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.

The validity of self-reported number of teeth and edentulousness among Norwegian older adults, the HUNT Study.

BACKGROUND: Number of teeth is an established indicator of oral health and is commonly self-reported in epidemiological studies due to the costly and labor-intensive nature of clinical examinations. Although previous studies have found self-reported number of teeth to be a reasonably accurate measure, its accuracy among older adults ≥ 70 years is less explored. The aim of this study was to assess the validity of self-reported number of teeth and edentulousness in older adults and to investigate factors that may affect the accuracy of self-reports. METHODS: This study included two different samples of older adults ≥ 70 years drawn from the fourth wave of the Trøndelag Health Study (the HUNT Study), Norway. Sample 1 (n = 586) was used to evaluate the validity of self-reported number of teeth and sample 2 (n = 518) was used to evaluate self-reported edentulousness. Information on number of teeth and background variables (education, smoking, cognitive function, and self-perceived general and oral health) were self-reported in questionnaires, while clinical oral health examinations assessed number of teeth, number of teeth restored or replaced by fixed prosthodontics and edentulousness. Spearman and Pearson correlation coefficients, Bland-Altman plot, chi-square test and kappa statistics were used to assess the agreement between self-reported and clinically recorded number of teeth. RESULTS: The mean difference between self-reported and clinically recorded number of teeth was low (- 0.22 teeth), and more than 70% of the participants reported their number of teeth within an error of two teeth. Correlations between self-reports and clinical examinations were high for the total sample (0.86 (Spearman) and 0.91 (Pearson)). However, a lower correlation was found among participants with dementia (0.74 (Spearman) and 0.85 (Pearson)), participants having ≥ 20 teeth (0.76 (Spearman) and 0.67 (Pearson)), and participants with ≥ 5 teeth restored or replaced by fixed prosthodontics (0.75 (Spearman) and 0.77 (Pearson)). Self-reports of having teeth or being edentulous were correct in 96.3% of the cases (kappa value 0.93, p value < 0.001). CONCLUSIONS: Among older Norwegian adults, self-reported number of teeth agreed closely with clinical tooth counts and nearly all the edentulous participants correctly reported having no teeth.

Validity of self-reported tooth counts and masticatory status study of a Japanese adult population.

Self-reported measures of oral health are often used to assess oral health in populations or groups, but their validity or reliability needs repeated confirmation. The objective of this cross-sectional study was to evaluate the validity of self-reported tooth counts and masticatory status, using data obtained from a sample of Japanese adults. A total of 2356 adults aged 40 to 75 years participated in a questionnaire survey and a clinical oral examination from 2013 through 2016. Self-reported measures were compared with clinically measured values. For tooth counts, mean clinical and self-reported tooth counts in all participants were 23.68 and 23.78 teeth, and no significant difference was detected. Spearman's, Pearson's and intra-class correlation coefficients between clinical and self-reported tooth counts were 0.771, 0.845 and 0.843, respectively. According to the Bland-Altman analysis, the mean difference between clinical and self-reported tooth counts was -0.098 (95% CI: -0.242, 0.047). The upper limit of agreement was 6.919 (95% CI: 6.669, 7.169), and the lower limit of agreement was -7.115 (95% CI: -7.365, -6.865). No significant fixed or proportional bias was observed. For masticatory status, the crude or age- and gender-adjusted mean numbers of total teeth, posterior teeth and 3 kinds of functional tooth units significantly decreased with the deterioration of masticatory status. This study indicated that self-reports were within an acceptable range of clinical measures. Therefore, self-reports were considered valid alternatives to clinical measures to estimate tooth counts and masticatory status in a current Japanese adult population.

Association between missing tooth count and mortality: A systematic review.

PURPOSE: The purpose of this review was to analyze existing literature on the relationship between tooth count and mortality by evaluating the findings in the context of methodological variations. We aimed at addressing the question of whether preserving natural teeth can impact mortality. STUDY SELECTION: PubMed, Web of Science and CINAHL databases were systematically searched using various combinations of related and synonymous keywords for "tooth count" and "mortality". The references of included articles were also evaluated for inclusion. Overall 49 studies found to be eligible were critically evaluated and their key findings were summarized. RESULTS: Studies were conducted in various continents and differed substantially in regards to their sample size, population, methodology, the definition of the tooth count variable, the confounders as well as the mediators accounted for in the analysis. Follow-up period ranged from 1 to 56 years. CONCLUSIONS: Although high variability in the studies precludes a definite conclusion about the relationship between number of teeth and mortality, the overall finding from this review is that reduced tooth count is associated with higher mortality. However the impact of factors such as smoking, health-care access, baseline co-morbidity and risk profile, dental and periodontal health, the presence of dental prosthesis as well as socio-economic status, in mediating whole or part of the association cannot be overlooked and needs further investigation using more standard methodologies. Any differences in males vs. females, as well as among different age groups, will also need further consideration in the future studies.