Dentistry

Gold has been used as a delivery vehicle for various substances, for use in microscopy, and in food and liquor. 

Minute metallic gold particles are used as delivery vehicles for introduction of 

Colloidal gold was first made in the 1600s for use in microscopy. Colloidal gold particles are excellent markers in electron microscopy because they are electron-dense, spherical in shape, and can be prepared in sizes from 1 to 25 run. Colloidal gold (10 mn) is a useful tracer to obtain information about the processes involved in the immunological response. 

Aminute portion of the world s inhabitants is exposed to powdered gold (Au) as a decoration for pastries, in chocolates, or in alcoholic beverages. A rare instance of severe lichen planus in response to metallic gold dust included in a liquor is documented. 

Gold is a complex and surprisingly reactive element, with unique physical, chemical, and biochemical properties. Some of these properties are listed and discussed below. 

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Medline covers primarily biomedical literature, containing more than 13 million citations (October, 2002) of articles from more than 4600 journals published since 1958 [18]. The database covers basic biomedical research, clinical sciences, dentistry, pharmacy, veterinary medicine, pre-clinical sciences, and life science. Medline, a subset of PubMed, is a bibliographic database produced by the US Nationcil Library of Medicine (NLM). The database is available free of charge via SciFinder Scholar or PubMed [19]. 

White gold is an alloy of gold decolorized by the addition of palladium. Like gold, palladium can be beaten into leaf as thin as 1 /250,000 in. The metal is used in dentistry, watchmaking, and... 

The metal is extensively used in jewelry, wire, and vessels for laboratory use, and in many valuable instruments including therocouple elements. It is also used for electrical contacts, corrosion-resistant apparatus, and in dentistry. 

Dentistry Dentrifices Denture adhesives Denture cleaners Dentures Deodorant... 

Forensic science is an applied science having a focus on practical scientific issues that come up during criminal investigations or at trial. Some components ate unique to the field because it is conducted within the legal arena. Forensic science issues in chemistry and biochemistry in criminal investigations are discussed herein. There are a host of other forensic science areas, eg, forensic medicine, forensic dentistry, forensic anthropology, forensic psychiatry, and forensic engineering, any of which may overlap with forensic chemistry. 

Gold [7440-57-5] Au, is presumably the first metal known and used by humans. It occurs ia nature as a highly pure metal and is treasured because of its color, its extraordinary ductility, and its resistance to corrosion. Early uses ia medicine and dentistry date to the ancient Chinese and Egyptians. In the Middle Ages the demand for gold led to the iatense, unsuccesshil efforts of alchemists to convert base metals iato gold. These pursuits became the basis for chemical science. The search for gold has been an important factor ia world exploration and the development of world trade. 

Dentistry. Most casting alloys meet the composition and properties criteria of specification no. 5 of the American Dental Association (37) which prescribes four types of alloy systems constituted of gold—silver—copper with addition of platinum, palladium, and 2inc. Composition ranges are specified, as are mechanical properties and minimum fusion temperatures. Wrought alloys for plates also may include the same constituents. Similarly, specification no. 7 prescribes nickel and two types of alloys for dental wires with the same alloy constituents (see Dental materials). 

Dentistry. Mercury is used in dental amalgams for fillings in teeth (see Dental materials). Dental uses have accounted for 2—4% of total U.S. mercury consumption since 1980 and generally 3—6% before that time (3). Dental amalgams used to fill cavities in teeth are approximately 50% mercury by weight. Dental use of mercury can be expected to continue to decrease, in part because of more effective cavity prevention as well as development and increasing use of alternative dental materials such as plastics and ceramics, and increasing awareness of the environmental and health effects of mercury. 

In the x-ray portion of the spectmm, scientific CCDs have been utilized as imaging spectrometers for astronomical mapping of the sun (45), galactic diffuse x-ray background (46), and other x-ray sources. Additionally, scientific CCDs designed for x-ray detection are also used in the fields of x-ray diffraction, materials analysis, medicine, and dentistry. CCD focal planes designed for infrared photon detection have also been demonstrated in InSb (47) and HgCdTe (48) but are not available commercially. 

