Abstract
The oral cavity is constantly exposed to many pathogens potentially causing allergic reaction. The major aetiological factors of oral allergic reactions are dental materials, food, food additive, drugs and oral hygiene products. The oral allergic reaction has wide spectrum of clinical presentations, such as angioedema, allergic contact stomatitis/cheilitis, oral lichenoid reactions and plasma cell gingivitis (PCG). PCG is an uncommon inflammatory condition of the gingiva characterised histopathologically by plasma cell infiltration in the gingivae. Hypersensitivity reaction due to certain antigens is thought to be the primary aetiological factor. The diagnosis of PCG is made on the basis of histopathological examination. Management involves both medical and surgical approaches. However, no treatment clearly stands out as consistently effective.