摘要:

AbstractThe effect of different treatments for preparing implant materials was examined by scanning electron microscopy and by contact angle measurements. The materials examined were Ti6Al4V alloy, Co‐Cr‐Mo alloy, Al2O3, and synthetic hydroxyapatite. Samples were prepared with solid or porous surfaces of these materials. These were detergent‐cleaned and then either autoclaved (steam sterilization), radiationsterilized, nitric acid‐etched, or plasmacleaned. The results of wettability studies indicated marked changes in surface energy corresponding to the different preparation methods, and differences in surface morphology were also observed. These differences could have significant consequences onin vivoimplant behaviour as mediated by tissue‐implant int

ISSN:0021-9304    

DOI:10.1002/jbm.820250902

出版商:John Wiley&Sons, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe tissue response to an implant may involve both physical and chemical factors. There is little reliable information on the effects of these parameters and the associated ionic release on the cell‐material interaction because the majority of studies have not fully characterized the implant material. In this work surface spectroscopy using ISS, ESCA, and SIMS was carried out on Ti6A14V, Co‐Cr‐Mo, Al2O3, and hydroxyapatite dental implant materials that had been subjected to six commonly used preparative procedures. The results showed that each procedure generated an individualistic composition for the outermost surface of each material. These differences could be significant in cellular and tissue response. Improved understanding of these factors requires defined and reproducible sur

ISSN:0021-9304    

DOI:10.1002/jbm.820250903

出版商:John Wiley&Sons, Inc.    

年代:1991

数据来源: WILEY

ISSN:0021-9304    

DOI:10.1002/jbm.820250904

出版商:John Wiley&Sons, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractSegmented poly(urethaneureas) with hydrophilic side chains were prepared from poly(tetramethylene oxide) (PTMO), 4,4′‐diphenylmethane diisocyanate (MDI), ethylene diamine (ED) and a diol with a long hydrophilic side chain comprised of an ethylene oxide‐propylene oxide copolymer. The end groups of the hydrophilic chains were either sodium sulfonate or methoxy groups. The state of microphase separation showed a small dependece on the fraction of long‐chain hydrophilic diol. Surface analysis by means of static underwater contact angle and dynamic contact angle measurements revealed that the graft chains were at the aqueous interface in the hydrated state. Anex vivoA‐V shunt experiment revealed that a more thrombogenic blood‐material response was correlated with an increase in the concentration of polymeric hydrophilic side chain incorporation. The polyurethane containing a long chain diol with methoxy end groups exhibited a higher level of thrombogenicity than the similar polymers possessing a sulfonate terminated

ISSN:0021-9304    

DOI:10.1002/jbm.820250905

出版商:John Wiley&Sons, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe inflammatory reaction to implanted biomaterials often compromises the clinical usefulness of implantable devices. Dexamethasone, an anti‐inflammatory agent, acts on macrophages to decrease production of inflammatory mediators, and on mast cells to prevent degranulation. Systemic administration of dexamethasone (dms) in rats decreases the tissue reaction to intraperitoneally implanted vinyl chloride‐acrylic copolymer capsules. Local release of even smaller amounts of dms from a polymeric substrate placed inside an acrylic copolymer capsule may control the tissue reaction while avoiding the undesirable side effects of systemic treatment. Such a system also allows investigation of the local effect of soluble molecules on tissuematerial interactions without altering the surface properties of the implant or adding the effect of a releasing material. In the present study, we investigated the effect of dms released from ethylene vinyl acetate (EVAc) rods placed in acrylic copolymer capsules and implanted in the peritoneal cavity of rats.In vitrothe release of dms from EVAc rods was quasilinear for 5 weeks. When implanted intraperitoneally into rats, polymer capsules containing EVAc/dms rods generated a tissue reaction that was significantly thinner and featured fewer fibroblast and collagen layers than that around capsules containing pure EVAc rods at all time points studied. The tissue reaction layer was also thinner than that previously described in rats treated systemically with dms. The trabeculae of implants with dms‐loaded EVAc rods contained significantly more intact mast cells is involved in the tissue reaction to intraperitoneal polymer imp

