Experiments using radial arm mazes show that mice and rats have difficulties finding food when their chewing capability is disturbed after molar extraction. Observations of this kind have indicated an association between mastication and cognition. Experimental evidence show increased blood stream and neuronal activity in young individuals using chewing gum. Some experiments also indicate that memory and other cognitive functions improve during chewing. Observations of this kind have led to the concept that inferior mastication also may have an impact on the development of age related dementia.

A series of epidemiological investigations confirm the association between loss of teeth and dementia, although the causation is uncertain. Some researchers propose that loss of masticatory stimulus may induce failures of neuronal activity. Others point to the fact that tooth loss is most often caused by a bacterial disease such as periodontitis, causing infectious agents and inflammatory host reactions to induce the microglia cells of brain tissue to reactions ending with neuronal death. At present, the inflammation hypothesis has the most credibility in neurological and psychological research. However, it is underlined that the association between oral disease and cognitive failure among older people does not necessarily indicate a causal relationship, because many circumstances related to dementia may cause poor oral health.

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References

Oral helse og kognitiv funksjon
Jacobsen N
Nor Tannlegeforen Tid. 2016; 126: 344-349 

Oral helse og kognitiv funktion
Jacobsen N
Tandlægebladet 2016; 10: 906-12