(Business 2.0) – When Jim Cali talks about his $40 million R&D facility and his crack engineering team, you'd think he had built a Trident submarine. "It was a skunk-works project," he says. But Cali, head of commercial strategy for the confections division of Cadbury Schweppes Americas, is referring to Trident Splash, a new sugarless gum that took Cadbury's 100 "gumologists" three years to perfect.

Not long ago, U.S. gum sales were falling. But thanks to a high-tech battle for supremacy, the market has ballooned 15 percent since 2003 to $2 billion, according to Information Resources. Last year gum makers introduced 257 new varieties, and leaders Cadbury and Wrigley are experimenting with gums that do everything from clean teeth to soothe upset stomachs. Drugmakers, including Denmark's Fertin, are also eyeing the century-old category as a way to treat obesity and migraine headaches. Here's a look at what else is popping. -- MATTHEW MAIER

Liquid-Center Gum

Trident Splash (Cadbury Schweppes Americas) 2005 sales: $3.5 million (released in October) Each piece of Splash is a hard-coated pellet with a liquid center, so it delivers two flavors in every bite. Sold in peppermint-vanilla and strawberry-lime, it's the first liquid-filled gum aimed at adults.

Wellness Gum

Airwaves Active (Wrigley) 2005 sales: Not available Introduced last year in France and sold in 14 European and Asian countries, Airwaves contains vitamins and ingredients such as guarana that are said to aid the immune system.

Caffeinated Gum

Jolt Caffeine Energy Gum (GumRunners) 2005 sales: $2.7 million Founded by two former Colgate-Palmolive execs, GumRunners licensed the brand name of the heavily caffeinated cult beverage to create Jolt gum, which packs a coffee cup's worth of caffeine into two chewable pieces.

Whitening Gum

Orbit White (Wrigley) 2005 sales: $49.7 million Launched in July 2004 as an extension of Wrigley's blockbuster Orbit brand (which did $235 million in sales last year), Orbit White contains sodium bicarbonate to keep teeth white and prevent plaque buildup.

Nicotine Gum

Nicorette (GlaxoSmithKline) 2005 sales: $171.3 million The nicotine-enhanced gum, sold for about $40 a pack, helps ease the cravings of smokers trying to kick the habit. Nicorette was one of the first gums to be used as a drug-delivery vehicle; it's now the undisputed leader in the U.S. nicotine gum market.

Source: Information Resources (sales figures)