bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies of the stability and toxicity of zinc polyacrylate (polycarboxylate) cements (PAZ)
Authors: Peters Walter J. , Jackson Robert W. , Smith Dennis C. 
Published: December 2004

AbstractZinc 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.
Experimental analysis of ceramic‐tissue interactions. A morphologic, fluoroescenseoptic, and radiographic study on dense alumina oxide ceramic in various animals
Authors: Griss Peter , Krempien Burkhard , von Andrian‐Werburg Hanns Frhr. , Heimke Gunther , Fleiner Roland , Diehm Theo 
Published: December 2004

AbstractTwo types of dense Al2O3 ceramics (99.6% purity, 96% purity) were tested in the following fields of interest.
Wear resistibility using a pin and disk method under distilled water and human synovial fluid. Both types showed minimal initial corpuscular wear.
Biocompatibility 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.
Under 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.
A 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.
The foreign body reaction—an experimental protocol
Authors: Coleman D. L. , King R. N. , Andrade J. D. 
Published: December 2004

AbstractA 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.
A comparison of soft tissue reaction to silastic and absorbable suture material
Authors: Toranto I. Richard , Salyer Kenneth E. , Nickell William B. 
Published: December 2004

AbstractAlloplastic 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.
Calcium‐phosphate magnesium‐aluminate osteoceramics
Authors: McGee Thomas D. , Wood Jack L. 
Published: December 2004

AbstractCeramic 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.
Establishment of a theoretical base‐design of a lower extremity prosthesis
Authors: Newell P. H. , Krouskop T. A. , Jendrucko R. J. , Chakraborty B. K. 
Published: December 2004

AbstractA 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.
Materials in maxillofacial prosthetics
Authors: Chalian V. A. , Phillips R. W. 
Published: December 2004

AbstractMaxillofacial 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.
Molecular aspects of calcified tissue
Authors: Walton A. G. 
Published: December 2004

AbstractThe 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.
The load‐deformation characteristics of connective tissues
Authors: Kenedi R. M. 
Published: December 2004

AbstractFollowing 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.
The role of biomechanics in oral implantology
Authors: Knoell A. C. , Grenoble D. E. 
Published: December 2004

AbstractThis 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.
A thromboresistant surface by enzyme immobilization
Authors: Nguyen An‐Lac , Wilkes Garth L. 
Published: December 2004

AbstractA 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.
Porous Vitallium in implant surgery
Authors: Cameron H. U. , Pilliar R. M. , Macnab I. 
Published: December 2004

AbstractThe 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.
Study of pig valve heterografts by X‐ray diffraction
Authors: Huc A. , Planche Cl. , Weiss M. , Mannschott Ph. , Chapin F. , Chabrand D. 
Published: December 2004

AbstractThe study of collagen fibers by X‐ray diffraction, utilizing semiquantitative indices for appraisal of “structuration” and “orientation” was applied to 30 aortic valve grafts. These grafts, of pig origin, were studied in the fresh state, after tanning with aldehydes, and after having been implanted in patients for at least 18 months. It was shown that the collagen fibers are preferentially orientated parallel to the transverse axis of the valve cusps, and that this arrangement, enhanced by tanning, had a tendency to disappear in the post‐implantation samples. The structuration index which concerns the fibril network was also augmented by tanning, and was found a little high or slightly diminished in post‐implantation cusps. Evidence for a new compound, probably fibrin, was found in the diffraction patterns of implanted cusps, but crystallized calcium was noticeably absent.
The development of an abrasion testing machine for dental materials
Authors: Harrison Alan , Lewis T. T. 
Published: December 2004

AbstractWear testing should be an important part of the investigations into the physical and mechanical properties of some dental materials. It has, however, largely been ignored because of conflicting and unreproducible results. It was decided, therefore, to review the work done by other researchers and to examine the human masticatory cycle, and then present new parameters to design and construct a new dental abrasion testing machine. This new machine is described in detail and its capabilities briefly illustrated.
The influence of compositional variations on bone ingrowth of implanted porous calcium aluminate ceramics
Authors: Graves G. A. , Noyes F. R. , Villanueva A. R. 
Published: December 2004

AbstractSixteen ceramic specimens were implanted in the femur of mature rhesus monkeys. The specimens consisted of four groups of a basic calcium aluminate composition with additions of 5, 10, 15 and 20 wt% phosphorous pentoxide (P2O5). The increasing amounts of P2O5 caused variations in the resorption rate, microstructure and surface characteristics of the implant. The influence of these variables on bone and tissue growth within and about the implant was investigated.After sacrifice the ceramic‐bone specimens were studied by a tetracycline‐based histological analysis, scanning electron microscopy and energy dispersive analysis.The results indicate an increase in mesenchymal cell proliferation, fibrous and bone tissue formation at the ceramic tissue interface and within the implant with increasing concentrations of P2O5.The results obtained from the study did not furnish sufficient evidence to differentiate between the direct chemical influence the increasing P2O5 had on osseous tissue formation or the indirect influence that may have resulted from its effect on the ceramic microstructure and morphology.
Fractography of poly(methyl methacrylates)
Authors: Kusy R. P. , Turner D. T. 
Published: December 2004

