Light Therapy

You might have seen this gadget on TV. Light-based teeth whitening systems claim to whiten teeth up to five shades in as few as five days. "A peroxide-based whitening solution ampule is filled into a mouthpiece that contains a molded flexible circuit with activating light and heat," Smigel says. "The mouthpiece is placed over teeth for an eight-minute session. The 'activating light' is said to speed whitening results without tooth sensitivity." After four initial 32-minute sessions in the first three to five days, you can then maintain results with a total of 32 minutes per month.

"In my opinion, these products are not realistic," Smigel says. "The light used is an LED light, and there has been no conclusive research that any of these at-home teeth whitening lights are effective. Not to mention that the systems themselves can be quite costly."

Glo Brilliant Personal Teeth Whitening Device, $199, available at Sephora.