ISSN:0021-9304    

DOI:10.1002/jbm.820250906

出版商:John Wiley&Sons, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractThein vitrocytotoxicity of nine metal cations common in dental casting alloys was evaluated using Balb/c 3T3 fibroblasts and four toxicity parameters: total protein production,3H‐leucine incorporation,3H‐thymidine incorporation, and MTT‐formazan production. Concentrations causing 50% toxicity compared to controls (TC50's) and reversibility of these effects were determined. The range of potency of the metal cations was 2–3 orders of magnitude, with Cd2+showing the greatest potency and In3+showing the least. Potency did not correlate with atomic weight for these metals. For each metal cation, the TC50's of the various toxicity parameters were similar in most cases. However, several cations (Cu2+, Ga3+) showed greater potency with3H‐thymidine incorporation. Reversibility of the toxic effects was observed for all cations; the effects generally became irreversible at concentrations in the range of the TC50 value for each cation. Several stimulatory effects were seen. Small but statistically significant stimulations were observed after 24 h of metal exposure for Ag1+, Au4+, Cu2+, Ga3+, and Ni2+. Residual stimulations 24 h after removal of the metal cations were observed for Au4+, Cd2+, Ni2+, and Zn2+. Stimulations always occurred at concentrations below the TC50 concentrations. This study should be useful in evaluating the potential cytotoxic effects of metal cations released from dent

ISSN:0021-9304    

DOI:10.1002/jbm.820250907

出版商:John Wiley&Sons, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractA series of polymers, bisphenol A‐based poly(phosphoesters), were evaluated as degradable biomaterials. Degradation was observed for the four polymers studied under bothin vitroandin vivoconditions. The rate of degradation was affected by polymer side‐chain structure and correlated with the swelling behavior. The ethyl side‐chain polymers absorbed more water than their phenyl counterparts. Among the sterilization methods, UV irradiation followed by antibiotic treatment was the most suitable, as steam autoclave and ethylene oxide treatments altered the properties of several of the poly(phosphoesters). Tissue response to the poly(phosphoesters) in rabbits was characterized by minor encapsulation and slight or no lymphocyte, giant cell, or macrophage activity. No evidence of edema or necrosis was found. The elastic moduli of these materials varied from 488 MPa for poly(bisphenol A‐ethylphosphate) (BPA/EOP) to 627 MPa for the more rigid poly(bisphenol A‐phenylphosphonate) (BPA/PP). The ultimate strength, modulus, and energy to failure of BPA/PP were lower than those of similarly compression molded high‐molecular‐weight poly(L‐lact

ISSN:0021-9304    

DOI:10.1002/jbm.820250908

出版商:John Wiley&Sons, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractA new type of biocompatible copolymer comprising small fragments of heparin, (octa‐ to dodecasaccharides) copolymerized with a synthetic monomeric component, viz. acrylamide, has been prepared. The heparin fragments are produced by enzymatic or chemical means and are copolymerized, directly or after suitable derivatization, with acrylamide as the major polymerizable component. The polymeric material incorporates the heparin segments as pendant moieties such that their essential functional groups and structural features for specific binding with the selective serine protease coagulation factor inhibitor antithrombin III are preserved. An important feature of this copolymer is its biocompatibility which relates specifically to its antithrombotic and antithrombogenic activity derived from those of heparin fragments. The biological activity of heparin fragments and copolymers thereof are determined in terms of APTT and anti‐Xa activity, their antithrombotic potential being expressed as a ratio of anti‐Xa activity to APTT. The copolymers reported have biological activities similar to equivalent amounts of respective heparin fragments, and show higher antithrombotic activity compared to intact heparin or commercially available low‐molecular‐weight heparin (4,000

ISSN:0021-9304    

DOI:10.1002/jbm.820250909

出版商:John Wiley&Sons, Inc.    

年代:1991

数据来源: WILEY

ISSN:0021-9304    

DOI:10.1002/jbm.820250901

出版商:John Wiley&Sons, Inc.    

年代:1991

数据来源: WILEY