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  • Articles  (370)
  • Chemistry  (370)
  • Chemical Engineering
  • 1970-1974  (370)
  • Technology  (370)
  • 1
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 8 (1974), S. 115-126 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A standardized readily reproducible experimental model has been developed to assess the relative importance of the chemical and physical configuration of sutures as determinants of early infection in contaminated wounds. The chemical structure of the suture appeared to be the most important factor in the development of surgical infection. The incidence of infection in contaminated tissues containing either polypropylene sutures or nylon sutures was lower than the infection rate of tissues subjected to any other nonabsorbable suture. Among the absorbable sutures, polyglycolic acid (PGA) sutures evoked the least inflammatory response. The infection rate of contaminated tissues containing the PGA sutures was not significantly different from the incidence of infection of tissues subjected to the least reactive nonabsorbable sutures. The physical configuration of the suture played a relatively unimportant role in the development of early infection. The infection rate of contaminated tissues containing monofilament nonabsorbable sutures did not differ significantly from the incidence of infection of tissues subjected to multifilament sutures made from the same material. Coating the multifilament suture with either silicone, wax, or Teflon did not alter the incidence of early infection in the contaminated tissue. Finally, the presence of even the least reactive suture in contaminated subdermal tissue potentiated the development of infection.
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  • 2
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 8 (1974), S. 163-173 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Experiments were conducted to further the understanding of tendon reconstructive surgery.A series of 20 dogs was used for replacement of the forepaw extensor carpi radialis tendon (a single tendon only is present in the dog) with active gliding tendon implants. The implants were attached distally and proximally so that new tendon prosthetic designs could be studied as well as new sheath development under gliding conditions.The results, recorded in this paper, show that a “gliding implant” can convert a nonspecific bed of connective tissue or scar into a specific living envelope comparable to a tendon sheath system. This system has been shown to be capable of lubricating and supporting a gliding artificial implant while augmenting normal tendon function. Degrees of active and passive gliding can take place for indefinite periods, providing the mechanical and dynamic capabilities of the new system are understood and controlled. The mature sheath will show a predictable physiologic response to unfavorable stimuli.Further evidence that the new gliding system functions as a physiologic sheath is borne out by the fact that the implant can be replaced in Stage II by a long free tendon graft. The graft is apparently supported in part by fluid nutrition and filmy adhesions between the distal and proximal anastomosis.
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  • 3
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 8 (1974), S. 365-371 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The mandibular staple is an endosseous implant that will permit the attachment of a lower deture in cases of severe alveolar bone atrophy. It is placed through a submental incision and inserted into seven parallel holes drilled into the mandible. A curved bar containing seven pins is inserted in the holes and is place against the inferior border of the mandibular symphysis. The two lateral most pins project into the mouth and the five retentive pins remain completely buried in bone. Two fasteners are screwed down on the threading of the intraoral pins. Later a bridge containing Dalbo attachments is cemented to the fasteners which allow attachment to a lower denture. A series of 25 patients have been completed with 20 successful patients for survival rate of 80%. The longest case has been in for five years and the average case has been in for 3 years. Stainless steel, titanium and ceramic coated titanium has been with apparently equal success. Patient acceptance has been excellent.
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  • 4
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 8 (1974), S. 391-399 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A study sponsored by the National Institute of Dental Research has as its major goal the development of easily fabricated and implantable dental anchors for replacement of missing or extracted teeth. Tissue ingrowth fixes the anchors in the mandibular or maxillary bone where they can serve as a base for future attachment of prefabricated dental caps, bridges, or other dental prostheses. More immediate objectives are to determine the suitability of specific porous titanium and ceramic materials for anchor applications, to develop satisfactory designs and fabrication procedures for producing these devices, and to define material/bone interface bonding characteristics through in vivo studies. The value of the Hanford Miniature Swine as a human analog for dental research is being assessed concurrently.
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  • 5
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 8 (1974), S. 49-64 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A series of nonporous glasses and glass materials designed with controlled surface ion activities to allow chemical bonding to bone are described. Surface reactivities of these materials in vitro are correlated with biological activities in vivo and in tissue culture. Direct chemical bonding of the materials to bone is demonstrated. The mechanism for development of this bond is through the production of an amorphous ion surface gel on the bioglass. This gel induces osteogenesis by a chemotactic response of osteoblasts.
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  • 6
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 8 (1974), S. 99-113 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: One method of providing an artificial limb for an amputee might be to attach the external prosthesis directly to the skeleton but a major problem is the behavior of the tissues at the point where the prosthesis penetrates the skin surface. Preliminary experiments have been carried out using small flexible implants in porcine skin to study the principles involved. It is confirmed that the epidermis grows down into the dermis around the nonporous materials and the implant-skin junction is unstable and readily becomes infected. It was found that polytetrafluorethylene with pores of 10 μm diameter and hydron sponge with pores of 40 μm diameter became invaded by fibrous tissue and this appeared to prevent the migration of epidermis alongside the implants and a stable ring of epidermal tissue was formed near the skin surface. A review of other situations where epidermal migration is taking place suggests that epidermis is able to migrate through damaged collagenous tissue, possibly with the help of leucocytic enzymes, but that epidermal cell movement is halted when the epidermal sheet is confronted by heathly collagen bundles.
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  • 7
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 8 (1974), S. 145-153 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Polymeric materials are becoming increasingly popular as prosthetic materials in orthopedic surgery. One of these materials, polyethylene, is capable of being fabricated in a porous form suitable for tissue ingrowth. Porous polyethylene appears to be well suited for prosthesis attachment when bonded to its solid form of other prosthetic materials. Extensive bone growth into porous cylindrical specimens implanted in the canine femur has occurred as early as four weeks. Ingrown tissues appear normal and there is minimal inflammatory response. Mechanical strength of the porous material, though not as great as that of the solid material, does appear to be sufficient for certain orthopedic applications. Current research is directed toward determining interfacial strengths and the mechanical properties of the porous polyethylene-bone composite.
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  • 8
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 8 (1974), S. 185-196 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: An investigation was conducted to determine the general physical characteristics of self-curing acrylic resin systems in terms of their potential utilization in total hip arthroplasty.Exothermic temperature, working and setting times were monitored with thermocouples placed in acrylic masses insulated via a Teflon mold. Mechanical strengths were run in an Instron testing machine. The same trends were noted in all systems studied.As thickness or mass increased, the maximum temperature and the setting time increased. As the powder to liquid ratio increased (thereby relatively less liquid), the maximum temperature, set times and dough times decreased, while the working time was essentially unaffected. As the ambient temperature decreased, the maximum temperature decreased while the dough, working and setting times increased.The mechanical strengths of the systems cured at one atmosphere are low compared to high temperature and pressure curing. Flowability of the materials decreases quickly as final set time is approached.Although trends are similar in many self-curing acylic systems minors shifts in complex proprietary compositions can produce a wide span or working and setting times. Because the surgical team controls such parameters as the mass employed, the amount of liquid introduced, and the ambient temperature it is important that they continuously re-evaluate their handling procedures particularly if new acrylic cements would be introduced.
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  • 9
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 8 (1974), S. v 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
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  • 10
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 8 (1974), S. 271-283 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Through a survey of hip replacement arthroplasty the paper establishes the case for objective evaluation of these joints in the patient. It then outlines a simple, non-invasive technique, based on Paul's (1967) locomotion studies, to assess pre- and postoperative functional capability. Preliminary results which establish viability of the procedure are presented.
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  • 11
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 8 (1974), S. 319-328 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A porous titanium alloy called void metal composite (VMC) was investigated for use in knee prosthesis fixation. The interfacial ingrowth fixation of VMC intrameduallary, subchondral, and variable density implants in goat femora was evaluated biomechanically and histologically at six weeks and five months. Biomechanical tests were done under static shear and dynamic, cyclic (fatigue) loading conditions. Readily identifiable bone, strong fixation, and excellent biocompatibility were typical. Some subarticular implants appeared to induce normal hyaline cartilage overgrowth.
