bluuebunny/crossref_metadata_2025_split huggingface dataset:
The restoration of articular surfaces overlying replamineform porous biomaterials
Authors: Chiroff Richard T. , White Rodney A. , White E. W. , Weber J. N. , Roy D. 
Published: December 2004

AbstractReplamineform porous implants (4 mm × 4 mm diameter) were placed into full‐thickness cartilage and bone defects of the weight‐bearing surface of the lateral femoral condyles of adult male white rabbits. These were analyzed at 1 day, 1 week, 6 weeks, 3 months, and 6 months for (1) ingrowth of tissue within the implants and (2) restoration of the articular surface overlying them. Appropriate unfilled, but similar, control defects were also studied.Mineralized bone was seen within the substance of both the TiO2 and hydroxyapatite implants at 1 week; this extremely rapid response was present in every specimen studied and was not seen with αAl2O3 or control animals. With the passage of time, maturation of this bone ingrowth occurred so that by 3 months, they were all incorportated into the surrounding bone.Only the hydroxyapatite implants showed consistent regenerative healing of hyaline articular cartilage from the margins of the defects with the passage of time; this occurred whenever the subchondral bone adjacent to the defect proliferated in a “creeping” fashion over the articular aspect of the implant, and the undamaged cartilage then followed it. Fibrocartilage, and not hyaline cartilage, formed the articular surface over the TiO2 and αAl2O3 implants and in the controls.
Evaluation of a biodegradable ceramic
Authors: Cameron H. U. , Macnab I. , Pilliar R. M. 
Published: December 2004

AbstractAn evaluation of a porous biodegradable ceramic, tricalcium phosphate, has been carried out. When implanted in cancellous bone, it is rapidly infiltrated with bone and slowly resorbed. When held rigidly against raw, bleeding, cortical bone, again rapid bone ingrowth occurs.The material does not give rise to any untoward tissue reaction, nor does it cause any systemic reaction. It can therefore be concluded that the material is safe for use in clinical practice, and can be used in specific instances either to replace or to supplement bone grafting.
Effect of fluoride on the stabilization of metal implants in the femur of rabbits
Authors: Laor Mark , Gedalia Itzhak , Simkin Ariel , Yosipovitch Zvi , Arcan Mircea 
Published: December 2004

AbstractA single application of fluoride to the epiphysis of the femur induced accelerated bone formation. The additional bone gave rise to a stability effect on the implant inserted in the femur as expressed by an increased dislodgement force required.
Analysis of bioglass fixation of hip prostheses
Authors: Hench L. L. , Pantano C. G. , Buscemi P. J. , Greenspan D. C. 
Published: December 2004

AbstractThe analysis of the bonding interface between hip prostheses and bone after functional use in animals was carried out. Scanning electron microscopy (SEM) with energy dispersive analysis (EDX), and Auger electron spectroscopy were used to evaluate the bonding interface. Various methods of postsacrifice sample preparation were used to evaluate the effect of such different methods on the analysis of the bonding interface. Comparison of the results with several rat tibia implant experiments is also presented.
Influence of the heat treatment of commercial amalgam alloys on the phase composition of the alloys and the creep of the resulting amalgams
Authors: Vrijhoef M. M. A. , Jensen S. J. 
Published: December 2004

AbstractThe influence of heat treatment of dental alloys at several temperatures on the phases present in the alloy and the creep of the resulting amalgam as well as the correlation between phase changes and the creep was investigated. A dependence of the creep on the temperature of the heat treatment of the alloy was established. Substantial phase changes were observed after the different heat treatments. No correlation was detected between the creep rate and the changes in phases present in the dental alloys. A thermodynamically oriented explanation of the relation between the creep of the amalgam and the state of (non‐) equilibrium of the corresponding amalgam alloy was proposed and discussed.
Studies on dental self‐curing resins. XV. Application of nitrene to reactive adhesive with a tooth
Authors: Nakabayashi Nobuo , Hayata Shigeru , Masuhara Eiichi 
Published: December 2004

