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PubMed2007

Hydroxyapatite/titania sol-gel coatings on titanium-zirconium alloy for biomedical applications.

A simple sol-gel method was developed for hydroxyapatite/titania (HA/TiO(2)) coatings on non-toxic titanium-zirconium (TiZr) alloy for biomedical applications. The HA/TiO(2)-coated TiZr alloy displayed excellent bioactivity when soaked in a simulated body fluid (SBF) for an appropriate period. Differential scanning calorimetry, thermogravimetric analysis, X-ray diffraction and scanning electron microscopy-energy dispersive spectrometry were used to characterize the phase transformations and the surface structures and to assess the in vitro tests. The HA/TiO(2) layers were spin-coated on the surface of TiZr alloy at a speed of 3000rpm for 15s, followed by a heat treatment at 600 degrees C for 20min in an argon atmosphere sequentially. The TiO(2) layer exhibited a cracked surface and an anatase structure and the HA layer displayed a uniform dense structure. Both the TiO(2) and HA layers were 25microm thick, and the total thickness of the HA/TiO(2) coatings was 50microm. The TiZr alloy after the above HA/TiO(2) coatings displayed excellent bone-like apatite-forming ability when soaked in SBF and can be anticipated to be a promising load-bearing implant material.

Alloys↗
PubMed2002

Scanning electron microscopy and energy-dispersive X-ray microanalysis studies of afibrillar cementum and cementicle-like structures in human teeth.

We examined afibrillar cementum (AFC) and cementicle-like structures (CLS) in human teeth by scanning electron microscopy and energy-dispersive X-ray microanalysis. The AFC showed a spur- or island-, plate- and mass-like structure with appositional laminations, while large masses in the enamel fissures enclosed CLS showing concentric appositional rings. Such AFC was observed in enamel fissures, an abnormal enamel pit, dens invaginatus and root furcations with enamel droplets, as well as on the cervical enamel surfaces, where ameloblasts are differentiated at the later or last stage of enamel formation. Cementicle-like structures were occasionally found independent from AFC and some CLS contained epithelial cell-like or ameloblast-like remnants in the core, surrounded by a few or many concentric rings. In addition, cementicles (CEC) in the root furcations also contained the remnants of Malassez's epithelial-rest cells surrounded by a few concentric rings. In some areas, AFC was mixed with enamel structures. These results show that the organic material in some parts of AFC and CLS may be derived from epithelial cells similar to that of CEC. Calcification values of AFC and CLS were significantly higher than that of fibrillar cementum, and the minute crystals are probably apatite.

Calcium Phosphates↗
PubMed1987

Microincineration and elemental X-ray microanalysis of single Bacillus cereus T spores.

Single whole spores of bacillus cereus T were analyzed by scanning electron microscopy and electron microprobe X-ray microanalysis before and after high-temperature (600 degrees C) ashing in air. High-temperature ashing consisted of a centripetal oxidation of the spore surface combined with pyrolysis of the spore's interior. Ashing of single spores produced a compact central ash particle, mimicking the much larger unashed spore body in outline but containing craterlike microregions, and a peripheral thin ash film. Ashing mostly eliminated the spore's organic matrix; however, ash residues still gave residual carbon-characteristic X-ray counts. Ashing of single spores produced a two-, five-, and six-fold increase of potassium, magnesium, and calcium X-ray intensities, respectively. Iron, although low in actual counts, became detectable after ashing. Phosphorus characteristic X-rays were decreased by 41% after ashing, while volatilization lowered sodium and manganese X-ray intensities by over 80%. High-temperature ashing enhanced element-characteristic X-ray intensities of the non-volatilizable mineral(ized) elements of spores by compacting them into ash residues, more so than by simply abolishing their organic matrix. Microincineration appears a generally useful preconcentration technique for elemental detection and localization in X-ray microanalysis.

Bacillus cereus↗
PubMed1980

Hyaline bodies of odontogenic cysts: histological, histochemical and electron microscopic studies.

