Aluminum Oxide: An oxide of aluminum, occurring in nature as various minerals such as bauxite, corundum, etc. It is used as an adsorbent, desiccating agent, and catalyst, and in the manufacture of dental cements and refractories.Air Abrasion, Dental: A technique using a pneumatic, high-pressure stream of aluminum oxide to remove DENTAL ENAMEL; DENTIN; and restorative materials from teeth. In contrast to using DENTAL HIGH-SPEED EQUIPMENT, this method usually requires no dental anesthesia (ANESTHESIA, DENTAL) and reduces risks of tooth chipping and microfracturing. It is used primarily for routine DENTAL CAVITY PREPARATION.Diamond: Diamond. A crystalline form of carbon that occurs as hard, colorless or tinted isomeric crystals. It is used as a precious stone, for cutting glass, and as bearings for delicate mechanisms. (From Grant & Hackh's Chemical Dictionary, 5th ed)Cladocera: A suborder of CRUSTACEA, order Diplostraca, comprising the water fleas. They are benthic filter feeders that consume PHYTOPLANKTON. The body is laterally compressed and enclosed in a bivalved carapace, from which the head extends.Aluminum Compounds: Inorganic compounds that contain aluminum as an integral part of the molecule.Aluminum Hydroxide: A compound with many biomedical applications: as a gastric antacid, an antiperspirant, in dentifrices, as an emulsifier, as an adjuvant in bacterins and vaccines, in water purification, etc.Materials Testing: The testing of materials and devices, especially those used for PROSTHESES AND IMPLANTS; SUTURES; TISSUE ADHESIVES; etc., for hardness, strength, durability, safety, efficacy, and biocompatibility.Water Quality: A rating of a body of water based on measurable physical, chemical, and biological characteristics.Dental Polishing: Creation of a smooth and glossy surface finish on a denture or amalgam.Dental Porcelain: A type of porcelain used in dental restorations, either jacket crowns or inlays, artificial teeth, or metal-ceramic crowns. It is essentially a mixture of particles of feldspar and quartz, the feldspar melting first and providing a glass matrix for the quartz. Dental porcelain is produced by mixing ceramic powder (a mixture of quartz, kaolin, pigments, opacifiers, a suitable flux, and other substances) with distilled water. (From Jablonski's Dictionary of Dentistry, 1992)Ceramics: Products made by baking or firing nonmetallic minerals (clay and similar materials). In making dental restorations or parts of restorations the material is fused porcelain. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed & Boucher's Clinical Dental Terminology, 4th ed)Porosity: Condition of having pores or open spaces. This often refers to bones, bone implants, or bone cements, but can refer to the porous state of any solid substance.Dental Bonding: An adhesion procedure for orthodontic attachments, such as plastic DENTAL CROWNS. This process usually includes the application of an adhesive material (DENTAL CEMENTS) and letting it harden in-place by light or chemical curing.Resin Cements: Dental cements composed either of polymethyl methacrylate or dimethacrylate, produced by mixing an acrylic monomer liquid with acrylic polymers and mineral fillers. The cement is insoluble in water and is thus resistant to fluids in the mouth, but is also irritating to the dental pulp. It is used chiefly as a luting agent for fabricated and temporary restorations. (Jablonski's Dictionary of Dentistry, 1992, p159)Silanes: Compounds similar to hydrocarbons in which a tetravalent silicon atom replaces the carbon atom. They are very reactive, ignite in air, and form useful derivatives.Composite Resins: Synthetic resins, containing an inert filler, that are widely used in dentistry.Surface Properties: Characteristics or attributes of the outer boundaries of objects, including molecules.Dental Stress Analysis: The description and measurement of the various factors that produce physical stress upon dental restorations, prostheses, or appliances, materials associated with them, or the natural oral structures.Metal Nanoparticles: Nanoparticles produced from metals whose uses include biosensors, optics, and catalysts. In biomedical applications the particles frequently involve the noble metals, especially gold and silver.Shear Strength: The internal resistance of a material to moving some parts of it parallel to a fixed plane, in contrast to stretching (TENSILE STRENGTH) or compression (COMPRESSIVE STRENGTH). Ionic crystals are brittle because, when subjected to shear, ions of the same charge are brought next to each other, which causes repulsion.Nitric Oxide Synthase: An NADPH-dependent enzyme that catalyzes the conversion of L-ARGININE and OXYGEN to produce CITRULLINE and NITRIC OXIDE.Microscopy, Electron, Scanning: Microscopy in which the object is examined directly by an electron beam scanning the specimen point-by-point. The image is constructed by detecting the products of specimen interactions that are projected above the plane of the sample, such as backscattered electrons. Although SCANNING TRANSMISSION ELECTRON MICROSCOPY also scans the specimen point by point with the electron beam, the image is constructed by detecting the electrons, or their interaction products that are transmitted through the sample plane, so that is a form of TRANSMISSION ELECTRON MICROSCOPY.Nitric Oxide Synthase Type II: A CALCIUM-independent subtype of nitric oxide synthase that may play a role in immune function. It is an inducible enzyme whose expression is transcriptionally regulated by a variety of CYTOKINES.Oxides: Binary compounds of oxygen containing the anion O(2-). The anion combines with metals to form alkaline oxides and non-metals to form acidic oxides.

