Oral health literacy and oral health outcomes among older people: a cross-sectional study (2025)

Background

Oral health literacy (OHL) might have an impact on oral health outcomes. Currently, relatively few related studies have been conducted among older people. The aim of this study was to explore the impacts of OHL on oral health outcomes in older adults in a cross-sectional design.

Methods

From November to December 2023, through the utilization of the cluster sampling approach, a questionnaire survey was carried out among elderly patients visiting the Prosthodontics Department of West China hospital of Stomatology. Data were collected through the general information questionnaire, the Chinese version of the Oral Health Literacy Scale, the Geriatric Oral Health Assessment Index, and oral examinations. Descriptive statistics, binary logistic regression, and poisson regression were used to analyse the data.

Results

A total of 407 valid questionnaires were recovered, with an effective retrieval rate of 98.79%. After adjustment for sociodemographic, economic and oral health behaviours, the results of the binary logistic regression indicated that the correlations between OHL and self-rated oral health were not statistically significant, while OHL was a predictor variable for dental expenditures within the past year (OR = 0.591; 95%CI: 0.371–0.939), and the poisson regression revealed that OHL was a predictor variable of the quality of life (PR = 1.062, 95%CI: 1.030–1.084) and the number of lost teeth (PR = 0.917, 95%CI: 0.865–0.972).

Conclusions

This study showed that OHL was closely associated with recent dental expenditure, oral health-related quality of life and the number of lost teeth. These findings could contribute to the planning and development of oral health education programs aimed at enhancing the OHL among the elderly population.

The global population is experiencing an unprecedented rate of ageing. According to data from the World Health Organisation (WHO), in 2022, the global population of people aged 65 or over was 771 million [27], and by 2030, 1 in 6 people in the world will be 60years or over [25]. In China, by 2022, the country's elderly population aged 60years and older had reached 280.04 million, accounting for 19.8% of the total population [7]. Maintaining good physical health is essential for the elderly to fully appreciate their later years.

Good oral health is recognised as a crucial factor in healthy ageing and has been associated with better general well-being, as well as reduced morbidity and mortality among the elderly [9, 20]. However, the oral health of elderly people around the world is far from optimistic. The research findings indicate that the global prevalence of dental caries among individuals aged 65–74 is reported to be 48% [6]. According to the WHO, approximately 22.7% of people over the age of 60 worldwide suffer from edentulism. The estimated burden of disability-adjusted life years (DALYs) due to tooth loss exceeds 9.5 million [26]. In China, the prevalence of dental caries among individuals aged 65–74 has reached 98% [8], with a prevalence of complete edentulism at 4.5%, an average of 22.5 remaining teeth, and a replacement rate for lost teeth of 63.2% [8, 28]. Therefore, the oral health problems of the elderly should not be ignored.

Self-rated oral health (SROH), oral health-related quality of life (OHRQoL), the number of lost teeth and dental expenditures are often used by researchers as measures of oral health outcomes [2, 16, 26]. SROH and OHRQoL have been recommended as two frameworks that can help dentists assess how poor oral health can affect people's well-being [2]. Tooth loss is one of the signs of poor oral health among the elderly population [16]. Dental expenditures may result in productivity losses. In 2019, the total amount of productivity losses caused by oral diseases worldwide reached approximately 323 billion US dollars [26]. What factors influence these indicators? More research is warranted.

Oral health literacy (OHL) refers to an individual's capacity to obtain, process and understand fundamental health information and services essential for making appropriate oral health decisions [18, 21]. Studies have shown that OHL may be associated with oral health outcomes [1,2,3,4, 13, 15, 17, 19]. Some studies have demonstrated a correlation between OHL and SROH [15, 19], while the investigation conducted by Bado et al. concluded that there is no discernible association between the two [2]. Therefore, further research is necessary. Furthermore, the correlation between OHL and dental expenditures has rarely been reported in studies; and there are also few studies on OHL in the elderly population and those of the elderly in China. The purpose of the study was to examine the impacts of OHL on oral health outcomes among elderly people in China.

