<i>Porphyromonas gingivalis</i> and pain modulation: a narrative review

Background: Although the relationship between gut bacteria and pain is increasingly well understood, research on the role of oral bacteria in pain remains limited.Porphyromonas gingivalis (P.gingivalis), a major pathogen in periodontal disease, is known to drive the progression of infection in the oral cavity, leading to inflammation and tissue destruction.However, unlike other conditions, patients with periodontal disease exhibit variable pain responses.This unique presentation suggests that P. gingivalis exerts multifaceted effects on pain modulation.Methods: The bibliographic databases of PubMed, Embase, Google Scholar, and the Cochrane Library were searched for original and reviewed in vitro, animal, and human studies.Key data on pain, inflammation, and neuroimmune pathways were extracted.Studies that did not address pain mechanisms or were limited to non-oral/systemic conditions without a clear link to orofacial pain were excluded.Results: This review summarizes the current evidence on how P. gingivalis influences inflammation and pain, highlighting the interactions between its cell wall components (e.g., lipopolysaccharide and fimbriae), metabolic byproducts (e.g., nitric oxide and butyric acid), and the host immune response. Conclusion:The diverse pain manifestations in P. gingivalis-induced periodontitis may reflect the different stages of disease.Early pain suppression may result from bacterial immune evasion, wherein therapies adjunctive to scaling and root planing, such as host modulation therapy or gingipain inhibitors, may help restore host immunity and improve clinical outcomes.