Tooth Bacteria

We have 700 different species of bacteria swarming in our mouths, but only one species causes most of our tooth decay. Another dozen harm us in other ways. The rest - 680 plus species - help keep us healthy.

Licking Tooth Decay

We nag our kids to brush their teeth well, but a few hours later, their mouths are just as full of bacteria as before they brushed..

Microbiologist Wenyuan Shi of UCLA thinks a sweet sucker might help lick the problem.

Shi laments that while the cause of tooth decay is known to be an infection, dentistry today still uses a “mechanical” approach to disease.

He says that there are 100 trillion bacteria in your mouth, consisting of 700 different species, but only 12 of those species cause any harm. One in particular, Streptococcus mutans, is a major factor in tooth decay.

“What we really try to do is to detect the pathogen who is responsible for the tooth decay, and treating the pathogen or get rid of the pathogen way before they [are] damaging the tooth,” says Shi.

The challenge of that approach is that some of those bugs are actually beneficial. So Shi is working on ways to target the harmful bacteria while leaving the beneficial ones alone. “It’s like a dandelion infection in your lawn,” he says, “and if you use a general herbicide, you do kill the dandelion, but you kill the grass as well; and the moment you stop using your herbicide, who comes back first? It’s always the weeds.”

Shi looked to his Chinese roots for a traditional herbal remedy that targets only the bad bacteria. “We did a lot of the screening, and to our great surprise, one of the top hit we got out of the 2,000 medicinal herbs is licorice. And, as you know, many cultures have been chewing the licorice roots as a way to actually promoting oral health,” he says.

As they reported in the Journal of Natural Products, Shi’s team isolated the active compounds in licorice and showed they kill decay-causing bacteria in lab tests. With corporate partner C3-Jian, Inc., they developed an extract that would specifically combat S. mutans.

To get the compounds into extended contact with teeth, they put them in a lollipop, manufactured and sold by Dr. John’s Candies, which specializes in sugar-free candy. The lollipops are orange flavored.

You can’t get the same effect from just eating licorice. Most licorice sold in the U.S. is actually flavored with anise. Plus it contains lots of sugar, which is bad for your teeth.

Real licorice falls under the “generally recognized as safe” category by the FDA so the lollipops are already on the market, and starting to show up in dentists’ offices and pharmacies.

Shi says parents like that kids like them. “There are some of those parents you know come to walk to me and saying oh, you know, how grateful they’re finding this technology helping, you know, their kids.”

Shi says the lollipops passed a series of safety tests and they are currently undergoing human trials to establish effectiveness in actual use.

In 2012, another group of researchers identified “isoflavinoids and coumarins” from ground licorice root that had anti-bacterial activity. I am not sure if it means anything, but some of the researchers involved in that study were from Tom’s of Maine.


Interviewee: Wenyuan Shi, UCLA
Length: 1 min 16 sec
Produced by Sandy Chase
Edited by Sandy Chase & James Eagan
Copyright © ScienCentral, Inc.

For more information on gut bacteria, here is a great blog.



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