Gum, for a lot of reasons, isn't selling. Sugarless gum sales fell 6.6% to $2.7 billion in the year ending July 14, according to IRI. Wm. Wrigley Jr. Co. and Mondelez International, appear to be coming up with two different approaches. Mondelez will emphasize benefits such as oral health. Wrigley's newest campaign for Extra, the marketer's second-largest gum brand behind Orbit, debuts with a TV spot that puts Extra at the center of emotional moments between a father and daughter.