The goal of our study is to expand the maxillary arch sufficiently with 3 different expansion methods in the cases with posterior cross-bite in mixed dentition and to evaluate the results within a short period of time, The research has been made on 10 patients, mean ages 8 months and 8 years from whom occlusal x-rays, antero-posterior x-rays and orthodontic casts were obtained. The ‘Hyrax’ screw appliance for rapid maxillary expansion, removable ‘Jackscrew’ appliance for semi-rapid maxillary expansion and 2 different quadhelix appliance for slow maxillary expansion have been used. The dental and skeletal effects of these appliance were evaluated. Satisfactory expansion were obtained in all the patients, while different skeletal results were observed.

Keywords: Quadhelix, MOD 3D Lingual sistem, Rapid Maxilllary Expansion, Semi-rapid Maxillary Expansion, Slow Maxillary Expansion, Removable Appliance, Quad-helix, MOD 3D Lingual System