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PubMed1990

The in vivo auto-oxidation of polyether polyurethane by metal ions.

The first large scale use of polyether polyurethane elastomers in long term human implants was as insulation for cardiac and neurologic pacing leads. While the performance of these polymers has generally been very good over a 14-year period, several failure mechanisms have been discovered that involve interactions between the devices, materials and the body. One of these is auto-oxidation of soft segment ether through the intermediate action of certain transition metal ions, derived from conductor wires by corrosion processes. Biologically produced oxidants appear to be an accelerating factor. In this study, Pellethane 2363-80A tubing containing conductor coils or mandrels of various metals or controls were implanted in rabbits. Explants were analyzed as a function of implant time by optical and scanning electron microscopy, electron dispersive analysis by X-ray, stress-strain, FTIR, GPC and AA spectrophotometry. Only cobalt produced bulk oxidative degradation while surface damage was found in the presence of cobalt bearing alloys. No evidence of significant auto-oxidation was found in the presence of silver, nickel, chromium, molybdenum, iron, titanium, platinum, 304 stainless steel, glass or empty tubing. The combination of polyether polyurethane and metals (especially those containing cobalt) in an implantable device must be carefully evaluated for biostability prior to human use.

Biocompatible Materials↗
PubMed1990

Clinical and histological findings in ligature-induced experimental periodontitis in dogs. A pilot study.

Prior to experimental periodontal regenerative procedures in animals, the process of destruction due to periodontitis is often simulated by placing ligatures around the necks of teeth. 2 models, one using cotton floss ligatures and the other elastic rubber ligatures, have been widely used. The aim of this study was to compare these 2 methods using clinical and histometric criteria. Premolars on both sides of the mandibular jaw were used in 2 beagle dogs. Periodontal tissue breakdown was induced during a 48-day period using cotton floss ligatures on one side of the mandible and contra-laterally by elastic rubber ligatures. At weekly intervals, the ligatures were changed and pocket depth and loss of probing attachment were recorded. All the ligatures were removed after 7 weeks. The animals were fed a soft, plaque-promoting diet during the experimental period. 20 days after ligature removal, the teeth were hemisected and the 2 roots extracted. From each tooth, 1 root was prepared for scanning electron microscopy and one for light microscopy. At the time of extraction, no differences regarding pocket depth or probing attachment level were found between the 2 groups. Root resorption was observed in all elastic ligature teeth, whereas only minor alterations at the root surface were observed on cotton ligature teeth. This finding may be of particular interest to investigators designing studies evaluating the healing sequalae of regenerative surgery in animals. As was observed in this study, root resorption can already be present in the pre-experimental phase of periodontal tissue breakdown, particularly if elastic ligatures are used.

Animals↗
PubMed1996

Effect of a specially formulated remineralizing solution on the remineralizing capacity of saliva.

The present study was carried out to assess whether the remineralization of artificial caries like lesion by artificial saliva can be improved by daily 5 minute treatment in a specially formulated remineralizing solution containing Ca, P, Zn, Sr, F. Extracted human premolars were dipped for 24 hours in artificial saliva and subsequently daily for 5 minutes in the remineralizing solution for 3 weeks. Lesions were assessed using transverse microradiography, electron probe microanalysis (EPMA) and scanning electron microscope (SEM). The results showed that remineralization by specially formulated solutions repair the enamel lesion and enhances the salivary remineralizing potential.

Bicuspid↗
PubMed1994

Shear strength of ceramic brackets bonded to porcelain.

The purpose of this study was to compare the bond strengths of three different adhesive systems when used alone and combined with a porcelain priming agent to bond ceramic brackets to porcelain surfaces. Sixty porcelain specimens were randomly assigned to the six different treatment groups. Half were bonded with the porcelain priming agent and one of the adhesive systems and the other half with one of the adhesive systems alone. The shear bond strengths of all specimens were tested, with an Instron testing machine, 10 minutes after being bonded. The surface of the porcelain and the bracket base were examined, with scanning electron microscopy (SEM) and qualitative energy dispersive x-ray analysis (EDS), to determine the bond failure patterns and to check the porcelain surface for the presence of cracks and fractures. There was a statistically significant difference within each adhesive between those samples with the priming agent and those without the priming agent. Differences between the three adhesives were not statistically significant (p < or = 0.05).

Acid Etching, Dental↗
PubMed1993

Chemical analysis of a dens invaginatus by SEM microanalyses.

