Cannabidiol (CBD) and cannabigerol (CBG) significantly inhibited the formation of cavity-causing dental biofilms and disrupted already-established biofilms in a new laboratory study.
The study, published in the International Dental Journal, examined CBD and CBG against biofilms containing both Streptococcus mutans and Candida albicans, two microorganisms that can interact in dental plaque and contribute to tooth decay. Researchers from Henan University and the University of Rochester Medical Center were among the study’s authors.
Researchers said that while previous studies have found antimicrobial and antibiofilm effects from cannabinoids against the organisms individually, substantially less was known about how CBD and CBG would perform against mixed-species biofilms, which can be more difficult to control and more closely resemble the microbial environment found in the mouth.
For the study, researchers created biofilms containing S. mutans and C. albicans, including models grown on saliva-coated hydroxyapatite discs designed to mimic tooth enamel. They examined whether CBD and CBG could prevent biofilm development as well as whether they could disrupt mature biofilms that had already formed.
Both cannabinoids showed substantial effects.
When 5 milligrams per milliliter of CBD or CBG was introduced as the biofilms were forming, researchers reported a 96% reduction in metabolic activity and an 80% reduction in biofilm biomass compared with untreated controls.
The effects also continued after the cannabinoids were removed. Following an additional 24-hour recovery period in a highly cavity-promoting environment, metabolic activity remained 79% lower in the CBD group and 90% lower in the CBG group. Biofilm biomass remained 55% lower with CBD and 62% lower with CBG.
Researchers then tested the cannabinoids against mature biofilms that were allowed to develop for 24 hours before treatment.
After repeated treatment, CBD reduced viable S. mutans levels by 92% after 48 hours and 95% after 72 hours. CBG reduced the bacteria by 90% and 92%, respectively. CBD performed significantly better than CBG at the 72-hour measurement.
CBD also substantially altered the physical structure of the biofilms. When used during biofilm formation, it reduced microbial biomass by more than 99%, extracellular polysaccharide biomass by 81% and average biofilm thickness to about 21% of the untreated control. When applied to mature biofilms, CBD reduced microbial content by more than 20%, extracellular polysaccharides by 23% and average thickness by 22%.
Both cannabinoids also reduced acid production. This is potentially important because acids produced by oral microorganisms contribute to enamel demineralization and the development of cavities.
Genetic analysis found that CBD altered hundreds of genes in both microorganisms, including pathways associated with biofilm fitness, metabolism, stress response and virulence. Researchers said the findings suggest CBD may do more than simply kill bacteria, instead changing biological processes that help the mixed-species biofilm survive and cause disease.
The authors said this appears to be the first study to examine CBD and CBG specifically in S. mutans–C. albicans dual-species communities.
However, the research was conducted in vitro, not in humans. The authors cautioned that laboratory biofilms cannot fully reproduce dental plaque, saliva, dietary changes or the human immune system, and said further research is needed to determine appropriate formulations, doses and safety for potential oral-health applications.
The researchers concluded that CBD and CBG reduced cavity-associated characteristics of the mixed bacterial-fungal biofilms and said the findings provide a basis for future studies using more complex oral biofilm models.
