ABSTRACT
The oral region of the face is unique, with three different epithelial zones: the cutaneous lips, the vermillion, and the mucosa of the oral cavity. Areas in this region are considered non-keratinizing, meaning they lack the typical stratum corneum barrier; they include the labial mucosa and wet surface of the vermillion, ventral tongue, floor of the mouth, soft palate, and buccal mucosa. Susceptibility to allergens and irritants varies among these regions. The signs and symptoms of contact dermatitis in the oral cavity are less well defined than those seen with other regions covered in the series. While oral lichen planus is the prototypical example of classic pattern, extrinsic agents such as drugs and contactants should not be overlooked as a potential etiology. Oral hygiene products may cause allergic contact dermatitis in either the mucosa of the oral cavity or on the lips. The oral mucosa is frequently exposed to food. Food additives and flavorings may cause mucosal inflammation.
