Evaluation of the Dimensional Changes in the Mandible, Condyles, and the Temporomandibular Joint Following Skeletal Class III Treatment with Chin Cup and Bonded Maxillary Bite Block Using Low-Dose Computed Tomography: A Single-center, Randomized Controlled Trial

Linear and angular measurements A new template was created from the Measure and Analyze tool of Mimics™, which was used to define the anatomical landmarks and planes and produce the desired measurements. Ikeda and Kawamura suggested that the condylar and glenoid fossa landmarks were made on the corrected sagittal view. After identifying the landmarks, the software automatically calculated the distances and the angles. Then, the data was exported in .cvs format. 3D mandibular regional superimposition and comparison analysis: The paired resulting reconstructed mandibular models were exported to 3-Matic software (3-matic13.0, Materialise NV, Leuven, Belgium), and their surfaces were warped using the Warp tool of Mimics™. Initially, The T1 and T2 3D volumes were superimposed manually by approximating similar anatomical regions of the mandible using Interactive Translate and Rotate tools of the software, followed by automatic global registration in 3-Matic software. The superimposition was repeated three times to enhance accuracy and reproducibility. The point-based analysis was performed to assess the changes in 3D mandibular models between T1 and T2, and a color map was produced to assess the mandibular shape changes. The threshold was set at 2 mm: green areas indicated differences within 2 mm (between −2 and 2 mm), red surfaces indicated positive values displacement more than 2 mm, and blue surfaces indicated negative values displacement greater than −2 mm between two 3D models. Quantitative changes were done by reporting the mean, minimum, and maximum values of part analyses on a spreadsheet and used for comparative analyses.