What does ‘bleaching’ a tooth mean?

Bleaching or whitening is a process that lightens teeth discolorations using whitening agents. The active ingredient in most of the whitening agents is carbamide peroxide, also known as urea peroxide; when water contacts this white crystal, the release of hydrogen peroxide lightens the teeth. Tooth discolourations are commonly caused by consumption of certain coloured substances (coffee, tea, colas, tobacco, etc), trauma, tetracycline, excessive fluoride, pulp degeneration, and old restorations. The bleaching techniques have variable results, depending on the case and degree of discolouration, and may need to be redone after a period of time.  more