bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of the general features of the soft tissue response to some metals and ceramics using quantitative histomorphometry
Authors: Therin M. , Christel P. , Meunier A. 
Published: May 2005

AbstractThis article analyzes the general features of the tissue response to orthopedic biomaterials when implanted in the paraspinal muscles in rats for periods between 1 week and 1 year. Using a computer‐assisted cell counting method, it was shown that the membrane thickness was a stable parameter that poorly correlated with the other histomorphometric parameters except fibrocyte distance parameters. Macrophages were significant in number only in the short term and were always located at the implant‐tissue interface. At 4 weeks, the period corresponding to which macrophages disappeared, fibrocytes were found nearer the interface than at earlier periods and did not migrate for up to 52 weeks, although their densities decreased to 50% of their initial values. Therefore, it can be histomorphometrically confirmed that (1) the presence of an implant induced a delay in the healing process; (2) the immune system was not usually involved in the response to bulk metals; and (3) at early time periods, the presence of PMN cells was correlated to the long‐term number of macrophages. On the contrary, the histomorphometric findings suggested that around the tested materials, a large number of macrophages did not induce an immediate or a delayed fibrocyte proliferation. If one considers that a low fibrocyte surface density is related to activated cells surrounded by a matrix high in collagen content, then the large number of macrophages induced the stimulation of collagen synthesis by the fibrocytes already included in the membrane. Accordingly, in the short‐term, a high fibrocyte density and few macrophages may be a criterion for testing biocompatibility. © 1994 John Wiley & Sons, Inc.
Isolation and characterization of metallic wear debris from a dynamic intervertebral disc prosthesis
Authors: Schmiedberg Stefan K. , Chang Dennis H. , Frondoza Carmelita G. , Valdevit Antonio D. C. , Kostuik John P. 
Published: May 2005

AbstractA dynamic intervertebral disc prosthesis (DIDP) has been developed. It consists of a CoCrMo body and uses Ti6A14V springs to replicate the mechanical function of the lumbar joint. Wear studies have been performed previously on the DIDP using two specialized simulators to test the wear properties of the moving parts of the disc prosthesis. A pin‐in‐slot simulator generates wear that would occur in the hinge‐pin assembly of the prosthesis. A spring‐in‐pocket simulator approximates the conditions under which the springs would wear against the body of the prosthesis. The spring‐pocket interface is responsible for the production of approximately 90% of the total wear occurring in the prosthesis, and is therefore the main focus of this study. Bovine serum with a preservative has been used as a lubricant in both simulators. The spring‐in‐pocket simulator compares the effects of two different manufacturing techniques of CoCrMo (HIPing and forging) on their wear characteristics against Ti6A14V springs. Debris from the spring‐in‐pocket simulator has been isolated from the serum lubricant and characterized using scanning electron microscopy techniques. The morphology of the Ti6Al4V fragments is rough and irregularly shaped. The size of these fragments ranges from <1 μm. to > 30 μm. The forged CoCrMo alloy debris has an irregular polyhedral shape, with sizes in the same range as the spring fragments. The morphology of the HIPed CoCrMo debris is spherical with a size range <5 m̈m to >30 μm. Length and width measurements of micron‐size particles were made with the particle measurement feature of the scanning electron microscope. Micron‐size particles were found in all stations. This article provides a unique way to isolate and analyze debris from serum lubricants used in simulators. © 1994 John Wiley & Sons, Inc.
Titanium fiber mesh anchorage for percutaneous devices applicable for peritoneal dialysis
Authors: Paquay Y. C. G. J. , De Ruijter J. E. , van Der Waerden J. P. C. M. , Jansen J. A. 
Published: May 2005

