Three-Dimensional Displacement of Partial Craniofacial Bones Following Rapid Maxillary Expansion in Young Patients with Angle Class III Malocclusions

Objective: The aim of this study was to analyze the displacement in 3D direction of some craniofacial bones with the rapid maxillary expansion in Angle class III malocclusion. Method: Thirteen Angle class III patients (mean age: 12.4 ± 1.7 years; 7 males, 6 females) using rapid maxillary expansion as part of their orthodontic treatment were selected and computed tomography scans were taken before and after expansion. The 3D models were reconstructed using the Mimics software and the maxillary, zygomata, nasal bones were separated. With 3D models correction and registration, the displacements in the 3D directions of partial craniofacial bones were measured. Quantitative variables were analyzed by using SPSS19.0 and a t value less than 0.05 was considered statistically significant. Results: Measurement results showed that rapid maxillary expansion produced significant displacement in both sides of the maxillary, zygomata, and nasal bones. In the width of the midline palatine suture, the anterior nasal spine point was expanded a mean 4.18 mm (range 2.42 mm–5.68 mm, Pleft = 0.007, Pright = 0.014) and the posterior nasal spine point was expanded a mean 2.14 mm (range 1.96 mm–2.43 mm, Pleft 

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