In vitro comparison of the retention capacity of new aesthetic brackets. (1/393)

Tensile bond strength and bond failure location were evaluated in vitro for two types of aesthetic brackets (non-silanated ceramic, polycarbonate) and one stainless steel bracket, using bovine teeth as the substrate and diacrylate resin as the adhesive. The results show that metallic bracket had the highest bond strength (13.21 N) followed by the new plastic bracket (12.01 N), which does not require the use of a primer. The non-silanated ceramic bracket produced the lowest bond strength (8.88 N). Bond failures occurred mainly between bracket and cement, although a small percentage occurred between the enamel-cement interface with the metal and plastic brackets and within the cement for the plastic bracket. With the ceramic bracket all the failures occurred at the bracket-cement interface. This suggests that the problems of enamel lesions produced by this type of bracket may have been eliminated. The results also show that the enamel/adhesive bond is stronger than the adhesive/bracket bond in this in vitro study.  (+info)

Effects of magnesia and potassium sulfate on gypsum-bonded alumina dental investment for high-fusing casting. (2/393)

The purpose of this study was to improve the characteristics of gypsum-bonded alumina investments using magnesia and potassium sulfate as chemical additives. Magnesia content improved fluidity, delayed setting reaction, increased green strength, and decreased setting expansion, when mixed with distilled water. When the investment was mixed with potassium sulfate, the setting time and setting expansion were reduced, and the thermal expansion increased, however, the green strength decreased. Therefore, the investment with a small amount of magnesia mixed with potassium sulfate was considered a suitable composition, having adequate setting behavior, enough green strength and sufficient compensate expansion for casting.  (+info)

Thermal image analysis of electrothermal debonding of ceramic brackets: an in vitro study. (3/393)

This study used modern thermal imaging techniques to investigate the temperature rise induced at the pulpal well during thermal debonding of ceramic brackets. Ceramic brackets were debonded from vertically sectioned premolar teeth using an electrothermal debonding unit. Ten teeth were debonded at the end of a single 3-second heating cycle. For a further group of 10 teeth, the bracket and heating element were left in contact with the tooth during the 3-second heating cycle and the 6-second cooling cycle. The average pulpal wall temperature increase for the teeth debonded at the end of the 3-second heating cycle was 16.8 degrees C. When the heating element and bracket remained in contact with the tooth during the 6-second cooling cycle an average temperature increase of 45.6 degrees C was recorded.  (+info)

Super pulse CO2 laser for bracket bonding and debonding. (4/393)

A super pulse and a normal pulse CO2 laser were used to carry out enamel etching and bracket debonding in vitro and in vivo. The shear bond strength of the orthodontic brackets attached to laser-etched and conventional chemically-etched extracted premolars was measured. The pulp cavity temperature was also measured using the same laser irradiation conditions as the shear test. Both super pulse and normal pulse CO2 laser etching resulted in a lower shear bond strength (super pulse: 6.9 +/- 3.4 kg, normal pulse: 9.7 +/- 5.2 kg) than that of chemical etching (15.3 +/- 2.8 kg). Furthermore, the super pulse CO2 laser was able to create debonding at 2 watts within a period of less than 4 seconds (2.9 +/- 0.9 seconds). The super pulse, when irradiating the ceramic brackets from above, during debonding showed a 1.4 degrees C temperature increase in the dental pulp at 2 watts and an increase of 2.1 degrees C at 3 watts. While etching, directly irradiating the enamel surface at 3 watts, the dental pulp showed a temperature increase of 3.5 degrees C. These temperature increases were within the physiologically acceptable limits of the pulp. These results indicate that, in orthodontic treatments, super pulse CO2 laser debonding is more useful than laser etching.  (+info)

