The “perfect storm” lets certain bacteria seize the opportunity and take over the flora in our mouths. As you may recall from “Are You Ready for an Adventure?”, not all bacteria are harmful. The goal of oral health is not to sterilize the mouth (we never will)—it is to reach the right ecological balance. So how do we encourage beneficial bacteria and suppress harmful ones? Read on.
The sweet snack… what happens when we eat candy?
When we eat or drink anything containing sugar or carbohydrate, oral pH drops immediately from about 7 to around 5.5–5. In some people acidity goes even lower. The drop lasts from 30 minutes to two hours. Remember the graph from the Orbit ads? That is it.
A quick pH reminder
pH measures how acidic or basic a fluid is, from 1 (most acidic) to 14 (most basic). Pure water is neutral at 7. Below that is acidic; above is basic. When salivary pH falls from 7 to 6, it is actually ten times more acidic.
Tooth mineral dissolution begins around pH 5.5.
Back to sweets
A pH of 5–5.5 is acidic, but by itself it does not destroy enamel instantly. It does dissolve minerals—yet our remarkable saliva can neutralize the acidic environment within 30–120 minutes after the candy. Saliva is what brings acidity back toward normal.
Most bacteria dislike the sudden acidity after eating; they struggle to function and their metabolism slows. But the caries bacterium Strep. mutans, as we learned in the previous article, thrives in that acidity.
What next? Repeated sugar exposure drops pH, caries bacteria flourish, and they take over certain areas of the teeth. Is that how we “conduct the symphony in our mouths”? Certainly not.
Saliva to the rescue
Saliva constantly saves us from the low pH that follows eating. In fact it prevents caries in more than one way:
One mechanism is acid regulation that behaves like a relay race. One system raises pH to a point and passes the baton to another, and so on. Part of the buffering uses minerals; part relies on salivary proteins. Together they neutralize acidity as quickly as possible so pH favors remineralization rather than demineralization.
A second mechanism is rinsing—“oral clearance.” Saliva washes food debris, acids, and some bacteria out of the mouth. You may not love hearing this, but that is how we swallow many of our oral bacteria every day.
We produce nearly a liter of saliva a day, which shows that oral clearance is constant—usually without our noticing. It is an excellent way saliva stops processes that damage teeth.
How do sweet tastes affect saliva production?
If saliva helps both with acid buffering and oral clearance, how do we increase production? Here is the key.
The body makes saliva based on stimulation—first from chewing (one reason sugar-free gum, especially xylitol gum, is recommended after meals), and second, unconsciously, from taste. A study compared which taste elicited the most saliva—salty, sweet, or sour.
You guessed it: sweet taste causes the least saliva.
It makes sense that sour foods make our lips pucker and also stimulate far more saliva than sweets: sour foods contain acid, so the body is wired to buffer that acid with saliva. After sweets—especially when the habit is routine—saliva production often is not efficient enough to stop the damage.
So how do we stop the damage? Practical solutions
Here are simple ways to keep acids from destroying your teeth—besides cutting candy, of course:
- Rinse with water. A vigorous water rinse after eating boosts clearance, similar to saliva’s action.
- Even better—sip, swish, swallow, and repeat. Repeated rinsing with lukewarm water helps normalize oral pH because water is neutral. That leaves less time for mutans to dominate your flora. Swish forcefully to dislodge as much plaque as possible between teeth so it does not grow more acidic over time.
- Train your saliva. Yes—you can stimulate saliva and practice that capacity, especially if you take medications that reduce salivary flow.
- Wait—do not brush immediately after eating. Eating creates acidity, and acidity softens the surface minerals so enamel is more vulnerable at first. Give your mouth time to buffer before you brush, or you may scrub away a layer of softened enamel.
- Drink plenty of water. Hydration supports saliva production.
- Chew sugar-free gum. Chewing increases saliva flow.
Now that we understand this, we can discuss ways to encourage remineralization and rebuild our teeth. We hope these insights help you on the path to a cavity-free life.