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  • 12
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 8 (1974), S. 87-90 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
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  • 13
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 8 (1974), S. 97-117 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A significant variation occurred in the inflammatory response to polyethylene and polyurethane when embedded subcutaneously in experimental animals. This variation apparently is related to the composition of the plastic and adsorption of proteins. The attraction of polymorphonuclear leucocytes by plastics apparently is related to the electrostatic and/or electrokinetic imbalance that occurs at or near the site of implantation.Polyurethane and polyethylene were selected for this study since preliminary observations had shown a variation in inflammatory response when they were embedded subcutaneously in the mouse. From this study it is evident that: (1) variations occurred in the inflammatory reaction in the subcutaneous tissue of mice and rabbits following the embedding of polyethylene and polyurethane; (2) polymorphonuclear leucocytes began to emigrate within hours after these two plastics were implanted, reaching their maximum number within 24 to 48 hr; (3) polymorphonuclear leucocytes usually were absent after the 6th experimental day in mice with polyurethane, but were present for 232 days in mice with polyethylene; (4) polymorphonuclear leucocytes were present in the rabbit for only a few days following subcutaneous implantation of polyethylene and polyurethane; and (5) leucocytes around the implanted polyurethane in the rabbit began to degenerate within 48 hr. The mechanism for this degeneration is not known.
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  • 14
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 8 (1974), S. 185-188 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
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  • 15
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 8 (1974), S. v 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
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  • 16
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Two types of dense Al2O3 ceramics (99.6% purity, 96% purity) were tested in the following fields of interest.1Wear resistibility using a pin and disk method under distilled water and human synovial fluid. Both types showed minimal initial corpuscular wear.2Biocompatibility of ceramic wear particles in mice and rats after injection by different ways. The crystal material is permanently deposited in macrophages, after transport via lymphpatic and blood vessels also in the RES without chronic inflammatory and progressive fibrotic response.3Under moderate stress conditions ceramic plates are fixed firmly by new bone formation within 2-3 months according to tetracycline label studies of bone growth in rats.4A new ceramic total hip prosthesis with two different socket designs for cement free fixation in bone is proposed and used in sheep experiments. The results of a 4 month experiment is presented showing firm fixation of the prosthesis under full stress conditions.
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  • 17
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 8 (1974), S. 85-97 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A study of the tissue compatibility of aluminum oxide implants under different stress conditions in rabbits was performed over four- and eight-week implantation periods. The specific objectives were to examine endosteal bone ingrowth into aluminum oxide coneshaped plugs in amputated tibiae, while additional pellet-shaped implants in the tibiae and femora of rabbits with amputated and nonamputated limbs were studied to determine: (1) if the degree of loading placed on the amputated limb was sufficient to promote bone activity, (2) the degree of inertness and/or toxicity of the aluminum oxide implants, and (3) a possible cause of bone spurs.The results of the radiographic, histologic and microradiographic analyses of the in vivo implants demonstrated that there was little mineralized bone ingrowth into the coneshaped aluminum oxide implants in the amputated tibiae. The study also showed that the aluminum oxide pellet implants in the tibiae and femora of the nonamputated limbs demonstrated excellent mineralized bone ingrowth into surface and internal pores. By comparing these results with the incomplete ingrowth into corresponding pellet implants in the tibiae and femora of amputated limbs, it was determined that a lack of weight bearing and damage to the musculature and vascularity following amputation were interfering with the normal bone activity and therefore bone ingrowth.Angiographs and radiographs of the amputated tibiae demonstrated that bone spurs were present and that they originated at the site of the periosteal damage. Their cause was believed to be associated with an increase in the vascularity of the adjacent tissues.
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  • 18
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 8 (1974), S. 137-144 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Ceramic materials for permanent implantation in osseous tissue, called osteoceramics, were based on an equimolar mixture of Ca3(PO4)2 and MgAl2O4. Tooth roots with dense regions and with regions of controlled porosity for tissue ingrowth were made from the material. They were implanted submucosally in the mandible and maxilla of dogs. Tissue response was aceptable and strong attachment occurred. Thin sections are presented showing the interface of the alveolar bone and the prosthesis.
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  • 19
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    Journal of Biomedical Materials Research 8 (1974), S. 155-162 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Clinical studies will permit only small sections of tendon sheaths to be removed for biopsy at restricted levels as the sheaths were to be used for tendon grafting. In active gliding programs, biopsy has been limited to small sheath sections in immediate relation to the distal or proximal anastomosis where gliding motion may be induced or minimal. In the passive gliding programs, biopsy has been limited to the most proximal segments where considerable folding of the sheath occurs or cul-de-sac buckling of the implant may produce irritation.As these were the only practical clinical sources of sheath sections for biopsy and study, the authors felt that a comparison study of sheath development in animals would broaden our understanding in humans. With this objective in mind, three canine laboratory studies were carried out where, for pure purposes of investigation, entire sheath sections were removed at designated time intervals for study.The flexible implants were well accepted, affording the opportunity to observe development of early sheaths in a controlled connective tissue environment, free from the stress of joint motion.The semi-rigid implants showed equal acceptance in side-by-side tissue level of the same dog as the flexible implant. This influenced changes in artificial tendon development from extrusion to the more exacting mold fabrication. It seemed evident that the degree of increase in stiffness of the new artificial tendons to gain a superior surface for gliding and increased strength would not change tissue acceptance providing flexibility was maintained.The cellular response in this study did not seem to represent a foreign body phenomena but an orderly acceptance of the soft tissue environment to the smooth surface of the inert implant.It is concluded that this study confirmed in animals the clinical findings of Mayer, Bunnell, Milgram, and Carroll.The consistent orderly development of the new sheaths formed in response to the static implants is impressive. The authors believe the appearance of these histologic sections are likely correlations with the development of new sheaths around the Hunter Tendon Prosthesis during the three-four week postoperative period when the hand is resting in a functional dressing.
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  • 20
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 8 (1974), S. 197-207 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Poly-α-amino acids have been investigated for possible use in a wide variety of biomedical applications. These range from dialysis membranes to artificial skin substitutes to degradable sutures. The large number of available α-amino acids potentially provides an extremely large number of poly-α-amino acids. The majority of materials investigated to date are copolymers composed of two components, one of which usually provides the desired property for the given application.This paper deals with the further examination of a series of γ-benzyl-L-glutamate-L-leucine copolymers. Evidence is provided on the effect of these copolymers on the biological environment as determined by implantation in rats up to 200 days. In vitro tests were also performed and the effect of these tests on the stress-strain properties of one of the copolymers is presented.Preliminary evidence on biodegradable copolymer films is also included. These materials have free γ-carboxyl groups on the glutamate components.
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  • 21
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 8 (1974), S. 427-434 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Following the classification of tissues according to their “dominant” and “interactive” components the paper surveys their load-deformation behavior, highlighting in particular the significance of time dependence. This leads to a discussion of the implant/tissue interaction in which the complexity that could be created by varying load and deformation time rates at the interface is explored.
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  • 22
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The management of severe flexor tendon injuries of the hand has been dramatically improved by tendon sheath reconstruction with an artificial tendon, followed by conventional tendon grafting. The purpose of this study was to investigate the nature of neosheath formation.In 25 chickens, the flexor tendons and sheaths in a toe were excised and replaced with a United States Army artificial tendon. An artificial tendon was also placed in the back, and four weeks later, tendons and surrounding tissue as well as normal tendon sheaths were excised and submitted for light, transmission electron microscopy and scanning electron microscopy.In all instances, neosheaths formed around the silastic coated artificial tendon. The neosheaths formed in the foot and back were similar to normal sheath, having the same cellular and fibrous composition. Reconstruction of the normal anatomy with an artificial tendon explains why this surgical technique gives superior results to other less physiologic procedures in patients with severe hand injuries.
