RESUMO
BACKGROUND: The literature is controversial with regard to the association between longer breastfeeding duration and lower prevalence of anterior open bite. Pacifier use may be involved in this controversy. Thus, the objective of the study was to assess the influence of pacifier use and its duration on the association between longer breastfeeding duration and lower prevalence of anterior open bite in children with primary dentition. METHODS: This was a cross-sectional study nested in a cohort study involving 153 infants recruited at a maternity hospital in the municipality of Porto Alegre, southern Brazil. The study outcome (anterior open bite) was assessed when the children were between 3 and 5 years old. Data on breastfeeding and pacifier use were collected at 7, 30, 60, 120, and 180 days of life and on the date of the evaluation here described. Poisson regression with robust variance was used to analyze the association between the prevalence of anterior open bite and breastfeeding duration, expressed in months. RESULTS: The univariate analysis showed a protective effect of breastfeeding against anterior open bite (prevalence ratio [PR] 0.96; 95% confidence interval [95%CI] 0.95-0.98). This effect remained significant after adjustment for pacifier use at any time between birth and the date of dental assessment (PR0.98; 95%CI; 0.96-0.99), i.e., there was a reduction of 2% in the prevalence of anterior open bite for each month of breastfeeding. However, this effect lost significance when pacifier use duration was included in the multivariate analysis (PR1.00; 95%CI; 0.99-1.01). CONCLUSIONS: Pacifier use duration influences the association between longer breastfeeding duration and lower prevalence of anterior open bite. It is likely that prolonged pacifier use reduces the magnitude of this association.