The Complaint Since you got your teeth whitened, your pearlies ache when you eat ice cream or sip that hot latte. That's because whitening treatments with high concentrations of carbamide peroxide or hydrogen peroxide penetrate tooth enamel and temporarily expose the tooth's pulp, which contains nerves. You can wait a few days for the resulting sensitivity to start subsiding on its own. Or for $12.50, you can try Orajel Advanced Tooth Desensitizer -- the first over-the-counter dental product to contain 2-hydroxyethyl methacrylate. The paint-on pain blocker seals porous tissue surrounding the pulp, protecting the nerve from heat and cold, said Orajel spokesman Chris Kammer, a Madison, Wis., dentist who specializes in whitening.

The Tooth Hurts Dentists have for years used 2-hydroxyethyl methacrylate and the product's other active ingredients to treat sensitive teeth and coat teeth before placing veneers or filling cavities, Kammer said. And, he added, lots of dental-office tooth-whitening products now include similar desensitizers, heading off pain before it occurs. A treatment (for $12.50 you get three, each supposed to last up to 28 days) involves two close-together applications; don't eat or brush for an hour after applying. The OTC product is supposed to start working within a day. Apply carefully; it can irritate gums, lips or other soft tissue.

You Know the Drill American Dental Association spokesman Matt Messina said folks whose teeth, whitened or otherwise, hurt for more than a day or so should check with a dentist. "You don't want to [use a product like this] to mask something that needs professional attention," like a cavity or gum disease, he cautioned.

-- Jennifer Huget