any structural anomaly of the stratified squamous epithelium that forms part of the oral mucosa and lines the inner aspect of the oral cavity; depending on the mouth region, the epithelium may be non-keratinized or keratinized; non-keratinized squamous epithelium covers the soft palate, inner lips, inner cheeks, and the floor of the mouth, and ventral surface of the tongue; keratinized squamous epithelium is present in the attached gingiva and hard palate as well as areas of the dorsal surface of the tongue