Arch dimensional changes during and following fixed appliance therapy.

A retrospective investigation of the study casts of 23 subjects, treated by Fixed Appliances and the extraction of four premolars, using the Reflex Metrograph showed a general trend for a reduction in mean arch dimensions both during and following treatment. An exception was demonstrated in the intercanine width, which for both arches showed slight expansion during treatment, although this was lost post-treatment in the mandibular arch while it was maintained in some cases in the maxillary arch.