1 Department of Oral Radiology, School of Dentistry, Federal University of Bahia, Salvador, Brazil

2 Department of Orthodontics, Dental School, Federal University of Bahia, Salvador, Brazil


Background: Rapid maxillary expansion (RME) is an important method for correcting maxillary transverse deficiency.
Objectives: The aim of this study was to assess the variations of the palatal plane in the anteroposterior and vertical directions after RME observed under cone-beam computed tomography.
Methods: The images using the cone-beam computed tomography were obtained from the skull of 15 patients (10 males, 5 females) with ages from 7 to 14 years, at the specialization course in orthodontics of the School of Dentistry at UFBA before (T0) and after (T1) RME using the Haas-type expander. The sagittal slices were obtained with Dolphin imaging program, premium version 11.0, in order to visualize the most anterior and posterior extremities of the maxillary bone and the following points: Sella (S), nasion (N), anterior nasal spine (ANS) and posterior nasal spine (PNS). The distances between points S and PNS (L1) and between N and ANS (L2) and the angles formed by the intersection of line SN with the palatal plane (angle 1) and line SN with line N-ANS (angle 2) were measured.
Results: The values obtained were statistically analyzed using Students t-test. At the time intervals assessed, no statistically significant difference was found in the linear measurements L1 and L2 (P = 0.296 and P = 0.674, respectively). No statistical significance was found when assessing angles 1 and 2 (P = 0.673 and P = 0.589, respectively).
Conclusions: RME using the Haas-type expander does not cause any alterations in the vertical or sagittal position of the maxilla.