TNF and oral lichen planus: The etiology of OLP, which has periods of improvement and relapses, is currently unknown, but involves, among other factors, activated cytotoxic CD8+ T cells, metalloproteinase activation, an influx of mast cells and macrophages accompanied by activation of NF-κß and increased levels of the cytokines interleukin-4 (IL-4), IL-6, IL-8, interferon-γ, and tumor necrosis factor-α (TNF-α) [1,2,3].