1. IntroductionOver recent decades, low- and middle-income countries (LMICs) have undergone a nutrition transition from breastfeeding to bottle-feeding and from traditional diets to ultra-processed and sugary foods and beverages. These dietary shifts have contributed to dramatic increases in the prevalence of diet-related chronic diseases including dental caries, obesity, type 2 diabetes, and cardiovascular disease [1,2].Dental caries is the most prevalent chronic disease of childhood, affecting 60–90% of children worldwide [2]. Early childhood caries (ECC), defined as tooth decay in children under six years of age, can cause severe dental infections, mouth pain, and interfere with a child’s nutrition, growth, development, and overall health and quality of life [3,4]. ECC is a multifactorial disease, and the interplay of risk and protective factors has been illustrated through different models. The Keyes Caries Triad delineates the interaction between dietary sugar, cariogenic oral biofilm, and underlying child health factors contributing to caries [5]. The Caries Balance Model depicts the opposition of caries-causing factors (e.g., dietary sugars) and caries-preventive factors (e.g., fluoride and saliva) [6].Many studies have shown that children’s oral health outcomes are strongly affected by social and structural factors. A conceptual model of determinants of oral health included social factors at family and community levels (e.g., parent education, economic factors, cultural practices, access to foods/beverages and dental care) that can contribute to or prevent caries [7]. Recent models of the Social Determinants of Oral Health also incorporate commercial determinants of oral health, including the global marketing of sugary drinks and ultra-processed foods that drive the nutrition transition, as well as political, economic and research priorities, and racism, which can adversely affect access to services and health outcomes for racial and ethnic minority populations [8,9,10]. In LMICs and low-income populations in high-income countries, cross-sectional studies have demonstrated that prolonged bottle-feeding and frequent consumption of sugary drinks and snacks contribute to increased risk of ECC [11]. However, systematic reviews, and cross-sectional and longitudinal studies of social determinants of health (e.g., maternal education and family income) have shown contrasting associations with ECC—some positive, some negative, and some “U-shaped” with higher caries rates in both low- and high-income populations [12,13,14,15,16,17].Multiple cross-sectional studies have indicated that individuals with higher socioeconomic status (SES) tend to have healthier practices and better health outcomes than those with lower SES [18,19,20]. Specifically, much evidence points to education as playing a key role, as education can improve one’s knowledge, habits, skills, and resources, which in turn improve one’s health behaviors and lifestyle choices, leading to overall healthier outcomes [20,21]. Therefore, education level is often considered a good proxy measure of SES in oral health studies and maybe a focal point for intervention.Ecuador is a middle-income Latin American country that has experienced a nutrition transition with persistently high rates of malnutrition and increasing rates of obesity and ECC [22,23,24,25,26]. Ecuador currently has free and compulsory public education from age 6 to 14, including primary school for grades 1 through 6 [27], and free public healthcare, including dental care; however, low-income, rural and indigenous populations have experienced barriers in access to education and healthcare. The most recent oral health data from the 2010 national health survey found that 80% of 6-year-old children had dental caries [24]. There are wide economic and health disparities, especially in rural and indigenous populations who have higher rates of poverty and stunting malnutrition, as well as high rates of dental caries [23,25,28,29,30,31,32,33,34,35]. A study in the Amazonian region of Ecuador found that 92% of indigenous and 95% of non-indigenous 6-year-old children had dental caries, with a mean of 6.4 and 8.4 decayed teeth, respectively [30].Global health organizations have advocated policies and community-based interventions to promote oral health, especially for underserved and indigenous populations [36,37,38,39]. However, the social determinants of ECC in Ecuador, particularly for rural and indigenous communities, remain understudied, and very few studies have specifically examined the relationship between maternal education and child nutrition or oral health-related behaviors and outcomes [28,29,30,31,32,33,34,35]. This study aimed to explore whether mothers in a rural, indigenous population in Ecuador who had a greater number of years of education might also have children with better oral health outcomes. 4. Discussion

This cross-sectional study of a convenience sample of children aged 6 months through 6 years and their mothers/caregivers from a rural indigenous Ecuadorian community explored the associations between maternal education and maternal-child oral health practices and child oral health outcomes. Specifically, we identified 2 pathways: the education-practice relationship to understand the relationship between years of maternal education and oral health practices, and the education-outcome relationship to understand the relationship between years of maternal education and child oral health outcomes (primary study outcome).

In the education-practice relationship, we found that a one-unit increment in the years of maternal education was significantly associated with some healthy practices as well as many unhealthy practices, but not significantly associated with the mother’s knowledge of the causes of childhood caries, mother or child dental visits, prenatal care, child vaccination, and child nutritional status. In the education-outcome relationship, a one-unit increase in the years of maternal education was shown to significantly decrease the expected number of a child’s total dmft and the expected number of a child’s untreated decayed teeth.

