The surfaces of the teeth (enamel) contains millions of microscopic pores and over time organic compounds from food, drink, tobacco etc penetrate these pores and enter the dentine causing discoloration.
The whitening gel whitens the teeth by delivering oxygen into the dentine layer of the tooth through the enamel which just acts as a window. The oxygen then breaks down the organic compounds trapped in the dentine into smaller lighter particles which reflect light better thereby lightening the colour of the teeth.
The LED (Light Emitting Diode) light simply accelerates the process by forcing more oxygen into the dentine than would be the case otherwise. Results can be dramatic and clients may see up to 14 shades difference. The process carries on working for a full 24 hours after the treatment so the full effect is not seen straight away. This is why clients are always asked to refrain from eating or drinking any teeth staining food or drink for 24 hours. Smokers are also asked to refrain if they can, for at least 8 hours following the treatment. The process does not alter the tooth structure in any way.