Abstract
Background
Aging populations worldwide face a substantial burden of psychological distress that affects their quality of life and overall health. Oral health is associated with psychological distress; however, the effect of changes in the number of teeth on psychological distress remains unknown. This study aimed to evaluate the association of changes in the number of teeth with the development of psychological distress among community‐dwelling older adults in Taipei City.
Methods
From 2005 to 2013, 62,119 community‐dwelling individuals aged 65 years and older participated in the physical examination program in Taipei. We collected data on the number of teeth during each examination. Psychological distress was defined as a score of ≥6 on the Brief Symptoms Rating Scale. A generalized estimating equation (GEE) model was used to examine the longitudinal relationship between changes in the number of teeth and the development of psychological distress.
Results
The participants lost an average of 6.6 teeth during the follow‐up, with 9.9% of oral examination records showing the loss of ≥5 teeth compared with the previous examination. After GEE analysis with adjustment for multiple covariates, participants were at higher risk of developing psychological distress if they lost 1–4 teeth, 5–9 teeth, or ≥10 teeth compared to that at their previous oral examination. Subgroup analysis revealed that participants with ≥20 teeth at baseline and those who used dentures to compensate for the tooth loss had a lower risk of developing psychological distress than those who experienced tooth loss and did not use dentures.
Conclusion
A rapid decrease in the number of teeth is associated with an increased risk of psychological distress in older adults. Regular dental checkups, nutritional counseling, and the use of dentures are critical in mitigating the adverse psychological effects of the tooth loss.
Keywords: dentures, number of teeth, older adult, psychological distress
INTRODUCTION
The aging population is growing worldwide, with one‐sixth of the world population expected to be aged ≥60 years by 2030. More than 14% of older adults suffer from psychological distress, with depression and anxiety being the most common conditions. 1 Studies have found that depression increases the risk of disease, reduces quality of life, and heightens the risk of suicide.2, 3, 4
Previous studies have revealed a bidirectional relationship between poor oral health, including tooth loss, and psychological distress, with each negatively affecting the other. Previous studies have shown that participants with serious mental illnesses, such as schizophrenia and bipolar disorder, have a lower oral health self‐care behaviors and exhibit increased number of decayed, missing, or filled teeth.5, 6, 7 However, these meta‐analyses indicate that, owing to the limitations of their respective studies, more research is needed to explore the reasons for poor oral health in patients with severe mental illness; hence, the direction of causality remains unknown.
A lower number of teeth, which is a vital indicator of the oral health status, may be associated with higher psychological distress levels in older adults. Previous studies have indicated that a low number of teeth is associated with various mental health issues, including deficient sleep, 8 anxiety, 9 and depression.10, 11, 12, 13 Additionally, immune‐inflammatory pathways may play an important role in this association. A recent systematic review highlighted the connection between periodontal disease and depression, emphasizing the involvement of systemic inflammation. 14 Nutritional factors may explain the association between fewer teeth and mental disorders, since maintaining oral health or having more teeth affects food choices and nutritional status in older adults.15, 16 Lack of specific nutrients and poor dietary quality are linked to psychological distress.17, 18 Another possible reason is that the number of teeth is associated with social participation. For example, poor oral health, including fewer remaining teeth, exacerbates social withdrawal and isolation, leading to low self‐esteem and a decline in functional capacity.19, 20 However, existing literature is scarce, with two studies that have used self‐administered questionnaires to obtain the number of teeth,10, 13 and only one that included the use of dentures in the statistical model. 11 Furthermore, this association has been inconsistent in other studies. 21 Psychological distress, such as depression, anxiety, hostility, and somatization, 22 may be impacted by a lower number of teeth, but this relationship remains unclear. Moreover, no studies have investigated the association between changes in the number of teeth and psychological distress in older adults during the follow‐up period.
Older adults who are edentulous or partially edentulous may choose to use removable dentures or implants to restore their teeth. Although dentures can provide functional restoration with minimal invasiveness, studies have found that tooth loss is associated with significant psychological distress even when dentures are used successfully.23, 24 The possible reason is that the period of adaptation to dentures involves suffering and requires psychological efforts to be successful. 25 However, these studies were cross‐sectional or obtained information through questionnaires; therefore, the effectiveness of dentures in reducing the psychological distress associated with missing teeth requires further investigation.
