Studies on gingivitis in children and adolescents are scarce and the results are inconclusive. The aim of this study was to assess the prevalence and extension of gingivitis and associated factors in Brazilian schoolchildren.

Cross‐sectional data from 1,211 schoolchildren 8 to 12 years old from Southern Brazil in 20 public and private schools were analyzed. Socioeconomic, demographic, and oral hygiene habits were assessed by questionnaires answered by parents and children. Buccal examination assessed presence of plaque, crowding, and gingivitis. Data were analyzed using Poisson regression [prevalence ratio (PR); 95% confidence interval (CI)].

Prevalence of visible plaque was 89.7% (95% CI 88.0‐91.3) and gingival bleeding on probing was 78.4% (95% CI 76.1‐81.0). The mean and median numbers of sites with gingival bleeding were 3.10 and 2 (SD ± 3.22), respectively. In multivariate adjusted analysis, the presence of a greater number of sites with plaque was significantly associated with gingivitis (PR 1.26; 95% CI 1.07‐1.47) and its extension (PR 1.96; 95% CI 1.53‐2.51). Lighter‐skinned black children had a lower probability of having severe gingivitis (PR 0.69; 95% CI 0.48‐0.98) compared with white children. This association was observed after adjusting for other variables.

Gingivitis was associated with higher number of sites with plaque and with skin color, reflecting the influence of biological and demographic factors on this oral condition.