Epidemiologic survey of functional conditions of the masticatory system in Belgian children aged 3-6 years.

In this epidemiologic survey 510 children aged 3-6 yr were investigated. Several occlusal and functional parameters were measured: the maximal interincisal distance, the frequency of lateral and frontal crossbite, open bite, the number of tooth contacts on lateral excursions of 3 mm, the wear facets, deviations in opening, pain in muscles and in the TM-joints, TMJ sounds, parafunctional habits. The interincisal distance varied between 25 and 55 mm. This distance increased with age. Only five children had a hypermobility of the mandible (opening more than 55 mm) and 11 a restricted opening movement (less than 30 mm). 7.2% showed a lateral crossbite on the right, and 8.9% on the left, side. The percentage of an open bite decreased with age from 66.7% in the 3-yr-olds to 20.0% in the 6-yr-olds. 33% of the children had only one contact on the working side. As reported by the parents 7.7% had regularly bruxism but 21.8% showed wear facets on the molars and 40.7% on the front teeth. Only in three girls were the TMJ painful to palpation. Dysfunction only occurred in 3.5% of the sample.