Immigration and Oral Health in Older Adults: An Integrative Approach

Abstract

The aim of this study was to develop an integrative framework on aging, immigration, and oral health. The methodology was a critical review that used immigration as a social determinant framework through which to evaluate its impact on the oral health of older immigrants. We reviewed recent empirical evidence on factors related to oral health in older immigrants. In a systematic search across multiple databases, we identified 12 eligible studies in this review. Among the eligible studies, most were conducted among East Asian immigrants (8 articles), followed by non-Hispanic White/European origin (2 articles), Mexican origins (1 article), and Iran and other Middle East regions (1 article). The research revealed knowledge gaps in the evidence base, including the dynamic relationship between acculturation and oral health, the role of environmental factors on oral health for immigrants, psychosocial stressors and their relationship with oral health, and oral health literacy, norms, and attitude to dental care utilization and oral hygiene practices. The development of the integrative framework suggests the pathways/mechanisms through which immigration exerts influences on oral health in later life. This provides opportunities for researchers, practitioners, and policy makers to gain greater insights into the complex associations between immigration and oral health among older adults.

Introduction

Improving oral health in older immigrants is a global public health concern. Oral health problems and diseases accumulate across the life span, and the prevalence of these problems is particularly high in older adults (Dye et al. 2007). The number of international migrants globally reached 272 million in 2019, a 51-million increase since 2010 (United Nations [UN] 2019b). Immigrant populations are aging; in 2019, there were approximately 32 million migrants aged 65 or older globally (UN 2019a). The increasing number of older immigrants poses a great need to study oral health in this population. Immigrants are a unique segment of the aging population and face a number of challenges that include language barriers, changes in socioeconomic status, decreases or disconnections of their social networks, and cultural adaptation. All of these challenges could negatively affect their ability to achieve good oral health (Liu 2016).

The immigration process refers to individuals landing and living in a new country as immigrants (Rosenzweig et al. 2004). This process is influenced by socioeconomic conditions in communities of origin and the host countries (Berry 1992). Early life conditions, including family socioeconomic status (Cui et al. 2019), living environment (Rouxel et al. 2015), dietary intake (Breda et al. 2019), dental care (Broadbent et al. 2016), and structural factors in their country of origin can largely contribute to the onset and progression of oral health diseases in earlier life prior to their immigration (Fisher-Owens et al. 2007; Halfon et al. 2014; Baker et al. 2018). Compared with those who immigrate early in their lives, individuals who immigrate in later life may be more likely to experience poorer oral health because of an increased risk of linguistic difficulty, cultural barriers, disruptions in employment history, limited retirement income and benefits, and a diminished sense of social standing (Chen et al. 2009; Carr and Tienda 2013).

Large-scale immigration may change the social, economic, and political context (including institutional racism), which will have great impacts on the health care system and health care needs (Shahid and Atkin 2004). Immigration is a process that is both the result of these contextual factors and can also result in changes in risk factors of health at the individual and community levels (Castañeda et al. 2015). Immigration intersects with other factors, such as gender, class, and race (Viruell-Fuentes et al. 2012). These factors are assumed to work together and mutually constituted a complex system of oppression that results in profound health inequality. A growing number of older immigrants globally has resulted in an increased interest in examining oral health status among this population (Aarabi et al. 2018; Jang et al. 2019; Mao et al. 2020; Wu et al. 2020). Developing a conceptual framework to systematically evaluate the impact of immigration on oral health may provide further insights and directions for future policy, research, and practice.

Recognizing common risks between general health and oral health, Watt and Sheiham (2012) extended the social determinants of health framework to oral health. According to this framework, a life course perspective is of relative importance in explaining oral health disparities. It is also proposed that environmental, psychosocial, and behavioral factors are generated within structural determinants (e.g., broader social, cultural, economic, historical, political, and commercial contexts) and that individuals with greater access to a range of resources are less exposed to risk factors of oral health and thus have better oral health outcomes (Watt and Sheiham 2012; Peres et al. 2019). Other theoretical models, for example, behavioral, psychosocial, and materialist, also explain why these identified factors are associated with oral health (Sisson 2007). What is missing in previous theoretical frameworks, though, is a broader understanding of immigration that transcends relations with the larger contextual, community, and individual-level factors.

