Lowenberg, whose patients include top models (Kate Moss, Claudia Schiffer, Naomi Campbell, Cindy Crawford), actors (Courteney Cox Arquette, Chris Rock) and beauty pros (Kevyn Aucoin), happily accepts the suggestion that he's a major reason the bar is being raised on smiles. "The stakes are indeed higher," he says. "But having your teeth 'done,' as we call it, can have a more dramatic effect than any other cosmetic procedure."

Lowenberg and his colleague Gregg Lituchy devote about 75 percent of their practice to doing porcelain veneers—which they call "smile makeovers," because they reshape not just the teeth, but the whole mouth. Eighty percent of their clientele is female, but men are also starting to consider such services a practical option to neaten their look.

"The wonderful thing about veneers," explains Lowenberg, "is that you can do anything: You can make crooked teeth appear straight. You can make shorter teeth look longer. You can make longer teeth look shorter. You can close spaces. You can change color, size, spacing, shape and position. Veneers allow you to create an optical illusion. If they were doing this two decades ago, I doubt Lauren Hutton or David Letterman would have kept the gaps in their teeth."

Veneers cost between $10,000 and $40,000—considerably more than fees for bleaching, which are usually between $300 and $1,000—but the rewards are greater and without the