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 Table of Contents  
ORIGINAL ARTICLE
Year : 2021  |  Volume : 13  |  Issue : 5  |  Page : 788-794  

Influence of dental prostheses on cognitive functioning in elderly population: A systematic review


1 Department of Prosthodontics and Crown and Bridge, Vinayaka Mission's Sankarachariyar Dental College, Vinayaka Mission's Research Foundation (Deemed to be University), Salem, Tamil Nadu, India
2 Department of Oral and Maxillofacial Surgery, Vinayaka Mission's Sankarachariyar Dental College, Vinayaka Mission's Research Foundation (Deemed to be University), Salem, Tamil Nadu, India
3 Department of Public Health Dentistry, Vinayaka Mission's Sankarachariyar Dental College, Vinayaka Mission's Research Foundation (Deemed to be University), Salem, Tamil Nadu, India

Date of Submission25-Nov-2020
Date of Decision30-Nov-2020
Date of Acceptance30-Nov-2020
Date of Web Publication05-Jun-2021

Correspondence Address:
Syed Ershad Ahmed
Department of Prosthodontics and Crown and Bridge, Vinayaka Mission's Sankarachariyar Dental College, Vinayaka Mission's Research Foundation (Deemed to be University), Salem - 636 308, Tamil Nadu
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jpbs.JPBS_773_20

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   Abstract 


Aim: The aim of the systematic review was to assess the influence of dental prostheses on cognitive functioning in elderly population. Materials and Methods: This systematic review was conducted according to the PRISMA guidelines. The initial electronic search was conducted using the following search databases: MEDLINE (PubMed), Cochrane Library, Google Scholar, and EMBASE. The search was limited to English language using the search items/keywords: “dental prostheses and cognitive functioning,” “dental prostheses and brain function,” “Tooth loss and cognitive loss,” “mastication and prefrontal activity,” and “prostheses on mental state.” The search strategy was followed using the PICOS framework. Results: A total of 19 studies were selected according to the selection criteria. Out of 19 studies, 15 studies were included and 4 studies were excluded from the review. Conclusion: With the available evidence in the literature, it can be concluded that dental prostheses have a very significant role in preventing the cognitive impairment and act as a protective factor in enhancing the cognitive function in patients with dementia-related diseases and neurodegenerative diseases.

Keywords: Brain function, cognition, denture prostheses, masticatory efficiency, prefrontal activity, tooth loss


How to cite this article:
Ahmed SE, Mohan J, Kalaignan P, Kandasamy S, Raju R, Champakesan B. Influence of dental prostheses on cognitive functioning in elderly population: A systematic review. J Pharm Bioall Sci 2021;13, Suppl S1:788-94

How to cite this URL:
Ahmed SE, Mohan J, Kalaignan P, Kandasamy S, Raju R, Champakesan B. Influence of dental prostheses on cognitive functioning in elderly population: A systematic review. J Pharm Bioall Sci [serial online] 2021 [cited 2021 Jul 29];13, Suppl S1:788-94. Available from: https://www.jpbsonline.org/text.asp?2021/13/5/788/317680




   Introduction Top


Cognitive decline is most common in elderly aged population, leading to dementia and Alzheimer's related problems. Loss of teeth in humans causes decreased neurodegenerative cognitive function, and many authors have shown that chewing efficiency is directly related to the number of teeth present in the oral cavity.[1] In the literature, it has been proved that mastication is closely related to cerebral cortex activity and also mastication tends to increase the cerebral blood flow leading to increased oxygen levels in the prefrontal and hippocampus area. Thus, reduced mastication brings about a decline in the cognitive capacity function. Therefore, in older adults to increase their chewing efficiency, replacement of missing teeth by oral rehabilitation is done.[2] Oral rehabilitation by dental prostheses directly aids in the simulation of the chewing-related cortices in the prefrontal and parietal sensorimotor areas enhancing the cognitive capacity of an individual and thereby decreasing the probabilities of dementia or Alzheimer's disease in an individual.[3],[4]

Oral health-related quality of life (OHRQoL) is a subjective assessment of an individual. Adults with decreased cognitive functions, dementia, Alzheimer's disease, and Parkinson's disease tend to have a greater impact on their quality of life (QoL). Tooth loss affects the esthetics, and rehabilitation with dental prostheses is done which aids in the enhancement of OHRQoL.[5],[6]

In the literature, no review has been done on the topic, so it was necessary to evaluate the review on this topic which is relevant in the current scenario. This systematic review aim is to analyze the literature data and consolidate the information regarding the impact of dental prostheses on the cognitive functioning in elderly individuals.


