Deciduous (baby) teeth are typically whiter than the adult teeth that appear later. As we age, our adult teeth often become darker, yellower, or stained. This is partly why white teeth make people appear more youthful.
Just as there are a number of ways to lighten or brighten teeth, there are also several different ways for teeth to become discolored. The main causes of darkened teeth are genetics, antibiotics, and certain foods, plus teeth tend to darken as we age. Internal tooth discoloration is caused by changes in the enamel of the tooth and the dentin. The main causes of internal tooth discoloration are exposed to high levels of fluoride, tetracycline, use of antibiotics as a child, developmental disorders, tooth decay, restorations, root canal issues, and trauma.
External tooth discoloration is caused by factors outside the body, mainly foods and tobacco. The main causes of external tooth yellowing are smoking, foods with tannins, coffee, tea, carrots, oranges, and other foods.