Supplementary Material for: Are Area-Level Socioeconomic Factors Associated with Dental Caries and Tooth Loss? A Systematic Review

Introduction: Area-level socioeconomic factors are within the social determinants of health, encompassing conditions in which people are born, grow, live, work, and age, which influence health beyond individual characteristics. This review examines the association between area-level socioeconomic factors and dental caries and tooth loss. The hypothesis is that individuals residing in more socioeconomically deprived areas experience higher odds of dental caries and tooth loss, independent of individual socioeconomic status.

Methods: A systematic search was conducted in PubMed, Scopus, Embase, and Web of Science. Studies reporting clinical or self-reported dental caries or tooth loss, and evaluating area-level socioeconomic deprivation or income (neighbourhood, municipality, or region) using multilevel models were included.

Results: Of 4,671 screened records, 44 studies (41 cross-sectional) published from 2006 to 2024 were included. The most common exposures were area socioeconomic deprivation indices (n=24), area average income (n=21), and the Human Development Index (HDI) (n=13). Quantitative synthesis was precluded by heterogeneity of aggregation levels, outcomes (tooth loss, caries experience, and untreated caries), and outcome measurement (dichotomous/continuous). Most studies adjusted for individual-level socioeconomic factors (82%). The hypothesised association was most consistent for tooth loss (e.g. functional dentition or edentulism, 6/6 studies), at a medium level of aggregation (13/15), and for the HDI (10/13). Studies using ordered categories frequently demonstrated clear socioeconomic gradients.

Conclusion: The findings support the hypothesis that residing in more affluent areas is associated with better oral health outcomes, specifically lower levels of tooth loss and, to a lesser extent, dental caries, after adjusting for individual-level socioeconomic factors.