Comparison of Anti H2S-forming Bacteria Effect of Two Dentifrices

Objectives: To evaluate the oral malodor control efficacy of a new Zinc citrate dentifrice vs. a commercial Triclosan/Gantrez dentifrice on H2S-forming bacteria. Methods: Following one week washout period of brushing with regular fluoride toothpaste, 26 healthy human subjects reported to the clinical site without performing oral hygiene, eating or drinking in preparation for a baseline tongue coating collection. After providing tongue coating, subjects were randomly assigned brushing with test dentifrice (2% Zinc Citrate or 0.3% Triclosan/Gantrez dentifrices) one week twice daily. In the morning of the eighth day, subject reported to the clinical site and brushed with 1.5g the same test dentifrice for 3 minutes without brushing the tongue. After brushing, subjects are refrained from eating and drinking for 3 hours, and then return for 3-Hr post brushing evaluation. The cross-over procedure was repeated to use a different dentifrice following a second washout phase. Each tongue coating sample was serially diluted four times (1:10) in sterile water. The fourth dilution was plated, in duplicated on agar plate containing lead acetate to enumerate H2S-producing bacteria. After incubate for 72 hours at 37°C, the dark colonies representing H2S-forming bacteria on lead acetate agar were counted. For each product, a paired t-test was performed to compare 3-Hr post-use to baseline and a two-way analysis of variance with subject and product as effects was performed to measure the significance of the difference between the test products. Results: Both Zinc Citrate and Triclosan/Gantrez dentifrices showed comparable results in reducing the growth of H2S-forming bacteria after 3 hours post-brushing. There was no statistically significant difference between the two dentifrices. Conclusions: This study results suggest the new Zinc Citrate dentifrice and the commercial available Triclosan/Gantrez dentifrice provide a comparable efficacy for reduction of H2S-forming bacteria from the tongue, which contributes to the benefit for oral malodor control.