bluuebunny/crossref_metadata_2025_split huggingface dataset:
Changes in nonosseous tissue adjacent to titanium implants
Authors: Meachim G. , Williams D. F. 
Published: December 2004

AbstractA combined histological, metallurgical, and clinical study has been made in 19 instances where a surgical operation had been performed to remove a titanium implant used in the treatment of disease or trauma in man. All the implants were static devices such as pins, plates and rods. Histological examination of nonosseous tissue excised from adjacent to the implant was supplemented by estimation of its titanium content by neutron activation analysis.The results indicate that in some patients titanium can be liberated into tissue adjacent to titanium implants. The phenomenon can occur in the absence of corrosion or fracture of the implant, and is unrelated to the possible liberation of wear particles from an artificial articular surface. There is variation from individual to individual in the amount, if any, of titanium released. In the case of those implants showing titanium release, the results suggest that local release of the metal, or its subsequent accumulation in the tissue, is a patchy process at the implant site. The histological features of the local reaction of nonosseous tissue to titanium release are described. No conclusions have been drawn concerning possible effects on the osteogenic response to the insertion of the implants and on the overall state of the bone at the time of their removal. From study of the clinical records it is apparent that considerable caution is needed before concluding that release of titanium can cause clinically significant local effects. Although such effects may have occurred in a minority of patients, this possibility is by no means proven. A distinction must be drawn between a “metal reaction” in the histological sense and a “metal reaction” in the clinical sense.
A study of the influence during trituration of air‐borne impurities on the strength of amalgam
Authors: Hansen David A. , Holland John W. , Lewis Stephen A. , Moore David L. 
Published: December 2004

AbstractThe 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.
A preliminary report on thirty‐five geometric total knee arthroplasties
Authors: Fortune William P. , Adams John P. 
Published: December 2004

AbstractThis 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.
Porous titanium dental implants
Authors: Young F. A. 
Published: December 2004

AbstractTitanium 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.
Hemiarthroplasty: A histological and scanning electron microscope study
Authors: Cameron Hugh U. , Macnab Ian , Anderson William 
Published: December 2004

AbstractThe 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.
Determination of mercury vapor pressure over amalgams from weight loss data
Authors: Reynolds C. L. 
Published: December 2004

AbstractMercury 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.
Tracer diffusion of silver and tin in a dental alloy (Ag3Sn)
Authors: Okabe Toru , Hochman R. F. , McLain M. E. 
Published: December 2004

AbstractThe 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 D \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop = \limits_ \cdot $\end{document} 1.03 × 10−3 exp (−22,400/RT) and D = 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.
Reduction of maximum temperature in the polymerization of cold‐ and heat‐curing acrylic resins
Authors: de Wijn J. R. 
Published: December 2004

AbstractKinetic 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.
Thermal properties of cancellous bone
Authors: Calttenburg Richard , Cohen Jonathan , Conner Scott , Cook Nathan 
Published: December 2004

AbstractSpecimens of beef bone were analyzed for thermal conductivity and thermal capacity. The thermal conductivity was about 7 × 10−4 cal/cm/sec/°C, that is about the same as for other tissues. As regards thermal capacity, the determination of 0.73 cal/cm2/°C also was similar to that in other tissues Both thermal conductivity and capacity were isotropic with respect to the layer of epiphyseal cartilage, and the orientation of bony trabeculae.Thermal probes were devised heated either by water or by electric current to destroy localized volumes of bone, as in surgery. To achieve necrotizing temperatures, the sizes of such probes and the times of application of heat were determined.
Auger analysis of surface films on Ag3Sn
Authors: Grenga Helen E. , Carden John L. , Okabe Toru , Hochman Robert F. 
Published: December 2004