A patient with a supernumerary right maxillary lateral incisor with dens invaginatus presented. After extraction, the invaginated area of the tooth as well as another of similar ages but with normal hard tissues, were prepared for scanning electron microscopic observation. Outer and invaginated enamels were identified the latter showing more density. Chemical analysis by the scanning microanalyses revealed differences in mineral contents between: a) the external and cut surface of the outer and the invaginated enamel, and b) the external and cut surface of the normal tooth. The outer and invaginated enamels are quite different concerning the quantity and quality of minerals, the latter having no magnesium at all. Magnesium was also non existent in the dentin.

Calcium↗
PubMed2006

A qualitative X-ray analysis of white and grey mineral trioxide aggregate using compositional imaging.

Mineral trioxide aggregate (MTA) is used in endodontics as a filling and sealant material. An earlier commercial formulation Grey MTA (GMTA) was liable to became progressively discoloured, and a whiter version (WMTA) has been introduced for cosmetic reasons. This study compares the composition and particle size distribution of the two formulations using energy dispersive X-ray analysis in a scanning electron microscope. Particle size is smaller in WMTA. X-ray analysis reveals similar major peaks (calcium, silicon and bismuth) but those of the minor elements aluminium, magnesium and particularly iron are considerably less in WMTA, which may account for the colour difference. Neither contains phosphorus, a major constituent of the original formulation.

Aluminum↗
PubMed2002

Role of endocytosis in the internalization of spermidine-C(2)-BODIPY, a highly fluorescent probe of polyamine transport.

The mechanism of transmembrane polyamine internalization in mammalian cells remains unknown. A novel fluorescent spermidine conjugate [Spd-C(2)-BODIPY; N-(4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-propionyl)-N'-(S -[spermidine-(N(4)-ethyl)]thioacetyl)ethylenediamine] was synthesized from N(4)-(mercaptoethyl)spermidine by a simple, one-step coupling procedure. In Chinese-hamster ovary (CHO) cells, Spd-C(2)-BODIPY accumulation was inhibited by exogenous putrescine, spermidine and spermine, was subject to feedback transport inhibition and was up-regulated by prior polyamine depletion achieved with a biosynthetic inhibitor. Probe internalization was decreased by about 85% in a polyamine-transport-deficient CHO mutant cell line. Using confocal laser scanning fluorescence microscopy, internalized Spd-C(2)-BODIPY was concentrated in vesicle-like structures similar to the recycling endosomes observed with fluorescent transferrin, which partly co-localized with the polyamine probe. In yeast, Spd-C(2)-BODIPY uptake was stringently dependent on receptor-mediated endocytosis, as determined with a mutant defective in early- endosome formation. On the other hand, Spd-C(2)-BODIPY did not mimic the substrate behaviour of natural polyamines in yeast, as shown by the lack of correlation of its uptake characteristics with the phenotypes of mutants defective in either polyamine transport or biosynthesis. These data suggest that endocytosis might be an integral part of the mechanism of polyamine transport in mammalian cells, and that the mammalian and yeast transport systems use qualitatively different transport mechanisms. However, the current data do not rule out the possibility that sequestration of the probe into vesicular structures might be secondary to its prior uptake via a "classical" plasma membrane carrier. Spd-C(2)-BODIPY, a highly sensitive probe of polyamine transport with biochemical parameters qualitatively similar to those of natural polyamines in mammalian cells, should be very useful for dissecting the pathway responsible for polyamine internalization.

Animals↗
PubMed1986

Deposits on soft contact lenses. Electrophoresis and scanning electron microscopic examinations.

Deposits on soft contact lenses were studied by several methods, microscopic examination, scanning electron microscopy, electron microprobe and electrophoresis on polyacrylamide gels of removed proteins. The first two approaches permitted classification of deposits into globular deposits, "Mulberry-like growths", opaque deposits, protein films and red spots. The electron microprobe indicated specific compositions of each. The electrophoretic technique demonstrated the presence of lysozyme in all the deposit types, with other unidentified proteins or degradation peptides. Whatever the deposit type, heat disinfection is not advisable since proteins are always present. Combination of chelating agents and oxidizing products are logically to be preferred for cleaning lenses.

Contact Lenses, Hydrophilic↗
PubMed1995

X-ray microanalytical and morphological observations of the interface region between ceramic implant and bone.