The report followed Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) Statement guidelines (Table S1).

Study design and participants

We used a descriptive cross-sectional study design with cluster sampling, and collected information about OHL and oral health outcomes in older adult patients seeking care at the Prosthodontics Department of West China hospital of Stomatology. Data were collected from November to December 2023.

Eligible participants were invited to participate in this study according to the selection criteria. Inclusion criteria: full conscious awareness, agreement to participate in the investigation, and an age of 60years or older; Exclusion criteria: an inability to communicate normally due to hearing impairment.

We calculated the sample size according to the pre-experimental results of this study. In this study, the mean (standard deviation) of the OHL score was 42.32 (9.369). PASS15 software was used to estimate the sample size, and the calculation formula was N = (u_ασ/δ)², the minimum sample size required was 340 participants. Taking into account the 20% dropout rate, the sample size was calculated as 408 cases.

Instruments

The instruments consisted of general information questionnaire, the Chinese version of the Oral Health Literacy Scale, the Geriatric Oral Health Assessment Index, and oral examinations.

The general questionnaire was designed with reference to the Adult Questionnaire of the Fourth National Oral Health Epidemiological Survey in China [28]. In this questionnaire, we examined sex, age, educational level, purchasing insurance, family income, smoking status, alcohol consumption, frequency of teeth brushing, SROH, and dental expenditure. Sex was classified as “Male” and “Female”. Age was filled by the participant in accordance with his or her own age. According to the highest level of education completed, education was categorized as “Technical secondary school or college degree”, and “Bachelor degree and above”. Purchasing insurance was identified using the question: “Do you have the following medical insurance?” The response options were the following: “basic medical insurance for urban workers,” “basic medical insurance for urban residents,” “new rural cooperative medical care,” “commercial insurance,” and “free medical service.” The family income variable was determined based on the family's annual total income, which was divided into “0.01–4.99,” “5–9.99,” “10–14.99,” “15–19.99,” and “ ≥ 20” 10,000 yuan. Smoking status was classified as “current smoker,” “never smoker,” or “former smoker.” Alcohol consumption was categorized as “drinker,” “never drinker,” and “former drinker.” The frequency of teeth brushing was evaluated based on the following question: “How often do you brush your teeth?” The response options were as follows: “ ≤ 1 times/day” and “ ≥ 2 times a day”. SROH is an effective, simple and subjective tool for self-perceived oral health assessment, providing insight into patients' overall evaluation of their oral health [14]. It was evaluated using a single question “How do you rate the condition of your teeth and mouth?” Response options were dichotomized into “very poor”, “poor”, “neither good nor poor”, “good”, and “very good” [14]. Dental expenditure in the past year was determined by answering “no” or “yes”. For the elderly who chose “yes”, they would then fill in the specific amount.

We assessed OHL using the Chinese version of the short form Health Literacy in Dentistry scale (HeLD-14). This scale contains 14 items and is used to appraise seven dimensions (communication, understanding, receptivity, utilization, support, financial, and access) [11, 30]. The response options were recorded using a 5-point Likert scale, ranging from “unable to do” (score 0) to “without any difficulty (score 4)”. Sum scores ranged from 0 to 56, with higher values indicating better OHL. The Cronbach's α of the Chinese version of Held-14 was 0.908, and both the construct validity and discriminant validity demonstrated excellent results [30].

OHRQoL was assessed using the Geriatric Oral Health Assessment Index (GOHAI), which consists of 12 items and includes three dimensions: physical functioning, pain and discomfort, and psychosocial functioning [24]. Each item is scored on a 5-point Likert scale, with “very often”, “often”, “sometimes”, “rarely” and “none”, scoring 1, 2, 3, 4 and 5 points respectively. Sum scores ranged from 12 to 60, with higher scores indicating better oral health-related quality of life. The scale demonstrates good reliability (Cronbach's α: 0.81) and validity when applied to Chinese elderly individuals [23].

The number of lost teeth was recorded at the time the participant entered the clinic for an oral examination, with 32 teeth as the base number.