This novel 9‐year longitudinal prospective cohort study aimed to evaluate the effect of changes in the number of teeth on the subsequent development of psychological distress among community‐dwelling older adults in Taipei City.
METHODS
Study population
The data for this 9‐year longitudinal prospective cohort study was sourced from the Taipei City Elderly Health Examination Database. Participants were enrolled in a complimentary annual physical examination program for older adults provided by the Taipei City government from May 1, 2005 to December 31, 2013. The cohort consisted of 119,572 participants aged 65 years. These individuals underwent routine physical examinations voluntarily and were encouraged to participate annually. The assessments included standardized medical examinations, oral examinations, and self‐administered questionnaires covering various health‐related topics, including screening for psychological distress. Overall, 62,119 participants were included in the analysis after excluding those with only one examination record (N = 38,650) and those with mental illnesses (n = 6713) or abnormal Brief Symptoms Rating Scale (BSRS‐5) scores on psychological distress (n = 12,090) at baseline. A flowchart illustrates a sample selection process (Figure 1). Mental illnesses were identified when participants indicated a personal history of mental illness or medication history of psychotropic or sleeping pills on the baseline self‐report questionnaire. Participant identification data were encrypted before analysis. The study design adhered to the principles of the Declaration of Helsinki and was approved by the Institutional Review Board of Taipei City Hospital (IRB No. TCHIRB‐11303014‐W).
FIGURE 1.
Flowchart of the patient selection process.
Number of teeth
The oral health of the study participants, including the number of remaining teeth and use of dentures (yes or no, including removable and fixed dentures), was examined by a qualified dentist. Based on previous research, the number of teeth was defined as the total number of remaining teeth and divided into four groups: no teeth, 1–9 teeth, 10–19 teeth, and ≥20 teeth. 10 This study used records from each oral examination from baseline to the end. Moreover, to observe the impact of changes in the number of teeth on psychological distress, we compared the number of teeth in each participant's follow‐up dental examination with that in their previous examination. In each follow‐up, if there was no decrease in the number of teeth compared to the previous examination, it was used as the reference; a decrease of 1–4 teeth was coded as 1; decrease of 5–9 teeth as 2; and decrease of ≥10 teeth as 3. 26 This approach should evaluate the influence of losing more teeth on psychological distress.
Psychological distress
Psychological distress was assessed during each physical examination using the BSRS‐5 developed by Lee et al. 27 Respondents were asked to select responses indicating their mental health state during the previous week. The scale contains five self‐reported items: (1) having trouble falling asleep (insomnia), (2) feeling tense or keyed up (anxiety), (3) feeling easily annoyed or irritated (hostility), (4) feeling low in mood (a sign of depression), and (5) feeling inferior to others (inferiority). The total score of the BSRS‐5 is 20 points, with 0–4 points for each item (0, not present; 1, slight; 2, moderate; 3, severe; and 4, extremely severe). The cutoff point for the early detection of psychological distress using the BSRS‐5 was ≥6 points. Scores of ≥6 or higher were categorized as psychological distress, indicating the possibility of a psychiatric condition and warranting further assessment, whereas scores of ≤5 as normal. The BSRS‐5 is commonly used in Taiwan for rapid psychological distress screening with high validity and reliability in the general community population.27, 28, 29, 30
Covariates
