Laboratory studies involving crystal growth inhibition and plaque biofilm calcification were conducted to confirm the anticalculus potential of a dual-action whitening dentifrice containing sodium hexametaphosphate, a novel, enamel-safe, antitartar agent. Calcium hydroxyapatite crystal growth was significantly inhibited following direct supernate treatments by hexametaphosphate in solution and when formulated into the dual-action whitening dentifrice. Similarly, plaque biofilm calcification was significantly inhibited by supernate treatments of the hexametaphosphate whitening dentifrice. The activity of hexametaphosphate dentifrice in plaque biofilm calcification protocols exceeded that produced by commercial dentifrices containing polycarboxylic acid, metal ion and pyrophosphate tartar control ingredients. Results predict excellent clinical activity for hexametaphosphate dentifrice for the prevention of supragingival calculus formation. Published double-blind, randomized clinical studies confirm the validity of these laboratory models for the screening of potentially improved tartar control ingredients.