Oral health conditions and frailty in Mexican community-dwelling elderly: a cross sectional analysis

The mouth and its associated structures participate actively in protective and biological functions, and are essential for social activities [1‐3]. The aging people experience a wide variety of oral health problems, such as loss of teeth, edentulism, periodontitis, coronal and root caries, oral mucosal lesions, utilization of nonfunctional dental prostheses (either partial or complete), xerostomia, and chewing problems, among others [4‐8]. These problems begin earlier in life and can promote a decline in general health because reduced nutrient intake, pain, and low quality of life [4, 9‐16].

Dental problems in the elderly are associated with modifications in food selection, changes in nutrient intake [6, 7, 10, 13, 17, 18], chronic conditions such as diabetes [19], and with cardiovascular problems [20‐22]. Oral health problems can be considered chronic diseases because their prevalence and duration; besides, risk factors are common with those of other chronic diseases, such as diabetes or cardiovascular problems [2, 6, 13, 23‐25].

Frailty syndrome is characterized by decreased resilience and physiological reserves, and is generally associated with an increased risk for disability, dependence, falls, hospitalization, and death [26‐29]. Frailty results from excessive demands imposed on a system with a diminished capacity [30, 31]; its prevalence ranges from 3–30% in people ≥65 years old [26, 30, 32, 33].

To explain the approaches relating oral health status and the use of dental services with frailty; it is possible to build a four elements model. The first element is related to therapeutic decisions and the use of dental services, the second is focused on the functional ability of the mouth, the third one refers to the psychosocial process of the subject, and the fourth will focus on the cellular and physiological phenomena related with the inflammatory response. These components emerge from the deterioration of oral health due to either caries or periodontal disease, which can lead to the need for dental care [1‐4], which may be used or not by the subjects leading to different outcomes affecting functionality and quality of life. Moreover, the first and fourth elements could also participate in both ways, periodontal inflammatory processes contribute to an increase in the levels of local and systemic inflammatory mediators and the increment of inflammation due to metabolic alterations contributes to the development or increased severity of periodontal disease, on the other hand, the reduction of mobility and development of disability or dependence consequence of frailty will affect the utilization of dental services because of problems of accessibility; this situation could contribute to the continuous deterioration of oral health (Figure 1).

It has been reported that the use of complete dentures and reports of chewing problems and loss of teeth are associated with fatigue (a component of frailty) and mortality in the elderly [34, 35]. However, associations between other oral health conditions and frailty have not been explored.

The aim of our baseline data analysis was to determine the association between frailty and the presence of oral health conditions such as edentulism, number of teeth present, utilization and/or functionality of removable partial dentures (RPD) or complete dentures (CD), severe periodontitis, xerostomia, self-reported chewing problems, self-perception of oral health, and utilization of dental services during the previous year. The results were adjusted by gender, age, years of education, smoking status, history of myocardial infarction, previous stroke, hypertension, diabetes, osteoporosis, arthritis, urinary incontinence, falls, hospitalization, and number of drugs.

We tested the hypothesis that poor oral health conditions are associated with an increased probability of frailty in community-dwelling elderly.

The study sample is a subset of the participants of the Mexican Study of Nutritional and Psychosocial Markers of Frailty (the Coyoacan cohort), a prospective cohort study aiming to evaluate the nutritional and psychosocial determinants of frailty among Mexican community-dwelling elderly, conducted by the Department of Geriatrics of the National Institute of Medical Sciences and Nutrition “Salvador Zubirán” (INCMNSZ) of Mexico in collaboration with the National Institute of Public Health (INSP), the Department of Dental Public Health, the Graduate Studies and Research Division of the Dental School at the National Autonomous University of Mexico (UNAM), the Department of Health of the Government of the Federal District of Mexico, and the National Institute of Geriatrics of the Mexican Ministry of Health.

The overall mean age was 77.9 ± 6.3 years; 53.2% (n = 372) were women; 67.6% (n = 221) of men were married, and 51.3% (n = 191) of women were widowed; men had completed more years of schooling (mean = 7.9 ± 5.8) than women (mean = 6.7 ± 5.0; p < 0.01).

The prevalence of frailty was 15.0% (n = 105), with 12.2% (n = 40) prevalence among men and 17.5% (n = 65) prevalence among women.

