Trends in self-rated poor oral health among all age populations in Korea from 2007 to 2015: monitoring expansion of dental insurance

Objectives:This study explored trends in self-rated poor oral health (SRPOH) from 2007 to 2015 among all age groups to monitor changes after the expansion of dental insurance.Methods:Repeated cross-sectional data from 2007 to 2015 Korea National Health and Nutrition Examination Surveys were collected and analysed. The respondents (n = 20,199) were categorised into four age groups: 0-19, 20-44, 45-64, and >= 65 years. The outcome variable was SRPOH, with independent variables being socioeconomic factors, sex, household income, and education. The age-sex standardised prevalence rate was calculated to determine trends, and complex samples logistic regression analysis was performed to confirm the factors affecting SRPOH.Results:Self-rated poor oral health prevalence decreased significantly from 2007 to 2009 (25%) to 2013 to 2015 (14%) in the age groups of 0-19 and 20-44 years (P < 0.05), whereas the SRPOH prevalence in the age groups of 45-64 and >= 65 years did not undergo any significant changes. Although the prevalence decreased by 6% among older adults, over 40% older women still experienced SRPOH. A sex gap increased with age but did not change over time. SRPOH was strongly associated with sex, income, and education across all age groups; the association did not notably change from 2007 to 2015.Conclusions:Self-rated poor oral health improved among younger people in Korea. The gender gap in the prevalence increased with age and persisted over time. However, income was the strongest determinant of SRPOH among all age groups, regardless of dental insurance expansion. Further studies should aim to draw causal inferences to explore the policy impact of dental insurance benefits.