4-Day Plaque Study with Two Chewing Gums in Adult Volunteers

Objective: The objective of this study was to evaluate the efficacy of a chewing gum containing 0.2% zinc citrate to reduce plaque growth compared to a gum without zinc citrate. Methods: Twenty five healthy adult volunteers completed the 2-cell cross-over, double-blind study. Subjects were randomly assigned to the order of using the two gums. Each test phase consisted of 4 days product use. At the start of each phase, the buccal/lingual surfaces of all teeth were cleaned. During the test phase, subjects chewed two pieces of gum on five occasions per day. No other oral hygiene was allowed. Disclosed plaque was recorded at the start and end of each test phase according to Turesky et al (J Periodontology, 1970, 41:41-43) on the lingual and buccal surfaces of all teeth. The outcome variable was the mean plaque score after four days of chewing gum. The null hypothesis of no difference between the two groups was tested against the alternative hypothesis that the zinc citrate gum reduced plaque accumulation compared to the control. Results: After using the zinc citrate gum the mean plaque index was 0.76 (std.dev=0.43); after using the control gum the mean plaque index was 1.73 (std.dev.=0.63). The difference between the two gums was 0.97; this difference was statistically significant (p<0.001, ANOVA). Plaque growth (i.e. final score minus starting score) was 68% lower after using the zinc citrate gum compared to the control gum (p<0.001). Conclusion: Chewing gum containing 0.2% zinc citrate reduces plaque growth, and can contribute in this way significantly to the prevention of plaque-mediated oral diseases such as caries and gingivitis.