title: Cytotoxicity of gallium and indium ions compared with mercuric ion.
abstract: The use of mercury in dental amalgam restorations has become the subject of political controversy despite its long history of safe clinical use, and alternative materials based on gallium and indium rather than mercury have been developed. The biological safety of these metals must be evaluated, as part of their assessment as mercury substitutes. The cytotoxicities of mercury (II) nitrate, gallium (III) nitrate, and indium (III) nitrate were assessed at concentrations between 0.001 mmol/L and 1.0 mmol/L, using L929 mouse fibroblasts and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) colorimetric assay and scanning electron microscopy. The mitochondrial dehydrogenase activity at each metal ion concentration as a percentage of the control was calculated from the absorbance values. The 50% inhibition concentration of mercury (II) nitrate was 0.35 mmol/L for cells in the rapid-growth phase and at confluence; gallium (III) nitrate and indium (III) nitrate did not significantly inhibit dehydrogenase activity in either the growing or confluent phase. Gallium and indium ions were not significantly toxic under the conditions of this assay.
authors.affiliation: University of Melbourne, School of Dental Science, Victoria, Australia.
authors.forename: J E
authors.initials: JE
authors.lastname: Chandler
authors.forename: H H
authors.initials: HH
authors.lastname: Messer
authors.forename: G
authors.initials: G
authors.lastname: Ellender
mesh_terms: D000818:Animals; D002452:Cell Count / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D003124:Colorimetry; D004396:Coloring Agents; D005347:Fibroblasts / Q000187:drug effects* / Q000201:enzymology / Q000648:ultrastructure; D005708:Gallium / Q000633:toxicity*; D007204:Indium / Q000633:toxicity*; D008628:Mercury / Q000633:toxicity*; D017669:Mercury Compounds / Q000633:toxicity; D051379:Mice; D008855:Microscopy, Electron, Scanning; D008928:Mitochondria / Q000187:drug effects / Q000201:enzymology; D009566:Nitrates / Q000633:toxicity; D010088:Oxidoreductases / Q000187:drug effects / Q000378:metabolism; D013056:Spectrophotometry, Ultraviolet; D013778:Tetrazolium Salts; D013844:Thiazoles
chemical_list: D004396:Coloring Agents; D017669:Mercury Compounds; D009566:Nitrates; D013778:Tetrazolium Salts; D013844:Thiazoles; D007204:Indium; C029948:mercury nitrate; D005708:Gallium; D010088:Oxidoreductases; C022616:thiazolyl blue; D008628:Mercury; C027235:gallium nitrate; C089767:indium nitrate