AbstractEffectiveness of p‐azidobenzoyloxyethyl methacrylate on the adhesion of a tooth was studied. This methacrylate, dissolved in suitable monomer solvents such as 2‐hydroxyethyl methacrylate, was painted on ivory‐ or acid‐etched enamel and the surface was irradiated by ultraviolet light. Photolysis of the azide produced a nitrene which was reactive with polypeptides in the tooth. As the treated surface must have affinity with methyl methacrylate (MMA) and poly (methyl methacrylate) (PMMA), it was joined with a PMMA bar by the self‐curing resin. The adhesive strength was 100 kg/cm2 with ivory or 65 kg/cm2 with enamel. Graft copolymerization of methyl methacrylate onto collagen may take place by the nitrene prepared in situ by photolysis of the azide. Subject to satisfactory biologic evaluation, this coupler may be useful in the development of adhesive dental filling materials and fissure sealants.
Biodegradability and tissue reaction of random copolymers of L‐leucine, L‐aspartic acid, and L‐aspartic acid esters
Authors: Marck K. W. , Wildevuur Ch. R. H. , Sederel W. L. , Bantjes A. , Feijen J. 
Published: December 2004

AbstractA series of copoly(α‐amino acids) with varying percentages of hydrophilic (l‐aspartic acid) and hydrophobic monomers (l‐leucine, β‐methyl‐l‐aspartate, and β‐benzyl‐l‐aspartate) were implanted subcutaneously in rats and the macroscopic degradation behavior was studied. Three groups of materials (A, B, C) with different ranges of hydrophilicity were distinguished: A) hydrophobic materials showed no degradation after 12 weeks; B) more hydrophilic materials revealed a gradual reduction in size of the samples, but were still present after 12 weeks; and C) hydrophilic copolymers disappeared within 24 hr.The tissue reactions caused by the materials of group A resembled that of silicone rubber, whereas those of group B showed a more cellular reaction.
Development of semicrystalline poly(vinyl alcohol) hydrogels for biomedical applications
Authors: Peppas Nikolaos A. , Merrill Edward W. 
Published: December 2004

AbstractSwollen crosslinked poly(vinyl alcohol) (PVA) networks were developed and tested as potential biomaterials. They were prepared by electron‐beam irradiation of aqueous PVA solutions at various temperatures and doses of irradiation. These materials were characterized by low mechanical properties and especially by low elongation at break and ultimate tensile strength. Reinforcement was achieved by a two‐stage dehydration‐annealing process, introducing crystallites in the polymeric network. Improved mechanical properties were achieved due to the presence of this crystalline PVA phase. Due to their structure, these hydrogels are proposed to be used as biomembranes for selective transport of macromolecules and as biomaterials for synthetic articular cartilage applications. Surface heparinization was accomplished by reacting heparin to the hydroxyl groups of the PVA surface, through covalent acetal bridges.
The strength of LTI carbon dental implants
Authors: Shim Hong S. 
Published: December 2004

AbstractIn vitro mechanical tests have been performed on a variety of LTI pyrolytic carbon blade‐type dental implants, and the test results have been analyzed using an analytical model. Tensile stresses at fracture were calculated to be about 5 × 104 psi and 8 × 103 psi in the LTI carbon coating and the graphite substrate, respectively. These values are close to their respective fracture strengths. The fracture loads predicted by the model are in good agreement with data obtained from the mechanical tests and are higher than forces expected in mastication.
Porosity in the base metal removable partial denture casting alloys relative to observable metallographic features
Authors: Lewis Arthur J. 
Published: December 2004

AbstractA series of tensile test pieces of the dimensions stated in the American Dental Association Specification No. 14 were produced using both nickel‐base and cobalt‐base removable partial denture casting alloys. Normal dental casting techniques were employed. Appropriate sections from each specimen were sectioned to half of their original thicknesses, embedded in heat‐ and pressure‐cured conducting mounts, and polished for metallurgical examination. A double electrolytic etching technique was used, employing serially two solutions, in order to maximize the amount of metallographic detail visible. The method proved particularly valuable in the case of the nickel‐base alloy as it indicated the presence of considerable interdendritic segregation. The incidence of porosity was evaluated throughout all sections of the specimens and, although found to be especially prevalent in those regions where gross shrinkage effects might be expected to occur, it was also shown to have a diffuse intergranular and interdendritic distribution.
Tolerance of mouse macrophages in vitro to barium sulfate used in orthopedic bone cement
Authors: Rae T. 
Published: December 2004

