Background: Contact allergy to dental materials is poorly understood; clinical manifestations are heterogeneous.
Objective: To analyse positive patch test reactions to metals (as their alloys or salts) used in dentistry together with clinical symptoms and possible relevance to dental fillings.
Methods: We retrospectively analysed 206 patients who underwent patch testing with metals used in dentistry because of suspected contact allergy to them.
Results: Twenty-eight of 206 patients had positive patch test reactions to metals used in dentistry. The number of positive patch test reactions was highest for gold sodium thiosulfate, palladium chloride, and nickel sulfate (n = 10, respectively), followed by amalgam, ammoniated mercury, and cobalt chloride (n = 4, respectively) and amalgam-mixed metals (including copper, tin, zinc, and silicon), and ammonium tetrachloroplatinate (n = 1). Only 14 (7%) of 206 patients had a clinically relevant contact allergy with conditions of the oral mucosa (n = 7 with lichen planus and n = 7 with stomatitis) and positive patch test reactions to dental metals containing the suspected allergen. Improvement of symptoms was assessed in one patient with amalgam contact allergy 2 weeks after removal of dental fillings.
Conclusions: Clinically relevant contact allergies to dental metals are infrequent. Gold sodium thiosulfate and palladium chloride presented the most frequent contact allergens.