Introduction Dental pain significantly impacts child's life. This study explores the determinants of lifetime dental pain (LDP) among children.

Methods Data from a follow-up of two birth cohorts in Brazil was used: Ribeirão Preto (RP) with one of highest Human Development Index (HDI) in the country and Sao Luiz (SL) one of the lowest. Follow-up data (1/3 of original cohort) was collected in 2004/5 when children from RP were 10/11 years old (n=790), and children from SL were 7/8 years old (n=673). Prevalence Ratios (PR) were calculated and multivariable analyzes was performed hierarchical modelling. Covariates were mother education, age, marital status, sex, skin colour, number of siblings and number of household members, mother's perception of child oral health, dental visit, and private dental insurance.

Results LDP prevalence in RP was 32.7%, while in SL was 56.4%. Common variables in the final model for the two cities were sex, mother's education, mother's perception of child oral health. For RP private health insurance (PR 0.67; 95% CI 0.46 to 0.95) and marital status (PR 1.10; 95% CI 0.87 to 1.40) were also included in the model. For SL visiting dentist in the past 2 years was positively associated with LDP (PR: 1.22 95% CI 1.07 to 1.39) as well as the number of household members with children in families with more then five members showing PR 1.36 (95% CI 1.03 to 1.79).

Conclusion The prevalence of LDP in both cohorts was relatively high and specially associated with family structure and socioeconomic position.