AbstractBarium sulfate, used as a radio‐opaque marker in some orthopedic bone cements, has been shown to escape into the surrounding tissues. This may present a potential hazard. In particular, phagocytic cells may be exposed to relatively high internal levels of barium once the particles have been phagocytosed.Mouse peritoneal macrophages exposed to barium sulfate for periods up to 144 hr showed a marked cytoplasmic vacuolization from which they recovered only partially. Barium sulfate did not appear to damage the cell membrane as judged by lactic dehydrogenase release.In the relatively low doses and with the periods of exposure described here, barium sulfate does not appear to present a serious toxic hazard in the short term. It is possible, however, that longer exposures and larger doses may result in the death of phagocytic cells which have ingested barium sulfate.
Presence of adipose fat as a criterion of implant compatibility
Authors: Kaminski Edward J. , Shenk Michael W. , Oglesby Richard J. 
Published: December 2004

AbstractAn analysis of the tissue sections from previous implant studies was performed to define additional criteria which could be considered in determinations of biocompatibility of implant materials.Adult albino rabbits were implanted with biomaterials in the sacrospinalis muscle for periods of 2, 6, 18, and 54 weeks. Fourteen different implant materials were used in this study. The tissues were examined histologically for the appearance of adipose fat cells within the membrane surrounding the implant as an important criterion of tissues implant compatibility. The results were compared with other previously used criteria in judging biocompatibility of implant materials. For the most compatible nonreactive materials, adipose tissue formation within the pseudomembrane began at 6 weeks and was quite extensive at 54 weeks. The reactive materials studied by us did not exhibit this phenomenon.
A percutaneous implant using a porous metal surface coating for adhesion to bone and a velour covering for soft tissue attachment: Results of trials in pigs
Authors: Fernie G. R. , Kostuik J. P. , Lobb R. J. , Pilliar R. M. , Wong E. , Binnington A. G. 
Published: December 2004

AbstractA percutaneous implant for the attachment of an artificial limb has been designed and tested in 14 pigs. Firm fixation to beone was achieved with the porous‐surface layered metal intramedullary stem design in some cases. Dacron velour was used at the soft tissue interface. Evidence of soft tissue ingrowth was seen. However, the velour was unable to maintain adequate epithelial adhesion to form an anatomical seal and a barrier to bacteria.
An approach to the soft tissue/synthetic material interface
Authors: Bagnall Robert David 
Published: December 2004

AbstractIt is argued that chemical modification of soft tissue implants in the hope of obtaining an associated tissue response is unlikely to succeed as a method for studying the fundamentals of implant/tissue interactions. An alternative approach is proposed which places greater emphasis on the interfacial interactions (such as protein adsorption) which occur after implantation, in a manner paralleling current advances in knowledge of the blood/material interface. From simple arguments, it is proposed that the observed similarities in soft tissue response of hydrophobic materials may result from irreversible protein adsorption, and that if unusual tissue responses are possible they are likely to be found only with hydrophilic implants. The possibility of a critical hydrophilic/hydrophobic character which an implant must possess for essentially irreversible protein adsorption is also discussed.
Biocompatibility testing of polymers: In vitro studies with in vivo correlation
Authors: Rice Robert M. , Hegyeli Andrew F. , Gourlay Stuart J. , Wade Clarence W. R. , Dillon James G. , Jaffe Howard , Kulkarni R. K. 
Published: December 2004

AbstractAn in vitro method has been developed for screening of candidate biomaterials in an early phase of their development. The test is based on L‐929 mouse fibroblast cultures and their response to powdered polymer samples. It applies microscopic observation for the detection of morphological changes, uses dye exclusion testing for cell viability determination, and utilizes estimation of population doublings as an end point. The test is shown to be reliable and reproducible and is compared to in vivo implantation studies in rats, previously reported.
Protein sorption on polymer surfaces measured by fluorescence labels
Authors: Brynda E. , Drobník J. , Vacík J. , Kálal J. 
Published: December 2004

