Literature concerning the relationship between denture plaque, oral pathology, and the nature and effectiveness of the products commercially available for cleaning dentures has been reviewed. The literature reports indicate that (1) plaque on the tissue surface side of the denture is unquestionably a major etiologic factor in the pathogenesis of denture stomatitis, inflammatory papillary hyperplasia, and chronic candidiasis and (2) there are shortcomings in the popular products used by the public to clean their dentures. The protocol and results of a study to test the plaque removal effectiveness of a new denture cleansing product are described. In this study, the plaque removal effectiveness of the ultrasonic device tested, when used with water alone, was found to be substantially greater than that of two popular alkaline-peroxide soak-type denture cleansers, Efferdent and Polident.