As covariates, age, sex, health examination visits, educational attainment (≤6 years, 7–9 years, or ≥10 years), low‐income household, marital status (married, not married), co‐residence (living alone or with other), body mass index (BMI, underweight: <18.5, normal weight: 18.5–24.0, overweight: 24–27, and obesity: ≥27 kg/m2), 31 periodontitis (diagnosed by dentist during each oral examination), medication history for chronic diseases (hypertension, diabetes, hyperlipidemia, and heart disease; yes or no), smoking (current smoker, current nonsmoker), drinking (occasional or frequent, never), and exercise (20+ min per week; yes or no) were collected using a self‐administered questionnaire. Among these covariates, sex, marital status, educational attainment, co‐residence, and low‐income household were recorded at baseline, whereas all other covariates were treated as time‐varying and updated at each follow‐up examination. In Taiwan, older adults in our study cohort received their education under a system where compulsory education was only up to primary school (6 years). Education beyond this level required entrance examinations, making 7–9 years (junior high school) and ≥10 years (senior high school and above) significant educational milestones. Furthermore, low‐income households in Taiwan are defined as those with an average monthly disposable income per person that is ≤ 60% of the minimum standard of living expense in Taiwan (≤19,013 New Taiwan Dollars [NTD]). The qualifications of low‐income households are reviewed annually by the Taipei City Government. 32
Statistical analyses
The baseline characteristics of the participants with different numbers of teeth were compared using the Kruskal–Wallis test for continuous variables and the chi‐square test for categorical variables, as appropriate. Generalized estimating equations (GEEs) were used to examine the longitudinal relationships between changes in the number of teeth during follow‐up and the subsequent development of psychological distress, after adjusting for age, sex, health examination visits, years of education, low‐income household, marital status, living alone, smoking, drinking, exercise, baseline BSRS‐5 score, BMI category, hypertension, heart disease, diabetes, and hyperlipidemia. The GEEs method allows for the analysis of cumulative longitudinal data, controlling for repeated observations and follow‐up years within participants. It enables the identification of general patterns over the entire study period and has been used in various longitudinal studies with repeated measurements.11, 33, 34 Our primary analysis used categorical variables for psychological distress and the number of remaining teeth in the GEEs model. In the sensitivity analysis, we treated psychological distress and the number of remaining teeth as continuous variables in the same GEEs model to check for consistency in the results. We used a logit link function in the GEEs for our analysis. Odds ratios (OR) with 95% confidence intervals (CI) were used to determine the strength and direction of associations. All data management and analyses were performed using the SAS software (version 9.4; SAS Institute, Cary, NC, USA). The level of significance was set at a two‐tailed p‐value <0.05.
RESULTS
Table 1 presents the basic characteristics and demographics of all participants (N = 62,119): 53.0% were men, 52.5% had ≥10 years of education, 74.9% were married, 45.4% had normal weight, 56.9% had periodontitis, 91.8% were current non‐smokers, 80.2% never drank alcohol, and 91.9% exercised for more than 20 min per week at baseline. There were 49,517 participants with the number of teeth ≥20 (79.7%), whereas 6315 (10.2%) participants had 10–19 teeth, 3358 (5.4%) had 1–9 teeth, and 2929 (4.7%) had no teeth. Participants with fewer teeth were more likely to be older, have lower educational attainment, have a lower household income, be unmarried, have a higher history of medication use, be current smokers, and not exercise than those with more teeth.
TABLE 1.
Baseline characteristics and demographics of the study population (N = 62,119).
| Characteristics, n (%) | Total | ≥20 (n = 49,517) | 10–19 (n = 6315) | 1–9 (n = 3358) | No teeth (n = 2929) | p value |
|---|---|---|---|---|---|---|
| Age, years (mean ± SD) | 72.6 ± 6.6 | 71.9 ± 6.3 | 74.6 ± 6.5 | 76.0 ± 6.7 | 76.2 ± 6.8 | <0.001 |
| Sex | ||||||
| Male | 32,895 (53.0) | 26,115 (52.7) | 3483 (55.2) | 1760 (52.4) | 1537 (52.5) | 0.003 |
| Female | 29,224 (47.0) | 23,402 (47.3) | 2832 (44.8) | 1598 (47.6) | 1392 (47.5) | |
| Health examination visits (mean ± SD) | 4.4 ± 2.2 | 4.1 ± 2.2 | 4.4 ± 2.2 | 4.5 ± 2.3 | 5.2 ± 2.3 | <0.001 |