The mean number of teeth present was 10.7 ± 9.2, with a 23.5% (n = 197) prevalence of edentulism; 9.1% of the participants (n = 76) had ≥25 teeth. The utilization of RPD and/or CD among edentate or partially dentate subjects was 61.9% (n = 472); of these, 67.6% (n = 319) of RPDs and CDs were not functional. The prevalence of severe periodontitis was 8.9% (n = 57) among subjects who were partially or completely dentate (Table 1).

Among all subjects, 23.8% suffered from cognitive impairment; 19% suffered from urinary incontinence; 8.4% had suffered ≥3 falls in the previous year; 49.8% reported former or current smoking; 11.1% were hospitalized during the previous year; 8.4% had suffered myocardial infarction; 3.9% had suffered a stroke; 55.3% had hypertension; 21.5% were diabetics; 13.6% reported having osteoporosis; 15.6% had arthritis; and the mean number of drugs taken daily was 2.75 ± 2.2.

No significant differences were found in the prevalence of frailty based on number of falls in the previous year (p = 0.11), smoking status (p = 0.35), hypertension (p = 0.10), diabetes (p = 0.80), severe periodontitis (p = 0.29), utilization of removable or complete dentures (p = 0.19), or functionality of partial or complete dentures (p = 0.37) (Table 2).

The analysis also showed that frail participants were older (mean = 81.6 ± 6.6, p < 0.001), and that participants were more likely to be frail if they scored ≤18 on the MMSE (OR = 2.6; 95% CI 1.5–4.2), reported urinary incontinence (OR = 3.5; 95% CI 2.2–5.6), were hospitalized during the last year (OR = 3.2; 95% CI 1.8–5.4), had a history of myocardial infarction (OR = 2.1; 95% CI 1.1–3.9), had suffered a stroke (OR = 3.7; 95% CI 1.5–9.1), suffered from osteoporosis (OR = 2.6; 95% CI 1.5–4.3), suffered from arthritis (OR = 2.0; 95% CI 1.2–3.3), did not use dental services the previous year (OR = 1.7; 95% CI 1.1–2.5), reported xerostomia (OR = 1.6; 95% CI 1.0–2.4), or reported chewing problems (OR = 2.0; 95% CI 1.3–3.0). Further, frail subjects used a higher number of drugs on a daily basis (mean = 4.1 ± 2.8, p < 0.001) and had a lower mean number of teeth (mean = 8.3 ± 8.6, p < 0.001) than non-frail subjects. The prevalence of frailty was higher among those who perceived that their oral health was worse than others of the same age (25%) (p = 0.006) and among edentulous subjects (23.5%) (p = 0.003). (Table 2)

We observed, using a representative sample of people ≥70 years old who resided in one district of Mexico City, that the perception of having worse oral health than others of the same age and the failure to utilize dental services were associated with an increased probability of being frail. This is the first study that has explored frailty in the Mexican elderly and included oral health components. The multidisciplinary approach of this project allows us to explore the relationships between frailty and many other variables [32].

There are few previous data on the association between oral health and some components of the frailty syndrome, but not with the frailty syndrome overall [34, 35].

There was an association between not using dental services during the past year and a higher probability of being frail and (OR = 2.1, 95% CI 1.2–3.8); Overall, the utilization of dental services among the elderly is lower [43] (49% in this study) than the utilization of medical services (85%) [44]. According to Kiyak [45], elderly people who believe that declining health is a part of aging and that recovery is not possible, reflect that attitude by not utilizing dental services. Taking this into account, the observed lack of utilization of dental services might also reflect compromised general health, which in turn may be correlated with frailty.

Another possible explanation could be constriction of life space, which has been recognized as a risk factor for frailty [46]. Constriction of life space is attributable to loss of mobility, weakness, and slowness, which result in difficulties with moving and travelling independently to receive dental care. This, in addition to low expectations about oral health, could contribute to this population’s failure to utilize dental services.

The probability of being frail was 2.2 times higher for those who considered their oral health worse than others of the same age; this could be explained by the positive association between oral health and general health [3, 6]. We can assume that a bad perception of oral health reflects declining general health.

Oral health is recognized as a component of general health [3], and it is unusual for people to identify oral health conditions as their only health problems when those issues are so advanced that they affect feeding ability, speaking, chewing, physical appearance, and social life, frequently producing pain and favoring depression [47‐50]. Also, when oral health is poor, inflammation markers are increased, which in turn can alter the metabolism of other organs; even though self-perception of oral health is subjective, it can represent a risk indicator for frailty.

Oral health expectations among the elderly could also be influenced by age, education level, socioeconomic situation, and social support [51], variables that have been associated with frailty.

