The change in lower arch crowding 3-4 years after second permanent mol
ar eruption was examined in 85 subjects, in relation to the angulation
and change in angulation of molars and incisors relative to the mandi
bular plane using correlation and multiple regression analyses. Crowdi
ng increased significantly during the observation periods. Changes in
molar and incisor angulation in both mesial and distal directions were
observed. The increase in crowding was not related to molar or inciso
r angulation at 12 years, Some association between increase in crowdin
g, reduction in arch depth and retroclination of incisors was found.