Income inequality in the United States and its potential effect on oral health

Social determinants of health linked with oral health in a representative sample of U.S. adults

BACKGROUND

Oral diseases remain a significant public health problem worldwide, with growing gaps in oral health status among various socioeconomic groups. The objective of the current study is to analyze the impact of different social determinants of health (SDOH) on oral health outcomes (frequency of dental visits, self-reported oral health status, embarrassment because of oral health status, and tooth loss) among a representative sample of United States (U.S.) adults.

METHODS

Cross-sectional data for this observational study came from adults aged 18 and above (N = 5,320) participating in the nationally representative 2021 State of Oral Health Equity in America survey. Bivariate and multivariable analyses were conducted to examine the associations between oral health outcomes (dependent variables) and SDOH independent variables: structural (race/ethnicity, income, education); and intermediary (lack of transportation, food insecurity, racial discrimination, and housing instability), controlling for the confounding variables of age, gender, employment status, dental insurance, self-rated mental/emotional health, self-rated physical health, presence of one or more chronic conditions, and having had a routine physical examination in the past year.

RESULTS

When controlling for confounding variables, Black adults were less likely than White adults to have had a dental visit in the last year (odds ratio (OR) = 0.72 (95% confidence interval (CI) = 0.57-0.92, p < 0.05), more likely to report feeling self-conscious or embarrassed due to their oral health (OR = 1.67 (95% CI = 1.31-2.12, p < 0.05), and more likely to have at least one permanent tooth removed (OR = 1.67 (95% CI = 1.31-2.13, p < 0.05). Higher income and more education were significantly associated with greater odds of rating one's oral health positively and having had a dental visit in the past year and lesser odds of feeling self-conscious or having at least one tooth removed (p's < 0.05). All four intermediary determinants were associated with significant (p < 0.05) and negative odds of having a dental visit in the past year and reporting positive oral health, and with positive odds of having at least one permanent tooth removed. The odds of feeling self-conscious or embarrassed due to their oral health were significantly and positive associated with all intermediary determinants except for racial discrimination (OR = 1.21, 95% CI = 1.00-1.46).

CONCLUSIONS

Significant inequities still exist in the U.S. regarding SDOH and their relationship to oral health. Improving oral health will involve addressing SDOH. Successful policy and public health interventions must address not only structural factors but also intermediary SDOH.

Science-Informed Health Policies for Oral and Systemic Health

Oral, dental and craniofacial (ODC) health has a profound impact on general health and welfare throughout life, yet US dentists and physicians operate across misaligned silos. This protracted division limits access to optimal health, supports fee for services, and exacerbates health disparities. Early in the 20th century, the most frequent dental therapy was tooth extraction: removed infected teeth were substituted by prosthetic appliances - commonly, dentures or nothing. Most adults assumed becoming edentulous was a normal corollary of aging. With the discovery of penicillin and other antibiotics, healthcare professionals and policy makers predicted infectious diseases would become irrelevant. However, given numerous health threats, including SARS-CoV-2, HIV, multidrug-resistant bacteria, Zika virus, Ebola virus, and now monkeypox, public and professional awareness of transmissible infectious diseases has never been more evident. Ironically, little attention has been paid to unmet transmissible, infectious, common oral diseases - dental caries and periodontal diseases. Therefore, these persist within "the silent and invisible epidemic". The preventable death of a young boy in 2007 from an infected untreated tooth that produced bacterial meningitis is a profound reminder that our nation has vast inequities in education, health, and welfare. The impact of oral infections on hospital-acquired pneumonia, post-operative infection in cardiac valve surgery, and even academic performances of disadvantaged children displayed through sociodemographic characteristics and access to care determinants also are profound! This paper asserts that current and emerging ODC health knowledge and science will inform health policies and advance equity in access to care, affordable costs, and optimal healthcare outcomes. We recommend that legal and regulatory systems and public health programs be required to ensure health equity. A fair healthcare system that addresses holistic healthcare must be transparent, accessible, integrated and provide a standard of oral healthcare based upon scientific evidence for all people across the lifespan.

Unemployment and expenditure on health and education as mediators of the association between toothbrushing and global income inequalities

Objective

The study assessed the association of country-level income inequalities with the percentage of schoolchildren toothbrushing-at-least-twice-daily; and the mediating effect of country-level unemployment rate and governmental expenditure on health and education (EH&E).

