It probably doesn't rank up there with Ali-Frazier or the Coke and Pepsi "cola wars," and maybe not even whether "lite beer" is less filling or tastes great, but Pfizer (NYSE:PFE) and Procter & Gamble (NYSE:PG) are launching battle plans for control of your mouth, and you should come out of it with a brighter smile and fresher breath.

Listerine is Pfizer's mouthwash muscle in the battle, the dominant brand with a 53% and growing market share. Scope, from Procter & Gamble, is a distant second with just 12%, but the company has thrown in a ringer by introducing Crest Pro-Health Rinse this month. This new contender, planned for a decade, uses the Crest brand name and a non-alcohol-based formula to challenge Listerine's dominance.

The line in the sand differentiating the two products is alcohol. Listerine uses it to activate essential oils in the mouth that allow it to fight gingivitis, germs, and plaque. Procter & Gamble's Crest mouthwash will use a special formulation of the chemical cetylpyridinium chloride (or CPC), a mouthful in itself and originally a breath freshener, to kill germs.

Crest says the intense alcohol taste associated with Listerine causes users to either dilute it or not use enough of it, thus minimizing its benefits. Listerine points to studies showing that users like the tingling sensation they get from the mouthwash and says that not only does CPC cause staining, but also no CPC-based mouthwash has ever received the coveted American Dental Association's Seal of Acceptance. Listerine has garnered the Seal. Crest counters that all antimicrobial mouthwashes -- including Listerine -- can potentially stain teeth but that stains can be controlled with a tartar-control or whitening toothpaste.

Obviously, the companies are baring their sharp dental implements at each other.

While Crest will be taking it to Listerine's home court with the mouthwash, Pfizer is about to cut its teeth on a tooth-whitening "pre-brush" that seeks to build on Listerine's brand power. Crest, with an assortment of whitener products from toothpaste to strips to paint-on gels, is locked in a battle with Colgate-Palmolive (NYSE:CL), which has the No. 1 toothpaste. Listerine Whitening Pre-Brush Rinse (which makes CPC sound like a Dick-and-Jane book) doesn't attempt to make the same plaque- and gingivitis-fighting claims that regular Listerine does, and in fact, the company says it should be used in combination with its mouthwash. Pfizer expects three-quarters of the sales from the new product to be incremental to the brand.

The mouthwash market is a surprisingly large and somewhat staid. Sales totaled about $600 million in 2004, only some 5% higher than in 1999. Not exactly a high-growth market. And that's why it has been so difficult to unseat Listerine from its perch. Though the companies didn't break out how much each brand contributed to its bottom line, Pfizer reports that its consumer health care segment saw revenues increase 19% to $3.5 billion. Procter & Gamble reported that its Oral Care segment had a sales jump of 18%, although market research company Euromonitor said sales of Crest toothpaste slipped last year by 11.5%, to $162 million. The entire oral-care market exceeded $4.3 billion in sales last year.

The battleground of your mouth is as intense as Listerine's flavor is sharp. Both competitors face growing threats from Church & Dwight (NYSE:CHD), Gillette (NYSE:G) (soon to be a part of Procter & Gamble), and even GlaxoSmithKline (NYSE:GSK).

For anyone who has worked in close quarters with someone who is less than circumspect about his or her oral hygiene, we can only hope they are all successful.

Both Pfizer and Colgate-Palmolive are Motley Fool Inside Value recommendations. To see which other companies analyst Philip Durell has highlighted as good values, take a free 30-day trial today.

Fool contributor Rich Duprey has been told that his morning breath is reminiscent of honeysuckle carried on a dew-dripped spring breeze. He does not own any of the stocks mentioned in the article.