Sensitization to Palladium and Nickel and the Relation to Oral Disease and Dental Alloys in Europe

Objectives: The aims were to assess whether sensitization to palladium and/or nickel is associated with exposure to different subsets of dental alloys and oral symptoms/complaints in 6 Western European dermatology clinics. Furthermore, possible associations between exposure to dental alloys and oral symptoms/complaints were investigated.
Methods: In 6 dermatology clinics patch tests with palladium (3% Na₂PdCl₄; Pd = 102.0 µMol.g^-1) and nickel (5% NiSO₄*6H₂O; Ni = 190.2 µMol.g^-1) were performed in consecutive patients. Paients’ characteristics were collected using a questionnaire and a clinical examination. Subsets of dental alloys contained amalgam, metal based crowns, prostheses, and orthodontic retention wires. The investigated clinical variables were eczema, history of metal allergic contact dermatitis (ACD), oral lichenoid lesions (OLL), stomatitis, xerostomia, metal taste and burning/pain. Pearson chi-square tests, adjusted residuals, odds ratios, and Z-tests [p<0.05; 95% confidence intervals (95%CI)] were used for statistical analyses.
Results: In total 906 patients from 6 clinics [Amsterdam(n=66), Barcelona(n=117), Bari(n=90), Basel(n=175), Coimbra(n=189), and Leuven(n=252)] were included. 24.3% reacted to palladium and 25.2% to nickel. Monosensitization was 6-7% for both metals. Palladium sensitization (as opposed to no sensitization to both metals) was associated with exposure to dental crowns (OR=2.0), skin reactivity to metals (OR=2.8), OLL (OR=4.7), xerostomia (OR=7.3) and metal taste (OR=20.7), but not with eczema, stomatitis, or oral burning sensation. Additionally, xerostomia (OR=8.7) and metal taste (OR=4.6) were associated with sensitization to both metals. Associations between exposure to various dental alloys and clinical variables are presented in Table 1.
Conclusions: The prevalence of palladium and nickel sensitization is comparable and was significantly elevated in patients with dental crowns. Exposure to dental crowns was strongly associated with a history of metal ACD, OLL, xerostomia, and metal taste. The trias: dental crowns, sensitization, and oral, and lesions/complaints (oral and dermatologic) is of concern for the daily dermatologic and dental practice.