The objective of this article is to review the empirical evidence on oral health and its related factors among older immigrants and present an innovative conceptual framework that extends the argument proposed by Castañeda et al. (2015), of immigration as a social determinant of health, to oral health. Grounded in the existing literature, we propose to emphasize environmental, psychosocial, and behavioral factors that are closely related to the immigration process, thus, in turn, affecting the relationships between immigration-related factors and oral health. Through the process used in this review, our intention is to produce theoretical advances and offer insights into the complexity of immigration and its impact on oral health, thereby producing directions for future research.

Methodology

This critical review aims to develop an innovative conceptual framework rather than a cursory summary of the empirical evidence (Grant and Booth 2009). Electronic database searches of PubMed, Web of Science, PsycINFO, and CINAHL for studies published from January 1, 2015, to April 15, 2020, were performed (see detailed search terms and results in Supplementary Appendix 1). Reviewing reference lists and hand searching of relevant articles complemented the electronic searches. Inclusion criteria for the search were immigrants aged 50 years and older, oral health outcomes (from clinical examination or self-reported) or oral health–related quality of life as an outcome, empirical studies that examined correlates of oral health outcomes, and peer-reviewed journal articles in English. Exclusion criteria included (1) not empirical studies and (2) studies with mixed-age samples but lacking separate analyses/findings on the population aged 50+ years (see details in Supplementary Appendix 2). Based on previous conceptual frameworks, we grouped the review findings into 4 factors that explain how immigration affects oral health in later life: immigration-related, environmental, psychosocial, and behavioral factors. The results and discussion are presented for each of the 4 factors accordingly.

Brief Summary of Included Studies

We found 12 eligible articles from 4 countries: 9 studies from the United States, 1 from Canada, 1 from Germany, and 1 from Sweden. Ge et al. (2018), Mao et al. (2019), and Mao et al. (2020) used the same data set but investigated different oral health outcomes with different research questions; therefore, we classified them as 3 separate studies. Among the eligible studies, most were conducted among East Asian immigrants (8 articles; Calvasina et al. 2015; Jang et al. 2017; Jung et al. 2017; Ge et al. 2018; Jang et al. 2019; Mao et al. 2019; Wu et al. 2020; Mao et al. 2020), followed by non-Hispanic White/European origin (2 articles; Liu 2016; Aarabi et al. 2018), Mexican origins (1 article) (Garcia et al. 2017), Iran and other Middle East regions (1 article; Olerud et al. 2016; Supplementary Appendix 3: characteristics of the included studies).

Immigration-Related Factors

Theoretical Underpinnings

The immigration process is dynamic and multifaceted, and individuals may migrate from different places of birth, migrate for different reasons, and obtain different immigration statuses. During the immigration process, immigrants also exhibit changes in values, norms, customs, and behaviors when they are exposed to the mainstream culture in the host countries. These changes are defined as “acculturation” (Berry 1992). Acculturation is complex in nature, as it incorporates practices, values, and identifications toward the heritage culture and the receiving culture (Schwartz et al. 2010). Acculturation was also theorized as a predisposing factor of oral health outcomes (Andersen and Davidson 1997).

