Biocompatibility of alloys used in orthodontics evaluated by cell culture tests

The cytotoxicity of the most common alloys used in orthodontic appliances w as determined by cell culture testing. Human gingival fibroblasts were cult ured on 304 and 316 stainless steel, on brazing alloy composed of palladium (Pd), copper (Cu), and silver (Ag), and on plastic substrate (control). St udies were carried out with SEM and radiolabeled precursor incorporation. C ells were cultured in MEM without serum but with the addition of H-3-thymid ine to evaluate cell proliferation and H-3-glucosamine to evaluate glycosam inoglycan (GAG) synthesis and secretion in the culture medium. Moreover, gi ngival fibroblasts were cultured in the presence of some metal ions general ly released by orthodontic appliances to evaluate the cytotoxic effects of single ions. Morphologic observations with SEM and radiolabeled incorporati on studies showed that 304 and 316 stainless steel were more biocompatible than the brazing alloy. Among the metal ions tested, Ag and Pd, constituent s of the brazing alloy, showed the highest cytotoxicity. (C) 2000 John Wile y & Sons, Inc.