Hyaline bodies of odontogenic cyst were examined by histological, histochemical and electron microscopic observations. They were seen only in odontogenic cysts and their prevalence was 6.9% in 576 cases of the cysts. They occurred most frequently within the epithelial lining, but a few bodies were observed in the connective tissue walls. Histochemical reactions of hyaline bodies were similar to those of dental cuticles, but differed from keratin. Ultrastructurally, hyaline bodies were typed into two forms: lamellated and homogeneous. The lamellated bodies were composed of alternate electron-dense and electron-lucent layers. The homogeneous bodies were occasionally formed around granular material, mineralized masses and cholesterol clefts. Hyaline bodies adjoined epithelial cells via a basal lamina-like structure and half-desmosomes. Epithelial cells containing well-developed, rough surfaced, endoplasmic reticulum were seen adjacent to hyaline bodies. Ferritin-like granules were found in the cytoplasm of epithelial cells near hyaline bodies. By electron probe X-ray microanalysis, inorganic elements within the ferritin-like granules were the same in constitution as those in the outermost electron-dense layer of the lamellated bodies. By scanning electron microscopy, hyaline bodies displayed ellipsoidal and stick-like shapes. The present study suggested that hyaline bodies are particular products formed by odontogenic epithelium.

Electron Probe Microanalysis↗
PubMed2000

In vitro bone formation on a bone-like apatite layer prepared by a biomimetic process on a bioactive glass-ceramic.

In this study we have investigated the behavior of fetal rat osteoblasts, cultured up to 23 days, on a bioactive apatite-wollastonite (AW) glass-ceramic and on the same material on which a carbonated apatite layer had been formed by a biomimetic process (AWa). At the last day of culture, the specific activity of alkaline phosphatase activity, as determined biochemically, was about 30% greater on AWa compared with AW disks. After the cell layers had been scraped off, scanning electron microscopic (SEM) observations of the materials' surfaces revealed that mineralized bone nodules remained attached to both surfaces but in larger amounts on AWa. X-ray microanalysis indicated the presence of calcium (Ca) and phosphorus (P) in the bone tissue throughout the AWa surface and Ca, P, and silicon (Si) on the AW surface. The AW/ and AWa/bone interfaces also were analyzed after fracturing of the disks. The interfacial analysis showed firm bone bonding to the AW and AWa surfaces, confirmed by the X-ray microanalytic mappings. These results indicate the importance of surface composition in supporting differentiation of osteogenic cells and the subsequent apposition of bone matrix, which allows a strong bond of the bioactive materials to the bone. Furthermore, prefabrication of a biologic apatite layer by a method that mimics biomineralization could find application to bone-repairing materials.

Alkaline Phosphatase↗
PubMed1995

Morphological effects of glycosaminoglycans on calcium oxalate monohydrate crystals.

The effects of individual glycosaminoglycan (GAG) species on calcium oxalate monohydrate (COM) crystal growth were studied in vitro by the observation of crystal morphology grown in a supersaturated calcium oxalate solution in the presence of GAGs using optical and scanning electron microscopes. GAGs affected the morphology of COM crystals differently depending on the species. The growth rates of the crystals formed in the presence of chondroitin-6-sulfate (ChS-C) were higher in length and lower in width and thickness than those of control crystals. The incorporation of dermatan sulfate or heparin into the crystals formed in the presence of these GAGs was revealed by X-ray microanalysis, whereas ChS-C was not detected in the crystals grown with it. The experiment using dicarboxylates, as a simple model of GAG molecules, showed that a distance between the side groups was important for their morphological effects. These findings suggested that the different effects of GAGs on the crystal morphology resulted from the differences in their interaction modes with COM crystal faces, that is, the differences in their binding behavior, their inhibition modes of crystal growth, and other roles played after binding to the crystals.

Calcium Oxalate↗
PubMed1993

[Corrosive changes of dental alloys in oral environment--scanning electron microscopic observation and electron probe microanalysis on crown surfaces].

In order to study the changes of the intraoral metals, the surface condition and composition of the crowns removed from mouths were analyzed by SEM and EPMA. Thirty-four samples were categorized into four types of alloys. Corrosive changes were evaluated by comparing the analysis results between the crown surface and its fresh sectioned surface, and also with the data from former studies. 1. Changes observed in the Au alloys were slight compared to the other three types, both in surface feature and composition, except for a slight decrease in Cu. 2. In some Au-Ag-Pd alloys, nearly no dissolution was evident. Composition changes were small, with a slight decrease in Ag and relative increase in Pd. 3. The greatest changes were observed in the Ag-Sn-Zn alloys and Ag-In alloys, even with short intraoral usage period. Generally, their surfaces were rough, with thick layers of organic materials. The dendritic structure was distinct, and dissolution between each dendrite was observed. 4. Many of the Ni-Cr alloys presented dendritic structure with dissolution. Decrease in Ni and relative increase in Si and Cr were observed. 5. Corrosive changes showed a close resemblance to the results obtained by the conventional basic tests. However, there were some features which did not coincide, depending on the types of alloys.

