Socioeconomic Inequality in Dental Caries Experience Expressed by the Significant Caries Index: Cross-Sectional Results From the RaNCD Cohort Study

INTRODUCTION: Socioeconomic inequality in dental caries among Iranian middle-aged adults remains largely unstudied. This study aimed to measure socioeconomic inequality in dental caries experience and to identify determinants of this inequality. MATERIALS AND METHODS: Data were obtained from the Ravansar Non-Communicable Diseases (RaNCD) Cohort Study. This cross-sectional analysis included 10,002 adults aged 35–65 years. Caries experience was dichotomised based on the decayed, missing and filled teeth (DMFT) of one-third of the population with the highest caries scores (i.e. significant caries index). Socioeconomic status (SES) was calculated using the principal component analysis. The concentration index (CI) was used to quantify the extent of socioeconomic inequality in dental caries experience. Decomposition analysis was conducted to quantify the contribution of each determinant to the observed inequality. RESULTS: The mean DMFT for all individuals was 16.1 (SD 9.1). The CI of having significant dental caries was –0.236 (95% CI: –0.0259, –0.213), indicating that having significant dental caries was more concentrated among low-SES individuals. SES (65.6%), age group (24.7%) and female gender (3.7%) were found to have the largest percentage of contributions to the observed inequality in dental caries. CONCLUSION: This study indicates pro-rich inequalities in dental caries experience among middle-aged adults in Iran. The findings highlight the importance of early prevention of dental caries experience before it happens. To mitigate inequalities in dental caries experience, policy interventions should focus on females, older age groups, and low-SES individuals.