A laboratory investigation to compare enamel preparation by sandblasting or acid etching prior to bracket bonding. (5/393)

A laboratory investigation to compare the mean shear debonding force and mode of bond failure of metallic brackets bonded to sandblasted and acid-etched enamel is described. The buccal surfaces of 30 extracted human premolars were sandblasted for 5 seconds with 50 mu alumina and the buccal surfaces of a further 30 human premolars were etched with 37 per cent phosphoric acid for 15 seconds. Following storage for 24 hours at 37 degrees C in distilled water, shear debonding force was measured using an Instron Universal Testing Machine with a cross-head speed of 10 mm/minute. Mean shear debonding force was significantly lower for brackets bonded to sandblasted enamel compared to acid etched enamel (P < 0.001). Weibull analysis showed that at a given stress the probability of failure was significantly greater for brackets bonded to sandblasted enamel. Brackets bonded to etched enamel showed a mixed mode of bond failure whereas following sandblasting, failure was adhesive at the enamel/composite interface (P < 0.01).  (+info)

Respiratory symptoms and lung function in alumina refinery employees. (6/393)

OBJECTIVES: Employees in alumina refineries are known to be exposed to a number of potential respiratory irritants, particularly caustic mist and bauxite and alumina dusts. To examine the prevalence of work related respiratory symptoms and lung function in alumina refinery employees and relate these to their jobs. METHODS: 2964 current employees of three alumina refineries in Western Australia were invited to participate in a cross sectional study, and 89% responded. Subjects were given a questionnaire on respiratory symptoms, smoking, and occupations with additional questions on temporal relations between respiratory symptoms and work. Forced expiratory volume in 1 second (FEV(1)) and forced vital capacity (FVC) were measured with a rolling seal spirometer. Atopy was assessed with prick skin tests for common allergens. Associations between work and symptoms were assessed with Cox's regression to estimate prevalence ratios, and between work and lung function with linear regression. RESULTS: Work related wheeze, chest tightness, shortness of breath, and rhinitis were reported by 5.0%, 3.5%, 2.5%, and 9.5% of participants respectively. After adjustment for age, smoking, and atopy, most groups of production employees reported a greater prevalence of work related symptoms than did office employees. After adjustment for age, smoking, height, and atopy, subjects reporting work related wheeze, chest tightness, and shortness of breath had significantly lower mean levels of FEV(1) (186, 162, and 272 ml respectively) than subjects without these symptoms. Prevalence of most work related symptoms was higher at refinery 2 than at the other two refineries, but subjects at this refinery had an adjusted mean FEV(1) >60 ml higher than the others. Significant differences in FVC and FEV(1)/FVC ratio, but not FEV(1), were found between different process groups. CONCLUSIONS: There were significant differences in work related symptoms and lung function between process groups and refineries, but these were mostly not consistent. Undefined selection factors and underlying population differences may account for some of these findings but workplace exposures may also contribute. The differences identified between groups were unlikely to be clinically of note.  (+info)

Extensive metallosis and necrosis in failed prostheses with cemented titanium-alloy stems and ceramic heads. (7/393)

We describe three prostheses with cemented titanium-alloy stems and Al2O3 ceramic femoral heads which had to be revised after a mean period of implantation of 78 months. In each case, the neck of the prosthesis had been so severely worn that the profile was elliptical rather than circular. There was severe metallosis of the periprosthetic tissues. Metal particles isolated from the tissues were approximately one nanometre in size and the ratios of titanium, aluminium and vanadium in the particles were the same as in the original alloy. Histologically, the high concentration of metal particles masked the presence of high-density polyethylene (HDP) debris, but again particles about one nanometre in size were isolated from the tissues. The severe necrobiosis and necrosis noted were consistent with other reports of the presence of extensive wear particles in periprosthetic tissues. Wear is presumed to have occurred as a result of mismatch between the shape or size of the taper cone and the femoral head, or to changes in the geometry of loading due to migration of the cup. To facilitate early intervention, patients with this design of prosthesis should be monitored radiologically.  (+info)

Cytotoxicity and macrophage cytokine release induced by ceramic and polyethylene particles in vitro. (8/393)

