Periodontitis, the chronic inflammatory disease of the supporting tissues of the teeth, has now been implicated in a variety of disparate systemic infections of various organs such as the lungs, heart, kidneys and brain. This review examines various associations involving chronic inflammatory processes arising from the periodontium and Alzheimer's disease, a progressive dementia of the brain with an as yet unknown origin. Causal pathways are also reviewed, e.g. the direct invasion of oral pathogens such as T. socranski and T. denticola from the periodontium across the blood-brain barrier, as well as common susceptibilities between the two tissues in terms of systemic dissemination from oral infections. Finally, potential anti-inflammatory therapies targeted at both the periodontium and brain are discussed, as periodontal infections are one of the treatable, preventable aetiopathologies involved in Alzheimer's disease. Keywords: association Alzheimer's periodontitis, bi-directional Alzheimer's periodontitis, curcumin Alzheimer's periodontitis, periopathogens Alzheimer's, periopathogens blood-brain barrier