AbstractIn previous experiments a new type of percutaneous device for implantation in soft tissue was designed. The subcutaneous component of the new device consists of a sintered titanium fiber web. The percutaneous devices are inserted by a so‐called „two‐phase”︁ surgical technique with an intervening healing period of 3 months between the insertion of the subcutaneous flange and the placement of the percutaneous part. From a clinical point of view, this time interval is too long. Therefore, the aim of this study was to investigate a possible reduction of the intervening healing period. The implants were inserted in the backs of 18 rebbits. In each rabbit, six implants were placed with intervals of 1 week. Consequently, at the end of the experiment, in each rabbit six implants were present with implantation periods ranging from 5–10 weeks. After 10 weeks, the animals were sacrificed and the implants with their surrounding tissues were processed histologically. Light microscopic and histomorphometric analysis demonstrated that there was no difference in tissue response between the various implantation periods. Furthermore, it was found that the fiber mesh material showed good biocompatible behavior. In conclusion, the experiment has demonstrated that for titanium mesh percutaneous devices a 5‐week healing period is sufficient between the installation of the subcutaneous and percutaneous parts. © 1994 John Wiley & Sons, Inc.
Studies on calcium phosphate precipitation: Effects of metal ions used in dental materials
Authors: Okamoto Y. , Hidaka S. 
Published: May 2005

AbstractThe effects of 26 metal ions, of which 23 are used in dental materials, on the conversion of amorphous calcium phosphate (ACP) to hydroxyapatite (HAP) in vitro were studied. From the effects on both the rate of HAP transformation and induction time, effects of metal ions were classified into three types; inhibitory (in the order: nickel, tin, cobalt, manganese, copper, zinc, gallium, thallium, molybdenum, cadmium, antimony, magnesium, and mercury); ineffective (cesium, titanium, chromium, iron [ferrous], iridium, palladium, platinum, silver, gold, aluminum, and lead); and stimulatory (iron [ferric] and indium). These results suggest that metal ions used in dental materials may modify the precipitation of oral calcium phosphate. © 1994 John Wiley & Sons, Inc.
Dual constant composition kinetics characterization of apatitic surfaces
Authors: Paschalis E. P. , Wikiel K. , Nancollas G. H. 
Published: May 2005

AbstractThe use of calcium phosphate phases as implant materials in forms such as ceramic hydroxyapatite (CHAP) and hydroxyapatite plasma‐coated implants (HPCTI) as well as the synthetic phases is now quite well established. Although conventional physical chemical charaterization methods such as X‐ray diffraction may indicate the exclusive presence of hydroxyapatite (HAP), there is little doubt that other calcium‐containing surface impurities play important roles in the initial reactions that take place when such materials are brought into contact with aqueous phases. These surface impurities usually dissolve rapidly with the release of excess calcium and hydroxide ions. Based on the constant composition (CC) method, the dual constant composition (DCC) approach has been developed for investigating the dissolution kinetics behavior of these apatitic materials in an attempt to characterize and modify the surfaces, and possibly to predict their behavior when placed in vivo. The results of this study confirm the presence of highly reactive heterogeneous calcium‐containing phases on the surface of materials such as CHAP and HPCTI, as evidenced by the release of appreciable amounts of calcium and hydroxyl ions upon introduction of these surfaces in saline solutions. Furthermore, these calcium phosphate phases exhibited a unique dissolution behavior when compared with synthetically prepared phases such as HAP and β‐tricalcium phosphate (β‐TCP), as suggested by the observation that they dissolve in solutions supersaturated with respect to HAP. © 1994 John Wiley & Sons, Inc.
Surface energy characterization of unalloyed titanium implants
Authors: Kilpadi Deepak V. , Lemons Jack E. 
Published: May 2005

AbstractOsteointegration is dependent on a variety of biomechanical and biochemical factors. One factor is the wettability of an implant surface that is directly influenced by its surface energy. This investigation used the Zisman plot to determine critical surface energy. The effects of surface treatment, bulk grain size, and surface roughness on the critical surface tension of unalloyed titanium (Ti) were examined. Radio frequency glow discharge‐treated Ti had the highest critical surface tension, followed by the passivated and heat‐sterlized conditions. Titanium with no surface treatment had the lowest critical surface tension. The surface energy of Ti with an average grain size of 23 μm was not significantly different from that with a grain size of 70 μm. Surface roughness was shown to cause significant difference in measurements and definitely should be considered in studies of this kind. © 1994 John Wiley & Sons, Inc.
Atomic force microscopy studies of the interaction of a dentin adhesive with tooth hard tissue
Authors: Cassinelli C. , Morra M. 
Published: May 2005

