Intraoral metal contact allergy as a possible risk factor for oral squamous cell carcinoma.

OBJECTIVES: Intraoral exposure to dental restorations can cause contact allergy that may induce carcinogenesis. We investigated the relationship of intraoral metal contact allergy to epithelial carcinogenesis. METHODS: The prevalence of positive patch test reactions to dental restoration metals in 65 prospectively enrolled patients with newly or previously diagnosed oral squamous cell carcinoma (SCC) was compared to that in 48 control patients. The relative risk of oral SCC was estimated by calculating odds ratios for exposure to dental metals resulting in allergy. RESULTS: Of the 65 patients with oral SCC, 34% were allergic to at least 1 adjacent metal. They were 1.57 times as likely as control patients to have metal contact allergy (odds ratio, 1.57; 95% confidence interval, 0.65 to 3.80) and more than 3 times as likely to react to mercury (odds ratio, 3.20; 95% confidence interval, 0.42 to 33.20). CONCLUSIONS: Patients with oral SCC who have metal dental restorations should undergo patch testing and possible removal of the restorations if their reactions are positive.