AbstractFor convenience in clinical manipulation, it is the practice to fabricate PMMA prostheses from mixtures of powder and monomer. When the monomer is subsequently polymerized an unusual 2‐phase polymeric material results in which grains of PMMA are dispersed in a matrix of the same polymer.The mechanical properties of the 2‐phase materials are inferior in certain respects relative to 1‐phase polymers.The purpose of the present work is to evaluate the failure of 2‐phase materials by microscopical examination of their fracture surfaces. A granular microstructure was clearly distinguishable and a distinction made between materials which fail exclusively by transgranular fracture and others which additionally exhibit intergranular fracture.In order to interpret markings observed on the fracture surfaces of the complex 2‐phase systems a study was made of the influence of molecular weight on the fractography of 1‐phase PMMA. Molecular weight was reduced by degradation of samples by exposure to γ‐rays. The spacing of periodic rib markings on fracture surfaces was found to decrease with molecular weight and this relationship used to provide an estimate of the molecular weight of polymer in the matrix of 2‐phase materials.
Porous, heat cured poly (methyl methacrylate) for dental implants
Authors: Gettleman Lawrence , Nathanson Dan , Myerson Richard L. , Hodosh Milton 
Published: December 2004

AbstractThe use of polyl (methyl methacrylate) for tooth replica implants, as developed by Hodosh, is described as to indications, ingredients, and fabrication technique. Laboratory testing of this material for mechanical and thermal expansion properties, and porosity content were determined as a function of foaming agent and anorganic bone particle content.
Growth kinetics of γ2 crystals on mercury‐plated Ag3Sn
Authors: Okabe T. , Hines A. L. , Hochman R. F. , Sims L. O. 
Published: December 2004

AbstractPrevious work has shown that needles of γ2 crystals form when mercury is plated on the surface of an Ag3Sn specimen. In the present study, the growth kinetics of γ2 needles were investigated from room temperature to 50°C for varying amounts of plated mercury. Straight‐line relationships between crystal length and the square root of the time of growth showed that the growth rate is diffusion controlled. The growth rate increased with temperature up to 40°C but decreased at higher temperatures. Further, as the temperature was increased, fewer γ2 crystals formed and their growth length decreased. This demonstrates that a number of competing factors are involved in the growth process at high temperatures.
Deposition of blood cells on collagen and cuprophane membranes
Authors: Schwartz A. , Stenzel K. H. , Kohno I. , Ast D. , Miyata T. , Rubin A. L. 
Published: December 2004

AbstractDogs were dialyzed with collagen and cuprophane membranes, human renal failure patients were dialyzed with cuprophane membranes, and samples of the membranes were observed by scanning electron microscopy at different time periods. Fixation was done in glutaraldehyde and cacodylate buffer, and samples were dried at the critical point. All cellular elements were well preserved and appeared viable. Cuprophane adsorbed platelets almost selectively in dog dialyses, whereas collagen adsorbed a smaller number and more heterogeneous group of cells. In contrast to these findings, when cuprophane was used in clinical dialyses, the cell population was predominantly polymorphonuclear leukocytes.
The interactions of thrombin with borosilicate glass surfaces
Authors: Waugh David F. , Anthony Linda J. , Ng Helen 
Published: December 2004

AbstractBorosilicate glass (G) and commercial poly(methyl methacrylate) (PMM) surfaces were examined at pH 7, monovalent ionic strength 0.14 and 22°C. Thrombin concentrations ranged from 6 × 10−9 to 5.2 × 10−8M. Decreases in thrombin concentration in 10 ml vessels were determined by clotting time assay. Adsorption to PMM vessels is small. These were examined to establish the validity of the method. For G‐vessels, the terminations of initial rapid decreases, associated with adsorption equilibrium, are accounted for mainly by an average isotherm having an association constant of 1.8 × 107 1./mol. Adsorption equilibrium is accompanied by a slower rate of decrease consistent with the surface denaturation of 2.5%/min of adsorbed molecules.Molecules remaining adsorbed to the surfaces of 1 mm i.d. G‐capillaries were examined using the sequence of thrombin adsorption, buffer washing for times tw, removal of buffer and introduction of a fibringen aliquot for determination of effective surface thrombin concentration by a capillary clotting time. Most adsorbed molecules (<90%) essentially desorb within tw = 2 min, a second class (>8%) desorb in tw ∼30 min, and members of additional classes are still present after tw = 1440 min. For all of the properties examined, there is a small variance between vessels taken at the same time from the same batch, and a larger variance between groups of vessels taken at different times from the same batch or from different batches.
Corrosion of surface defects in fine wires
Authors: Rentler R. M. , Greene N. D. 
Published: December 2004

