Certain
dental alloys have been claimed to cause gingival and periodontal
inflammation. However, little information is available on the molecules mediating the mechanism of such an effect. Recently, a three-dimensional cell culture system consisting of human fibroblasts and keratinocytes has been introduced for evaluating the irritancy of cosmetic products, including the analysis of inflammatory mediators. In the present study the influence of pure metals and a high noble dental cast
alloy upon cell viability and the synthesis of the proinflammatory mediator
interleukin-6 was recorded in this in vitro skin equivalent model. The cultures were exposed to test specimens fabricated from
copper,
nickel,
cobalt,
zinc,
palladium,
tin,
indium, a high noble cast
alloy and a dental ceramic. Cell vitality was reduced after a 24 h exposure to
copper (14-25% of untreated controls),
cobalt (60%),
zinc (63%),
indium (85%),
nickel (87%), and the heat treated and not heat treated high noble cast
alloy (87%/90%). Dental ceramic,
palladium and
tin did not influence cell viability. Increased
IL-6 levels were observed in cultures exposed to
copper (5-19-fold compared to untreated controls),
zinc (16-fold),
cobalt (12-fold),
nickel (10-fold) and
palladium (4-fold). Other materials tested produced
IL-6 levels comparable to those of untreated controls. Our findings suggest that
metal ions are involved in proinflammatory activity at low toxicity and non-toxic levels as assessed by different
biological endpoints.