Oral diseases as emerging risk factors for Alzheimer's disease: A scoping review

This scoping review examined current evidence on the relationship between oral diseases and Alzheimer's disease (AD). Systematic searches were conducted in PubMed, Scopus, Web of Science, Google Scholar, and KMbase for studies published from 1990 to December 2024, using terms of Alzheimer's disease, dementia, oral health, periodontal disease, dental caries, and tooth loss. Human and validated animal studies investigating microbiological, immunological, inflammatory, genetic, or functional links between oral health and AD were included. Of 1328 records, 841 remained after duplicates were removed, and 98 were reviewed in full; 45 met inclusion criteria. Findings were organized into four themes: general associations; periodontal disease and AD, including inflammation, amyloid-β pathways, and APOE4-related susceptibility; dental caries; and tooth loss with prosthetic rehabilitation. Evidence indicates that chronic oral diseases, especially periodontitis and tooth loss, are associated with increased risk of AD and its progression through mechanisms involving systemic inflammation, microbial translocation, amyloidogenic processes, genetic predisposition, and impaired masticatory function. Appropriate prosthetic rehabilitation may help reduce dementia risk by restoring chewing function and supporting nutrition. While causality has yet to be established, maintaining oral health throughout life may be a practical, cost-effective component of strategies to promote cognitive health in older adults.