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  • 23
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    Journal of Biomedical Materials Research 8 (1974), S. 219-226 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The biomaterials engineer of today has an extremely limited choice of approved metallic implant alloys with which to conduct his studies. There is essentially no incentive for larger companies to initiate basic research in the biomaterials field. New alloys which would have the best chance of developing as biomaterials would be “spin-off” alloys from somewhat related industries and currently in production. MP35N is just such a spin-off alloy with a background of years of in-vitro testing and use in corrosive environments. When compared to the desired implant material requirements, the material properties required of MP35N for present applications readily indicate its potential use as a biomaterial.It is a castable alloy which exhibits good as-cast ductility. In the wrought condition, yield strength levels from 60,000 to over 310,000 psi are possible with accompanying good ductility characteristics. Excellent stress corrosion cracking resistance and improved fatigue strength over present cast implant material are also characteristic of MP35N. Results, to date, from in-vivo tests indicate tissue compatibility of MP35N at least comparable to HS-21 (Vitallium).Possible medical applications for MP35N would include hip and knee joints, bone plates, heart pacer electrodes, suture wire and clips, and Endosseous blade implants.
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  • 24
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    Journal of Biomedical Materials Research 8 (1974), S. 285-288 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The bone-implant interface and the accompanying difficulties with fixation continue to be a major area of research activity. Biological fixation would appear to be the ideal method of fixation. Press-fit metal implants may be part of a larger answer that may include sintering, coatings, or both.
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  • 25
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    Journal of Biomedical Materials Research 8 (1974), S. 27-38 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Substantial improvements have been made by the surgical manufacturing industry in the development of implants and by the orthopedic surgeon in the use of prosthetic appliances. In spite of these advancements, some prosthetic devices completely fail of do not provide satisfactory performance. Hostile environmental conditions of the human body are highly influential in limiting the service life of the implants, so the material selection and the design and fabrication must be made with extreme care. Examinations we have made of intramedullary pins retrieved from femurs reveal examples of fretting and/or crevice corrosion and in-service failures that nucleated in microscopic surface gouges. Self-tapping screws, essential for securing bone implants, failed due to fractures originating in the thread roots. Failures by merely exceeding the ultimate strength of the material and by the more involved process of stress corrosion cracking are shown.An evaluation laboratory for failure analyses of prostheses is recommended.
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  • 26
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    Journal of Biomedical Materials Research 8 (1974), S. 65-76 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A comprehensive protocol is presented for the in vivo evaluation of soft tissue foreign body reactions to surgical implants. A number of methods of evaluation and quantitation of the tissue reaction to implants are presented and discussed. A strong plea is made for semi-quantitation of tissue reactions, rather than relying on subjective, qualitative methods.
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  • 27
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    Journal of Biomedical Materials Research 8 (1974), S. 227-244 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Total hip replacements are based on a long chain of efforts of partial exchange of joint compartments. Inplants of material of both biological and nonbiological origin have been applied over the past 50 years. Smith-Pedersen, Judet, Moore, and Thompson are names to be remembered. It was primarily from the idea of firm fixation and low friction between the joint surfaces that today's constructions emerged. Immediate superior clinical results encouraged a strong trend towards hip-arthroplasties. The orthopedic surgeon can now choose amongst several prosthetic designs, the most common being metal to metal or plastics with or without bone cement. But, after ten years a number of threatening problems have become evident, calling for critical analysis of total joint replacements. Biomechanical, chemical, and morphological disturbances, both in the early and late phases, show that the body has difficulties in tolerating the artificial joint. This survery presents some of the most obvious risks and failures in total hip replacements.
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  • 28
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    Journal of Biomedical Materials Research 8 (1974), S. 245-260 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The surface replacement hip prosthesis reported represents an attempt to improve upon some aspects of the present design of total hip. The prosthesis comprises a cap fitted over the femoral head and a liner fixed into the socket, both being cemented with methyl methacrylate. The chief advantage of this design is preservation of bone stock. The prostheses were inserted bilaterally into six dogs, and whilst ten joints failed, one case was strikingly successful at two years follow-up. It was concluded that the design showed sufficient advantages over current total hips and that there was sufficient possibility of success in some application, to merit further study.
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  • 29
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Total replacement of the knee joint often remains unsatisfactory because of severe femor-patellar osteoarthritis.Twenty-four Walldius knee prostheses were inserted in 21 cases. Since March 1971 we have used a combination of this type of hinge prosthesis with a high-density polyethylene retropatellar facet prosthesis developed by our group in cooperation with the Badische Anilin- & Soda Fabrik AG (BASF).Fourteen knees of this combined type have been implanted and resulted in considerably less complaints than the original Walldius knee. The postoperative range of motion with an average of 66° does not differ in both groups.
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    Journal of Biomedical Materials Research 8 (1974), S. 329-330 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Although degenerative arthritis of the shoulder is quite rare, it does occur. Pain relief was obtained in three such cases by the insertion of a polyethylene glenoid liner made for this purpose and used in conjunction with a standard metal prosthesis for humeral head replacement. Good pain relief and fair motion was obtained.
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    Journal of Biomedical Materials Research 8 (1974), S. 341-356 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: An in vitro test cell is described which permits exposure of artificial surfaces in sheet or film form to native human blood in the absence of a blood-air interface. Evaluation of Cuprophane, polyethylene, Silastic, and silicone-coated glass in the in vitro cell showed Cuprophane and silicone-coated glass to produce the least activation of the intrinsic coagulation system, while Silastic produced the greatest degree of activation. Polyethylene gave results intermediate between those obtained with the other materials. Each of these four different materials was evaluated in the elliptical cell test system multiple times with blood from 13 different donors.Our data suggest that with the present test system and the proper experimental design, one might expect that, “on the average,” performance of 36 tests on each of two materials will be sufficient for a 10% difference in their compatibility with blood to be statistically significant at the 5% level. The number of tests is 26 for significance at the 10% level.
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    Journal of Biomedical Materials Research 8 (1974), S. 375-379 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A polyelectrolyte synthesized from cis-1,4-polyisoprene, containing aminosulfonate and carboxylate groups was shown to have an anticoagulant activity of about 1/30 compared with heparin. Because the substance prevents the coagulation of plasma in the presence of thrombin it is assumed that it acts as an antithrombin.
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    Journal of Biomedical Materials Research 8 (1974), S. 407-419 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Using a metallographic technique to identify and count corrosion pits, the tendency for passive film breakdown has been studied under conditions that simulate a crevice and a combination of two different materials. Potential corrosion couples were formed among: 316L stainless steel, cast Co—Cr—Mo alloy, wrought Co—Cr—W—Ni alloy, Ti-6% Al-4% V alloy, a Co—Ni—Cr—Mo (multiphase) alloy and graphite. Only 316L stainless steel seems significantly prone to pitting corrosion in a crevice condition. Dissimilar metals in the crevice configuration did not seem to accelerate the corrosion of stainless steel.
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    Journal of Biomedical Materials Research 8 (1974), S. 451-470 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: This paper describes a novel approach for obtaining covalent bonding to tissues by chemical grafting of polymeric side chains to the collagenous backbone. Soft tissues such as calfskin or ratskin can be modified by acrylic, methacrylic, or vinyl monomers containing a variety of functional groups using ceric ions, persulfate-bisulfite or comonomers forming donor-acceptor complexes as initiators. Reactions take place within 20 min to 3 hr under experimental condition which, with suitable changes, might be tolerated clinically. The resulting products are insoluble in solvents for the respective homopolymers. It is likely that the polymeric side chain is attached chemically to the collagenous backbone. With ratskin, the grafting takes place mainly at the surface, resulting in a change in wettability and water sorption of the substrate. Modified hydrophilic, hydrophobic or even oil repellent surfaces can be prepared by judicious choice of monomer used. Thus, hydrophobic, oleophobic subdermal ratskin surfaces are obtained on reaction with flourinated monomers. Treated ratskins appear more resistant to fungal attack than the original substrate. It is conceivable that the polymeric side chains can serve as adhesive liners since the modified surface may improve the ability of the substrate to adhere to restorative materials.
