Amalgam-contact hypersensitivity lesions and oral lichen planus

Objective. The purpose of this study was to investigate the relationship between amalgam restorations and oral lichen planus. Study design. Eighty-one patients with oral lichenoid lesions were characterized clinically and skin patch tested for amalgam or mercury hypersensitivity. Thirty-three of these patients had amalgam fillings in contact with oral lesions replaced and were followed to determine the outcome. Results. Clinically, 2 patient groups were identified: (1) 30 patients with probable amalgam-contact hypersensitivity lesions (ACHLs) and (2) 51 patients with oral lichen planus (OLP) but no clear relationship with amalgam. Seventy percent of ACHL cases were patch test positive for amalgam or mercury compared with only 3.9% of OLP cases (P <.0001). Amalgam replacement resulted in lesion improvement in 93% of ACHL cases. No such improvement was observed in the OLP cases treated (P <.001). Conclusion. OLP is a heterogeneous condition within which an ACHL subgroup can be identified. ACHLs, but not other OLP lesions, respond favorably to amalgam replacement. A strong clinical association between lesions and amalgam restorations plus a positive patch test result was a good predictor of lesion improvement on amalgam replacement.