In dentistry, palladium alloys are widely used as alternatives to base metal alloys in the manufacture of crowns and bridges as weU as the replacement of lost or damaged teeth (see Dental materials). Such alloys contain over 80% palladium, and hence offer significant cost benefits over alloys containing a high proportion of gold. 

Zinc Oxide—Eugenol Cements. Zinc oxide—eugenol cements have many uses in dentistry. The admixture of powdered zinc oxide [1314-13-2] and Hquid eugenol [97-33-OJ, fotins a bland, easily mixed paste having exceUent working time but slow-setting characteristics. 

Although plaster has been a very successful and serviceable material, it is seriously lacking in hardness, edge strength, chip resistance, abrasion resistance, and strength to fulfiU many needs of dentistry. Some of these requirements have been partially filled by the development of the type III and type IV plasters. Table 3 Hsts the compression strength of dental plasters. 

Gold and gold alloys serve the needs of dentistry better than any other metals or alloy systems. Gold alloys have a broad range of working characteristics and physical properties, coupled with excellent resistance to tarnish and corrosion ki the mouth. 

Gold Casting and Wrought Alloys. Gold alloys useful ki dentistry may contaki gold, silver, platinum, palladium, iridium, kidium, copper, nickel, tin, kon, and zkic. Other metals occasionally are found ki minor amounts. The effect of each of the constituents is empirical, but some observations have been made. 

Platinum has many uses in dentistry. Pure platinum foil serves as the matrix in the constmction of fused-porcelain restorations. Platinum foil may be laminated with gold foil for cold-welded foil restorations. Platinum wire has found use as retention posts and pins in crown and bridge restorations. Heating elements and thermocouples in high-fusing porcelain furnaces are usually made of platinum or its alloys (see Platinum-GROUP metals). 

Palladium and Palladium Alloys. Palladium is not used in the pure state in dentistry. However, it is a usehil component of many gold casting alloys, as shown in Tables 6 and 7. 

Solders. Modem dental solders are made from mostly corrosion-resistant, nontoxic metals. Minimal quantities of tin and other elements are often added, some of which could produce toxic effects in the unalloyed state. Each solder is used for specific appHcations (180—188) typical compositions and properties of solders used in dentistry are presented in Table 11. Most of the ingredients of solders are resistant to corrosion, and alloying them with other ingredients renders the alloy safe for use in appHances placed in the oral environment. Silver solders corrode, but are used only for temporary appHances. Available products do not contain cadmium, although cadmium was an ingredient of some silver solders up to ca 1980. 

Elastomer Impression Materials. Dentistry requires impression materials that are easily handled and accurately register or reproduce the dimensions, surface details, and interrelationship of hard and soft oral tissues. Elexible, elastomeric materials are especially needed to register intraoral tooth stmctures that have undercuts. The flexibility of these elastomers allows their facile removal from undercut areas while their elasticity restores them to their original shape and size. 

Only two types of systems have found appHcation ia dentistry. Lead peroxide is the curing agent most frequently used for the polysulfide polymers that serve as dental impression materials. Lead peroxide converts the Hquid polymer to an elastic soHd within a time short enough for oral appHcations. 

Dental abrasives can be classified either according to their use or according to the degree of their abiUty to abrade (see Dentifrices). The use classification, adopted for the ADA specification no. 37 for powdered dental abrasive materials, is based on removal of stain from natural teeth or on restorations of all types. Several abrasives are used in dentistry in a variety of grit sizes and shapes. 

G. M. Biauei, ia R. B. Giaig, ed.. Polymers in Dentistry, Dental Material Reviews, Univeisity of Michigan School of Dentistiy, Ann Aiboi, Mich., 1977,... 

The addition of therapeutic or cosmetic agents to dentifrices has paralleled advances in knowledge about factors affecting the human dentition. Agents added to dentifrices can act directly on the host tooth stmcture or on specific oral accumulations, for example, the principal action of fluoride is on the tooth enamel. The primary action of an abrasive, however, is on an accumulated stained pellicle. Oral accumulations of interest to preventive dentistry are dental pellicles, dental plaque, dental calculus (tartar), microbial populations responsible for oral malodor, and oral debris (food residues, leukocytes, etc). Plaque is most important because of its potential to do harm. 

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