IJMR Interact J Med Res Interactive Journal of Medical Research 1929-073X JMIR Publications Toronto, Canada v13i1e48778 39671593 10.2196/48778 Original Paper Original Paper Decomposition Analysis of the Prevalence of Denture Use Between Rural and Urban Older Individuals With Edentulism in China: Cross-Sectional Study de Azevedo Cardoso Taiane Chen Li Yu Li Yuan Lei BM 1 https://orcid.org/0000-0001-9069-9481 Yuan Yuan BM 2 3 https://orcid.org/0009-0000-0151-7149 Ren Haotian BM 4 https://orcid.org/0000-0002-3706-9189 Zhang Feng BM 1 https://orcid.org/0009-0002-8458-7787 Zhao Zhe MM 1 https://orcid.org/0009-0001-2701-378X Jiang Qinqin MIM 1 https://orcid.org/0009-0004-1249-4121 Wei Zhenbang MM 1 https://orcid.org/0009-0000-9490-8148 Sun Jin-hai PhD 1
Department of Health Management Faculty of Military Health Service Naval Medical University No 800 Xiangyin Road Shanghai, 200433 China 86 021 81871455 sunjinhai2003@sina.cn
https://orcid.org/0000-0001-5474-8047 Department of Health Management Faculty of Military Health Service Naval Medical University Shanghai China Xiuwen County Bureau of Statistics GuiZhou China College of Humanities and Management Guizhou University of Traditional Chinese Medicine GuiZhou China Department of Stomatology Changhai Hospital Naval Medical University Shanghai China Corresponding Author: Jin-hai Sun sunjinhai2003@sina.cn 2024 13 12 2024 13 e48778 6 5 2023 8 6 2023 29 6 2023 30 9 2024 ©Lei Yuan, Yuan Yuan, Haotian Ren, Feng Zhang, Zhe Zhao, Qinqin Jiang, Zhenbang Wei, Jin-hai Sun. Originally published in the Interactive Journal of Medical Research (https://www.i-jmr.org/), 13.12.2024. 2024

This is an open-access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work, first published in the Interactive Journal of Medical Research, is properly cited. The complete bibliographic information, a link to the original publication on https://www.i-jmr.org/, as well as this copyright and license information must be included.

 Background

Edentulism impacts the physical health and quality of life of older individuals. The prevalence, influencing factors, and differences in terms of edentulism in urban and rural areas of China are unclear.

 Objective

This study investigated the denture-wearing conditions and causes affecting older patients with edentulism in urban and rural areas of China and analyzed the differences.

 Methods

This cross-sectional study included the data of 5139 older individuals (age>65 years) with edentulism obtained from 23 Chinese provinces in 2018. Participants were divided into urban and rural groups based on their household registration. Factors influencing denture use in both groups were explored using binary logistic regression, while factors influencing differences in denture wearing in both groups were explored using the Fairlie decomposition model.

 Results

Of the 5139 participants, 67.05% (808/1205) from urban areas and 51.12% (2011/3934) from rural areas wore dentures. In the urban group, participants with a higher level of education (1-6 years: odds ratio [OR] 2.093, 95% CI 1.488-2.945; ≥7 years: OR 2.187, 95% CI 1.565-3.055) or who exercised (OR 2.840, 95% CI 2.016-3.999) preferred wearing dentures, but individuals with BMI<18.5 kg/m2 (OR 0.558, 95% CI 0.408-0.762) or widowed (OR 0.618, 95% CI 0.414-0.921) did not. In the rural group, a higher level of education (1-6 years: OR 1.742, 95% CI 1.429-2.123; ≥7 years: OR 1.498, 95% CI 1.246-1.802), living alone (OR 1.372, 95% CI 1.313-1.663), exercise (OR 1.612, 95% CI 1.340-1.940), high economic status (OR 1.234, 95% CI 1.035-1.472), residence in the eastern area (OR 2.045, 95% CI 1.723-2.427), presence of chronic diseases (1 disease: OR 1.534, 95% CI 1.313-1.793; ≥2 diseases: OR 1.500, 95% CI 1.195-1.882) were positively associated and age≥80 years (OR 0.318, 95% CI 0.247-0.408), BMI<18.5 kg/m2 (OR 0.692, 95% CI 0.590-0.813), and widowed (OR 0.566, 95% CI 0.464-0.690) or other marital status (OR 0.600, 95% CI 0.392-0.918) were negatively associated with denture use. The Fairlie decomposition model revealed that the number of chronic diseases (16.34%), education level (11.94%), region of residence (11.00%), annual income (10.55%), exercise (6.81%), and age (–0.92%) were the main factors responsible for differences between urban and rural edentulism and could explain the difference in the denture-wearing rate (58.48%) between both groups.

 Conclusions

Older individuals with edentulism with a higher education level and who exercise are more willing to wear dentures, while those with BMI<18.5 kg/m2 show a decreased willingness to wear dentures in both urban and rural areas in China. Controlling the number of chronic diseases, improving the education level and annual income, cultivating good exercise habits, and bridging the gap between the economic status of the east and west can narrow the differences in denture wearing among urban and rural older individuals with edentulism.

 oral health older adults with edentulism edentulism denture decomposition analysis China Introduction

Oral diseases have become a public health concern worldwide [1], affecting 64.6% of the Chinese older adult population in varying degrees [2,3]. Oral diseases particularly affect older individuals and are majorly responsible for the disease burden [4,5]. Edentulism is the loss of all natural teeth, and it is 1 of the most serious oral diseases [6]. Patients with edentulism face serious oral health risks, adversely affecting their health and quality of life [7]. The absolute disease burden due to edentulism is increasing in many countries [8].

According to current research, patients with edentulism are more prone to chronic diseases (eg, hypertension [9], diabetes, chronic kidney disease, cardiovascular disease, and asthma) [10], psychological abnormalities (eg, sleep disorders) [11], and increased cognitive impairment [12]. Reportedly, edentulism increases the risk of all-cause mortality [13] and a poorer quality of life [14].

Several surveys have reported that the prevalence of edentulism among middle-aged and older Chinese individuals ranges from approximately 8% to 28% [15-19]. China is experiencing a crisis of rapid population aging. According to the Seventh National Population Census Data released by the State Council of China, in 2021, the older adult population (age>65 years) accounted for 190 million (approximately 13.5% of the total population), which is >14% in some provinces [20]. By 2050, the older adult population in China will be nearly 487 million, accounting for 34.9% of the total population. This gradual aging phenomenon indicates that the older adult population in China will suffer from serious oral health problems, such as edentulism.

Replacing missing teeth is the most effective treatment for edentulism, while dentures are the main treatment modality [21]. Particularly, older individuals with edentulism are more likely to wear dentures. Wearing dentures can effectively help restore masticatory function [22], prevent malnutrition [23], improve oral health [12], lower the incidence of cognitive impairment and mental illness [24], lower all-cause mortality [13], and improve the overall physical health of the older [12,22,25].

