Tooth Loss, Denture Use and Cognitive Impairment in Chinese Older Adults: A Community Cohort Study

Association Between Subjective Masticatory Function and Mild Cognitive Impairment in Older Adults

AIM

This study aimed to examine the effect of subjective masticatory function on the occurrence of mild cognitive impairment (MCI) by analysing the Korean Longitudinal Study of Ageing (KLoSA) data.

METHODS

The study participants were 2954 KLoSA participants aged 60 years or older in the first wave (2006) who had normal cognitive function. The subjective masticatory function was determined using a survey item, and the responses were grouped into 3 categories, ie, good, moderate, and poor. The occurrence of MCI in the 3 groups was followed up until 2020. Cognitive function was assessed based on the Korean Mini-Mental State Examination score. Age, sex, education level, residence, health insurance type, smoking status, drinking status, and the number of chronic diseases were considered as potential confounders. To examine the occurrence of MCI according to subjective masticatory function, Cox proportional hazard regression analysis was performed.

RESULTS

Cox proportional hazard regression models adjusted for confounders yielded the following results: in men, the risk of MCI was higher in those whose subjective masticatory function was moderate and poor, as compared to those with good subjective masticatory function (adjusted hazard ratio [aHR], 1.33; 95% confidence interval [CI], 1.12-1.58; aHR, 1.23; 95% CI, 1.04-1.46). In contrast, in women, subjective masticatory function did not significantly influence the occurrence of MCI (aHR, 1.05; 95% CI, 0.89-1.24; aHR, 1.08; 95% CI, 0.92-1.28).

CONCLUSIONS

This study suggests that poor masticatory function may be a risk factor for MCI in older men.

The relationship between oral status and healthy aging in Chinese older adults: A community cohort study

OBJECTIVES

In recent years, there has been a growing academic interest in investigating the determinants of healthy aging. The main objective of this study was to investigate the association between oral status, as defined by tooth loss and denture use, and healthy aging among Chinese older adults over a four-year duration.

METHODS

The data were derived from the 2014 and 2018 waves of the Chinese Longitudinal Healthy Longevity Survey. Descriptive statistics and multivariate logistic regression analysis were employed for statistical analysis.

RESULTS

The results suggest that older adults with ≥20 natural teeth have a higher likelihood of experiencing healthy aging compared to those with fewer than 20 natural teeth. In the fully adjusted model, only older adults with ≥20 natural teeth demonstrated a higher rate of healthy aging compared to those with 0 natural teeth, with an OR (95% CI): 2.09 (1.54-2.84).

CONCLUSIONS

These results highlight the importance of maintaining ≥20 teeth for promoting healthy aging among Chinese older adults. Furthermore, wearing dentures can, to varying degrees, mitigate the adverse effects of tooth loss on healthy aging. Rehabilitative interventions, such as the utilization of dentures and other clinical strategies, play a pivotal role in enhancing the oral health status of older individuals.

Physical frailty intensifies the positive association of oral frailty with poor global cognitive function and executive function among older adults especially for females: a cross-sectional study

BACKGROUND

Oral frailty is reported to increase the risk of new onset of mild cognitive impairment. Whereas, the association of oral frailty with cognition among older adults in both physical frail and non-physical frail status has not been sufficiently explored, and whether there are sex differences in the association is unclear. This study investigated the association of oral frailty and physical frailty with global cognitive function and executive function among older adults, as well as the sex differences in such association.

METHODS

This cross-sectional study included 307 participants aged ≥ 60 years old from communities between June 2023 and August 2023, in Nanjing, China. Global cognitive function and executive function were assessed by using the Montreal Cognitive Assessment (MoCA) and Trail Making Tests A (TMT-A), respectively. Oral frailty was identified by the combination of natural tooth, Oral Frailty Index-8 (OFI-8), and oral diadochokinesis. Physical frailty was measured by using Fried phenotype model which contained 5 criteria: unintentional weight loss, weakness, exhaustion, slowness, and low physical activity. Multiple linear regression analyses for overall participants and stratified by sex and presence or absence of physical frailty were performed, respectively, to examine the association between oral frailty and cognitive functions.

