TREND OF INCOME-RELATED INEQUALITY OF UNTREATED DENTAL CARIES IN SOUTH KOREA

Abstract

Aims: The rate of Korean National Health Insurance (KNHI) coverage for dental health is around 15% (OECD, 2016), and the low coverage is a major barrier affecting access to dental care. The aim of the present study was therefore to examine trends in income-related inequality in untreated dental caries in South Korea.

Methods: Cross-sectional data were obtained from the Fourth (2007-2009) and Sixth (2013-2015) Korea National Health &Nutrition Examination Survey. A nationally representative sample of 21,197 from KNHANES IV and 17,543 from KNHANES VI, over the age of 5 years who participated in the health interview and dental examination were used. Dental examination data for deciduous cares in 5- to 10- year-olds and permanent caries in children (6-11 years), adolescent (12-18 years), adults (19-64 years), the elderly (65 years and older) by trained dentist-examiners were analyzed. Household income was monthly household equivalent income, which is obtained from household income / (the 0.5 power of the number of household members). Trends were studied using indices for both the absolute and relative size of socioeconomic inequalities in dental caries. Age standardized rates, Slope Index of Inequality (SII) and Relative index of inequality (RII) were calculated by SAS statistical software.

Results: Age-standardized prevalence of untreated dental caries decreased in all age groups between 2007-2009 and 2013-2015, while deciduous caries among child aged 5-10 did not decrease. Income related inequalities decreased in permanent teeth, but not in deciduous teeth, among Korean children. The absolute and relative level of socioeconomic inequality in untreated dental caries remained virtually unchanged in adults. Meanwhile, relative level of socio- economic differences in dental caries have increased over time in adolescent and the elderly group.

Conclusions: In the study population, since oral health inequalities still exist at all ages, policies and interventions to reduce socioeconomic inequality in dental caries especially among adolescents and adults, need to be developed in South Korea. It is necessary to expand the dental care coverage of national health insurance and to form a social discourse on oral health inequality in South Korea.