AbstractThe surface properties of Ag3Sn are important in the amalgamation process so that mechanical abrasion is generally necessary to get a satisfactory amalgam. Therefore, the present study was undertaken to characterize the surface of Ag3Sn after several types of surfaces treatments.Homogeneous polycrystalline rods of Ag3Sn were prepared in vacuo from high purity (99.99%) Ag and Sn. Specimens were sliced from these rods and prepared as follows: (1) mechanically polished, (2) polished as in (1) and allowed to sit in air for three days and (3) polished as in (1) and electrolytically etched. Each of these specimens was examined by Auger electron spectroscopy.The results showed that after mechanical abrasion the surface film was primarily oxide and the Ag to Sn ratio was lower than the bulk composition, indicating preferential oxidation of Sn. After sitting in air sulfur was also present on the surface and the Ag to Sn ratio was greater than that immediately after polishing, indicating the formation of Ag2S. After electrolytic etching some oxide was still present, but only a trace of sulfide was found. However, the Ag to Sn ratio was greater than that for mechanically polished specimens, indicating preferential dissolution of Sn. Therefore, it is seen that the surface preparation of Ag3Sn has a marked effect on Ag and Sn concentrations and the nature of films at the surface.
Modified collagen membrane as a skin substitute: Preliminary studies
Authors: Tavis Michael J. , Harney John H. , Thornton James W. , Bartlett Robert H. , Woodroof E. Aubrey 
Published: December 2004

AbstractModified collagen membrane when compared to autograft, homograft, heterograft and silicone polymer memberane, demonstrated a superior adherence on split and full‐thickness surfaces, but proved to be an inferior covering for granulating surfaces. Water vapor transport was found to be adequate and adaptable to modification. It was found to be permeable to most commonly used topical antibiotics, and no significant antigenicity could be demonstrated. In a controlled animal burn study, modified collagen membrane proved superior to homograft and heterograft in regard to mortality, time to grafting, bacteriology and autograft take. These studies provide a background for further laboratory and clinical studies now in progress.
MP35N: A corrosion resistant, high strength alloy for orthopedic surgical impants: Bio‐assay results
Authors: Escalas Felix , Galante Jorge , Rostoker William , Coogan Philip S. 
Published: December 2004

AbstractA cobalt based alloy, MP35N, with excellent mechanical properties has been recently introduced as a material for surgical orthopedic implants.A study was made of local and systemic host response to this material in two different mammal species. The implantation time ranged from one to 12 months.The result of this study indicated: MP35N produces a degree of local tissue response comparable to that of 316L stainless steel. No sytemic side effects were observed during the implantation times included in this study.
Experiences with Al2O3 implantations in humans to bridge resection defects
Authors: Engelhardt A. , Salzer M. , Zeibig A. , Locke H. 
Published: December 2004

AbstractVarious implants have been developed for the upper and lower extremities and the spine. In order to establish whether endoprostheses made of Al2O3 will show the same good biocompatibility in humans as it has in experiments with animals, endoprostheses implantations were performed in 4 patients: 2 upper arms, 1 radius, 1 vertebra body. The implants were exposed to various loads. The biomechanical conditions were considered in the construction. The results reveal that the knowledge of material properties and prior calculations make possible the development of satisfactory endoprostheses. X‐ray examinations confirm these deductions. Good functionality was achieved in vivo with all implants. They were all mechanically anchored, no bone cement was used. Thus the biocompatibility of the material was not limited. A histological examination is made of one implant. The macroscopic examination showed a stable fit and no pathological reactions. X‐rays revealed that the bone remained in good contact with the implant. The longest observation period was over 1 1/4 years. Present observations show that the use of Al2O3 implants, without the use of additional materials (bone cement), results in a tight fit of the implants.
Thromboresistance of glass after glow discharge treatment in argon
Authors: Baier R. E. , Depalma V. A. , Furuse A. , Gott V. L. , Kammlott G. W. , Lucas T. , Sawyer P. N. , Srinivasan S. , Stanczewski B. 
Published: December 2004

AbstractGlow discharge treated (GDT) inorganic materials are sterile and free of all organic contaminants. Such materials implanted in the canine inferior vena cava often demonstrate significant thromboresistance. Standard Pyrex glass tubing was GDT in argon to provide a surface free energy above 70 dynes/cm, slight surface negativity, and other surface‐physical modifications of its interface. Chromic acid cleaned lengths of the same tubing, and short segments whose edges were not fire‐polished were used as controls. Upon canine implantation, the in vivo results were similar in independent surgical laboratories. The glass was implanted as 1.4 cm long rings or as 5 cm long tubes in separate medical centers according to different protocols. GDT specimens remained patent; all controls accumulated thrombi. A remarkably pure, low critical surface tension, labile protein coating covered all cylindrical lumens after 2 hr in vivo. This coating diminished within 2 weeks and was essentially absent after 480 days, even though scanning EM showed evidence of a micron thick luminal film, probably eroding glass. No emboli were found in the implant animal's kidney or lungs at any stage.
Relative thrombogenicity of polydimethylsiloxane and silicone rubber constituents
Authors: Weathersby Paul K. , Kolobow Theodor , Stool Edward W. 
Published: December 2004