Corrosion↗
PubMed1992

Physical examination of caffeine's effects on the enamel surface of first molar in new-born rats.

Samples of the first molars of offspring whose dams were fed a diet supplemented with caffeine were examined by scanning electron microscopy, X-ray diffractometry and electron microprobe analysis. Scanning microscopy of the enamel surface of the caffeine group revealed a consistently rougher surface than in the non-caffeine controls, both before and after acid exposure. X-ray diffraction analysis of the pulverized whole tooth in the caffeine group showed broader diffraction peaks for the lattice plane reflections (202) and (300), indicating smaller crystallites. Pure enamel samples of the caffeine group examined with a Gandolfi X-ray camera also revealed more diffuse diffraction lines than in the non-caffeine controls, further indicating smaller crystallites in the enamel. The calcium and phosphorus contents of the acid-exposed samples in both control and caffeine groups were lower than the non-acid exposed control and caffeine groups by electron microprobe analysis. After exposure to acid, the calcium and phosphorus contents of the outer surface of the enamel in the caffeine group were greatly reduced as compared to that of the non-caffeine controls. Thus various methods consistently indicate that caffeine ingestion during early growth affects the enamel surface of the first molars, resulting in impaired mineralization. Caffeine intake may therefore have a negative effect on amelogenesis and possibly increases susceptibility to dental caries.

Animals↗
PubMed2006

Modified rare earth semiconductor oxide as a new nucleotide probe.

Recent rapid developments in biological analysis, medical diagnosis, pharmaceutical industry, and environmental control fuel the urgent need for recognition of particular DNA sequences from samples. Currently, DNA detection techniques use radiochemical, enzymatic, fluorescent, or electrochemiluminescent methods; however, these techniques require costly labeled DNA and highly skilled and cumbersome procedure, which prohibit any in-situ monitoring. Here, we report that hybridization of surface-immobilized single-stranded oligonucleotide on praseodymium oxide (evaluated as a biosensor surface for the first time) with complimentary strands in solution provokes a significant shift of electrical impedance curve. This shift is attributed to a change in electrical characteristics through modification of surface charge of the underlying modified praseodymium oxide upon hybridization with the complementary oligonucelotide strand. On the other hand, using a noncomplementary single strand in solution does not create an equivalent change in the impedance value. This result clearly suggests that a new and simple electrochemical technique based on the change in electrical properties of the modified praseodymium oxide semiconductor surface upon recognition and transduction of a biological event without using labeled species is revealed.

Adsorption↗
PubMed1984

Unconventional modes for STEM imaging of biological structures.

In this paper recent developments are discussed in instrumentation and methodology associated with scanning transmission electron microscopes (STEM), which are of great potential interest for solving structural and chemical problems in biological specimens. After describing the main features of the instrument, an attempt is made to define which type of signal acquisition and processing is best suited to obtain a given type of information. Starting with a definition of cross sections of interest, a discussion follows of methods using angular selection, energy selection of the transmitted beam, and several ways of signal mixing. More specific attention is devoted to two main modes of processing signals: ratio contrast, which emphasizes slight changes in scattering factors, rather independent of thickness variations; and elemental mapping, which provides semi-quantitative information on the distribution of low Z elements of great significance in biological specimens. Data relevant to typical biological objects are presented and discussed; they allow for the definition of the capabilities and limitations of these methods. These unconventional imaging modes define a new attitude for improving the efficiency of this modern generation of electron microscopes.

Animals↗
PubMed1995

[Initial corrosion of dental casting alloys in the oral environment].

In order to study the initial corrosive changes of dental casting alloys in the mouth, the condition and composition of the proximal surface of the class II inlay were analyzed by the scanning electron microscope (SEM) and the electron probe microanalyser (EPMA). These analyses on the same small areas of the proximal surface were carried out every week for four weeks. The results were compared with the condition and composition of the preplacement in the mouth, and also with the data from former studies. 1. Changes observed in the 70Au-3Pt-3Pd-10Ag-14Cu alloy (Au-alloy) were slight in comparison to the other alloys in this experiment, both on the surface condition and composition. 2. The 12Au-45Ag-20Pd-18Cu alloy (Pd-alloy) appeared to be stable in the mouth, but the changes were greater than that of the Au-alloy. 3. The Au- and the Pd-alloys appeared to be stabler after hardening heat treatment. 4. The greatest change was observed in the 65Ag-22Sn-13Zn alloy. 5. Little change was found in the 72Ni-19Cr-6Si alloy by visual inspection, but the dendritic structure was observed by SEM. 6. Almost all these changes of the alloys in this study showed somewhat greater changes than those observed in the conventional basic immersion tests of alloys.

