CRP and Alzheimer disease: Periodontitis is characterised as a low-grade systemic disease with the presence of gingival oedema, congestion, erythema, periodontal pockets, and loss of bone and soft tissue supporting the teeth,29,30 as well as release of pro-inflammatory cytokines into the systemic circulation, and an increase of C-reactive protein (CRP).11 PD is known to have multiple microbial aetiologies, and patients who eventually develop sporadic AD tend to have recurrent infections before clinical diagnosis of dementia.