Social inequalities in adult oral health in 40 low- and middle-income countries.

OBJECTIVE: This study evaluated social inequalities in adult oral health across several low- and middle-income countries.

METHODS: We used data from 40 countries that participated in the World Health Surveys. Participants' socio-economic position was assessed using the wealth index. Oral health was assessed using two perceived measures, namely total tooth loss and whether they had any problems with their mouth and/or teeth during the last 12 months (perceived needs). Absolute and relative wealth inequalities in oral health were measured using the slope index of inequality (SII) and the relative index of inequality (RII), respectively, after adjusting for participants' sex, age and education.

RESULTS: There were wealth inequalities in total tooth loss and perceived needs in most countries. However, significant monotonic gradients were found in 21 countries for total tooth loss and in 18 countries for perceived needs. Two distinctive patterns of social inequality in oral health were found across countries using the RII and the SII. For total tooth loss, pro-rich inequality was found in 25 countries (significant RII/SII in eight countries) and pro-poor inequality was found in 15 (significant RII/SII in three countries). For perceived needs, pro-poor inequality was found in 26 countries (significant RII/SII in six countries) and pro-rich inequality was found in 14 (significant RII/SII in five countries).

CONCLUSIONS: The well-documented social gradient in adult oral health favouring the rich was not present in all low- and middle-income countries. Pro-poor inequalities in total tooth loss, and particularly in perceived dental-treatment needs, were observed in some countries.