5. The Gums Factor
Here’s one of the most important teeth whitening tips. Depending on the state of your gums, it may be aesthetically better not to bleach, since exposed roots cannot be bleached and will look different than the rest of the tooth.

6. Sensitivity
The 10% carbamide peroxide solution used in at-home trays or the 35% can cause tooth sensitivity in individuals whose enamel is already compromised.