AbstractThe usefulness of atomic force microscopy (AFM) in the study of dental biomaterials was investigated. Two basic points were addressd: the first is the use of an atomic force microscope for the imaging of tooth hard tissue; the second is a study by AFM of the interaction of a liquid adhesive (Gluma) with dentin. Results show that dental tissues are readily imaged by AFM and that high‐resolution images of the dentin ultrastructure can be obtained. As to the dentin adhesive, it was possible to elucidate the mechanism of action of Gluma. In particular, polymerization of the hydroxyethylmethacrylate present in the Gluma mixture was observed to occur in <30 seconds. © 1994 John Wiley & Sons, Inc.
Inflammatory response and degradation of three types of calcium phosphate ceramic in a non‐osseous environment
Authors: van der Meulen J. , Koerten H. K. 
Published: May 2005

AbstractThe cellular response and inflammatory reaction to three types of calcium phosphate ceramic spheres, namely fluorapatite (FA), hydroxyapatite (HA), and β‐tricalcium phosphate (TCP), were investigated. The degradation at ultrastructural level of these ceramics was also studied. The mouse peritoneal cavity was used as a model compartment for this study. To minimize the influence of a wound reaction, the spheres were implanted by injection. Intraperitoneal injection of lates beads of 6.4 and 25.7 μm showed that an inflammatory reaction is influenced by the size of injected particles; therefore, ceramic spheres with the same average diameter (11.3 μm) were used. After 2 and 4 days and 1, 2, 4, 8, 12, and 24 weeks, the spheres were harvested. All materials gave rise to a short, mild inflammatory reaction. The ceramic spheres aggregated rapidly, and foreign body granulomas were formed within 2 weeks. Degradation of all materials was observed in this study, and degradation products were frequently seen both intracellularly and extracellularly. After 2 weeks TCP and HA showed the formation of crystals at their surface and between individual grains of the spheres. This was most prominently seen with TCP. At 4 weeks, HA and TCP granulomas showed the formation of extracellular, globular deposits between macrophages or multinucleated giant cells and fragments of the ceramic. They consisted of an organic matrix containing apatite‐like crystals and iron, and had an average diameter of 10 μm. The number of deposits was the highest for TCP. For FA, calcium phosphate precipitation and the formation of deposits was not observed before the 8‐week interval and remained at a low level. © 1994 John Wiley & Sons, Inc.
Effect of 2‐amino oleic acid exposure conditions on the inhibition of calcification of glutaraldehyde cross‐linked porcine aortic valves
Authors: Chen Weiliam , Kim John D. , Schoen Frederick J. , Levy Robert J. 
Published: May 2005

AbstractPostimplant calcific degeneration is a frequent cause of clinical failures of glutaraldehyde cross‐linked porcine bioprosthetic heart valves (BPHV). It was demonstrated previously that 2‐amino oleic acid (AOA) used as a bioprosthesis treatment was highly effective in mitigating aortic valve cusp but not aortic wall calcification. Our main objective was to study the efficacy of various AOA exposure conditions for inhibiting calcification of both cusps and aortic wall tissues using rat subdermal implants. BPHV tissues were treated with a saturated AOA solution for different time intervals before experimentation. Aortic wall AOA levels were consistently lower than that of the cusps after the same exposure times. The diffusion of calcium ion across both cusp and aortic wall tissues was evaluated, and the results demonstrated that there was an AOA exposure time‐dependent retardation of calcium ion penetration for cusp but not aortic wall. An 8‐month extraction study was performed to determine the stability of AOA binding. When Tween 80 was used as an extraction medium, cusp and aortic wall retained 12.9 and 48.7%, respectively, of their initial AOA levels. AOA inhibition of calcification in rat subdermal implants (60 days) was found to be exposure time‐dependent with maximum treatment time (120 h), resulting in the lowest calcium levels (20.1 ± 10.3 and 71.4 ± 5.4 μg/mg of cusp and aortic wall, respectively) as compared with control (219.1 ± 6.8 and 104.9 ± 8.5 μg/mg of cusp and aortic wall respectively). The significance of AOA binding on BPHV tissue was determined by either blocking or reducing BPHV's (cusp and aortic wall) free aldehyde residues with lysine or NaBH4, respectively, before AOA treatment. For aortic cusps, the AOA contents after 72 h were 98.3 ± 2.7, 34.2 ± 3.6, and 54.1 ± 3.0 nM/mg of tissue for AOA (control), lysine‐pretreated (plus AOA) and NaBH4‐pretreated (plus AOA) tissues, respectively. However, their calcium levels after 60 days of rat subdermal implant were all comparable (i. e., 48.1 ± 6.2, 38.2 ± 9.1, and 47.0 ± 15.0 μg calcium per mg of tissue). Similar results were observed on BPHV aortic wall. It can thus be concluded that AOA inhibition of BPHV calcification is exposure time‐dependent, but the efficacy of AOA for aortic wall is less than that noted for aortic cusps, perhaps because of lower AOA bindings and differences in calcium diffusion kinetics. © 1994 John Wiley & Sons, Inc.
Formation and characterization of anodic titanium oxide films containing Ca and P
Authors: Ishizawa Hitoshi , Ogino Makoto 
Published: May 2005