Methods

This was an ecological study. The dependent variable was country-level toothbrushing-at-least-twice-daily among 11-15-year-old schoolchildren. Data for the period 2009 to 2019 were extracted from two global surveys about schoolchildren’s health and from manuscripts identified through a systematic search of three databases. The independent variable was country-level income inequalities measured by the Gini coefficient (GC) extracted from the Sustainable Development Report 2021. The mediators were the unemployment rate and EH&E. We stratified the sample by the level of GC and assessed the correlation between the dependent and independent variables in each stratum. Linear regression was used to assess the relations between the dependent and independent variables, and mediation path analysis was used to quantify the direct, indirect, and total effects.

Results

Data were available for 127 countries. The mean (SD) percentage of children who brushed-at-least-twice-daily was 67.3 (16.1), the mean (SD) GC = 41.4 (8.2), unemployment rate = 7.5 (4.7) and EH&E = 8.4 (3.3). The percentage of children brushing at-least-twice-daily had weak and non-significant correlation with GC that was positive in countries with the least inequality and negative for countries with higher levels of inequality. A greater percentage of schoolchildren brushing-at-least-twice-daily was significantly associated with higher GC (B = 0.76, 95%CI: 0.33, 1.18), greater EH&E (B = 1.67, 95%CI: 0.69, 2.64) and lower unemployment rate (B=-1.03, 95%CI: -1.71, -0.35). GC had a significant direct positive effect (B = 0.76, 95%CI: 0.33, 1.18), a significant indirect negative effect through unemployment and EH&E (B=-0.47, 95%CI: -0.79, -0.24) and a non-significant total positive effect (B = 0.29, 95%CI: -0.09, 0.67) on the percentage of schoolchildren brushing-at-least-twice-daily.

Conclusion

Unemployment and EH&E mediated the association between income inequality and toothbrushing. Country-level factors may indirectly impact toothbrushing.

Determining the factors associated with oral health-related quality of life in Chinese elders: Findings from the fourth national survey

OBJECTIVE

The purpose of this study was to assess the associations between the self-reported oral health-related quality of life (OHRQoL) of older Chinese people and their socio-economic status and oral health using data collected in the 4th National Oral Health Survey.

METHODS

After multistage stratified cluster sampling, 4332 adults aged 65-74 years participated in the study. After a clinical examination, the participants completed a structured questionnaire. A Mandarin version of the General Oral Health Assessment Index (GOHAI) was included in the questionnaire. Clinical examinations were carried out using the criteria recommended by the World Health Organization. Multivariate analysis was used to evaluate the associations of the clinical and socio-demographic variables with the GOHAI scores of the participants.

RESULTS

The weighted mean (SE) GOHAI score was 51.6 (0.0). Female sex and having more than 10 missing teeth, unrestored tooth spaces, more than 10 decayed teeth and a periodontal pocket ≥6 mm were negatively associated with the GOHAI score, while having a higher education level and living in the Eastern region of China were positively associated with the GOHAI score.

CONCLUSION

After adjustment for confounders, the OHRQoL of older Chinese individuals was mainly affected by untreated dental caries and the loss of teeth. Older Chinese individuals who were male, had a higher education level, were from the Eastern region, had no unrestored tooth spaces or deep periodontal pockets and had fewer decayed or missing teeth had higher GOHAI scores, indicating better OHRQoL.

Association between Medicaid expansion, dental coverage policies for adults, and children's receipt of preventive dental services

OBJECTIVE

To examine whether low-income children's use of preventive dental services is linked to variation in state Medicaid policies that affect parents' access to dental care in Medicaid.

DATA SOURCES

Medical Expenditure Panel Survey (2011-2016), Area Health Resources File, and Medicaid adult dental coverage policies.

STUDY DESIGN

We conducted a quasi-experimental analysis using linked parent-child dyads in low-income families (≤125 percent of the Federal Poverty Level). We assessed whether expansions of Medicaid to low-income adults under the Affordable Care Act were associated with increases in the use of preventive dental services among low-income children when state Medicaid programs did vs did not cover these services for adults.

PRINCIPAL FINDINGS

Over the study period, 37.8 percent of low-income children received at least one annual preventive dental visit. We found no change in children's receipt of preventive dental care associated with Medicaid expansions in states that covered (1.26 percentage points; 95% CI: -3.74 to 6.27) vs did not cover preventive dental services for adults (3.03 percentage points; 95% CI: -2.76 to 8.81). (differential change: -1.76 percentage points; 95% CI: -8.09, 4.56). However, our estimates are imprecise, with wide confidential intervals that are unable to rule out sizable effects in either direction.