To the best of our knowledge, there exists a limited body of research that has reported on the use of dentures among older individuals with edentulism in China. This prevailing circumstance is regrettably unfavorable and undermines the comprehensive exploration of oral health services and the formulation of pertinent policies in the Chinese context. China, as a geographically expansive and densely populated nation, has been the subject of numerous investigations revealing an escalating pattern of health disparities between urban and rural residents in response to the nation’s burgeoning economic growth [26]. This discernible phenomenon has been substantiated in domains encompassing psychological well-being, the incidence of chronic ailments, and atmospheric pollution levels [27-29]. Curiously, the realm of oral hygiene, acknowledged as a pivotal determinant influencing the health of the older populace [30,31], has regrettably remained marginalized in the academic endeavors of Chinese scholars. Notably absent is a substantive examination of the urban-rural dichotomy in denture adoption rates among geriatric cohorts with edentulism, an omission that represents a conspicuous deficiency within China’s public health research landscape. The prevailing lacuna necessitates the exploration of causative factors underpinning the incongruities in denture usage rates among older individuals with edentulism in China. This imperative investigation can furnish the Chinese governmental apparatus with actionable policy recommendations tailored to the augmentation of oral public health endeavors. These recommendations are envisaged to play a catalytic role in ameliorating the existing health disparities between China’s urban and rural spheres, thereby aligning harmoniously with the overarching objective of mitigating health inequalities on a broader societal canvas.

To address these scholarly exigencies, this study embarked on an in-depth inquiry into the unmet requirements for denture use within the edentulous older demographic in China, as well as its main influencing factors. Furthermore, it is pertinent to acknowledge the salient socioeconomic and health differentials existing between the urban and rural populace of China [26,32-34], an observation that affects the realm of oral health. There is evidence of the complex interactions of socioeconomic inequalities, urban-rural economic differentials, and the socioenvironmental milieu across different life stages shaping inconsistent oral health outcomes [35-37].

Considering these findings, this study conducted a comparative analysis of denture use among urban and rural older individuals with edentulism in China. We analyzed the differences in denture use among urban and rural older individuals with edentulism and further identified the factors influencing those differences in order to inhibit the prevailing inconsistencies in oral health outcomes between urban and rural areas. Our aim was to provide key insights into the calibration of oral health service policies and the enhancement of the oral and holistic well-being of the older adult population in China.

 Methods Data Sources

This was a cross-sectional study to analyze the prevalence of denture use between rural and urban older individuals with edentulism. Data were obtained from a survey conducted by the Chinese Longitudinal Healthy Longevity Survey project team in 2018, covering 23 Chinese provinces. Multistage cluster sampling was used, and about 50% of counties, county-level cities, and municipal districts in all survey provinces were randomly selected as survey areas. These areas were divided into large and small “sample counties” for the survey. Data were collected by centralized trained investigators who were assessed to be qualified for duty.

 Ethical Considerations

The study was approved by the Research Ethics Committee of Peking University and Duke University. Written informed consent was obtained from all participants during the face-to-face interview. Data collection was approved by the Research Ethics Committee of Peking University. The data were made public after anonymous processing, and detailed design reports are available on the university’s website [38-40]. As the data analyzed are available in the public domain, separate ethical approval was not required for this study.

A total of 15,874 participants were surveyed, approved by the Research Ethics Committee of Peking University (IRB00001052-13074).

 Sample Selection

Participants needed to meet the following inclusion criteria: (1) be ≥65 years old, (2) have edentulism, and (3) answer the questionnaire completely. A total of 10,641 (67.03%) participants without edentulism were excluded from our study; 22 (0.14%) participants were excluded because they did not respond to the indicator of whether dentures should be worn; 3 (0.02%) participants aged <65 years and 69 (0.43%) participants who did not respond to basic information were also excluded. Finally, 5139 (32.37%) participants were included in this study.

Edentulism and Denture Use Assessments

Participants with edentulism were assessed by asking the question “How many teeth do you have (excluding dentures)?” Participants who answered 0 were considered edentulous, while those who answered anything other than 0 were excluded from this study.

Participants were asked the question “Do you wear dentures?”, with “yes” or “no” as a response.

 Variables

Participants were divided into urban and rural groups based on China’s household registration classification (hukou).

With similar other studies as references, the covariates included in this study comprised 4 indicator types: demographic characteristics, lifestyle characteristics, economic status, and health status. The demographic characteristics included age, sex, education level, and marital status; the lifestyle characteristics included the residential status, any history of smoking, alcohol consumption, and exercise; the economic status included the annual income and residential region; and the health status included the BMI and chronic disease status. The variable and reference group settings for all indicators are described in detail in Table S1 in Multimedia Appendix 1.

 Statistical Analysis

The basic information was analyzed using descriptive statistical methods. Wearing dentures was used as the outcome variable, 1-way ANOVA was performed using the chi-square test, and binary logistic regression was conducted to explore the factors influencing denture use in the urban and rural groups. All factors were entered into the logistic regression analysis, and forward stepwise regression was performed.

The Fairlie decomposition model was used to perform decomposition analysis. It decomposed the difference between the urban and rural groups with edentulism and without dentures into 2 based on the difference in the observation of characteristic factors and coefficients [26,41]. Specific application examples from several studies exist [42-45]. The decomposition equation used in this study was as follows:

where are the average probabilities of binary outcomes for denture wearing in the urban and rural groups, respectively; F is the cumulative distribution function of the logical distribution; represents the total difference due to group differences; and are the sample sizes of the 2 groups of the comparator.

The first term in parentheses in the equation represents the part of the gap due to the difference in the group of observed characteristics and the part attributable to the difference in the estimated coefficient, while the second term represents the part due to the difference in the Y level [43].

 Results Participant Characteristics

The participant selection process is presented in Figure 1. Table 1 presents the results of the chi-square test for the basic participant characteristics of denture wearers and nonwearers among older individuals with edentulism in the urban and rural groups. Participants from the urban area constituted 23.45% (1205/5139) of the study population. The results revealed that except for the marital status, there were significant differences in the distribution characteristics of other factors between urban and rural participants (P<.05).

Participant selection flowchart.

Basic participant characteristics of denture wearers and nonwearers among older individuals with edentulism in urban and rural areas in China.