In 8 monkeys both the maxillary lateral incisors were extracted. In the 16 extraction sites an Al2O3-ceramic dental implant (Frialit) was immediately inserted. Eight implants were submerged under the oral mucosa and the other 8 were allowed to penetrate through the mucosa during the observation period. None of the implants was loaded during the observation periods. After experimental periods of 1, 2, 4 and 8 months, the interface region between the implant and bone was examined using scanning-electron microscopy, X-ray microanalysis, back scatter, microradiography and light microscopy. The results showed that osseointegration of Al2O3-ceramic dental implant was obtained. The newly formed bone around the implant filled exactly the contours of the implant. Newly formed bone had a mineral content and a phosphorus-to-calcium ratio similar to that of the adjacent older mature jaw bone. There were no differences in the osseointegration rate between the submerged and the nonsubmerged implants. No leakage of aluminium from the implant could be detected in the bone.

Aluminum Oxide↗
PubMed1982

Healthy and diseased striated muscle studied by analytical scanning electron microscopy with special reference to fibre type.

X-ray microanalytical investigations of striated muscles in the scanning electron microscope are reviewed. The main part of the studies was performed on cryosections cut with a conventional cryostat operating at -20 degrees C to -40 degrees C. The preparation procedure including different types of attachment of the sections to the specimen holder is described in detail. The elemental changes in muscle are related to the muscle fibre type as demonstrated by histochemical methods or to histochemically demonstrated inclusions in diseased muscles. This is of great importance, because muscle disorders are often characterised by selective involvement of different muscle fibre types. The preparation methods of muscle for analytical scanning electron microscopy and the obtained results are compared with studies performed on thin cryo and epoxy sections, analysed in the transmission and scanning-transmission electron microscope. It is evident that X-ray microanalysis performed on thick cryosections provide a quick survey of the elemental composition of whole cells, and should be followed in interesting cases by close examination on the organelle level studied in thin cryosections in the transmission and scanning-transmission electron microscope.

Adenosine Triphosphatases↗
PubMed2005

The role of environmental changes on monospecies biofilm formation on root canal wall by Enterococcus faecalis.

Biofilm mode of growth is a strategy in microorganisms to survive harsh growth conditions. Although previous studies have established the ability of Enterococcus faecalis to survive postendodontic environmental conditions, the effect of such conditions on the ultrastructural and physiochemical features of E. faecalis biofilm has received less attention. This study aims to evaluate the effect of different growth conditions on the characteristics of E. faecalis biofilm on root canal, and the penetration of E. faecalis into dentinal tubules. Forty-five intact noncarious human maxillary molars were experimented under nutrient-rich, nutrient-deprived, aerobic, and anaerobic conditions for a period of 21 days. Scanning Electron Microscopy with Energy Dispersive X-ray microanalysis, Laser Confocal Scanning Microscopy and Light microscopic examinations were carried out. The microscopic analysis highlighted a distinct variation in the ultrastructure of the biofilms formed under different experimental conditions. The EDX microanalysis showed a significant increase in the levels of Calcium (Ca) in the biofilm structures formed under anaerobic nutrient-deprived condition (p < 0.001). The depth of bacterial penetration was significantly greater in nutrient-rich condition (p < 0.001). This study demonstrated distinct ultrastructural and physiochemical properties of the biofilms formed and dentinal tubular penetration of E. faecalis under different conditions.

Aerobiosis↗
PubMed2004

The application of a variable-pressure scanning electron microscope with energy dispersive X-ray microanalyser to the diagnosis of electrocution: a case report.

We describe here a case of accidental electrocution. A 48-year-old male was found dead in his room. At autopsy, there was a current mark on the right thumb and big toe. Histological examination revealed that the skin wound had the characteristics of a current mark, including vacuolation and elongation of the cell nuclei. We could also identify titanium metallization on the skin surface of the current mark using a variable-pressure scanning electron microscope (VP-SEM) equipped with energy dispersive X-ray microanalyser (EDX). The autopsy finding and the subsequent investigation support the conclusion that the cause of his death was electrocution. Our result shows that the VP-SEM with EDX is a useful tool for the forensic diagnosis of electrocution.

Accidents, Home↗
PubMed2003

[Damage of hip prosthesis causing failure in arthroplasty].

Analysis of retrieved hip joint was presented. Bone remodeling considering the distribution of friction products was discussed. Scanning electron microscopy methods were used to perform on structural analysis. We expressed a surface changing prosthetic head as Ra (roughness average). X-Ray Microanalysis was applied to study products of degradation.

Arthroplasty, Replacement, Hip↗
PubMedDate not supplied

Surface characterization of titanium-based implant materials.