AbstractMedical grade silicone rubber (MGSR) is composed of polydimethylsiloxane (PDMS) as well as silica filler, oxidation products from the curing process, and other components. In a test that excludes air‐blood interfaces, PDMS radiation cured under nitrogen has a whole blood clotting time 22% longer than MGSR. Curing the PDMS under oxidizing conditions maintains a 10% prolongation, but addition of silica filler to the PDMS returns the clotting time to that of MGSR. Extracting MGSR with solvents other than water appreciably lowers the clotting time. These results indicate that “pure” PDMS has an intrinsically high thromboresistance. Thrombogenicity is increased by the use of silica filler and oxidizing cure, as in MGSR.
Biological evaluation of polymers I. Poly(methyl methacylate)
Authors: Dillingham E. O. , Webb N. , Lawrence W. H. , Autian J. 
Published: December 2004

AbstractA series of poly(methyl methacrylate) formulations differing widely in chemical and physical properties was employed for the evaluation of primary screening methods for the assessment of acute toxicity. Materials and USP extracts of materials were tested in parallel. Tissue culture, hemolysis, intradermal irritation, systemic toxicity, muscle implant and histopathologic responses were determined for each of 27 formulations. A determination of the nonvolatile methanol extractable components was carried out on each formulation. The formulations varied with respect to percent, w/w, methyl methacrylate, N,N‐dimethyl‐p‐toluidine, stannous octoate, 3,4‐diamino‐toluene and, also, with respect to curing conditions. Volatile components, primarily methyl methacrylate, of three selected formulations were determined quantitatively by vacuum distillation and mass spectrographic analysis.Statistical analysis of the primary data indicated a significant correlation of residue weight (methanol extractable) with hemolytic activity (r = 0.93) and with the cumulative biological response (r = 0.9). Multiple linear regression analysis of residue weights with hemolysis and intradermal irriation responses gave the highest overall correlation (r = 0.96). Hemolytic activity and tissue culture responses were significantly correlated (r = 0.87). It was concluded that the observed variation of biological test results reflected significant differences in the toxicity of the test materials. The poly(methyl methacrylate) series examined was relatively low in toxicity and the biological tests examined, particularly the in vitro tests, were found to be responsive to formulation and curing conditions which indicated their suitability for primary toxicity screening.
The influences of electrical potential and surface finish on the fatigue life of surgical implant materials
Authors: Bapna M. S. , Lautenschlager E. P. , Moser J. B. , Meyer P. R. 
Published: December 2004

AbstractThe influence of both imposed anodic potential in Ringer's solution and surface finish on the fatigue lives of annealed 316 type stainless steel and annealed pure titanium were measured and statistically compared to fatigue data run in air. The applied potentials in simulated extracellular fluid approximated conditions existing within the body while also producing the types of surface defects actually found on removed long time implants within the time interval of the accelerated R. R. Moore fatigue tests. Differentiating tests were run at single levels of applied cyclic stress well above the endurance limits.In Ringer's solution, the fatigue life of the 316 stainless steel decreased with increasing applied potential, and at +500 mV was significantly shorter than when run in air. At each condition, the 316 stainless steel was independent of initial surface finish. In contrast, the fatigue life of titanium improved rapidly with increasingly fine surface finishes. Furthermore, compared to air, the application of +500 mV in Ringer's solution improved the life of the rough surface finished material and markedly increased the number of cycles to failure for the electropolished specimens.
Ultrathin coating by plasma polymerization applied to corneal contact lens
Authors: Yasuda H. , Bumgarner M. O. , Marsh H. C. , Yamanashi B. S. , Devito D. P. , Wolbarsht M. L. , Reed J. W. , Bessler M. , Landers M. B. , Hercules D. M. , Carver J. 
Published: December 2004

