BackgroundNumerous prospective studies have investigated the association between the number of remaining teeth and dementia or cognitive decline. However, no agreement has emerged on the association between tooth loss and cognitive impairment, possibly due to past studies differing in target groups and methodologies. We aimed to investigate the association between tooth loss, as evaluated through clinical oral examinations, and the development of cognitive impairment in community-dwelling older adults while considering baseline cognitive function.MethodsThis 4-year prospective cohort study followed 140 older adults (69.3% female) without cognitive impairment aged ≥65 years (mean age: 70.9 ± 4.3 years) living in the town of Ohasama, Iwate Prefecture, Japan. Cognitive function was evaluated with the Mini-Mental State Examination (MMSE) in baseline and follow-up surveys. Based on a baseline oral examination, the participants were divided into those with 0–9 teeth and those with ≥10 teeth. To investigate the association between tooth loss and cognitive impairment, we applied a multiple logistic regression analysis adjusted for age, sex, hypertension, diabetes, cerebrovascular/cardiovascular disease, hypercholesterolemia, depressive symptoms, body mass index, smoking status, drinking status, duration of education, and baseline MMSE score.ResultsIn the 4 years after the baseline survey, 27 participants (19.3%) developed cognitive impairment (i.e., MMSE scores of ≤24). Multiple logistic regression analysis indicated that participants with 0–9 teeth were more likely to develop cognitive impairment than those with ≥10 teeth were (odds ratio: 3.31; 95% confidence interval: 1.07–10.2). Age, male gender, and baseline MMSE scores were also significantly associated with cognitive impairment.ConclusionsTooth loss was independently associated with the development of cognitive impairment within 4 years among community-dwelling older adults. This finding corroborates the hypothesis that tooth loss may be a predictor or risk factor for cognitive decline.

Tooth loss was associated with greater risk of functional disability in community-dwelling elderly Japanese. Regular dental care might moderate the risk of functional disability in elderly individuals with missing teeth.

The purpose of the current study was to investigate the association between maximum occlusal force, which is an objective predictor of masticatory performance, and incident functional disability in an elderly Japanese population. A prospective cohort study was conducted targeting 815 (51.7% female) community-dwelling older adults aged ≥70 y residing in the Tsurugaya district, Sendai, Japan. The outcome measurement was incident functional disability, defined as a first certification of long-term care insurance in Japan, which is determined on the basis of a strictly established, uniform, nationwide standard. During a median follow-up of 7.9 y (interquartile range, 4.8-7.9 y), information on long-term care insurance was obtained from the Sendai Municipal Authority. Bilateral maximum occlusal forces of the participants were measured using a horseshoe-shaped pressure-indicating film, and the participants were categorized into quartiles based on occlusal force. Adjusted hazard ratios for functional disability were estimated with Cox proportional hazard models, adjusted for age, sex, body mass index, medical history, smoking status, alcohol consumption, duration of education, depressive symptoms, cognitive impairment, physical functioning, marital status, history of falls, and number of remaining teeth. The multiple-adjusted hazard ratios and 95% confidence intervals (CIs) for incident functional disability compared to the greatest occlusal force quartile were 1.53 (95% CI, 1.02-2.33), 1.64 (95% CI, 1.06-2.55), and 1.64 (95% CI, 1.01-2.68) for the third, second, and first quartiles, respectively (P for trend = 0.011). A lower maximum occlusal force was significantly associated with an increased risk of functional disability independently of possible confounders, including the number of remaining teeth. Occlusal force may be a useful indicator of the relationship between oral function and geriatric health.

Status of dentition was associated with incident functional disability in an elderly Japanese population. The findings of this study suggest that maintenance of remaining teeth and retention of occlusal supports contribute to the prevention of functional disability.

Objective This prospective study investigated the cross‐sectional association between impaired oral health‐related quality of life (OHRQoL) and the prevalence of depressive symptoms, and the longitudinal association between impaired OHRQoL and development of depressive symptoms among older adults. Background Previous studies have shown a relationship between poor oral health and depression among older adults; however, findings are inconsistent. Materials and Methods Participants were 669 community‐dwelling older Japanese individuals aged≥55 years (mean: 67.8 ± 7.2 years). Data of 296 participants were used for longitudinal analyses. OHRQoL was evaluated using the Oral Impacts on Daily Performances scale. Impaired OHRQoL was defined as the presence of at least one impact on the scale. Depressive symptoms were assessed using the Japanese version of the Zung self‐rating depression scale with a cut‐off score of 40. Results The cross‐sectional logistic regression model demonstrated that impaired OHRQoL was significantly associated with depressive symptoms (odds ratio [OR], 5.17; 95% confidence interval [CI], 2.99‐8.95) independent of age, sex, body mass index, hypertension, cerebrovascular/cardiovascular disease, smoking, drinking alcohol, education, cognitive function, objective oral health (dentition status) and oral health behaviour (dental visit within 1 year). Similarly, impaired OHRQoL predicted the development of depressive symptoms within 4 years in a fully adjusted longitudinal model (OR, 6.00; 95% CI, 1.38‐26.09). Conclusion Impaired OHRQoL was identified as a potential comorbidity of depressive symptoms and a predictor for depressive disorder later in life. OHRQoL may be a useful clinical outcome for elder patients with regard to their mental and oral health.