A carb-heavy diet and poor oral hygiene can leave children with early childhood caries (ECC), a severe form of dental decay that can have a lasting impact on oral and overall health.
A few years ago, scientists from Penn Dental Medicine found that the dental plaque that gives rise to ECC is composed of both a bacterial species, Streptococcus mutans, and a fungus, Candida albicans. The two form a sticky biofilm that becomes extremely difficult to displace from the tooth surface.
Now, a new study from the group offers a strategy for disrupting this biofilm by targeting the yeast-bacterial interactions.
“This offers us another tool for disrupting this virulent biofilm,” says Geelsu Hwang, assistant professor at Penn Dental Medicine and senior author on the study, published in mBio.
The work builds off earlier findings by Hwang that showed molecules called mannans on the Candida cell wall bound tightly to an enzyme secreted by S. mutans, glycosyltransferases (Gftb). In addition to facilitating the cross-kingdom binding, Gftb also contributes to the stubbornness of dental biofilms by manufacturing glue-like polymers (glucans) in the presence of sugars.
While some cases of ECC are treated with antimicrobial agents that kill the microbes directly, this doesn’t always break down the biofilm and can have off-target effects on “good” microbes as well as the oral cavity soft tissues.
Hwang and colleagues wanted to try a different approach that involved the yeast-bacteria interaction and opted to target the mannans in the Candida cell surface.
They applied three different mannan-degrading enzymes to a biofilm growing on a tooth-like surface in a human saliva medium, leaving it for five minutes. Following the treatment, the overall biofilm volume and thickness were reduced along with the bacteria-yeast interactions.
“The biofilm structure was more fragile after the enzyme treatment,” Hwang says. “We were able to see that the biofilms were more easily removed.”
The researchers kept the application time relatively short at five minutes though they hope to see activity in the two minutes recommended for tooth brushing. Hwang says a non-alcohol-based mouthwash with these enzymes added could potentially be used as a preventive measure against ECC.
The researchers hope to pursue this possibility with additional follow up, including testing these enzymes in an animal model. With more successes, they aim to add another tool for fighting the public health threat of ECC.