Sensitization to palladium and nickel in Europe and the relationship with oral disease and dental alloys

Background
The role of palladium and nickel sensitization in oral disease and dermatitis is not fully understood.

Objectives
To investigate whether sensitization to these metals was associated with exposure to dental alloys and oral and skin complaints/symptoms in a European multicentre study.

Methods
In six dermatology clinics, patch tests with palladium (3% Na2PdCl4; Pd = 102.0 µmol/g) and nickel (5% NiSO4.6H2O; Ni = 190.2 µmol/g) were performed in consecutive patients, and patients' characteristics were collected with a questionnaire and a clinical investigation.

Results
In total, 906 patients were included, of whom 24.3% reacted to palladium and 25.2% to nickel. The rate of monosensitization was 6-7% for both metals. Palladium sensitization (as opposed to no sensitization to both metals) was associated with exposure to dental crowns [odds ratio (OR) 2.0], skin reactivity to metals (OR 2.8), oral lichenoid lesions (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.

Conclusions
Clinically, it is important for palladium-sensitized patients to undergo an oral examination, with particular attention to the presence of/exposure to dental crowns. In the case of metal contact allergy, exposure to dental crowns could play a role.