| Educational attainment (years), missing data = 1167 | ||||||
| ≤6 | 20,370 (33.4) | 15,357 (31.6) | 2368 (38.5) | 1395 (42.7) | 1250 (43.8) | <0.001 |
| 7–9 | 8567 (14.1) | 6835 (14.0) | 901 (14.6) | 451 (13.8) | 380 (13.3) | |
| ≥10 | 32,015 (52.5) | 26,489 (54.4) | 2884 (46.9) | 1419 (43.5) | 1223 (42.9) | |
| Low‐income household | 2914 (4.7) | 2015 (4.1) | 413 (6.5) | 261 (7.8) | 225 (7.7) | <0.001 |
| Marital status, missing data = 201 | ||||||
| Married | 46,393 (74.9) | 37,697 (76.4) | 4494 (71.4) | 2275 (67.9) | 1927 (66.1) | <0.001 |
| Not married | 15,525 (25.1) | 11,659 (23.6) | 1803 (28.6) | 1073 (32.1) | 990 (33.9) | |
| Living alone | 3626 (5.8) | 2784 (5.6) | 412 (6.5) | 240 (7.2) | 190 (6.5) | <0.001 |
| BMI category, missing data = 578 | ||||||
| Underweight | 2045 (3.3) | 1467 (3.0) | 247 (4.0) | 185 (5.6) | 146 (5.1) | <0.001 |
| Normal weight | 27,950 (45.4) | 22,307 (45.4) | 2806 (45.1) | 1527 (46.3) | 1310 (45.4) | |
| Overweight | 20,155 (32.8) | 16,305 (33.2) | 1957 (31.4) | 986 (29.9) | 907 (31.5) | |
| Obesity | 11,391 (18.5) | 9057 (18.4) | 1212 (19.5) | 602 (18.2) | 520 (18.0) | |
| Periodontitis | 35,346 (56.9) | 28,463 (57.5) | 4195 (66.4) | 1669 (49.7) | 1019 (34.8) | <0.001 |
| Medication history | ||||||
| Hypertension | 22,577 (36.3) | 17,779 (35.9) | 2367 (37.5) | 1308 (38.9) | 1123 (38.3) | <0.001 |
| Diabetes | 6655 (10.7) | 4926 (9.9) | 829 (13.1) | 467 (13.9) | 433 (14.8) | <0.001 |
| Hyperlipidemia | 3413 (5.5) | 2819 (5.7) | 300 (4.8) | 158 (4.7) | 136 (4.6) | <0.001 |
| Heart disease | 8864 (14.3) | 6816 (13.8) | 990 (15.7) | 560 (16.7) | 498 (17.0) | <0.001 |
| Current smoker, missing data = 144 | 5053 (8.2) | 3728 (7.6) | 650 (10.3) | 350 (10.5) | 325 (11.1) | <0.001 |
| Occasional or frequent drinking, missing data = 152 | 12,279 (19.8) | 10,172 (20.6) | 1126 (17.9) | 509 (15.2) | 472 (16.1) | <0.001 |
| Exercise (20+ minutes per week), missing data = 390 | 56,712 (91.9) | 45,502 (92.5) | 5711 (91.0) | 2944 (88.4) | 2555 (87.9) | <0.001 |
| With use of denture | 13,430 (21.6) | 4560 (9.2) | 3846 (60.9) | 2506 (74.6) | 2518 (86.0) | <0.001 |
Abbreviations: BMI, body mass index; married, married living together, cohabiting; unmarried, unmarried, divorced, widowed, married living separately.
The changes in the number of teeth during the follow‐up period are indicated in Table 2. The mean duration was 5.4 years. During the follow‐up period, participants lost an average of 6.6 teeth of their teeth, and the number of those with no teeth increased by 8348 (13.5%). Among a total of 272,416 oral examination records from 62,119 participants, there were 30,761 (11.3%) records with a decrease of 1–4 teeth, 12,865 (4.7%) with a decrease of 5–9 teeth, and 14,169 (5.2%) by ≥10.
TABLE 2.
Changes in the number of teeth during the follow‐up period from May 1, 2005 to December 31, 2013.
| Variable, n (%) | Baseline | Last examination |
|---|---|---|
| Follow‐up duration, years (mean ± SD) | 5.4 ± 2.4 | |
| Number of teeth (mean ± SD, N = 62,119) | 25.0 ± 9.2 | 18.4 ± 11.6 |
| ≥20 | 49,517 (79.7) | 36,197 (58.3) |
| 10–19 | 6315 (10.2) | 8618 (13.9) |
| 1–9 | 3358 (5.4) | 6027 (9.7) |
| No teeth | 2929 (4.7) | 11,277 (18.2) |
| Changes in the number of teeth compared to the previous examination (Total examinations: 272,416) | ||
| No loss | 214,621 (78.8) | |
| Lost 1–4 teeth | 30,761 (11.3) | |
| Lost 5–9 teeth | 12,865 (4.7) | |
| Lost ≥10 teeth | 14,169 (5.2) | |
Table 3 reveals the association between the number of teeth and the development of psychological distress analyzed using multivariable‐adjusted GEEs. After adjusting for multiple confounding factors, participants who were edentulous had a significantly higher risk of developing psychological distress than participants who had ≥20 teeth (OR: 1.23; 95% CI: 1.12–1.34). However, participants who used dentures showed a lower risk of developing psychological distress than those who did not use dentures (OR:0.85, 95% CI:0.79–0.91). Furthermore, participants were at high risk of developing psychological distress if they lost 1–4 teeth (OR: 1.42, 95% CI: 1.34–1.51), 5–9 teeth (OR: 1.55, 95% CI: 1.41–1.69), or ≥ 10 teeth (OR: 1.70, 95% CI: 1.55–1.85) compared to their previous oral examination.
