Introduction

It is well-established that cognitive impairment and loss of motor skills in elderly individuals can have a direct effect on oral health and the progression and/or severity of oral diseases, including dental caries and periodontal diseases.¹ Multiple recent reports have linked periodontitis, periodontal pathogens and byproducts, and tooth loss with dementias, including Alzheimer’s disease and other dementias.^1-3 A landmark study published in 2019 identified the presence of enzymes (gingipains) secreted by a bacteria commonly thought to be one of the keystone pathogens for periodontitis, Porphrymonas gingivalis (P.g.), in the brain tissues of individuals with pathology and symptoms of Alzheimer’s Disease at higher levels than in the brains of individuals without such symptoms.⁴ This report has re-ignited interest in the medical and lay communities in the potential role of periodontal diseases in development of Alzheimer’s and other dementias. It is, however, important to note that these findings are based upon a cross-sectional analysis of gingipain presence in tissues, which were found in 96% of all tissues assessed.⁴ This study builds upon earlier animal studies indicating that chronic oral application of P.g. bacteria or the gingipains produced by P.g. increase the production of amyloid beta, a protein indicated in the development of Alzheimer’s Disease.⁵ Further prospective randomized controlled trials are necessary to identify causation and/or common disease pathways between dementia and periodontitis. However, emerging evidence suggests that periodontal health may be critical in this population.

Periodontitis has been associated with dementia in epidemiologic studies; patients with periodontal disease are up to 70% more likely to present with Alzheimer’s Disease than those who are periodontally healthy.^6,7 It has been postulated that this relationship may be due to poorer oral hygiene over time due to deficits associated with dementia, dementia patients’ resistance to caregiver delivery of oral care resulting in a reduction of oral hygiene delivery, medication induced xerostomia, or other challenges associated with oral hygiene delivery for patients with dementia leading to larger dental plaque masses and/or more pathologic intraoral bacteria.^4-7 It has also been hypothesized that this interaction may be mediated by increases in local and systemic inflammation associated with both diseases, a dysbiotic oral microbiome, and/or immune reactions to oral pathogens.^8,9 Currently more than 55 million people live with dementia worldwide, and there are nearly 10 million new cases every year.¹⁰ Furthermore, global estimates suggest that the total economic costs caused by dementia increased from US $279.6 billion in 2000 to $948 billion in 2016, with an annual growth rate of nearly 16%.¹¹ It is also notable that the older segment of the population are retaining more teeth and retaining teeth for longer. Total edentulism in the US population is decreasing. Complete edentulism is expected to reach as low as 2.6% by 2050.¹² This represents a 30% decrease in complete edentulism, after we account for estimations of population growth and aging.¹² These changes in tooth retention may have a significant impact on the oral health status of older individuals.

Given the projected increased numbers of teeth in the elderly and the prevalence of dementia in that population, we can assume that more and more individuals with dementia will experience oral health challenges. Further, dementia and its sequelae and treatment may impact or health and oral disease, in particular periodontitis, have the potential for bidirectional influence. For example, medications for dementia often increase symptoms of xerostomia and higher caries rates are seen in patients with dementia, in particular those with moderate to severe disease and/or those that reside in residential nursing care facilities.^13,14 Conversely, periodontitis has been implicated in dementia disease progression.^4-7 Because of these interactions, it is critical that dental healthcare professionals are familiar with the medical impacts of oral disease and are able to counsel patients and caregivers about effective oral hygiene practices and interventions for dementia patients with caries and/or periodontal diseases.^15-17

Degeneration of cognitive function has been associated with worsening oral health parameters, including dental caries and periodontitis.^1,18-20 Large-scale epidemiologic studies have also shown that individuals with increased systemic inflammation, including elevated proinflammatory markers, have a higher risk of developing dementia and more rapid progression of dementia symptoms over time.^21-23 Given that periodontal diseases are initiated by dysbiotic biofilm, which then induces an inflammatory response that ultimately is responsible for soft and hard tissue destruction in the local periodontal environment. This inflammation-induced tissue destruction results in periodontal pocket formation, alveolar bone resorption, and finally, tooth loss.^24,25

In recent reports, periodontitis-associated local and systemic elevated inflammatory markers and dysbiotic oral bacteria/bacterial byproducts have been linked to dementia.^1-15,26-28 Dementia also presents additional behavior management challenges. Patients with dementia and their caregivers must manage delivery of preventative oral hygiene measures, which can be increasingly difficult as dementia severity increases.^29,30 Due to the number of individuals affected by both periodontal disease³¹ and dementia¹⁰ and the chronic, progressive nature of both diseases, the understanding of the interaction between periodontal disease and dementia and treatment strategies for promotion of optimal oral health in patients suffering with dementia is of utmost importance to the dental practitioner.