A new stabilized stannous fluoride dentifrice, currently marketed as Crest Gum Care has been examined for its effects on intrinsic plaque metabolic and regrowth activity and effects on plaque resistance to SnF2 throughout nine weeks of toothbrushing. Subjects brushed their teeth 1 X, 2 X or 3 X/day with stabilized stannous fluoride dentifrice or placebo dentifrice for nine weeks, presenting in the morning on weeks 3, 6-9 for plaque sampling. Following nine weeks, subjects were crossed-over and repeated the experiment on their alternative assigned product (active SnF2/placebo). Sampled dental plaques were evaluated for standardized glycolysis and regrowth activity using the "Plaque Glycolysis and Regrowth Method" (PGRM). Following the second nine-week treatment period, subjects concluding either placebo or SnF2 toothbrushing participated in a single-treatment PGRM experiment using stabilized stannous fluoride dentifrice. Toothbrushing with stabilized stannous fluoride dentifrice in this experiment produced significant and sustained reductions in both plaque glycolytic and regrowth activity as compared to placebo treated plaques. In the concluding single-brushing PGRM experiment, SnF2 dentifrice was shown to produce equal inhibitory actions in plaque from subjects completing stannous fluoride or placebo treatments. This result confirmed that nine weeks toothbrushing with stabilized stannous fluoride dentifrice produced no development or resistance of plaque to SnF2 inhibition. These results support the strong in vivo antimicrobial actions of the stabilized stannous fluoride dentifrice, Crest Gum Care.