TABLE 3.
Association of number of teeth and psychological distress by multivariable adjusted generalized estimating equation analysis.
| Model 1 a | Model 2 b | Model 3 c | ||||
|---|---|---|---|---|---|---|
| Variable | OR | 95% CI | OR | 95% CI | OR | 95% CI |
| Number of teeth | ||||||
| ≥20 | Reference | Reference | Reference | |||
| 10–19 | 1.23 | 1.15–1.33 | 1.10 | 1.01–1.19 | 1.09 | 1.00–1.18 |
| 1–9 | 1.24 | 1.13–1.35 | 1.12 | 1.01–1.23 | 1.11 | 1.01–1.23 |
| No teeth | 1.51 | 1.39–1.64 | 1.21 | 1.10–1.32 | 1.23 | 1.12–1.34 |
| With use of denture | ||||||
| No | Reference | Reference | Reference | |||
| Yes | 0.84 | 0.79–0.89 | 0.85 | 0.79–0.91 | 0.85 | 0.79–0.91 |
| Changes in the number of teeth compared to the previous examination | ||||||
| No loss | Reference | Reference | Reference | |||
| Lost 1–4 teeth | 1.40 | 1.32–1.47 | 1.43 | 1.34–1.52 | 1.42 | 1.34–1.51 |
| Lost 5–9 teeth | 1.44 | 1.33–1.56 | 1.56 | 1.43–1.71 | 1.55 | 1.41–1.69 |
| Lost ≥10 teeth | 1.42 | 1.32–1.53 | 1.71 | 1.56–1.86 | 1.70 | 1.55–1.85 |
Abbreviations: CI, confidence interval; GEE, generalized estimating equation; OR, odds ratio.
Model 1 is adjusted for age and sex.
Model 2: Adjusted with age, sex, health examination visits, years of education, low‐income household, marital status, living alone, smoking, drinking, exercise, and baseline Brief Symptoms Rating Scale (BSRS‐5) score.
Model 3: Adjusted with age, sex, health examination visits, years of education, low‐income household, marital status, living alone, smoking, drinking, exercise, baseline BSRS‐5 score, body mass index (BMI) category, periodontitis, hypertension, heart disease, diabetes, and hyperlipidemia.
Figure 2 shows the results of the subgroup analysis of the association between changes in the number of teeth and the development of psychological distress among participants with different numbers of teeth at baseline. After adjusting for multiple confounding factors, participants who had ≥20 teeth (OR: 0.88; 95% CI: 0.82–0.94) at baseline and used dentures showed a lower risk of developing psychological distress compared to those who experienced tooth loss without using dentures; however, this reduced risk was not observed among those with 10–19 teeth (OR: 0.95; 95% CI: 0.78–1.15) or 1–9 teeth (OR: 0.99; 95% CI: 0.69–1.44) at baseline. Furthermore, participants who lost 1–4 teeth had a higher risk of developing psychological distress, whether they had ≥20 teeth (OR: 1.40; 95% CI: 1.30–1.50) or 10–19 teeth (OR: 1.49; 95% CI: 1.22–1.82) at baseline. This risk was increased in those who lost 5–9 teeth (OR: 1.53; 95% CI: 1.38–1.70 for ≥20 teeth; OR: 1.59; 95% CI: 1.24–2.05 for 10–19 teeth). Participants who lost ≥10 teeth (OR: 1.78; 95% CI: 1.61–1.96 for ≥20 teeth; OR: 1.98; 95% CI: 1.63–2.40 for 10–19 teeth) had the highest risk.
FIGURE 2.
Subgroup analysis of the association between changes in the number of teeth and psychological distress among participants with different numbers of teeth at baseline by multivariable‐adjusted generalized estimating equation (GEE) analysis. *Adjusted for age, sex, health examination visits, years of education, low‐income household, marital status, living alone, smoking, drinking, exercise, baseline Brief Symptoms Rating Scale (BSRS‐5) score, body mass index, periodontitis, hypertension, heart disease, diabetes, and hyperlipidemia. aOR, adjusted odds ratio; CI, confidence interval.
