Researchers at the University of Minnesota have found that blocking chemical signals between oral bacteria can shift dental plaque toward health-associated microbial communities, without killing bacteria outright. The study, published in npj Biofilms and Microbiomes, focused on N-acyl homoserine lactones (AHLs), signaling molecules that oral bacteria use to coordinate group behaviour through a process called quorum sensing. When the researchers used enzymes called lactonases to block AHL signals in aerobic (above-gumline) conditions, health-associated bacteria increased. Adding AHLs under anaerobic conditions had the opposite effect, promoting growth of disease-linked late colonizers such as Porphyromonas gingivalis. The findings suggest that oxygen availability determines how quorum sensing shapes the plaque community, with different implications for tissue above and below the gumline. For periodontology, this points toward a treatment model based on steering microbial balance rather than broad antimicrobial suppression. Antibiotic resistance has made indiscriminate bacterial elimination increasingly problematic, and a targeted approach that preserves beneficial species could address that gap. The research team plans to map signaling differences across oral regions and across patients at different stages of periodontal disease, as a step toward clinical applications.