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Chemical tooth

Chemical interactions between the abrasive particle and the oxide surface occur and may result in highly accelerated polish rates. Ceria abrasive, for example, exhibits a chemical tooth proper-... [Pg.140]

Besides free energy of formation, several factors influence whether a given abrasive will exhibit a strong chemical tooth property. To understand these factors, we discuss the interaction of the abrasive with the oxide surface. In an aqueous solution, a SiOj... [Pg.141]

Ceria particles are considered to be one of the best glass/Si02 polishing abrasives. This is snggested to be because of the reaction between ceria and Si02 film, which resnlts in the formation of a chemical tooth between the silica surface and the ceria particles, and induced localized strain in the glass with particle... [Pg.186]

The mechanical abrasion is qualitatively described as physical tooth, whereas the adhesion or any kind of other chemical reactions between workpiece and granule can be interpreted as a chemical tooth. Often the process contains a complex mixture of actions including both kinds of tooth. ... [Pg.959]

In the case of ceria as an abrasive in contact with silica as the layer to be polished, its redox-active behaviour additionally influences the RR. This effect is called the chemical tooth . [Pg.360]

When freshly mixed, the carboxyHc acid groups convert to carboxjiates, which seems to signify chemical adhesion mainly via the calcium of the hydroxyapatite phase of tooth stmcture (32,34—39). The adhesion to dentin is reduced because there is less mineral available in this substrate, but bonding can be enhanced by the use of minerali2ing solutions (35—38). Polycarboxylate cement also adheres to stainless steel and clean alloys based on multivalent metals, but not to dental porcelain, resin-based materials, or gold alloys (28,40). It has been shown that basic calcium phosphate powders, eg, tetracalcium phosphate [1306-01-0], Ca4(P0 20, can be substituted for 2inc oxide to form strong, hydrolytically stable cements from aqueous solution of polyacids (41,42). [Pg.473]

Resins are also used for permanent tooth-colored veneers on fixed prostheses, ie, crown and bridges. Compositions for this application include acryflcs, vinyl—acryflcs, and dimethacrylates, as well as silica- or quartz-microfilled composites. The resins are placed on the metallic substrates of the prostheses and cured by heat or light. These resins are inexpensive, easy to fabricate, and can be matched to the color of tooth stmcture. Acrylic facings do not chemically adhere to the metals and are retained only by curing the resin into mechanical undercuts designed into the metal substrate. They have relatively low mechanical strength and color stability, and poor abrasion and strain resistance they also deform more under the stress of mastication than porcelain veneers or facings. [Pg.490]

Extenders are chemically inert, naturally occurring or synthetic, inorganic compounds which are included to confer specific properties to the paint. Such properties include suspending the pigment to prevent the formation of hard settlement, improvement of build , and the provision of tooth or key to improve intercoat adhesion. [Pg.586]

Suggest a reason why, when you accidentally bite on a piece of aluminum foil with a tooth containing a silver filling, you may feel pain. Write a balanced chemical equation to support your suggestion. [Pg.646]

Tykot, R.H., van der Merwe, N.J. and Hammond, N. 1996 Stable isotope analysis of bone collagen, bone apatite, and tooth enamel in the reconstruction of human diet. A case study from Cuello, Belize. In Orna, M.V., ed., Archaeological Chemistry Organic, Inorganic, and Biochemical Analysis. ACS Symposium Series 625, Washington, DC, American Chemical Society 355-365. [Pg.37]

Michel, V., Ildefonse, P. and Morin, G. 1995 Chemical and structural changes in Cervus elephus tooth enamels during fossilization (Lazaret Cave) a combined IR and XRD Rietveld analysis. Applied Geochemistry 10 145-159. [Pg.113]

Underwriters Laboratory UL 94 Standard for Safety, 11 457-458 Undifferentiated chemicals, 20 712 Undiscovered petroleum resources, 18 595 Unfilled tooth restorative resins, 8 333 Uniaxial extensional viscosity, measuring, 21 740... [Pg.983]

Ambrose, S.H. (1990). Preparation and characterization of bone and tooth collagen for isotopic analysis. Journal of Archaeological Science 17 431 451. Ambrose, S.H. (1993). Isotopic analysis of paleodiets methodological and interpretative considerations. In Investigations of Ancient Human Tissue Chemical Analysis in Anthropology, ed. Sandford, M.K., Gordon and Breach, Langhorne, pp. 59-130. [Pg.373]

Jones, A. M., Iacumin, P., and Young, E. D. (1999). High-resolution delta 0-18 analysis of tooth enamel phosphate by isotope ratio monitoring gas chromatography mass spectrometry and ultraviolet laser fluorination. Chemical Geology 153 241-248. [Pg.370]

For our day to day use, from tooth paste to TV screen or mobile battery or BMW car or aircraft to missile or anything we need are created by composite materials which we produced only by chemical processes and this stresses the service of chemistry in human endeavor. [Pg.71]

Fluorine is an essential element involved in several enzymatic reactions in various organs, it is present as a trace element in bone mineral, dentine and tooth enamel and is considered as one of the most efficient elements for the prophylaxis and treatment of dental caries. In addition to their direct effect on cell biology, fluoride ions can also modify the physico-chemical properties of materials (solubility, structure and microstructure, surface properties), resulting in indirect biological effects. The biological and physico-chemical roles of fluoride ions are the main reasons for their incorporation in biomaterials, with a pre-eminence for the biological role and often both in conjunction. This chapter focuses on fluoridated bioceramics and related materials, including cements. The specific role of fluorinated polymers and molecules will not be reviewed here. [Pg.281]


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See also in sourсe #XX -- [ Pg.467 ]




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