Myths and Facts About Cavities

Medically Reviewed by Alfred D. Wyatt Jr., DMD on December 16, 2016
5 min read

We’ve heard about cavities since we were kids. Yet our understanding of what they are, how we get them, and what we can do about them is often somewhere back in the third grade.

If my teeth don’t hurt, they’re fine, right?

Not always.

“By the time something hurts, it’s gone way too far," says Matt Messina, DDS, a dentist in Fairview Park, OH. “By the time it hurts, then the nerve of the tooth is becoming annoyed and involved, so we’ve taken a simple filling and maybe taken it closer to a root canal or something like that.”

That’s why regular checkups are so important.

“I think we have pretty much discredited the notion that, ‘Wait till it hurts,’” says Andy Marashi, DDS, a Seattle dentist. “Decay does not necessarily hurt.”

You know what really hurts?

“The longer it goes,” Marashi says, “the more expensive it is.”

This is much trickier than it sounds. Yes, sugar can cause cavities. But it’s not sugar by itself. And it’s not just sugar, like the stuff in candy or what you use to sweeten your coffee.

The sugars in foods like bread, beans, fruit, potatoes -- and many others -- act with bacteria already in your mouth to form acids that can eat away at your teeth.

That’s why it’s so important to brush, floss, and rinse with antibacterial mouthwash. You should brush at least twice a day (for 2 minutes each time), floss at least once every day, and rinse once a day. If not, the formation of cavities starts. First, plaque forms on your teeth. Once it’s there a while, as you eat more things with carbs, the plaque turns to acid.

“And that acid, over time … it’ll wear a hole in your tooth,” says Kimberly Harms, DDS, a dentist from Farmington, MN. “Once that hole gets in the tooth, then that bacteria can get inside the little hole, and you can’t brush it or floss it away, anymore.”

When that happens, cavities aren’t far behind. So, yeah, that sugar-filled candy is no good for your teeth. But neither is that pasta if you don’t brush, floss, and rinse.

It’s not just sugar that can get at your teeth. Anything that makes your mouth more acidic can cause havoc.

That includes sodas, even diet ones.

“It’s better than having a sugary soda,” Hans Malmstrom, DDS, of the Eastman Institute for Oral Health in Rochester, NY, says of diet soft drinks. “But all sodas, more or less, have a low pH, and low pH causes erosion to your teeth.”

Once erosion starts, it’s not nearly as tough for cavities to form.

Experts say enamel on the surface of a tooth can get some of its minerals back. So you can slow decay down and maybe even stop it. But once bacteria and decay get through that enamel, the damage is done.

“Once that bacteria gets so far into the tooth that you can’t brush it away, it’s not going to get better, Harms says. “Cavities don’t go away once they start. You have to fix them.”

Messina says there’s a point of no return: Once the bacteria it goes halfway through the enamel.

Not necessarily.

“A lot of time what it is, that decay process started but then it stopped. [The enamel on the tooth] hardened up again,” Marashi says. “And a lot of times, when it hardens up, it has a discolored look to it. But it’s not necessarily a cavity.”

Once your tooth is invaded, if you don’t fix it, some hard times in the dentist chair await.

The decay will get into the nerve of the tooth. Eventually, that nerve will die. Then, the choices are a root canal, which removes the dead nerve, or removal of the tooth.

“If we don’t do anything, it’s not going to end up in a good place,” Messina says.

This old remedy may help. Some. But it’s probably not worth it.

“You’re going to burn the [gum] tissue. You may reduce the pain a little bit in the tooth itself, but it’s not going to help the tooth long term,” Malmstrom says.

If your tooth is sore, you probably have either a gum issue or a nerve problem inside the tooth.

So, Malmstrom says, burning the tissue can help a little. Still, the aspirin wasn’t meant for that. What’s more, if you do see a dentist, the acid from the aspirin may make it more difficult to numb the area that needs work.

They can last a long time. A decade or more. But “the tooth didn’t last a lifetime, so the filling won’t either,” Messina says. “God made [the tooth] and it still decayed. And I’m not on that level.”

“Not only can the filling wear and break down, but the tooth can still decay around the edges of the filling,” Messina says. “Nothing’s permanent. But the better care we take of our teeth, the longer we can make them last.”

With fluoridation of local water systems and overall better oral health, the mouths of Americans may be in their best shape ever. But adults still can get cavities.

Sugary drinks, poor oral hygiene, even genetics can lead to cavities at any age, experts say. Adults, too, take medicines that dry out mouths. This matters because your saliva helps buffer all the acids in your mouth.

Poor eating habits, like snacking all day and constantly sipping sodas, don’t help.

“Unfortunately, the risk for cavities exists from the time the first tooth erupts to the time the last tooth falls out,” says Maricelle Abayon, DDS, a dentist from Rochester, NY. “The key is to kind of be very vigilant. A cavity is not the end of the world. But having multiple cavities, at any age, can impair your quality of life.”