Data collection

Before conducting the investigation, the investigators conducted unified training on the content and methods of questionnaire to improve the homogeneity of the study. When conducting the research, the researcher introduced the purpose and content of the study to the elderly. When the elderly agreed to participate, questionnaires were distributed. The researchers assisted the elderly to fill out the questionnaires on the side, answered the questions raised, etc. When the questionnaires were retrieved, the researcher checked whether the questionnaires were fully filled out. The participants were led to the consulting room for an oral examination and the number of missing teeth was collected.

Statistical analysis

All data were analyzed using IBM SPSS 19.0 statistical software. The normal distribution of the values was evaluated using the Kolmogorov–Smirnov test. For continuous variables, we report median (p25–p75), and for categorical data, we present frequency and percentages. Binary logistic regression and poisson regression were applied to estimate multivariate relationships of OHL and oral health outcomes after adjusting for other covariates.

When SROH and dental expenditures within past year were used as oral health outcome variables, binary logistic regression was adopted. When GOHAI scores and the number of tooth loss were used as oral health outcome variables, Poisson regression was used. Three models were adopted in both analytical methods. In Model 1, sex, age, and education level were considered as covariates. Model 2 adds two covariate contents of purchasing insurance and annual household income on the basis of Model 1. Model 3 incorporates three covariates of oral health related behaviors (smoking status, alcohol consumption, and brushing teeth) to Model 2.

Description of participants

A total of 412 participants completed the survey. However, 5 of them were excluded because they did not meet the age-related inclusion criteria. Eventually, a total of 407 participants were included in the research analysis, with an effective retrieval rate of 98.79%. The proportion of male and female participants who completed the survey was comparable, but there were slightly more women (54.3%). The median (p25–p75) of the age of elderly were 69 (64–77) years. Only 17.7% of the population had a bachelor's degree or higher. The overwhelming majority of the respondents (92.6%) purchased insurance. Approximately two-thirds of the participants (72%) had a household income of less than ¥100,000. Smoking and alcohol consumption were low among the surveyed population, accounting for 15.5% and 11.3%, respectively. Almost two fifths of the participants brush their teeth ≤ 1 time/day (Table1).

In this study, the HeLD-14 score was categorized as “low OHL (< 42)” and “high OHL (≥ 42)” based on a median split [2], and a proportion of 56% of the participants exhibited a high level of OHL. Only 27.8% of the participants claimed that their oral health condition was good or excellent. More than three fifths of individuals (62.7%) have had dental expenditures during the past year. The median (p25–p75) of the GOHAI scores and the number of lost teeth were 47 (38–54) and 12 (6–16), respectively (Table1).

OHL and oral health outcomes of participants

In all binary logistic regression models, the correlations between OHL and SROH were not statistically significant, while OHL was a predictor variable for dental expenditures with past year. In the final model, which included all covariates, there were strong associations between OHL and dental expenditures (odds ratio [OR] = 0.591; 95%CI: 0.371–0.939), as can be seen in Table2.

In all the poisson regression models, OHL was a predictor variable of OHRQoL and the number of lost teeth. In Model 3, when other variables were controlled, there were correlations between OHL and OHRQoL (prevalence ratio, [PR] = 1.062, 95%CI: 1.030–1.084), as well as between OHL and the number of lost teeth (PR = 0.917, 95%CI: 0.865–0.972). Statistical details are showed in Table3.

This study investigated the influence of OHL on oral health outcomes in a sample of Chinese elderly. The findings show that OHL was an important predictor of dental expenditures, OHRQoL, and tooth loss, highlighting the importance of OHL in oral health.

The HeLD-14 scale, developed by Jones et al., was utilized as OHL assessment tool in this study [11]. It has been validated for reliability and validity in Australia, Thailand, Brazil, and China in recent years [2, 11, 17, 29]. This study represents the first of its kind conducted in the Chinese elderly population, providing new evidence for the research of OHL. The median (p25–p75) of the HeLD-14 scores were 42 (32–52), which were lower than the scores of Australian adults [13] and Brazilian adults [2], but higher than those of Thai elders [17]. This might be associated with disparities among countries, populations, etc. The population in this study was the elderly people who visited the restorative dentists. Nearly three-fifths of them had received oral medical treatment within the past year, and such experiences might help improve their OHL. Therefore, their scores were higher than those of the elderly population in Thailand [17]. However, their scores were lower than those of adults in Australia [13] and Brazil [2], which may be related to the different inclusion criteria and study populations.