In the sensitivity analysis, psychological distress as BSRS‐5 scores and number of remaining teeth were treated as continuous variables in the GEEs model. The results are similar to those presented in Table 3. If the older adults had fewer teeth, they had a higher risk of the increased BSRS‐5 scores (OR: 0.996, 95% CI: 0.995–0.997). Furthermore, participants were at high risk of higher BSRS‐5 scores if they lost 1–4 teeth (OR: 1.04, 95% CI: 1.02–1.06), 5–9 teeth (OR: 1.06, 95% CI: 1.03–1.10), or ≥10 teeth (OR: 1.08, 95% CI: 1.05–1.11) compared to those in their previous oral examination.
DISCUSSION
To the best of our knowledge, this is the first study to explore the longitudinal association of changes in the number of teeth and denture use on the development of psychological distress among community‐dwelling older adults. The results of the present study indicated that older adults who were edentulous at baseline had a significantly higher risk of developing psychological distress than those with 20 or more remaining teeth. Moreover, if participants lost 1–4 teeth, 5–9 teeth, or ≥10 teeth since their previous oral examination, they had a higher risk of developing psychological distress. Furthermore, the use of dentures was associated with a reduced risk of developing psychological distress; however, this effect was not observed when the number of teeth at baseline was less than 20.
This study used the BSRS‐5 as a screening tool for psychological distress, which has been proven to have good sensitivity in identifying psychiatric morbidity. 28 Although existing longitudinal studies on the number of teeth and mental disorders in older adults primarily focused on depression as the outcome, psychological distress encompasses a range of disorders beyond depression, which includes anxiety, hostility, and somatization. 22 Our results are similar to some of the previous findings. For example, Yamamoto et al. observed that edentulous older adults were at a high risk of developing depressive symptoms. 10 In addition, studies found that the number of teeth, not just edentulousness, was associated with incident depressive symptoms.11, 12 However, Chu et al. utilized a group aged 40–79 years from the National Institute for Longevity Sciences‐Longitudinal Study of Aging (NILS‐LSA). 11 Ehrenthal et al. used the data of patients aged between 18 and 80 years from the Department of Dentistry and Periodontology at Kiel University. 12 Findings from studies that include younger or middle‐aged adults may not be extrapolated to older adults. A natural experimental design study by Matsuyama et al., analyzing the Behavioral Risk Factor Surveillance System (BRFSS) in 2006, 2008, or 2010, showed that tooth loss had a causal effect on depression in US adults; however, older adults aged ≥60 years were unaffected. 13 Thus, more research is needed to explore the relationship between the number of teeth and a broader range of mental disorders in older adults, as well as early prevention and intervention for mental health issues in older adults.
Older adults may believe tooth loss is a normal part of aging and make adjustments accordingly, potentially reducing the psychological impact. 35 This adaptation may reduce the emotional response to tooth loss in older adults. 13 However, this study revealed that if the number of teeth was decreased suddenly and meaningfully, older adults could not adapt to the change in a short period, 23 and may have developed psychological distress. Therefore, future studies should pay more attention to changes in the number of teeth in older adults. To monitor changes in the number of teeth in older adults promptly, encouraging them to undergo regular dental checkups becomes a primary task. Previous literature also found that regular dental checkups helped maintain the number of teeth in older adults.36, 37, 38
The mechanisms linking fewer teeth to psychological distress may be bidirectional or multifactorial. A meta‐analysis found that patients with common mental disorders had significantly higher rates of tooth decay and tooth loss than the general population. 39 However, this study excluded older adults with a history of mental illness at baseline. Therefore, verifying the effect of the number of teeth on psychological distress is preferable. Nutritional factors may explain the association between fewer teeth and mental disorders. Previous studies have found that oral health or maintenance of ≥20 teeth affects food choices and nutritional status in older adults.40, 41, 42 B vitamins, branched‐chain amino acid (BCAAs) intake, folate, and homocysteine levels are associated with psychological distress.17, 18, 43 Moreover, poor diet quality and excessive intake of sweets and snacks/fast food are also associated with depression.44, 45 Studies have found that providing additional nutritional counseling to older adults with dentures is more effective in improving their nutritional intake compared to only using dentures.46, 47 Therefore, in addition to maintaining the number of teeth in older adults, nutritional counseling should be performed to ensure healthy dietary intake and prevent psychological distress.
