The scourge of yellow and stained teeth used be looked upon as almost a right of passage–once you became an adult, it was generally assumed your teeth would reflect the wear and tear of coffee, tea, wine, smoking, or just plain living. But less-than-pearly whites are now considered cosmetically damaging, something to be scrubbed, bleached, or zapped away. Toothpastes, gels, dentists, and even kiosks in the malls offer teeth whitening solutions. Almost all of them claim to be safe, but are they really? I’ve seen what happens when you bleach a T-shirt–it usually makes the fabric thin and weak–so what happens to our precious teeth when we bleach them back to our cream-colored past?

Fighting Tooth and Nail
Teeth whiteners work in two general ways, either through surface polishing or through bleaching the tooth and this makes all the difference in their effectiveness and side effects.

Most over-the-counter whitening toothpastes are non-bleaching, meaning they physically or chemically remove surface stains but leave the natural color of your teeth intact. They are often referred to as dentifrices and contain abrasives that polish the tooth or non-bleach chemicals, like sodium tripolyphosphate, that help remove stains. In general, whitening toothpastes can lighten the color of teeth slightly, but won’t be able to make them an entirely different color.

The other way to whiten teeth is through bleaching products, which contain peroxides that can change the intrinsic color of the tooth in addition to removing surface stains.

Many people know that brushing with a diluted solution of hydrogen peroxide can help lighten teeth and this is essentially the same mechanism working in bleaching products. Over-the-counter home-based gels and solutions contain around 10 percent carbamide peroxide, which breaks down into hydrogen peroxide and then bleaches the teeth.

Professionally applied teeth whiteners work in the same way, but their peroxide concentrations are higher, ranging from 15 to 35 percent. Sometimes they’re used in combination with a laser. While at-home methods usually involve strips that you’re supposed to apply for an hour or so over the course of a few weeks, professional treatment takes an hour or so. Safe or Silly?

Whitening toothpastes are generally considered safe, though people with gum or tooth erosion might want to consult a dentist before using. Teeth bleachers, on the other hand, do come with risks.