Three-Dimensional Voxed-based Maxillary Superimposition for Everyday Practice

Superimposition of cephalograms has many uses in orthodontics, including growth evaluation and outcome assessments, but cephalograms are distorted and show incomplete two-dimensional data. Cone Beam Computed Tomography (CBCT) provides a three-dimensional undistorted and more complete analysis of our patients. Superimposition of 2 CBCT's is possible by using landmarks, surfaces, or density information (voxel-based). Voxelbased superimposition is automated and uses the most image content, providing the most accurate result. Until recently such superimposition was extremely laborious, but a user-friendly voxel-based superimposition has recently been introduced . Aim : to evaluate the accuracy and reliability of different methods of regional maxillary voxel -based superimposition. Methods: This is a retrospective study using existing scans of SO orthodontic patients. The sample will include 25 females and 25 males with a mean age of 12. Each patient had a pre-treatment (Tl) and a post-treatment (T2) scans taken within 24 months. The volumes will be superimposed using voxel-based methods from Dolph in Imaging Systems and different areas of registration will be tested and compared to each other and to the 2D maxillary superimposition .results as recommended by the American Board of Orthodontics. Results: Intra-class correlation will be used to test the intra-examiner reliability. The mean differences between the two 3D superimposition methods will be evaluated by the mean of color-coded maps. The angular and linear changes in the position of the upper right central incisor will be used to compare the 2D superimposition to the 3D methods used in this study.