Although the response of macrophages to polyethylene debris has been widely studied, it has never been compared with the cellular response to ceramic debris. Our aim was to investigate the cytotoxicity of ceramic particles (Al2O3 and ZrO2) and to analyse their ability to stimulate the release of inflammatory mediators compared with that of high-density polyethylene particles (HDP). We analysed the effects of particle size, concentration and composition using an in vitro model. The J774 mouse macrophage cell line was exposed to commercial particles in the phagocytosable range (up to 4.5 microns). Al2O3 was compared with ZrO2 at 0.6 micron and with HDP at 4.5 microns. Cytotoxicity tests were performed using flow cytometry and macrophage cytokine release was measured by ELISA. Cell mortality increased with the size and concentration of Al2O3 particles. When comparing Al2O3 and ZrO2 at 0.6 micron, we did not detect any significant difference at the concentrations analysed (up to 2500 particles per macrophage), and mortality remained very low (less than 10%). Release of TNF-alpha also increased with the size and concentration of Al2O3 particles, reaching 195% of control (165 pg/ml v 84 pg/ml) at 2.4 microns and 350 particles per cell (p < 0.05). Release of TNF-alpha was higher with HDP than with Al2O3 particles at 4.5 microns. However, we did not detect any significant difference in the release of TNF-alpha between Al2O3 and ZrO2 at 0.6 micron (p > 0.05). We saw no evidence of release of interleukin-1 alpha or interleukin-1 beta after exposure to ceramic or HDP particles.  (+info)

