Oral pH: The Chemistry of Healthy Mouths

Most of us learn a little about the pH scale in our science classes as teenagers. What does that have to do with oral health, though? A lot, actually, which is why we’re going to take this opportunity to give our patients a quick refresher on the basics of pH.

The pH of Our Mouths

Different parts of us have different ideal pH levels. Healthy skin should be mildly acidic (around 5.5) while blood should be slightly basic (7.4). For healthy teeth and gums, our mouths should be as close to neutral as possible. Unhealthy mouths tend to be more acidic, which is very harmful to tooth enamel. Even though enamel is the hardest substance in the human body, it’s very vulnerable to acid erosion. It will begin to erode at a pH of just 5.5!

Saliva: Our Natural Defense Mechanism

So how do we fight back against all those acid attacks? First, we have the built-in defense of saliva. Saliva washes away food particles and neutralizes our oral pH. This essential job is why dry mouth can be so dangerous for oral health. Without saliva, our teeth are more vulnerable.

We should do as much as we can to help our saliva do its job. It’s a bad idea to sip on sugary/acidic drinks or eat a lot of snacks, because every time we eat, our saliva has to start neutralizing our oral pH all over again, and the acid has more time to erode our enamel. If you’re going to indulge in occasional treats, keep them to mealtimes.

Cut Down on Acidic Foods

Another way we can help our saliva protect our teeth is by cutting down on the acidic foods and drinks and trading them for more alkaline ones. That means eating more fruits and veggies and fewer breads, dairy products, and meats. We should especially minimize the amount of soda we drink and sugary treats we eat.

Video Transcript

Acids and bases are everywhere. They’re used to make foods, soaps and detergents, fertilizers, explosives, dyes, plastics, pesticides, even paper. Our stomachs are very acidic. Our blood is slightly basic. Our proteins are made up of amino acids, and the letters in our genetic code, those As, Ts, Cs, and Gs, are all bases. You were probably taught how acids and bases behave on the molecular level. You were probably never taught that a long time ago, like ancient Greek ago, before anyone knew about atoms or molecules, acids and bases were defined by how they behaved. Acids tasted sour and corroded metal. Bases felt slippery and could somehow counteract acids.

When molecules dissolved in water interact, they are exchanging two main currencies with their surroundings: protons, also known as hydrogen ions, and electrons. Depending on how a molecule is composed or shaped, it may be willing to donate or accept either protons or electrons with some other community member. And some molecules are far more aggressive than others when it comes to donating or accepting either currency.

Remember that protons are positively charged and electrons are negatively charged. So, if a molecule is willing to give up a proton, that’s not too different from it being willing to accept an electron — either way it’s becoming more negatively charged. Other molecules are willing to accept a proton or give up an electron. These are becoming more positively charged. Some substances are so aggressive about donating their protons that when they get a chance, all of the molecules in a sample will dump a proton, sometimes more than one, to the surrounding water molecules. We call these strong acids.

Meanwhile, some compounds are so ready to accept a proton that they won’t wait around, they’ll just rip one off water, which usually has two protons but is generous enough to hang out with just one. We call these strong bases. Other acids and bases are not so strong. They may donate just a few of their protons to water or accept just a few protons from water, but most of their molecules stay exactly the same. If left alone in water, they’ll reach some equilibrium point where maybe only one out of a hundred or one out of ten thousand of their molecules has exchanged currency with water. As you might guess, we label these acids and bases weak, but in the common sense of the word, they’re not weak. The vinegar in your salad dressing that you can smell from across the room, that is a weak acid. The ammonia you spray on glass for a streak-free shine, that is a weak base.

So, it doesn’t take much to be an active player in the chemical economy. Most acid-base chemistry takes place in water, which can act as either an acid or a base, accepting deposits and enabling withdrawals like a 24-hour molecular ATM. And when a proton-deposit customer, that’s an acid, and a proton-withdrawal customer, the base, shop at the same time, their net effect on water’s account may cancel out, and we call this neutralization.

Now, certain molecules can behave as acids or bases without water, but that’s another story. Let’s end by saluting water as the resilient and fair banker for acids and bases. It’s always open for business, doesn’t charge interest, and will never foreclose on your molecules, which is more than I can say for [bleep]. Waah-waah.

We’re All Part of the Fight Against Enamel Erosion!

Following all these tips doesn’t make it any less important to brush twice a day for two full minutes, floss daily, and keep up with your regular dental appointments! If you want to learn more about how to keep your tooth enamel strong, we’d love to answer your questions. We want all of our patients to have the tools to keep their teeth healthy for a lifetime!

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