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    Journal of Biomedical Materials Research 8 (1974), S. 373-383 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: This report is concerned with the two tissue types (oral epithelium and fibrous connective tissue) which surround oral implants and the possible adhesion of cells of these tissues to the implant surface. A review of the literature reveals that there is disagreement as to which of these two tissue types encase the deeper portions of Vitallium implants. Using techniques developed for studying the dental epithelial attachment, the following observations are submitted.1A PAS-possitive material is in abundance at the interface between the junctional epithelium and the implant post and present, but to a lesser degree, between the fibrous connective tissue and the implant surface.2An Oracine-positive material is present at the interface of both tissue types and the implant surfaces.3Collagen fibers subjacent to the junctional epithelium are oriented at functional angles to the basement membrane.4A histological artifact has been frequently observed which is the result of the tearing of the end of the epithelium away from its basement membrane.5Bacterial plaque adhering to the exposed portion of the implant posts extends in an apical direction and terminates abruptly along a very distinct line.From these observations it seems likely that an adhesion exists at the interface between the junctional epithelial cells and the penetrating implant surface.
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    Journal of Biomedical Materials Research 8 (1974), S. 299-309 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: This paper reviews the first 35 cases of geometric total knee arthroplasties performed on 32 patients at The George Washington University Medical Center. The procedure was done in 25 patients with rheumatoid arthritis, 5 patients with osteoartritis, and 2 patients with traumatic arthritis. Ages ranged from 38-83 years with an average of 58 years. This is a short-term follow-up with the longest of one year duration and the shortest two months. Fourteen patients had previous knee surgery including one that had three previous procedures. Indications and contraindications are outlined and the surgical procedure is described with an effort to point out certain technique problems. Twenty patients had complete relief of pain, ten had slight pain with activity. One has severe patellofemoral pain on weight-bearing and one has constant pain. Twenty patients had varying degrees of instability prior to surgery and none following the procedure and a 50° valgus deformity has been corrected satisfactorily. It was observed that patients with restricted motion and pain gained significant motion and pain relief while those with good motion and pain gained less overall and in some instances lost. Peroneal nerve palsies, patellar tendon avulsions, and wound complications are presented. We feel on the basis of this limited experience that this total knee system offers to the patient in need of a salvage procedure a stable, essentially pain-free knee that has increased mobility and function.
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    Journal of Biomedical Materials Research 8 (1974), S. 349-363 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Maxillofacial prosthetic materials are classified in two main groups: extraoral and intraoral prosthetic materials.Among extraoral prosthetic materials vinyl chloride polymers, poly (methyl methacrylate), silicone, and polyurethane are discussed for use in facial prosthetics. At present silicones and polyurethane materials are considered most desirable for their strength, even though both are somewhat difficult to color.Intraoral prosthetic materials include silicones, poly (methyl methacrylate), Tantalum, Ticonium, Vitallium, and Titanium mesh materials. Here again, silicone is particularly valued for its tissue tolerability. Metallic mesh materials have the advantage of permitting granulated tissue to migrate through the mesh.The criteria for ideal materials in maxillofacial prosthetics are as follows: extraoral prostheses should not irritate the surrounding tissues, yet it should be strong enough about the periphery to endure. It should be translucent, light weight, easy to process, and easy to manipulate prior to processing. It should be resistant to various chemicals such as ether, oil and to sunlight, heat, and cold.Implantable prosthetic materials must not be physically modified by the soft tissue; must not be capable of inciting inflammatory or foreign body reaction; must be chemically inert, noncarcinogenic, capable of resisting strain, easy to construct, and easy to sterilize.Progress toward meeting these criteria depends upon cooperation between laboratory and clinical researchers.
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    Journal of Biomedical Materials Research 8 (1974), S. 401-407 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Titanium implants have been designed which utilize a solid core and porous exterior. The technique for implants containing posts utilizes a cast chromium-cobalt splint for fixation and the buried implants are held in place by the overlying gingiva until tissue growth into the porosity results in stabilization.Clinically successful post implants with apparent bone ingrowth and healthy gingiva surrounding the post have been achieved for periods up to three months.
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    Journal of Biomedical Materials Research 8 (1974) 
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    Journal of Biomedical Materials Research 8 (1974) 
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    Journal of Biomedical Materials Research 8 (1974), S. 357-367 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: Medical grade silicone rubber manufactured by Dow Corning Corporation was implanted subcutaneously in beagle dogs. At specified time intervals, the implants were removed at which time physical properties and weight changes were determined. A change in the physical properties was observed after six months implantation. Tensile strength decreased 7%, elongation 10% and the modulus at 200% extension increased 8%. After two years implantation, tensile strength had decreased 8%, elongation 15%, and 200% modulus increased 16%. After two weeks implantation, a 0.4% weight gain was seen, and after four weeks implantation the samples had gained 0.7%. However, after four weeks the weight gains stabilized and from four weeks to two years, they never exceeded 0.91%. The increase was due mainly to lipid absorption. No phospholipid or protein was detected. A chloroform/methanol extraction of the samples before implantation demonstrated 1.7% extractable silicone polymer. Samples not extracted before implantation, but extracted after implantation also demonstrated 1.7% extractable silicone polymer. This data suggests extractable silicone polymer does not leach from the medical grade silicone rubber during implantation.The data also suggests that the rubber is not being degraded to extractable silicone polymers during implantation. There were no significant differences in percent lipid up-take or the lipid profiles between samples which had extractable silicone polymer extracted before implantation and/or those which were not extracted before implantation.It should be pointed out that the slight changes in physical properties measured in this study should not be great enough to alter the performance of the rubber in the subcutaneous environment.
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    Journal of Biomedical Materials Research 8 (1974), S. 399-406 
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    Notes: Teflon implants containing a single cylindrical pore were surgically embedded in the femural bones of rabbits. A total of eight different pore sizes were used for each experimental animal. Their diameters ranged from 274 to 670 μm, with approximately 50 μm intervals between sizes. The amount of bone tissue ingression and its spatial distribution was assessed for each pore diameter at weekly intervals over a sixteen-week period by bone labeling with Tetracycline injection. From these data an optimum pore diameter of between 400 to 450 μm was observed for maximum bone ingression. The distribution of new bone growth was characterized as an apposition pattern which emanated from the walls and the open end of the pore. No rejection phenomena were observed at the Teflon tissue interfaces.
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    Journal of Biomedical Materials Research 8 (1974), S. 443-450 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: The integrated intensities of certain reflections of the γ, γ1, and γ2 phase have been determined as a function of the mercury content of 6 amalgams after annealing for 20 hr at 37°C. This dependency could be described satisfactorily by means of the regression model: \documentclass{article}\pagestyle{empty}\begin{document}$$ I_i = I_{i^0 } - \alpha _i W $$\end{document}. Here Ii is the integrated peak intensity for phase i at a mercury fraction of W by weight, whereas Ii0 and αi are constants of the material, whereby i = 0, 1, 2 stands for the γ, γ1, and γ2 phase respectively. Considerable differences between the αi and Ii0 parameters of the different amalgams were detected.
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    Journal of Biomedical Materials Research 8 (1974), S. 209-217 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Carbon is one of the most attractive biomaterials in many respects. Recent developments in high strength carbon materials for the aerospace industry have led to new forms of carbon which have good structural properties. Several of these, based on a vapor-de-posited pyrolytic graphite matrix, are described. A needle-like silicon-carbide strengthened pyrolytic graphite has been implanted in rabbits and chimpanzees with encouraging results. Applications are being sought.
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    Journal of Biomedical Materials Research 8 (1974), S. 3-10 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: Strength, dimensional change during setting, and corrosion resistance have been measured for amalgams prepared from splat-cooled alloys of different compositions in the Ag-Sn-Cu system. The amalgam with optimum values of these properties was made from the alloy containing 60 at. % Ag, 25 at. % Sn, and 15 at. % Cu. Tensile strengths for amalgams from this alloy were about 8000 psi, dimensional change during setting near zero, and corrosion resistance was good.X-Ray diffraction showed that the γ1 and γ2 phases formed during the early stages of setting but that the γ2 phase had essentially disappeared after about 24 hr. At the latter time Cu6Sn5 was present.
