Income inequality and traumatic dental injuries in 12-year old children: a multi-level analysis

Background/Aim: Contextual socioeconomic factors have been associated with traumatic dental injuries (TDIs). However, evidence concerning the role of income inequality on TDIs in children is scarce.The aim of this study was to investigate the association between contextual income inequality over a ten-year period and TDIs in Brazilian children. Subjects and methods: The study population comprised a representative sample of 5027 children aged 12 years who participated in the Brazilian oral health survey in 2010. City-level Gini Index was used to measure contextual income inequality in the years 2000 and 2010, as well as the variation in income inequality between 2000 and 2010. Covariates were gender, ethnicity, family income, number of people per room and incisal overjet. Clinical examinations were used to assess TDIs. Multivariable multilevel ordered multinomial logistic regression was used to estimate cumulative Odds Ratio (OR) and 95% confidence intervals between income inequality and TDIs. Results: The prevalence of children who had one tooth with TDI and two or more teeth with TDIs was 15.2% and 6.4%, respectively. The maxillary central and left lateral incisors were the teeth most affected by TDIs. Gini coefficient reduction between the years 2000 and 2010 decreased the odds of TDIs even after adjustment for demographic and socioeconomic characteristics, and incisal overjet. The likelihood of more TDIs decreased 21% for each 0.05 unit decrease in the Gini coefficient between the years 2000 and 2010. Boys, brown skin colour, overcrowding and incisal overjet greater than 5 mm remained statistically associated with TDIs in the final model. Conclusions: The decrease in income inequality over a ten-year period was inversely associated with TDIs among Brazilian children aged 12 years