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PubMed1999

Evaluation of bone tissue on metallic implants by energy-dispersive x-ray analysis: an experimental study.

Osseointegration capacity of the different metallic implants depends on several variables. Osseointegration can be evaluated by using different methodologies, such as light microscopy and scanning or transmission electron microscopy. The aim of this study was to develop a qualitative and quantitative method to evaluate the presence of bone tissue on large metallic surfaces. A laminar implant was placed in each tibia of 10 Wistar rats. The animals were killed 30 days after surgery. Tibiae were resected, one for embedding in methyl methacrylate and the other for evaluation by energy-dispersive x-ray analysis. Light microscopy revealed osseointegration. Observation of the implant surface by scanning electron microscopy revealed the presence of a coating on the metallic surface that was rough in some areas and smooth in others. Analysis of the coating by energy-dispersive x-ray analysis showed the presence of Ca and P. Eighty percent (+/- 10%) of the metallic implant surface exhibited bone tissue. After confirmation of the occurrence of osseointegration capacity using light microscopy, the method described here allows qualitative and quantitative evaluation of the bone tissue found on large metallic surfaces.

Animals↗
PubMed2004

Comparison of the mechanical properties of 2 prosthetic mini-implants.

Two prosthetic mini-implants (MTI and MDI), which have very similar shapes, are widely used. In this investigation, the mechanical and physical properties of 2 prosthetic mini-implants were investigated. The flexural properties were measured with a universal testing machine. The surface image was observed by SEM with EDX. X-ray analyses were performed. The maximum strength and proportion limit for the different implants differed significantly (P <0.01); however, elastic modulus did not differ significantly (P >0.01). Although the surface of the MTI was smooth, the MDI had a rough surface. The elemental analysis detected titanium (Ti) in the MTI, and Ti, aluminum, and vanadium in the MDI. From the x-ray diffraction pattern, the MTI, which is composed of pure titanium, had a narrow, sharp Ti (syn) peak, whereas the corresponding peak for the MDI was small and broad. Although the 2 devices have similar shapes and dimensions, their surfaces and mechanical properties differ greatly. MTI is easy to remove and wrought in clinical use, and MDI is excellent in flexural properties compared with MTI. (Implant Dent 2004;13:251-256)

Aluminum↗
PubMedDate not supplied

Photolytically driven generation of dissolved oxygen and increased oxyhemoglobin in whole blood.

The severely debilitating nature of chronic lung disease has long provided the impetus for the development of technologies to supplement the respiratory capacity of the human lung. Although conventional artificial lung technologies function by delivering pressurized oxygen to the blood through a system of hollow fibers or tubes, our approach uses photolytic energy to generate dissolved oxygen (DO) from the water already present in blood, thus eliminating the need for gas delivery. We have previously demonstrated that it is feasible to generate dissolved oxygen from water based on UVA illumination of a highly absorbent TiO2 thin film. In the current study, we extend this work by using photolytic energy to generate DO from whole blood, thus resulting in an increase of oxyhemoglobin as a function of back side TiO2 surface film illumination. Initial experiments, performed with Locke's Ringer solution, demonstrated effective film thickness and material selection for the conductive layer. The application of a small bias voltage was used to conduct photogenerated electrons from the aqueous phase to minimize electron recombination with the DO.Mixed arterial-venous bovine blood was flowed in a recirculating loop over TiO2 nanocrystalline films illuminated on the side opposite the blood (or "back side") to eliminate the possibility of any direct exposure of blood to light. After light exposure of the TiO2 film, the fraction of oxyhemoglobin in the blood rapidly increased to near saturation and remained stable throughout the trial period. Last, we evaluated potential biofouling of the DO generating surface by scanning electron microscopy, after photolytically energized DO generation in whole blood, and observed no white or red blood cell surface deposition, nor the accumulation of any other material at this magnification. We conclude that it is feasible to photolytically oxygenate the hemoglobin contained in whole blood with oxygen derived from the blood's own water content without involving a gaseous phase.