Current State of Evidence

Immigrants persistently differ in oral health outcomes as compared with native-born populations (Liu 2016; Wu et al. 2020). They have worse oral health outcomes, such as a higher number of decayed teeth (Aarabi et al. 2018) and a higher prevalence of oral diseases and discomfort (Olerud et al. 2016). Current research also addressed how immigration factors, measured by acculturation and its indicators, are associated with oral health in older immigrants, and the findings remain mixed across studies. Indicators of acculturation included length of stay, language proficiency, and behavioral acculturation (i.e., language use, media use, and ethnic social relations). Length of stay was negatively associated with self-reported gum symptoms (Ge et al. 2018) and fair or poor oral health (Jang et al. 2019), whereas it was not correlated with tooth symptoms (Ge et al. 2018) or self-rated oral health (Jang et al. 2017). Behavioral acculturation or English fluency was associated with the diagnosis of periodontitis in one study (Garcia et al. 2017) but not with self-reported oral health and symptoms (Jung et al. 2017; Ge et al. 2018).

Knowledge Gaps and Discussion

Although the literature shows that high-acculturated immigrants demonstrate better oral health outcomes, oral health behaviors, dental care utilization and knowledge (Dahlan et al. 2019), much remains unknown on the dynamic relationship between acculturation and oral health over the course of immigration (Sano and Abada 2019). Most immigrants’ studies focus exclusively on acculturation, and with a relatively narrow focus on language proficiency and length of stay in the host country (Calvasina et al. 2015; Jung et al. 2017; Jang et al. 2019). Moreover, how the immigration process contributes to oral health in later life has not been particularly examined. One area to further explore is the linkage between immigration factors and other factors, including environmental, psychosocial, and behavioral factors, in relation to oral health in older immigrants. Furthermore, one previous theory indicates that these health inequalities—oral health inequalities in particular—may be reduced by adopting healthy cultural practices (Leininger 1997). Implementing culturally targeted oral health promotion programs, which consult directly with ethnic communities, are warranted (Garcia et al. 2017).

Environmental Factors

Theoretical Underpinnings

The materialist explanation stresses the role of environmental factors on oral health (Sisson 2007). Environmental factors such as living situations, working conditions, food availability/security, and neighborhoods are conceptualized as intermediary factors through which socioeconomic and political context contributes to oral health inequalities (Watt and Sheiham 2012). Characteristics of communities or neighborhoods are shown to be linked to various health outcomes (Cagney et al. 2009). The role of neighborhoods/communities is particularly salient as structural determinants of oral health funnel their influences into the local context where individuals reside (Pearlin et al. 2005). Individuals living in structurally and socially disadvantaged neighborhoods may face daily concerns of personal safety and logistical barriers to transportation and access to services, which may lead to the elevated risk of adversity and diminished well-being in the long term (Pearlin et al. 2005).

Current State of the Evidence

Few studies have investigated the relationship between environmental factors and oral health in older immigrant populations. Environmental factors here focus on the local context/environment that individuals live in and have day-to-day contact with. In recent developments of oral health research in older immigrants, only 1 study investigated the neighborhood as an important correlate of oral health. Stronger neighborhood cohesion was related to a lower likelihood of reporting oral health problems among older Chinese American immigrants (Mao et al. 2020). These authors suggested that the protective function of neighborhood cohesion against oral health problems was stronger among older Chinese immigrants living in Chinatown as compared with those living elsewhere.

Knowledge Gaps and Discussion

Environmental factors may include physical and social environments. For instance, social environment (e.g., neighborhood-level socioeconomic status) and physical environment (e.g., proximity to neighborhood resources) influenced oral health outcomes in general American adult populations (Borrell et al. 2006; Finlayson et al. 2010). It is particularly salient to study communities/neighborhoods in immigrant life, as immigrants tend to be separated from their original social and community ties and may face challenges integrating into a new local environment (Liu 2016). However, much remains unknown regarding the role of environmental factors in oral health among immigrants. In addition, the influences of social characteristics of communities/neighborhoods, measured by cohesion, control, and disorder, on oral health outcomes warrants further exploration, especially in older immigrants.

