Does Soda Actually Erode Teeth?

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Soda_bubbles_macro.jpgI recently received a mass email from a coworker that reported some scary facts about soft drinks. I instantly realized that one fact on the list was not correct. It said that the acid in Coca-Cola dissolves the rust off a nail, thereby implying that Coke harms your teeth. While it's true that Coke can de-rust a nail, this property of Coke is no indication of what Coke does to your teeth. Plenty of other beverages (like orange juice and energy drinks) are just as acidic as Coke, and would do the same thing to the nail.

Snob that I am, I quickly looked up the article where I'd learned this and sent it to my coworker. Soon after, I realized that I had no idea whether or not soda actually does dissolve teeth. Of course, I'd heard that pop isn't good for teeth (or any part of your body), but I didn't know exactly why.

It seems that soft drinks destroy your teeth by two different methods: decay and erosion. Tooth decay occurs when bacteria feed on the sugar left over on teeth. The bacteria's method of digestion, fermentation, releases lactic acid as a by-product, which then dissolves the calcium in your teeth. Because bacteria hang out in the nooks and crannies of your teeth, the acid is often concentrated to certain spots, causing cavities.

Erosion is tooth damage directly by acid without bacterial involvement. The main acids lurking in beverages are phosphoric acid and citric acid. Fizzy drinks also have carbonic acid that comes from dissociated carbon dioxide, but it is too weak to have any affect on teeth. Phosphoric and citric acid, on the other hand, cause damage by dissolving the calcium that comprises teeth.

Both types of tooth damage occur because teeth have a dynamic relationship with their environment (aka your mouth). The minerals found in teeth, like calcium, are constantly being dissolved and replaced. Usually this exchange is regulated by your saliva, which buffers the environment to make sure the amount taken away is equal to the amount added back. But when your drink soda, your mouth suddenly becomes more acidic. Your saliva can't keep up, and the amount of calcium dissolved is greater than the amount replaced.

The effects of pop on teeth sound pretty believable in theory, but do they translate into real life?

Many studies have been published about soft drinks' affects on teeth. If you ask me, some of these these studies are about as convincing as the rusty nail trick. For instance, one study published in May claimed to show that consumption of energy drinks and sports drinks causes tooth erosion. Basically, the researchers weighed some teeth, plopped them in the drinks for fifteen minutes sessions, and then re-weighed them. The American Beverage Association responded to this study in a strongly-worded press release, and I admit I have to agree with some of their points.

This study was not

conducted on humans and in no way mirrors reality.  The authors used

slices of tooth enamel samples from extracted molars, and then placed

them in petri dishes of liquid for extended periods of time.  People do

not keep any kind of

liquid in their mouths for 15 minute intervals over five day periods.

Thus, the findings of this paper simply cannot be applied to real life

situations.

Other, more convincing, in vitro studies look at microscopic damage on the surface of teeth when they are exposed to soft drinks.

However, the prevalence of soft drink consumption on tooth

erosion in large populations has not been extensively studied, especially in the United States. In 2001, the American Dental Association published a report which cited a couple studies showing a positive association between soft drink consumption and dental erosion. A more recent 2009 study found that 45.9% of U.S. youth aged 13-19 had at least one tooth with signs of erosion.

Interestingly, many more epidemiological studies about dental erosion have been conducted in Europe than in the U.S. These studies show a clear association between acidic soda and dental erosion in young people. One group of researchers suggest that the abundance of literature about tooth erosion in Europe is simply a reflection of more dental erosion in these countries. What's more, they posit that the drink recipe could play a role after observing that U.K. drinks are typically more acidic than their U.S. counterparts. Orange juice, for instance, is more acidic in the U.K.

In fact, soft drinks are not the only teeth-eroding beverage, and they are also not the worst. In one study, researchers measured the buffer capacity of several beverage types. Buffer capacity indicates how difficult it is for saliva to neutralize acid in the drinks. The study found that fruit juices and fruit-based carbonated beverages have a higher buffer capacity than non-fruit carbonated beverage and are therefore more likely to erode teeth.

More research is required to determine how many Americans are affected by dental erosion from acidic beverages, but it seems that there is a correlation supported by science. The good news is there are several things you can do to prevent tooth erosion. Of course, the most obvious option is to simply not drink these beverages. But, if you're like me and you enjoy a soda now and then, you might want to consider using a straw and refrain from brushing soon after.

(Photo via Wikimedia Commons)   

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