METHODS: Publicly available data related to oral health measures, country income status, and membership in the Organization of Islamic countries were used. Five oral health-related measures were examined: caries experience (decayed, missing, and filled teeth (DMFT)), percentage of the population with no periodontal disease, and disability-adjusted life years (DALY) attributed to oral conditions, and mouth and oropharynx cancer. One-way analysis of variance (ANOVA) and Kruskal-Wallis tests were used to compare the oral health parameters by country income status and simple linear regression was used to compare the parameters between the non-member countries (n-MC) and member countries (MC). For the significant parameters, adjusted coefficients were obtained using multiple linear regression.

RESULTS: From 170 countries included, 53 (31%) were MC and 117 (69%) were n-MC. Analysis showed that the mean DMFT in adults aged 35-44 years was significantly higher in the n-MC compared to MC after adjusting for country income status (p<0.05) but the latter was the stronger explanatory predictor of the outcome. The strength of the effect of country membership classification (standardized coefficient β: DMFT35-44-year-old = -0.16) was smaller than country income status (β = -0.60) in the multiple regression.