Recently, leukoplakia of the maxillary vestibule was described in patients with no traditional risk factors but who had used Viadent products. We designed a case-control study to evaluate the hypothesis that Viadent users were more likely to have lesions. One hundred and forty-eight cases and controls were identified through the Section of Oral and Maxillofacial Pathology. Cases and controls were administered a questionnaire about Viadent use and other known risks. Results of crude, stratified, and logistic regression analyses showed that use of Viadent products was a risk indicator for leukoplakia (adjusted OR = 9.7, 95% CI = 4.7-21.6), with a strong dose-response relation.