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Table 1 Conclusion from the systematic review and meta-analysis on clinical and epidemiological research published in the past five years

From: Revisiting the link between cognitive decline and masticatory dysfunction

Search criteria: 1. Key word combination: (chewing OR masticat* OR “tooth loss” OR “teeth loss” OR “number of teeth”) AND (cognit* OR memory OR dement*) AND (“systematic review” OR meta-analysis) 2. Language: English 3. Publication date: 2012.10.15–2017.10.15
Reference Criteria of study selection Number of studies included Major findings or conclusion (direct quotation)
Tonsekar et al. 2017 [13] Publications on the relation between periodontitis, tooth loss and dementia Total: 8a PT:4 RT:3 ‘The literature on chronic periodontitis and multiple tooth loss as risk factors to dementia remains inconclusive.’
Tada and Miura 2017 [11] Publications that assessed associations between mastication and cognitive function, cognitive decline and dementia among population over 40 years old Total: 33 CS:22 PT:11 ‘Most studies point to a positive association between mastication and cognitive function, including dementia among elderly people.’
Wu et al. 2016 [12] Publications that examined the effect of oral health on change in cognitive health or dementia incidence, or the publications that examined the reverse effect. Total: 11b (all longitudinal studies) ‘Similarly, cognitive decline was not consistently associated with greater loss of teeth or number of decayed teeth.’
Delwel et al. 2016 [14] Publications about oral health and orofacial pain Comparison was made between the older people with and without dementia. Total: 19c CS: 9 CC: 3 RCT: 1 Longitudinal: 6 ‘……they had an equivalent number of teeth present, similar rate of edentulousness, and equivalent decayed missing filled teeth index.’
Cerutti- Kopplin et al. 2016 [9] Publications on the association between oral health and cognitive function, via prospective cohort study designs Total: 10 PT: 10 ‘Within the limits of the quality of published evidence, this meta-analysis lends further support to the hypothesis that tooth loss is associated with an increased risk of cognitive impairment and dementia.’
  1. CC Case-control studies, CS cross-sectional studies, PT prospective studies, RCT randomized controlled trials, RT retrospective studies
  2. aOnly the studies of human subjects
  3. bOnly the studies using the data from oral health status to predict cognitive status
  4. cOnly the studies that reported the number of present teeth