Oral lichenoid reactions associated with amalgam: improvement after amalgam removal

Summary Background The pathogenetic relationship between oral lichenoid reactions (OLR) and dental amalgam fillings is still a matter of controversy. Objectives To determine the diagnostic value of patch tests with amalgam and inorganic mercury (INM) and the effect of amalgam removal in OLR associated with amalgam fillings. Methods In 134 consecutive patients 467 OLR were classified according to clinical criteria. One hundred and fifty‐nine biopsies from OLR lesions were histologically diagnosed according to the World Health Organization criteria for oral lichen planus (OLP) and compared with 47 OLP lesions from edentulous patients without amalgam exposure. One hundred and nineteen patients were patch tested with an amalgam series. In 105 patients (357 of 467 lesions) the amalgam fillings were removed regardless of the patch test results and OLR were re‐examined within a follow‐up period of about 3 years. Twenty‐nine patients refused amalgam removal and were taken as a control group. Results Eleven patients with OLR (8·2%) had skin lesions of lichen planus (LP). Histologically, the lesions in the OLR group could not be distinguished from those seen in the OLP group. Thirty‐three patients (27·7%) showed a positive patch test to INM or amalgam. Amalgam removal led to benefit in 102 of 105 patients (97·1%), of whom 31 (29·5%) were cured completely. Of 357 lesions, 213 (59·7%) cleared after removal of amalgam, whereas 65 (18·2%) did not improve. In the control group without amalgam removal (n = 29) only two patients (6·9%) showed an improvement (P