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Title toxicity of amalgams, alloys, and their elements and phases. Author Kaga M; Seale NS; Hanawa T; Ferracane JL; Waite DE; Okabe T Address Baylor College of Dentistry, Dallas, Texas. Source Dent Mater, 1991 Jan, 7:1, 68-72 Abstract The purpose of this study was to compare the relative cytotoxicity of amalgams, alloys, and their constituent elements and phases, by means of a rapid and sensitive in vitro cell culture test. Pure copper and zinc showed intensive cytotoxicity, significantly greater than that of pure silver and mercury. Pure tin was non-cytotoxic. The gamma-one phase (Ag2Hg3) revealed moderate cytotoxicity, which was significantly decreased by the addition of 1.5% and 5% Sn. However, the addition of 1.5% Zn to gamma 1 containing 1.5% Sn dramatically increased the cytotoxicity of gamma 1 to the same level as that of pure zinc. Whenever zinc was present in amalgams, higher cytotoxicity was revealed. High-copper amalgams showed the same cytotoxicity as a zinc-free low-copper amalgam. The addition of selenium did not reduce the cytotoxicity of amalgam. The cytotoxicity of amalgams was reduced after 24 h. The results of this study suggest that the major contributor to the cytotoxicity of alloy for amalgam is probably copper, while that for amalgam is zinc. Title Dental amalgam: the materials. Author Marshall SJ; Marshall GW Jr Address Department of Restorative Dentistry, University of California, San Francisco 94143. Source Adv Dent Res, 1992 Sep, 6:, 94-9 Abstract The goal of this presentation is to describe the material as it is used clinically, explain why small quantities of Hg can be released, and suggest ideas for amalgams that do not release mercury. A set amalgam is a dynamic material that undergoes many microstructural changes during clinical use, related to both the elevated temperature and corrosion-prone environment in the mouth and mechanical forces applied to the restoration. Amalgams can be divided roughly into two groups by their copper content: low Cu (traditional) and high Cu. High-Cu amalgams generally perform better clinically, but all amalgams corrode to some extent in the mouth. Some corrosion is deemed to be a positive factor, because corrosion product deposition reduces leakage at the margins of restorations; that is, the restorations are partly self-sealing. One of the reasons cited for the improved clinical performance of high-Cu amalgams over low-Cu amalgams is that the corrosion-prone phase, gamma 2, is nearly eliminated in high-Cu amalgams. Future research should involve improvements in the clinical performance of dental amalgams, studies of the mercury release from various types of amalgams and the toxic potential of this exposure, and the development of new amalgam systems that reduce the mercury exposure. Although the longevity of modern amalgams is impressive, it is important for their stability to be increased both clinically and microstructurally. An amalgam should be developed with a stable microstructure that, once set, would not change during clinical use. Microstructural changes lead to clinical deterioration. A stable system would not corrode, and the matrix transformation gamma 1 to beta 1 would be prohibited.(ABSTRACT TRUNCATED AT 250 WORDS) Title Interactions between dental amalgams and the oral environment. Author Marek M Address School of Materials Engineering, Georgia Institute of Technology, Atlanta 30332. Source Adv Dent Res, 1992 Sep, 6:, 100-9 Abstract Dental amalgam fillings interact in a complex way with the environment in the oral cavity as they are subjected to chemical, biological, mechanical, and thermal forces. These forces change the restoration's appearance and properties, while metal ions, amalgam debris, non-metallic corrosion products, and mercury vapor are released into the oral cavity. The phenomena and conditions that affect the amalgam/environment interaction include the chemistry and biochemistry of the environment, formation of biofilms on the amalgam surfaces, existence of localized corrosion cells, galvanic contacts with other metallic restorations, abrasion during mastication, and synergistic effects of the different forces. Corrosion processes result in a degradation of the functional amalgam properties, while tarnishing reactions cause discoloration. Corrosion degradation of amalgam fillings is due mainly to localized corrosion cells in pores and crevices. Corrosion on occlusal surfaces is accelerated by abrasion during mastication, which removes the protective surface films. The average total amounts of metal species, including mercury, released per day in vivo from a restoration have not been determined. Much of the reported indirect evidence for high mercury release rates is either unreliable or controversial. A more