In 2005, a federal judge forced Listerine to pull ads that claimed the mouthwash was clinically proven to be as effective as floss in fighting tooth and gum decay. In a lawsuit filed by a dental floss manufacturer, U.S. District Judge Denny Chin concluded, "Pfizer’s implicit message that Listerine can replace floss is false and misleading.”
According to Chin, “substantial evidence” demonstrated that rinsing with a mouthwash is not as effective as flossing. A representative for Pfizer, which owned Listerine at the time, declined to comment on the suit.