CONCLUSION

We did not find an association between Medicaid expansions with concurrent coverage of preventive dental services for adults and children's use of these services. Factors other than parental access to dental benefits through Medicaid may be more salient determinants of preventive dental care use among low-income children.

Dental expenditure, progressivity and horizontal inequality in Chinese adults: based on the 4th National Oral Health Epidemiology Survey

Background

The financial burden of oral diseases is a growing concern as the medical expenses rise worldwide. The aim of this study was to investigate the dental expenditure, analyze its progressivity and horizontal inequality under the general health finance and insurance system, and identify the key social determinants of the inequality for Chinese adults.

Methods

A secondary analysis used the data of 13,464 adults from the 4th National Oral Health Epidemiological Survey (NOHES) in China was undertaken. The dental expenditure was collected and divided into out-of-pocket and health insurance payments. Horizontal inequality index and Kakwani index were used to analyze the horizontal inequality and progressivity, respectively. The decomposition model of the concentration index was set up to explore the associated socioeconomic determinants.

Results

The results showed that a mean dental expenditure per capita of Chinese adults was $20.55 (95% Confidence Interval-CI: 18.83,22.26). Among those who actually used dental service, the cost was $100.95 (95%CI: 93.22,108.68). Over 90% of dental spending was due to out-of-pocket expenses. For self-reported oral health, the horizontal inequality index was − 0.1391 and for the decayed tooth (DT), it was − 0.2252. For out-of-pocket payment, the Kakwani index was − 0.3154 and for health insurance payment it was − 0.1598. Income, residential location, educational attainment, oral hygiene practice, self-reported oral health, age difference were the main contributors to the inequality of dental expenditure.

Conclusion

Dental expenditure for Chinese adults was at a lower level due to underutilization. The ratio of payments of dental expenditure and utilization was disproportional, whether it was out-of-pocket or insurance payment. Individuals who were more in need of oral care showed less demand for service or not required service in time. For future policy making on oral health, it is worth the effort to further promote the awareness of the importance of oral health and utilization of dental service.

The Relationship between Income and Oral Health: A Critical Review

In this critical review, we summarized the evidence on associations between individual/household income and oral health, between income inequality and oral health, and income-related inequalities in oral health. Meta-analyses of mainly cross-sectional studies confirm that low individual/household income is associated with oral cancer (odds ratio, 2.41; 95% confidence interval [CI], 1.59-3.65), dental caries prevalence (prevalence ratio, 1.29; 95% CI, 1.18-1.41), any caries experience (odds ratio, 1.40; 95% CI, 1.19-1.65), tooth loss (odds ratio, 1.66; 95% CI, 1.48-1.86), and traumatic dental injuries (odds ratio, 0.76; 95% CI, 0.65-0.89). Reviews also confirm qualitatively that low income is associated with periodontal disease and poor oral health-related quality of life. Limited evidence from the United States shows that psychosocial and behavioral explanations only partially explain associations between low individual/household income and oral health. Few country-level studies and a handful of subnational studies from the United States, Japan, and Brazil show associations between area-level income inequality and poor oral health. However, this evidence is conflicting given that the association between area-level income inequality and oral health outcomes varies considerably by contexts and by oral health outcomes. Evidence also shows cross-national variations in income-related inequalities in oral health outcomes of self-rated oral health, dental care, oral health-related quality of life, outcomes of dental caries, and outcomes of tooth loss. There is a lack of discussion in oral health literature about limitations of using income as a measure of social position. Future studies on the relationship between income and oral health can benefit substantially from recent theoretical and methodological advancements in social epidemiology that include application of an intersectionality framework, improvements in reporting of inequality, and causal modeling approaches. Theoretically well-informed studies that apply robust epidemiological methods are required to address knowledge gaps for designing relevant policy interventions to reduce income-related inequalities in oral health.

Oral Health Disparities Across the Life Span

Despite improvements in the oral health status of the US population as a whole, a disproportionately higher burden of oral diseases and disorders are borne by those individuals from low-income and racial and ethnic minority groups. These differences in health status, health outcomes, or health care use between distinct socially disadvantaged and advantaged groups are well documented and known as health disparities. It is vital that members of the dental profession understand the distribution of oral health and disease across different populations and the life span and participate in developing innovative and sustainable approaches to eliminate oral health disparities.