Periodontal disease and neuroinflammation: Exploring the oral–brain axis

Periodontal disease is a chronic inflammatory condition characterized by dysbiotic microbial biofilms and host-mediated tissue destruction. Increasing evidence suggests that periodontal inflammation may extend beyond the oral cavity and influence systemic health, particularly neurological disorders. The concept of the oral–brain axis proposes bidirectional communication between periodontal tissues and the central nervous system through microbial dissemination, systemic inflammatory mediators, immune activation, and vascular pathways. Neuroinflammation, a hallmark of neurodegenerative diseases such as Alzheimer’s disease and Parkinson’s disease, has been linked to chronic peripheral inflammatory sources including periodontitis. This narrative review aims to summarize current evidence regarding biological mechanisms connecting periodontal disease and neuroinflammation, including blood–brain barrier disruption, microglial activation, cytokine signaling, and microbial translocation. Clinical implications and future therapeutic perspectives are also discussed. Understanding the oral–brain connection may expand the role of periodontal therapy in systemic disease prevention and interdisciplinary healthcare. Although several studies have explored associations between periodontal disease and neurological disorders, a consolidated narrative integrating microbial, immunological, and vascular mechanisms within the framework of the oral–brain axis remains limited. This review aims to provide an updated synthesis of mechanistic pathways linking periodontal inflammation to neuroinflammatory processes while emphasizing emerging translational implications relevant to periodontal practice and interdisciplinary healthcare.