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New dental material resists plaque and kills microbes

Biofilms composed of Streptococcus mutans—a common cause of tooth decay—were much easier to remove when grown on a newly developed dental material (right image), which has an antimicrobial agent within it, compared to a control material. (Image: University of Pennsylvania)
Dental Tribune International

Dental Tribune International

Tue. 19. December 2017


PHILADELPHIA, U.S.: Dentists rely on composite materials to perform restorative procedures, such as filling cavities. However, these materials, just like tooth enamel, can be vulnerable to the growth of plaque. In a recent study, researchers from the University of Pennsylvania evaluated a new dental material tethered with an antimicrobial compound that not only kills bacteria, but can also resist biofilm growth.

In addition, unlike some drug-infused materials, it is effective with minimal toxicity to the surrounding tissue, as it contains a low dose of an antimicrobial agent that kills only the bacteria that come in contact with it.

"Dental biomaterials such as these need to achieve two goals: first, they should kill pathogenic microbes effectively, and, second, they need to withstand severe mechanical stress, like when we bite and chew. Many products need large amounts of anti-microbial agents to maximize killing efficacy, which can weaken the mechanical properties and be toxic to tissues, but we showed that this material has outstanding mechanical properties and long-lasting antibiofilm activities without cytotoxicity," said Geelsu Hwang, research assistant professor at Penn Dental Medicine.

The newly developed material is comprised of a resin embedded with the antibacterial agent imidazolium. Unlike some traditional biomaterials that slowly release a drug, this material is nonleachable, thereby only killing the microbes that touch it. "This can reduce the likelihood of antimicrobial resistance," Hwang said.

Hwang and his colleagues put the material through its paces, testing its ability to kill microbes, prevent the growth of biofilms and withstand mechanical stress. The results showed it to be effective in killing bacterial cells on contact, severely disrupting the ability of biofilms to grow on its surface. Only negligible amounts of the biofilm matrix, the glue that holds clusters of bacteria together, were able to accumulate on the experimental material, in contrast to a control composite material, which showed a steady accumulation of sticky biofilm matrix over time.

​​​​​​​Following the initial tests, the team assessed how much shear force was required to remove the biofilm on the experimental material. While the smallest force removed almost all the biofilm from the experimental material, even a force four times as strong was incapable of removing the biofilm from the control composite material. "The force equivalent to taking a drink of water could easily remove the biofilm from this material," Hwang added.

The study, titled "Nonleachable imidazolium-incorporated composite for disruption of bacterial clustering, exopolysaccharide-matrix assembly, and enhanced biofilm removal," was published in the ACS Applied Materials and Interfaces journal on October 11 and was funded by Dentsply Sirona.

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