The number of teeth is associated with social participation, a known factor influencing the emotional well‐being of older adults. Previous studies indicated that the inability to smile, laugh, and show teeth freely owing to poor oral health may exacerbate social withdrawal, isolation, and low self‐esteem.10, 48 A cross‐national study stated that poor oral health was associated with greater social isolation, with the relationship between fewer remaining teeth and social isolation being stronger among edentulous individuals. 19 Previous studies found that having few teeth and/or not using dentures predicted future home boundness and a decline in higher‐level functional capacity in older adults.20, 49 These findings highlight the importance of social participation in the relationship between tooth loss and psychological distress. However, our participants were older adults who underwent health checkups and generally exhibited high levels of social participation.50, 51 Therefore, our results indicate a strong association between edentulism, changes in the number of teeth, and psychological distress in older adults.
Additionally, removable dentures or dental implants can replace lost teeth and partially restore natural tooth function. Furthermore, the results of this study showed that dentures may reduce the risk of developing psychological distress, but only in those with ≥20 teeth at baseline. In two studies on the emotional impact of missing teeth in edentulous patients, approximately 45% of participants were unable to accept the fact that they had missing teeth despite wearing dentures.23, 52 Such a result reflects the psychological impact of having ≤10 teeth or even being edentulous, which offsets the help of dentures. Therefore, it is crucial to maintain natural teeth as much as possible.
The strengths of the present study include its first attempt to verify the psychological impact of the changes in tooth number in older adults, longitudinal design, large sample size, and control for potential confounders. However, this study has some limitations. First, the study enrolled only older adults in Taipei who actively participated in health examinations, and the findings may not be directly transferrable to other countries or settings. Second, individuals with more severe psychological distress may not participate in health examinations, and the reported findings may be underestimated. Third, owing to the observational research design of this study, we cannot infer a causal relationship between tooth loss and psychological distress. Therefore, future studies should utilize more rigorous methods to establish causal relationships, such as experimental studies and randomized controlled trials.
In conclusion, this study reveals that being edentulous or experiencing a rapid decline in the number of teeth predicts the development of psychological distress in older adults. Thus, regular dental checkups, nutritional counseling, and the use of dentures are critical in mitigating the adverse psychological effects of tooth loss. Moreover, integrating mental health monitoring in dental care plans is essential for the overall well‐being of older adults. These findings emphasize the need for a holistic approach to dental care that considers physical and psychological health.
AUTHOR CONTRIBUTIONS
Yi‐Chang Chou and Feng‐Shiang Cheng contributed to the conception, design, data analysis and interpretation, and drafted and critically revised the manuscript; Shih‐Han Weng contributed to the conception, design, data interpretation, and critically revised the manuscript; Hsiao‐Yun Hu contributed to the conception, design, data acquisition, analysis and interpretation, and drafted and critically revised the manuscript. All authors provided their final approval and agreed to be accountable for all aspects of the study.
CONFLICT OF INTEREST STATEMENT
The authors have no conflicts.
SPONSOR'S ROLE
None.
FINANCIAL DISCLOSURE
This study was supported by the Ministry of Science and Technology, Taiwan (MOST 111‐2314‐B‐532‐002), and Taipei City Hospital, Taiwan (TPCH‐112‐03).
Supporting information
Supplementary Table S1. Association of number of teeth and psychological distress by multivariable adjusted GEE analysis.
ACKNOWLEDGMENTS
This study used data from the Taipei City Public Health Database provided by the Department of Health, Taipei City Government, and managed by the Center for Public Health. The interpretations and conclusions contained herein do not represent those of the Department of Health, Taipei City Government, or Center for Public Health.
Chou Y‐C, Cheng F‐S, Weng S‐H, Hu H‐Y. Association of changes in the number of teeth on psychological distress among community‐dwelling older adults in Taiwan. J Am Geriatr Soc. 2025;73(3):802‐811. doi: 10.1111/jgs.19297
Meeting presentation: None.
Yi‐Chang Chou and Feng‐Shiang Cheng contributed equally to this study and share the first authorship.
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Associated Data
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Supplementary Materials
Supplementary Table S1. Association of number of teeth and psychological distress by multivariable adjusted GEE analysis.