, J. R. De Wijn, C. A. Van Blitterswijk Jan 1997

A Novel In Vitro Model To Study The Calcification Of Biomaterials, Q. Liu, J. Weng, J. G. C. Wolke, J. R. De Wijn, C. A. Van Blitterswijk

Cells and Materials

A novel in vitro model based on a solution mainly composed of sodium, calcium, chloride and phosphate ions, was developed to study the calcification of biomaterials at near physiological conditions. This model, due to its ability to quickly calcify the tested materials, is called Accelerated Calcification Solution (ACS). Polyactive ™ 30170, Polyactive™ 70/30 and its composites with nano-apatite were used as testing materials because of their known calcification behaviour. The results showed that Polyactive™ 70/30 and its composites could calcify in ACS in a relatively short period, while the polymer without filler failed to induce calcium phosphate precipitation in ...


Sintered Carbonate Apatites As Bone Substitutes, Yutaka Doi Jan 1997

Sintered Carbonate Apatites As Bone Substitutes, Yutaka Doi

Cells and Materials

Sintering of carbonate apatites was investigated and the usefulness of sintered specimens as bone substitutes was evaluated in vitro and in vivo. Osteoclasts appeared to be capable of resorbing sintered carbonate apatite, which was as soluble as deproteinated bone and much more soluble than sintered hydroxyapatite in weak acids. In skull defects of Wistar rats, sintered carbonate apatite particles resorbed to an appreciable extent, but the rate of resorption did not exceed that of new bone formation. At 4 weeks after implantation the defects were filled almost completely with new bone that compared favorably with the host bone. These findings ...


Surface Modifying Additives Reduce Thrombogenicity: An In Vitro And Clinical Evaluation, H. T. Spijker, J. Haan, R. Graaff, P. W. Boonstra, W. Van Oeveren Jan 1997

Surface Modifying Additives Reduce Thrombogenicity: An In Vitro And Clinical Evaluation, H. T. Spijker, J. Haan, R. Graaff, P. W. Boonstra, W. Van Oeveren

Cells and Materials

To improve the biocompatibility of biomaterials a new surface treatment has been described based on the addition of polysiloxane containing copolymers to the base polymer resin (surface modifying additives). In an in vitro and a clinical study, we compared the thrombogenicity of polyvinyl chloride (PVC) to PVC with these surface modifying additives (SMA).

In the in vitro study, adsorption of thrombin and fibrinogen, binding of platelets and platelet release were measured on the tubing and were found reduced on SMA-PVC.

For the clinical study, we examined tubing material and blood collected after cardiopulmonary bypass (CPB). Onto the tubing, the binding ...


Osteoclast Differentiation In Cocultures Of Chondrogenic Cell Line Rcj 3.1c5.18 And Mouse Or Rat Bone Marrow: Dependence On Culture Substrate And Association With Alkaline Phosphatase Positive Marrow Stromal Cells, G. I. Anderson, J. N. M. Heersche Jan 1997

Osteoclast Differentiation In Cocultures Of Chondrogenic Cell Line Rcj 3.1c5.18 And Mouse Or Rat Bone Marrow: Dependence On Culture Substrate And Association With Alkaline Phosphatase Positive Marrow Stromal Cells, G. I. Anderson, J. N. M. Heersche

Cells and Materials

We investigated the formation of tartrate-resistant acid phosphatase positive (TRAP+) colonies and multinucleated cells (MNCs) in rat and mouse marrow cultures alone and cocultured with the chondrogenic cell line, RCJ3.1C5.18 on different substrata. In mouse marrow cultured in 35 mm dishes, few TRAP+ MNCs developed, while in rat marrow cultures, many TRAP+ MNCs, which possessed calcitonin receptors and resorbed bone, developed. In both rat and mouse cultures, TRAP+ MNC first appeared at Day 4 and grew in number up to Day 8. When both marrows were cocultured with RC3.1C5.18 cells, TRAP+ colony numbers increased relative to ...