RESULTS

The median age of participants was 70 years old. The study included 158 (51.5%) females, 53 (17.3%) individuals with physical frailty, and 65 (21.2%) participants with oral frailty. After adjustment, the association between oral frailty and global cognitive function was observed in the physical frailty group (B = -2.67, 95% Confidence Interval [CI]: -5.27 to -0.07, p = 0.045) and the females with physical frailty (B = -4, 95% CI: -7.41 to -0.58, p = 0.024). Oral frailty was associated with executive function in overall participants (B = 0.12, 95% CI: 0.01 to 0.22, p = 0.037), physical frailty group (B = 23.68, 95% CI: 1.37 to 45.99, p = 0.038). In the adjusted models, oral frailty was significantly associated with executive function in all females (B = 0.21, 95% CI: 0.05 to 0.36, p = 0.009), in females without physical frailty (B = 0.19, 95% CI: 0.02 to 0.36, p = 0.027), and in females with physical frailty (B = 48.69, 95% CI: 7.17 to 90.21, p = 0.024).

CONCLUSIONS

Physical frailty intensifies the positive association of oral frailty with poor global cognitive function and executive function among older adults, particularly among females. It is ponderable to consider sex differences and facilitate the management of physical frailty when it comes to promoting cognitive health based on the perspective of oral health among older adults.

Functional teeth and cognitive function among the Chinese elderly: The chain mediating effect of depressive symptoms and social participation

The objective of this study was to investigate the chain mediating effects of depressive symptoms and social participation between functional teeth and cognitive function based on the biopsychosocial model. Data from the 2018 China Health and Retirement Longitudinal Study were analyzed. The findings revealed a favorable connection between the lack of edentulism and cognitive function, persisting even when accounting for the mediating factors of denture usage, depressive symptoms, and social participation. Furthermore, the study identified six indirect pathways in this relationship. The present study has substantiated the correlation between edentulism and cognitive function, thereby proposing that interventions aimed at denture usage, depressive symptoms, and social participation could potentially serve as preventive measures against cognitive decline in elderly individuals afflicted with edentulism. This underscores the significance of addressing these factors to alleviate cognitive decline.

Association of tooth location, occlusal support and chewing ability with cognitive decline and incident dementia

AIM

Emerging evidence suggests association of tooth loss with impaired cognition. However, the differential effects of anterior versus posterior tooth loss, occlusal support loss and chewing ability are not considered comprehensively.

MATERIALS AND METHODS

We conducted cross-sectional (N = 4036) and longitudinal analyses (N = 2787) on data from Health 2000 and 2011 Surveys for associations of posterior occlusal support loss, anterior versus posterior tooth loss, and chewing ability with baseline cognition and 11-year cognitive decline. Additionally, 15-year incident dementia risk was investigated (N = 4073).

RESULTS

After considering relevant confounders and potential reverse causality bias, posterior occlusal support loss significantly increased dementia risk across all categories indicative of posterior occlusal support loss (hazard ratios [HRs] between 1.99 and 2.89). Bilateral inadequate posterior occlusal support was associated with 11-year decline in overall cognition (odds ratio [OR] = 1.48:1.00-2.19), and unilateral inadequate posterior occlusal support with total immediate (OR = 1.62:1.14-2.30) and delayed recall decline (OR = 1.45:1.03-2.05). Moreover, posterior tooth loss was associated with dementia (HR = 2.23:1.27-3.91) and chewing ability with total immediate decline (OR = 1.80:1.04-3.13).

CONCLUSIONS

Posterior tooth and occlusal support loss significantly increases dementia risk. The impact of posterior occlusal support loss appears to be dose-dependent, and this effect is distinct from that of dentures. Dental healthcare services should be particularly attentive to the state of posterior dentition. Further studies exploring possible mechanisms are warranted.

Association of Denture Use and Chewing Ability with Cognitive Function Analysed Using Panel Data from Korea Longitudinal Study of Aging (2006-2018)

This study aimed to investigate the association between denture use, chewing ability, and cognitive function in Korean middle-aged adults, using samples representing middle-aged people at the national level. This longitudinal study included 9998 middle-aged adults using the Korea Longitudinal Study of Aging 7th special survey data. Denture use, chewing ability, health-related factors, and general characteristics were assessed using the Computer-Assisted Personal Interview. After controlling for general characteristics using a generalized estimating equation model, the association of denture use and Mini-Mental State Examination (MMSE) scores with the chewing ability of those with or without dentures and MMSE scores were analysed. Among them, 24% of participants wore dentures, and 35.1% complained of difficulty chewing when wearing dentures. Among the participants who did not wear dentures, 16.4% complained of difficulty chewing. MMSE scores were lower among denture wearers than non-denture wearers (β = -0.026, p < 0.001). In both groups, MMSE scores decreased with chewing difficulty and were significantly reduced among non-denture wearers (p < 0.05). Chewing ability was closely associated with cognitive functioning. Therefore, in order to prevent cognitive decline, chewing discomfort while wearing dentures must be eliminated, and oral health must be maintained.