   Materials and Methods Top


This systematic review was conducted according to the PRISMA guidelines, and the research methodology was followed based on the Cochrane Handbook for Systematic Reviews of Interventions. The systematic review has been registered with PROSPERO (Registration number 210522). The review was conducted from January 2020 to July 2020.

Search strategy

The review included articles from the year 2000–2019. The initial electronic search was conducted by two investigators independently using the following search databases: MEDLINE (PubMed), Cochrane Library, Google Scholar, and EMBASE. The search was limited to English language using the search items/keywords: “dental prostheses and cognitive functioning,” “dental prostheses and brain function,” “teeth loss and cognitive loss,” “mastication and prefrontal activity,” and “prostheses on mental state.” In addition to the electronic search, hand search was also done by reviewing the references in the included studies. The search strategy was followed using the PICOS framework [Table 1].
Table 1: PICO framework

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Inclusion criteria

  1. Studies including patient group >60 years
  2. Studies following under criteria such as interventional studies, human studies, questionnaire studies, and cohort studies
  3. Studies involving patients falling under completely and partially edentulous category in the study group
  4. Studies showing a relation between dental prostheses (fixed or removable) and cognitive functioning
  5. Studies published only in English language.


Exclusion criteria

  1. Studies which do not clearly state the need of dental prostheses for better cognitive functioning
  2. Studies where the selected patient groups are <60 years in their selection criteria.


Screening and selection of studies

The screening and selection of the articles was done by two reviewers independently. Both the reviewers thoroughly discussed the selection criteria. Then, according to the inclusion and exclusion criteria, the reviewers screened the titles of the published records through electronic and hand search. Initially, the abstracts of all the articles were analyzed, and from the abstracts, the full text of the articles was selected and reviewed. Disagreement with the selection of the articles was sorted out by discussion. Cohen's kappa coefficient was used as a measure of agreement between the reviewers. The kappa score was 0.80 suggesting good interobserver agreement.

Data extraction and quality assessment

Data extraction was done based on the inclusion criteria by two reviewers independently. The studies were classified according to study design and outcome variables. Double checking was done by the reviewers.

The risk of bias in the articles included in this review was assessed according to the study verification checklist of the “Cohort of the Critical Appraisal Skills Programme”[7] [Table 2].
Table 2: Risk assessment of bias in articles (Cohort of Critical Appraisal Skills Programme)

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   Results Top


Selection criteria were based on the PRISMA statement flowchart [Figure 1]. A total of 19 studies were selected according to the selection criteria. Out of 19 studies, 15 studies were included and 4 studies were excluded from the review. For all the included studies, the data were tabulated with information about the type of study, year of publication, duration of study, number of patients, study groups, statistical method used, outcome, and inference. The data in the included studies were further tabulated according to various outcomes [Table 3], [Table 4], [Table 5], [Table 6].
Figure 1: PRISMA flowchart

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Table 3: Dentition and chewing ability on cognitive functioning

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Table 4: Prostheses and brain function/cognitive function

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Table 5: Prostheses and chewing ability on cognitive functioning

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Table 6: Mastication and cognitive functioning

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   Discussion Top


A projection shows by 2050 in low and middle income countries one in five persons are expected to attain age greater than 60 years. In India, the number of elderly people is expected to rise drastically due to increased life expectancy caused by newer technologies in the medical field. By 2100, in India, the number of elderly people will increase by one elderly for every three working-age populations. Studies show that persons with dementia are expected to double by 2030, and these would be seen mostly in developing countries like India.[8]

Cross-sectional studies have revealed that nutrition plays a major role in dental health and the importance of dental health in influencing the cognitive functioning.[9] Masticatory function is known to have an impact on the cardiac activity, and there are evidences of increased sympathetic stimulation and rise in oxygen levels in the prefrontal cortex and hippocampus area during chewing. A study conducted by Seraj et al. concludes that there is increased cognitive capacity and memory retrieval in elderly people having good chewing efficiency.[10]

Conventional denture prostheses and implant-supported prostheses significantly increase nutritional status and oral health perception in elderly people, thereby increasing their cognitive capacity.[11]

Various outcomes discussed in the included studies have shown the importance of dental prostheses on cognitive capacity of the individual. In this systematic review, a total of 15 studies were evaluated. The 15 studies had various outcomes, and these were categorized according:

  1. Dentition and chewing ability on cognitive functioning
  2. Prostheses and chewing ability on cognitive functioning
  3. Prostheses and brain function/cognitive function
  4. Mastication and cognitive function.