This study examined the effects of different treatments (polished, electropolished, and grit-blasted) on the surface morphology and chemistry of commercially pure titanium and titanium-6% aluminum-4% vanadium. The structure and composition of the surfaces were evaluated using scanning electron microscopy, atomic force microscopy, energy dispersive spectroscopy, Auger microprobe analysis, and x-ray photoelectron spectroscopy. Surface roughness values at large scales were nearly identical for grit-blasted and electropolished samples, while at smaller scales, electropolished and polished samples had nearly identical quantitative roughness values. The surface oxide compositions were found to be primarily titanium dioxide on both materials for all surface treatments. No vanadium was seen with either x-ray photoelectron spectroscopy or Auger microprobe analysis for the alloy, indicating a possible surface depletion. Calcium was present on the grit-blasted samples, and calcium and chlorine were detected on the electropolished samples.

Alloys↗
PubMedDate not supplied

The role of analytical SEM in the determination of causation in malignant mesothelioma.

The causative relationship between asbestos exposure and mesothelioma is firmly established. Some information in this regard comes from analysis of the fiber content of lung tissue by means of analytical electron microscopy. The author has had the opportunity to study the lung asbestos content of 396 cases of mesothelioma, including 28 peritoneal cases, by means of analytical scanning electron microscopy. The highest fiber levels occurred in patients who also had asbestosis, which was found in 12% of pleural and 43% of peritoneal cases. Elevated tissue asbestos content was identified in 87% of pleural and 75% of peritoneal cases. Peritoneal cases that are asbestos related have on average a higher lung fiber burden than pleural cases. Mesotheliomas in women have elevated tissue asbestos content in about 60% of cases, and many of these had a history of exposure as a household contact of an asbestos worker. The main fiber type identified in our series was amphibole, predominantly amosite. These fibers have been demonstrated to reach the target tissue, the pleura.

Asbestos, Amosite↗
PubMedDate not supplied

Detection and qualitative identification of mineral fibers and particles in alveolar macrophages of BAL fluid by SEM and EDXA.

Inorganic dust inhalation diseases represent one of the most important chapters in respiratory medicine because of their diagnostic, therapeutic, legal, ecological and social implications. While, in fact, toxic substances inhalation may be easily related to particular occupations, it is more difficult to recognize the potential damage represented by occasional and fortuitous exposition due to pollution of one's living environment. The aim of this study was to suggest a useful investigative method for detecting the presence of mineral substances (dusts and fibers) in the lung in pulmonary fibrosis of uncertain origin. We used scanning electron microscopy (SEM) and semi-quantitative energy-dispersive x-ray microanalysis (EDXA) on broncholaveolar lavage (BAL) and sputum samples of 10 patients, all males, aged 41-66 years, smokers, affected by interstitial lung disease. Two subjects had a negative professional anamnesis while the other 8 declared a potential exposition to inorganic toxic dusts: 2 subjects were involved in the production of asbestos-containing building materials, 2 were miners, 1 a ceramic worker, and 3 insulating materials handlers. Data are reported on the detection of asbestos bodies, vitreous fibers and silica content of alveolar macrophages in BAL fluid.

Adult↗
PubMed1998

Transformation reactions of partially gold-coated bioactive Ca-P glass granules investigated by analytical scanning electron microscopy.

In the present work, we have clarified the detail of the surface transformation reactions of bioactive calcium-phosphate (Ca-P) glass granules induced by in vivo implantation in rabbit dorsal muscle sites. To this aim we have compared the behaviour, during the same implantation, between the as-prepared and gold-coated only-on-one-side glass granules. The deposited gold layer enabled us to determine very precisely the initial position of the surface of the glass before the transformation took place. In addition, since the gold layer acts as a diffusion barrier, it allowed the study of the direction and the mechanism of crystal growth which occurred at the glass surface. Lapped and polished cross-sections of the samples were examined by backscattered electron (BSE) imaging and quantitative (with standards) x-ray energy dispersive spectroscopy (EDS) in a scanning electron microscope (SEM). The observations showed the presence of an interlayered structure. Quantitative EDS microanalysis performed by profiling the electron beam across the samples indicated the presence of hydrated calcium phosphate in the external layer, an inhomogeneous silica-rich gel-type layer in the middle layer, and an unaffected original Ca-P glass in the centre. From the comparison with those granules gold-coated on one side, we deduced that the hydrated calcium phosphate layer grew towards the interior of the granules at the expense of the starting glass. A simple model, based on the balance of the concentrations of the elements which have diffused in the different layers, is proposed to explain the contribution of the elements constituting the original glass to the formation of the different layers. This result agrees with the experimental data obtained from image analysis and the microstructural behaviour of this type of glass is discussed.

Animals↗