Even though the presence of severe periodontitis did not surpass the threshold of statistical significance as a predictor of frailty (OR = 3.9, 95% CI 0.98–15.6) in the final logistic model, the physiological process related to the development of periodontal infection could be related to the development of frailty. It has been shown that severe periodontitis is linked to energy imbalance, which in the elderly has been associated with loss of mobility and strength alterations that end with the development of frailty syndrome. It has been shown that higher concentrations of pro-inflammatory cytokines could favor the altered inflammation state observed in frailty syndrome [29, 52, 53]. It is important to point out that periodontitis requires the presence of teeth; in the logistic regression model, we included edentulous subjects in the “no severe periodontitis” group in order to preserve the sample size, but in a later analysis considering only completely or partially dentate (1–32 teeth) subjects, we observed that those with severe periodontitis have 5.3 times the risk for frailty than those without severe periodontitis (95% CI 1.3–22.2). The participation of severe periodontitis in the development of frailty should be explored in the longitudinal analysis.

Other studies have explored the relationship between dental variables and frailty: Avlund et al. [34] reported that having few teeth increases the risk of fatigue in the elderly; also, Semba et al. [35] reported that frail edentate women with complete dentures who complain about chewing problems have higher mortality rates than frail edentulous women who reported no chewing problems. In this study, we did not find an association between the number of teeth and frailty or between chewing problems and frailty; we must consider that in our sample the prevalence of overweight and obesity was 75%, which could dissipate the effect of tooth loss on frailty among the elderly in Coyoacán. On the other hand, elderly people living in Mexico who have few (1-9) teeth and who wear nonfunctional dental prostheses tend to modify their diets, increasing the consumption of low-nutrient foods. This could explain the fact that many of them are overweight and obese, and it could hide the effects of having few or no teeth on the risk of frailty and mortality [34, 35]. It is important to mention that obese sarcopenia could be a confounding factor in the evaluation of frailty [54].

Several researchers have measured dental variables with physical activity. Takata and cols., explored the association between chewing ability and number of teeth with physical activity using hand grip strength, leg extensor strength, leg extensor power, stepping rate, and one-leg standing time as indicators. These are specific measurements of physical activity, one of the components of frailty. However, comparisons with our study are difficult because we used The Physical Activity Scale for the Elderly (PASE) [38], an instrument designed for screening for low physical activity in the elderly. Also, we measured frailty as a whole and not considering the components individually. Even when the associations of chewing ability and number of teeth with frailty were statistically significant in the univariate model, in the logistic regression model the associations disappeared. Similarly, Takata did not find association with number of teeth; but when comparing the number of chewable foods they observed an increase in isokinetic leg extension power and in one-leg standing time, association that we did not observed with frailty. The type of measurement for physical activity used in this study might be a limitation, it is worth considering in future studies a more detailed measurement [55].

It is important to mention that this study included clinical evaluation of dental variables as well as questions about self-perception of oral health and self-reports of utilization of dental services during the last year. None of these variables has been considered in other reports on frailty. However, the inclusion of several oral health conditions represents a challenge because of the mutually exclusive characteristics of some dental variables (e.g., periodontitis and edentulism).

We recognize the need for a global oral health indicator, and we question, “What would be an optimal oral health indicator in the elderly, and how can we measure it?” A global oral health indicator should be able to classify those people who are properly rehabilitated (using functional dental prosthesis) and have no periodontal problems. It should also be able to classify those with complex oral conditions (e.g., nonfunctional dental prosthesis and periodontal disease in the remaining teeth, or presence of remaining roots), which could increase the risk of developing other chronic conditions, favoring energy imbalance and creating clinical and therapeutic challenges.

The covariates measured in this analysis were consistent with those measured in previous reports; we observed a higher risk of frailty among those who had been hospitalized during the previous year, those who consumed higher number of drugs on a daily basis, those who reported incontinence, and those who had a history of myocardial infarction [26, 27, 51, 56‐58].

Low utilization of dental services and poor self-perception of oral health could be considered possible risk markers for frailty syndrome. The role of periodontitis and other oral clinical variables in frailty should be explored in longitudinal studies. The comprehensive geriatric assessment should include a question about self-perception of oral health, because this question reflects both objective and subjective aspects of health and is associated with a higher probability of being frail. The inclusion of a question about utilization of dental services during the previous year on the comprehensive geriatric assessment should also be considered, because the answer to this question is related to other factors that can promote the development of frailty.