Flare-Up Reaction During Treatment of Dental Metal Allergy

Objectives: Dental metal allergy (DMA) symptoms in extraoral regions are considered to represent systemic contact dermatitis (SCD) because allergenic dental metal ions released into the oral cavity reach the skin surface through the systemic circulation. Currently, the patch test (PT) and lymphocyte-stimulating test (LST) are commonly used for diagnosis of DMA; however, the validity of these tests is controversial. When dental materials suspected to cause the DMA are removed, patients are exposed to metal shavings, which can be considered an oral challenge test (OCT) to determine whether the metal is allergenic. The purpose of this study was to evaluate the validity of removing dental metals as an OCT for prognosis in DMA patients.
Methods: A retrospective study was performed utilizing clinical records of 1,731 patients diagnosed by dermatologists as having skin disease of unknown origin but suspicious for DMA. Dental metals were removed from 1,247 patients after PT and/or LST showed positivity for dental metals. The distributions of remission and non-remission of allergic symptoms including flare-up reaction after the OCT (removal of dental metals) were analyzed by Fisher’s exact test (α = 0.05). The correlation of PT and LST results was also analyzed.
Results: Allergic symptoms remitted within 1 year after removal of dental metals in 90% of patients. The ratio of remission of allergic symptom after removal of dental metals was significantly higher in patients who showed a flare-up reaction (odds ratio 12.47; P < 0.01). Over 70% of subjects were positive for mercury, nickel, or titanium on PT and LST; however, the PT and LST results were not significantly associated with symptom remission after dental metal removal.
Conclusions: Flare-up of allergic symptoms after removal of dental metals is a reliable indicator for good prognosis against DMA.