bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of bioactive ceramic dissolution on the mechanism of bone mineralization and guided tissue growth in vitro
Authors: El‐Ghannam A. , Ning C. Q. 
Published: November 2005

AbstractA major objective of this research work was to evaluate the effect of bone cells on the dissolution‐precipitation reaction in vitro. Rat bone marrow stem cells were seeded on silica‐calcium phosphate nano composite (SCPC) with different chemical compositions and crystalline structures. Measurements of the Ca, P, Si, and Na concentrations in the tissue culture media using inductively coupled plasma indicated that bone marrow stem cells attached to the surface of SCPC did not affect the dissolution behavior of the material. However, bone marrow stem cells interfered with the back precipitation reaction and inhibited the formation of a calcium phosphate (Ca‐P) layer on the material surface. Scanning electron microsope‐energy‐dispersive X‐ray analyses showed that, in the absence of cells, a Ca‐P layer formed on the material surface because of the dissolution‐precipitation reaction. Bone cells attached to SCPC that contains high silica content absorbed significantly higher concentrations of medium Ca than cells attached to SCPC that contains low silica content. In conjunction with the absorption of high Ca concentration, attached bone marrow stem cells produced calcified nodules and mineralized extracellular matrix, indicating osteoblastic differentiation. Results of the study strongly suggest that the mechanism of bone mineralization at the interface with bioactive ceramics is mainly cell mediated and is enhanced by the absorption of critical concentrations of dissolved Ca and P. The silicon‐rich phase also provided a guided cell adhesion and tissue growth in vitro. The enhanced bioactivity reactions and strong stimulatory effect on bone cell function are attributed to the modified crystalline structure of the SCPC material. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Enhancing surface free energy and hydrophilicity through chemical modification of microstructured titanium implant surfaces
Authors: Rupp F. , Scheideler L. , Olshanska N. , de Wild M. , Wieland M. , Geis‐Gerstorfer J. 
Published: November 2005

AbstractRoughness‐induced hydrophobicity, well‐known from natural plant surfaces and intensively studied toward superhydrophobic surfaces, has currently been identified on microstructured titanium implant surfaces. Studies indicate that microstructuring by sandblasting and acid etching (SLA) enhances the osteogenic properties of titanium. The undesired initial hydrophobicity, however, presumably decelerates primary interactions with the aqueous biosystem. To improve the initial wettability and to retain SLA microstructure, a novel surface modification was tested. This modification differs from SLA by its preparation after acid etching, which was done under protective gas conditions following liquid instead of dry storage. We hypothesized that this modification should have increased wettability due to the prevention of contaminations that occurs during air contact. The main outcome of dynamic wettability measurements was that the novel modification shows increased surface free energy (SFE) and increased hydrophilicity with initial water contact angles of 0° compared to 139.9° for SLA. This hydrophilization was kept even after any drying. Reduced hydrocarbon contaminations were identified to play a possible role in altered surface thermodynamics. Such surfaces aim to retain the hydrophilicity and natural high surface energy of the Ti dioxide surface until surgical implants' insertion and are compared in this in vitro study with structural surface variants of titanium to compare roughness and chemically induced wettability. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Bone response to 3D periodic hydroxyapatite scaffolds with and without tailored microporosity to deliver bone morphogenetic protein 2
Authors: Dellinger Jennifer G. , Eurell Jo Ann C. , Jamison Russell D. 
Published: November 2005

AbstractThree types of model hydroxyapatite (HA) scaffolds were implanted in the metacarpal and metatarsal bones of goats. Scaffolds, consisting of a latticed pattern of rods, were fabricated with a solid freeform fabrication (SFF) technique. All scaffolds contained macropores; some were also fabricated with micropores (5.2 ± 2.0 μm). Recombinant human bone morphogenetic protein‐2 (rhBMP‐2) was added to some microporous scaffolds. rhBMP‐2 caused increased percent filled with bone tissue compared to microporous scaffolds without rhBMP‐2. Lamellar bone in the scaffolds was aligned perpendicular to the long axis of the bone near the junctions of the rods that make up the scaffold but was more random away from the junctions of rods. Microporous scaffolds stained beneath areas of contact with new bone. This staining might indicate either extracellular matrix (ECM) in the rods, byproducts of ECM production, or reaction of cellular products with the scaffold. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Plasma‐immersion ion‐implanted nitinol surface with depressed nickel concentration for implants in blood
Authors: Maitz Manfred F. , Shevchenko Natalia 
Published: November 2005

