Who would have predicted that the toothbrush, used in one of life's most annoying personal hygiene routines, would become one of the hottest trend indicators in America? According to design mavens, toothbrushes are now in the vanguard of consumer product design, becoming to teeth what athletic shoes have been to feet.

"It's incredible," says Mark Dziersk, chairman of the board of the Industrial Designers Society of America. "There's more design in a toothbrush today than in the first space shuttle."

For decades, a toothbrush was just a toothbrush. It had bristles, it had a handle, it came in a few colors. It performed its function admirably, didn't call attention to itself, and slipped obligingly into the porcelain holder that protrudes from bathroom walls.

Now check out the "oral care" department in your pharmacy. Toothbrushes come with power tips. Gum bumpers. Pivoting heads. Gum massaging bristles. Zig-zag bristles. Multi-level interior bristles. Flared side bristles. End rounded bristles. "Indicator" bristles that fade so you'll know when to change your toothbrush.

They come in right-handed versions and left-handed. They are sculpted, amorphous, multicolored, and multitextured. They come with rubber grips and "squish" grips, curved handles to offer "better hand action," and flexible necks that bend to absorb brushing pressure." They have names, like pets: "Navigator," "Wave," "Scuba."

They're famous, too. The $9 oversized Radius model, the T. rex of toothbrushes overflowing with "6,500 soft hexagonal" bristles, has been featured in trendy InStyle Magazine and is in the permanent collection of the Smithsonian Institute National Design Museum.

For decades, until the mid-1980s, the toothbrush changed so little that bathrooms were designed around their standardized shape. Now just try and find one that will fit into the holes of your bathroom holder, "a structure that now juts forlornly out of the wall, a porcelain tomb to America's dental-industrial past," observes I.D. Magazine, the design publication, which runs a juried competition for consumer products. I.D. has given design awards to two toothbrushes: the Colgate Palmolive Grim'Ems brush for children (I.D. hailed its "squishy tactility") and Oral-B's CrossAction toothbrush for its "breakthrough head technology," the jurors said.

Oral-B, a division of the Boston-based Gillette Company, has "dozens" of toothbrush models in a range of colors, bristle patterns, sizes, and handle designs, according to Nicola Pugliese, spokeswoman for Gillette's Oral Care Division, which does over $1 billion in sales a year.

And it's still rolling them out: In February, the company is introducing an ambitious line of children's toothbrushes, "Stages," with four separate models "ergonomically" designed (in Stage 1) for the parent's hand, and graduating (in Stage 4) to a "unique bristle design to clean complex and changing pre-teen teeth." (Not to be confused with Radius's new quartet of children's toothbrushes in various degrees of softness and grip-ability, designed for Fisher-Price.)

Dr. Howard Needleman, a pediatric dentist at Needham's Chestnut Dental Associates, still hands out old-fashioned, no-frill toothbrushes to his patients, though he admits they're not much of a draw anymore. "We find them in the parking lot, and in the garbage," he says, where patients have discarded them.

In a country that's given us fruit-colored computers and flower vases in cars, it's not completely surprising that consumers' appetite for design would extend to the things used for scraping their teeth. Still, there's something counter-intuitive about the way toothbrushes have been revolutionized. Surely, Americans had teeth before this upscale toothbrush phenomenon, and their teeth got brushed and mostly didn't fall out. Is the world a better place for refined bristle technology?

"I think it's about very real things," says Kevin Foley, president of Radius, whose toothbrushes brush the teeth of Sting, Robert Redford, Jane Fonda, and Cher, according to the Radius Web site. "People are very vain, their teeth are really important to them. Look at the sales of whitening toothpaste. People want their teeth to be white."

They also want more mouth-friendly toothbrushes, he says. His company's research, conducted in the 1980s, showed that "people hated their toothbrushes, and they don't hate Radius. It has a very big handle, which means you don't have to grab it tightly, to guide it in your mouth. You don't have to apply a lot of pressure. And it works better because it has softer bristles. We use thin nylon that doesn't get destroyed. They last about three times longer than regular toothbrushes."

According to Dziersk of the Industrial Designers Society, toothbrush mania is part of a more pervasive design revolution that started about six years ago. He calls it the new "Golden Age of Design," which started with the iMac and Volkswagen beetle and has infiltrated even the Targets of the world, purveyors of Michael Graves-designed kitchen utensils, from spatulas to can openers.

"In Europe, it has been pervasive for a long time," Dziersk says. "Only now in the United States is the dialogue at a high enough level that we can even compete. What's happened is that design has become the competitive business leverage for companies to sell products. In the 1970s, it was marketing. In the '80s, it was finance, with merger mania and all those leveraged buyouts. Then it was distribution, when all the Wal-Marts were created. Now it's design's turn to decide which product you are going to choose."

Toothbrush companies assert there is more to high-end toothbrushes than competitive business leverage. "We make better products and consumers get better teeth for life," says Kathy Grealish, vice president of marketing research for Gillette's Oral Care division. "It's a win-win for everybody."

Still, the dental profession seems skeptical. "In the end, a lot of this is advertising," says Needleman, the Needham dentist. "It's one company trying to one-up the other. We have designer braces now. Designer jeans. A lot of it is corporate America trying to find products that get everyone's attention."

"We say floss once a day, brush twice a day," adds Dr. Clifford Whall, director of product evaluations for the American Dental Association. "There are an awful lot of brushes out there effective in removing plaque. I can't say any one is better than any other."

By all accounts, toothbrushes are only going to get more exotic. "I believe (the design-driven economy) has got another five years," says Dziersk, whose Chicago design firm, Herbst, Lazar, Bell Inc., has done ergonomic research in toothbrush design and toothbrush packaging.

What's next for toothbrushes?

Make room in your toothbrush holder for "metallics," he predicts. "Titanium and aluminum. I'd call it the next big trend. You wait and see."