Use of a modified butterfly expander to increase anterior arch length.

Abstract

intypical mixed dentition cases. The metal frame-work of this expander is shaped like a butterfly,with posterior arms welded to bands on the firstpermanent molars (Fig. 1).The Ragno screw has a posterior hinge,which makes the appliance fan out anteriorly,and two anterior hinges, which control torquingduring expansion. It is important to position the