Evaluation of the biocompatibility of various dental alloys: Part 2--Allergenical potentials. 
The metal alloys which were investigated histopathologically in the first part of this study, were examined with respect to their allergic potentials using the patch test.  Results from 60 subjects (aged 17-23) were evaluated following exposure to nickel sulphate, potassium dichromate, silver nitrate, cobalt nitrate, copper sulphate, palladium chloride, platinum chloride and gold chloride.  Nickel sulphate produced the most vigorous allergic response whereas gold chloride showed the least of all.  The remaining solutions were ranked in decreasing order of severity as follows: potassium dichromate, cobalt nitrate, silver nitrate, copper sulphate, palladium chloride and platinum chloride.  Patch testing is indicated in any patient with a history of allergy or sensitivity to a metal.  The use of nickel containing alloys in such patients should also be avoided.