First we are going to look at the culprits that cause teeth to change color over time. If you know what is causing your teeth to darken or yellow, then you can start there.
One of the most common culprits of teeth discoloration is beverages. Teeth can absorb liquids you drink such as cola, tea, coffee, and red wine. Smoking and diet can also cause teeth to yellow. As you age the enamel on your teeth will begin to thin, causing the dentin on the inside to show through more, which makes the teeth appear darker in color.
At-home teeth whiteners can and do work to lift a couple of shades off of teeth.
Hydrogen Peroxide
The key ingredient in a lot of at-home teeth whiteners is usually hydrogen peroxide. Peroxide works by forming bubbles that remove stains from enamel. Peroxide is cheap and safe to use on teeth. To whiten teeth with peroxide you can swish and gargle a mouthful after regular brushing. You could also take a cotton ball or Q-tip dipped in peroxide and manually apply it to the teeth. Wait 2 minutes and rinse thoroughly. Never swallow peroxide. You may feel some burning at the gums and between teeth due to the bleaching agent becoming trapped, this is why you should rinse as thoroughly as possible.
Baking Soda
Using baking soda for whitening teeth has been around for decades. Baking soda has been deemed safe for use with teeth, and has been proven to work to whiten teeth. Baking soda can be used alone by dipping your toothbrush in it, or it can be mixed with your toothpaste. You can also mix baking soda with peroxide into a paste for extra whitening powder. If you mix with peroxide, use no more than two minutes and be sure to rinse thoroughly.
Strawberries
Not only is the fruit delicious, it can help whiten your teeth. Strawberries contain natural chemical ingredients that whiten teeth. You can slice a strawberry and rub it directly onto your teeth, or mash one up and use it as a toothpaste. Be sure to brush with regular toothpaste immediately after using strawberries on the teeth, and to rinse well.
You should brush your teeth regularly to try and prevent stains from forming. If you have lifestyle choices that contribute to the stains, you can change those as well. Lifestyle choices include smoking and drinking coffee.
There are also options on the market to whiten teeth such as teeth whitening strips and trays that can be purchased at drug stores. These have proven to work in whitening teeth.
Keep in mind that with any method you choose, it can take up to a few weeks to start visibly seeing results. Stains come off of teeth slowly, but they can come off with determination and dedication.