Landmark-Based Versus Voxel-Based 3-Dimensional Quantitative Analysis of Bimaxillary Osteotomies: A Comparative Study

Abstract

We compared the accuracy of landmark-based and voxel-based 3-dimensional (3D) analysis to quantify the osseous movements of the maxilla and mandible after bimaxillary osteotomy. Cone beam computed tomography (CBCT) scans of 15 patients who had undergone bimaxillary osteotomy were randomly selected from the database. Before surgery, CBCT scanning was performed and an individualized 3D virtual surgical plan made for all patients. During surgery, the mandibular and maxillary segments were positioned as planned using 3D-milled interocclusal splints. At 1week after surgery, a postoperative CBCT scan was acquired. All pre- and postoperative CBCT data were rendered in 3 dimensions. The 3D virtual head models were superimposed on the cranial base. The 3D surgical movements of the maxilla and mandible were quantified using conventional landmark-based 3D cephalometric analyses and voxel-based 3D analyses (OrthoGnathicAnalyser). This process was performed by the same observer 3 times. The intraclass correlations and Bland-Altman plots were computed to quantify the measurement errors and reproducibility of both methods. High intraclass correlation coefficients were found for both methods. The voxel-based analyses yielded a higher correlation concerning the maxilla and distal mandible (r=0.98) compared with the landmark-based cephalometric analyses (r=0.90). The use of voxel-based 3D analyses in the quantification of osseous movements was more reliable and reproducible than the use of conventional landmark-based 3D analyses.