In this study, we examined the associations between different aspects of the neighbourhood environment and dental caries experience according to gender and age. The results showed that the regional socio-economic context was linked with caries in men and that the associations between regional contextual variables and dental caries experience differed by age group, consistent with the findings of several previous studies [14, 15]. Although many studies have reported significant effects of the socio-economic context on dental caries experience, most studies have used global proxies, such as rurality or deprivation, to describe the regional socio-economic environment [2, 5–9]. However, recent thinking on the role of social and material environments in generating health inequalities has led to the collection of true ‘area’ data that accurately reflect the character, amenableness, and opportunity afforded by the area or neighbourhood in which people live [16, 17]. In this study, we constructed new regional contextual variables from various socio-economic indices that reflected different aspects of the regions using factor analysis.
Traditionally, the social context has been shown to have a greater influence on women than on men because they spend more time at home looking after children, doing domestic work, or being primary caregivers [18–22]. In contrast, the results of our study indicated that the regional context was relatively beneficial in reducing the prevalence of caries experience in men; however, this effect was weaker than that observed for women. The association between neighbourhood disadvantage and poor health is not always straightforward . Some evidence has suggested that the place of residence may not affect all people in the same way [23–27]. Time spent at home seems an unlikely explanation, given the lack of a substantial gender difference in exposure to the residential environment . Studies that have specifically explored men and women with similar working, social, and material circumstances have shown a reduction in, or the absence of, gender-based morbidity [14, 28]. Indeed, the inconsistency may be due to differences in the conceptualisation and measurement of the social environment. Because we focused primarily on regional factors, such as material, physical, and economic capital, men’s health status could have been more affected by regional context. However, some studies that measured perceived social context, such as social support networks, social capital, social participation, or trust, found that it had a greater influence on women than on men [29–32].
The conceptual distinction between biological sex and social gender is also important in efforts to better understand the oral health difference between men and women. However, the effects of these characteristics may be difficult to disentangle in specific contexts . Gender is a dynamic set of socially constructed relationships embedded in everyday interactions, rather than a simple individual attribute . Many studies have shown that caries experience rates are higher in women than in men [12, 13, 15]. These variations have traditionally been assumed to be biological in origin, but recent work has demonstrated that these effects may be due to multi-factorial behavioural issues involving both sex and gender . Social aspects that require further investigation include gender differences in diet and eating patterns, as well as wider dimensions of inequality between women and men [12, 13, 34].
In this study, we showed that residents of regions with mid-level services and medical facilities had a higher risk of having dental caries experience than did those of regions with the highest level of facilities, after controlling for individual-level variables; in age-stratified analyses, this association was observed only in young adults (19–34 years). Public and private services provided to support people in their daily lives, including medical services, are one of the most commonly proposed regional socio-economic factors that affect the health of residents. However, little evidence is available to support the hypothesis that an increase in a region’s health resources directly affects residents’ health status. McIntyre and Ellaway  conceptualised regional features, including features aggregated in factor II in this study, as ‘opportunity structures’; that is, socially constructed and socially patterned features of the physical and social environments that may promote or damage health, directly or indirectly, through the possibilities they provide for people to live healthy lives. The Korean government is currently collecting small-area dental service statistics, such as dentist- to-population ratios and numbers of clinics, and we expect that studies conducted in the near future will benefit from the use of such statistics.
Residents of regions that were least dependent on manufacturing industries exhibited a significantly higher prevalence of dental caries than those of the most dependent regions. Age-stratified analyses showed a significant association only in the young middle-age group (35–44 years). Socio-economic factors affecting health status could operate positively or negatively, and these factors did not show the same effects in all areas . The positive and negative aspects of the manufacturing industry may directly or indirectly influence individual health status through different mechanisms and magnitudes, according to the degree of dependence. Regarding factor IV, which reflects the affluence of local government, people aged 45–54 years living in regions with mid–low levels of affluence showed a significantly higher risk of dental caries experience, but those in the poorest regions did not. This nonlinear relationship also indicates that the socio-economic factors affecting the health status of residents operate through different mechanisms or degrees, according to geographic location.
The last decade has seen a growing interest in the links among sex, gender, and health, and the importance of these issues has been recognised not only from the perspective of equity, but also as a prerequisite for more effective care . As a result, a large body of evidence based on differences in patterns of morbidity and mortality between women and men has accumulated. However, these issues have received little attention to date in the context of oral health research and practice. The fact that men and women interact with their environment in a different way, and thus are likely to benefit from different types of intervention, may also have important health policy implications. However, further research is needed to gain a more detailed understanding of the social processes underlying these gender health effects .
In this study, age seemed to act as a possible effect modifier of environmental impact on dental caries experience, although this was not obvious from our data. Based on the results of the present study, we suggest that young adults (19–34 years) living in areas with good services and medical facilities were less susceptible to having dental caries experience. Likewise, old middle-aged (45–54 years) people had a higher risk of having dental caries experience if they lived in regions with a financially weak local government. This finding may be because the comprehensiveness of dental health services provided by community health care centres is highly dependent on the financial status of the local government in Korea, and these services are usually used by older people rather than younger individuals, who tend to have less interest in community affairs. A full assessment of this issue requires more clear evidence and the establishment of a causal background. However, these various age-related patterns can provide meaningful information about complex environmental factors that could affect individual dental caries experience by age group in different ways.
This study has some limitations. First, the cross-sectional nature of the data used in this analysis did not allow us to investigate the directionality of the associations or to clarify the time frame of the exposures. Second, we did not measure the length of time that participants had spent in their neighbourhoods or the extent of their exposure to the neighbourhood environment. Third, our use of the combined DMFT index as an outcome in this study did not allow us to separate the proportions of caries, missing, and filled teeth present, which could be affected in different ways by the neighbourhood environment during the study period from that during the subjects’ lives as a whole. Indeed, filled and missing teeth are indicators of having once experienced caries. However, with the ageing process, tooth loss could also be associated generally with periodontal disease. Nonetheless, the DMFT index remains the basis for caries measurement and has important epidemiological significance [37–40]. Fourth, we investigated the association between regional context and dental caries experience according to gender and age groups. Because we performed multiple subgroup analyses, the probability of a false positive finding should be considered . Finally, our results may have been affected be residual confounding by other behavioural and regional characteristics related to caries experience, such as sugar-related dietary habits and oral hygienic status, including the use of fluoride toothpastes and mouth rinses. Water fluoridation is an important issue affecting caries-related community factors, but Korean National Oral Health Survey (KNOHS) data do not include such information; however, the coverage rate is very low. Additionally, we did not obtain health insurance information because the Korean government’s national health insurance system covers almost all Koreans. Although some preventative and aesthetic dental treatments are not covered, basic treatment for dental caries, such as dental filling, is covered by national health insurance. Overall, further studies are needed to address the limitations of the present study.