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    Journal of Biomedical Materials Research 8 (1974), S. 45-51 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: Permeation parameters of four anti-tumor drugs across membranes prepared from hydrophilic methacrylate gels were measured and compared with the permeation of NaCl. It was found that by increasing the ratio of butyl methacrylate (BMA) to hydroxyethyl methacrylate (HEMA), the rate of diffusion can be lowered to practically zero at 20% BMA. However, this decrease is different with various drugs due to the interaction of the drug with the gel. Differences by a factor of two were found in our set of drugs. Therefore, each new drug should be tested in this way. In addition a routine testing of dialysing devices by an NaCl solution is suggested as a method for detecting technological imperfections and calibrating the deviations from standard parameters. A chemical modification of the membrane is recommended as the best way for controlling the permeation rate.
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    Notes: The purpose of this study was to determine the effect of air-borne gaseous impurities, introduced during trituration, on the strength of amalgams.Four experiments were conducted. Each experiment consisted of a control group (1) in which the amalgam was triturated in air and an experimental group (2) in which the amalgam was triturated in argon, an inert gas. Standard specimens yielded mean diametral tensile strengths of 5950 psi (1) and 6603 psi (2). Hand compacted specimens yielded mean diametral tensile strengths of 5829 psi (1) and 6412 psi (2). Standard specimens yielded mean compressive strengths of 46,636 psi (1) and 47,269 psi (2). Specimens compacted hydraulically yielded mean uniaxial tensile strengths of 10,928 psi (1) and 11,660 psi (2).Statistically, the differences between the means for each experiment are significant. Hence, trituration in an inert gas has been shown to be an effective method for increasing the strength of amalgam.
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    Notes: A new prosthetic material, ultra-high molecular weight (UHMW) polyethylene graphite, was developed for use in total joint replacement and found to exhibit 1/7-1/30 lower wear rate than UHMW polyethylene bearing against Vitallium alloy.A preliminary study was undertaken to test the biocompatibility of the new material. Specimens of 316L stainless steel, high-purity graphite, UHMW polyethylene, and the composite material were implanted in rabbits and cynomologous monkeys. The materials were evaluated in both solid and particulate forms after implantation in bone, joint cavities, and paravertebral muscles. The tissue reactions to the materials were noted at time intervals from 6 weeks to 1 year.All materials showed good tissue acceptance in solid form. The UHMW polyethylene and the composite material were noted to be more reactive than either the high-purity graphite alone or the stainless steel when in particulate form.The eventual use of the polyethylene graphite composite in total hip arthroplasties is suggested by virtue of its identical biocompatibility with UHMW polyethylene. In addition, its superior wear resistance, and hence low volume of wear debris particles presented to the surrounding tissues would offer an advantage in terms of longevity of the implant both mechanically and biologically.
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    Journal of Biomedical Materials Research 8 (1974), S. 291-297 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A thermochemical-photochemical bifunctional reagent was used to immobilize asparaginase under very mild reaction conditions. Stability and specificity tests indicated that the photochemically immobilized enzyme products were unique only in their high speific catalytic activities.
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    Journal of Biomedical Materials Research 8 (1974), S. 199-211 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: A brief discussion is presented of some of the problems and artifacts inherent in the testing of soft tissue reactions to artificial implants. The process of inflammation and wound healing is presented. The various factors affecting the foreign body reaction (chemical, mechanical, geometrical, and others) are discussed. The cellular components of the foreign body reaction are described and the sequential cellular changes that may occur as a result of implanting an artificial device are examined. The foreign body reaction should be considered as a chronic inflammatory response.
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    Journal of Biomedical Materials Research 8 (1974), S. 251-259 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Adsorption of albumin, γ-globulin, and fibrinogen from solution, under both static and flow conditions, onto several hydrophobic polymers was studied using internal reflection infrared spectroscopy. Isotherm curves experimentally found were consistant with Langmuir type adsorption. The rate and amount of protein adsorbed was found to be dependent upon both the nature of the polymer substrate and on the flow rate of the solution.
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    Journal of Biomedical Materials Research 8 (1974), S. 283-289 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: The reactivity of porous Vitallium in vivo and in vitro has been tested. Samples have been implanted subcutaneously and intramuscularly in Wistar Rats for periods of up to two years. No untoward tissue reaction was found, and the samples did not show any evidence of corrosion. Samples have also been tested in an electrochemical cell. No increase in reactivity for unit surface area was found.It is therefore concluded that porous Vitallium is a safe, inert material, and is acceptable for use in clinical practice.
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    Journal of Biomedical Materials Research 8 (1974), S. 321-338 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The use of conventional rigid metal plates (modulus of elasticity 30 × 106 psi) for internal fixation of difficult long bone fractures may paradoxically weaken the fractured bone through a process of osteoporosis secondary to protection of the bone from stress. The hypothesis being studied which has stimulated the present work is that a new composite plate made of less rigid material but with similar geometry to stainless steel plates may promote fracture union without the complication of osteopenia. This new composite material has a modulus of elasticity similar to that of bone (approximately 3 × 106 psi) which is more than an order of magnitude lower than that of stainless steel, yet the fracture strength of this new composite material (35,000 psi) is approximately one-half that of stainless steel.The ability to fix diaphyseal fractures by composite plates was studied by implanting these plates in the left (experimental) radii of six dogs with transverse mid-shaft osteotomies. The right (control) radii had similar transverse osteotomies, but were plated by conventional metal plates equal in size to the new composite plates. Four months postsurgery, all experimental and control fractures had healed.Biomechanical tests of the excised radii using a torsional loading apparatus showed there were no significant differences in strength, fracture energy, angular deformation, or maximum shearing stress when comparing the experimental to the control radii. The results are sufficiently promising to warrant additional long-term experiments investigating this concept of internal fixation.
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    Journal of Biomedical Materials Research 8 (1974), S. 393-398 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: A mechanism of platelet adhesion to foreign surfaces is proposed which involves the formation of enzyme-substrate complex bridges between platelet glycosyl transferases and surface-adsorbed glycoproteins. To test this hypothesis two experimental approaches were attempted. The first, in vitro, series of experiments assayed two glycosyl transferases using adsorbed plasma proteins as acceptors. Sugar-nucleotides could be transferred onto adsorbed gamma globulin and fibrinogen but not onto adsorbed albumin. The second group of experiments quantitated platelets adhering to tubing coated with protein and subjected to treatment to remove different carbohydrate residues. Using whole unheparinized ovine blood, more platelets adhered to fibrinogen or gamma globulin coatings which had been either desialyzed or had both sialic acid and galactose removed than to the same coatings when untreated. These data, plus that of other workers, give support to the proposed mechanism.
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    Journal of Biomedical Materials Research 8 (1974), S. 421-434 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Kinetic concepts of reducing exothermal effects during curing of biomedical acrylic resin systems are discussed. The effects of addition of 1, 4-cyclohexadiene and cyclohexylmethacrylate to the monomer on the temperature rise in cold- and heat-curing resin have been determined. Both compounds appear to be effective in damping the temperature peaks. Screening of compressive strengths and residual monomer determinations revealed that addition of cyclohexadiene results in a less complete polymerization than in the case of cyclohexyl methacrylate modified resins.
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    Journal of Biomedical Materials Research 8 (1974), S. 471-485 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Thermal conductivities were determined for five commercial composite restorative materials, one composite crown and bridge cement, two cavity “bases,” and poly(methyl methacrylate). In addition, the effect on thermal conductivity of concentration and type for five resin-reinforcing fillers was investigated. Depending upon type and concentration of filler, the composites ranged in thermal conductivity from somewhat less than that for dentin to slightly over twice that value. Because of their good marginal adaptation, the thermal conductivity of composites must either be closely matched to tooth structure or a base should be used in deep restorations.