Ultrastructural Observations Of Peri-Implant Mucosa Morphology Around Different Types Of Abutment In Humans, C. Piacentini, P. Lanzarini, R. Rodriguez Y Baena, S. Rizzo, C. Brusotti Jan 1997

Ultrastructural Observations Of Peri-Implant Mucosa Morphology Around Different Types Of Abutment In Humans, C. Piacentini, P. Lanzarini, R. Rodriguez Y Baena, S. Rizzo, C. Brusotti

Cells and Materials

Scanning electron microscopy (SFM) and transmission electron microscopy (TEM) were used to examine the morphological aspects of peri-implant mucosa around abutments of differing geometry (biconical and cylindrical) and of differing surface micromorphology. The samples were taken from seven patients who had undergone implant surgery at least one year prior to the study. In samples from biconical abutments, SEM of the sulcular epithelium showed that it consisted of flattened polygonal cells with a surface resembling a honeycomb. Superficial desquamation was rarely found. In contrast, in the samples from cylindrical abutments, the sulcular epithelium showed extensive desquamation and surface irregularity, but not ...


Mechanism For Formation Of Lamellar Constituents In Grain-Refined Pd-Cu-Ga Dental Alloys, William A. Brantley, Zhuo Cai, John C. Mitchell, Stanley G. Vermilyea Jan 1997

Mechanism For Formation Of Lamellar Constituents In Grain-Refined Pd-Cu-Ga Dental Alloys, William A. Brantley, Zhuo Cai, John C. Mitchell, Stanley G. Vermilyea

Cells and Materials

Grain-refined Pd-Cu-Ga dental alloys solidify with a lamellar microstructural constituent that affects a variety of clinically relevant properties. While formation of this constituent has been attributed to eutectic solidification, an alternative mechanism of discontinuous precipitation has been proposed. Using a representative grain-refined Pd-Cu-Ga dental alloy, casting procedures involving two different rates of solidification were used: (a) A standard thin-walled coping configuration for a metal-ceramic restoration was cast into a room temperature mold, followed by rapid quenching into an ice-water mixture. (b) A thin plate specimen was cast into a standard elevated-temperature mold, with the same subsequent rapid quenching procedure. Neither ...


Peripheral Nerve Regeneration And Functional Nerve Recovery After Reconstruction With A Thin-Walled Biodegradable Poly(Dl-Lactide-Ε-Caprolactone) Nerve Guide, M. F. Meek, W. F. A. Den Dunnen, H. L. Bartels, A. J. Pennings, P. H. Robinson, J. M. Schakenraad Jan 1997

Peripheral Nerve Regeneration And Functional Nerve Recovery After Reconstruction With A Thin-Walled Biodegradable Poly(Dl-Lactide-Ε-Caprolactone) Nerve Guide, M. F. Meek, W. F. A. Den Dunnen, H. L. Bartels, A. J. Pennings, P. H. Robinson, J. M. Schakenraad

Cells and Materials

The aim of this study was to evaluate functional nerve recovery after reconstruction of a 1 em gap in the sciatic nerve of the rat, with a thin-walled biodegradable poly(DLLA-ε-CL) nerve guide. To evaluate both motor and sensory nerve recovery, walking track analysis and electrostimulation tests were carried out after implantation periods ranging from 3 to 26 weeks post-operatively. The first signs of functional nerve recovery could already be observed after 5 weeks. From the histological analysis, it could be concluded that most of the thin-walled nerve guides had collapsed. Despite collapsing, functional nerve recovery was relatively good after ...


A Quantitative Method Of Measuring Cell-Substrate Adhesion Areas, R. G. Richards, G. Rh Owen, B. A. Rahn, I. Ap Gwynn Jan 1997

A Quantitative Method Of Measuring Cell-Substrate Adhesion Areas, R. G. Richards, G. Rh Owen, B. A. Rahn, I. Ap Gwynn

Cells and Materials

Variability in measurements of the 'cell adhesion strength' of fibroblasts to substrates using mechanical disruption techniques causes difficulty in determining precisely the position, in the cytoskeleton-focal adhesion-matrix -substrate interface, where failure has occurred. In the present study, a quantitative in vitro procedure for measuring the total area and percentage of fibroblast adhesion to biomaterials, using the scanning electron microscope (SEM), is described. The amount of adhesion ofL929 and Balb/c3T3 fibroblasts to discs of stainless steel, commercially pure titanium, and polyethylene terepthalate (Thermanox) was quantified. Cells were fixed, stained with heavy metals, dehydrated and embedded in resin. The resin blocks ...


