Two cases with nickel-induced oral mucosal hyperplasia: a rare clinical form of allergic contact stomatitis?

Allergic contact stomatitis (ACS) can occur with variable clinical presentations such as erythematous, erosive, and lichenoid forms. Burning mouth symptoms may also be a result of allergic contact stomatitis. Additionally, gingival hyperplasia has been reported in exceptional cases of ACS caused by dental metals. Here, two rare cases are presented of nickel-induced oral mucosal hyperplasia with gingival and upper palatal involvement from metal-porcelain crowns and metal-acrylic upper denture, respectively. In both cases the diagnosis was made on the basis of the positive patch test results to nickel sulfate and the regression of the lesions after removing the nickel containing dental materials. Nickel-induced ACS should be borne in mind in every case of oral mucosal hyperplasia appearing after dental procedures, especially in the presence of previous allergies and sensitization risks such as ear piercing. It might be further suggested to include this variant within the clinical forms of ACS.