Characteristics Urban group (n=1205), n (%) Rural group (n=3934), n (%)
Dentures wearers (χ21=94.591; P<.001)
No 397 (32.95) 1923 (48.88)
Yes 808 (67.05) 2011 (51.12)
Age (years; χ21=8.353; P=.004)
<80 140 (11.62) 589 (14.97)
≥80 1065 (88.38) 3345 (85.03)
Sex (χ21=16.457; P<.001)
Female 498 (41.33) 1373 (34.90)
Male 707 (58.67) 2561 (65.10)
BMI (kg/m2; χ23=31.714; P<.001)
18.5-23.9 539 (44.73) 1874 (47.64)
<18.5 313 (25.98) 1206 (30.66)
24.0-27.9 240 (19.92) 562 (14.29)
≥28.0 113 (9.38) 292 (7.42)
Education level (years; χ22=141.516; P<.001)
0 492 (40.83) 2347 (59.66)
1-6 325 (26.97) 823 (20.92)
≥7 388 (32.20) 764 (19.42)
Marital status (χ22=0.292; P=.846)
Married and living with spouse 279 (23.15) 939 (23.87)
Widowed 888 (73.69) 2876 (73.11)
Other 38 (3.15) 119 (3.02)
Living status (χ22=203.117; P<.001)
Living with household members 938 (77.84) 3176 (80.73)
Living alone 136 (11.29) 681 (17.31)
Living in an institution 131 (10.87) 77 (1.96)
Smoking (χ21=21.289; P<.001)
No 1101 (91.37) 3397 (86.35)
Yes 104 (8.63) 537 (13.65)
Alcohol consumption (χ21=7.936; P=.005)
No 1098 (91.12) 3470 (88.21)
Yes 107 (8.88) 464 (11.79)
Exercise (χ21=49.507; P<.001)
No 861 (71.45) 3184 (80.94)
Yes 344 (28.55) 750 (19.06)
Annual income (χ23=508.961; P<.001)
Very low 119 (9.88) 1272 (32.33)
Low 109 (9.05) 843 (21.43)
Middle 162 (13.44) 504 (12.81)
High 815 (67.63) 1315 (33.43)
Residential region (χ22=92.747; P<.001)
Central 188 (15.60) 994 (25.27)
Western 251 (20.83) 1049 (26.66)
Eastern 766 (63.57) 1891 (48.07)
Number of chronic diseases (χ22=300.031; P<.001)
0 470 (39.00) 2286 (58.11)
1 344 (28.55) 1184 (30.10)
≥2 391 (32.45) 464 (11.79)
Assessment of the Proportion of Denture Wearing Across Provinces

Table S2 in Multimedia Appendix 2 shows the results of the chi-square test for the proportion of denture wearing among older individuals with edentulism by region (central, western, and eastern) and by hukou (urban and rural). The results revealed that 67.05% (808/1205) of participants in the urban group used dentures (95% CI 64.40-69.71), while 51.12% (2011/3934) of participants in the rural group used dentures (95% CI 49.56-52.67), and the difference was statistically significant (χ21=94.591, P<.001). The prevalence of denture use across the various regions of China was as follows: central region, 45.26% (535/1182; 95% CI 42.42-48.10); western region, 47.92% (623/1300; 95% CI 45.20-50.64); and eastern region, 62.51% (1661/2657; 95% CI 60.67-64.36). The regional differences were statistically significant (χ22=132.086, P<.001).

Based on the survey results, we mapped the proportion of denture use among older individuals with edentulism across 23 Chinese provinces (Figure 2 and Table S3 in Multimedia Appendix 3). We observed that the highest proportion was in Liaoning (81.36%, 95% CI 74.23-88.49), while the lowest proportion was in Hunan (21.91%, 95% CI 15.57-28.05) among the provinces surveyed.

Proportion of denture use among older individuals with edentulism across 23 Chinese provinces.

 Distribution of Denture Wearers and Nonwearers Among Older Individuals With Edentulism

Table 2 reveals the results of the chi-square test for the distribution characteristics of denture wearers and nonwearers among older participants with edentulism in the urban and rural groups. The results revealed that the distribution of certain factors among participants with dentures in urban and rural groups was significantly different; certain differences were also observed in those without dentures. Age, marital status, alcohol consumption, and exercise were significantly different among participants in urban and rural groups who were denture wearers; however, no differences were observed in denture nonwearers.

Distribution of characteristics of denture wearers and nonwearers among older individuals with edentulism in urban and rural areas in China.

Characteristics Denture wearers Denture nonwearers
Urban group (n=808), n (%) Rural group (n=2011), n (%) Urban group (n=397), n (%) Rural group (n=1923), n (%)
Age (years; wearers: χ21=30.186, P<.001; nonwearers: χ21=0.009, P>=.924)
<80 119 (14.73) 485 (24.12) 21 (5.29) 104 (5.41)
≥80 689 (85.27) 1526 (75.88) 376 (94.71) 1819 (94.59)
Sex (wearers: χ21=2.840, P=.092; nonwearers: χ21=7.534, P=.006)
Female 355 (43.94) 814 (40.48) 143 (36.02) 559 (29.07)
Male 453 (56.06) 1197 (59.52) 254 (63.98) 1364 (70.93)
BMI (kg/m2; wearers: χ23=6.276, P=.099; nonwearers: χ23=17.981, P<.001)
<18.5 162 (20.05) 449 (22.33) 151 (38.04) 757 (39.37)
18.5-23.9 388 (48.02) 1012 (50.32) 151 (38.04) 862 (44.83)
24.0-27.9 178 (22.03) 384 (19.09) 62 (15.62) 178 (9.26)
≥28.0 80 (9.90) 166 (8.25) 33 (8.31) 126 (6.55)
Education level (years; wearers: χ22=82.549, P<.001; nonwearers: χ22=25.672, P<.001)
0 268 (33.17) 1010 (50.22) 224 (56.42) 1337 (69.53)
1-6 244 (30.20) 550 (27.35) 81 (20.40) 273 (14.20)
≥7 296 (36.63) 451 (22.43) 92 (23.17) 313 (16.28)
Marital status (wearers: χ22=7.918, P=.019; nonwearers: χ22=0.334, P=.846)
Married and living with spouse 227 (28.09) 674 (33.52) 52 (13.10) 265 (13.78)
Widowed 557 (68.94) 1277 (63.50) 331 (83.38) 1599 (83.15)
Other 24 (2.97) 60 (2.98) 14 (3.53) 59 (3.07)
Living status (wearers: χ22=106.039, P<.001; nonwearers: χ22=107.303, P<.001)
Living with household members 633 (78.34) 1600 (79.56) 305 (76.83) 1576 (81.96)
Living alone 96 (11.88) 375 (18.65) 40 (10.08) 306 (15.91)
Living in an institution 79 (9.78) 36 (1.79) 52 (13.10) 41 (2.13)
Smoking (wearers: χ21=21.830, P<.001; nonwearers: χ21=5.471, P=.019)
No 732 (90.59) 1685 (83.79) 369 (92.95) 1712 (89.03)
Yes 76 (9.41) 326 (16.21) 28 (7.05) 211 (10.97)
Alcohol consumption (wearers: χ21=8.700, P=.003; nonwearers: χ21=2.371, P=.124)
No 730 (90.35) 1735 (86.28) 368 (92.70) 1735 (90.22)
Yes 78 (9.65) 276 (13.72) 29 (7.30) 188 (9.78)
Exercise (wearers: χ21=35.094, P<.001; nonwearers: χ21=0.087, P=.768)
No 518 (64.11) 1512 (75.19) 343 (86.40) 1672 (86.95)
Yes 290 (35.89) 499 (24.81) 54 (13.60) 251 (13.05)
Annual income (wearers: χ23=328.842, P<.001; nonwearers: χ23=160.774, P<.001)
Very low 67 (8.29) 649 (32.27) 52 (13.10) 623 (32.40)
Low 74 (9.16) 403 (20.04) 35 (8.82) 440 (22.88)
Middle 103 (12.75) 260 (12.93) 59 (14.86) 244 (12.69)
High 564 (69.80) 699 (34.76) 251 (63.22) 616 (32.03)
Residential region (wearers: χ22=18.504, P<.001; nonwearers: χ22=67.608, P<.001)
Central 118 (14.60) 417 (20.74) 70 (17.63) 577 (30.01)
Western 168 (20.79) 455 (22.63) 83 (20.91) 594 (30.89)
Eastern 522 (64.60) 1139 (56.64) 244 (61.46) 752 (39.11)
Number of chronic diseases (wearers: χ22=144.694, P<.001; nonwearers: χ22=128.438, P<.001)
0 298 (36.88) 1012 (50.32) 172 (43.32) 1274 (66.25)
1 231 (28.59) 708 (35.21) 113 (28.46) 476 (24.75)
≥2 279 (34.53) 291 (14.47) 112 (28.21) 173 (9.00)
Logistic Regression Results

