In-vitro permeability of porcine oral mucosa after epithelial separation, stripping and hydration.

The permeability of porcine skin, gingiva, floor of mouth and buccal mucosa was measured in perfusion chambers using isotopically-labelled water and horseradish peroxidase. Values obtained for the permeability of the epithelium of each of these regions, after separation from the connective tissue with EDTA, did not differ significantly from those obtained for the intact tissue; however, the connective tissue alone had a permeability 2-8 times greater than that of the whole tissue. Stripping the surface layers of the floor of mouth mucosa increased its permeability to that of connective tissue. These results indicate that the functional permeability barrier of the oral mucosa, like that of skin, is located in the epithelium and occupies the superficial layers. After exposure to an aqueous environment for up to 67 h, the permeability of skin and keratinized oral mucosa showed similar but slight increases whereas that of non-keratinized mucosa showed a more rapid rise. These differences may reflect the different composition of the intercellular permeability barrier in keratinized and non-keratinized oral tissues.