## 4 Discussion
This technology was demonstrated to be beneficial to both the clinician and the patient, reducing the preoperative planning time and overall surgical time. A surgical plan and surgical splint generated by a computer have the advantage that they can be shared with engineers from a Computer-Aided Design/Computer-Aided Manufacturing (CAD/CAM) center through the internet. Surgical splints can be fabricated by an additive manufacturing or milling technique and applied during surgery to transferthe virtual surgical planning to the operating field. For occlusal splints, previous studies have proposed the use of CAD/CAM occlusal splints as a reliable substitution to address the flaws of laboratory-based methods, including non-controllable errors, inter-laboratory differences, high costs, and time inefficiency [3]. Nevertheless, differences still exist between the virtual planning and surgical execution due to the complexity of movements and transfer of data throughout splints from the virtual planning to the surgery. The reliability and predictability of virtual surgical planning must be tested. In the literature, many studies have tried to evaluate the accuracy of virtual planning in orthognathic surgery using different protocols. These protocols and methodologies vary from linear/angular measurements, surface-to-surface differences, or virtual triangles. The most frequently used approach is linear and angular measurements, which rely on accurately identifying cephalometric landmarks and are prone to human error, especially when it must be done both on the preoperative and postoperative model [23]. Color-coded distances maps are visual analytical tools that display the distance between two 3D surface meshes and are generally included in most software. [PERSON] et al. [16] evaluated the accuracy of virtual planning based on the surface distance differences between the plan and the actual outcome on 11 different regions of the maxilla and mandible. The method was done using a surface-to-surface best fit of the two virtual models, aligning the base of the skull and measuring the distance between the planned and actual outcome post-operatively. They found no statistically significant difference between the simulated and the actual surgical models in all 11 regions of interest, with distances of less than 0.5 mm except for the left lateral maxilla (0.536 mm). In 2016, [PERSON] et al. [24] analyzed the accuracy of virtual surgical planning and 3D printed surgical templates in orthognathic bimaxillary surgery in 30 patients. They studied the linear and angular differences in different cephalometric points. The mean linear difference was 0.81 mm and the overall mean angular difference was 0.95 degrees. Furthermore, they found that 3D printed surgical templates worked better on the maxilla than on the mandible (0.71 mm vs. 0.91 mm for the mean linear difference) and showed better control of the deviation from the midfacial plane (0.55 mm) than the FHP (0.92 mm) and the coronal plane (0.97 mm). [PERSON] et al. [4] studied 30 patients who had undergone bimaxillary orthognathic surgery with and without segmentation and genioplasty, and found all mean linear differences for the maxilla, mandible, and chin segment to be within 0.5 mm. They also found that the mean precision, measured as the standard deviation, was smallest in the super-oinferior direction, followed by the mediolateral deviation, and finally, anteroposterior. Precision was also the most accurate in the mandible, slightly less in the maxilla, and least in the chin segment, probably due to the mandible-first sequence. [PERSON] et al. [25] and [PERSON] et al. [26; 27] quantified 3D displacement using the \(X\), \(Y\), and \(Z\) vectors of landmark displacement, similarly to our study. [PERSON] et al. [27] described methods referring to both linear and angular measures. However, these measures do not reflect what happens along the whole surface [28]. For this reason, color-coded maps are needed to display information on what is happening along the whole surface model.