The purpose of this study was to assess the anticalculus efficacy and long-term safety of a new stannous fluoride dentifrice containing sodium hexametaphosphate. This trial was a randomized, double-blind, parallel-group, 6-month study where, after a prophylaxis, subjects brushed twice daily with either a stabilized 0.454% stannous fluoride/13% sodium hexametaphosphate dentifrice (Crest Pro-Health) or a marketed multibenefit triclosan/copolymer control dentifrice. Study subjects were known to form supragingival calculus and had previously demonstrated the ability to form at least 1.5 mm using the Volpe-Manhold Calculus Index over a 2-month pretest period. Comparisons between treatments for anticalculus efficacy were performed using analysis of covariance. Eighty subjects were randomized into one of two treatment groups after stratification on gender and baseline calculus scores and then monitored for calculus formation, soft tissue tolerance, and extrinsic stain. The mean calculus score for the stannous fluoride/sodium hexametaphosphate group was statistically significantly lower than that of the triclosan/copolymer group at both months 3 and 6 (P < .01). At month 3, the stannous fluoride/sodium hexametaphosphate group had an adjusted mean 54% lower than that of the triclosan/copolymer group. At month 6, the stannous fluoride/sodium hexametaphosphate group had an adjusted mean 56% lower than that of the triclosan/copolymer group. Both dentifrices were well tolerated and neither dentifrice group developed appreciable extrinsic stain over the 6-month trial period. Overall, the stannous fluoride/sodium hexametaphosphate dentifrice had superior anticalculus efficacy relative to the marketed triclosan/copolymer control and a comparable soft tissue safety and extrinsic stain profile.