Contact allergy to gold in dental patients.

Gold sodium thiosulphate (GSTS) in patch test series commonly yields positive reactions. In this study of dental patients, the clinical relevance of these positive reactions, the suitability of gold compounds as patch test materials, and value of the lymphocyte proliferation test in gold contact allergy, were evaluated. The frequency of positive patch test reactions to GSTS was 12.4% in the dental series. Fifty-two patients, only two of whom were male, were studied. Thirteen (25%) had had symptoms from jewellery or dental restorations. However, in most cases gold allergy was subclinical. A 10% aqueous solution of gold sodium thiomalate (GSTM) was almost as good as 0.5% GSTS in petrolatum as a marker of gold contact allergy, but 0.001% potassium dicyanoaurate (PDCA) yielded a high percentage of false-negative results. Seventy-three per cent of the subjects with positive patch tests to GSTS responded to gold compounds in vitro in the lymphocyte proliferation test, whereas 13 controls without gold contact sensitivity were negative. Consistent results in skin and lymphocyte proliferation tests provide support for the concept that gold salt-induced 'allergic-like' reactions are truly allergic in nature.