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There is nothing fun about getting a cavity.  They can be uncomfortable to have and expensive to treat and sometimes it can feel like there's not much you can do to prevent them.  Like, you're already brushing your teeth twice a day and flossing, how did tooth decay happen?  In many ways, the world would be a better place if we could just prevent cavities from popping up altogether, and the beautiful thing is, we might be able to.  

Ultimately, to keep our mouths cavity-free, we have to tackle the main cause of tooth decay, and no, I'm not talking about sugar.  I'm talking about a bacterium called Streptococcus mutans.  It's one of the many types of bacteria in your mouth and it's one of the main things that causes cavities.  S. mutans lives on your teeth, feeds off the sugars on your tooth plaque and almost instantly turns those sugars into acid.  Normally, compounds in your saliva neutralize the extra acid after a few minutes, which is why you don't really notice S. mutans at work, but that acid can still accumulate around a microbe itself, and if you don't brush it away, you can develop a really acidic spot on your tooth.  If that spot develops for long enough, the acid can wear away the tooth's outer surface, potentially creating a pit so deep that it becomes a full-blown cavity.  That's a good reason to clean your teeth, but sometimes, cavities can happen despite your best efforts, and besides, not everyone has regular access to fancy toothbrushes and floss.

So while there are plenty of preventative options, scientists have also begun to investigate if there's anything we can do to get rid of S. mutans for good, and so far, they've found some possibilities.  For one, a few studies have noticed that people who have more of the amino acid arginine in their mouths tend to get fewer cavities.  According to a 2018 experiment, this could be because a different strain of Streptococcus metabolizes arginine into a tiny amount of hydrogen peroxide and that hydrogen peroxide prevents S. mutans from fermenting sugar and ultimately from growing, so if we could introduce the right kind of streptococcus into a toothpaste, we might be able to reduce cavities.  It isn't the only option, though.

In 2011, researchers also came up with a special mouthwash that can kill S. mutans while leaving helpful bacteria alone.  The compound in their mouthwash is called C16G2, which could probably benefit from a good brand name.  It's a synthetic antimicrobial compound designed to quickly target a specific chemical S. mutans gives off and while it can sometimes attack other bacteria, it almost only kills these cavity culprints.  In a test, the mouthwash effectively reduced the damage done to tooth enamel by the S. mutans bacteria as well, which is great.  

So far though, these options for eliminating cavities are promising but they're not well-tested enough to go primetime.  We'll need some more research to prove that they're definitely effective and safe, but hey, if this someday means a world with no cavities, I'm all for it.  This cavity problem is really just one big puzzle where scientists have to figure out how to get rid of S. mutans without disrupting the rest of our mouths. 

It's a huge exercise in problem solving and if that kind of thing sounds like your jam, you might enjoy the "Joy of Problem Solving" course on Brilliant.  The course doesn't focus on mouth bacteria.  Instead, it challenges you to improve your logic and math skills, but it does so in a really fun way that's way more interesting than your typical math lesson.  Like, you solve problems with humans and vampires, figure out how to rearrange coins, and learn more about how to catch when someone is stretching the truth, which, I don't know, seems like a pretty useful skill.  When you're done with this course, you can check out all of Brilliant's other math, science, computer science, and engineering courses.  They're working on some new courses, too, so keep an eye out for that.  If you want to sign up, head over to Brilliant.org/SciShow.  The first 200 people to sign up there will get 20% off their annual premium subscription.

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