The aim of this study was to determine the sagittal, transverse, and vertical effects of a
Nitanium maxillary expansion appliance on dentofacial structures in patients with bilateral posterior
cross bites in the permanent dentition. For this purpose, and without distinguishing the skeletal classification, a total of 16 patients (4 boys and 12 girls) with a mean age of 13.8 years and a bilateral posterior
crossbite in the permanent dentition were chosen. Lateral and frontal cephalometric radiographs, maxillary and mandibular plaster models and periapical radiographs were obtained from each patient at pretreatment (T1), post-treatment (T2), and at the end of the retention period (T3) time points. The measurements that were obtained from the lateral and frontal cephalometric radiographs and maxillary and mandibular plaster models were evaluated by a Wilcoxon paired 2-sample test. This test compares 3 pairs of time points, the pretreatment (T1) and posttreatment (T2), the pretreatment (T1) and post retention (T3), and the post-treatment (T2) and post retention (T3). Periapical radiographs were used to demonstrate changes in the midpalatal
suture. Skeletal expansion occurred simultaneously with dentoalveolar expansion in the transverse plane with the
Nitanium maxillary expansion appliance. The upper incisors were extruded and retroclined. Also, the extrusion of the upper first molars caused the mandible to rotate backward and downward. This resulted in an increased
vertical dimension of the lower face. It was clinically observed that the posterior
cross-bite and mesiopalatal rotation of the upper first molars were improved and that the
crowns of these teeth were moved slightly to the distal side.