Epidemiological data indicatea lower prevalence of oral ulcers among smokers, with a protectiveeffect linked to increased mucosal keratinization and reduced susceptibilityto injury. Nicotine and its metabolitesmay further modulate the inflammatory response by downregulating proinflammatorycytokines (TNF-α, IL-1, IL-6) and upregulating IL-10. Similar trends have been observed with tobaccouse. This evidence concerns the gene TNF and Oral ulcer.