 This study will evaluate the effectiveness of dexamethasone 0.01 solution in treating pain associated with oral lichen planus, a chronic disease that causes painful ulcers inside the mouth. The cause of lichen planus not known, but it may be related to an allergic or immune reaction. This study will examine what causes the disease, the pain associated with it, its impact on patients lives and the use of dexamethasone to treat it. 