## 4 Discussion
Again, the authors believe this difference may be explained by the fact that surgery is performed in a mandible-first sequence, and a final splint to position the maxilla is not used and it is positioned manually instead. Regarding the 3D distances, the highest difference was found at Pog, with the lowest at point B, where the highest accuracy was found. When performing the multivariate analysis to examine the influence of each axis on the overall 3D distance, it was observed that for point A and Pog, it was the \(y\) axis (anteroposterior) that showed the greatest coefficient, meaning that for point A and Pog, the anteroposterior direction had the strongest influence on the overall 3D distance. Thus, it was in the anteroposterior direction that accuracy was the lowest. On the other hand, for point B, it was the vertical axis that had the highest effect on the 3D distance. In conclusion, we found that in this study, the positioning of the mandible compared to the maxilla was more accurate. In addition, the lowest accuracy was found in the anteroposterior direction, whilst the highest accuracy was observed in the mediolateral direction. Further studies are needed to determine if future refinements of interoclusal splints may improve these results. Furthermore, in the vertical direction, all median differences were very accurate, especially in point B, where the distances were the lowest. Vertical distances were the highest at point A, which is intraoperatively controlled by the surgeon by osseous references and may explain these results. Differences in the mediolateral direction were also low for point A, point B, and Pog, reflecting a high accuracy when positioning both the maxilla and mandible in the midline, especially the mandible. The authors believe that a mandible-first sequence allows the surgeon to overcome and correct problems of the centric relation and achieve a more predictable position. It is less prone to errors caused by the incorrect position of the mandible during CBCT examination. Special attention is paid to properly seat the condyles in the fossa during the stabilization of the proximal segment of the mandible and fixation since maxillary position can be inaccurate if the mandible is not correctly positioned. The authors' preference is also not to use the final splint, and the maxilla is positioned according to correct dental interdigitation and occlusion, therefore eliminating interferences from the splint. However, a palatal splint is used in cases of segmental maxillary surgery. It is important to consider this when discussing these results. Regarding the limitations of this study, it is a retrospective study and, as stated by many authors, the need for a manual selection of the cephalometric landmarks for analysis, which need to be identified multiple times on the models, is prone to human error and may be a source of inaccuracy in this study. Two solutions can be provided to overcome the landmark identification bias--either the fully automated identification of landmarks or the elimination of cephalometric landmark identification, as proposed by [PERSON] et al. [7]. Another source of limitation may be correlated to erroneous data on the surface mesh (for example, streak artifacts or surface roughness), which would have a marked effect on the measurements [31]. In addition, postoperative CBCT was acquired without the use of the final splint. This may lead to a different occlusion than planned due to occlusal interferences, showing higher differences between the 3D planned and surgically achieved mandibular position. As improvements to this study, measurements in more cephalometric and dental landmarks could be taken to conduct a more exhaustive and detailed analysis. Different assessment methods could also be used to overcome observer-dependent landmark identification errors. It would also be interesting to analyze these results considering the quantity of movement performed and display these results as percentages.