Chewing on Your Oral Microbiome

Why some people always get cavities despite doing everything right

This is part two of our series on how Scout works. You can find part 1 here, and go check out Scout, which is on sale until January 1st, 2024!

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In part 1, we talked about how demineralization works. In that article, we briefly mentioned that bacteria can be partially responsible for our cavities.

Today, we’re going to get deeper into that and talk about the bacteria in your mouth, how they work, and why they explain why we all know one person who never gets a cavity despite poor habits, while another person can do everything under the sun and need a filling every visit. But to get to that, let’s talk about what our microbiome is.

Oral Microbiomes are a mix of microorganisms

Your oral microbiome is the unique mix of microorganisms in your mouth. It’s a collection of bacteria, protozoa, viruses, and even fungi that all coexist. Some parts of this collection have been with you consistently since childhood, while other microorganisms are more transient and rarer, unique to some people, some places, or some times of life. But, whether they’re persistent or transient, our oral microbes play a huge part in your overall health.

They really are all just happy to have a home

The 700+ species found in your mouth all have specific preferences about their living situation. Like a picky roommate, these species will isolate themselves as best they can to exist without competition. With all the nooks, crannies, and surfaces found across the mouth, different organisms can thrive in tons of unique regions. Your oral microbiome is described almost as much by microorganism positioning as by which types are in the mouth.

In some cases, microorganisms will even create their own areas of exclusion by manufacturing a biofilm to live under. Like a chemical tarp or tent, this biofilm gives the microbes increased shelter from the elements, including your toothpaste. As we'll see in a second, these biofilms play a huge part in your dental health.

Let’s meet the major players, good and bad

While there are over 700 microbes that make up your oral microbiome, a few play outsized roles in your oral health, particularly with cavities and gingivitis.

The Good:

1. Streptococcus salivarius: A family of a few different bacteria, these help suppress the bad bacteria and reduce their ability to colonize.
2. Ligilactobacillus salivarius: Similar to S. salivarius, L. salivarius is able to suppress bacteria that would otherwise cause cavities. In some cases, L. Salivarius can even help suppress inflammatory molecules.
3. Limosilactobacillus reuteri: A lactobacillus like L. salivarius, L. reuteri produces compounds that can help control other bacteria that cause cavities. Beyond that, L. reuteri produces Reuterin, which can kill Candida, the fungus responsible for thrush.

These three are just a small subset of a huge group of organisms that can be beneficial when found in the right spot. But, like E. Coli, they can cause problems if they end up in the wrong place at the wrong time.

The Bad:

Some microbes, though, are truly out to cause problems. Two in particular are responsible for a slew of oral problems.

1. Streptococcus mutans: S. mutans is the most well-known cavity-causing bacteria. S. mutans is purpose-built to attach to teeth efficiently and is able to produce robust biofilms that protect them while they produce loads of lactic acid that cause rapid demineralization.
2. Porphyromonas gingivalis: P. gingivalis is one of the big players in gingivitis and periodontitis. Able to escape immune response and secrete inflammatory enzymes, P. gingivalis is able to cause severe problems in the gums if allowed to flourish.

These bad actors and a mix of less well-known ones play an enormous role in our health. In fact, S. mutans and P. gingivalis have even been found in heart plaque, having spread there from the oral cavity.

Life didn’t give us lemons. We made our own

With S. mutans being so harmful, it begs the question of how it got there in the first place. One would assume that a bacteria that harmful would warrant an evolutionary response. The answer, unfortunately, is that S. mutans is Frankenstein’s Monster, a creature of our own creation.

The King of cavities has an unfortunate backstory.

When we were a fledgling species, we didn’t consume much sugar. That meant less carbs for the microbes in our mouth, which meant they were much more controlled. However, with the increase in sugar consumption, microbes could get more aggressive, so we found ourselves with a new species, S. mutans.

Those biofilms I mentioned are entirely a result of this evolution. S. mutans uses sucrose to make its biofilms. Sucrose, which, until the modern age, was fairly rare. This Sucrose-based film is potent, keeping out fluoride and beneficial bacteria and even letting S. mutans resist mechanical cleaning in some cases. The result of our sugary diets is a bacteria that is incredibly good at staying on our teeth and giving us cavities. The truth is that life didn’t create any lemons; we made our own.

Is Oral Health Genetic?

So, if so much of our oral health is due to the microbiome, is oral health genetic? It’s common for oral health to seem to be passed on, but can we really say it’s an actual genetic expression? The answer is complex.

If only it were an easy comparison between the two sides

When you come out of the womb, your oral microbiome is a nearly blank slate. An empty canvas ready to be painted by your encounters with the world. That said, you already have some genetic predispositions at play. Everything from the pH of your saliva and how much you produce to the shape and structure of your enamel is affected by genetic expression. Simply put, while you’re a blank canvas when you come out of the womb, that canvas already has a particular shape, priming it for a certain outcome.

Even beyond genetics, your heredity has an impact. The very first bacteria that you encounter are those shared with you by your parents. From the moment you’re born, bacteria start to jostle for a place in your mouth. Given how much time and exposure you have with your parents, its no wonder that their own oral microbiomes have a huge impact on yours.

While genetics can control some aspects of your oral health, you can’t rely on them to keep your mouth healthy, so let’s talk about how you can.

Improving your oral microbiome

Your hygiene habits are the most important factor in oral health. Whether you’re predisposed to cavities or not, leaving a big chunk of food stuck between your teeth because you don’t want to floss is a good way to end up with a cavity. An overly sugary diet can give the bad bacteria all the energy they need to thrive. Good hygiene habits are the best line of defense whether or not you were blessed with a better oral microbiome.

Fluoride also plays a large part in your oral microbiome. Fluoride can help to inhibit bacteria like S. mutans and P. gingivalis while disrupting biofilms and restoring the underlying enamel. While you may be unable to control their presence, regular brushing and dentist visits are the best ways to keep them in check.

And, of course, it always helps to have technology on your side. Scout’s wellness scoring system can help you track the markers of microbiome health and may help you avoid those painful cavities. Go ahead and check it out here!

Thus concludes the brief story of our microbiomes. Stay tuned for the next article, where we’ll dig deep into the science of Scout’s imaging system.

Disclaimer: Scout is a wellness device, not a medical device. It is intended only for general health and wellness purposes, and it has not been evaluated, assessed, or approved by the FDA.