Dental MythBuster #2 – Diet Soda is Better for My Teeth?

Dental MythBuster #2 – Diet Soda is Better than Regular Soda for my Teeth.

Another common dental myth that I see nearly every day in practice in Orange, Connecticut is the notion that drinking diet soda is better for your teeth than non diet soda.  Frequently when I see a new patient with a lot of decay (a.k.a tooth cavities), both my dental hygienists and I discuss the dietary factors that influence decay.  While many people with cavities will admit to a sweet tooth or drinking lots of coffee with sugar, others will try to say “well I don’t understand why I have cavities because I only drink diet soda now.”  

The most accurate way to describe diet soda with respect to your oral health is as follows:

Diet soda is only marginally less destructive to your teeth than regular soda.  Frequent, daily consumption of either diet soda or regular soda will significantly increase the likelihood of dental cavities.

Soda vs. Regular Soda - both will cause tooth cavities for the dentist

In a previous blog post on Sports and Energy drinks, I wrote that dental decay was caused by sugary foods and acidic foods.  In the case of regular soda, you are ingesting sugar in an acidic liquid.  With diet sodas, there is no sugar, but the artificial sweetening is still being delivered in a very acidic mixture.  The acids in soda first weaken and then ultimately begin to wear away the tooth enamel.  Enamel is the hard outer layer of the tooth; without it, your teeth have little to no protection.

Differences between Diet Soda and Regular Soda on Teeth

As mentioned above, both acidic and sugary foods and drinks will cause dental decay.  We know that regular soda contains sugar.  I won’t bore you with the math, but on average, there are the equivalent of about 10 teaspoons of sugar in a typical 12 ounce can of soda.  Most sodas these days contain high fructose corn syrup but the distinction between high fructose corn syrup and sugar is not important for this blog post.  The key difference is that regular soda has large quantities of sugar while diet soda does not.  So when it comes to sugar content alone, diet soda is actually better for your teeth.

But what about acidity? There is lots of research on this topic.  In a widely cited 2007 study by the Academy of General Dentistry, the pH of Regular Coca Cola is 2.52.  Compare that to Diet Coke which has a pH of 3.28.  I won’t bore readers with chemistry here, but pH is a logarithmic measure of how acidic a liquid is.  A lower pH means greater acidity. Stomach acid has a pH of approximately 1.5 to 3.5.  Tap water has a pH of 7.  A key point to remember when you’re drinking diet soda then is:

Both diet and regular sodas are only slightly less acidic than stomach acid!

That’s very acidic!  If you’ve ever experience heartburn (GERD) you know the acidity of the stomach.  But what about the difference in acidity between Coke and Diet Coke? That can be best be summed up in the graph below:

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Graph showing the percent weight loss of tooth structure by type of Soda.  From the Academy of General Dentistry, March/April 2007

I included this graph from the same Academy of General Dentistry showing the percent weight loss of teeth immersed in different sodas for 48 hours.  A tooth immersed in Regular Coke for 48 hours would have 6% of its mass dissolved away, while that same tooth immersed in Diet Coke would lose “only” 1.5% of its mass.  Note that for 7 Up, the percent weight loss does not vary significantly between regular versus diet.

So what does this all mean? It is worth repeating what was stated in bold earlier in this post, which is:

Diet soda is only marginally less destructive to your teeth than regular soda.

Frequent consumption of diet soda will place you at increased risk for dental decay, resulting in the need for dental fillings. And if the decay is not treated in a timely fashion, you could end up needing crowns, root canals, or even having the tooth or teeth extracted, requiring dental implants!  Keep that in mind next time you reach for that Diet Coke or Diet Pepsi.

Thanks for reading, and stay tuned for the next Dental MythBuster in a couple of weeks.