AbstractIon implantation into nitinol had been shown previously to decrease the surface nickel concentration of this alloy and produce a titanium oxide layer. Nothing is known yet about the blood compatibility of this surface and the suitability for implants in the blood vessels, like vascular stents. Nickel depletion of superelastic nitinol was obtained by oxygen or helium plasma‐immersion ion implantation. The latter leads to the formation of a nickel‐poor titanium‐oxide surface with a nanoporous structure, which was used for comparison. Fibrinogen adsorption and conformation changes, blood platelet adhesion, and contact activation of the blood clotting cascade have been checked as in vitro parameters of blood compatibility; metabolic activity and release of cytokines IL‐6 and IL‐8 from cultured endothelial cells on these surfaces give information about the reaction of the blood vessel wall. The oxygen‐ion‐implanted nitinol surface adsorbed less fibrinogen on its surface and activated the contact system less than the untreated nitinol surface, but conformation changes of fibrinogen were higher on the oxygen‐implanted nitinol. No difference between initial and oxygen‐implanted nitinol was found for the platelet adherence, endothelial cell activity, or cytokine release. The nanoporous, helium‐implanted nitinol behaved worse than the initial one in most aspects. Oxygen‐ion implantation is seen as a useful method to decrease the nickel concentration in the surface of nitinol for cardiovascular applications. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
A long‐term in vitro biocompatibility study of a biodegradable polyurethane and its degradation products
Authors: van Minnen B. , Stegenga B. , van Leeuwen M. B. M. , van Kooten T. G. , Bos R. R. M. 
Published: November 2005

AbstractThe biological safety of degradation products from degradable biomaterials is very important. In this study a new method is proposed to test the cytotoxicity of these degradation products with the aim to save time, laboratory animals, and research funds. A biodegradable polyurethane (PU) foam was subjected to this test method. The PU had soft segments of DL‐lactide/ϵ‐caprolactone and hard segments synthesized from butanediol and 1,4‐butanediiosocyanate. Copolymer foams without urethane segments, consisting of DL‐lactide/ϵ‐caprolactone, were tested as well. Accumulated degradation products were collected by degrading the foams in distilled water at 60°C up to 52 weeks. Cell‐culture medium was prepared from powder medium with this water. In different tests the cytotoxicity of this medium was established. The first signs of cytotoxicity were observed after 3–5 weeks of degradation. This accounts for both materials and reestablishes the good short‐term biocompatibility of these materials. The PU showed more toxicity toward the end stages of degradation in comparison with the copolymer. This is probably related to the accumulation of degradation products of the urethane segments. In the in vivo situation the degradation of the PU and the metabolism and excretion of degradation products may differ. Therefore, long‐term in vivo studies will have to establish whether these in vitro results are representative for the in vivo behavior of the degrading PU. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Testing the utility of rationally engineered recombinant collagen‐like proteins for applications in tissue engineering
Authors: Ito Hidetoshi , Steplewski Andrzej , Alabyeva Tatiana , Fertala Andrzej 
Published: November 2005

AbstractCollagens are attractive proteins as materials for tissue engineering. Over the last decade, significant progress has been made in developing technologies for large‐scale production of native‐like human recombinant collagens. Yet, the rational design of customized collagen‐like proteins for smart biomaterials to enhance the quality of engineered tissues has not been explored. We mapped the D4 domain of human collagen II as most critical for supporting migration of chondrocytes and used this information to genetically engineer a collagen‐like protein consisting of tandem repeats of the D4 domain (mD4 collagen). This novel collagen has been utilized to fabricate a scaffold for support of chondrocytes. We determined superior qualities of cartilaginous constructs created by chondrocytes cultured in scaffolds containing the mD4 collagen in comparison to those formed by chondrocytes cultured in bare scaffolds or those coated with wild‐type collagen II. Our results are a first attempt to rationally engineer collagen‐like proteins with characteristics tailored for specific needs of cartilage engineering and provide a basis for rational engineering of similar proteins for a variety of biomedical applications. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Effect of cast molded rifampicin/silicone on staphylococcus epidermidis biofilm formation
Authors: Liang Xuemei , Wang Anfeng , Cao Ting , Tang Haiying , McAllister James P. , Salley Steven O. , Ng K. Y. Simon 
Published: November 2005