Association of tooth count with cognitive decline and dementia in the Finnish adult population

AIM

To evaluate whether tooth loss is associated with cognitive decline and incident dementia.

MATERIALS AND METHODS

We analysed data from the Finnish population-based Health 2000 and follow-up Health 2011 surveys (participants aged ≥30 years and without dementia at baseline; N = 5506 at baseline and 3426 at 11-year follow-up). Dementia diagnoses until 2015 were ascertained from national registers (N = 5542). Tooth count was dichotomized as adequate (≥20) versus tooth loss (<20). Tooth loss was further stratified into 10-19 teeth, 1-9 teeth and edentulism. Upper and lower jaws were also considered separately. Baseline cognitive test scores were dichotomized by median as high versus low, and 11-year change as decline versus no decline.

RESULTS

Tooth loss (<20) was associated with lower baseline overall cognition (odds ratio [OR] = 1.21, 95% confidence interval [CI] = 1.03-1.43), 11-year cognitive decline (OR = 1.30, 95% CI = 1.05-1.70) and higher 15-year dementia risk (hazard ratio = 1.52, 95% CI = 1.15-2.02) after adjusting for multiple confounders. After adjustment for dentures, associations became non-significant, except for 10-19 teeth remaining and dementia. Results were similar after considering reverse causality bias; however, 10-19 teeth remaining was significantly associated with 11-year cognitive decline even after adjustment for dentures. No jaw-specific differences were observed.

CONCLUSIONS

Tooth loss adversely impacts the risk of cognitive decline and dementia. The role of dentures should be further explored.

Tooth Loss, Periodontal Disease, and Mild Cognitive Impairment Among Hispanic/Latino Immigrants: The Moderating Effects of Age at Immigration

BACKGROUND

The objectives were to assess (a) the association between poor oral health and mild cognitive impairment (MCI) in Hispanic/Latino immigrants and (b) potential modification effects on this association by age at immigration.

METHODS

Data were from the Hispanic Community Health Study/Study of Latinos and its ancillary study-the Study of Latinos-Investigation of Neurocognitive Aging. MCI, a binary outcome variable, defined by the National Institute on Aging-Alzheimer's Association criteria. The main exposure was significant tooth loss (STL), defined as a loss of 8 or more teeth, and periodontitis, classified using the Centers for Disease Control and Prevention and American Academy of Periodontology case classification. Multiple logistic regression was used to assess the association between STL/periodontitis and MCI and test moderation effects of age at immigration. The analytical sample comprised 5 709 Hispanic/Latino adult immigrants.

RESULTS

Hispanic/Latino immigrants with STL (adjusted odds ratio [AOR] = 1.36, 95% confidence interval [CI]: 1.01-1.85) were more likely to have MCI than those with greater tooth retention. Overall, migration to the United States after age 18 was associated with greater odds of MCI than migration at a younger age. A significant interaction effect between STL and age at immigration revealed that the effect of STL on MCI is even higher in those who immigrated to the United States at ages 35-49 years.

CONCLUSIONS

STL is a significant risk factor for MCI and age at immigration had a modification effect on the association between STL and MCI. Better access to dental care, health education on risk factors of MCI, and promotion of good oral health may mitigate the burden of cognitive impairment in Hispanics/Latinos.

Association of the number of natural teeth with dietary diversity and nutritional status in older adults: A cross-sectional study in China

AIM

To investigate the association of the number of natural teeth with overall dietary diversity and nutritional status in a nationally representative study among older adults in China.

MATERIALS AND METHODS

A cross-sectional analysis was conducted among community-dwelling adults aged 65 years or older from the Chinese Longitudinal Healthy Longevity Study. According to the self-reported number of natural teeth, participants were categorized into ≥20, 10-19, 1-9 natural teeth, and edentulous. Dietary diversity score (DDS) was constructed based on intake frequencies of 10 food groups assessed by a simplified food frequency questionnaire. The geriatric nutritional risk index was used to measure the malnutrition status (i.e., normal, mild malnutrition, and moderate-to-severe malnutrition) among a subgroup of participants. Linear and multinomial logistic regression models were used to examine the corresponding associations.

