IRVING (CBSDFW.COM) – Anna Phillips of Irving admits to craving a brighter, whiter smile.

“You just look well-kept and it just helps your overall appearance,” she says.

So, along with regular brushing, Phillips tried a do-it-yourself home teeth whitener, thinking that anything bought at the store must be safe.

“They’re not necessarily ‘unsafe’,” says Dallas Dentist Clark Steffens with Floss Dental, “but, they can be if used improperly.”

And Steffens says patients often can’t resist the urge to ‘over bleach.’ After all, says Philips, “couldn’t longer make it whiter?”

Well, she soon learned, longer can certainly make it more painful.

In spite of having flaunted the package instructions in the past, Phillips was in for quite a surprise when she fell asleep during a treatment.

“So I wake up the next morning with the strips still on my teeth… and my teeth are throbbing,” she said. “I’ve never had a cavity or anything like that, so that was probably the worst pain I’d ever felt in my mouth before.”

Phillips says her teeth hurt so badly that she couldn’t even smile.

But, it could have been worse. A quick Google search reveals story after story of patients recounting sensitive teeth and swollen gums after a teeth-whitening experiment gone wrong.

Steffens says even if patients prefer to use at home treatments, it’s best to consult a dentist first. And by all means, he says, know when enough is enough: Over bleached teeth can appear translucent.

“The other thing is, it makes teeth more porous, so if you bleach for too long and then you go out and end up having a glass of red wine that evening, it can actually make the teeth darker than they were when you started.”

And who wants that?