Animals↗
PubMed1991

Permeability of dormant spores of Bacillus subtilis to malachite green and crystal violet.

The permeability of dormant spores of Bacillus subtilis to malachite green (MG) and crystal violet (CV) was examined by using potassium trichloro(eta 2-ethylene)platinum(II) (KTPt) as an electron-opaque marker for the dyes. The spores were treated with the dyes and other substances at 30 degrees C for 30 min or at 80 degrees C for 5 min. When the spores were incubated in 50 mM-MG solution at 30 degrees C and in 50 mM-CV solution at 30 degrees C or 80 degrees C, many small electron-dense precipitates, which were chemical complexes of dyes and platinum, were seen, mainly around the boundary between the inner and outer coat regions. The spores treated under the above conditions were not stained. Treatment with 50 mM-MG alone or a mixture of 25 mM-oxalic acid and 50 mM-CV at 80 degrees C made the spores stainable and dye-TPt precipitates were observed mainly in the outer pericortex region. Pretreatment with 25 mM-oxalic acid and 5% (v/v) phenol at 80 degrees C followed by 50 mM-CV treatment at 30 degrees C gave the same results as above. It was considered from these results that the inner coat itself might function as the primary permeability barrier to MG and CV, and that a secondary barrier to the dyes might exist around the cortex region.

Bacillus subtilis↗
PubMed1984

The pathogenesis of amiodarone-induced pigmentation and photosensitivity.

A new method has been used to measure tissue levels of amiodarone and its major metabolite desethylamiodarone. Amiodarone-pigmented skin has a drug and metabolite concentration ten times that of non-pigmented skin. Iodine-rich amiodarone and its metabolite have been detected in secondary lysosomes by energy dispersive analysis of X-rays. Amiodarone induces a phototoxic reaction with an action spectrum in both the UV-B and UV-A wavelengths.

Adult↗
PubMed2006

Influence of sodium hypochlorite on fracture properties and corrosion of ProTaper Rotary instruments.

AIM: To evaluate the influence of immersion in NaOCl on resistance to cyclic fatigue fracture and corrosion of ProTaper NiTi Rotary instruments. METHODOLOGY: A total of 120 new ProTaper NiTi Rotary files (F2) were randomized and assigned to three different groups of 40 each. Group 1 was the control group; 20 mm (excluding the shaft) of group 2 instruments were immersed in 5% NaOCl at 50 degrees C for 5 min; instruments in group 3 were completely immersed in 5% NaOCl at 50 degrees C for 5 min. All instruments were then tested for cyclic fatigue, recording the time in seconds to fracture. Data were analysed by the Kruskall-Wallis test and post-hoc multiple comparisons (P < 0.05). Micromorphological and microchemical analyses were also completed by means of a field emission scanning electron microscopy (SEM) on those instruments in group 3 that had undergone early fracture. RESULTS: Instruments in group 3 had a significantly lower resistance to fracture because of cyclic fatigue than those in groups 1 and 2 (P < 0.001). In some instruments in group 3, early fracture occurred after only a few seconds of fatigue testing. SEM observations revealed evident signs of corrosion of the fractured instruments. CONCLUSION: Group 3 had significantly reduced resistance to cyclic fatigue compared with instruments in groups 1 and 2. The phenomenon of early fracture may be attributed to galvanic corrosion induced by the presence of dissimilar metals, where one acts as the cathode of a galvanic couple, established when the instrument is immersed in NaOCl solution. The NiTi alloy may acts as the anode and thus undergoes corrosion.

Corrosion↗
PubMed1984

Ultrastructural comparison of ion beam and radiofrequency plasma etching effects on biological tissue sections.

