Evaluation of the Effect of Different Rapid Maxillary Expansion Appliances on Airway by Acoustic Rhinometry

The patients were treated with KBME, Hyrax and MIDME maxillary expansion appliances, respectively. All expansion appliances containing a Hyrax expansion screw positioned parallel to the second premolars and were used to correct the posterior crossbite. In the MIDME group, two mini-screws with a diameter of 1.6 mm and a length of 10 mm are located on the right and left sides between the roots of the 2nd premolar and 1st molar teeth with 60-70° angle. KBME and Hyrax expansion appliances were cemented with glass ionomer cement and MIDME was cemented with using the light-cured composite. Same protocol was applied to all patients during RME treatment. Expansion screws in all groups were activated by two turns a day.