Lightness should last from one to five years, depending on your personal habits such as smoking and drinking coffee and tea. At this point you may choose to get a touch-up. The retreatment time is much shorter than the original treatment time.
The active ingredient in most of whitening agents is carbamide peroxide; when water comes into contact with this white crystal, the release of hydrogen peroxide lightens the teeth.
Several studies have proven bleaching to be safe and effective. The American Dental Association has granted its seal of approval to some tooth bleaching products. Some patients may experience slight gum irritation or tooth sensitivity, which will resolve when the treatment ends.   _{Your Comment}