The results of binary logistic regression for the multivariate analysis of older individuals with edentulism in the urban and rural groups who were denture wearers are presented in Table 3. The results revealed that in the urban group, a higher level of education (1-6 years: odds ratio [OR] 2.093, 95% CI 1.488-2.945; ≥7 years: OR 2.187, 95% CI 1.565-3.055) and who exercised (OR 2.840, 95% CI 2.016-3.999) were protective factors for denture use in older individuals with edentulism, while BMI<18.5 kg/m2 (OR 0.558, 95% CI 0.408-0.762) and a widowed marital status (OR 0.618, 95% CI 0.414-0.921) were risk factors for denture use in older individuals with edentulism. In the rural group, a higher level of education (1-6 years: OR 1.742, 95% CI 1.429-2.123; ≥7 years: OR 1.498, 95% CI 1.246-1.802), living alone (OR 1.372, 95% CI 1.313-1.663), exercise (OR 1.612, 95% CI 1.340-1.940), a high economic status (OR 1.234, 95% CI 1.035-1.472), residence in the eastern area (OR 2.045, 95% CI 1.723-2.427), the presence of chronic diseases (1 disease: OR 1.534, 95% CI 1.313-1.793; ≥2 diseases: OR 1.500, 95% CI 1.195-1.882) were protective factors for denture use in older individuals with edentulism, while age ≥80 years (OR 0.318, 95% CI 0.247-0.408), BMI <18.5 kg/m2 (OR 0.692, 95% CI 0.590-0.813), and widowed (OR 0.566, 95% CI 0.464-0.690) or other marital status (OR 0.600, 95% CI 0.392-0.918) were risk factors for dentures in older individuals with edentulism.

Logistic regression results of denture use in older individuals with edentulism in urban and rural areas in China.

Variables Urban group Rural group
P value ORa (95% CI) P value OR (95% CI)
Age (years)
<80 —b 1.000 — 1.000
≥80 .439 0.804 (0.462-1.398) <.001 0.318 (0.247-0.408)
Sex
Female — — — —
Male .072 1.327 (0.975-1.806) .978 0.998 (0.839-1.186)
BMI (kg/m2)
18.5-23.9 — 1.000 — 1.000
<18.5 <.001 0.558 (0.408-0.762) <.001 0.692 (0.590-0.813)
24.0-27.9 .954 0.989 (0.685-1.429) .003 1.384 (1.113-1.721)
≥28.0 .781 0.935 (0.582-1.502) .847 1.027 (0.782-1.350)
Education level (years)
0 — 1.000 — 1.000
1-6 <.001 2.093 (1.488-2.945) <.001 1.742 (1.429-2.123)
≥7 <.001 2.187 (1.565-3.055) <.001 1.498 (1.246-1.802)
Marital status
Married and living with spouse — 1.000 — 1.000
Widowed .018 0.618 (0.414-0.921) <.001 0.566 (0.464-0.690)
Other .158 0.562 (0.253-1.251) .019 0.600 (0.392-0.918)
Living status
Living with household members — 1.000 — 1.000
Living alone .565 1.138 (0.733-1.765) .001 1.372 (1.131-1.663)
Living in an institution .375 0.826 (0.542-1.259) .849 1.048 (0.645-1.705)
Smoking
No — 1.000 — 1.000
Yes .389 1.251 (0.751-2.083) .574 1.066 (0.853-1.331)
Alcohol consumption
No — — — —
Yes .966 1.011 (0.618-1.653) .282 1.134 (0.902-1.425)
Exercise
No — 1.000 — 1.000
Yes <.001 2.840 (2.016-3.999) <.001 1.612 (1.340-1.940)
Annual income
Very low — 1.000 — 1.000
Low .123 1.590 (0.882-2.868) .608 1.053 (0.864-1.284)
Middle .387 1.262 (0.745-2.140) .051 1.263 (0.999-1.598)
High .055 1.520 (0.991-2.332) .019 1.234 (1.035-1.472)
Residential region
Central — 1.000 — 1.000
Western .795 1.059 (0.689-1.626) .648 1.046 (0.862-1.269)
Eastern .230 1.252 (0.868-1.808) <.001 2.045 (1.723-2.427)
Number of chronic diseases
0 — 1.000 — 1.000
1 .918 1.017 (0.740-1.398) <.001 1.534 (1.313-1.793)
≥2 .164 1.253 (0.912-1.722) <.001 1.500 (1.195-1.882)

aOR: odds ratio.

bNot applicable.

 Decomposition Analysis Results

Tables 4 and 5 reveal the differential decomposition of denture-wearing prevalence among older individuals with edentulism in the urban and rural groups. The results revealed that the explanatory degree of the model was 58.48%, indicating that this study could explain 58.48% of the difference in the denture-wearing rate between urban and rural older individuals with edentulism, and the remaining 41.52% accounted for urban and rural characteristics and unincluded observation indicators. The explainable part reveals that the main factors contributing to this difference were the number of chronic diseases (16.34%), education level (11.94%), residence region (11.00%), annual income (10.55%), exercise (6.81%), and age (–0.92%).

Terms of decomposition in the Fairlie decomposition model.

Terms of decomposition Denture use
Difference 0.15935487
Explained (%) 0.09317312 (58.48%)
Nonexplained (%) 0.06616842 (41.52%)

Results of the explainable part of the Fairlie decomposition model (contribution % shown).