  • Aluminum oxide (Al2O3), more commonly known as alumina, is extensive used in a variety of industrial manufacturing applications and various engineering processes. (
  • abstract = "Specific features are studied of combustion of mixtures of the industrial aluminum powders ASD-1 and ASD-4 with superfine powders of Al and γ-Al2O3 in air. (
  • When occurring as crystalline form, aluminum oxide most closely resembles properties of natural corundum, with the characteristic property of remarkable hardness. (
  • Songshan Specialty Materials, Inc. is one of the largest manufacturers of Brown Aluminum Oxide in China, having 8 sets of 4000KVA furnaces (4 tilting furnaces and 4 batch furnaces) and 3 large grain lines. (
  • This report was a professional and depth research report on Global Aluminum oxide industry that you would know the world's major regional market conditions of Aluminum oxide industry, the main region including North American, Europe and Asia etc, and the main country including United States ,Germany ,Japan and China etc. (
  • A major chunk of the consumption of aluminum oxide materials comes from countries such as India and China. (
  • 2014 Market Research Report on Global Aluminum oxide Industry is a new market research publication announced by Reportstack. (
  • In the end, the report introduced Aluminum oxide new project SWOT analysis, investment feasibility analysis, and investment return analysis and Global Aluminum oxide industry. (
  • In a word, it was a depth research report on Global Aluminum oxide industry. (
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  • 97, 8495 ( 1993) D. Routkevitch, T. Bigioni, M. Moskovits, J. M. Xu, Electrochemical Fabrication of CdS Nano-Wire Arrays in Porous Anodic Aluminum Oxide Templates, J. Phys. (
  • with Nano-alumina has good properties of heat insulation,insulation and high security. (
  • 2. Adulterating nano aluminum in LiCoO2 can form a solid solution, stabilize lattice and increase its rate capability and cycling. (
  • Magnetic alumina nano composite (MANC) was prepared for combination of the adsorption features of nano activated alumina with the magnetic properties of iron oxides to produce a nano magnetic adsorbent, which can be separated from the medium by a simple magnetic process after adsorption. (
  • The patent in suit concerns aluminum oxide particles and a polishing composition containing the same. (
  • In its decision, the opposition division dealt with the ground for opposition pursuant to Article 100(b) EPC and found that the invention was not sufficiently disclosed because how to obtain the claimed aluminum oxide particles was not known. (
  • 1. Aluminum oxide particles characterized by primary particles each having a hexahedral shape and an aspect ratio of 1 to 5. (
  • It was common ground between the parties that the claimed aluminum oxide particles could be produced by calcining a hydrated alumina having the claimed morphology and aspect ratio, the morphology and aspect ratio of said hydrated alumina used as raw material being maintained during the calcination (paragraph of the patent in suit). (
  • A chemical vapor deposition process for laying down an aluminum oxide coating on a glass substrate through the use of an organic ester having a β hydrogen on the alkyl group bonded to the carboxylate oxygen and an inorganic aluminum halide. (
  • 2. The process for depositing the aluminum oxide coating on the substrate as recited in claim 1 , wherein said ester is selected from the group consisting of ethyl formate, ethyl acetate, ethyl propionate, isopropyl formate, isopropyl acetate, n-butyl acetate, and t-butyl acetate. (
  • 3. The process for depositing the aluminum oxide coating on a glass substrate as recited in claim 2 , wherein the ester in the precursor gas mixture is at a concentration of about 1 to 9 times the concentration of the aluminum halide. (
  • 4. The process for depositing the aluminum oxide coating on the glass substrate as recited in claim 1 , wherein said inorganic aluminum halide is an inorganic aluminum chloride. (
  • 6. The process for depositing the aluminum oxide coating on the substrate as recited in claim 1 , wherein the substrate is a float glass ribbon. (
  • 7. The process for depositing the aluminum oxide coating on the substrate recited in claim 6 , wherein the precursor gas mixture flows over the float glass ribbon to be coated under laminar flow conditions. (
  • 8. The process for depositing the aluminum oxide coating on a substrate as recited in claim 6 , wherein said float glass ribbon is at a temperature in the range of about 1100 -1320 F./590 C.-715 C. (
  • 10. The process for depositing the aluminum oxide coating on the substrate as recited in claim 1 , wherein the substrate has a silica coating thereon, and said aluminum oxide coating is deposited over the silica coating. (
  • 12. The process for depositing the aluminum oxide coating on the glass substrate as recited in claim 1 , wherein said aluminum oxide coating has an average refractive index of about 1.5-1.65 in the 400 to 800 nm range of the electromagnetic spectrum. (
  • 13. The process for depositing the aluminum oxide coating on the glass substrate as recited in claim 1 , wherein said deposition process results in a deposition rate of 200 Å/sec. or more. (
  • Subsequently, at least some of the evaporated aluminum oxide and silicon monoxide is deposited on a substrate to form the silicon-doped aluminum oxide on the substrate. (
  • To make the sensor, the researchers begin by using a technique called atomic layer deposition to produce a very thin film of aluminum oxide on a silicon substrate. (
  • Smelting is a chemical process, by which metal ores, or rather the metal ions in metal ores , are reduced (gain electrons) to the pure metal . (
  • The effect of aluminum doping ratio in AZO nanoparticles (based on Al-nitrate precursor) on structure, phase composition, and particle size has been investigated. (
  • The aluminum-oxide nanopore sensors go a step further," Bashir said, "exhibiting superior mechanical properties, enhanced noise performance and increased lifetime over their silicon-oxide and silicon-nitride counterparts. (
  • For special grades of isopressed alumina for plain and metallized tubes see our ISO ALUMINA Data Sheet and for very large gel cast shapes and ultra high purity (99.99%) see our REPTON and SEMICONDUCTOR pages. (
  • Y. Xu and L. Axe, "Synthesis and Characterization of Iron Oxide-Coated Silica and Its Effect on Metal Adsorption," Journal of Colloid and Interface Science, Vol. 282, No. 1, 2005, pp. 11-19. (
  • Angular shape makes this aluminum oxide blast media the longest-lasting rust-removing media. (
  • One of the drawbacks of methanol as a fuel is its corrosivity to some metals, including aluminum. (
  • Norton aluminum oxide bench and pedestal grinding wheels are used for offhand deburring, sharpening, shaping and limited stock removal on all types of metals. (
  • Our 952 aluminum oxide grinding stone features a high-quality industrial abrasive that's perfect for extended general-purpose grinding on metals, castings, welded joints, rivets and rust. (
  • Nanoporous AAO is formed by electrochemical oxidation (anodization) of aluminum in liquid electrolytes in the conditions that balance the growth and the localized dissolution of aluminum oxide to form arrays of nanopores. (
  • A thin layer of alumina will form on any exposed aluminum surface and protects it from further oxidation. (
  • Three related conversion coating methods are described that are based on film formation which occurs when aluminum alloys are exposed to alkaline Li salt solutions. (
  • Under aqueous conditions, basic aluminum oxide plates are best for separating basic compounds, while neutral plates are ideal for separating neutral compounds. (
  • Based upon observed tribological mechanics a model has been developed to describe thermo-mechanical behavior of oxide aluminum-chrome carbide composition under friction. (
  • INVENToRSI WALTER GEFFLKENQMMA FMILSTlCH X w W W L ATTORNEYS niteci States The present invention relates to a glass composition containing lanthanum borosilicate and being rich in aluminum oxide. (
  • introducing the precursor gas mixture into the coating chamber, whereby the gaseous mixture is heated to above the reaction temperature of the aluminum halide and the ester and incorporates oxygen from the ester to cause the deposition of the aluminum oxide coating. (
  • The resulting article has an aluminum oxide coating which can be of substantial thickness because of the high deposition rates attainable with the novel process. (