Composite (plastic) resins are matched to be the same color as your teeth and therefore used where a natural appearance is desired. The ingredients are mixed and placed directly into the cavity, where they harden. Composites may not be the ideal material for large fillings as they may chip or wear over time.
Your dentist will first photograph your teeth which will help to know the progress of the treatment. This is also used to examine your tooth and figure out the stains.
After examining the tooth dentist will start by cleaning the tooth. He will remove the film on your enamel coated due to the food you eat or due to other substances. The whitening process begins after this. The entire process takes around 30-90 mins depending upon the severity of the stains on teeth. Your dentist will cover the gums and will then apply the whitening agent on teeth. Some whitening agents require laser lights on them and if your teeth are badly stained then your dentist will suggest you continue the process at home for a few days.
You can also opt for home whitening treatment, in this, your dentist will take an impression of your teeth and will make a custom fit mouthpiece. This helps the whitening agent to stay intact on your teeth.
One can also buy over the counter whitening products which is suitable only for the teeth which are not heavily stained.