Covariates P value β Contribution (95% CI)
Demographic information
Age <.001 –0.0014637 –0.92 (–0.0022267 to –0.0007007)
Sex .299 0.0009324 0.59 (–0.0008272 to 0.0026921)
Education level <.001 0.0190212 11.94 (0.0140899 to 0.0239526)
Married status .168 0.0003782 0.24 (–0.0001591 to 0.0009156)
Lifestyle status
Living status .018 0.0028159 1.77 (0.0004876 to 0.0051442)
Smoking .468 –0.0005955 –0.37 (–0.0022039 to 0.0010129)
Alcohol consumption .412 –0.0004585 –0.29 (–0.0015550 to 0.0006380)
Exercise <.001 0.0108532 6.81 (0.0084449 to 0.0132615)
Economic status
Annual income <.001 0.0168183 10.55 (0.0081524 to 0.0254843)
Residence region <.001 0.0175302 11.00 (0.0138448 to 0.0212155)
Health status
BMI .408 0.0006835 0.43 (–0.0009352 to 0.0023021)
Number of chronic diseases <.001 0.0260315 16.34 (0.0194942 to 0.0325688)
Discussion Principal Findings

Our study revealed that 54.86% of Chinese older individuals with edentulism wear dentures, among which the denture-wearing rate of individuals with edentulism in urban areas is higher than that in rural areas, indicating that older individuals with edentulism in urban areas focus on their oral problems. In terms of regional distribution, the denture-wearing rate in the eastern region was the highest, followed by the western and central regions. Studies have reported that this is probably due to the higher health literacy level among older individuals in the eastern region and their active awareness and behavior in promoting oral health. Additionally, the higher economic level of residents in the eastern region provide a certain economic basis for the residents to obtain good oral health care. Thus, more adequate educational and medical resources help provide better access to denture-related treatment services for older individuals [46-49].

Our study revealed that age, sex, the BMI, and the education level are significant factors affecting the urban-rural distribution of older patients with edentulism (P<.05). Sex, the BMI, and the education level mainly affect the urban-rural distribution of older patients with edentulism, although the urban-rural distribution factors influencing denture-wearing older patients with edentulism are mainly age, the education level, and the marital status. Further analysis revealed that the education level is a protective factor for denture wearing among older patients with edentulism in urban and rural areas and that a higher education level could improve health literacy, the awareness of health maintenance, and the promotion of healthy behavior, leading to better use of medical resources, such as oral health clinics and oral health care aids, to promote their oral health [48,50]. Previous studies [51-53] have reported that the number of teeth can affect an individual’s choice of food and nutrient intake, and individuals without teeth are more likely to have a lean physique. In this study, a BMI of <18.5 kg/m2 was a relevant factor for denture wearing in older individuals with edentulism (urban areas: OR 0.558, 95% CI 0.408-0.762, P<.001; rural areas: OR 0.692, 95% CI 0.590-0.813, P<.001), which might be because denture use can improve the oral health of patients with edentulism, prompting them to choose more food varieties and have a more comprehensive nutritional intake, while denture nonwearers will be malnourished due to poor oral health, limited food options, and aggravated leanness.

Lifestyle habits, such as smoking and alcohol consumption, influence the use of dentures among patients with edentulism [54-56] and significantly impact the urban-rural distribution of older patients with edentulism and older patients wearing dentures (P<.05); the effects of the living status and exercise on the urban-rural distribution of older patients with edentulism and older patients wearing dentures are also significant (P<.05). However, the effects of alcohol consumption and exercise on the urban-rural distribution differences among older individuals with edentulism who do not wear dentures are not significant. Although previous studies have reported that smoking and alcohol consumption affect an individual’s oral health literacy and healthy behavior, this study did not demonstrate significant healthy behaviors among urban and rural patients with edentulism who wore dentures. Furthermore, exercise was a protective factor for denture use in older patients with edentulism (urban areas: OR 2.840, 95% CI 2.016-3.999, P<.001; rural areas: OR 1.61295% CI 1.340-1.940, P<.001). Older individuals who exercise regularly are more aware of health maintenance, have higher health requirements, and are more willing to wear dentures to maintain their quality of life and health status.

According to the provisions of the Basic Medical Insurance System for Chinese Residents, the cost of a denture for patients with edentulism is not fully reimbursed, with most of the expense being borne by the patient. Similar to previous studies [57-59], we found that the socioeconomic status and household economic status have a significant impact on dental service use. Our results revealed that the economic status and area of residence are strongly associated with the inequality of the urban-rural distribution of older patients with edentulism in China and that their impact on the difference in the urban-rural distribution of older patients with edentulism in China is significant regardless of whether the patients are denture wearers. For older patients with edentulism from rural areas, a high annual family income and residence in the eastern region were protective factors for wearing a denture. Older individuals living in urban areas have a higher and more stable financial income after retirement compared to older individuals from rural areas. Additionally, urban residents have a higher percentage of commercial health insurance than rural residents, thereby providing favorable financial support to urban patients with edentulism to obtain dentures [60,61]. In recent years, the centralized procurement policy of medical consumables has been implemented in China, and regarding oral equipment, this can significantly lower the medical burden of providing dentures to patients with edentulism and increase the proportion of dentures provided to older patients with edentulism from rural areas, thus reducing the urban-rural inequality in denture use.

Islas-Granillo et al [62] reported that chronic diseases severely impact the oral health of older adults and that older adults with multiple moderate chronic diseases are more likely to experience edentulism [54,62,63]. This study reported that regardless of whether dentures are worn, the number of chronic diseases significantly impacts the urban-rural distribution differences in older patients with edentulism. The number of chronic diseases had no significant impact on denture wearing in older patients with edentulism from urban areas but was a protective factor for older patients with edentulism from rural areas who wore dentures. The reason probably is that older patients with edentulism with chronic diseases frequently visit medical institutions, their health literacy and willingness for health maintenance are stronger, and they are in a position to maintain their oral health more actively. Wu et al [63] reported that because of behaviors, such as frequent physical examinations or hospital visits, older adults with chronic diseases have better access to health resources, including dental examinations and treatment, than those without chronic diseases.

We performed a decomposition analysis using the Fairlie model to investigate factors influencing the urban-rural differences in denture wearing among older patients with edentulism in China, which revealed that age, education level, exercise, annual household income, area of residence, and number of chronic diseases are associated with urban-rural differences in denture wearing.

 Recommendations

Based on the differences in the denture-wearing rate between older patients with edentulism from urban and rural areas, this study proposed targeted policy recommendations to improve the denture-wearing rate and to promote equity in urban and rural oral health. First, we need to focus on patients with aphthous ulcers who have poor oral health literacy and a low education level. It is recommended that Chinese family physicians give full play to health education and guidance to create oral health awareness and motivate such patients to develop good oral health habits. Second, due to the differences in family income and regional economic development, it is necessary to focus on older patients with edentulism from rural or underdeveloped areas. The government should increase the investment in health care to lower the cost of dentures for patients with edentulism, thereby facilitating patients to easily avail of denture treatment. Finally, we recommend actively improving oral health education, maintaining oral hygiene, and encouraging residents to develop an exercise routine to maintain oral health. In summary, the oral health situation of older individuals with edentulism in China is serious, and the denture-wearing rate needs to be improved. The government should adopt measures to promote oral health, increase oral health medical funding, expand basic social medical coverage, and implement a centralized procurement policy for oral medical materials to reduce the medical burden of older patients with edentulism who require dentures, thereby improving their denture-wearing rate and promoting their oral health.