Fractals, Surface Roughness, And Fracture Toughness Of Dental Composite And Unfilled Resin Fracture Surfaces, James L. Drummond Jan 1997

Fractals, Surface Roughness, And Fracture Toughness Of Dental Composite And Unfilled Resin Fracture Surfaces, James L. Drummond

Cells and Materials

The intent of this project was to evaluate whether or not there exists a correlation between fractal dimension, surface roughness, and fracture toughness of an unfilled resin and a filled composite. The fracture surfaces of the unfilled resin and the filled composite were examined using atomic force microscopy (AFM) and a surface roughness measuring device. The specimens examined were aged in distilled water or air at 37°C for up to 12 months. Line scans of 1.4 µm for the atomic force microscope and 0.25 mm for the surface analyzer across the fracture surface were conducted on ...


Corrosion Of Metal Hip Arthroplasties And Its Possible Role In Loosening, H. K. Koerten, J. J. A. M. Van Raay, J. J. M. Onderwater, F. P. Bernoski, P. M. Rozing Jan 1997

Corrosion Of Metal Hip Arthroplasties And Its Possible Role In Loosening, H. K. Koerten, J. J. A. M. Van Raay, J. J. M. Onderwater, F. P. Bernoski, P. M. Rozing

Cells and Materials

Tissue removed with human hip arthroplasties during revision surgery of 45 patients was evaluated by transmission electron microscopy and X -ray microanalysis (XRMA). The results show that microscopic and submicroscopic particles are abundantly present in the tissue at the tissue/implant interface. XRMA of individual particles shows that the chemical composition of a portion of the particles was in agreement with that of the retrieved implants. Regularly, particulates with a dissimilar chemical composition were found. Sometimes, these particles could be recognized as filler particles of the cements used. Other particles could partly or completely be composed of the chemical elements ...


Detachment Of Human Endothelial Cells Under Flow From Wettability Gradient Surfaces With Different Functional Groups, T. G. Ruardy, H. E. Moorlag, J. M. Schakenraad, H. C. Van Der Mei, H. J. Busscher Jan 1997

Detachment Of Human Endothelial Cells Under Flow From Wettability Gradient Surfaces With Different Functional Groups, T. G. Ruardy, H. E. Moorlag, J. M. Schakenraad, H. C. Van Der Mei, H. J. Busscher

Cells and Materials

In this study, the position bound adhesion, spreading and detachment under flow of human umbilical cord endothelial cells (HUVEC) was studied on a dichlorodimethylsilane (DDS), dimethylocta-decylchlorosilane (DOCS) and tridecafluor-1,1,2,2-tetrahydrooctyl-1-dimethylchlorosilane (TFCS) wettability gradient on glass. Gradient surfaces were prepared by the diffusion method and characterized by the Wilhelmy plate technique for their wettability and by X-ray photoelectron spectroscopy (XPS) for their chemical composition. Quantitative analysis of the cellular response on the wettability gradient surfaces showed that the position bound cellular response was influenced by wettability for each type of gradient in a different way. On DDS-wettability gradients, cells ...


Macrophage Response To Polymethylmethacrylate Particles, Stephen M. Horowtiz Jan 1997

Macrophage Response To Polymethylmethacrylate Particles, Stephen M. Horowtiz

Cells and Materials

This paper reviews studies performed by this laboratory involving the macrophage response to implant particles. Through the development of a tissue culture model, we have studied the events which occur following macrophage phagocytosis of bone cement particles, the released mediators and cell interactions which may ultimately lead to bone resorption, and the inhibition of this process with the use of pharmaceutical agents. This is divided into the following sections: Histologic response of macrophages to cement particles I toxicity I and mediator release, the effects of particle size and composition on mediator release by macrophages, macrophage I osteoblast interactions, macrophage I ...


Image Analysis Of Primary Bone-Derived Cells On Different Polystyrene Surfaces, R. M. Shelton, G. Landini Jan 1997

Image Analysis Of Primary Bone-Derived Cells On Different Polystyrene Surfaces, R. M. Shelton, G. Landini

Cells and Materials

The aim of the present study was to examine whether two different cell populations could be discerned using image analysis of a variety of morphological parameters on bacteriological and tissue culture polystyrene surfaces. Rat periosteal and osteoblast cultures were established on both polystyrene petri dishes and examined using phase contrast microscopy after one and two weeks before capturing digital images which were stored on a personal computer. The digital images were processed to identify the cell margins or perimeter, from which seven different morphological parameters were calculated using a program developed (by GL) for both the cell populations on the ...