detailed investigation is needed and will require the development of more sophisticated techniques of sampling in vivo, as well as both experimental and theoretical modeling in vitro. Title The prevalence of sensitivity to constituents of dental alloys. Author Namikoshi T; Yoshimatsu T; Suga K; Fujii H; Yasuda K Address Department of Removable Prosthodontics, Nagasaki University School of Dentistry, Japan. Source J Oral Rehabil, 1990 Jul, 17:4, 377-81 Abstract Ninety-five participants were epicutaneous patch tested in order to determine the prevalence of sensitivity to components of dental alloys. Seventeen individuals (17.9%) developed allergic reactions, which were caused by mercury (10.5%), copper (2.1%), nickel, cobalt, tin, gold and zinc (1.1%). Eight of 17 allergic responders had a history of dermatitis from metal contact. The results show that there is a need for careful immunological considerations during the selection of suitable alloys, particularly in the case of patients with lesions suspected of being caused by dental alloys. Title Placental transfer of heavy metals in normal pregnant Japanese women. Author Tsuchiya H; Mitani K; Kodama K; Nakata T Address Source Arch Environ Health, 1984 Jan, 39:1, 11-7 Abstract To investigate the interrelation of heavy metals and the influence on next generation, total mercury and methylmercury, lead, cadmium, manganese, copper, zinc, and iron were determined in the maternal blood, placenta, umbilical cord, and umbilical cord blood. Samples were collected at delivery from 231 pregnant women who were living in the city of Nagoya, located in the central district of Japan, during 1974 and 1978. Total mercury and methylmercury, cadmium, and iron were higher in cord blood than in maternal blood, whereas copper and zinc were lower. Significant positive correlations were observed between maternal and cord blood with regard to total mercury and methylmercury, lead, cadmium, and manganese contents. Significant correlations were also observed between many pairs of metals, particularly in umbilical cord and its blood. Title Concentrations of heavy metals in maternal and umbilical cord blood. Author Ong CN; Chia SE; Foo SC; Ong HY; Tsakok M; Liouw P Address Department of Community Medicine, National University of Singapore. Source Biometals, 1993 Spr, 6:1, 61-6 Abstract Concentrations of lead, cadmium, methylmercury and total mercury were measured in maternal and umbilical cord blood using graphite atomic absorption spectrometry. Two essential metals, copper and zinc, were also determined using ion chromatography. Lead, copper and zinc were found to be lower in the cord blood whereas methylmercury and total mercury were higher in cord blood than in maternal blood. Little differences were noted for cadmium in maternal and cord blood. Significant positive correlations were observed between the concentrations in maternal and cord blood with regard to lead (correlation coefficient, r = 0.44), copper (r = 0.34), zinc (r = 0.29), methylmercury (r = 0.44) and total mercury (r = 0.58). These results suggest that, like essential metals, most heavy metals can move rather freely across the human placenta. The potential health effects of heavy metal transfer from mothers to young infants cannot be discounted. Title Reference intervals for trace elements in blood: significance of risk factors. Author Grandjean P; Nielsen GD; Jırgensen PJ; Hırder M Address Institute of Community Health, Odense University, Denmark. Source Scand J Clin Lab Invest, 1992 Jun, 52:4, 321-37 Abstract A random sample of 100 men and 100 women was examined for whole-blood concentrations of mercury, lead, cadmium and selenium, and the serum concentrations of selenium, nickel, fluoride, aluminium, zinc and copper. Major predictors were sex, hormonal factors (pregnancy, menopause, use of oral contraceptives), age, tobacco smoking and alcohol drinking. Among notable associations, increased blood-mercury was related to the presence of more than four amalgam fillings in the teeth. Blood-mercury correlated with blood-selenium, but a relation to fish intake could only be demonstrated for the former parameter. In women, blood-lead appeared to increase with age, with the highest levels seen after the menopause. Serum-nickel was slightly lower in patients with nickel-related contact eczema. Only the selenium concentrations showed a slight increase in individuals taking mineral supplements. Serum-zinc concentrations decreased considerably during the day. Thus, due to the substantial influence of physiological and environmental factors, individual results must be interpreted in the light of the known predictors for the trace element concentration. However, population-based reference intervals for trace elements in blood are useful to explore geographic and temporal variations.