 Limitations

This study has several limitations. First, older patients with edentulism are widely distributed across China; however, this study only investigated a small number of individuals in certain provinces of the country and did not cover the entire older adult population. Second, denture use among older patients with edentulism is influenced by several factors, only some of which were analyzed in this study. Third, even though the self-reported number of teeth and denture use in this study were credible, in the follow-up studies, clinical diagnosis could be made with professional instruments. Fourth, as a cross-sectional study, the causal relationship could not be elucidated, and it is suggested that a follow-up study be conducted prospectively.

 Conclusion

Herein, we analyzed the rate of denture wear and explored the existence and causes of the differences in the denture-wearing rate among older individuals with edentulism in urban and rural China. Studies have demonstrated that the proportion of denture wearers among older patients with edentulism in rural areas is significantly lower than that in urban areas. The government needs to formulate corresponding measures in terms of the number of chronic diseases, annual household income, region of residence, education level, and exercise to bridge the gap in the denture-wearing rates among older patients with edentulism in rural and urban China. The findings of this study can provide a theoretical basis for developing relevant health policies to minimize the difference in denture-wearing rates between older patients with edentulism in urban and rural areas.

Definition and measurement of variables.

Prevalence of denture wearing among older individuals with edentulism by region (central, western, and eastern) and by hukou (urban and rural).

Proportion of denture use among older individuals with edentulism across 23 Chinese provinces.

 Abbreviations OR

Odds ratio

We thank the Center for Healthy Ageing and Development Studies at Peking University for organizing the Chinese Longitudinal Healthy Longevity Survey (CLHLS) and all the participants, investigators, and assistants of the CLHLS. This study was supported by the National Social Science Foundation of China (grant number 2022-SKJJ-C-033).

 Data Availability

The data sets analyzed in this study can be found on the Peking University Open Research Data website [40].

LY and JS designed the study. YY and ZW controlled the quality of the data and performed statistical analysis. LY, ZW, HR, QJ, and FZ managed and checked all the data. JS, ZZ, ZW, and LY contributed to manuscript preparation, editing, and review. All authors have read, checked, and approved the final manuscript.

None declared.