Our findings demonstrated that there was no statistically significant correlation between OHL and SROH, which was consistent with the research results of Bado et al. [2]. There are also studies showing that low OHL is significantly correlated with poor SROH [12, 29]. This could be associated with the inconsistency of the SROH responses and the calculation methods between the studies. For example, in Jones' study [12], the responses were dichotomised, with those reporting their oral health as “excellent, very good, or good” recoded as “good” and responses of “fair or poor” recoded as “poor”. This is not in line with the current study, thereby deviations might occur as a result.

Our findings revealed that the probability of incurring dental expenses in the past year for people with high OHL was 0.591 times that of those with low OHL, indicating that limited OHL was correlated with higher dental expenses. This is in line with research findings regarding the OHL of caregivers and the oral health-related expenditures of their young children [22]. In future studies, the correlation between OHL and oral health expenditure could be explored further.

The results indicated that OHL was a predictor of OHRQoL. OHRQoL is part of the impact of oral diseases and dental interventions on patients' health-related quality of life [10]. Studies show that limited OHL is associated with worse OHRQoL [2, 4, 11], which is in line with the findings of our study. However, the assessment scales of OHRQoL used in these studies are inconsistent. Therefore, in future studies, the homogeneity of the research can be strengthened.

The findings showed that after adjusted for all covariates, the number of tooth loss among the population with high OHL was 0.917 times that of the population with low OHL. This result was consistent with several previous studies [5, 17], which indicated that participants with adequate OHL had fewer lost teeth than those with inadequate OHL. It is observable that OHL is correlated with the long-term outcome of oral health. One possible explanation is that individuals with adequate OHL are more likely to detect oral diseases earlier and seek necessary treatment in a timely manner compared to those with limited OHL [3].

The main strength of this study is that, to the best of our knowledge, this is the first time where the HeLD-14 scale has been employed in a sample of elderly individuals in China to assess the influence of OHL on oral health outcomes. Although this study might have suggested that OHL served as a predictive variable for some oral health outcomes of the elderly, it still has certain limitations. Firstly, the population surveyed in this study was from a stomatology hospital and was not a good representation of the entire elderly population. Then, among the indicators of oral health outcomes regarding oral diseases, only the number of lost teeth was included, and indicators such as caries and periodontal disease could be added in future studies. Furthermore, it was a cross-sectional survey; therefore, a causal relationship between OHL and oral health outcomes could not be drawn from the present study.

OHL:

Oral health literacy

SROH:

Self-rated oral health

OHRQoL:

Oral health-related quality of life

HeLD-14:

Health Literacy of Dentistry scale

GOHAI:

General Oral Health Assessment Index

Authors and Affiliations

1. State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases &, Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, 610041, People’s Republic of China

   Ju Li,Yanru Chen&Wen Yan

2. State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases &, Department of Nursing, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, 610041, People’s Republic of China

   Fan Liu

3. West China School of Nursing, Sichuan University, Chengdu, Sichuan, 610041, People’s Republic of China

   Wen Yan

Contributions

All the authors contributed to the study design, data analysis, and manuscript preparation. Ju Li and Wen Yan contributed to data collection. Yanru Chen, Wen Yan, and Fan Liu critically revised the manuscript.

Corresponding author

Correspondence to Wen Yan.

Ethics approval and consent to participate

The study was obtained the approval of the Ethics Committee of West China Hospital of Stomatology, Sichuan University (approval number: WCHSIRB-D-2023–319), and adhered to the ethical standards of the Declaration of Helsinki. Informed consents were obtained from all participants. We declare that the questionnaire survey was performed in accordance with the relevant guidelines and regulations.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.

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