Corrosion↗
PubMed1997

An investigation of potential desensitizing agents in the dentine disc model: a scanning electron microscopy study.

Cervical dentine sensitivity (CDS) may be defined as pain arising from exposed dentine. The prefix cervical indicates the location of the sensitivity and/or its subsequent treatment. Currently the most accepted mechanism of intradental nerve activation associated with dentine sensitivity appears to be hydrodynamic in nature. The concept of tubule occlusion as a method of dentine desensitization is a logical conclusion of the hydrodynamic theory. The authors employed the dentine disc model, qualitative scanning electron microscopy (SEM) and X-ray microanalysis to investigate whether selected desensitizing agents occlude dentinal tubule orifices. Strict control procedures have been used together with various methods of application to apply these agents to human dentine discs. SEM was used to examine the degree of deposit left by the various agents on disc surfaces and X-ray microanalysis was employed to characterize the elemental composition of the deposit. Analysis of selected agents, both prior to and after application on dentine discs was performed for comparative purposes. The degree of retention of the surface deposit upon rotation with saliva supernatant for 6 h was also studied. The results of this study indicated that ferric oxalate, the active ingredient of Sensodyne Sealant, which produced initial crystal-like structures, occluding almost all the tubule orifices was superior to potassium oxalate (Butler Protect). Of the over-the-counter (OTC) desensitizing products tested, both silica- and calcium-based abrasive components were observed both on the surface and within the tubules, indicating a certain degree of therapeutic potential for these two components. These findings suggest that certain desensitizing agents have tubule occluding properties as observed in this in vitro system which, in turn, may indicate a therapeutic potential in vivo.

Calcium↗
PubMed1991

Crystal growth on enamel in relation to acid etching.

Crystal formation may occur during etching of enamel surfaces with phosphoric acid. In this in vitro study we observed, from a morphological standpoint, some crystals left after etching, on the surfaces, using the scanning electron microscope. More often, after water-spraying, a thin generalized precipitate remains on the surface. This precipitate may be harmful for the retention of composite resins. On few specimens we obtained needle-shaped or petal-like crystals. Crystal deposits were spread evenly, on the surface, or nucleated from different points. We tempted to identify these crystal formations by X-ray diffraction and microprobe analysis. Chemical identification seems very important because calcium phosphates solubility varies. Crystal dissolution in saliva can lead to marginal leakage and impairs the quality of esthetic restorations. On the contrary insoluble crystals may ensure microscopic retentions and crystal growth is now considered as an alternative for enamel pretreatment in bracket bonding. Crystal formation, in these first experiments, is too scarce to be used for crystal bonding. But it appears that two factors may enhance the crystal number: a preliminary topical application of fluoride and adsorption of an acidic protein, on the surface, before etching. However, further investigations are still necessary.

Acid Etching, Dental↗
PubMed1982

Quantitative SEM analysis of injury to the endothelium of rabbit aorta and carotid artery during experimental atherosclerosis.

The luminal surface of the aorta and the carotid artery in normal and cholesterol-fed rabbits (3 weeks, 6 weeks, and 8 months of alimentary hypercholesterolemia) was studied by scanning electron microscopy (SEM). To study endothelial injury the vessels were perfused and stained under physiological pressure. The frequency of large and small endothelial defects was determined per surface unit of endothelium in the normal and experimental groups of rabbits. Loss of endothelial cells was regarded as a large defect, argyrophilic cells, craters, and stomata were regarded as small ones. It was found that the percentage of regions without endothelial cells was similar in both control rabbits and in rabbits with experimental atherosclerosis (0.005--0.04% of the total surface examined). The frequency of small endothelial defects increased in rabbits after 3 weeks of hypercholesterolemia but decreased to the control level after 6 weeks of hypercholesterolemia. In rabbits with 8 months of hypercholesterolemia the frequency and area of defects outside plaques did not differ from the control group. In the group with hypercholesterolemia for 8 months 39.2% of the plaque surface contained endothelial cells in which there were no distinct silver-stained cell borders. Kevex X-ray spectrometric data of silver topography indicated that the plaque surface without distinct cell borders was not an area devoid of cells. The data obtained do not support the assumption that morphological endothelial injury is the structural precursor of plaque formation.

