Sex differences in the association between obesity and gingivitis among 12-year-old South Brazilian schoolchildren.

To assess the association between weight status and gingivitis in a representative sample of 12-year-old schoolchildren from South Brazil.An association between obesity and gingivitis in children and adolescents has been observed; however, the present evidence has major limitations.A cross-sectional study was conducted in Porto Alegre, South Brazil, from September 2009 to December 2010 and included a representative sample of 1528 12-year-old schoolchildren attending public and private schools. Data collection included the application of a questionnaire, recording of anthropometric measures (weight and height), and clinical examination (gingival bleeding index, recorded in four sites per tooth). The outcome of the study was the prevalence of gingivitis, defined as the proportion of schoolchildren presenting ≥52% of bleeding sites (based on the median). Weight status was categorized according to body mass index into normal, overweight, or obese. The association between predictor variables and gingivitis prevalence was assessed using Poisson regression models. Unadjusted and adjusted prevalence ratios (PR) and their 95% confidence intervals (95% CI) were estimated.Gingivitis prevalence was 48.7% (95% IC = 33.8-63.6) and, on average, schoolchildren presented 51.8% (95% IC = 46.2-57.5) of bleeding sites. Obese individuals had 13% higher prevalence for presenting gingivitis than did normal-weight ones (PR = 1.13, 95% CI = 1.09-1.18, P < .001). The stratified analysis showed that this association was sex-specific: Obese girls presented a greater chance of having gingivitis (adjusted PR = 1.21, 95% CI = 1.09-1.34, P < .001), but such association was not observed among boys (PR = 1.07, 95% CI = 0.95-1.20, P = .29).This study showed sex differences in the association between obesity and gingivitis among 12-year-old South Brazilian schoolchildren.