AbstractInfection is one of the most common catheter‐related complications, especially in shunt systems used to treat hydrocephalus. Staphylococcus epidermidis is directly related to biomaterial infections owing to its ability to form a biofilm on implanted materials. In this study, scanning electron microscopy (SEM) and atomic force microscopy (AFM) were employed to investigate the effect of the antibiotic rifampicin on the colonization and growth of S. epidermidis 35984 on the surface of silicone. A cast molding method was used to load rifampicin into the silicone precursor before it was cured. Bacteria with a diameter of 800–1000 nm and height of 200–500 nm were found to be embedded in the biofilm. Compact multilayer biofilm structures were found on silicone surfaces upon incubation for 4 and 24 h. On the other hand, sparser biofilm structures were observed on rifampicin‐loaded surfaces after incubation for the same duration. Deformation of bacteria was observed by AFM. Moreover, different bacterial colony structures on the surfaces of silicone and rifampicin‐loaded silicone were observed by AFM and SEM. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Biological effects of calcium sulfate as a bone graft substitute in ovine metaphyseal defects
Authors: Peters Christopher L. , Hines Jerod L. , Bachus Kent N. , Craig Marcis A. , Bloebaum Roy D. 
Published: November 2005

AbstractCalcium sulfate has been used as a bone graft substitute in many fields, from dentistry to orthopedics. However, the results of many studies have yielded inconclusive results. In the present study, a sheep model was used with tibial and femoral metaphyseal defects to determine whether calcium sulfate was as effective as autograft and allograft in promoting new bone formation in a critical size defect. Medical‐grade calcium sulfate pellets, autograft bone, allograft bone, or nothing was used to fill the metaphyseal defects. The sheep were allowed to heal for 12 weeks. Sagittal sections from the bones were analyzed with high‐resolution contact radiographs, backscattered electron microscopy, and light microscopy. The volume fractions of bone within the defect perimeter were determined, and the histologic quality of the bone was observed. The volume fraction of new bone in the autograft, calcium sulfate, and allograft were not statistically different, but all were significantly different than the untreated control. The majority of the calcium sulfate had been resorbed at 12 weeks, and the histologic quality of the bone appeared similar to the autograft‐treated bone. Calcium sulfate appears to be a useful biocompatible bone graft substitute that yields results similar to autograft bone in sheep metaphyseal defects. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
In vivo biocompatibility of bacterial cellulose
Authors: Helenius Gisela , Bäckdahl Henrik , Bodin Aase , Nannmark Ulf , Gatenholm Paul , Risberg Bo 
Published: November 2005

AbstractThe biocompatibility of a scaffold for tissue engineered constructs is essential for the outcome. Bacterial cellulose (BC) consists of completely pure cellulose nanofibrils synthesized by Acetobacter xylinum. BC has high mechanical strength and can be shaped into three‐dimensional structures. Cellulose‐based materials induce negligible foreign body and inflammatory responses and are considered as biocompatible. The in vivo biocompatibility of BC has never been evaluated systematically. Thus, in the development of tissue engineered constructs with a BC scaffold, it is necessary to evaluate the in vivo biocompatibility. BC was implanted subcutaneously in rats for 1, 4, and 12 weeks. The implants were evaluated in aspects of chronic inflammation, foreign body responses, cell ingrowth, and angiogenesis, using histology, immunohistochemistry, and electron microscopy. There were no macroscopic signs of inflammation around the implants. There were no microscopic signs of inflammation either (i.e., a high number of small cells around the implants or the blood vessels). No fibrotic capsule or giant cells were present. Fibroblasts infiltrated BC, which was well integrated into the host tissue, and did not elicit any chronic inflammatory reactions. The biocompatibility of BC is good and the material has potential to be used as a scaffold in tissue engineering. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Improvement in hydrophilicity of PHBV films by plasma treatment
Authors: Wang Yingjun , Lu Ling , Zheng Yudong , Chen Xiaofeng 
Published: November 2005