Psychosocial Factors

Theoretical Underpinnings

Psychosocial factors are considered important pathways linking socioeconomic positions with unequal exposure and vulnerability to health damaging conditions and the resulting inequalities in oral health (Watt and Sheiham 2012). For example, stressors are a prominent concept in the psychology literature that hinges upon the dynamic and evaluative relationship between the person and the environment; coping, as a method of changing cognitive and behavioral efforts, is used to address the problem with the environment that is causing stress (problem-focused coping) and/or manage the emotional response to such a problem (emotion-focused coping; Lazarus and Folkman 1984). Stressors include various factors that may induce stress on individuals. Racial discrimination affects an individual’s health outcomes and access to health care. There are multiple levels of racisms and 3 main mechanisms linking racism with inequities in society and health, including cultural racism, institutional racism, and individual-level discrimination (Williams et al. 2019). We focused on individual-level racial discrimination as a part of psychosocial stressors. Racial discrimination has psychological ramifications (Anderson 2013; Stanley et al. 2019). Perceived racial discrimination, reinforced by institutional racism, is known to be harmful to one’s mental health, physical health, and oral health (Lawrence et al. 2016; Stanley et al. 2019; Williams et al. 2019). Ageism and perceived age discrimination can be seen in age-based rationing in clinical decisions, in interpersonal interactions, in organizational cultures, and in health policies (São José et al. 2019). Older immigrants are particularly vulnerable because of accumulative disadvantages and discriminatory experiences related to race, ethnicity, gender, and age in a life course perspective (Pearlin et al. 2005; Dolberg et al. 2018). On the other hand, resilience is an important positive psychological concept in the study of the aging process, as it reflects a phenomenon or process in which positive adaptation occurs in the presence of stress, adversity, or trauma (Tomás et al. 2012). Similarly, the role of social relationships has been widely recognized in health research. Social relationships include social isolation, social integration, quality of relationships, and social networks and social support (Berkman et al. 2000; Umberson and Montez 2010).

Current State of the Evidence

The role of psychosocial factors in oral health remains understudied, especially in older immigrants. Psychosocial factors may include stressors faced by individuals and resources to deal with such stressors. Three recent studies examined the influences of perceived stress, perceived discrimination, resilience, and social support/network on oral health outcomes in this population. In terms of psychosocial stressors, having more perceived stress was associated with a higher likelihood of reporting oral dryness among older Chinese Americans (Mao et al. 2019), whereas the experience of discrimination due to ethnicity, culture, race/skin color, language/accent, or religion was associated with more self-reported dental problems over time among Canadian immigrants (Calvasina et al. 2015). In terms of psychosocial resources, resilience was associated with a higher likelihood of reporting good self-rated oral health in older Chinese Americans (Wu et al. 2020). Support from friends was associated with a lower likelihood of reporting oral dryness among older Chinese Americans (Mao et al. 2019). Having no relatives in Canada was associated with increased oral health problems over time among Canadian immigrants; however, the association was not significant after controlling for covariates (Calvasina et al. 2015).

Knowledge Gaps and Discussion

Despite increasing research on psychosocial factors of oral health, little remains known in older immigrant populations. Psychosocial stressors such as stress, fear, depression, anxiety, and diminished self-esteem have been reported in relation to oral health in later life (Martins et al. 2011; Mao et al. 2019). Older immigrants are especially susceptible to poor oral health and high oral health needs due to acculturative stress, lack of social support, and stigma related to social assistance in accessing dental care (Hoang et al. 2019). How psychosocial stressors are related to oral health largely remains unanswered. On the other hand, psychosocial resources measured by resilience, social support, and social networks are shown to be protective in this population (Calvasina et al. 2015; Mao et al. 2019; Wu et al. 2020). Besides direct relationships between psychosocial resources and oral health outcomes, how such resources interact with other factors toward promoting oral health stays uncharted. For instance, self-efficacy, or the degree of confidence individuals have in their ability to perform certain behaviors, has been theorized as a psychological pathway via which social support exerts influences on health outcomes (Berkman et al. 2000). Inquiries along this line could help explicate the underlying mechanisms linking psychosocial stressors, resources, and oral health in older immigrants.