AbstractCommercially pure titanium was anodized in an electrolytic solution that was dissolved calcium and phosphorus compounds in water, and an AOFCP (anodic titanium oxide film containing Ca and P) was formed. It was found that sodium β‐glycerophosphate (β‐GP) and calcium acetate (CA) were suitable for the electrolytes to form the AOFCP having an equivalent Ca/P ratio to hydroxyapatite (HA). The AOFCP was characterized by scanning electron microscopy (SEM), an energy‐dispersive X‐ray microanalysis (EDX), and X‐ray diffraction (XRD). Numerous micropores and microprojections were observed on the AOFCP by SEM. The composition of the AOFCP, which was measured by EDX, changed according to β‐GP and CA concentration, and the electrolytic voltage. Ca and P in the AOFCP seem to be incorporated into the TiO2 matrix from CA and β‐GP in the electrolyte during the anodic oxidation. Despite the existence of Ca and P in the AOFCP, no calcium phosphate peak was detected by XRD, and the AOFCP consisted of anatase and only a little rutile. The AOFCP, whose contents of Ca and P were low, had a high adhesive strength after soaking in a simulated body fluid for 300 days. When the AOFCP having an equivalent Ca/P ratio to HA was hydrothermally heated at 300°C, HA crystals were precipitated on the AOFCP and completely covered the surface. © 1995 John Wiley & Sons, Inc.
Initial bone matrix formation at the hydroxyapatite interface in vivo
Authors: de Bruijn J. D. , van Blitterswijk C. A. , Davies J. E. 
Published: May 2005

AbstractDense, sintered, slip‐cast hydroxyapatite rods were implanted transfemorally in young adult rats. The femora were excised after 2 and 4 weeks and, following fixation, either embedded in methyl methacrylate for light microscopy, decalcified and prepared for transmission electron microscopy, or freeze fractured in liquid nitrogen for scanning electron microscopic analysis. The latter was performed on the two tissue fragments that remained after freeze fracturing, from which the first contained the implants and the second comprised tissue that had been immediately adjacent to the hydroxyapatite rods. Undecalcified light microscopic sections revealed extensive bone tissue formation around and in contact with the hydroxyapatite rods. The initial bone matrix apposed to the implant surface, as demonstrated with scanning electron microscopy, was either composed of globular deposits or an organized network of collagen fibers. The deposits, which ranged in size from 0.1–1.1 μm, fused to form a cement‐like matrix to which collagen fibers were attached. Degradation of the hydroxyapatite surface resulted in the presence of unidirectionally aligned crystallites, with which the newly formed bone matrix was closely associated. Ultrastructural analysis of the bone‐hydroxyapatite interface with transmission electron microscopy revealed a 50–600‐nm‐wide collagen‐free granular zone, comprising one or more 40–100‐nm‐thick electron‐dense layer(s). These structural arrangements most probably partially represent the globular deposits and proteinaceous material adsorbed onto and partially in the degrading hydroxyapatite surface. Although the latter change in surface topography may have enhanced bonding of the cement‐like matrix to the hydroxyapatite, the cause for this change in topography and the type of bond formed are, at present, unknown. © 1995 John Wiley & Sons, Inc.
Immunofluorescence and confocal laser scanning microscopy studies of osteoblast growth and phenotypic expression in three‐dimensional degradable synthetic matrices
Authors: Attawia Mohamed A. , Devin Jessica E. , Laurencin Cato T. 
Published: May 2005

