Does Nationwide Scaling Insurance Policy Reduce Inequalities In Scaling Usage?

Objectives: The purpose of this study was to determine the impact of the 2013 nationwide dental scaling insurance policy on inequalities in dental scaling usage in South Korea.
Methods: A nationally representative sample of 1,517,097 people, over the age of 20, who had completed information on dental scaling and household income, were included from the 2010-2016 Community Health Survey (CHS). Respondents who answered they had not received dental scaling in the past year were defined as dental scaling non-users. Absolute and relative inequalities in dental scaling usage were measured with the excess prevalence and relative prevalence ratio of dental scaling non-users. Excess prevalence and relative prevalence ratio of dental scaling non-users were calculated in the pre-policy (2010-2012 years) and post-policy (2014-2016 years) periods, by monthly household income levels ( <1 million, 1 million≤ <3 million, 3 million≤ <5 million, ≥ 5 million KRW).
Results: The prevalence of dental scaling non-users has declined from 580 to 487/1000 (16%) in household income ≥ 5 million KRW group, and from 863 to 788/1000 (8.7%) in household income < 1 million KRW group. Despite these improvements, the adjusted excess prevalence for household income < 1 million KRW group compared with household income ≥ 5 million KRW group was increased from 126 to 161/1000, and adjusted prevalence ratio was increased from 1.20 (95% CI: 1.19-1.22) to 1.31 (95% CI: 1.29-1.31).
Conclusions: The nationwide dental scaling insurance policy inadvertently increased the socioeconomic inequalities in dental scaling usage. Downstream and agentic interventions targeted to change individual behaviors alone may have limits to attenuate, instead of widening the social gradients in oral health inequalities.