 Benzian H Watt R Makino Y Stauf N Varenne B WHO calls to end the global crisis of oral health Lancet 2022 12 03 400 10367 1909 1910 10.1016/S0140-6736(22)02322-4 36410360 S0140-6736(22)02322-4 Jiao J Jing W Si Y Feng X Tai B Hu D Lin H Wang B Wang C Zheng S Liu X Rong W Wang W Li W Meng H Wang X The prevalence and severity of periodontal disease in Mainland China: data from the Fourth National Oral Health Survey (2015-2016) J Clin Periodontol 2021 02 48 2 168 179 10.1111/jcpe.13396 33103285 Zhang Q Li Z Wang C Liu Y Yang Y Bussell S Zhou M Wang L A comparison of DALYs for periodontal disease in China between 1990 and 2013: insights from the 2013 Global Burden of Disease study BMC Oral Health 2017 04 11 17 1 74 10.1186/s12903-017-0356-7 28399833 10.1186/s12903-017-0356-7 PMC5387189 Yu LX Wang X Feng XP Tai BJ Hu DY Wang B Wang CX Zheng SG Liu XN Rong WS Wang WJ Si Y Lin HC The relationship between different types of caries and periodontal disease severity in middle-aged and elderly people: findings from the 4th National Oral Health Survey of China BMC Oral Health 2021 05 03 21 1 229 10.1186/s12903-021-01585-1 33941169 10.1186/s12903-021-01585-1 PMC8094505 Cheng ML Xu MR Xie YY Gao XL Wu HJ Wang X Feng XP Tai BJ Hu DY Lin HC Wang B Zheng SG Liu XN Rong WS Wang WJ Wang CX Si Y Utilisation of oral health services and economic burden of oral diseases in China Chin J Dent Res 2018 21 4 275 284 10.3290/j.cjdr.a41086 30264044 851860 Go H Kim E Jung H Ahn SV Shin H Amano A Choi Y Incidence of edentulism among older adults using the Korean National Health Insurance Service database, 2013-2018 Epidemiol Health 2022 44 e2022091 10.4178/epih.e2022091 36265516 epih.e2022091 PMC10089706 Atanda AJ Livinski AA London SD Boroumand S Weatherspoon D Iafolla TJ Dye BA Tooth retention, health, and quality of life in older adults: a scoping review BMC Oral Health 2022 05 18 22 1 185 10.1186/s12903-022-02210-5 35585618 10.1186/s12903-022-02210-5 PMC9118621 Li X Man J Chen H Yang X Spatiotemporal trends of disease burden of edentulism from 1990 to 2019: a global, regional, and national analysis Front Public Health 2022 10 940355 10.3389/fpubh.2022.940355 36518579 PMC9742533 Xu K Yu W Li Y Li Y Wan Q Chen L Dong Y Tay FR Niu L Association between tooth loss and hypertension: a systematic review and meta-analysis J Dent 2022 08 123 104178 10.1016/j.jdent.2022.104178 35661800 S0300-5712(22)00234-2 Zhang Y Leveille SG Shi L Multiple chronic diseases associated with tooth loss among the US adult population Front Big Data 2022 5 932618 10.3389/fdata.2022.932618 35844965 PMC9283677 Vago EL Frange C DA Paz Oliveira G Juliano ML Machado MA Coelho FMS The association between sleep disturbances and tooth loss among post-stroke patients Arq Neuropsiquiatr 2022 02 80 2 173 179 10.1590/0004-282X-ANP-2020-0368 35352755 S0004-282X2022000200173 PMC9648926 Tan LF Chan YH Merchant RA Association between dentition and frailty and cognitive function in community-dwelling older adults BMC Geriatr 2022 07 25 22 1 614 10.1186/s12877-022-03305-y 35879659 10.1186/s12877-022-03305-y PMC9310464 Bond JC McDonough R Alshihayb TS Kaye EA Garcia RI Heaton B Edentulism is associated with increased risk of all-cause mortality in adult men J Am Dent Assoc 2022 07 153 7 625 634.e3 10.1016/j.adaj.2021.11.009 35241269 S0002-8177(21)00715-7 Rodakowska E Jamiolkowski J Baginska J Kaminska I Gabiec K Stachurska Z Kondraciuk M Dubatowka M Kaminski KA Oral health-related quality of life and missing teeth in an adult population: a cross-sectional study from Poland Int J Environ Res Public Health 2022 01 31 19 3 1626 10.3390/ijerph19031626 35162649 ijerph19031626 PMC8834766 Ren C McGrath C Yang Y Edentulism and associated factors among community-dwelling middle-aged and elderly adults in China Gerodontology 2017 06 34 2 195 207 10.1111/ger.12249 27709661 Qu X Zhang J Wang Q Duan D Zhu T Zhang W Edentulism and select chronic diseases among adults aged ≥45 years in China, 2011-2018: a longitudinal study Community Dent Oral Epidemiol 2021 12 49 6 533 542 10.1111/cdoe.12692 34558095 Kailembo A Preet R Stewart Williams J Common risk factors and edentulism in adults, aged 50 years and over, in China, Ghana, India and South Africa: results from the WHO Study on global AGEing and adult health (SAGE) BMC Oral Health 2016 07 27 17 1 29 10.1186/s12903-016-0256-2 27465011 10.1186/s12903-016-0256-2 PMC4964081 Li S Guo Y Miao Jonasson J Association between social capital and oral health among adults aged 50 years and over in China: a cross-sectional study BMC Oral Health 2022 03 12 22 1 68 10.1186/s12903-022-02102-8 35279136 10.1186/s12903-022-02102-8 PMC8918312 Li C Yao NA Socio-economic disparities in dental health and dental care utilisation among older Chinese Int Dent J 2021 02 71 1 67 75 10.1111/idj.12600 33616055 S0020-6539(20)36503-5 PMC9275339 Major Figures on 2020 Population Census of China 2021 Beijing, China China Statistics Press 2021 Payne AG Alsabeeha NH Atieh MA Esposito M Ma S Anas El-Wegoud M Interventions for replacing missing teeth: attachment systems for implant overdentures in edentulous jaws Cochrane Database Syst Rev 2018 10 11 10 10 CD008001 10.1002/14651858.CD008001.pub2 30308116 PMC6516946 Kim M Oh B Yoo JW Han D The association between mastication and mild cognitive impairment in Korean adults Medicine (Baltimore) 2020 06 05 99 23 e20653 10.1097/MD.0000000000020653 32502052 00005792-202006050-00090 PMC7306381 Su Y Yuki M Hirayama K Sato M Han T Denture wearing and malnutrition risk among community-dwelling older adults Nutrients 2020 01 05 12 1 151 10.3390/nu12010151 31948104 nu12010151 PMC7020032 Suma S Furuta M Takeuchi K Tomioka M Iwasa Y Yamashita Y Number of teeth, denture wearing and cognitive function in relation to nutritional status in residents of nursing homes Gerodontology 2022 06 39 2 197 203 10.1111/ger.12554 34047382 Kim M Han D Does reduced chewing ability efficiency influence cognitive function? Results of a 10-year national cohort study Medicine (Baltimore) 2022 06 24 101 25 e29270 10.1097/MD.0000000000029270 35758356 00005792-202206240-00013 PMC9276352 Zhang J Li D Gao J Health disparities between the rural and urban elderly in China: a cross-sectional study Int J Environ Res Public Health 2021 07 29 18 15 8056 10.3390/ijerph18158056 34360346 ijerph18158056 PMC8345474 Zhang J Chandola T Zhang N Understanding the longitudinal dynamics of rural-urban mental health disparities in later life in China Aging Ment Health 2023 27 7 1419 1428 10.1080/13607863.2022.2098912 35822456 Su B Li D Xie J Wang Y Wu X Li J Prieto-Alhambra D Zheng X Chronic disease in China: geographic and socioeconomic determinants among persons aged 60 and older J Am Med Dir Assoc 2023 02 24 2 206 212.e5 10.1016/j.jamda.2022.10.002 36370750 S1525-8610(22)00783-6 Liu M Tang W Zhang Y Wang Y Baima Kangzhuo Li Y Liu X Xu S Ao L Wang Q Wei J Chen G Li S Guo Y Yang S Han D Zhao X China Muti-Ethnic Cohort (CMEC) Collaborative Group Urban-rural differences in the association between long-term exposure to ambient air pollution and obesity in China Environ Res 2021 10 201 111597 10.1016/j.envres.2021.111597 34214564 S0013-9351(21)00891-4 van de Rijt LJM Stoop CC Weijenberg RAF de Vries R Feast AR Sampson EL Lobbezoo F The influence of oral health factors on the quality of life in older people: a systematic review Gerontologist 2020 07 15 60 5 e378 e394 10.1093/geront/gnz105 31729525 5568430 Block C König H-H Hajek A Oral health and quality of life: findings from the Survey of Health, Ageing and Retirement in Europe BMC Oral Health 2022 12 15 22 1 606 10.1186/s12903-022-02599-z 36517821 10.1186/s12903-022-02599-z PMC9753255 Lu F Chen Y Yang F Do rural-urban identities affect individuals' health? Evidence from China Inquiry 2022 59 469580221104370 10.1177/00469580221104370 35880848 PMC9340418 Zhang J Xiao S Shi