It was the purpose of the study to test the efficacy of dissolvent tablets containing mutanase and protease in preventing formation of plaque on the fitting surface of complete dentures. The study group consisted of 60 denture wearers with denture stomatitis who were assigned randomly into an enzyme group, a placebo group, or a Steradent group. After denture treatment was completed the patients were instructed to immerse the new dentures for 15 min once daily for one month in the denture cleanser. The amount of denture plaque, the clinical condition of the palatal mucosa, and the concentration of yeasts in mucosal and denture smears were recorded while the patients used their original dentures and after the experimental period. The study was designed and carried out as a double-blind study. New denture plaque had formed in all patients; however in the enzyme group significantly reduced plaque scores were recorded as compared with the plaque scores recorded on the original dentures. The Steradent tablets or the placebo tablets had no apparent effect.