Why Teeth Turn Yellow (and other colors)

Causes of Tooth Discoloration and How To Fix It

Drinking coffee and tea can cause teeth to turn yellow, but there are many other reasons for tooth discoloration.
Drinking coffee and tea can cause teeth to turn yellow, but there are many other reasons for tooth discoloration. Tomas Rodriguez / Getty Images

You know teeth can turn yellow from staining due to coffee, tea, and tobacco, but may be unaware of all of the other causes of tooth discoloration. Sometimes the color is temporary, while other times there is a chemical change in the composition of teeth that causes permanent discoloration. Take a look at the causes of yellow, black, blue, and gray teeth, as well as how to avoid or correct the problem.

Reasons Why Teeth Turn Yellow

Yellow or brown is the most common tooth discoloration.

  • Any intensely-colored plant matter can stain teeth, as the pigment molecules bind to the surface layer of enamel. Chewing or smoking tobacco darkens and yellows teeth. Dark, acidic drinks like coffee, tea, and cola do a double-whammy as the acid makes teeth more porous, so they pick up the pigment more readily. Surface staining doesn't have to be yellow. Depending on the cause, it could be orange or even green. The good news about this type of stain is that it can be removed with good dental hygiene and a whitening toothpaste.
  • Mouthwash can stain your teeth. Products containing the antibacterial agents chlorhexidine or cetylpyridium chloride cause surface discoloration. The color is temporary and can be bleached away.
  • Medications may also yellow teeth. Antihistamines (e.g., Benadryl), drugs for high blood pressure, and antipsychotics typically cause surface discoloration, which may be temporary. The antibiotics tetracycline and doxycycline become calcified in developing enamel. While the antibiotics won't noticeably stain adult teeth, these drugs can cause permanent discoloration and sometimes disfigurement of teeth if the drugs are administered to children under age 10. Pregnant women are advised against taking these antibiotics because they affect fetal tooth development. It isn't just the color of the tooth that is affected. The chemical composition of teeth is altered, making them more fragile. Bleaching won't solve these problems, so the usual treatment involves crowns or replacing teeth with implants (in severe cases).
  • Yellowing is part of the natural aging process, as tooth enamel becomes thinner and the natural yellowish color of the underlying dentin layer becomes more visible. Thin tooth enamel also occurs in people who have a dry mouth (produce less saliva) or who routinely eat acidic foods.
  • Chemotherapy and radiation can change the color of enamel, giving it a brownish cast.
  • Sometimes a yellowish color is genetic. Inherited yellow enamel can usually be bleached to become brighter using over the counter whitening products.
  • Poor dental hygiene can cause yellowing, since plaque and tartar are yellowish. Brushing, flossing, and visiting the dentist are steps to address this issue.
  • Ingesting fluoride from fluoridated water or supplements usually causes splotches in developing teeth more than overall yellowing. Too much fluoride can also disfigure teeth, since the chemical structure of enamel is affected.
  • Dying teeth appear more yellow than young, healthy teeth. Physical trauma, poor nutrition, sleep deprivation, and stress can all affect the health of underlying dentin and make it appear darker and more yellow.

Causes of Blue, Black, and Gray Teeth

Yellow isn't the only type of tooth discoloration. Other colors include blue, black, and gray.

  • Dental amalgams made using mercury or sulfides can discolor teeth, potentially turning them gray or black.
  • A severely damaged or dead tooth may have black spots as the internal tissue dies, similar to the way a bruise appears dark under the skin. Trauma can affect tooth color in both adults and children. Because this discoloration is internal, it can't simply be bleached away.
  • There are two main causes of blue teeth. One is that a white tooth may appear blue if the tooth has a mercury-silver filling, which shows through the enamel. Damage to the root of a tooth may also show through as blue. The other main cause is when the root of a tooth fades away. This is more commonly seen in children losing their deciduous (baby) teeth, when their teeth are otherwise very white. Enamel is crystalline apatite, so either dark underlying material or a lack of any material may make it appear blue-white.