BackgroundDigit sucking, tongue thrust swallowing, and mouth breathing are potential risk factors for development of malocclusion. The purpose of this study was to verify the prevalence of different occlusal traits among 5–7-year-old children and assess their relationship with oral habits.Material/MethodsThe study included 503 pre-school children (260 boys and 243 girls) with a mean age of 5.95 years. Different occlusal traits were verified by intraoral examination. Oral habits were diagnosed using data gathered from clinical examination of occlusion and extra-oral assessment of the face, combined with a questionnaire for parents.ResultsThe study demonstrated that 71.4% of the children presented with 1 or more attributes of malocclusion and 16.9% had oral habits. The vertical and sagittal malrelation of incisors, as well as spacing, were the predominant features.This study showed that digit suckers have higher incidence of anterior open bite (P=0.013) and posterior crossbite (P=0.005). The infantile type of swallowing demonstrated strong association (P=0.001) with anterior open bite.ConclusionsNon-nutritive sucking habits and tongue thrust swallowing are significant risk factors for the development of anterior open bite and posterior crossbite in pre-school children.