AbstractFluorescence labeling can be used in studying protein sorption on various surfaces with a sensitivity of about 10−8 g/cm2, commensurate with radioactive labeling. Fluorescamine proved to be the most suitable compound for studying protein sorption on hydrophilic gels, because, unlike fluoresceine isothiocyanate and dansylchloride, free fluorochrome does not interfere with measurements. Sorption properties of labeled serum albumin were tested on poly(2‐hydroxyethyl methacrylate), on the copolymer of 2‐hydroxyethyl methacrylate with methyl methacrylate, and on polyethylene. Labeling does not cause aggregation of the protein, but, as expected, it shifts and somewhat broadens its electrophoretic band while at the same time slightly raising its affinity toward hydrophobic surfaces.
Experimental bladder substitution using a biodegradable graft of natural tissue
Authors: Novick Andrew C. , Straffon Ralph A. , Koshino I. , Banowsky Lynn H. , Levin Howard , Kambic Helen , Nosé Y. 
Published: December 2004

AbstractA controlled canine experimental study has been performed to test the application of a biodegradeable graft to vesical augmentation. The graft, after providing initial bladder enlargement, is progressively reabsorbed while serving as a foundation for the regeneration and healing of the layers of the bladder remnant. Follow‐up studies at 1 year revealed no urinary infection, calculi, extravasation of urine, or rejection of the material. Normal bladder capacities were maintained throughout the study and the reconstructed bladders functioned normally. The biodegradable graft was equally successful when applied either to a histologically normal bladder remnant, or to a pathological bladder of intramural fibrosis. These results suggest that this material may be well suited to clinical bladder substitution in humans.
Effect of simplex liquid methyl methacrylate monomer on cells
Authors: Welch Ardyce B. 
Published: December 2004

AbstractThe effect of methyl methacrylate monomer used for polymerization of surgical bone cement on phagocytosis, blood cells, tissue cells in culture, and bacteria was investigated. A concentration of 0.5% monomer reduced the ability of macrophages in vitro to phagocytize cultures of Staphylococcus epidermidis effectively. In vivo, 0.03 ml injected into mice also reduced the capacity of peritoneal macrophages to phagocytize bacteria. Extent of cellular damage to blood cells varied with concentration of monomer used and time of contact but, in general, 0.5% was sufficient to alter morphology and viability of blood cells and tissue cells in culture. Polymorphonuclear neutrophils sustained more damage than other types of blood cells. Only minor alterations were detected from cooled, polymerized cement. These studies support the concept that the monomer, as well as mechanical and thermal factors, may be responsible for some of the tissue changes seen at the site of implant of bone cement following total joint arthroplastic surgery.
Surface chemical analysis of avcothane and biomer by Fourier transform IR internal reflection spectroscopy
Authors: Sung C. S. Paik , Hu C. B. , Merrill E. W. , Salzman E. W. 
Published: December 2004

AbstractDuring the solvent casting process, one side of the polymer film is exposed to air while the other side is in contact with a substrate, used as a mold. We have studied the effect of this difference in exposure during casting on the chemical composition of two types of segmented polyurethane,5 BiomerBiomert™, Ethicon Corp., Somerville, N.J.
and Avcothane,Avcothanetm™, Avco‐Everett Co., Everett, Mass.
by using Fourier transform IR internal reflection spectroscopy. Also, a depth‐composition profile was obtained by placing a thin barrier film between the reflection plate and the polymer film.In Avcothane, the air side, which is the blood‐contact side, contains a greater amount of the soft segment than the substrate side, and this is more pronounced in the layer closer to the surface. The anisotropy in composition is more drastic when the silicone content is compared. In a layer about 1.5 μ thick, one can detect a greater amount of silicone in the substrate side than in the air side. However, when one averages the concentration in a layer of about 0.8 μ, the trend is reversed; i.e., the greater amount of silicone is now present in the air side than in the substrate side. In Biomer films, the anisotropy in chemical composition is less pronounced. Only a modest increase in the relative content of the soft segment/hard segment is observed in the air side when a depth‐composition profile is obtained.
Adhesion of synthetic organic polymer to soft tissue. III. Effect of some monofunctional compounds
Authors: Wang P. Y. , Llewellyn‐Thomas E. 
Published: December 2004

