Relationship between Oral Lichen Planus and Dental Metal Allergy

Objective: Some mucocutaneous diseases caused by dental metal allergy have been reported, for example palmoplantar pustulosis, contact dermatitis, atopic dermatitis, oral lichen planus (OLP) etc. At Dental Allergy Clinic of Tokyo Medical and Dental University, we made a medical examination and inspection about dental allergy since 1998. The purpose of this study was to investigate the tendency of dental metal allergy in our clinic from 2006 to 2007, and compared with that from 1998 to 2005. Furthermore, causes of OLP have been still uncertain. One more purpose of this study was to evaluate relationship between OLP and dental metal allergy by investigating outpatients among our clinic. Methods: We investigated the distribution of age and sex of the outpatients who consulted our clinic from January 2006 to December 2007. Patch testing was done using our standard dental metal reagent according to the protocol recommended by the International Contact Dermatitis Research Group. In some cases, additionally lymphocyte stimulation test (LST) was performed for nickel (Ni), cobalt (Co), gold (Au) and palladium (Pd). Results: 485 patients had been patch testing at our clinic during 2006 to 2007. The positive rate to each metal were as follows; Ni 21.4%, Co 10.7%, Hg 9.7%, Pd 9.5%. Ni was steadily the most frequency positive elements of patch test from 1998 to 2007. On the other hand, the number of mercury positive patient was reduced. The percentage of patients with symptoms in the oral area was about 30% among outpatients. The rate of patients diagnosed as OLP was about 5%. Over 50% of the patients showed a certain allergic positive reaction among OLP patients. Conclusion: We suppose that the patch test positive rate is changing among trend of dental treatment. These results suggested that OLP had been caused by dental metal allergy at certain rate.