AbstractDefects were observed on the surfaces of various fine diameter wires commonly used in biomedical applications. These surface irregularities were viewed at high magnifications using a scanning electron microscope which has a much greater depth of field than normal light microscopy. Defects include scratches, pits, and crevices, which are the result of commercial wire drawing practices. Corrosion test results show that imperfections can serve as sites for localized corrosion attack which could lead to premature failures.
Hydrophilized polyethylene catheters
Authors: Kaganov A. L. , Štamberg J. , Synek P. 
Published: December 2004

AbstractComplications arising in the application of polyethylene catheters in surgery may be reduced by their surface hydrophilization. This study describes a combination of chemical transformation and coating with a hydrophilic gel. Modified catheters were tolerated well by the patients and in contrast with the original catheters, they did not lead to the formation of thrombi or phlebitis.
Electrical stimulation of bone growth into porous Al2O3
Authors: Weinstein Allan M. , Kalwitter Jerome J. , Cleveland Thomas W. , Amoss Donald C. 
Published: December 2004

AbstractPorous, cylindrical, high alumina, ceramic structures were fabricated for implantation in the superior third of canine femoral medullary canals. Implant durations of one, two, four, and eight weeks using three animals per time period were studied. A constant current (10 μA) power supply was used to attempt to stimulate bone growth into the porous ceramic structures. Osseous tissue ingrowth was evaluated using a mechanical push‐out test, microradiography, and histological thin sectioning. The interfacial shear strength and tissue microstructure was studied as a function of implant residence site and implant residence time.The results indicate that initially the proximal implants have a higher interfacial shear strength, however, after eight weeks of implantation the distal implants have a shear strength about twice that of the proximal implants. This trend is observed for both the electrically stimulated and nonstimulated specimens. The 10 μA current level used in this investigation was found to have a small but significant effect on shear strength increasing it at implantation times of less than eight weeks.
A comparative study of the early vascularization of porous carbon and bone as a graft
Authors: Lozano Alexander J. , Cestero Herman J. , Salyer Kenneth E. 
Published: December 2004

AbstractUtilizing rats as a model, it was demonstrated that both iliac crest bone and porous carbon disks, when used as onlay grafts, become vascularized as early as 3 days. There is no significant difference between the two. The soft tissues, periosteum, and recipient bone are all capable of supplying vascularization to the graft or implant.
An in vitro investigation of the anodic polarization and capacitance behavior of 316‐L stainless steel
Authors: Sutow Elliott J. , Pollack Solomon R. , Korostoff Edward 
Published: December 2004

AbstractDeterminations were made of how the corrosion‐resistant properties of the passive film on 316‐L stainless steel are influenced by the material's mechanical and surface states, and the variable pH and PO2 conditions of the interstitial fluid.Cold‐rolled and annealed specimens were surface‐prepared, commercially and in the laboratory, respectively, as if for orthopedic implantation. Passive film behavior was studied by the anodic polarization and pulse‐ potentiostatic capacitance methods. The pH and PO2 of the Ringer's test solution were varied to include interstitial fluid values occurring postoperatively and onto recovery.The anodic polarization behavior of all specimens was found to be pH‐ and PO2‐independent. Breakdown potentials of annealed specimens were 800–950 mV (SCE), in contrast to previously reported values of approximately 350 mV. This substantial increase is related to the influence of surface preparation and, in particular, to the optimization of electropolishing time which acts to produce a microscopically smooth surface, free of debris and disarrayed material. Capacitance behavior of annealed material for potentials > 400 mV was consistent with a model involving the entry of chloride and metal ions (mostly Fe) into the passive film. This entry is related to the onset of pitting.
Biochemical response to Dacron vascular prosthesis
Authors: Noishiki Yasuharu 
Published: December 2004

AbstractDacron vascular prostheses were examined under both light and electron microscopes from 1 to 1184 days after implantation in the thoracic aorta of 96 dogs. Each Dacron fiber of the implanted prostheses was found to be covered with a single layer, which closely resembled the outer half leaflet of plasma membrane. The control experiment in vitro revealed that when untreated Dacron fibers were dipped into a solution of lecithin, the fibers became covered with monomolecular leaflets of lecithin micelles. On the basis of the in vivo and in vitro findings, it was suggested that the implanted Dacron fibers of vascular prosthesis were covered at an early stage with a monomolecular micelle layer of phospholipid or phospholipoproteins originating from the living body, and thus became adapted to the living body.