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    Journal of Biomedical Materials Research 8 (1974), S. 487-489 
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    Keywords: Chemistry ; Polymer and Materials Science
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  • 59
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    Journal of Biomedical Materials Research 8 (1974), S. 221-230 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The membrane surrounding the hip joint containing metal endoprostheses were examined in 20 patients using histology and the scanning electron microscope (SEM). No synovial cells were found. The capsule was dense fibrous tissue, covered at the surface with an amorphous membrane of doubtful composition. Several questions have been raised, such as the role of synovial cells in cartilage nutrition, the nature of the fluid in these joints, and secretion into and absorption out of the artificial joint.
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  • 60
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    Journal of Biomedical Materials Research 8 (1974), S. 261-276 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: A process is described for binding brinolase, a fibrinolytie enzyme, to a solid support. Evidence is presented to prove the activity and stability of the bound enzyme at physiological conditions of pH and temperature. A scheme is suggested for preparing suitable material onto whose surface the fibrinolytic enzyme can be bound in an approach to creating a thromboresistant surface.
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  • 61
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    Journal of Biomedical Materials Research 8 (1974), S. 299-319 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Measurements of Haversian osteons in human tibial cortical bone specimens from seven donors demonstrate that, for this study: 1Haversian osteonal area, as a proportion of cross-sectional area of cortical bone, increases with the age of the donor, whether or not the area of the central Haversian canal is taken into account.2Haversian canal area, as a proportion of cross-sectional area of cortical bone, either remains the same or increases with the age of the donor.3The number of osteons present per unit cross-sectional area has no observable age dependence.4The percent inorganic content or cortical bone increases with the age of the donor.Optical studies on thin sections of cortical bone, utilizing crossed polarizing filters, suggest that the classification of osteons as light, dark and intermediate, as proposed by others (Anat. Rec., 161, 377 (1968)) is incorrect in that only one general type of Haversian osteon structure was detected in this study.
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  • 62
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    Notes: Zinc polycarboxylate cement (PAZ) was shown to actively bond to 45Ca in vitro, with maximum uptake occurring at a Ca+2 concentration of 0.2 mg/ml. When the resultant PAZ-45Ca complex was subsequently incubated in the presence of high levels of unlabeled Ca+2, there was an exchange between the 45Ca bond to the cement and the Ca+2 in solution. When PAZ prepared using 65Zn was incubated with high levels of Ca+2, there was no exchange between the Ca and the 65Zn. 14C-PA failed to be taken up by L-cells in tissue culture, during 16 division cycles. Using radioactive PAZ prepared from 14C-PA, the PA moiety of the cement was shown to be extremely insoluble and stable in vivo.
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  • 63
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    Journal of Biomedical Materials Research 8 (1974), S. 155-161 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: In our earlier papers1-4 we reported on the biocompatibility of esters and substituted amides of methacrylic and acrylic acids which are suitable for the development of specific biological functions.5 The results described in these papers1-4 enabled some relationships to be formulated which exist between the chemical and physical structure of the implants, on the one hand, and the process of their healing-in and calcification, on the other.6.A number of biological applications require materials having rubber-like mechanical properties. With this aim we started in our laboratory the development of hydrophilic elastomers based on dienes containing hydrophilic groups. Poly(2,4-pentadiene-1-ol)7 was the first polymer of this type obtained which had mechanical properties suited for biomedical applications. Its biocompatibility with living tissue is reported in this paper.
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  • 64
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    Journal of Biomedical Materials Research 8 (1974), S. 163-183 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: We examined the formation of platelet aggregate emboli and factors that affect platelet aggregate formation and embolization in prototype hollow-fiber membrane oxygenators used to perfuse dogs. Platelet aggregates formed on the inlet surface of the oxygenator. Many aggregates subsequently formed emboli which passed through the fibers and sometimes lodges in them. Aggregates also developed on the outlet surface. Aggregates that adhered to the oxygenator surfaces contained tightly packed platelets having multiple pseudopodia extracellular granules, and occassional fibrin strands and white cells. The number of platelet aggregate emboli found downstream to the oxygenator varied between 0 and 4 emboli/ml blood. These emboli did not contain fibrin and extracellular granules. Platelet aggregate formation and embolization was reduced or eliminated by increasing the dose of heparin or by using a circuit with a large priming volume of albumin solution and a large surface area oxygenator.
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    Journal of Biomedical Materials Research 8 (1974) 
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    Keywords: Chemistry ; Polymer and Materials Science
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  • 66
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    Journal of Biomedical Materials Research 8 (1974), S. 11-34 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: A series of systemic toxicity tests for various types of compounds are presented with illustrative data and discussed in regard to their relevance as potential screening tests for dental compounds and products. In developing and marketing a new dental material, it is important not only to ensure safety for the patient but also for the dentist, dental assistant, and laboratory worker who routinely handles and uses the product. Data are presented on a number of commercially available dental products as well as various chemical entities, which were tested by one or more of the methods described.
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    Journal of Biomedical Materials Research 8 (1974), S. 69-80 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Because the metabolic reaction that gives ethylene oxide its sterilizing qualities also takes place with human protein, it is imperative that any residual gas be removed before the sterilized material is used on the patient. This paper presents a method of estimating aeration time required following sterilization of polyvinyl chloride (PVC) to reduce toxic residues to a desired level. The method proposed involves calculation of the coefficient of diffusivity, and the use of a simplified diffusion equation to estimate aeration time.
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  • 68
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    Journal of Biomedical Materials Research 8 (1974), S. 91-94 
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    Keywords: Chemistry ; Polymer and Materials Science
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  • 69
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    Notes: A controlled surface shear stress produced by laminar flow in a rotating disk or parallel plate flow system has been used to study red cell adhesion to glass, siliconized glass, polythylene and Teflon. The results indicate that the shear stress at the surface must exceed a minimum critical value before cells will detach, and that this minimum critical shear stress increases as the time of cellsurface contact is increased. The results also indicate that the minimum critical shear stress for detachment from clean surfaces correlates with the critical surface tension of the material for the four materials studied. Studies with proteincoated surfaces indicate that albumin causes a moderate reduction in the strength of adhesion. The magnitude of the effect was found to be influenced significantly by the substratum material.
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    Journal of Biomedical Materials Research 8 (1974), S. 189-191 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Journal of Biomedical Materials Research 8 (1974), S. 1-9 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Metallurgical and histological examinations of implants and adjacent tissue removed from orthopedic patients have been performed in a series of 190 cases. The results have been correlated with clinical findings where possible. The two major factors to emerge from this study were that many stainless steel implants corrode in the body and that titanium implants release titanium into the local tissue, which may become discolored.Severe cases of corrosion in stainless steel implants were attributed to faulty manufacturing technique and poor implant usage. This corrosion was frequently associated with crystal-like “microplates” in the tissue and lead to clinically significant effects in some cases. Less severe cases of corrosion were almost invariably associated with interfaces between components. Susceptibility to this corrosion may be minimised by improvements in design and materials specification.Titanium levels in excess of 2,000 ppm were found in the tissue in 3 cases out of 19 analysed, no specimen of a control series showing greater than 100 ppm. Histological sections showed accumulations of intracellular particles of exogenous origin. The evidence that such titanium release and particle accumulation causes clinically significant effects is only minimal but it is possible that systemic distribution of titanium and remote hypersensitivity effects could arise.
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    Journal of Biomedical Materials Research 8 (1974), S. 435-443 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: This paper begins with a brief historical review of the field of biomechanics applied to oral implantology. Based on the current status of development, a set of generalized biomechanical requirements are presented covering analytical, experimental and clinical considerations. The current biomechanics status and requirements are then used to derive a three part role for the biomechanics of oral implantology. The expected benefits to be gained from implementing this role are outlined.
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    Journal of Biomedical Materials Research 8 (1974), S. 213-219 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: A new polymer material has been developed for tooth implants. This material appears to be more successful than previous materials used, in that self support of tooth-replica implants have been demonstrated in baboons. The surface topography of the new material has been studied with a scanning electron microscope and a lace-like pattern was demonstrated, which had certain similarities to the surface of cementum of natural teeth.
