Many whitening gels contain water—some more than others—in order to help prevent sensitivity and minimize shade relapse caused by dehydration. When we whiten our teeth, the hydrogen peroxide or carbamide peroxide in the whitening gel have a drying effect on the teeth, causing the teeth to appear very white and potentially become sensitive. Use of a light or laser will further dehydrate the teeth, increasing the chances of sensitivity and providing an exaggerated whitening result that will relapse. By using a product with high water content, we help to combat dehydration while whitening.
Once you've completed your whitening treatment, your teeth will begin to rehydrate. Sensitivity should subside, and the teeth may have a less-white appearance due to any shade relapse caused by dehydration. For this reason, it is best to avoid using in-office whitening treatments that require the use of a light or laser. It's better to use a whitening product with a high water content, such as Opalescence whitening products, which contain at least 20% water.