Three dry etching techniques (Ar+ ion beam, O2+ ion beam, O2 radiofrequency electrodeless discharge) were compared with respect to preferential etching and damage to the ultrastructure of glutaraldehyde-fixed Epon-embedded frog skeletal muscle sections. SEM and TEM studies were performed on both unstained and stained (osmium tetroxide, uranyl acetate) sections. Etching effects were observed to differ for the various ion beam or plasma etching techniques. Whereas selective retention of electron dense structures (e.g. Z lines, nuclear heterochromatin) was observed for oxygen plasma etching, preferential etching of these components was observed using O2+ ion beam bombardment. Selectively etched Z lines and etch-resistant nucleoli were observed for both reactive (O2+) and inert (Ar+) ion beam sputtering after sufficiently high ion doses. The above suggest that selective etching under keV ion beam irradiation is related more to physical sputtering processes (momentum transfer) than to the chemical reactivity of the incident ion. Heavy metal post-fixation and staining had no qualitative effect on the nature of the selective etching phenomena. The above findings are significant in that they potentially influence both electron and ion microprobe measurements of etched biological specimens.

Animals↗
PubMed1992

Characterization of inorganic fillers in visible-light-cured dental composite resins.

Inorganic fillers in seven visible-light (VL)-cured dental composite resins were examined for their size, composition, phase and content, employing the following analytical instruments. SEM observations indicated that five samples could be classified into the hybrid type while the remaining two belonged to micro-filled and sub-micron types. EDX analyses revealed that five samples contained BaO while others lacked BaO. XRD analyses showed that three were in vitreous phase, two were in the crystalline phase and two were mixtures of both. DTG thermal analyses indicated that the hybrid type composites had the higher inorganic filler content (wt%) than the composites of two other types. In conclusion, wide varieties exist in the inorganic fillers in VL-cured dental composite resins currently utilized.

Aluminum Oxide↗
PubMed1995

X-ray microprobe analysis of corpora amylacea.

Since corpora amylacea is concentrated in the high density fraction in the subcellular fractionation of autopsy brain. It is suspected that inorganic materials accumulate in corpora amylacea. Therefore, elemental analyses of partially purified corpora amylacea from autopsy brain from a patient with Alzheimer's disease and those from brain of a non-demented patient were performed by the X-ray microprobe method. Prominent peaks of sodium, phosphorus, sulphur and chloride were observed, and mapping analyses confirmed that these elements were actually contained within the corpora amylacea. A similar result was obtained using cryostat sections. Corpora amylacea are characteristically distributed along the margin of blood vessels, beneath the pial border of the hippocampus and in the subependymal zones of ventricles of aged brains, namely in the vicinity of blood and cerebrospinal fluid. From this distribution and from the results of the present paper, we suggest that corpora amylacea play a role in the absorption and accumulation of inorganic materials which have been extravasated from blood and cerebrospinal fluid (CSF) and taken up by astrocytes. This may reflect alteration of the blood-brain and blood-CSF barriers in the ageing brain.

Alzheimer Disease↗
PubMed1995

Effects of citric acid treatment on the Ca, P and Mg contents of human dental roots.

An electron microprobe analyser associated with a scanning electronic microscope was used to measure Ca, P and Mg contents of the human dental root hard tissues, before and after a citric acid treatment (pH = 1). The measurements were made on transverse sections through the cervical 1/3 of the molar roots. The measurements were performed at the following 8 levels: the internal cementum, the cementum-dentine junction, cementum-related dentine, 4 external dentine levels located at 220 microns, 420 microns, 620 microns and 820 microns from the cementum-dentine junction, and finally the juxta-pulpal dentine. After the citric acid treatment, the losses in Ca and P, but not in Mg, varied significantly with the level; an acid-resistant dentine layer of approximately 600 microns was found under the cementum-dentine junction. An increase in the Ca/P ratio was also observed in this layer. Since this external dentine zone is less demineralized by the citric acid than the underlying dentine, the collagen matrix in this region may also be less exposed. These differences in the response to citric acid that depend on the distance from the root surface may explain the unpredictability of periodontal healing after citric acid treatment of diseased root surfaces, because the amount of tissue removed during root planing is not constant.

Calcium↗
PubMed2006

Lymphocytoma cutis due to pierced earrings.

