Theoretical explanations and empirical evidence for the relationship between income inequality and population oral health

Background: Over 300 studies have examined the hypothesised negative impact of high income inequality on health outcomes. Oral health is integral to general health. Several studies have examined the association between income inequality and oral health outcomes. A gap exists in the understanding of the theoretical basis for the income inequality and oral health relationship. The literature on income inequality and oral health at the sub-national level is limited to the USA, Japan, and Brazil. Australian evidence on the association between income inequality and general health outcomes is limited and inconclusive, and there is none for oral health. To address these gaps, this thesis by publication answered the following two research questions: Research Question (I): Which socio-epidemiologic theories can be used to explain the linkages between social inequalities and population oral health? Research Question (II): Is area-level income inequality inversely associated with population oral health in the Australian context? Methods: A scoping review identified different types of socio-epidemiologic theories used in the global literature on area-level social inequality and population oral health and analysed their extent of application. A population-based multilevel study used the data on oral health of 5,169 Australian dentate adults nested in 435 Local Government Areas (LGAs) from the 2013 National Dental Telephone Interview Survey (NDTIS-2013) to answer research question (II). Associations were tested between tertiles of LGA-level income inequality and oral health outcomes of inadequate dentition (presence of