Using Enzymes to Disrupt Childhood Caries

Improving the oral health of children with early childhood caries (ECC) is a priority for dental professionals, as the disease has long-lasting effects and may require surgical procedures to treat. Unfortunately, ECC often reoccur — even after preventive and surgical therapy.

A new enzyme treatment developed by researchers at University of Pennsylvania’s (Penn) School of Dental Medicine may help keep ECC at bay. This approach uses an enzyme treatment that intervenes with the synergistic interaction between the yeast and bacteria that cause ECC, while not harming surrounding tissues.

The team led by Geelsu Hwang, PhD, an assistant professor in the Department of Preventive and Restorative Sciences at Penn Dental Medicine, attempted to strategically develop a targeted measure to effectively prevent cross-kingdom interactions (Candida albicans and Streptococcus mutans) and subsequent biofilm development. “Symbiotic and synergistic interactions between these two kingdoms reinforce biofilm pathogenesis and the virulence of ECC,” he explains. 

“We found that our enzymatic approach significantly diminished the cross-kingdom biofilm development and its virulence by reducing total biofilm biomass, undermining the mechanical stability of biofilms, alleviating the acidic environment induced by the cross-kingdom biofilms, and reducing demineralization of the tooth surface,” Hwang says.

The team’s work builds off their 2017 paper that discovered molecules on the Candida cell wall, mannans, bound tightly to the enzyme secreted by S. mutans, GftB (glycosyltransferases). GftB manufacturers glucans in the presence of sugars, creating a gluelike effect that makes biofilm difficult to remove. To disrupt these interactions, researchers focused on three mannan-degrading enzymes (MDEs) — endoenzyme 1,4-β-mannanase and exoenzymes α- and β-mannosidase.

Researchers hypothesized that MDEs can disrupt S. mutans–C. albicans interactions by reducing the number of binding sites on the surface of C. albicans, thereby hindering the formation of mature cross-kingdom biofilm.

Each of the three MDEs were applied to biofilm growing on human tooth enamel blocks in saliva and left for five minutes at 37C. After the enzyme treatment, researchers report a reduction in overall biofilm volume, biofilm thickness, and interactions between S. mutans and C. albicans. When treated with a device mimicking mouth rinsing, biofilms were more easily removed. 

These enzymes were also determined not to harm human gingival cells in culture. The enzyme treatment would neither cause antimicrobial resistance nor disrupt homeostasis microbiota as it does not kill bacteria or yeast. Hwang explains, “Unlike conventional antibiotics, our enzymatic approach neither kills microbial cells nor harms gingival tissue; rather, it specifically targets the binding mechanism between S. mutans and C. albicans, which is one of the key virulence factors in ECC.”

The MDEs could potentially be an ingredient in an over-the-counter toothpaste or mouthrinse due to their ability to remain relatively stable under various surrounding environments, including human saliva of buffer solutions under various pH. 

The researchers hope this could be another tool for fighting early childhood caries. They intend to look further look into the efficacy via in vivo studies.

The study, “Intervening in Symbiotic Cross-Kingdom Biofilm Interactions: a Binding Mechanism-Based Nonmicrobicidal Approach,” appeared in mBio.