Dentistry, gold

The first medical application for gold was probably in dentistry. Gold wire was used to bind teeth in position 5000 years ago and bridges were first made in gold by the Romans and Etruscans over 2700 years ago. These serve to demonstrate further man s ability to manipulate and shape gold in... 

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... 

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). 

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. 

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. 

The two main uses for gold are in settling international debts and in the manufacture of jewellery, but other important uses are in dentistry, the electronics industry (corrosion-free contacts), and the aerospace industry (brazing alloys and heat reflection), while in office buildings it has... 

Hodges, R. J. The Corrosion Resistance of Gold and Base Metal Alloys , in Alternatives to Gold Alloys in Dentistry (Ed.) T. M. Valega, Sr., DHEW Publication No. (NIH) 77-1227 106-138 (1987)... 

Because of its beauty and rarity, gold bullion is still used as the international standard for money, accepted as such by all nations. It is also used in jewelry, in dentistry, and as a protective or decorative coating on the surface of other metals. Gold has even been used in space vehicles. Though men have fought and died for gold down through the centuries, the element has comparatively few uses. 

Besides the manufacture of jewellery, gold is used in electronics, dentistry, brazing alloys, the aerospace industry, etc. For several applications gold is alloyed with other metals in order to improve its mechanical properties. 

Al-Hiyasat, A. S., W. P. Saunders, S. W. Sharkey, G. McR. Smith, and W. H. Gihnonr, Investigation of human enamel wear against four dental ceramics and gold, J. Dentistry, 26, 487-495 (1998). 

Gold is also used in dentistry. This application has declined in recent years however, it still accounts for about 7% of gold consumption. Gold alloys, such as gold-silver-copper with varying amounts of platinum and... 

Amalgams. Liquid mercury is a fairly good solvent for all metals except iron and platinum. The alloys that are formed by dissolving metals in mercury are called amalgams, many of which involve inter-metallic compounds of the type MHg, where x is quite variable. Aside from their many applications in scientific work, amalgams are used in dentistry and in connection with the metallurgy of silver and gold. 

The metal finds application in photographic toning as sodium aurichloride. The chloride is employed in medicine, and in alloys in dentistry. Purple of Cassius is useful for colouring glass. Gold lace consists of a silk body with very fine strips of gold twined round the silk.1... 

The alloys of mercury are called amalgams. Amalgams of silver, gold, and tin are used in dentistry. Mercury does not wet iron, and it is usually shipped and stored in iron bottles, called flasks, which hold 76 lbs. of the metal. 

Metallic gold is used in dentistry, and gold salts still form one of the mainstays of treatment for rheumatoid... 

Dental gold alloys continue to be used and remain a source of contact hypersensitivity (7), inclnding contact stomatitis and skin eruptions at sites not nsnally associated with dentistry. Contact dermatitis to metallic gold, for example in jewellery, has also repeatedly been observed (SED-8, 510) (SEDA-22, 245). A gold surgical clip has also caused an apparently allergic reaction, characterized by sterile abscess formation (8). However, such reactions are rare and may in part be due to other metals contained in the alloy. 

Vanadium forms alloys with other metals, some of which are of considerable commercial interest. The aluminium alloys containing 10 per cent or less of vanadium are malleable, while those containing 20-25 per cent vanadium may be pulverized in water. The alloy of the composition A1V is the hardest one of the series. A copper-vanadium alloy containing 10-15 per cent vanadium, 60-70 per cent copper, 10-15 per cent aluminium, and 2-3 per cent nickel is prepared and used for the production of solid copper castings and bronzes and in the manufacture of aluminium alloys. Approximately 100 tons of cupro-vana-dium are sold annually to brass and bronze makers.1 Vanadium is also used to harden gold for use in dentistry. 

Gold is also the most ductile and malleable of all the metals. Gold is often pounded into thin leaves for decoration. One ounce of gold can be pounded flat to cover an area of 300 square feet (91.44 square meters). This ductility and resistance to corrosion—as well as its ability to reflect infrared radiation—make gold an excellent coating for space vehicles. Gold coatings are also used in dentistry... 

Gold is a precious metal that is chemically unreactive. It is used mainly in jewelry, dentistry, and electronic devices. A piece of gold ingot with a mass of 301 g has a volume of 15.6 cm. Calculate the density of gold. 

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