AbstractPlasma coating (deposition of polymer under the influence of plasma) is utilized to modify the surface properties of corneal contact lens. An ultrathin layer (thickness of roughly 200 Å) of plasma polymer of acetylene/H2O/N2 is applied to poly(methyl methacrylate) (PMMA) corneal contact lenses. The surface becomes highly wettable with water compared to uncoated lens. When coated and uncoated contact lenses are placed on rabbit eyes, a remarkable difference in accumulation of mucous matter is observed. With the control lenses, the accumulation of mucous matter in a week is sufficient to affect the optical clarity of the lenses, whereas the coated lenses show no change after three months continuous wearing. The comparative degree of adhesion of the corneal epithelium cells onto glass, modified glass, PMMA, and coated PMMA surfaces is studied using tissue cultures and phase contrast microscopy. The coated PMMA surface exhibits a degree of tissue adhesion lower than that of control PMMA and higher than that of glass surface, and no sign of toxicity of the coated surface is observed by the tissue cultures.
Pharmacological properties of the plasticizer, acetyl N‐tributyl citrate, and its extraction from poly(vinyl chloride) tubing
Authors: Hollingsworth M. 
Published: December 2004

AbstractAqueous extracts of a PVC transfusion tubing contracted isolated guiea‐pig ilea. A pharmacological and chemical study (infrared spectroscopy, gas–liquid chromatography) showed that this was due to extration of the plasticizer, acetyl N‐tributyl citrate (ATBC). The concentrations of ATBC to produce contractions of the isolated guinea‐pig ileum (from 1 μg/ml) can be compared with those achieved after recirculating tubing under conditions simuflating use (up to 6 μg/ml).In assenssing the toxicity of plastic tubing, there is a need to determine extraction of constituents under conditions simulating use and the effects of such extracts on a cariety of tissues.
Microstructure in gold‐containing Ag3Sn‐amalgam
Authors: Malhotra Manohar L. 
Published: December 2004

AbstractThe present study was conducted in order to understand the microstructural characteristics in dental amalgam which consists of both spherical and irregular Ag3Sn alloy particles with gold substituted in varying amounts for silver (0, 9, and 15%). Spherical alloy particles were used as obtained from Western Gold and Platinum and irregular alloy particles were prepared in the laboratory and then employed in the present study. The amalgam was prepared from the alloy particles by the trituration and condensation method. The polished and etched samples were studied using the techniques of X‐ray diffraction, optical metallography, scanning electron microscopy, and X‐ray energy dispersive spectroscopy. The microstructure in both types amalgam studied after two weeks of preparation contains γ (unreacted Ag3Sn particles), γ1 (Ag2Hg3), and γ2 (Sn7–8Hg) phases in pure Ag3Sn‐amalgam and γ, γ1, and (Au–Sn) phases in gold‐containing amalgam. The (Au–Sn) phase existed in the form of rings surrounding the γ grains and acted as a barrier for mercury diffusion in Ag3Sn particles.
The rate of bone ingrowth into porous metal
Authors: Camron H. U. , Pilliar R. M. , Macnab I. 
Published: December 2004

AbstractExperiments have been devised to study the rate of ingrowth of bone into porous metal with pore sizes up to 100 μ and to study the significance of a gap between the porous metal surface and bone.When the porous coat was in direct apposition with bone, the implant was firmly locked in place after a three week period and the plateau value of implanttissue shear strength was reached at four weeks. A gap of 1.5 mm between the bone and the implant was bridged by new bone wihtin four weeks.
Diffusion of mercury in Ag2Hg3 from weight‐loss data
Authors: Timmons C. F. , Hines A. L. , Lightsey G. R. , Okabe T. 
Published: December 2004

AbstractThe weight‐loss method was employed to determine the diffusion coeffcients of mercury in Ag2Hg3 alloy at temperatures in the range of 64–120°C. Diffusion coeffcients for nonhomogeneous specimens obey the relationship:

Diffusion coeffcients for nonhomogeneous samples were found to be an order of magnitude greater than values found for homogeneous samples.