AbstractPoly(3‐hydroxybutyrate‐co‐hydroxyvalerate) (PHBV) films were prepared by the solvent cast method. Oxygen and nitrogen plasma treatment were used to improve the hydrophilicity of the surface of PHBV films. The surface properties were characterized by contact angle measurement and X‐ray photoelectron spectroscopy (XPS). The water contact angle of PHBV films decreased after plasma treatment, which suggested that the surfaces became more hydrophilic. The effects of exposure time, plasma generating power, and chamber pressure on water contact angle were investigated. Although the decrease of contact angle with both plasma treatments was similar, the change of PHBV surface structure was different. XPS analysis showed that the oxygen content and the ratio of O/C increased markedly after oxygen plasma treatment, while after nitrogen plasma treatment, the surface was enriched with nitrogen atoms. Furthermore, it was found that CO and CC bonds were broken with both plasma treatment, while different new bonds were formed, that is, COOH (for oxygen plasma), and CN, CN, and amide bonds (for nitrogen plasma) have been generated after plasma irradiation. Dog bone marrow stromal cell culture studies showed that cells grew better on the plasma treated surface. These results demonstrate potentiality of this method for grafting useful component in future tissue‐engineering applications. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Strontium‐containing hydroxyapatite (Sr‐HA) bioactive cement for primary hip replacement: An in vivo study
Authors: Ni G. X. , Lu W. W. , Chiu K. Y. , Li Z. Y. , Fong D. Y. T. , Luk K. D. K. 
Published: November 2005

AbstractThe purpose of this study was to evaluate the strontium‐containing hydroxyapatite (Sr‐HA) cement in primary hip replacement, using a rabbit model, and to investigate the histological findings at the cement–implant and bone–cement interfaces under weight‐bearing conditions. Unilateral hip replacement was performed with Sr‐HA cement or polymethylmethacrylate (PMMA) cement in rabbits and observations were made after 6 months. Good fixation between the Sr‐HA cement and implant was observed. Osseointegration of the Sr‐HA cement with cancellous bone was widespread. Many multinucleus cells covered the surface of the cement, and resorbed the superficial layer of the cement. By scanning electron microscopy (SEM) and energy‐dispersive X‐ray (EDX) analysis, high calcium and phosphorus levels were detected at the interface with a thickness of about 10 μm. Intimate contact was also observed between the Sr‐HA cement and cortical bone without fibrous layer intervening. The overall affinity index of bone on Sr‐HA cement was (85.06 ± 5.40)%, which is significantly higher than that on PMMA cement (2.77%± 0.49%). On the contrary, a fibrous layer was consistently observed between PMMA cement and bone, and PMMA cement evoked an inflammatory response and foreign body reaction in the surrounding bony tissues. Results suggested good bioactivity and bone‐bonding ability of the Sr‐HA cement under weight‐bearing conditions. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Fabrication of polycaprolactone scaffolds using a sacrificial compression‐molding process
Authors: Yao Donggang , Smith Aaron , Nagarajan Pratapkumar , Vasquez Adrian , Dang Loan , Chaudhry G. Rasul 
Published: November 2005

AbstractA method of compression‐molding fine‐powder blends of polycaprolactone (PCL) and poly(ethylene oxide) (PEO) and subsequently dissolving the PEO phase was investigated to prepare porous PCL scaffolds. Different mixing ratios of the two polymers from 20 to 70% PCL were used to study the effect of the mixing ratio on the morphology formation of the scaffold. The mixing ratio was found to play an important role in affecting the porosity of the scaffold and the size of pores. Murine embryonic stem cell derived osteogenic cells were utilized to test the suitability of these scaffolds in tissue engineering applications. The seeded cells were able to colonize and grow in these scaffolds. Based on the overall consideration of morphology, mechanical performance, and ability for cell attachment and proliferation, the scaffolds with approximately 30–40% PCL appear to be an appropriate choice for tissue engineering. These findings suggest that sacrificial compression‐molding of PCL–PEO powder blends can be used in the generation of biocompatible scaffolds with controllable porosity and pore size and may be used for in vitro tissue engineering applications. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Role of fluid dynamics on the healing of an in vivo tissue engineered vascular graft
Authors: Lyman Donald J. , Stewart Sandy F.C. , Murray‐Wijelath Jacqueline , Wijelath Errol 
Published: November 2005

