• Tetracycline (antibiotic) staining.
• Excessive fluoride.
• Trauma (injury) to the teeth.
• Pulp (nerve) degeneration.
• Restorations (silver, gold).
• Genetic and acquired illnesses.
• Aging.
• Food, drinks (such as coffee and tea), and tobacco.

Your molds are made: Models of the teeth will be made.

You receive your trays and gel: You will be shown how and when to use the trays and bleaching gel. The number of weeks you will need to use the whitening gel depends on the discoloration of your teeth.

What happens during in-office tooth whitening (power whitening)? Your teeth are examined: Before you begin in-office whitening, your teeth must be clean. Any gum problems need to be treated. Any cavities must be filled, and old fillings may need to be replaced.

Your teeth are whitened: A rubber dam might be used to isolate the teeth, a whitening gel will be applied to the teeth, and a light may be used to accelerate the whitening process. The procedure will be repeated until the desired shade is reached.

• Brush and floss your teeth before inserting the whitening trays.
• Follow your dentist's directions exactly, and use only the materials your dentist gives you.
• Spit out any excess saliva. The gel won't harm you if swallowed, but it can irritate your throat.
• Don't eat or drink while you have the trays in your mouth.
• Rinse and brush your teeth after whitening.
• Avoid citrus fruits and other acidic foods, they can make your teeth more sensitive.
• Call your dentist if your throat, teeth, or gums feel irritated.