Behavioral Factors

Theoretical Underpinnings

The relationship between behavioral factors and oral health are grounded in behavioral explanation. This explanation stresses the role of behaviors (health behaviors, oral hygiene practices, and dental care utilization) on oral health outcomes (Sisson 2007). Although oral health knowledge/literacy, cultural norms, beliefs, and attitudes are arguably not behavioral factors per se, they are closely related to behavioral factors. According to cultural explanation and the theory of planned behavior, oral health knowledge/literacy, cultural norms, beliefs, and attitudes strongly affect individuals’ behavior (Sisson 2007; Buunk-Werkhoven et al. 2011).

Current State of the Evidence

Very few empirical studies have been conducted to examine how oral hygiene behaviors contribute to oral health in this population. The only study found in this review shows that among older Mexican Americans, the lack of having a usual source of health care and never flossing were significantly associated with periodontitis status (Garcia et al. 2017). There are inconsistent findings from a limited number of studies addressing oral health behaviors in this population. Current smoking status was not significantly associated with poor oral health among older Chinese (Mao et al. 2020; Wu et al. 2020), whereas it was associated with a higher likelihood of reporting tooth symptoms and periodontitis among older Chinese Americans and Mexican Americans, respectively (Garcia et al. 2017; Ge et al. 2018). Healthy dietary practices, such as eating vegetables daily, were associated with a lower likelihood of reporting oral health problems among older Chinese Americans (Wu et al. 2020).

Pertinent to the immigration process, relatively abundant studies have examined how cultural beliefs and norms shape oral hygiene practice and dental care use in various countries. Many Albanian American immigrants considered oral health important; 87% had annual dental visits, and 95% rated their oral health as good/excellent (Rota et al. 2019). Older immigrants in Sweden were more likely to continue using traditional cleaning methods such as chewing sticks (Olerud et al. 2018), whereas they were less likely to perform frequent toothbrushing and use additional oral hygiene aids than their native-born equivalents (Olerud et al. 2016). Older immigrants were less likely to use preventive dental services and were more likely to have unmet needs and treatment preferences (Olerud et al. 2016; Wilson et al. 2016; Erdsiek et al. 2017; Jang et al. 2017; Aarabi et al. 2018; Jang et al. 2019; Zhang et al. 2019)

Knowledge Gaps and Discussion

Despite the theoretical notions to recognize behavioral factors in oral health, knowledge gaps persist. Behavioral factors other than oral hygiene practice and dental care use are underconsidered in immigrant oral health research, especially in later life. For instance, how health behaviors, including diet/eating, smoking, and drinking are associated with oral health among older immigrants remains unclear, and how health behaviors may interact with oral hygiene practice and dental care use toward oral health warrants further exploration. Individuals’ oral health behaviors and outcomes are subject to the influences of attitudes, beliefs, and subjective norms (Sisson 2007; Buunk-Werkhoven et al. 2011). However, no studies have examined how cultural norms, beliefs, attitudes, knowledge, and literacy influence health behavioral and oral health in older immigrants. Such factors warrant attention in oral health research and practice among older immigrants.

An Integrative Framework of Immigration, Aging, and Oral Health

Based on the review of the current literature, we proposed an integrative framework of immigration, aging, and oral health to explicate how immigration affects oral health in later life (Fig.).

Figure.

Integrative framework of immigration, aging, and oral health.

In this framework, the immigration process is situated within the life course and within the larger structures and contexts (e.g., Andersen and Davidson 1997; Sisson 2007; Watt and Sheiham 2012; Castañeda et al. 2015; Peres et al. 2019). We acknowledge immigration as a crucial part of the larger context in studying immigrant oral health and recognize immigration as a dynamic process that may interact with various aspects in the lives of older immigrants. This framework captures multilevel factors, including structural- and contextual-level factors, community-level factors, and individual-level factors, as well as interactions and pathways across these factors and processes. This framework starts with preimmigration antecedents, including early life conditions before immigration and characteristics in the country of origin (e.g., socioeconomic development, health care system, and quality of education). Individual characteristics include factors related to demographics, socioeconomic status, biological and genetic factors, and physical and cognitive health.