RESULTS

Among 54,796 study participants, the mean (SD) age was 87.86 (11.45) years, 82.7% had poor dentition (<20 natural teeth), and 27.3% wore dentures. After multivariable adjustment, participants with poor dentition had lower DDSs (β_edentulous  = -0.39, 95% confidence interval [CI], -0.48, -0.30; β_{1-9 teeth}  = -0.46, 95% CI, -0.55, -0.37; β_{10-19 teeth}  = -0.36, 95% CI, -0.46, -0.26) than those with 20 natural teeth or more. For individual food items, edentulous, 1-9 and 10-19 natural teeth were associated with lower odds of regular intake of fresh fruits, fresh vegetables, meat, fish and aquatic products, eggs, legumes, preserved vegetables, tea, and garlic, but higher odds of regular intake of sugar and sweets. Among participants with poor dentition, individuals without dentures had lower intake frequencies of most food groups than those wearing dentures. In addition, poor dentition was related to lower odds of normal nutritional status (odds ratio = 0.49, 95% CI, 0.27, 0.89).

CONCLUSIONS

Older adults with poor dentition had significantly lower dietary diversity and worse nutritional status. Future studies are warranted to identify effective interventions to improve the dietary quality and nutrition status among partially and fully edentulous individuals, including those with Stage IV periodontitis.

Tooth loss and the risk of cognitive decline and dementia: A meta-analysis of cohort studies

Introduction

Epidemiological studies have shown that tooth loss may be associated with an increased risk of cognitive decline and dementia. However, some results do not show a significant association. Therefore, we performed a meta-analysis to evaluate this association.

Methods

Relevant cohort studies were searched in PubMed, Embase, Web of Science (up to May 2022), and the reference lists of retrieved articles. The pooled relative risk (RR) and 95% confidence intervals were computed using a random-effects model (CI). Heterogeneity was evaluated using the I ² statistic. Publication bias was evaluated using the Begg's and Egger's tests.

Results

Eighteen cohort studies met the inclusion criteria. Original studies with 356,297 participants with an average follow-up of 8.6 years (ranging from 2 to 20 years) were included in this study. The pooled RRs of tooth loss on dementia and cognitive decline were 1.15 (95% CI: 1.10-1.20; P < 0.01, I ² = 67.4%) and 1.20 (95% CI: 1.14-1.26; P = 0.04, I ² = 42.3%), respectively. The results of the subgroup analysis showed an increased association between tooth loss and Alzheimer's disease (AD) (RR = 1.12, 95% CI: 1.02-1.23) and vascular dementia (VaD) (RR = 1.25, 95% CI: 1.06-1.47). The results of the subgroup analysis also showed that pooled RRs varied by geographic location, sex, use of dentures, number of teeth or edentulous status, dental assessment, and follow-up duration. None of the Begg's and Egger's tests or funnel plots showed evidence of publication bias.

Discussion

Tooth loss is associated with a significantly increased risk of cognitive decline and dementia, suggesting that adequate natural teeth are important for cognitive function in older adults. The likely mechanisms mostly suggested include nutrition, inflammation, and neural feedback, especially deficiency of several nutrients like vitamin D.

Poor mental health days is associated with higher odds of poor oral health outcomes in the BRFSS 2020

Background

To test the hypothesis that among individuals in the 2020 Behavioral Risk Factor Surveillance System (BRFSS) cross-sectional anonymous health survey in the United States (US), after controlling for confounding, an increasing number of poor mental health (MH) days in the past month is associated with increasing odds of delayed oral health (OH) care utilization and poorer OH outcomes.

Methods

Adjusted logistic regression models were developed with poor MH days as the exposure to examine the association with two dependent variables (DVs): Most recent dental visit longer than one year ago (yes/no), and having lost 6 or more teeth (yes/no).

Results

Approximately one third (32%) reported most recent dental visit more than one year ago, and 17% had lost 6 or more teeth. Those in the second quartile of poor MH days had 11% higher odds of delayed dental visit, and those in the highest quartile had 26% higher odds, compared to the reference group. For having lost 6 or more teeth, compared to the reference group, those in the third quartile had 8% higher odds and those in the fourth quartile had 18% higher odds.

Conclusions

Poor MH days is independently associated with odds of poor OH utilization and OH in the US above and beyond diagnosed mental and physical conditions. Policymakers in the US should expand health insurance plans to include dental insurance, and should increase access to MH care, especially for the aging population, and those with chronic conditions.

