[The relationship between oral habits and malocclusion in preschool children].

OBJECTIVE To evaluate the way oral habits and speech problems affect dental occlusion in preschool children. METHODS A random sample of 2,139 boys and girls aged 3-5 years old was evaluated. The children were enrolled in private and state institutions in the city of Bauru, São Paulo State, Brazil. The cross-sectional study was developed in two steps: occlusion assessment, and a questionnaire about their social and economic status. The occlusal anatomical-functional characteristics assessment was done according to Angle classification. Additionally, overjet, overbite, crowding, anterior open bite, posterior crossbite, and anterior crossbite were evaluated. A sub-sample of 618 children filled out the questionnaire. The prevalence of malocclusion and some variables of exposure were tested by bivariate analysis. RESULTS The prevalence of malocclusion was 51.3% for boys and 56.9% for girls. There was no difference related to gender. In regard to age, there was a higher prevalence of malocclusion in the 3 year-old group, which decreased significantly with age (p<0.05). CONCLUSIONS Among the environmental factors evaluated, the habit of sucking a pacifier was the most important in the association with malocclusion (OR=5.46) followed by the habit of sucking fingers (OR=1.54). Speech problems did not show any influence in malocclusion occurrence.