Stomatológ 2023, 33(2):15-22 | DOI: 10.69658/sto.2023.011

Association between tooth loss and disturbance of cognitive functions including dementia and Alzheimer disease. Review

Michal Straka^1,*, Peter Džupa², Marek Šupler¹

¹ Katedra zubného lekárstva, LF SZU

² Katedra dentálnej hygieny, FOaZOŠ SZU

In this extensive and comprehensive literature review, the authors focus on tooth loss with loss of occlusion and masticatory function and its impact on cognitive functions, dementia, and Alzheimer's disease. Currently, epidemiological studies have confirmed positive correlations between premature tooth loss and masticatory function with significant cognitive declines monitored through learning disabilities, including overcoming common life problems to early and advanced forms of dementia. Reducing the number of teeth, especially in the molar region, is considered to be a possible predictive factor of cognitive disorders. In addition to the epidemiological studies in this area, causal links between tooth loss and cognitive function failures have also been formulated, that can be summarized into 4 types of causality. The first is the association between insufficient mastication and reduced blood perfusion of the cerebral area, as signified by reduced vascular blood flow and continued hypoxia of essential brain centres. Another direct consequence of tooth loss is the termination of the relevant trigeminal sensorimotor networks from their initial mechanoreceptors in the periodontium up to the trigeminal centres in the brainstem, thus reducing neuronal networks and their branching in the locus coeruleus area. That is one of the centres of the adrenergic system involved in cognitive functions. The third group of factors detrimental to cognition and affecting the emergence of various demented conditions includes post-extraction disturbances in the function of nerve pathways that directly or indirectly cause neurodegenerative changes in many cerebral structures. Finally, a possible connection between chronic periodontitis and Alzheimer's disease may occur through the virulence factors of the primary bacterial pathogen of periodontitis, Porphyromonas gingivalis. Its gingipains and pathological tau proteins can infect trigeminal neurons terminating near the locus coeruleus, from where they can spread from the decayed neurons after extraction to the above structure and other subcortical nuclei in the brain. There, according to Braak's stages, Alzheimer's disease begins as was proven in an animal model. The basis for clinical practice lies in preventing premature tooth loss in consistent endodontic treatment of teeth with vital masticatory function for preserving the neural network between the peripheral jaws and many structures in the brain necessary for preserving cognitive functions. It is also crucial to treat all types of periodontitis and to transform the subgingival pathobiome into a healthy microbiome in the subgingival environment with the elimination of the main periodontal bacteria, especially Porphyromonas gingivalis, Tannerella forsythia, Aggregatibacter actinomycetemcomitans and Prevotela intermedia.

Keywords: tooth loss, loss of masticatory ability, afferent brain pathways n. trigeminus, subcortical brain nuclei, locus coeruleus, neurodegenerative changes in the brain, cognitive disorders, Alzheimer's disease

Published: December 15, 2023  Show citation