Crowding of the dental arches: a longitudinal study of the age period between 6 and 12 years

Abstract

Two groups of cases were analysed longitudinally: (1) A group with normal occlusion at 12 years (N-group) n = 30 and (2) a group with crowding at 12 years (Cr-group) n = 41. The latter was characterized by lack of space of at least 3.5 mm in one or both of the dental arches. Plaster models and lateral skull radiographs of the same children, had also been collected at the ages of 6 and 9 years. It was found that crowding developed during the observation period and that the inter-group differences were insignificant at the age of 6 years. The number of second deciduous molars lost early was markedly higher in the Cr-group. For the upper arch, a significant negative correlation was found between the dimension s-n at 6 and the individual development of crowding, while a positive correlation was found with the change in width between temporary and permanent incisors. For the lower arch, negative correlations were found between the development of crowding and lower facial length. The children of the Cr-group, when compared to the N-group, were characterized by significantly lower mean values for mandibular length.