The Theme of Health in Acids and Bases
Soft Drinks and Tooth Decay
Soft drinks may taste sweet and refreshing, but consuming too much of the stuff can be detrimental to our health in all sorts of ways. Much research has focused on the excessive sugar content of soda, but more recently scientists have been testing the effects of the low pH of most sodas on tooth decay.
Believe it or not, the pH of soda is nearly as acidic as battery acid. RC Cola, for example has a pH of ~2.4. Chemicals such as phosphoric acid and carbonic acid in soda contribute to the acidity. Researchers have found that when teeth are placed in soda, very rapid decaying of the enamel of the tooth can be observed. The results suggest that drinking soda (or pop in some areas) routinely and excessively can result in some pretty nasty tooth decay.
While your body probably isn't thrilled to deal with copious amounts of acid in the form of coca cola everyday, your mouth does have clever tricks to help balance the pH of drinks before they make their way down to the stomach. Turns out that saliva has some buffering properties. When an acid like soda gets swished around a bit in your mouth, conjugate bases in the saliva can absorb some of the excess H+ atoms. This results in some neutralization.
However, dentists do not recommend swishing soda around in your mouth because that increases the exposure time to your teeth. In fact, based on the tooth decay studies, some dentists recommend drinking soda with a straw to help minimize exposure to your teeth. It's a lose-lose situation since the pH of the stuff making it to your stomach remains very acidic. Think about that next time you're at the soda machine.