摘要:

AbstractComplications arising in the application of polyethylene catheters in surgery may be reduced by their surface hydrophilization. This study describes a combination of chemical transformation and coating with a hydrophilic gel. Modified catheters were tolerated well by the patients and in contrast with the original catheters, they did not lead to the formation of thrombi or phlebitis.

ISSN:0021-9304    

DOI:10.1002/jbm.820100102

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractThe present study was conducted in order to understand the microstructural characteristics in dental amalgam which consists of both spherical and irregular Ag3Sn alloy particles with gold substituted in varying amounts for silver (0, 9, and 15%). Spherical alloy particles were used as obtained from Western Gold and Platinum and irregular alloy particles were prepared in the laboratory and then employed in the present study. The amalgam was prepared from the alloy particles by the trituration and condensation method. The polished and etched samples were studied using the techniques of X‐ray diffraction, optical metallography, scanning electron microscopy, and X‐ray energy dispersive spectroscopy. The microstructure in both types amalgam studied after two weeks of preparation contains γ (unreacted Ag3Sn particles), γ1(Ag2Hg3), and γ2(Sn7–8Hg) phases in pure Ag3Sn‐amalgam and γ, γ1, and (Au–Sn) phases in gold‐containing amalgam. The (Au–Sn) phase existed in the form of rings surrounding the γ grains and acted as a barrier for mercury diffusion

ISSN:0021-9304    

DOI:10.1002/jbm.820100103

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

ISSN:0021-9304    

DOI:10.1002/jbm.820100104

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractThis work pertains to the development of high strength elastomers potentially useful as nonthrombogenic cardiovascular prostheses. Triblock copolymers of the styrene–butadiene–styrene type have been subjected to surface hydroxylation which provide reactive sites at the surface for the subsequent coupling of heparin while retaining the unique mechanical properties of the SBS copolymers. Curves of hydroxyl content versus the copolymer film thickness demonstrate the effect of swelling in the surface region on the product distribution and on the time dependence of the hydroxylation process. In addition, the effect of time, temperature, and the composition of the reaction bath on the diffusion/reaction process is shown. Finally, the general applicability of this surface modification scheme to the development of biomaterials is discus

ISSN:0021-9304    

DOI:10.1002/jbm.820100105

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractSurgical replacement of the Achilles and patellar tendons using Dacron mesh silicone prostheses was performed in 15 mature beagle dogs. This part of the study includes clinical evaluation, gross inspection at autopsy of regrown tendons, and histological determination of biocompatibility of prosthetic implants.Functional continuity and integrity of prosthetic patellar tendons have been established by evaluating the biologic–prosthetic interface and the mechanical properties of regrown tendon tissue around and through the Dacron silicone replacements. Results of prosthetic Achilles tendons were less satisfactory because of difficulties in suturing to a muscle and its fascia. Although the prosthetic tendon did not regrow through the tube, it provided a structure for regrowth around it. The regrown tendons became nearly ten times the normal crosssectional area after three to four months and decreased to two to three times after 13 months.Histological studies indicate that in the absence of infection, the Dacron mesh silicone tendon was well tolerated for periods up to 13 months. Overall results are encouraging and warrant further investigation although the regenerative capacity of human patellar and Achilles tendons is unknow

ISSN:0021-9304    

DOI:10.1002/jbm.820100106

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractSome of the mechanical properties of regrown canine tendons are compared to those of normal tendons of young and mature animals. Patellar and Achilles tendons from 12 beagle dogs were removed and studied with their bone origin and insertions. Mechanical tests were performed within 24 hr and test conditions simulated the physiological function of the tendonin vivoat room temperature. Specimens were soaked in Ringers solution and mounted in an Instron testing machine with load deflection curves plotted automatically. The parameters used for analysis were load extension, stress relaxation, elastic limit, and strain rate dependence.The regrown tendons in young animals appeared to quickly adjust in dimension and structure so that their properties were not significantly different from those of normal tendons on a load extension basis.The normal tendons were stiffer than regrown ones but the modulus of elasticity increased with age. The Achilles were stiffer than patellar tendons. Cyclic loading with 25 kg did not affect reconstructed tendon models, although some increase in stiffness was noted. The elastic modulus decreased with an increase in ambient temperature and increasing strain rate.

