Antibiotic Exposure and Periodontal Susceptibility: A Risk-Modifying Hypothesis.

Systemic antibiotics are among the most widely prescribed therapeutic agents worldwide, and their effects on host-microbe equilibrium extend well beyond the infection for which they are intended. Periodontitis is conventionally framed as a biofilm-initiated, host-mediated inflammatory disease, although recent work has shifted this framework toward microbial homeostasis as a regulator of periodontal stability. We hypothesize that antibiotics are not direct etiologic agents of periodontitis but instead act as risk-modifying factors that lower the threshold at which plaque-mediated inflammation progresses to destructive disease. We propose that this effect may operate through several mechanisms: broad-spectrum or repeated exposure could deplete protective commensals and narrow microbial diversity, creating ecological space for opportunistic and pathogenic taxa; antibiotics may also alter host neutrophil function, cytokine profiles, and antimicrobial peptide regulation and may interfere with the osteoblastic and osteoclastic dynamics governing alveolar bone remodelling; and antibiotic-induced gut dysbiosis may propagate systemic inflammatory signals that further modulate periodontal susceptibility. To evaluate this hypothesis, we synthesize the available clinical, epidemiological, and experimental data across four converging axes-oral microbial ecology, immune regulation, alveolar bone remodelling, and the gut-oral axis-and identify the predictions the hypothesis generates and the evidence gaps it exposes. We emphasize that no clinical study has yet demonstrated a causal link between antibiotic exposure and periodontitis; the framework advanced here is therefore intended to inform antimicrobial stewardship in dentistry and to define a research agenda for determining whether antibiotic exposure constitutes a clinically meaningful modifier of periodontal disease susceptibility.