OBJECTIVE To evaluate the efficacy ofa stannous fluoride dentifrice as compared to a negative control dentifrice in the reduction of dentinal hypersensitivity after immediate use, and after three days and two weeks of use. METHODS This was a controlled, randomized, examiner-blind, two-treatment, parallel group study conducted among healthy adult male and female subjects with moderate dentinal hypersensitivity. Subjects with at least two sensitive teeth demonstrating reproducible sensitivity to both thermal stimuli (SchiffAir Sensitivity Scale score of > 1) and tactile stimuli (Yeaple probe 10 grams) were randomized to treatment with either a 0.454% stannous fluoride (SnF,) dentifrice (experimental group) or a 0.76% sodium monofluorophosphate dentifrice (negative control group). At baseline, subjects received an oral soft tissue examination, were assessed for tooth sensitivity, and were instructed, according to manufacturer's product instructions, to brush with their assigned dentifrice thoroughly twice a day (morning and evening). Subjects performed their first product use on site under supervision. Immediately following the first treatment, both examiner and subject assessed sensitivity to thermal stimuli for each enrolled tooth using the Schiff Air Sensitivity Scale and air visual analog scale (VAS), respectively. Thermal sensitivity was also assessed (by both examiner and subject) at the Day 3 and Week 2 study visits, together with tactile sensitivity (Yeaple probe) and oral soft tissue exams of the mouth. RESULTS One-hundred and eleven subjects were enrolled and randomized to one of the two treatment groups. Immediately after the first use, the SnF, dentifrice provided statistically significant (p < 0.0001) reductions in sensitivity relative to the negative control dentifrice of 13.8% for the thermal Schiff Air Sensitivity Scale and 14.6% for the air VAS. The SnF, dentifrice also provided statistically significant (p < 0.0001) reductions in sensitivity relative to the negative control at Day 3 and at Week 2 based on the thermal Schiff Air Sensitivity Scale (31.8% and 61.3%, respectively) and the thermal air VAS (34.8% and 66.6%, respectively). For the tactile Yeaple probe, the SnF2 dentifrice demonstrated significantly (p < 0.0001) better sensitivity scores relative to the negative control at Day 3 and Week 2, with improvements of 186% and 239%, respectively. Both dentifrices were well tolerated. CONCLUSIONS An experimental 0.454% SnF2 dentifrice provides significantly better immediate and ongoing sensitivity relief relative to a negative control dentifrice.