Education-related inequalities in oral health among older adults: Comparing Singapore and Japan

Objectives: Oral health inequalities exist worldwide, and cross-country comparisons can provide valuable insights into country-level characteristics contributing to such inequalities. However, comparative studies in Asian countries are limited. This study examined the magnitude of education-related oral health inequalities in older adults in Singapore and Japan. Methods: Longitudinal data for older adults, aged & GE;65 years, from the Panel on Health and Ageing of Singaporean Elderly (PHASE; 2009, 2011-2012, and 2015) and Japan Gerontological Evaluation Study (JAGES; 2010, 2013, and 2016) were used. Dependent variables were being edentate and having a minimal functional dentition (MFD; i.e. >= 20 teeth). The absolute and relative inequalities were calculated using the slope index of inequality (SII) and relative index of inequality (RII) for educational level [low (< 6 years); middle (6-12 years); high (> 12 years)] in each country. Results: A total of 1032 PHASE participants and 35 717 JAGES participants were included. At baseline among PHASE participants, 35.9% were edentate and 24.4% had MFD, while among JAGES participants, 8.5% were edentate and 42.4% had MFD. The prevalence of low, middle and high educational levels for PHASE was 76.5%, 18.0% and 5.5%, and for JAGES were 0.9%, 78.1% and 19.7%, respectively. Older adults in Japan had lower education-related inequalities for being edentate [for both SII (-0.53, 95% CI = -0.55 to -0.50) and RII (0.40, 95% CI = 0.33-0.48)] and for not having MFD for both SII (-0.24, 95% CI = -0.27 to -0.20) and RII (0.83, 95% CI = 0.79-0.87) compared to Singapore. Conclusions: Education-related inequalities for being edentate and not having MFD were higher among older adults in Singapore compared to Japan.