In vivo Efficacy of an Alcohol-free Essential Oil Containing Mouthrinse

Objective: The purpose of this study was to determine the potential of LISTERINE® ZERO™, an alcohol- free essential-oil (AFEO) mouthrinse, to reduce the number of total anaerobic and malodor associated volatile sulfur compound (VSC) producing microorganisms in the mouth after a single use. Methods: This was an IRB-approved, single-use, randomized, observer-blind, single-center, supervised, controlled, parallel-design, clinical trial assessment of the in vivo germ kill potential of an AFEO mouthrinse versus a brushing control. 37 generally healthy subjects meeting inclusion/exclusion criteria were accepted so that 30 subjects would reasonably be expected to complete the study. Subjects entered a normalization period for 5-7 days of brushing with assigned toothbrush and fluoride toothpaste twice daily. Subjects were randomized into a brush group or a brush and rinse group. At baseline, subjects rinsed with 5 ml of water for 10 seconds and collected expectorant plus 1 ml unstimulated saliva in a sterile tube. Subjects brushed their teeth with fluoride toothpaste for 1 minute and expectorated. Subjects rinsed with 5 ml of water for 10 seconds and collected the expectorant in a sterile tube. Subjects in the rinse group then rinsed with 20 ml of test product for 30 seconds and collected the expectorant. All expectorant samples were analyzed for total anaerobic and VSC organisms by spiral plating on TSA with blood or OOPs III agar. The CFU/ml from the AFEO mouthrinse were compared to baseline to quantify reduction. Results: The AFEO mouthrinse reduced total anaerobic organisms by >100 million CFU/ml and VSC producing organisms by >40 million CFU/ ml versus baseline. Conclusions: The results of this study demonstrate that the AFEO mouthrinse, when used as an adjunct to brushing kills anaerobic and VSC organisms by millions on contact.