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.

The total number of natural teeth was related to swallowing function among older adults; however, limited information is available regarding the impact of occluding pairs of teeth on swallowing function. This study aimed to examine the association between posterior teeth occlusion and dysphagia risk in older nursing home residents. This cross-sectional study included 238 residents aged ≥60 years from eight nursing homes in Aso City, Japan. Swallowing function was evaluated using the modified water swallowing test (MWST); the primary outcome was dysphagia risk (MWST score ≤3). Posterior teeth occlusion was assessed using number of functional tooth units (FTUs), determined based on number and location of the remaining natural and artificial teeth on implant-supported, fixed or removable prostheses. Univariate and multivariate logistic regression analyses were performed to examine the association between posterior teeth occlusion and dysphagia risk, adjusted for the covariates of number of natural teeth, demographic characteristics, comorbidities, physical function, body mass index and cognitive function. Of the 238 subjects, 44 (18·5%) were determined to be at risk of dysphagia based on the MWST scores. The odds ratio (OR) of dysphagia risk decreased in subjects with higher total FTUs [OR = 0·92, 95% confidence interval (CI) 0·87-0·98]. After adjusting for covariates, this association remained significant (OR = 0·90, 95% CI 0·84-0·97). Loss of posterior teeth occlusion was independently associated with dysphagia risk in older nursing home residents. Maintaining and restoring posterior teeth occlusion may be an effective measure to prevent dysphagia.

Posterior teeth occlusion was independently associated with functional dependence among nursing home older residents in Japan. The maintenance and restoration of posterior teeth occlusion might be preventive factors against late-life functional decline. Geriatr Gerontol Int 2017; 17: 622-627.

Decreased cognitive function may be an independent predictor of dysphagia among dentulous and edentulous adults.

Methods for preventing aspiration pneumonia are needed soon in order to reduce mortality from aspiration pneumonia and promote the health of the elderly. The aim of this randomised controlled trial was to examine whether oral care with tongue cleaning improves coughing ability in elderly individuals living in geriatric care facilities. Participants comprised of 114 residents of 11 group homes and private nursing homes in Aso City in Kumamoto Prefecture. Participants were randomly assigned to either (i) a group that underwent routine oral care with tongue cleaning (intervention group; n = 58) or (ii) a group that underwent routine oral care alone (control group; n = 56). Coughing ability was evaluated by measuring peak expiratory flow (PEF) before and after 4 weeks of intervention. Before the intervention, PEF did not differ significantly between the intervention group (1·65 ± 1·11 L s ) and control group (1·59 ± 1·05 L s ; P = 0·658). However, on termination of the intervention, PEF was significantly higher in the intervention group (2·54 ± 1·42 L s ) than in the control group (1·90 ± 1·20 L s ; P = 0·014). After the intervention, PEF had increased significantly in both groups; however, this increase was significantly greater in the intervention group (0·90 ± 0·95 L s ) than in the control group (0·31 ± 0·99 L s ; P < 0·001). Oral care with tongue cleaning led to increased PEF, suggesting improved coughing ability. Oral care incorporating tongue cleaning appears to be important for preventing aspiration pneumonia.