Dose-Response Meta-Analysis on Tooth Loss With the Risk of Cognitive Impairment and Dementia

Abstract

Objectives: To quantify the dose-response associations between tooth loss and risk of cognitive impairment and dementia.

Design: Longitudinal studies that examined the association between tooth loss and cognitive function were systematically searched on 6 databases through March 1, 2020. The study adhered to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) reporting guidelines. Risk estimates were pooled using random-effects models. The dose-response associations were assessed using generalized least squares spline models.

Setting and participants: Adults from community, institution, outpatient or in-hospital were included in the meta-analysis.

Measures: Cognitive impairment and dementia were defined by neuropsychological tests, diagnostic criteria, or medical records. Tooth loss was self-reported or assessed by clinical examinations.

Results: Fourteen studies were entered into the meta-analysis, including 34,074 participants and 4689 cases with diminished cognitive function. Participants with more tooth loss had a 1.48 times higher risk of developing cognitive impairment [95% confidence interval (CI) 1.18-1.87] and 1.28 times higher risk of being diagnosed with dementia (95% CI 1.09-1.49); however, the association was nonsignificant for participants using dentures (relative risk = 1.10, 95% CI 0.90-1.11). Eight studies were included in the dose-response analysis, and data supported the use of linear models. Each additional tooth loss was associated with a 0.014 increased relative risk of cognitive impairment and 0.011 elevated relative risks of dementia. Edentulous participants faced a 1.54 times higher risk of cognitive impairment and a 1.40 times higher risk of being diagnosed with dementia.

Conclusions and implications: Moderate-quality evidence suggested tooth loss was independently associated with cognitive impairment and dementia; risk of diminished cognitive function increased with incremental numbers of teeth lost. Furthermore, timely prosthodontic treatment with dentures may reduce the progression of cognitive decline related to tooth loss.

Keywords: Oral health; cognitive decline; meta-analysis; systematic review.

Figure 1.

Forest plot of tooth loss and risk of cognitive impairment (A) and dementia (B). Studies are pooled with a random-effects model; HEL, Higher education level, LEL, Lower education level

Figure 2.

Dose-response analysis of each one tooth loss increment and risk of cognitive impairment (A), dementia (B). The solid lines describe point estimates of the association between tooth loss and cognitive impairment or dementia risk; the dash lines represent 95% CIs