Oh, those gleaming white teeth. Whiter than a picket fence. A Tic Tac. A porcelain toilet. They blind us from billboards, bedazzle us from screens and make us squint at magazines. How can we ever compete? With bleach, of course, courtesy of our dentist, "whitening spas” and a battalion of over-the-counter concoctions: white strips, age-defying chewing gum, paint-on gels, leave-in trays, even brightening toothpaste and mouth wash.

“I’m obsessed,” says Jamie Burkhart, a 23-year-old college student from Cleveland, and self-proclaimed “bleachorexic” who has been brightening her smile for about a year with Crest Whitestrips. “I have ridiculously white teeth, but I still don’t think they’re white enough.”

Teeth whitening is the No. 1 requested cosmetic service today and its popularity continues to soar, according to the American Academy of Cosmetic Dentistry. Outside the dentist’s office, it’s every bit as popular. Americans spent more than $1.4 billion on over-the-counter teeth-whitening products last year alone.

But as successful and satisfying as bleaching has proved for the millions of Americans looking to instantly boost their confidence, hide their age and/or keep up with the Catherine Zeta-Joneses, some have found it to be a real pain. Even worse, those who take it too far may end up doing real damage.

“There are people who can never get enough,” says New York City dentist Dr. Irwin Smigel, president of the American Society for Dental Aesthetics. “I’ve had situations where people have needed root canals because they’ve overbleached, where tissues were damaged. You can wear away some of the enamel and your teeth will become translucent and unnatural. They’ll become blue or blue gray.”

Burn, baby, burn

And then there's the burn. A study in the Journal of the American Dental Association found half of people who bleached their teeth experienced temporary sensitivity from whitening treatments, everything from mild tingling to burning gums to knee-buckling “zingers” and/or extreme sensitivity to sound or even air.

Meredith Kummell, 32, of San Francisco says she was “popping Advil like candy” after her BriteSmile session, an in-office whitening procedure that uses a special lamp coupled with a light-activated bleaching gel.

“It wasn’t the most pleasant experience, but I don’t regret it,” she says. “I’m pretty vain and this is something about yourself that you can fix for a reasonable amount of money.”

Unfortunately, sometimes we take that “fix” too far.

Burkhart, the college student, just piles on more Crest Whitestrips whenever she feels the need for a retouch. Her first “touch up”? Three months after her initial 14-day treatment. (According to the package, one bleaching session should last for a year).

But she’s not worried about gambling with her dental health. “My roommates and I joke that our teeth are going to fall out when we’re 32 and we’re going to have veneers,” she says “But it doesn’t really faze me.”

Your teeth won’t fall out, assures Martin Zase, president of the American Academy of Cosmetic Dentistry and a dentist in Colchester, Conn. “All of the products used in the dentist office are safe and most of the [over-the-counter] products are safe as well, but there are a few that are acidic and acidic products increase the likelihood of decay if you overuse.”

Bleachers should aim for a color that matches the whites of their eyes, he suggests. And they should also make sure they consult with a dentist, even before using over-the-counter products, because those who go it alone often end up going too far. “Your teeth look better so you do it some more and you don’t know when to stop,” Zase says.

Carol Ann O’Keefe, 51, of Seattle, can speak to that. Like many baby boomers, she decided to tap her dentist for at-home bleaching trays in order to remove years of accumulated smoke, coffee and wine stains from her teeth. But the temptation proved too much. “You were supposed to do it three times a day for an hour or two each time, but that was kind of a pain in the butt so I thought, I’ll just do it overnight,” she says.

The result?

“After six months, my teeth started to get like a pearl look,” she says. “They looked thin, like if you put a light behind them, you could see through them. I thought if a little bleach is good, a lot must be really good, but it’s not that way. Your teeth will never be porcelain white, like your toilet.”

That Hollywood smile

But why would we even want our teeth to look like our plumbing fixtures?

“I hold ‘Laguna Beach’ responsible,” says Kummell, the Advil-popping teeth bleacher. 'Laguna Beach’ or ‘Survivor.’ They all have perfect teeth and when you see that constantly, you start to think, mine aren’t perfect.”

O’Keefe, who bleached to the point of translucence, points to gleaming white TV teeth, as well. “I see people like Jessica Simpson with these bright white teeth and I can’t figure it out,” she says. “My teeth will never be Oprah white.”

The problem is that few people’s will.

“What’s being sold to us is the image of the perfect Hollywood smile,” says Victoria Pitts, associate professor of sociology at Queens College, CUNY, and author of the forthcoming “Surgery Junkies: The Cultural Boundaries of Cosmetic Surgery.”

“But Hollywood smiles are full of veneers. They don’t simply bleach their teeth; they don’t have the original surface of their teeth. The standards are getting more and more impossible to achieve. Are we chasing a chimera? Absolutely.”

A quick glimpse at history shows white teeth have been on the agenda long before the advent of seductive Hollywood smiles and billion-dollar bleaching campaigns.

“People have been doing this for thousands of years,” says Dr. Scott Swank, dentist and curator for the National Museum of Dentistry in Baltimore, Md. “The Greeks had formulations and at the beginning of the Renaissance, Europeans were certainly putting compounds on their teeth in a conscious effort to whiten them."

Unfortunately, those compounds were essentially the equivalent of today’s Clorox. “It ate the enamel away,” he says. “They had whiter teeth for a while, but then they started to see severe decay.”

Thankfully, teeth-whitening technology has evolved. With any luck, our tendency to take a good thing too far will do the same — hopefully, before we end up actually needing to pop for those perfect Hollywood veneers.