A two phase, six month, double blind clinical study was conducted to compare the effect on supragingival calculus deposits of a dentifrice containing 1.30% soluble pyrophosphate (from 2.0% tetrasodium pyrophosphate) with and without the presence of 1.50% of a copolymer of methoxyethylene and maleic acid. In Phase I of the study, male and female adult subjects were stratified into two balanced groups according to baseline calculus scores. They received an oral prophylaxis and were assigned to the use of either a dentifrice containing 1.30% soluble pyrophosphate and 1.50% copolymer or to a placebo dentifrice that did not contain the anticalculus ingredients. After three months use of the products, the subjects received a calculus examination. The subjects were then entered into Phase II of the study where they were restratified into two balanced groups. They again received an oral prophylaxis and were assigned to the use of either a dentifrice containing 1.30% soluble pyrophosphate with no copolymer or to a placebo dentifrice. The results from the three month calculus examination indicated that the dentifrice containing soluble pyrophosphate and a copolymer reduced supragingival calculus deposits by 29.54%, as compared to the placebo dentifrice (less than 99% level of confidence). The results from the six month calculus examinations indicated that the dentifrice containing soluble pyrophosphate without the copolymer did not provide a statistically significant reduction in supragingival calculus after an oral prophylaxis. Thus, it is concluded that the presence of the copolymer in the soluble pyrophosphate dentifrice was essential for obtaining a statistically significant anticalculus effect.