There are many ways to whiten your teeth. You can visit a dentist and they can whiten your teeth in the office or you can save money and whiten them at home.
When you whiten your teeth in the dentist office they will apply a block out dam on to your gums and apply 44% or higher whitening gel to your teeth. Then they will use a UV light that accelerates the whitening process. It normally takes about an hour and you will see immediate change in your tooth shade. The issue is that this normally only last a few months and your teeth will start to darken again.
I prefer the whiten at home method. The best way to whiten your teeth is to have custom whitening trays made. These are made just for you and your mouth, preventing the whitening gel from going everywhere. The advantage is that the trays will last forever; you just need to get extra whitening gel when you need a touch up. You can also purchase 35% gel for a low price. This is a lot easier that having to make another appointment with your dentist and spending a lot more money. I recommend the custom whitening tray made in a dental lab, but there are also thermo-form trays that you can make at home using boiling water. These work but are less comfortable and you end up using a lot more whitening gel because the gel goes all over.
If you are looking to whiten, I recommend spending a little money and get custom made whitening trays that will last for years. www.SportingSmiles.com