Furthermore, there is sufficient evidence of the carcinogenicity of smokeless tobacco. Smokeless tobacco causes cancers of the oral cavity and potentially malignant disorders (precancers) arise at the site where smokeless tobacco is regularly placed. Smoking cessation, on the other hand, is associated with the potential for reversal of precancer, enhanced outcomes following periodontal treatment, and better periodontal status compared to patients who continue to smoke. The risk for oral cancer and periodontal disease progression of former smokers approximates that of never smokers after some 10 years of quitting smoking.