AbstractPrevious work in this series has shown that some aromatic and n‐alkyl isocynates can significantly improve the adhesion of a fast‐setting polyurethane prepolymer to internal tissue. In the present study, several acyl or aroyl anhydrides, chlorides, and a triaryl chloroalkane have been found to effect various degrees of improvement in the adhesion of fast‐setting prepolymer to tissue. To determine the influence of minor structural changes on adhesion, the isomers of methyl phenyl isocynate and chlorobenzoyl chloride were investigated. The isomers were found to give the same extent of improvement in adhesion of the prepolymer as the parent compound without the methyl or chloro substituents. Among all the reactive monofunctional compounds studied, benzoyl chloride and its chlorobenzoyl derivatives are the most effective. When primed on tissue or admixed as little as a 3% additive in some polymer preparations, these aroyl chlorides can promote the adhesion of many ordinary adhesives to internal tissue. The effectiveness is attributed to the modification of hydrophilic tissue surface by the hydrophobic benzoyl group attached to tissue after reaction. The prosthetic benzoyl group makes the tissue/polymer interface more compatible and the compatibility results in good adhesion.
Antibiotics in acrylic bone cement. In vivo studies
Authors: Welch A. B. 
Published: December 2004

AbstractIn vivo experiments were performed to study elution rates of antibiotics combined with Surgical implex bone cement and efficacy in controlling bacterial infections. Cylinders of bone cement were implanted in animals and at the same time the surgical areas were infected with large numbers of bacteria. Gentamicin and Keflin were eluted from the cylinders in sufficient quantities to completely eliminate or markedly reduce the number of bacteria recovered from infected areas. Animals were also treated with an anti‐inflammatory drug, hydrocortisone, prior to implantation of cylinders and infection. The antibiotics in the bone cement effectively destroyed the bacteria in these animals with impaired inflammatory responses as compared with control animals.
Corrosion behavior of structural phases in high copper dental amalgam
Authors: Marek M. , Okabe T. 
Published: December 2004

AbstractThe effects of crevice corrosion on the major structural phases of a high copper dental amalgam were studied in vitro. Three kinds of samples were used: (1) amalgam prepared from a high copper, single composition alloy, (2) annealed ingots of the Ag3Sn and Cu3Sn phases, and (3) high copper, single composition alloy tablets electroplated with mercury. Specimens were examined in a scanning electron microscope before and after the exposures to a corrosion environment.The Ag3Sn and Cu3Sn phases were least affected by corrosion. The Ag‐Hg‐Sn phase (γ1) slowly deteriorated, but the attack was nonuniform. The Cu6Sn5 phase exhibited good corrosion resistance, better than that of the γ1 phase. Particles of a tin rich phase of uncertain origin were observed on some of the samples after long exposures.
A study of the normal range of strain, strain rate, and stiffness of tendon
Authors: Herrick W. C. , Kingsbury H. B. , Lou D. Y. S. 
Published: December 2004

AbstractThis paper describes the result of an investigation of strains and strain rates which normally occur in the tendons of the equine foreleg and presents stress‐strain curves and moduli for the tendons at these rates.It has previously been demonstrated that resistance to flexion of the joints of the distal part of the equine foreleg is provided by a passive system of tendons and ligaments. It is therefore possible, using a large displacement, high‐rate testing machine, to duplicate in the laboratory the strain rates and forces which are normally produced in the tendons of the foreleg of the running horse.To carry out tendon tests, legs were mounted in the test machine. The superficial flexor tendon was exposed and fitted with an extensometer and a buckle‐type force transducer. Stress‐strain curves were obtained for 13 tendons.It is shown that strains to 12% and strain rates to 200%/sec occur normally in the superficial flexor tendon. Stress strain curves and tangent modulus are presented for strains from 0 to 10% at rates from 5 to 100%/sec. Tendon modulus is found to be essentially rate independent in this range.