Introduction The anterior open bite is the malocclusion with major aesthetic and functional commitments, besides it has a more complex treatment. In order to prevent its occurrence, it's fundamental to know the risk factors.

Objective To estimate the prevalence of anterior open bite and to examine the effects of some variables such as behaviours and those related to familiar environment.

Methods A cross-sectional study was carried out in Salvador—BA, in 2005. A sample of 362 children aged between 2 and 5 years old was examined and their relatives were interviewed in their homes. The Self-Report Questionnaire (SQR-20) and CAGE scale (adaptated) were used to report psychiatric symptoms and alcoholism in the family. Descriptive analysis was proceeded. In order to verify the associations, OR, adjusted for the independent variables, was estimated through of non-conditional logistic regression.

Results The prevalence of anterior open bite was 19.19%. Results of the logistic analysis showed a positive association between non-nutritive sucking habits and anterior open bite in children (OR_ajust=7.44; 95% CI 3.30 to 16.74). There was no association between familiar dysfunction, referred to the presence of psychiatric symptoms and alcoholism in the family, and anterior open bite.

Conclusions Results suggest that there is, in the population studied, an association between sucking behaviour and the occurrence of anterior open bite in children. The knowledge of malocclusion in the primary dentition favours preventive actions to reduce the prevalence of malocclusion.