The aging population makes the increase in cognitive disorders a challenge. One of the risk factors is old age, but also oral diseases, especially periodontitis, have been linked to an increased risk of dementia, especially Alzheimer's disease (AD), although research studies show varying correlations. Dental care utilization also decreases after a dementia diagnosis. The periodontal diseases are inflammatory disorders and common in the adult population. Periodontitis leads to loss of the supporting tissue of the tooth and, if untreated, to loss of teeth. Inflammation also plays a role in AD, the most common form of dementia. The reason for an association could be that periodontitis may lead to a spread of pro-inflammatory mediators and oral microorganisms to the brain. Another explanation suggests that chewing may stimulate nerve impulses and increase the blood flow to the brain. Fewer teeth could lead to less stimulation and reduced blood flow. In conclusion, oral diseases and dementia appear to be associated. Whether this connection constitutes a causal connection is more uncertain.