Denture wearing status, cardiovascular health profiles, and mortality in edentulous patients: A prospective study with a 27-year follow-up

OBJECTIVES

Life's Simple 7 (LS7) metrics provide insight into improving cardiovascular health (CVH) and help reduce mortality risks. Edentulous older adults have a higher mortality risk than dentulous ones, probably due to worse oral function. It is reported that wearing dentures will decrease the mortality risk factor by improving oral function. This prospective study aimed to investigate if denture wearing could modify the association between CVH profile and mortality risk among edentulous elderly.

METHODS

From the Third National Health and Nutrition Examination Survey (NHANES III), 1,735 edentulous older adults (mean age 69.4 years old) with CVH profiles and data on denture wearing status were selected for this study. CVH profiles according to LS7 metrics were classified into poor, intermediate, or ideal. Denture wearers were defined as those wearing complete dentures in both arches all the time or only when awake. Multivariable Cox proportional-hazards regression was conducted to estimate the association of CVH profiles with all-cause and cardiovascular mortality. Stratified analyses and the testing of interaction terms were used to evaluate the difference between the association in edentulous patients with and without dentures.

RESULTS

A total of 1,420 (81.8%) older adults died during the 27-year follow-up, with 475 (27.6%) cases attributable to heart disease. After controlling for potential confounders, edentulous patients with an ideal CVH (LS7 = 10-14) had a lower mortality risk than those with poor CVH (LS7 = 0-4). Furthermore, we observed an effect modification by denture use (P_interaction = 0.046), with the role of ideal CVH in mitigating mortality among the denture wearers (Hazard Ratio = 0.440 [0.329-0.588]), while no significant association among those without dentures. Similar results were achieved for cardiovascular mortality, but there was no effect modification of denture use (P_interaction = 0.352).

CONCLUSION

In this study, a favorable cardiovascular health profile presents a protective effect on all-cause mortality only among edentulous patients wearing dentures instead of non-wearer.

CLINICAL SIGNIFICANCE

Denture usage could improve oral function (e.g., chewing, smiling, speaking, etc.) and promote general health. Effect modification found in this study indicates having ideal CVH alone cannot substantially reduce mortality risk among edentulous patients. Therefore, health care professionals should keep an eye on the elderly not wearing dentures as they are probably more at risk for adverse health outcomes. It remains unclear if denture wearing has a causal relation with lower mortality risks, and further research is needed.

Periodontal health, cognitive decline, and dementia: A systematic review and meta-analysis of longitudinal studies

BACKGROUND

Emerging evidence indicates that poor periodontal health adversely impacts cognition. This review examined the available longitudinal evidence concerning the effect of poor periodontal health on cognitive decline and dementia.

METHODS

Comprehensive literature search was conducted on five electronic databases for relevant studies published until April 2022. Longitudinal studies having periodontal health as exposure and cognitive decline and/or dementia as outcomes were considered. Random effects pooled estimates and 95% confidence intervals were generated (pooled odds ratio for cognitive decline and hazards ratio for dementia) to assess whether poor periodontal health increases the risk of cognitive decline and dementia. Heterogeneity between studies was estimated by I2 and the quality of available evidence was assessed through quality assessment criteria.

RESULTS

Adopted search strategy produced 2132 studies for cognitive decline and 2023 for dementia, from which 47 studies (24 for cognitive decline and 23 for dementia) were included in this review. Poor periodontal health (reflected by having periodontitis, tooth loss, deep periodontal pockets, or alveolar bone loss) was associated with both cognitive decline (OR = 1.23; 1.05-1.44) and dementia (HR = 1.21; 1.07-1.38). Further analysis, based on measures of periodontal assessment, found tooth loss to independently increase the risk of both cognitive decline (OR = 1.23; 1.09-1.39) and dementia (HR = 1.13; 1.04-1.23). Stratified analysis based on the extent of tooth loss indicated partial tooth loss to be important for cognitive decline (OR = 1.50; 1.02-2.23) and complete tooth loss for dementia (HR = 1.23; 1.05-1.45). However, the overall quality of evidence was low, and associations were at least partly due to reverse causality.

CONCLUSIONS

Poor periodontal health and tooth loss appear to increase the risk of both cognitive decline and dementia. However, the available evidence is limited (e.g., highly heterogenous, lacking robust methodology) to draw firm conclusions. Further well-designed studies involving standardized periodontal and cognitive health assessment and addressing reverse causality are highly warranted.

Association between dentition and frailty and cognitive function in community-dwelling older adults

Objectives

To evaluate dentition status amongst community-dwelling older adults and its association with frailty and cognitive impairment.

