The Deal

• $139 for one in-office teeth-whitening treatment ($400 value)

Teeth Whitening: More Than a Superficial Change

Whitening treatments involve more than just the surface of the teeth. Read on to reveal the science behind a brighter smile.

Every time you brush your teeth, abrasive compounds and chemicals wear away small particles, leaving a cleaner surface. If toothpaste doesn’t seem to get at yellowish stains, that’s because they’re not actually on the surface—they’ve seeped into the dentin, the more porous layer between the enamel and the small diamond at the root of each tooth. To reach this deeper discoloration, scrubbing won’t work. Instead, dentists must deploy some basic chemistry. In most whitening systems, a solution of hydrogen peroxide (or carbamide peroxide, which turns into hydrogen peroxide when it encounters saliva) is left to sit against the teeth in the form of gel-filled trays or strips. Then the peroxide sets to work breaking the chemical bonds of the particles that contain unwanted coloration.

Some formulas are designed to be activated with an LED, laser, or halogen light whose specific wavelength is supposed to accelerate the breakdown of these particles. Although studies as to the light’s effectiveness vary between manufacturers, the basic chemical process remains the same, and dentists who use light-activated systems suggest that they can work more quickly.