AbstractIn the development of three‐dimensional cell‐polymer synthetic matrices for tissue regeneration, visualization of cells growing in these porous structures can be difficult. The focus of this study was the development and use of a novel method that would allow for visualization of osteoblasts inside opaque matrices. The morphologic responses and phenotypic characterization of osteoblasts as they attach, spread, and migrate through a porous three‐dimensional biodegradable polymer‐ceramic matrix in vitro were studied using immunofluorescence and confocal laser scanning microscopy (CLSM). CLSM offers several advantages over the most commonly used imaging methods [traditional light microscopy and scanning electron microscopy (SEM)]. CLSM filters out‐of‐focus background and provides more structural details of cells. In addition, CLSM does not require extensive sample preparation as does SEM. When used in conjunction with fluorescence‐labeled antibodies to identify cells and their products, it can characterize morphology of growing cells and successfully determine phenotypic function. Using monoclonal antibody to osteocalcin, a bone cell‐specific protein, cells throughout the matrix were found to have preserved osteoblast‐like phenotype with growth. The morphology of cells throughout the matrix was found to be similar to osteoblast cells grown on tissue culture polystyrene and consisted of spread polygonal forms. Using the technique of CLSM with immunofluorescent antibodies, we have demonstrated for the first time that these three‐dimensional degradable polymer matrices can support osteoblast growth and phenotypic expression throughout its structure. © 1995 John Wiley & Sons, Inc.
Low‐voltage scanning electron microscopic imaging of ultrahigh‐molecular‐weight polyethylene
Authors: Pienkowski David , Jacob Robert , Hoglin Dennis , Saum Kenneth , Kaufer Herbert , Nicholls Paul J. 
Published: May 2005

AbstractSubmicron ultrahigh‐molecular‐weight polyethylene (UHMWPE) wear particles from total joint prostheses may contribute to implant failure through particle‐mediated aseptic loosening. The purpose of this study was to examine the microstructure of virgin UHMWPE powder to determine its morphology for future comparison with wear debris. A new method of low‐voltage scanning electron microscopy (LVSEM) in an oil‐free vacuum was applied, which produced high‐resolution images of UHMWPE micromorphology, while minimizing specimen damage and obviating the need for image processing. GUR 415 UHMWPE virgin powder particles were examined by using routine high‐voltage SEM, LVSEM, and image analyses. LVSEM showed that UHMWPE particles were composed of submicron‐size spherical subparticles connected by numerous nanometer‐size fibrils. These spherical subparticles had a highly textured surface morphology seen only by LVSEM. Fracture of the nanometer‐size fibrils was observed. Routine high‐voltage SEM obfuscates the intricate and delicate UHMWPE micromorphology as well as the damage done by the accompanying high‐voltage electron. This study suggests that the micromorphology of wear particles previously studied with routine high‐voltage SEM was overlooked or damaged, justifies the need for LVSEM in future studies, and raises the question of what is the true morphology of polyethylene wear debris retrieved from human tissues. © 1995 John Wiley & Sons, Inc.
Distribution of titanium and vanadium following repeated injection of high‐dose salts
Authors: Merritt Katharine , Brown Stanley A. 
Published: May 2005

AbstractTitanium and its alloy of 6% aluminum and 4% vanadium are used extensively in orthopedic and dental surgery. However, in conditions of motion leading to wear, there is significant generation of wear products with deposition of black debris in the tissue. The questions remain as to how much of this debris is generated and to where it is transported. Previous studies have been hampered by low levels of detected elements giving values just above the background levels found in normal tissue and body fluids. The purpose of these experiments was to increase the body burden of titanium and vanadium by injecting larger doses of titanium and vanadium salts over an extended period of time. Each animal (Syrian hamster) received 100 μg of each element once a week for six weeks. The hamster was sacrificed on the seventh week and body fluids and tissue harvested. The results indicate that in the experimental animals there was transport of vanadium with levels above control in urine, plasma, liver, spleen, and the mineralized portion and organic portion of bone. Titanium had less transport but still showed levels in the experimental animals in plasma, kidney, liver, spleen, and both phases of bone above those in the control animals. Neither element was found above control levels in lung or red blood cells. The levels of titanium and vanadium in control bone were high, possibly indicating bone as a site for storage and accumulation of these elements when encountered in the activities of daily living. © 1995 John Wiley & Sons, Inc.