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    Journal of Biomedical Materials Research 8 (1974), S. 277-282 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The tensile and flexural behaviors of fresh bovine nasal cartilage were measured as a function of strain rate. The following conclusions may be drawn from these studies: (1) Strain rate increases the measured values of tensile and flexural stress and ultimate tensile strength. (2) The effect of strain rate is minimal under the following subultimate conditions: (a) Rates from 0.045%/sec to 2.2%/sec for tensile stress at 13.4% elongation. (b) Rates from 0.038%/sec to 0.38%/sec for flexural stress at 10% deflection. (3) The average ultimate tensile strength of bovine nasal cartilage increases from 303 psi at .045%/sec to 471 psi at 11.0%/sec, and it extends on the average to 38% before failure. (4) at 20% deflection the average value of the flexural stress is 540 psi over the strain rate of .038%/sec to 38%/sec. (5) It is important that the strain rate used in measuring the mechanical properties of biological tissues be comparable to the strain rates encountered in vivo.The values of the mechanical properties may be a function of the measurement technique. Mechanical properties are measured by exposing the material to deformation applied at a given rate. The data obtained is a function of this rate of deformation (strain rate) and therefore may not be an absolute value to be used for all stress rates. This paper presents the tensile and flexural properties of bovine nasal cartilage and the variation of these measurements with the strain rate.
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    Journal of Biomedical Materials Research 8 (1974), S. 369-373 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: Mercury vapor pressure over clinically used amalgams, as well as the individual phases composing dental amalgam, has been determined from weight loss data using Langmuir's time averaged weight loss technique. The results show that the Hg vapor pressure of 38.2 × 10-6 torr over the pure γ1 (Ag2Hg3) phase is more than an order of magnitude greater than that over the remaining amalgams considered: β1, α1, γ2, Ag-Sn amalgams, True Dentalloy amalgams, Au-containing amalgams, and Dispersalloy amalgams.
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    Notes: The diffusivities of Ag110m and Sn113 in bulk Ag3Sn were measured using the method of Gruzin. The volume diffusion coefficients were determined over the temperature range 200 to 400°C, with temperature dependence given by DV*Ag \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop = \limits_ \cdot $\end{document} 1.03 × 10-3 exp (-22,400/RT) and DV*Sn = 4.01 × 10-4 exp (-22,800/RT) cm2/sec. The fact that silver is the faster moving species in bulk Ag3Sn is important to the amalgamation process. On the other hand, it was found that along grain boundaries, tin tracer atoms diffused faster than did silver atoms. Faster grain boundary diffusion of tin, however, may not be a decisive factor in the actual amalgamation process, since mercury penetration exceeds the migration of tin atoms along grain boundaries.
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    Journal of Biomedical Materials Research 8 (1974), S. 435-442 
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    Notes: The integrated peak intensities of certain reflections of the γ, γ1 and γ2 phase of six dental amalgams at a mercury content of 45 wt% were selected and their dependence on the annealing time (1 〈 t 〈 140 days) at 37°C was determined. Also the overall changes in phase composition were studied qualitatively by means of the peak heights of all phases found in the X-ray patterns of these amalgams at different annealing times.The γ2 phase content did not seem to depend on the annealing time. It was established also that the γ and γ1 phase contents of these dental amalgams decrease with increasing annealing time at 37°C whereas the quantity of another phase, probably the ternary β phase increases with increasing annealing time.
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    Journal of Biomedical Materials Research 8 (1974), S. 343-347 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: An investigation of metallic intramedullary fixation devices commonly used in orthopedic surgery revealed that the screw threaded portions of these devices were foci for corrosion and fatique fractures. After several design change proposals, a spherical head was developed which could be incorporated onto the intramedullary nails which would eliminate these problems. An extractor impactor was also developed to enable this new design concept to be utilized in surgery. The design and device are described and displayed.
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    Journal of Biomedical Materials Research 8 (1974), S. 385-390 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: This paper presents a review of 338 metallic endosteal oral implants of six designs that had been in situ for periods of up to seven years as observed by members of the Brookdale Group. Of the 338 impervious alloplastic endosteal implants studied, none but the endodontic endosteal implant demonstrated positive long range findings. It would appear that the eventual demise of endosteal implants is predictable on a basis of time.
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    Journal of Biomedical Materials Research 8 (1974), S. 409-425 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The detailed relation between primary, secondary, tertiary, and ultrastructure of collagen is presented. Electron micrographs of stained collagen are described in terms of specific peptide location. Data relating to the interaction of polysaccharides, notably chondroitin-6-sulfate, and proteoglycan and collagen are reviewed and a model for connective tissue developed. The relationship between such structure and that of calcified tissue is examined and some new data pertaining to the mechanism of calcification are introduced.
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    Journal of Biomedical Materials Research 8 (1974), S. 193-197 
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    Journal of Biomedical Materials Research 8 (1974), S. 261-269 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The human hip joint is capable of carrying loads exceeding several times body weight. The distribution of these loads over the load-bearing cartilage surfaces in the hip is of considerable interest in terms of studying the behavior of cartilage under various loading conditions. A modified Moore prosthesis has been designed which is capable of measuring in vivo the spatial and temporal pressure variations generated by the loads carried by the hip. The pressures as measured by this device will not only give a good indication of the pressure distributions that occur in the normal hip but will yield quantitative data on the pressures generated between the cartilage surface in the acetabulum and the ball of the prosthesis.The instrumented prosthesis consists of three main elements: a network of pressure transducers distributed over the surface of the ball, a multichannel telemetry device located inside the ball to transmit the information from the transducers to external receiving and recording equipment, and an electromagnetic power induction system which provides an external source of power for the telemetry device inside the prosthesis.A prototype has been fabricated which demonstrates the satisfactory functioning of the complete pressure measuring system.
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    Journal of Biomedical Materials Research 8 (1974), S. 331-341 
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    Notes: A conceptual model that relates the phenomenological stimuli responsible for bone remodeling has been developed as a preliminary exercise in a study designed to quantify Wolff's Law. In this regard, a set of thermodynamic and chemical kinetic equations have been formulated and their use in describing and predicting the formulation of crystalline hydroxypatite is presented.As a parallel activity, a macrocopic structural analysis of the bone-pylon interface has been conducted using a finite element representation and the results of this investigation are discussed as they relate to establishing a set of pylon design criteria.Finally, a modular, endoskeletal prosthetic system is described. The design of this appliance is based on the concept of total cosmesis and provides the present amputee with increased comfort and functionality as well as providing a system that can be effectively interfaced with a bone pylon when direct skeletal attachment (DSA) becomes a clinically accepted procedure.
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    Journal of Biomedical Materials Research 8 (1974), S. 1-1 
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    Notes: Conventional polyurethane prepolymers have been shown to adhere to living biological tissues. However, their setting is not sufficiently expedient to permit convenient applications in vivo. A prepolymer prepared from the highly reactive 6-chloro-2,4,5-trifluoro-1,3-phenylene diisocyanate, castor oil, and a trace of pyridine has afforded an adhesive which sets in about 2 min in vivo. The fast setting has resulted in poor adhesion on biological tissue. The bonding has been improved by the inclusion of tolylene diisocyanate in the composition without affecting the fast curing rate of the prepolymer. The dispersion of the adhesive and its cohesion after solidification have been adjusted by other minor additives. Preliminary evaluation on animals indicates that this adhesive is most useful as a hemostatic coating in hepatic lacerations.
