THC killed the main cavity-causing bacteria in lab tests and blocked its ability to form harmful biofilms

THC inhibited S. mutans growth at an MIC of 2 micrograms/mL (p < 0.0001). At this concentration, THC reduced bacterial acid production and inhibited over 90% of biofilm formation. THC also reduced biofilm viability and extracellular polysaccharide production at 1 microgram/mL or above. While THC did not degrade preformed biofilm biomass, it reduced its metabolic activity and viability. The mechanism appeared to involve membrane hyperpolarization.

In vitro study testing THC against S. mutans using antimicrobial susceptibility testing (MIC), crystal violet biofilm assay, MTT metabolic activity assay, live/dead viability assay, Cascade Blue Dextran EPS staining, and membrane potential detection.

This is the first systematic in vitro study of THC's effects on the primary bacterium responsible for dental cavities. While it does not mean cannabis prevents cavities, it identifies a potentially useful antimicrobial property of THC.

This is an unexpected potential application for THC. If these in vitro findings translate, THC-based compounds could theoretically be developed as anticariogenic agents, though many steps remain between a lab finding and a dental product.

In vitro results may not reflect conditions in the human mouth. THC concentrations tested may not be achievable via normal cannabis use. Could not degrade existing biofilm. Psychoactive effects of THC make direct oral application impractical without modification.