We report two cases of lymphocytoma cutis caused by pierced earrings, with the results of patch tests and X-ray microanalyses on electron microscopy. We detected zinc through scanning electron microscopy from the specimen of Case 1 and gold and titanium through transmission electron microscopy from Case 2. This is the first report to demonstrate the presence of metal fragments in the lesion, which may suggest the remanence of metal for 20 years, bringing about persistent allergic reaction.

Adult↗
PubMed1986

Scanning electron microscope and electron microprobe study of reactions of stannous fluoride and stannous chloride with dental enamel.

Stannous fluoride but not stannous chloride has shown a caries inhibiting effect in animal studies. The effect of aqueous solutions of stannous fluoride and stannous chloride on dental enamel surfaces was investigated by scanning electron microscope and analytical electron microprobe. Some large globules and a continuous layer of small globules were observed after stannous fluoride treatment. The large globules were soluble in both water and alkali, whereas the small ones were only soluble in alkali. Both fluoride and tin were found to be present on the enamel surfaces by the electron microprobe after stannous fluoride treatment. The fluoride could not be detected after immersion in distilled water whereas alkali treatment removed the tin. The large fluoride-containing globules may consist of calcium fluoride as this substance is known to be slightly soluble in water and soluble in alkali. Stannous chloride treatment gave a layer of small tin-containing globules with properties similar to the layer formed on enamel treated with stannous fluoride. It is therefore suggested that the tin-containing layer is not associated with caries protection whereas calcium fluoride-like deposition on the enamel probably is a factor in the caries inhibition caused by stannous fluoride.

Dental Enamel↗
PubMed1987

Treatment of dentin with stannous fluoride--SEM and electron microprobe study.

The effect of SnF2-treatment of dentin surfaces was investigated by means of scanning electron microscopy (SEM) and electron microprobe analysis. Human dentin was treated with aqueous SnF2 solutions of concentrations varying from 1 to 10%. The treatment periods lasted for 1, 5, 10, or 60 min. Both tin and fluoride were identified on the surfaces. The concentration varied depending on the extensiveness of the treatment. Immersion in 1 M KOH for 15 h removed both tin and fluoride from the surfaces. This reaction was not observed after immersion in H2O for the same time period. Examination of the SnF2-treated dentin surfaces showed a dense layer of globular particles and in addition some larger particles. The dentinal tubules were totally covered even after the treatment with the lowest concentration of SnF2. Deposition of tin- and fluoride-containing globules on dentin surfaces may be of clinical interest. This layer may have importance both for the caries resistance of dentin and for hypersensitivity reactions.

Dental Caries↗
PubMed1993

Analytical electron microscopy of chlorhexidine-induced tooth stain in humans: direct evidence for metal-induced stain.

Using analytical electron microscopy, we directly tested the hypothesis that transition metals and sulfur are the cause of chlorhexidine-induced tooth stain. Plaque scraped from the teeth of water-treated individuals or chlorhexidine-treated "non-stainers" was non- or lightly-stained and contained low concentrations of sulfur and transition metals. Tooth scrapings from heavily-staining chlorhexidine-treated individuals consisted of distinct unstained and stained regions. The stained regions were organic but were in close proximity to mineralized areas. Enhanced levels of sulfur and transition metals, particularly iron, were found in stained regions, whereas unstained regions contained low sulfur and metal levels similar to the water-treated or non-staining individuals. Excluding decreased mineralization, the major elemental change in heavily-stained plaque was an increase in sulfur, and to a lesser extent, iron and other transition metals. Sulphur and iron levels were directly correlated. Following chlorhexidine treatment with iron supplementation, staining was enhanced, the Fe/S ratio increased, and sulfur and iron remained correlated. These data support the hypothesis that transition metals and sulfur are the cause of chlorhexidine-induced tooth stain. The data are consistent with chlorhexidine treatment altering the incorporation into plaque of a natural sulfur-containing organic component of saliva or bacteria. This natural component appears to readily interact with transition metals, particularly iron, producing stained material.

Chlorhexidine↗