Preventing cavities may soon be as simple as popping a pill

Harmful bacteria can be powerful and hard to combat, but researchers at the University of Florida have found a way to fight fire with fire. 

A new study has discovered a superhero strain of oral bacteria that can subdue bad caries-causing bacteria in the mouth. The identification of this strain, a previously unidentified type of Streptococcus called A12, could open the door for the development of a supplement or probiotic that could be taken orally to stave off cavities.

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Since cavities often form when the pH levels in the mouth become acidic, maintaining a neutral pH can be key to dental health. Previous research discovered that ammonia assists with maintaining this healthy pH level, as it helps neutralize acid in the mouth. To create the ammonia, bacteria breaks down two compounds in the mouth, urea and arginine. Patients with an increased ability to break down these compounds were found to have fewer or no cavities.

As such, researchers wanted to identify which bacteria was the most effective at breaking down urea and arginine. To do this, study co-author Marcelle Nascimento, DDS, Ph.D., and her team collected plaque samples and isolated over 2,000 types of bacteria.  Of the 2,000 kinds, the team identified 54 bacteria that metabolized arginine.  Out of these 54, A12 was determined to be the most promising for a probiotic application.

“Like a probiotic approach to the gut to promote health, what if a probiotic formulation could be developed from natural beneficial bacteria from humans who had a very high capacity to break down arginine?" posited study co-author Robert Burne, Ph.D. “…the idea is that you could prevent a decline in oral health by populating the patient with natural beneficial organisms.”

Surprisingly, researchers discovered that in addition to metabolizing arginine in the mouth, A12 also kills Streptococcus mutans, particularly nasty bacteria that raises pH levels in the mouth and leads to caries development.

“[A12] effectively inhibited growth and two intercellular signaling pathways of the dental caries pathogen Streptococcus mutans,” the study reported. “A12-like organisms may play crucial roles in promotion of stable, health-associated oral biofilm communities by moderating plaque pH and interfering with the growth and virulence of caries pathogens.”

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“If you grow them [A12 and Streptococcus mutans] together, Streptococcus mutans does not grow very well or make biofilms, also known as dental plaque, properly,” explained Burne.

In addition to exploring the promising future of A12 as a probiotic supplement, Burne and Nascimento plan to explore using A12 levels as a risk assessment tool. “If we get to the point where we can confirm that people who have more of this healthy type of bacteria in the mouth are at lower risk of cavities, compared to those who don’t carry the beneficial bacteria and may be at high risk, this could be one of the factors that you measure for cavities risk,” said Nascimento. Patients with low levels could then receive supplements to raise their A12 levels.

The study, “Characterization of a highly arginolytic Streptococcus species that potently antagonizes Streptococcus mutans,” was published in Applied and Environmental Microbiology.