As we get older our teeth get darker. This is partly due to our getting older, but it is also caused by the foods we eat and drink, and by other habits such as smoking. Tea, coffee, blackcurrant juice, red wine and other foods that have strong colours can have an effect on the overall colour of our teeth. Teeth may also darken as a result of some antibiotics.
Some people naturally have a more grey shade of teeth. Other people have white spots on their teeth. This can be caused by early tooth decay, or illness when the tooth was forming.
There are a number of reasons why you might get your teeth whitened. Everyone is different; and just as our hair and skin colour vary, so do our teeth. Very few people have brilliant-white teeth.