L Xue Y Zheng X Dong F Xue B Zhang C Differences in health-related quality of life and its associated factors among older adults in urban and rural areas Risk Manag Healthc Policy 2022 15 1447 1457 10.2147/RMHP.S373077 35923554 373077 PMC9342693 Chen X Giles J Yao Y Yip W Meng Q Berkman L Chen H Chen X Feng J Feng Z Glinskaya E Gong J Hu P Kan H Lei X Liu X Steptoe A Wang G Wang H Wang H Wang X Wang Y Yang L Zhang L Zhang Q Wu J Wu Z Strauss J Smith J Zhao Y The path to healthy ageing in China: a Peking University–Lancet Commission Lancet 2022 12 400 10367 1967 2006 10.1016/s0140-6736(22)01546-x Olofsson H Ulander EL Gustafson Y Hörnsten C Association between socioeconomic and health factors and edentulism in people aged 65 and older - a population-based survey Scand J Public Health 2018 11 46 7 690 698 10.1177/1403494817717406 28768459 Gülcan F Ekbäck G Ordell S Lie SA Åstrøm AN Inequality in oral health related to early and later life social conditions: a study of elderly in Norway and Sweden BMC Oral Health 2015 02 10 15 20 10.1186/s12903-015-0005-y 25881160 10.1186/s12903-015-0005-y PMC4328709 Delgado-Angulo EK Mangal M Bernabé E Socioeconomic inequalities in adult oral health across different ethnic groups in England Health Qual Life Outcomes 2019 05 17 17 1 85 10.1186/s12955-019-1156-3 31101052 10.1186/s12955-019-1156-3 PMC6525386 China Health and Retirement Longitudinal Study CHARLS 2024-11-06 https://charls.pku.edu.cn/en/ Zhang J Wang Q Hao W Zhu D Long-term food variety and dietary patterns are associated with frailty among Chinese older adults: a cohort study based on CLHLS from 2014 to 2018 Nutrients 2022 10 13 14 20 4279 10.3390/nu14204279 36296962 nu14204279 PMC9608682 The Chinese Longitudinal Healthy Longevity Survey (CLHLS)-longitudinal data (1998-2018) Center for Healthy Aging and Development Studies 2020 2024-11-07 https://opendata.pku.edu.cn/dataset.xhtml?persistentId=doi:10.18170/DVN/WBO7LK Fairlie RW The absence of the African‐American owned business: an analysis of the dynamics of self‐employment J Labor Econ 1999 01 17 1 80 108 10.1086/209914 Fagbamigbe AF Adeniji FIP Morakinyo OM Factors contributing to household wealth inequality in under-five deaths in low- and middle-income countries: decomposition analysis BMC Public Health 2022 04 15 22 1 769 10.1186/s12889-022-12988-2 35428294 10.1186/s12889-022-12988-2 PMC9013135 Yuan L Zhao Z Wang J Du M Xiao Y Liu L Sun J Decomposition and comparative analysis of the prevalence of and factors associated with smoking between the rural and urban elderly population in China: a national cross-sectional study Front Public Health 2022 10 824587 10.3389/fpubh.2022.824587 35372230 PMC8968864 Fu X Sun Q Sun C Xu F He J Urban-rural differences in catastrophic health expenditure among households with chronic non-communicable disease patients: evidence from China family panel studies BMC Public Health 2021 05 06 21 1 874 10.1186/s12889-021-10887-6 33957893 10.1186/s12889-021-10887-6 PMC8101026 Yuan L Xu Q Gui J Liu Y Lin F Zhao Z Sun J Decomposition and comparative analysis of differences in depressive symptoms between urban and rural older adults: evidence from a national survey Int Psychogeriatr 2023 02 21 1 12 10.1017/S1041610223000078 36805733 S1041610223000078 Du W Li Y Nie X Li L Tao M Tian X Analysis of the current status and influencing factors of health literacy among the elderly aged 60 to 69 in China Chin J Health Educ 2015 2 31 2 129 132 10.16168/j.cnki.issn.1002-9982.2015.02.008 Li Z Tian Y Gong Z Qian L Health literacy and regional heterogeneities in China: a population-based study Front Public Health 2021 9 603325 10.3389/fpubh.2021.603325 34046382 PMC8144299 Reda SM Krois J Reda SF Thomson WM Schwendicke F The impact of demographic, health-related and social factors on dental services utilization: systematic review and meta-analysis J Dent 2018 08 75 1 6 10.1016/j.jdent.2018.04.010 29673686 S0300-5712(18)30091-5 Qi X Qu X Wu B Urban-rural disparities in dental services utilization among adults in China's megacities Front Oral Health 2021 2 673296 10.3389/froh.2021.673296 35048016 PMC8757718 Reda SF Reda SM Thomson WM Schwendicke F Inequality in utilization of dental services: a systematic review and meta-analysis Am J Public Health 2018 02 108 2 e1 e7 10.2105/AJPH.2017.304180 29267052 PMC5846590 Marcenes W Steele JG Sheiham A Walls AWG The relationship between dental status, food selection, nutrient intake, nutritional status, and body mass index in older people Cad Saude Publica 2003 19 3 809 816 10.1590/s0102-311x2003000300013 12806483 S0102-311X2003000300013 Sheiham A Steele JG Marcenes W Finch S Walls AWG The relationship between oral health status and body mass index among older people: a national survey of older people in Great Britain Br Dent J 2002 06 29 192 12 703 706 10.1038/sj.bdj.4801461 12125796 Moynihan P Varghese R Impact of wearing dentures on dietary intake, nutritional status, and eating: a systematic review JDR Clin Trans Res 2022 10 7 4 334 351 10.1177/23800844211026608 34210202 Mehr K Olszanecka-Glinianowicz M Chudek J Szybalska A Mossakowska M Zejda J Wieczorowska-Tobis K Grodzicki T Piotrowski P Dental status in the Polish senior population and its correlates-results of the national survey PolSenior Gerodontology 2018 12 35 4 398 406 10.1111/ger.12364 30051927 Preisser JS Moss K Finlayson TL Jones JA Weintraub JA Prediction model development and validation of 12-year incident edentulism of older adults in the United States JDR Clin Trans Res 2023 10 09 8 4 384 393 10.1177/23800844221112062 35945823 PMC10504805 Laguzzi PN Schuch HS Medina LD de Amores AR Demarco FF Lorenzo S Tooth loss and associated factors in elders: results from a national survey in Uruguay J Public Health Dent 2016 03 76 2 143 151 10.1111/jphd.12123 26465229 Winkelmann J Rossi JG Schwendicke F Dimova A Atanasova E Habicht T Kasekamp K Gandré C Or Z McAuliffe Ú Murauskiene L Kroneman M de Jong J Kowalska-Bobko I Badora-Musiał K Motyl S Figueiredo Augusto G Pažitný P Kandilaki D Löffler L Lundgren C Janlöv N van Ginneken E Panteli D Exploring variation of coverage and access to dental care for adults in 11 European countries: a vignette approach BMC Oral Health 2022 03 09 22 1 65 10.1186/s12903-022-02095-4 35260137 10.1186/s12903-022-02095-4 PMC8905841 Rezaei S Hajizadeh M Irandoost SF Salimi Y Socioeconomic inequality in dental care utilization in Iran: a decomposition approach Int J Equity Health 2019 10 22 18 1 161 10.1186/s12939-019-1072-5 31640703 10.1186/s12939-019-1072-5 PMC6805463 Oshima K Miura H Tano R Fukuda H Characteristics of individuals in Japan who regularly manage their oral health by having a family dentist: a nationwide cross-sectional web-based survey Int J Environ Res Public Health 2022 08 23 19 17 10479 10.3390/ijerph191710479 36078196 ijerph191710479 PMC9518108 Piedrasanta FC Boyd LD Vineyard J LaSpina L Oral health knowledge, acculturation and utilization of oral health services among a Hispanic and Latino population J Dent Hyg 2021 10 95 5 22 31 34654712 95/5/22 Liu J Chen H Chen Y Li Z Exploring the relationship between migrants' purchasing of commercial medical insurance and urbanisation in China BMC Health Serv Res 2018 09 03 18 1 679 10.1186/s12913-018-3503-1 30176868 10.1186/s12913-018-3503-1 PMC6122700 Islas-Granillo H Borges-Yañez SA Navarrete-Hernández JdJ Veras-Hernández MA Casanova-Rosado JF Minaya-Sánchez M Casanova-Rosado AJ Fernández-Barrera MÁ Medina-Solís CE Indicators of oral health in older adults with and without the presence of multimorbidity: a cross-sectional study Clin Interv Aging 2019 14 219 224 10.2147/CIA.S170470 30787597 cia-14-219 PMC6363395 Wu B Dental service utilization among urban and rural older adults in China -- a brief communication J Public Health Dent 2007 67 3 185 188 10.1111/j.1752-7325.2007.00038.x 17899906