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:

Alt Text

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.

Comments

  1. Great post. I had always thought that I didn’t have to worry about diet soda and my teeth. Now I know.

  2. Hello there! This post couldn’t be written much better! Reading through this article reminds me of my previous roommate! He continually kept preaching about this. I’ll forward this post to him.
    Fairly certain he will have a very good read. Many thanks for sharing!

    • Well it could have been written a little better. In the excerpt below, the second instance of “regular” should have been “diet.”

      “The key difference is that regular soda has large quantities of sugar while *regular* soda does not. So when it comes to sugar content alone, diet soda is actually better for your teeth.”

  3. Great post, very informative! As a drinker of coke zero, I am happy to learn that it doesn’t cause sugar damage to my teeth and it is less acidic than regular coke. So diet soda is clearly the healthier option for teeth (although water is still the best beverage).

  4. Thank you for this important and practical article.

  5. Robert Paul Hingston says:

    Tooth cavities only came about with the introduction of sugar, so something without sugar is less armful on the teeth. I’m not saying Diet Coke good as it’s high in Acid but there’s a lot of things that is high in acid. The main thing is to give up sugar to not have cavities, sugar is the culprit, The evidence for this is overwhelming

    • Sugar is definitely the major culprit. In fact, sucrose is directly responsible for a lot of it. After sucrose began being imported into the West Indies, dental caries in the area sky rocketed. A similar trend has been seen in every country where sucrose is suddenly introduced. The microbiology is well-known: a bacteria uses sucrose to build a glue that it uses to stick to the teeth and break down the enamel.

  6. I drink about 4 cans of Diet Coke a day. It’s definitely affected my teeth. As an addict, I’m not going to quit. So, what can I do to hold onto my enamel? Do fluoride rinses make a difference? Thanks.

    • Jamie,
      Anything with fluoride in it will help – but not completely stop – the erosion process. I would caution you against brushing your teeth RIGHT after drinking the diet soda. At that point, the enamel is weaker, and the mechanical action of the toothbrush will accelerate the loss of the enamel. You can try over the counter fluoride rinses. Or your dentist could give you a prescription for a high fluoride toothpaste.

  7. Thank you so much thi will really help me omn my science fair project. 🙂

  8. Where’s the control group in this experiment? How much mass does a tooth lose when immersed in regular drinking water for the same amount of time?

    • Adam,
      Thanks for the thoughtful response. I can’t locate the article online since the archives only go back to 2010 and I can’t find my hard copy. I will say this is a peer-reviewed paper so I suspect there was a control group. In general, as you look at the data, the less acidic a beverage is, the less mass the teeth lost. I know this doesn’t answer your question but it is the best I can come up with.

  9. Jakub Mares says:

    Hi guys,
    actually here’s scientifical study http://www.ncbi.nlm.nih.gov/pubmed/18071957 which says that mouth pH restores significantly faster after consumption of Coke Light. You have noted that Coke Light ph is 3.28 which fits to regular carbonated wated water: pH 3-4. All the soda waters are diluted carbonic acids which disintegrates quite quickly in higher temperatures therefore this quick mouth pH rebuild.
    When I look at the study it seems that most acidity in Coke light comes from carbonic acid (quick disintegration, fast pH rebuild) but regular Coke has some other (or more) acid aded + in long term supports acid producing bacteria growth.
    So conclusion is: Coke Light is significantly less harmfull than regular Coke. But on other side, if you need to drink it, drink a lot of it (no sipping trough the day, but larger portion at once) as good hydration raises salivation which helps to keep mouth pH. 🙂 (of course if you don’t mind color change of your teeth due brown colorants: )

    • Jakub,
      Thanks for the comment and link. I would not say that Coke Light is significantly less harmful than regular Coke. A better way of stating it is that they are both bad for your teeth, but regular Coke is worse. Kinda like saying that being put to death by lethal injection is much better than a firing squad… in my mind, neither option is good!

