Comparative Antimicrobial Activity of Essential Oil-Containing Oral Care Strips

INTRODUCTION: Previous work demonstrated antimicrobial activity of mint flavored essential oil-containing oral care strips against oral malodor organisms in a novel in vivo germ kill model (Abst. #577, IADR 2000). This research assessed the in vivo antimicrobial activity of three different flavor variants of Listerine PocketPaks^® (CoolMint, FreshBurst and Cinnamon) against oral malodor organisms. METHOD: The randomized, controlled, observer-blind, crossover studies compared the effect of formulations to no-treatment control 90 minutes following single use. Approximately 50 subjects participated in each study. Baseline recoverable microbial counts were assessed by sampling the right side of each subject’s tongue with a sterile swab, which was placed in 0.1% peptone broth, diluted and plated on selective medium. The assigned oral care strip was dissolved on the left side of the subject’s tongue, which was sampled 90 minutes later. The primary efficacy variable was the log10-transformed number of dark pigmented (volatile sulfur compound-producing) microbial colonies averaged over duplicate plates. 48-hours later, subjects received the alternate treatment(s). Two initial studies compared mint flavor strips to no-treatment control only. Two subsequent studies assessed spearmint and cinnamon formulations compared to no-treatment control, with the mint formulation as a positive control. RESULTS: In all studies, three flavor variants of essential oil-containing oral care strips significantly (p < 0.001) reduced recoverable counts of odor-causing microorganisms compared to no-treatment control. The mint formulation provided significant reductions in odor-causing organisms ranging from 66.3% to 74.7%. Spearmint and cinnamon formulations reduced odor-causing organisms by 64.3% and 76.7%, respectively. CONCLUSIONS: These studies demonstrate the validity and reproducibility of the in vivo germ kill model to assess antimicrobial activity of mint flavor essential oil-containing oral care strips. Further, these studies demonstrate that minor flavor variations do not interfere with the ability of essential oil-containing oral care strips to significantly reduce and control oral malodor-associated microorganisms.