In animal experiments, SLS (sodium lauryl sulphate), a common ingredient in tooth paste, was found to damage the oral mucosa. A single exposure to SLS in a concentration comparable to that found in tooth paste (2%) and higher (4% and 8%) resulted in a dose-related irritant inflammatory reaction of the exposed mucosa. SLS applied to the buccal mucosa of mice resulted in initial surface necrosis and neutrophil infiltrations followed by mononuclear cell infiltrations dominated by CD4+ T cells. Increased concentrations of SLS gave more severe damage. The highest number of CD4+ T cells was observed from 6 hours to 24 hours after SLS application, and 24 hours after the SLS exposure the necrotic epithelium was repaired.
Mucosa was also exposed to a hapten (1% oxazolone) in order to compare the SLS reaction to allergy-induced damage. No mucosal changes were observed after oxazolone exposure, however oxazolone caused increased levels of the cytokine IL-2 both at the local application site and in the regional and distant lymph nodes. These observations further emphasize that IL-2 is a necessary cytokine to create memory T cells that are induced by haptens and that the SLS reaction is different from allergy.
This model is a valuable tool for further studies of CS and irritant reactions in oral mucosal membranes. It could be used for testing dental materials, dentifrices and mouth washes.