Animals↗
PubMed1991

Bond strength with various etching times on young permanent teeth.

Tensile bond strengths of an orthodontic resin cement were compared for 15-, 30-, 60-, 90-, or 120-second etching times, with a 37% phosphoric acid solution on the enamel surfaces of young permanent teeth. Fifty extracted premolars from 9- to 16-year-old children were used for testing. An orthodontic composite resin was used to bond the bracket directly onto the buccal surface of the enamel. The tensile bond strengths were tested with an Instron machine. Bond failure interfaces between bracket bases and teeth surfaces were examined with a scanning electron microscope and calculated with mapping of energy-dispersive x-ray spectrometry. The results of tensile bond strength for 15-, 30-, 60-, or 90-second etching times were not statistically different. For the 120-second etching time, the decrease was significant. Of the bond failures, 43%-49% occurred between bracket and resin interface, 12% to 24% within the resin itself, 32%-40% between resin and tooth interface, and 0% to 4% contained enamel fragments. There was no statistical difference in percentage of bond failure interface distribution between bracket base and resin, resin and enamel, or the enamel detachment. Cohesive failure within the resin itself at the 120-second etching time was less than at other etching times, with a statistical significance. To achieve good retention, to decrease enamel loss, and to reduce moisture contamination in the clinic, as well as to save chairside time, a 15-second etching time is suggested for teenage orthodontic patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid Etching, Dental↗
PubMed1996

Bone bonding ability of an apatite-coated polymer produced using a biomimetic method: a mechanical and histological study in vivo.

A 20-microns thick apatite layer was coated onto polyethersulfone (PES) rectangular plates by soaking them in simulated body fluid containing CaO-SiO2 based glass powder. Coated and uncoated PES plates (10 x 15 x 1.5 mm) were implanted in the tibiae of rabbits, which were sacrificed 8, 16, and 30 weeks thereafter, and the samples were examined histologically using contact microradiography (CMR), Giemsa surface staining, and a scanning electron microscope connected to an electron probe microanalyzer (SEM-EPMA). The tensile failure loads at the bone/implant interfaces were determined using the detaching test. The histological examinations showed excellent bone apposition on coated PES and the sign of degradation of the apatite layer at remodeling lacunae. The apatite layer underwent complete resorption and was replaced by bone in most areas of the bone/implant interface after 30 weeks. Bone did not bond directly to uncoated PES after each follow-up period. The failure loads between bone and coated PES at 8, 16, and 30 weeks after implantation were 1.7 +/- 0.35, 2.36 +/- 0.53, and 1.45 +/- 0.48 kg, respectively. Those between bone and uncoated PES were nearly 0 kg at each postimplantation period. Failure during the detaching test occurred at the bone/apatite interface or near it after 8 weeks. After 16 weeks, it usually occurred at the apatite/ PES interface or near it, and occasionally in the middle of the apatite layer. The apatite layer was hardly detected at the failured interface after 30 weeks. In this study, an apatite-coated PES produced using a biomimetic method was demonstrated to bond directly to bone without any intervening soft tissue, which indicates that this material possesses excellent bioactivity.

Animals↗
PubMed1975

[New possibilities for demonstration of some biogenous amines in the adrenal by X-ray microanalysis (author's transl)].

Technical possibilities for the histochemical demonstration of some biogenous amines with the scanning electron-microscope and X-ray microanalysis were shown by using argentaffine and chromaffine reactions. Objects were adrenals of adult minipigs. Beside morphologic studies the amounts of silver or chromium can be determined semiquantitatively by the intensity of the specific X-radiate from "sum up-analysis" out of punctual areas. Furthermore the high amine concentrations in the adrenal medulla permit the performance of "line-analysis" and of "element-distribution-pictures" for silver or chromium. At the points chosen for analysis the concentration of epinephrine + norepinephrine is six times as high in the adrenal medulla as in the cortex; for norepinephrine alone it is only three times higher. Line-analysis shows that the concentration of katecholamines in the cortex is very low in the periphery and high near the medulla. The chromaffine reaction for serotonin leads to a distinct chromium peak in the medulla with a distribution quotient of 4.6 : 1 versus the cortex showing that there must be remarkable amounts of serotonin in the adrenal medulla, inspite of the fact that serotonin cannot by synthetized there from its natural precursor.

Adrenal Cortex↗