Dentition and chewing ability on cognitive functioning

Two studies evaluated the importance of number of dentition and chewing ability on the cognitive functioning. Seraj et al.[10] concluded in the study that people with low Mini-Mental State Examination (MMSE) scores had fewer number and teeth and impaired chewing ability, leading to decreased cognitive function. Fanny et al.[12] expressed the role of chewing efficiency in enhancing the cognitive functioning of the patient. The author concluded that the presence of limited teeth makes the surface area of the total occlusal table to be less, thus a reason for impaired chewing efficiency.

Prostheses and chewing ability on cognitive functioning

Five studies have shown in their research work about the importance of prostheses and chewing ability on cognitive functioning. Klotz et al.[4] suggested that tooth loss is directly related to a decline in chewing efficiency, and besides tooth loss, dementia also contributes to the impaired chewing efficiency. Narita et al.[13] concluded in the study that wearing partial denture leads to increased activation of dorsal prefrontal cortex and also an increased MmEEG activity. These results suggested that wearing partial denture prostheses stimulates the masticatory muscles and also helps in preventing the cognitive decline.

Kamiya et al.[1] have shown that there was no difference in chewing efficiency between elderly subjects and younger controls when wearing dental prostheses and prefrontal activity was also improved in elderly adults wearing prostheses. Ribeiro et al.[5] concluded that rehabilitation with removable prostheses improved their oral health QoL and also their mental assessment values, thus suggesting the importance of prostheses and chewing function on cognitive capacity of an individual. Yoshikawa et al.[14] suggest the role of dental prostheses in liquid swallowing. They concluded that subjects with prostheses had better ability in liquid swallowing and thus increasing their chewing efficiency.

Prostheses and Brain functioning

Banu et al.[15] have shown in the study the importance of prostheses over two implant-supported mandibular overdentures, and they have concluded that the mental state of the subjects was improved by the prostheses; this was due the functional activity of the prostheses rather than the mere existence of the implants without any function. Cerutti-Kopplin et al.[16] related the quality of denture to their function on improving the cognitive status of the individual. In the study, it was observed that masticatory ability was impaired in subjects with low functional assessment values of dentures, leading to decreased mental examination scores.

Hosoi et al.[17] reviewed the importance of brain function activity and denture treatment. The author conducted Electro Encephalo Gram measurements for the subjects, and it was concluded that brain function activation was increased after chewing in individuals wearing partial dentures, thus suggesting that occlusal contact area and occlusal force play an important role in brain function.

Ki et al.[2] highlighted the importance of dental implants in improving the cognitive function of patients. The author suggested that oral rehabilitation with dental implants with biosignal monitoring had a significant role in preventing the cognitive decline.

Okamoto[18] evaluated the effect of chewing on brain function with and without occlusal support on implant prostheses. The author concluded that the EEG and mandibular kinesiograph values increased among the impaired region group after gum chewing and also increased brain function when the total occlusal support area was increased. Shoi et al.[19] highlighted the importance of posterior tooth replacement on brain function. The author concluded that individuals with shortened dental arch had decreased brain activity (middle frontal gyrus) on chewing than the patients who were replaced with posterior tooth replacement.

Mastication and cognitive function

Campos et al.[20] concluded that mild Alzheimer's disease had decreased masticatory performance and low MMSE values. The results suggested that decreased masticatory performance leads to lower brain memory stimulation.

Kim et al.[21] evaluated the relationship between mastication and cognitive function. The author suggested that the use of dentures plays a significant role in enhancing the mastication and the increased masticatory performance aids in preventing the cognitive decline.


   Conclusion Top


Factors such as number of teeth present, total surface area of the occlusal table, and the masticatory efficiency correlate with the effect on prefrontal activity, leading to enhance cognitive function. Data analyzed in this systematic review suggested that dental prostheses have a very significant role in preventing the cognitive impairment and act as a protective factor in enhancing the cognitive function in patients with dementia-related diseases and neurodegenerative diseases.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

1.
Kamiya K, Narita N, Iwaki S. Improved prefrontal activity and chewing performance as function of wearing denture in partially edentulous elderly individuals: Functional near-infrared spectroscopy study. PLoS One 2016;11:e0158070.  Back to cited text no. 1
    
2.
Ki S, Yun J, Kim J, Lee Y. Association between dental implants and cognitive function in community-dwelling older adults in korea. J Prev Med Public Health 2019;52:333-43.  Back to cited text no. 2
    