Beta-Tricalcium Phosphate Resorption By Monocytes In Biphasic Calcium Phosphate: An In Vitro Study, Wolf Bohne, Jean A. Pouëzat, Dorothea Pouëzat, Guy Daculsi Jan 1997

Beta-Tricalcium Phosphate Resorption By Monocytes In Biphasic Calcium Phosphate: An In Vitro Study, Wolf Bohne, Jean A. Pouëzat, Dorothea Pouëzat, Guy Daculsi

Cells and Materials

A macroporous biphasic calcium phosphate (BCP) of 60.7% carbonated dense non-porous hydroxyapatite (HA)/39.3% dense microporous ß-tricalcium phosphate (ß-TCP) was immersed during 15 days in a supplemented a-MEM (minimal essential medium) solution with and without dog bone marrow cells obtained by punction. The aim of the study was to demonstrate the time-related changes in the BCP fractions by means of X -ray diffraction, infrared spectroscopy and scanning electron microscopy, and to investigate the cell populations. The HA/ß-TCP ratios varied according to immersion duration and cell presence. If any, there was a slight preponderance of ...


Laser Profilometry Of Polymeric Materials, Eduard A. Kulik, Patrick Calahan Jan 1997

Laser Profilometry Of Polymeric Materials, Eduard A. Kulik, Patrick Calahan

Cells and Materials

Unlike the mechanical stylus profilometer, the laser profilometer does not damage the surface of soft materials. However, the accuracy of autofocusing of the laser profilometer is not always sensitive enough to discriminate the material/air interface from subsurface structures of semitransparent polymers. In the present study over ten polymeric surfaces were gold coated in order to investigate the effect of gold coating on the readings of a laser profilometer. Surface profiles of some polymeric materials became much smoother even if a very thing gold coating was applied to increase the reflection from the surface. It was concluded that a thin ...


Heat-Treatment Behavior Of High-Palladium Dental Alloys, Qiang Wu, William A. Brantley, John C. Mitchell, Stanley G. Vermilyea, Jianzhong Xiao, Wenhua Guo Jan 1997

Heat-Treatment Behavior Of High-Palladium Dental Alloys, Qiang Wu, William A. Brantley, John C. Mitchell, Stanley G. Vermilyea, Jianzhong Xiao, Wenhua Guo

Cells and Materials

Four high-palladium dental alloys were cast, quenched following solidification, and heat treated at temperatures ranging from 200° to 1,800°F. The Vickers hardness of each alloy was measured, and microstructural changes were studied by scanning electron microscopy (SEM). Phase transformations were investigated by thermomechanical analysis (TMA). Heat treatment at 1,600° and 1,800°F significantly decreased the hardness of one Pd-Cu-Ga alloy, compared to the as-cast condition, as did heat treatment at 1,800°F for the other Pd-Cu-Ga alloy and one Pd-Ga alloy, and yielded fine-grained microstructures of the palladium solid solution. There were generally no significant ...


Biofilms In Dental Unit Waterlines: Ultrastructural And Cytochemical Analysis, J. Barbeau, C. Avezard, E. Faucher, S. Zalzal, A. P. Prévost Jan 1997

Biofilms In Dental Unit Waterlines: Ultrastructural And Cytochemical Analysis, J. Barbeau, C. Avezard, E. Faucher, S. Zalzal, A. P. Prévost

Cells and Materials

Dental unit waterlines are heavily colonized by bacteria which contaminate the water used to perform intra-oral, and sometimes invasive, procedures. There is little information on the nature of the biofilm colonizing the flexible plastic tubing used to supply water to the different handpieces. We have therefore undertaken quantitative microbial analysis and ultrastructural studies of these biofilms by direct counting with the epifluorescent filter technique and by transmission and scanning electron microscopy after staining with ruthenium red and periodic acid-thiosemicarbazide-silver proteinate to visualize the composition and the distribution of exopolysaccharides and intracellular polysaccharides. The biofilm was revealed as a non-uniform structure ...