SACRAMENTO, Calif., U.S. — Stained teeth are a common sight at the practice of the Sacramento Dentistry Group. Restoring these teeth requires cleaning by an expert dental hygienist or professional tooth whitening to remove stains entirely.
As with most problems, however, prevention is the best cure. Therefore, a patient recently asked this question: “Which stains my teeth more: coffee or diet cola?” To understand tooth staining, we first need to discuss why tooth enamel stains and what those stains come from.
What Stains Teeth?
Two substances are primarily responsible for tooth stains: natural and artificial pigments (think artificial food coloring) and tannins. Tannins are found in many forms of plant life and tend to combine with pigments. Pigments give things their color.
Although enamel seems really smooth when the teeth are clean, at the microscopic level there are bumps, ridges, and depressions on the surface that collect and trap both pigments and tannins. Stains are created when pigments get stuck in one of these surface irregularities. Tannins create stains by first getting stuck on the enamel and then attaching to pigments that slide by. Pigments on their own are bad enough for stains, but add in tannins and the amount of staining increases.
The Acid Factor
An additional factor in tooth stains and the important difference between coffee and cola is acid. Highly acidic liquids soften the enamel, making it easier for both pigments and tannins to stick to it.
Coffee is only mildly acidic (typically between 4.5 and 6 on the pH scale, with a pH of 7 representing plain water).
In contrast, colas are very acidic, ranging from the 2.7 to 3 on the pH scale. Therefore, cola softens up the enamel and provides the pigments to stain it.
For a dentist, the greater concern with these two drinks is the high acidity of colas. Coffee definitely stains teeth, but cola both stains and damages them. A dull tooth can still be perfectly healthy, and removing stains is rather simple. Repairing teeth damaged by acid is far more difficult.
So if you ask a dentist to choose between regular coffee and diet cola, the answer will probably be in favor of coffee.
Of course, those dental surveys always seem to result in responses like “4 out of 5 dentists prefer…”, so it may be impossible to speak unanimously.