SF-ICP-MS Analysis of Palladium in Fluids of Patients Sensitized to Metal-Based Dental Restorations

Palladium (Pd) belongs to the platinum group elements and its use has more than doubled in the past ten years. Encouraged by positive patch test results in some patients suffering from oral syndromes, Pd was included in the routine patch testing for contact dermatitis. In the present study, differences in the trend of sensitization to Pd in a contact derma- titis clinic population between 1996 and 2006 were evaluated. Since many in vitro studies have confirmed the corrosion of dental alloys and indicated that metal components are released in the oral cavity, Pd content was examined in leaching so- lutions from dental prostheses and in samples of saliva, serum and urine of subjects with adverse reaction to dental pros- theses. Measurements were performed by means of Sector Field Inductively Coupled Plasma-Mass Spectrometry (SF- ICP-MS). Results showed that the frequency of mono-reactions to Pd are increased from 1996 (0.11%) to 2006 (1.6%), suggesting that this metal is becoming a "new" potential allergen. The mean values of Pd levels detected in urine were higher than those found in saliva and in serum. All biological samples collected from patients showed significantly higher levels of Pd than controls (saliva, 255 ng/L vs 11; serum, 60 vs 15; urine, 580 vs 20). Moreover, after removal of the pros- theses a consistent reduction of Pd content in fluids was observed.