AbstractA polyester (PET) reinforced fibrin‐FN‐VEGF‐TGFβ vascular graft, formed by a four‐step preclotting technique of a porous PET arterial graft, shows the overlapping inflammation, proliferation, and remodeling steps of normal wound healing when implanted in the descending thoracic aorta (DTA) position in the dog, forming a surface layer of endothelial cells. While the DTA grafts readily healed (i.e., endothelialized), similar grafts implanted in the carotid–femoral artery position did not fully heal. Since the initial phases of healing were shown to be dependent upon the transport of blood‐borne constituents to the graft surface, the extent of healing appears to be dependent on the fluid dynamics present in the artery–graft–artery construct. The length of the noncompliant graft, the construction of the anastomoses, bends in the construct, graft diameter, and graft compliance can affect the fluid dynamics in the implant, and thus the healing of the graft. This has clinical relevance for the testing and development of new vascular graft materials. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Nanoindentation of dental composites
Authors: Drummond James L. 
Published: November 2005

AbstractThe intent of this project was to evaluate the elastic modulus and hardness of four composites with different fillers, a microfill, a hybrid, a dental resin cement, and a fiber filler, using nanoindentation. An indentation load of 0.001 N was used and 100 indents per specimen were taken. The elastic modulus measured for the Choice composite was 30.2–30.3 GPa, 15.9–16.0 GPa for Micronew, 24.6–27.1 GPa for Renew, and 36.4–47.1 GPa for Restolux. The statistical analysis indicated a significant difference in the elastic modulus for all four composites. Micronew had the lowest hardness (1.2–1.3 GPa) followed by Renew (1.6–1.8 GPa), Choice (2.6–2.8 GPa), and Restolux (2.7–4.0 GPa). The statistical analysis indicated a significant difference between Choice and Restolux from Micronew and Renew, with Renew and Micronew not being significantly different from each other. Nanoindentation of dental composites, using a 10 × 10 matrix of indentations, resulted in a wide range of measured values for the elastic modulus and hardness because of the size of the filler particle, the location of the indenter within the filler particle, the composition of the filler particles, and the location of the indenter within the filler/resin matrix. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
A novel method to obtain microtensile specimens minimizing cut flaws
Authors: Sadek Fernanda Tranchesi , Monticelli Francesca , Muench Antonio , Ferrari Marco , Cardoso Paulo Eduardo Capel 
Published: November 2005

AbstractCutting procedures conventionally used for microtensile specimens' preparation induce mechanical stress and attrition, leading to cracks in dental structure. Enamel is mainly affected due to its high module of elasticity and brittleness. As an alternative to the conventional diamond saw, a diamond wire was used for cutting. The two techniques were compared in efficacy in the preparation of two different sample shapes. Forty human molars, flattened in dentin or enamel, were used for sample preparation. After bonding procedures, resin block was built incrementally. Half of the teeth were cut using a diamond disc and the other half using a diamond wire, obtaining slabs and stick‐shaped specimens. Slabs were then shaped to obtain hourglass samples. Five samples from each subgroup were randomly selected for Scanning electron microscopy (SEM) analysis. Remaining samples underwent microtensile test and the results were analyzed, including/excluding premature failures (pf), with three‐way ANOVA and Tukey test, performed separately, by substrate. On dentin, only the exclusion of pf showed a significant higher bond strength values than when pf were included (p < 0.05); however, on enamel, all factors (equipment, shape and including/excluding pf) had a significant effect on bond strength (p<0.05). The most remarkable finding from SEM was the incidence of specimens' cracks and defects when diamond blade was used. Scratches and cracks in the hourglass‐shaped specimens were also detected. In both cases, enamel was more affected than dentin. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006