What readouts indicate a dysbiotic shift in periodontal biofilms in experimental models?

• A. Decreased pro-inflammatory cytokines
• B. Increased pro-inflammatory cytokines
• C. Reduction in RANKL/OPG ratio
• D. Increased pro-inflammatory cytokines, a higher RANKL/OPG ratio, expansion of red complex bacteria, reduction of commensals, and tissue inflammation markers

Answer: (D)

Dysbiosis in periodontal biofilms is a shift from a balanced, commensal community to a pathogenic state that both changes the microbial makeup and triggers an inflammatory host response. In experimental models, this is shown by the expansion of red complex bacteria, a reduction in commensal species, and the onset of tissue inflammation. The host response includes elevated pro-inflammatory cytokines, which drive tissue damage, and an increased RANKL/OPG ratio that promotes osteoclast-mediated bone resorption. Seeing all these signals together—more inflammatory mediators, a higher RANKL/OPG ratio, growth of red complex organisms, loss of commensals, and markers of tissue inflammation—best indicates a dysbiotic shift. Isolated cytokine increases or a lower RANKL/OPG ratio, by themselves, don’t capture the full dysbiotic biofilm transition.