An evaluation of the effects of ARM & HAMMER DENTAL CARE The Baking Soda Gum on extrinsic dental stain was performed on 85 subjects presenting with measurable extrinsic stain. The subjects were randomized to use either the baking soda chewing gum or a breath mint placebo once daily after lunch while brushing once daily. The chewing gum was chewed for 20 minutes for each use and the breath mint was kept in the mouth until completely dissolved. The subjects were instructed to brush once daily to simulate the level of hygiene normally practiced by subjects, thereby avoiding the well-reported Hawthorne effect experienced in clinical trials instituting twice-daily brushing. Examinations postbaseline were performed after 2 and 4 weeks. The reduction in measurable extrinsic stain in the baking soda gum group vs the breath mint control was statistically significant at 2 weeks (P < .0002) and at 4 weeks (P < .0008). Statistical analysis of the data revealed a significant change in extrinsic stain from baseline for both groups. The magnitude of the unadjusted longitudinal reduction in extrinsic stain in the baking soda gum group was 51% at 4 weeks.