White lesions due to subepithelial change have normal overlying epithelium, but changes in the connective tissue partially mask blood vessels and cause the area to appear white, yellow or tan. These lesions have a smooth translucent surface, do not rub off, and are not painful.
Scarring (subepithelial fibrosis) of the oral mucosa can appear as white surface lesions with a smooth surface. They are non-painful and do not rub off. Diagnosis is made by history of trauma or surgery to the area. No treatment is necessary.