There are many causes of tooth discoloration, ranging from natural tooth genetics to diet, oral hygiene habits, smoking, cavities, certain dental treatments, fillings, etc.
It is important the dentist identifies the cause to determine if whitening is appropriate and safe for your situation. Whitening will only work in some cases and if the correct products are not used properly it can cause permanent damage to your teeth and gums.
With this case tooth whitening was performed with daily use of professional whitening gel for a period of approximately 1 month using customized professional application trays. Whitening results vary from person to person but this is a typical example.
When used appropriately tooth whitening is a very safe, effective and lasting treatment.