Cool Mint Listerine Mouthwash 6 - 1.5 Liter Bottles. Listerine was shown in a clinical study to reduce 52% more plaque and 21% more gingivitis than brushing and flossing alone. Listerine is the only nationally branded antimicrobial mouthwash to receive the ADA Seal of Acceptance for fighting plaque and gingivitis. Package of 6 - 1.5 liter bottles