In vitro and in vivo biological responses to some dental alloys tested separately and in combinations.

Biocompatibility of dental alloys has been tested both in vivo and in vitro. In addition, combinations of dissimilar alloys were investigated in relation to possible enhanced corrosion by galvanic effects. Implantation tests, cytotoxicity tests on epithelial cells, macrophages and erythrocytes were performed, and the results compared. The severity of tissue response in implantation tests corresponded to the nobleness of the casting alloys joined to amalgam. Similar results were obtained in the in vitro macrophage test. All the alloys except the high-gold alloy (LM-Hard) had a toxic effect on epithelial cells. The combination of the casting alloys with amalgam diminished the toxic effect. Three of the alloys (amalgam, LM-Hard and Midi low-gold alloy) caused a slight haemolysis. Poor correlation was obtained between the agarose overlay tests, the haemolysis tests and the implantation tests.