This study supports the findings of other systematic reviews, meta-analyses, and cross-sectional studies showing high rates of ECC in Ecuador, including in indigenous populations [26,30,52,53]. Our results are consistent with findings from other cross-sectional studies in LMICs regarding the widespread practice of feeding young children sugary beverages and snacks [54,55], limited parental knowledge about the contribution of the baby bottle and sugary beverages to ECC [56], and the need to help children with tooth brushing until age 8 [57]. Our study also supports other global studies showing limited access to dental care, especially for low-income, rural, and indigenous populations, and widespread suffering of children and adults from untreated dental caries [2,3,8].This study contributes to the global debate on the association between maternal education and child oral health, for which systematic reviews, cross-sectional and longitudinal studies have shown disparate findings [12,13,14,15,16]. Our study suggests that years of maternal education was not predictive of oral health knowledge, but it did predict some healthier and unhealthier practices, which may tip the balance toward either greater risk or lower risk for ECC depending on the local social and commercial determinants of health. We hypothesize that, in this population, maternal education may contribute to greater likelihood of employment outside of the home, which may lead to reliance on bottle-feeding, less time to brush their children’s teeth, added income, and desire to give their children treats that are accessible at their local store – including milk, soda, and junk food. A longitudinal study in Australia has shown that children of full-time employed mothers were more likely to consume high-sugar drinks compared to children of part-time employed mothers [58]. A recent global study found that women’s economic empowerment was associated with many benefits, but it was also associated with greater risk for ECC [59].Our findings also suggest that academic schooling alone is unlikely to improve oral health knowledge and oral health and nutrition practices and outcomes. Most schools do not include effective instruction on healthy diets, toothbrushing, and dental care [60]. To the contrary, children attending school are frequently exposed to many risks for poor nutrition and oral health, such as stores adjacent to the schools selling sugary drinks and junk food, mobile vendors coming to school sites to sell junk food, and daily school-sponsored snacks and beverages with high sugar content [61]. While most child oral health interventions rely on providing maternal education on oral health and dental treatment for children, it appears that the role of maternal education in determining child oral health outcomes may not be as strong as other socio-structural and commercial factors. Our study suggests a more complex set of social determinants of oral health, and a need for more intensive interventions at child, family, and community levels to address the socio-structural and commercial drivers of disease including expanded nutrition and oral health education, access to dental care for all children and adults, and implementing national and local policies to support basic income, nutrition and education, and limits on the adverse commercial determinants of oral health.In 2014, the Pan American Health Organization and all Latin American countries signed an agreement to support school nutrition programs and prohibit non-nutritious snacks and beverages from schools, with the aim of preventing childhood obesity [62]. From 2014–2015, Ecuador implemented several important nutrition programs: (1) “Traffic-light” labeling of pre-packaged processed foods and beverages, indicating whether the product has high (red), moderate (yellow) or low (green) levels of sugar, fat, and salt; (2) Regulations on school food vendors prohibiting sale of products high in sugar, salt, or fat and requiring sale of fruits and vegetables, and provision of free, safe water; and (3) An added tax on processed sugary drinks of USD 0.18 per 100 g of sugar. Evaluations of these regulations found moderate levels of compliance and improvement in nutrition awareness and emphasized the need for ‘scaling up’, monitoring and enforcement of the regulations, and increased funding for health promotion [56,57]. Another evaluation found that families continued to call for greater access to healthy foods and limits on marketing of unhealthy products to their children, while food industry representatives and some government officials continued to advocate for industry ‘rights’ to market their products without regulation, and academics called for further research [59].While Ecuador has focused on policies to promote nutrition, there is an unmet need for equal focus on oral health. The World Health Organization, FDI World Dental Federation, and the Lancet Commission on Oral Health have advocated a global life-course approach to improving oral health, including oral health education and dental clinical services incorporated into primary health care as part of Universal Health Care from prenatal care through well-child/immunization programs and adult healthcare, utilizing a broader primary health care network including nurses and community health workers, and incorporating toothbrushing programs into childcare and schools [8,60,61,62,63,64,65,66,67,68]. Experts also emphasize that engaging the local community in the design and implementation of services, as well as dismantling structural racism, are critical to ensure accessibility, acceptability, and effectiveness [63].

This study contributes to the literature by elucidating the relationships between maternal education and maternal-child oral health practices and oral health outcomes in this LMIC population. This study has many limitations: The cross-sectional nature of the study does not allow for temporality to be established, and therefore we cannot prove causality. The convenience sampling method may limit the generalizability of the findings beyond this specific population, but also serves as a strength for the inclusion of diverse communities. Survey responses may be susceptible to recall bias and social desirability bias. There also may have been clustering at the family and community level for which this exploratory analysis did not account. While we conducted an exploratory analysis of the relation between years of maternal education and our mediator (oral health practices) and our primary outcome independently, it may be valuable to conduct a mediation analysis in the future. This analysis focused on only maternal education as a social determinant of oral health; but since we found that the role of maternal education was not as strong as prior studies have suggested, it may be worthwhile to explore the impact of other social, economic, environmental, and commercial factors on maternal-child oral health practices and outcomes. Finally, this study assessed community nutrition and oral health prior to the implementation of national policy interventions to improve child and adult nutrition. Future research should follow-up with these communities to assess the impact of the policies on nutrition and oral health and identify additional interventions that may be impactful.