ISSN:0021-9304    

DOI:10.1002/jbm.820100107

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractAn investigation was made of the influence of application techniques on the microstructure and properties of an acrylic tooth restorative. Mixtures of acrylic powder and monomer (“Sevriton Simplified”) were applied by the brush technique of Nealon (J. Prosth. Dent.,2, 513, 1952) and by two bulk flow techniques. While similar porosities (about 4%) were observed, the brush technique resulted in a greater quantity of grains from the acrylic powder. Despite this, there was little difference in values of compression modulus, compressive yield stress, and diametral compressive strength.The mechanical strength of the materials studied was less than one‐half that of high molecular weight poly (methyl methacrylate) (PMMA). Crack propagation studies established that the interface between the grains and matrix was not a source of weakness. However, as the matrix was crosslinked this could not be checked by solution methods of polymer characteriz

ISSN:0021-9304    

DOI:10.1002/jbm.820100108

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractThe chromium content of hair has been studied by neutron activation analysis of samples from 62 patients following a Charnley unilateral or bilateral hip arthroplasty by an artificial joint of stainless steel against polyethylene, inserted three to five years previously. The patients lived in the North Wales area of the British Isles. Hair chromium content was also studied in 51 control subjects of similar age to that of the patients, from the same geographical area and often from the patients' own households.Chromium content was recorded as parts per million (ppm) of hair weighed and analyzed in the state received, without preliminary ashing or chemical “washing” of the samples in the laboratory. Fifty of the 51 control subjects showed less than 2 ppm chromium in hair; one showed 2–5 ppm; none showed more than 5 ppm. Fifty‐nine of the 62 patients showed less than 2 ppm chromium in hair; three showed 2–5 ppm; none showed more than 5 ppm.Attention is drawn to certain practical aspects when collecting hair samples for chromium analysis. The use and validity of hair sampling as one method of screening for systemic chromium accumulation following implant surgery is discussed. The method may be a useful adjunct to monitoring of chromium levels in blood samples. In this preliminary study, hair sampling has given no evidence of any major risk of systemic chromium accumulation in patients using a Charnley arthroplasty for periods of up to five years; no conclusion can be made concerning periods longer than this. The findings do not exclude systemic reactions of the hypersensitivity type, since this type of reaction could develop to only small amounts of

ISSN:0021-9304    

DOI:10.1002/jbm.820100109

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractUsing a well characterized series of styrene butadiene triblock copolymers a systematic study was carried out to determine the influence of casting solvent, used for film preparation, on the final mechanical properties. The results clearly indicate that in the range of styrene contents of 30–40 mol %, the modulus behavior is greatly affected as the solubility parameter of the casting solvent, δ, is varied. Specifically, the modulus increases as δ increases to the value of polystyrene. At lower or higher styrene content, the properties are influenced but to a much lesser degree. Other mechanical properties measured were yield stress and breaking stress. The ramifications of these data are discussed in light of preparing prosthetic material via solvent cast

ISSN:0021-9304    

DOI:10.1002/jbm.820100110

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractThe growth of cultured calf aortic smooth muscle cells on cardiovascular biomaterials was investigated, using native and oxidized polyacrylonitrile (orlon) fabrics, dacron velour, and Parylene‐C coated polypropylene microfabric as substrates. By light microscopic evaluation, surface cell coverage was most complete on microfabric, followed by native orlon, dacron velour, and oxidized orlon. Native orlon supported the greatest total cell growth, as determined by chemically extractable protein, followed by oxidized orlon, dacron velour, and the microfabric. The observed differences appear to be related to the pore size and fiber thickness of the different substrate

ISSN:0021-9304    

DOI:10.1002/jbm.820100111

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY