What causes discolored teeth and is there any way to cure or prevent staining?

Ronald Perry, clinical professor and director of the Gavel Center for Restorative Dental Research at Tufts School of Dental Medicine, responds

There are many circumstances that can cause discolored teeth. Most of the time, the stains are “extrinsic,” affecting the tooth enamel alone, and can be corrected.

An example of extrinsic discoloration is stains caused by foods or beverages. Black tea or coffee; wines, both red and white; and darkly colored foods such as beets or chocolate are prime culprits. Other foods likely to stain teeth are berries, popsicles, candies and pickles.

Soy sauce, curries and tomato sauce can cause teeth to yellow over time, and smoking and other tobacco can stain teeth as well. In addition, creating an acidic environment in the mouth, whether through eating acidic food or by not brushing and flossing regularly, can make the enamel more vulnerable to staining. 

The best way to avoid extrinsic stains is to brush your teeth right after eating foods that can cause discoloration, and to make sure you’re brushing your teeth at least twice a day and flossing. Also, consume tooth-staining foods and beverages in moderation. 

When you do consume such foods and beverages, you can mitigate their effects in several ways. Drink tea or coffee with a little milk. Or drink iced tea or iced coffee through a straw. The same goes for fruit juices, sports drinks, and soda and other carbonated beverages—use a straw whenever possible.

And chewing sugarless gum can help neutralize the acids in the mouth. High-fiber foods can help lower the acid level as well; foods such as beans or spinach and other leafy greens help generate more saliva in the mouth and can “scrub” the teeth clean.

If extrinsic staining has already occurred, you can use at-home whitening systems or have your teeth professionally bleached. One home remedy is brushing teeth occasionally with a slurry of baking soda, but this is not advised for everyday use, as it can be very abrasive. Some home remedies for teeth whitening use hydrogen peroxide, and these remedies also must be used in moderation, since peroxide is extremely acidic and can corrode teeth.

Unfortunately, some types of discoloration cannot be easily erased. The discoloration may be “intrinsic”—that is, embedded in the tooth, having been formed in utero or as the teeth developed during childhood. This can result from use of certain antibiotics and other medications, or from trauma to a child’s tooth, such as a fall or a sports injury. Teeth with intrinsic damage often appear grayish.

Discoloration can also occur if the outer layer of enamel has worn away—for instance, through excessive tooth grinding. Then the teeth may appear to be yellowing, as the undersurface of the tooth is more yellow. To ameliorate the effects of tooth grinding, nighttime appliances can be used, and composite fillings or crowns may be used to repair damage and restore appearance. If too much damage has been done from grinding, restorative treatment may be necessary.

Finally, a calcium deficiency can cause discoloration, and large doses of fluoride can lead to white spots on teeth, a condition known as fluorosis that particularly affects children under 6. Drinking water supplies in some parts of the country naturally contain significant amounts of fluoride. Very low amounts of fluoride are added to many other water systems as a public health measure to help control tooth decay, especially in children. If your water system is fluoridated, you and your children may not need to use fluoride rinses—ask your dentist about this.

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