Methodology

One thousand forty-seven community-dwelling older adults aged ≥65 years were surveyed in an epidemiologic population-based cohort study in Singapore between April 2015 and August 2016. Data on demographics, dentition status, chronic diseases, activities and instrumental activities on daily-living, cognition (age- and education-specific MMSE cut-offs), frailty (FRAIL scale), perceived health and functional status were collected. Multiple logistic regression was performed to examine the association between dentition, frailty and cognition.

Results

Mean age of participants was 71.2 ± 5.5 years. The prevalence of denture use was 70.7% and edentulism 7.9%. Compared to edentulousness, having teeth was associated with lower odds of cognitive impairment and higher odds of being robust or pre-frail. Denture-wearers compared with edentulous persons were less likely to be male, had higher education level and more likely be robust or pre-frail.

Conclusion and implications

There were significant associations between dentition status, frailty and cognition in our study where those with remining teeth and / or dentures had better overall outcomes. As oral health, frailty and cognitive impairments are all modifiable risk factors for healthy ageing, countries should consider population level screening for oral health, frailty and cognitive impairment.

Tooth loss, dental prostheses use and cognitive performance in older Brazilian adults: The SABE cohort study

AIM

To investigate the within- and between-person longitudinal effects of tooth loss and the use of dentures, clinically assessed by dentists, on cognitive decline in a representative sample of community-dwelling older Brazilian adults.

METHODS

Data came from 1265, 1112 and 1021 individuals aged ≥60 years who participated in the second (2006), third (2010) and fourth (2015) waves, respectively, of the Health, Well-being and Aging study (SABE). Cognitive performance was evaluated with the abbreviated version of the Mini-Mental State Examination (MMSE). The number of natural teeth was classified according to three categories: none, 1-19 and ≥20 teeth. The presence of removable full or partial dentures in each dental arch (yes/no) was recorded. Hybrid regression models, adjusted for sociodemographic, behavior and health-related covariates, were used to estimate the between- and within-person effects of the longitudinal association between cognitive performance and oral health.

RESULTS

Participants with 1-19 and no teeth had, respectively, 1.15 (95% CI 0.65-1.66) and 1.54 (95% CI 0.99-2.09) units lower MMSE score than those with ≥20 teeth. Denture wearers had 1.54 (95% CI 1.13-1.95) units greater MMSE score than non-denture wearers, and those who started wearing dentures during the follow up had 0.83 (95% CI 0.21-1.45) units greater MMSE score after the transition.

CONCLUSION

Our main findings showed that the use of dental prostheses might be a protective factor for cognitive decline. Geriatr Gerontol Int 2021; 21: 1093-1098.

Associations of dietary and drinking water habits with number of natural teeth: a longitudinal study in the Chinese elderly population

Background

The relationship between dietary and drinking water habits and oral health are still unclear. We aimed at evaluating the association of dietary and drinking water habits with number of teeth in the elderly adults.

Methods

We conducted a longitudinal study based on the Chinese Longitudinal Healthy Longevity Survey from 1998 to 2018. The data of dietary and drinking water habits at baseline were collected using a questionnaire. The number of teeth at baseline and follow-up was collected for each subject. We used the linear mixed-effect model to analyze the associations of dietary habits and drinking water sources with tooth number.

Results

Among 19,896 participants at baseline, the mean age of the participants was 83.87 years, with the average number of natural teeth of 9.37, 8.26, 8.38, 8.68, 4.05, 1.92, 1.12, 2.20 for the first to eighth waves of survey. Compared with subjects drinking tap water, 1.036 (95 % CI: -1.206, -0.865), 0.880 (95 % CI: -1.122, -0.637) and 1.331 (95 % CI: -1.715, -0.947) fewer natural teeth were reported for those drinking well, surface water and spring at baseline survey. Compared with participants with rice intake as the staple food, those with wheat intake (β = -0.684; 95 % CI: -0.865, -0.503) tended to have fewer natural teeth. Compared with participants with fresh fruit intake almost every day, those with quite often intake of fresh fruit tended to have fewer teeth with a significant dose-response trend (P_trend <0.001). Similar decreased trend for number of teeth was also indicated for increased frequency of vegetable intake (P_trend <0.001). Fewer number of teeth was found for subjects with less frequency of meat and fish intakes.

Conclusions

The study suggested that drinking well, surface water, and spring, intakes of wheat as staple food, as well as less frequency of fresh fruit, vegetable, meat and fish intakes were associated with significantly fewer number of teeth in the Chinese elderly population.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-021-02473-7.

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

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.