Cephalometric evaluation of Haas and Hyrax rapid maxillary appliances in the treatment of the skeletal maxillary transverse deficiency.

Abstract

Two different rapid palatal expansion appliances were compared, using lateral cephalograms, anterio-posterior cephalograms and diagnostic models. The Haas appliance was used on ten patients and the Hyrax appliance on another ten. A difference in the effect of the two appliances was found only for the increase in intermolar distance. This difference could be the result of the different appliance design.