      • Not only is there no sugar, but it’s 5.7 times less acidic. And from the study in the comment above orange juice is worse for your teeth than diet soda. I think that qualifies diet soda as significantly better.

        Also, I’m not sure I believe the results of your graph. You’re noting that sugar and acid are the main culprits for the lost of mass of the teeth. Yet diet 7UP has a pH of 3.7 which compensating for the logarithmic scale of pH is 2.5 less acidic than the diet coke with a pH of 3.28. Why is the tooth breaking down more in a soda that is significantly less acidic? That combined with the lack of an evident control group makes this feel sketchy. I feel like the accuracy and precision of the study are both in question. I’d like to see a 3rd party lab achieve the same results.

        • 2.5 times* less acidic

        • Neil,

          Thanks for the comments.

          I could have written a blog post that went deep into the chemistry of this… where I explained the logarithmic nature of the pH scale… and how buffers work… and lots of other details.

          If I had, you likely never would have come across this article (nor would the thousands of other readers) as Google knows what types of articles people will likely read… and thus displays them more prominently in the search results. A chemistry laden one with lots of details would likely never see the light of day.

          As a result, are there simplifications in this post? Of course! Are there false statements? Of course not!

          As a dentist, I can’t tell you how many times I’ve had patients look at me when I tell them they have decay and they claim… “but I switched from Coke to Diet Coke three years ago. I can’t have cavities.” That is the essence of the myth… that if you drink diet soday it must somehow be good for your teeth.

          If you would like to consider diet soda as “significantly better” then you are more than welcome to. To me, that’s akin to saying that dying by lethal injection is better than dying by hanging. It’s technically a true statement, but both outcomes kinda stink don’t they?

          And remember, the pH of nearly all diet sodas are below 5.5, the pH at which enamel will demineralize.

          While I can’t speak for the study authors directly, the Journal is peer reviewed and well respected.

          • I don’t know if I would compare it to lethal injection and hanging. I think I would compare it to UV rays. The diet sodas are the low angle UV rays that travel through 5 times more ozone and the sugar sodas are like high angle UV rays that do significantly more damage at a significantly faster rate. Sure it’s better to cover up and never get any sun, but that’s not living. So you protect yourself from the worse of it the high angle rays.

            Whether it’s teeth or DNA, over time the wear and tear adds up. With teeth you get cavities or further compromised teeth, with DNA you get cancer. If you live long enough both are inevitable no matter how safe you play it. The rate of damage is 5.7 times slower for diet coke compared to coke. So protect yourself from the worse of it by avoiding sugar sodas.

            I drink a liter or so of diet soda everyday and I’ve never had a cavity. Maybe my genetics (combined with good diet, dental hygiene, and regular cleanings) have helped me get lucky. After all there’s plenty of smokers who haven’t got cancer yet. But I’d wager that if I’d been drinking sugar sodas all these years I’d not only have cavities, I’d have diabetes!

          • Neil,

            There appears to be a lot of semantics going on here. Regular, sugary soda will destroy teeth more rapidly than diet soda. Smoking 20 cigarettes a day is a lot worse than smoking 5 per day. So, does that mean smoking 5 a day is safe? No. That is the point of this post.

            If I had a dime for every time someone told me a story of someone they knew who drank lots of soda but never had a cavity… or someone who smoked for years and lived to be ninety… or someone who wasn’t wearing a seat belt and was in a horrific car crash but walked away unscratched… I would likely have several hundred dollars. Attempting to generalize based on the experience of one person is not how scientific studies are done. Try submitting a study where N = 1 and see how far that takes you.

            Regardless, I applaud your hygiene efforts for preventing you from developing decay. That’s great.

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  1. […] that was poorly made will collect even more food. If you combine this with a diet rich in sugar or acid, along with home hygiene that is not ideal, you have a perfect storm. That perfect storm affected […]

  2. […] 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 […]

  3. […] A) Taking in a huge amount of acidic or alkaline foods (Some people drink several liters of soda per day and have no problem despite soda having a pH of between 2.52 and 3.28) […]

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