Dimensional changes in the dental arches of orthodontically treated cases.

Integrated data from lateral cephalometric radiographs and study models of fifty-three patients were studied to assess the interactions between dimensional changes occurring during orthodontic treatment and the postretention stability of these changes. A new technique was developed to study distal movement of canines. Distal movement of canines did not ensure a stable increase in intercanine width. There was no significant relationship between mesiodistal position of the first molars and changes in intermolar width. Eruption of the first molar in the postretention period was associated with greater stability in overbite. There was no great degree of correlation between depth of the curve of Spee and inclination of the occlusal plane or between changes in arch length and changes in inclinations of the incisors.