Dental amalgams corroded the most but the tarnish experience depended more on their chemistry than their precious metal composition. L. Laub, J. Stanford Tarnish and corrosion behaviour of dental gold alloys, Gold Bulletin 1981, 14 (1) [12] J. Geis-Gerstorfer, H. Weber In vitro corrosion behavior of four Ni-Cr dental alloys in lactic acid and sodium chloride solutions, Dent. 2. Tarnish is a surface discoloration of the metal or even a slight loss of the luster. Dentistry. As erosion in dentistry is related to a chemical dissolution of hard dental tissues, corrosion instead of erosion will be used to describe chemical or electrochemical changes of dental materials in the oral cavity environment. WARNING: WITHDRAWN Standard. 3. Information on methods available for the determination of tarnish and corrosion of metals and alloys: Status: Superseded, Withdrawn: Publication Date: 15 December 1993: Withdrawn Date: 15 August 2001: Normative References(Required to achieve compliance to this standard) No other standards are normatively referenced These alloys have a good plastic elongation as well. Dr. Tamisha Denis received her Doctorate in Dental Medicine from the University of Pennsylvania School of Dental Medicine. Tarnish . Tarnish and corrosion of noble metal alloys. Dental amalgam is a liquid mercury and metal alloy mixture used in dentistry to fill cavities caused by tooth decay. Corrosion is not only a surface discoloration but is a disintegration of a metal by reaction with its environment. Tarnish is one of the disadvantages of dental amalgam, which precedes corrosion, and in fact it means real destruction of restorative materials. Alloys which meet these specified prerequisites have mass contents of 36-39% silver, 28-32.5% gold, 17-19.5% palladium, 0-0.1% iridium, 9.5 to 10.5% copper, 0.5-3.0 indium and 0.5-2.5% zinc, whereby the sum of indium and zinc does not exceed a maximum of 4%. Galvanic Corrosion and Tarnish in vivo. Discoloration comes through iron and mercury containing drugs, food debris, pigment producing bacteria. … Safety Dental alloys are … In achieving the above and other objects, a feature of the invention resides in tarnish-resistant precious-metal alloys consisting essentially of 36 to 39% by weight silver, 28 to 32.5% by weight gold, 17 to 19.5% by weight palladium, 0 to 0.1% by weight iridium, 9.5 to 10.5% by weight copper, 0.5 to 3% by weight indium and 0.5 to 2.5% by weight zinc, whereby the sum of indium and zinc does not exceed a maximum of 4% by weight. 5 Tarnish 6 Corrosion . Causes of Tarnish and Corrosion