Teeth may turn dark for a number of reasons, including:
- not brushing and flossing regularly
- using the antibiotic tetracycline before age 8
- drinking a lot of coffee, tea, red wine, or other discoloring beverages
- living in a community where the water supply contains very high amounts of fluoride
- being born with certain genetic defects that darken tooth enamel
- having fever or certain other conditions at a very young age.