Abstract
Early detection and subsequent reduction of modifiable risk factors for cognitive decline is important for extending healthy life expectancy in the currently aging society. Although a recent increase in studies on the state or number of the teeth and cognitive function, few studies have focused on the association between posterior teeth occlusion necessary to maintain chewing function and cognitive function among older adults. This study examined the association between posterior teeth occlusion and cognitive function in nursing home older residents. In this cross-sectional study, 279 residents aged ≥60 years from eight nursing homes in Aso City, Japan participated in cognitive function and dental status assessments and completed a comprehensive questionnaire survey in 2014. Cognitive function was measured using a Mini-Mental State Examination (MMSE). Posterior teeth occlusion was assessed using a total number of functional tooth units (total-FTUs), depending on the number and location of the remaining natural and artificial teeth on implant-supported, fixed, and removable prostheses. Linear regression models were used to assess univariate and multivariate associations between total-FTUs and MMSE scores. Models were sequentially adjusted for demographic characteristics, number of natural teeth, socioeconomic status, health behaviors, comorbidities, physical function, and nutritional status. Among the 200 residents included in our analysis, mean MMSE scores and total-FTUs were 11.0 ± 8.6 and 9.3 ± 4.6, respectively. Higher total-FTUs were significantly associated with higher MMSE scores after adjustment for demographics and teeth number (B = 0.48, 95% confidence interval [CI] = 0.22–0.74). The association remained significant even after adjustment for all covariates (B = 0.25, 95% CI = 0.01–0.49). The current findings demonstrated that loss of posterior teeth occlusion was independently associated with cognitive decline in nursing home older residents in Japan. Maintenance and restoration of posterior teeth occlusion may be a preventive factor against cognitive decline in aged populations.
Highlights
Cognitive impairment and dementia resulting from age-related decline in cognitive function are substantial public health concerns because they are common in older people and major causes of morbidity and mortality worldwide [1, 2]
These findings showed that total-FTUs significantly positively associated with Mini-Mental State Examination (MMSE) scores
The longest job, drinking history, Charlson Comorbidity Index (CCI), Barthel Index (BI), Mini Nutritional Assessment Short Form (MNA-SF), natural teeth number, and denture use that were significant at P < .20 were associated with MMSE scores, but denture use was not included in multivariate adjusted linear regression models because of multicollinearity with total-FTUs
Summary
Cognitive impairment and dementia resulting from age-related decline in cognitive function are substantial public health concerns because they are common in older people and major causes of morbidity and mortality worldwide [1, 2]. Early detection and subsequent reduction of modifiable risk factors for cognitive decline is important for extending healthy life expectancy in the currently aging society. Growing evidence suggests that dental health may be an important factor associated with cognitive function in aged populations. Prospective studies in several countries have reported positive relationships between natural teeth number and cognitive function [5, 6]. In a prospective study of older Japanese adults, those with few remaining natural teeth and without dentures had a significantly higher risk of dementia onset than those with 20 teeth [7]. Periodontal disease and caries, major reasons for tooth loss, are reported to be related to cognitive decline in a prospective study of U.S men [10]
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