3.
Chuhuaicura P, Dias FJ, Arias A, Lezcano MF, Fuentes R. Mastication as a protective factor of the cognitive decline in adults: A qualitative systematic review. Int Dent J 2019;69:334-40.  Back to cited text no. 3
    
4.
Klotz AL, Hassel AJ, Schroder J, Rammelsberg P, Zenthofer A. Oral health-related quality of life and prosthetic status of nursing home residents with or without dementia. Clin Interv Aging 2017;12:659-65.  Back to cited text no. 4
    
5.
Ribeiro GR, Campos CH, Rodrigues Garcia RC. Influence of a removable prosthesis on oral health-related quality of life and mastication in elders with Parkinson disease. J Prosthet Dent 2017;118:637-42.  Back to cited text no. 5
    
6.
Ming Y, Hsu SW, Yen YY, Lan SJ. Association of oral health-related quality of life and Alzheimer disease: A systematic review. J Prosthet Dent 2020;124:168-75.  Back to cited text no. 6
    
7.
Gray M, Brice R, Moore S, et al. CASP Checklists – CASP – Critical Appraisal Skills Programme (Internet). CASP – Critical Appraisal Skills Programme; 2018.  Back to cited text no. 7
    
8.
Sathianathan R, Kantipudi SJ. The dementia epidemic: Impact, prevention, and challenges for India. Indian J Psychiatry 2018;60:165-7.  Back to cited text no. 8
[PUBMED]  [Full text]  
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Lindawati K, Nathanae M, Dyas R, Indrasari M, Masulili C, et al. Impact of using denture on cognitive function in the elderly. J Int Dent Medical Res 2016;9:287-92.  Back to cited text no. 9
    
10.
Seraj Z, Al-Najjar D, Akl M, Aladle N, Altijani Y, Zaki A, et al. The effect of number of teeth and chewing ability on cognitive function of elderly in UAE: A pilot study. Int J Dent 2017;2017:5732748.  Back to cited text no. 10
    
11.
El Osta N, El Osta L, Moukaddem F, Papazian T, Saad R, Hennequin M, et al. Impact of implant-supported prostheses on nutritional status and oral health perception in edentulous patients. Clin Nutr ESPEN 2017;18:49-54.  Back to cited text no. 11
    
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Elsig F, Schimmel M, Duvernay E, Giannelli SV, Graf CE, Carlier S, et al. Tooth loss, chewing efficiency and cognitive impairment in geriatric patients. Gerodontology 2015;32:149-56.  Back to cited text no. 12
    
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Narita N, Kamiya K, Yamamura K, Kawasaki S, Matsumoto T, Tanaka N. Chewing-related prefrontal cortex activation while wearing partial denture prosthesis: Pilot study. J Prosthodont Res 2009;53:126-35.  Back to cited text no. 13
    
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Yoshikawa M, Yoshida M, Nagasaki T, Tanimoto K, Tsuga K, Akagawa Y. Influence of aging and denture use on liquid swallowing in healthy dentulous and edentulous older people. J Am Geriatr Soc 2006;54:444-9.  Back to cited text no. 14
    
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Banu RF, Veeravalli PT, Kumar VA. Comparative evaluation of changes in brain activity and cognitive function of edentulous patients, with dentures and two-implant supported mandibular overdenture-pilot study. Clin Implant Dent Relat Res 2016;18:580-7.  Back to cited text no. 15
    
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Cerutti-Kopplin D, Emami E, Hilgert JB, Hugo FN, Padilha DM. Cognitive status of edentate elders wearing complete denture: Does quality of denture matter? J Dent 2015;43:1071-5.  Back to cited text no. 16
    
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Hosoi T, Masakazu M, Naoyuki S, Yoshikazu Y. Influence of denture treatment on brain function activity. Jpn Dent Sci Rev. 2011;47:56-66.  Back to cited text no. 17
    
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Okamoto N. Effect of occlusal support by implant prostheses on brain function. J Prosthodont Res 2011;55:206-13.  Back to cited text no. 18
    
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Shoi K, Fueki K, Usui N, Taira M, Wakabayashi N. Influence of posterior dental arch length on brain activity during chewing in patients with mandibular distal extension removable partial dentures. J Oral Rehabil 2014;41:486-95.  Back to cited text no. 19
    
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Campos CH, Ribeiro GR, Costa JL, Rodrigues Garcia RC. Correlation of cognitive and masticatory function in Alzheimer's disease. Clin Oral Investig 2017;21:573-8.  Back to cited text no. 20
    
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    Figures

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    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]



 

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