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Allergy to palladium in dental alloys

A 19-year-old female patient was observed with the following symptoms: relapsing painful swelling of the right cheek, pain in the mouth at the site where a metal bridge had been applied, generalized itching and dizziness. These symptoms started six months after replacing some molar teeth with the metal bridge. The bridge contained gold, silver, platinum, palladium, copper, zinc, magnesium, bismuth and tin. Patch testing with the ICDRG standard series gave positive reactions to nickel and cobalt, while the reaction to potassium dichromate was doubtful. Tests with salts of the metals present in the bridge showed only a strong positive reaction to palladium dichloride (2% aq.). All other materials including platinum chloride 2% were negative. Palladium was present in the metal bridge at 5%; this bridge was replaced by another one without any metal. All symptoms disappeared within a couple of days. The patient has since remained well. Palladium is a metal belonging to the platinum group. Because of its cheapness it is used in jewellery especially as an addition to or a replacement of platinum. Allergy to palladium has been reported by Munro-A:,hman et al. (1969), where a research chemist was found to have a positive reaction to nickel-free sodium palladium dichloride (1 % and 0.1 %). In the present case no trace of nickel in the test palladium dichloride could be found with the dimethylglyoxime spot test. Sheard (1955) described a patient with sensitization to a platinum ring, combined with a reaction on patch testing with a palladium ring. Our patient has worn a platinum ring for a year without trouble. Local and systemic reactions from absorption of metals used in the oral cavity seem to be rare. Feuermann (1975) described a patient with recurrent dermatitis, a positive patch test to ammoniated mercury and disappearance of the attacks after the removed of mercury amalgam fillings. Glendenning (1971) published a case of allergy to cobalt in a metal denture as a cause of hand dermatitis. Systemic reactions from dental alloys containing chromates or nickel may occur in the same way as from cobalt. In our patient sensitization to palladium from a metal bridge in the oral cavity can probably be considered as the cause of the local and systemic symptoms.