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    Journal of Biomedical Materials Research 8 (1974), S. 81-86 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Journal of Biomedical Materials Research 8 (1974), S. 95-95 
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  • 89
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    Notes: Many types of materials are being used as biomaterials, and there is a continuing search for more and better materials for specific pur poses. In this investigation, a new method was employed in screening materials in an effort to cut costs, save time, and have a worthwhile indication of the prospect of a new material. Samples of twenty gauge wires of stainless steel 316, stainless steel 304, Titanium 40, Vitallium, and copper were introduced into leg or wing muscles of 18-day-old chick embryos.This was accomplished by opening the egg shell with a dental drill, implanting the material, and reclosing the shell. The chicks were allowed to hatch and were later sacrificed after eleven days, giving a total implant time of 14 days. This time period allowed for the acute inflammation that occurred during wound healing to subside. The sections were retrieved, embedded in epon 812, sectioned with a diamond saw, and histologically evaluated.Copper was used for the negative control and showed the greatest adverse tissue response. Titanium 40 showed almost no response and stainless steel 316 showed very little. Stainless steel 304 exhibited a somewhat greater response than the stainless steel 316. All of the materials except wrought Vitallium used in this experiment gave predicted results.
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    Journal of Biomedical Materials Research 8 (1974), S. 11-26 
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    Notes: Tissues from around surgical implants have been examined by optical microscopy and electron microscopy and by electron diffraction and x-ray spectrographic techniques. The presence of small alloy fragments and carbides worn from cobalt-chromium total joint replacements was confirmed. These foreign bodies had been phagocytosed by macrophages and there were no indications that the tissues were damaged by their presence. In 13 of 44 specimens there were granulomatous foci related apparently to the presence of numerous minute particles of unknown composition which had elicited vigorous macrophage reactions.In tissues near stainless steel joints too there were particles of the naked alloy taken up by macrophages and again the fibrous tissue appeared unaffected.Typically the tissues near to stainless steel implants are affected by cytosiderosis. It is deduced that the iron released by corrosion from stainless steel is processed by macrophages locally and there is formed a mixture of hydrated ferric oxides similar to hemosiderin. This may be looked upon as a detoxication mechanism. There is evidence that in some specimens the limit of tissue tolerance for stored iron has been exceeded locally with consequent pathological changes.Another common deposit around stainless steel implants occurs in large plaques. It attracts giant cells and there is evidence that it is fibrotic and cytotoxic.
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    Journal of Biomedical Materials Research 8 (1974), S. 77-83 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The adsorption, conformational changes, and desorption of biological molecules at foreign interfaces are effected by both kinetic and thermodynamic factors. The thermodynamic factors which drive the biomolecule/foreign interface system towards equilibrium include the enthalpy and entropy changes occurring during each step in the adsorption process. The principles governing interaction of proteins with nonwettable (nonpolar) and wettable (polar) foreign interfaces are discussed in terms of these thermodynamic parameters. Some examples to illustrate these arguments are presented are presented for plasma-protein interactions on Silastic and radiation-grafted hydrogel/Silastic interfaces.
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  • 93
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 8 (1974), S. 127-136 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Alloplastic implants in reconstructive surgery have many varied applications. The problem of extrusion in certain areas has not been totally resolved. Our intent was to design and develop a composite alloplastic implant which would be fixed to local tissues by fibrous ingrowth. Small amounts, less than 5% by weight, of a biodegradable substance with either Silicone type A or clear dental acrylic were used. Laboratory rats were implanted subcutaneously with sterile prostheses measuring 21 mm × 1 mm. The biodegradable portion consisted of presently available absorbable suture-polyglycolic acid, chromic catgut, and plain catgut in small particles. The implants were harvested at six weeks and three months and objectively evaluated for tissue fixation and fibrous reaction. In our model, the composite alloplastic prosthesis of chromic catgut and Silicone type A established superior fixation by fibrous ingrowth with a minimum of fibrous capsular thickness.
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  • 94
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 8 (1974), S. 311-317 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A new variant of the hinge type knee prosthesis has been developed in Sheffield, England. To date, the results of the early clinical trial in five patients are satisfactory, but it is recognized that the operation is highly speculative and continuation of the trial is being conducted with extreme caution. The main features are as follows.1The hinge is not provided with a mechanical stop to extension, the posterior ligament providing this check.2The contours of the femoral condyles are preseved.3Debris is collected inside the device.4Replacement of worn plastic components can be conducted without dismantling the knee.5There is a built-in resilience which is intended to protect the components and the bone-implant interface.
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  • 95
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 7 (1973), S. 353-367 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The transport of urea and other biologically interesting solutes in aqueous solution across poly(2-hydroxyethyl methacrylate) (p-HEMA) hydrogel membranes has been studied. The results show that p-HEMA membranes have a high permeability to urea due to a strong interaction between the polymer and urea, and, in addition, they are consistent with a pore flow model in which solute transport takes place through water-filled regions essentially unaffected by the surrounding polymer matrix. The results indicate that such p-HEMA membranes might be suitable for hemodialysis applications.
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  • 96
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 7 (1973), S. 405-418 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: This work represents a preliminary study of one case history of a silicone heart valve. The laboratory techniques employed have proven useful in characterizing the polymer before and after implantation. Before any model explaining ball variance can be proposed it must be determined whether the polymer loses its integrity because specific constituents in the body fluids interact with primary valence bonds in the polymer chains, or if the fluids simply cause swelling and plasticization of the crosslinked system and the damage is the result of mechanical work on the weaker polymer system. Detailed kinetic and thermodynamic studies are underway to answer these questions.The work summarized in this paper refers to the evaluation of only one specimen and should not be taken to mean that every silicone ball from a heart valve prosthesis will show this variance. The incidence of functionally variant silicone balls as reported to one manufacturer represents approximately 1.5% of the aortic and less than 0.05% of the mitral prostheses which have been supplied by this manufacturer. A small percent of valves of this type have the potential of becoming functionally variant and this is one failure mode which should be considered in the implantation of silicone ball valves.
    Additional Material: 7 Ill.
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  • 97
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 7 (1973), S. 481-484 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Splat cooling has been used for the preparation of dental alloy in the form of ribbons of 5-25 μm in thickness. The powdered alloy was produced by shaking the ribbons with a dental pestle in a mechanical amalgamator. One minute shaking produced a powder all of which passed a standard 400 mesh sieve. Only phases expected at room temperature have been produced thus far.
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  • 98
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 7 (1973) 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
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  • 99
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Male mongrel dogs were divided into two groups and placed in urine collection cages for 24-hr urine samples. One group was implanted with sterile radiopaque polyethylene catheter and stainless steel guide wire fragments in the venous vasculature via an incision in the left femoral vein and the remaining group in the arterial vasculature via the left femoral artery. The catheter fragments, made radiopaque by an admixture of 25% lead oxide and 75% polyethylene, were located by roentgenograms and along with the guide wire fragments removed at necropsy 18-46 weeks following implantation. Gross and microscopic tissue lesions consisted of fibrous tissue tubes and slings which completely enclosed and anchored the fragments and intimal hyperplasia with fibrous tissue organization of thrombi, respectively. Tissue staining techniques for lead, catheter fragment weights, blood lead levels, and urine lead content all revealed no evidence of lead loss from the catheter fragment implants.
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  • 100
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 7 (1973), S. 193-200 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The rate of diffusion of pyrimethamine, a pyrimidine-based antimalarial drug, from silicone rubber is compared to the diffusion of this drug from a flexible epoxy. Specific amounts of drug were mixed into the epoxy resin prior to the addition of an aliphatic diamine curing agent in the reparation of the epoxy-drug capsules and into the silicone rubber prior to vulcanization with stannous octoate in the preparation of silicone drug capsules. These capsules, in the form of discs, were separately immersed in water which was replenished at regular time intervals. The amount of drug released was determined spectrophotometrically (λ max = 275 mμ). Silicone rubber discs with 20 mg of drug incorporated/disc showed a much higher initial release rate than epoxy discs with an equivalent amount of drug incorporated. The rate of drug release is shown to be a nonlinear function of the amount of drug initially incorporated. The amine functional groups on pyrimethamine, and the possibility of its participation in the curing of the epoxy is noted. In silicone rubber, such interaction is not expected. The addition of a silica filler to the epoxy drug mixture is associated with greater uniformity in the observed drug release rates of capsules made from the same batch of polymer drug mixture. The Shore A durometer hardness of these drug capsules are 30 and 70 for silicone rubber and epoxy, respectively.
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