The purpose of this two-year clinical study was to provide a comparison of the anticaries efficacy associated with two commercially available, American Dental Association-accepted dentifrices: Colgate Total Toothpaste, which contains 0.3% triclosan and 2% copolymer in a 0.243% sodium fluoride/silica base; and Crest Cavity Fighting Toothpaste with Fluoristat, which contains 0.243% sodium fluoride in a silica base. The study was conducted in harmony with the published 1988 American Dental Association guidelines for studies geared toward the comparison of fluoride dentifrices. The study employed a double-blind parallel-group design, and involved adults living in communities throughout Israel. Qualifying subjects were randomly assigned to the two treatment groups, with multiple subjects in the same household all assigned to the dentifrice randomly allocated to the first among them. Caries examinations were conducted in accordance with U.S. Food and Drug Administration guidelines for the clinical evaluation of drugs to prevent dental caries. Two calibrated examiners performed all of the measurements. After treatment assignment, study participants were instructed to brush their teeth at home with their assigned dentifrice at least twice daily. Brushing instructions were reinforced by indoctrination in proper oral hygiene techniques by dental professionals, supplemented by pamphlets supplied by the sponsor and yearly mailings to participants, emphasizing good oral hygiene and the need to ensure compliance with the study. Post-baseline examinations were performed after one year of product use, and again after two years of product use. Three-thousand, three-hundred and ninety-two (3,392) subjects completed this two-year study. For these subjects, the mean caries scores (DFS, decayed or filled surfaces) at baseline were 21.96 for the Colgate Total Toothpaste group, and 21.49 for the Crest Cavity Fighting Toothpaste with Fluoristat group. For caries increment after one year, the respective means were 1.37 for the Colgate Total Toothpaste group, and 1.56 for the Crest Cavity Fighting Toothpaste with Fluoristat group. After two years, the mean caries increments were 1.46 for the Colgate Total Toothpaste group, and 1.75 for the Crest Cavity Fighting Toothpaste with Fluoristat group. No statically significant difference was indicated between the treatment groups at baseline. However, for both the one-year and two-year increments, there was a statistically significant difference between treatment groups. Relative to the Crest Cavity Fighting Toothpaste with Fluoristat group, the Colgate Total Toothpaste group presented a 12.2% reduction in caries increment scores at one year, and a 16.6% reduction in caries increment scores at two years. In accordance with the procedures and standards provided by the published guidelines of the American Dental Association for the comparison of the anticaries efficacy of fluoride dentifrices, the results of this study support the conclusion that Colgate Total Toothpaste provides a superior level of coronal anticaries efficacy compared to Crest Cavity Fighting Toothpaste with Fluoristat.