RESUMO
Objective: To assess the relationship between asthma, malocclusion and mouth breathing. Material and Methods: This investigation was a cross-sectional study of 228 children between 6 and 12 years of age, of whom 112 were asthmatic and 116 were not, performed in two Primary Health Units of Porto Alegre, Brazil. The assessment consisted of a mouth exam performed by two calibrated dentists, an interview with parents/caregivers and medical chart data. Mouth breathing was determined through oral-facial changes related to Mouth Breathing Syndrome. Occlusion was assessed according to Angle's Classification for permanent or mixed teeth and regarding primary teeth were based on the canine relationships. The data were assessed by the Chi-square test and Poisson regression, with robust variation, at a p<0.05 significant level. Results: Asthma [PR = 2.12 (95% CI: 1.46-3.08), p<0.001] and the use of pacifiers [PR = 1.98 (95% CI: 1.27-3.07), p<0.001] were associated with mouth breathing, in the final multivariate model. Age [PR = 1.02 (95% CI: 1.00-1.03), p=0.039] and thumb sucking [PR = 1.08 (95% CI: 1.03-1.13), p=0.001] were associated with malocclusion in the final multivariate model, while there was no relationship between asthma and malocclusion (PR = 1.00; 95% CI: 0.94-1.07). Conclusion: This study provides evidence of the relationship between asthma and mouth breathing in children, demonstrating that knowledge regarding the oral health of populations with chronic diseases is fundamental for developing health programmes suitable to their needs and risks.