Immigration factors characterize the immigration process and capture the important factors and changes that occur during the exposure to different cultures and environments. These are environmental, psychosocial, and behavioral factors that reflect cultural values, social norms, and health beliefs that are particularly relevant to immigration. Environmental factors focus on the social and physical environment, communities, and neighborhoods that individuals live in and their access to dental care and the quality of such care within the local context. Psychosocial factors shed light on psychosocial vulnerabilities and related protective mechanisms in relation to oral health. Behavioral factors integrate oral health–related behaviors and the underlying cognitive processes, including knowledge, literacy, cultural norms, beliefs, and attitudes.

Directions for Future Research

Several major methodological concerns need to be addressed while conducting research on aging immigrant populations. There is currently a limited number of large longitudinal cohort studies available to study oral health in older adults and even fewer available for older immigrants. The sample size for country-specific older immigrants is usually very small in large national studies, which makes it difficult to conduct meaningful analyses. Even for studies that are designed for immigrant populations, there is a dearth of information on some key measures, such as contextual and structural factors, which are presented in the Figure. Although oral health status from clinical examinations is commonly considered a gold standard, the inclusion of dental clinical examinations in large cohort studies is costly and may not be feasible. Self-reported oral health and oral health symptoms are important indicators of oral health and strong predictors of dental care utilization. It is critical to develop more self-reported oral health and oral health–related quality of life scales to be used in large cohort studies. Overall, having more immigration-specific information and culturally competent measures over the life course is essential for the evaluation of pathways and mechanisms between immigration and oral health.

As illustrated in the proposed framework (Fig.), myriad factors exert influences on immigrants’ oral health over the life course. Some areas of research are particularly needed in the future. First, how early childhood experiences and life conditions before immigration influence oral health remain unanswered. Early life conditions may be directly or indirectly associated with oral health in older immigrants, and different mechanisms may be tested to discern the effects of early life conditions on oral health within the immigration context in later life. We are aware that when participants are older adults, information on early life conditions is usually collected retrospectively. This may result in recall bias in the measures of early life conditions. Second, immigration is a unique experience. It is imperative to examine how specific circumstances that took place before and during the immigration process contribute to oral health in older immigrants. Third, perceived age and race discrimination continue to perpetuate in the life of an older adult. The underlying mechanisms or pathways through which such psychosocial factors influence oral health in older immigrants warrant further exploration. Resilience and coping strategies are crucial in counteracting the negative influences of life stressors, and it is particularly important to examine how these psychosocial resources could protect against poor oral health in older immigrant populations. Fourth, there is a need to examine how cultural factors such as oral health literacy, norms, and attitude affect dental care utilization and oral hygiene practice, which in turn influence oral health status. Finally, it would be informative to study country- and local-level health care systems and health care and immigration policies that affect access to care and oral health status among immigrant populations.

An Integrative Approach to Improve Oral Health in Older Immigrant Populations

The integrative framework proposed in this review will provide guidance regarding the comprehensive examination of the pathways and mechanisms between immigration and oral health in older adults. Furthermore, it highlights the importance of interdisciplinary collaboration in improving the oral health of older adults. Maintaining good oral health is a critical component of healthy aging. This review will assist in the development of integrated models of care and the promotion of oral health throughout the life span.

Author Contributions

B. Wu, contributed to conception, design, data acquisition, analysis, and interpretation, drafted and critically revised the manuscript; W. Mao, Y. Pei, contributed to conception, design, data analysis, and interpretation, drafted and critically revised the manuscript; X. Qi, contributed to design, data acquisition, analysis, and interpretation, drafted and critically revised the manuscript. All authors gave final approval and agree to be accountable for all aspects of the work.