Chemically induced inflammation in rat oral mucosa

The toxic, irritative, and sensitizing effects of topically applied sodium lauryl sulfate (SLS), dithranol triacetate (DTA), nonanoic acid in methyl- or propyl ester (NAM, NAP) in the buccal mucosa were investigated in a Sprague-Dawley rat model. Semi-quantitative evaluations of cellular infiltrates were performed in routine histologic preparations. The toxic potential was tested with 2% and 0.2% solutions. All substances, except 0.2% SLS, caused an increased cellularity, mainly of a mononuclear cell type. The low dose of NAM induced stronger inflammatory reactions than the high dose. Repeated applications of 2% solutions decreased the response compared to one application, except for NAM, where a clear irritative potential was observed. Pre-exposure of dorsal skin prior to buccal painting resulted in an enhanced reaction to NAM and NAP, whereas no sensitizing capacity was noted in SLS or DTA in this model.