Cool Mint Listerine Mouthwash 2 - 1 Gallon Bottles and Pump. 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. PROFESSIONAL SIZE FOR USE BY DENTISTS AND DENTAL HYGIENISTS.