## 4 Discussion  
Virtual surgical planning enables the precise analysis of a 3D model that represents the clinical situation and facilitates diagnosis and treatment planning [18,19]. Since [PERSON] [19] initiated 3D cephalometric analysis and treatment planning, 3D virtual planning has replaced 2D cephalometric analysis. Recent trends in orthognathic surgery have evolved to minimize the period of pre-operative orthodontic treatment and to combine 3D technology in the process of surgical planning to improve accuracy [2]. Several technological advances are being used widely to reduce preoperative planning and surgical operating time, including CAD/CAM technologies, 3D printing, intraoperative navigation, and augmented reality. Using 3D virtual models, all the procedures for diagnosis and surgical splint production can be simulated, intermediate assessment can be conducted, and the intermediate and final surgical splints can be produced. Therefore, errors encountered during laboratory procedures are minimal [20]. Virtual surgical planning has facilitated accurate diagnoses and detailed treatment planning through better visualization of 3D phenotypic changes [2]. In addition, virtual surgical planning allows for soft tissue evaluation and prediction. Available virtual planning software, such as Dolphin (Dolphin Imaging & Management Solutions, Chatsworth, CA, USA) or Maxilim (Medicim NV, Mechelen, Belgium), allow for an approximate prediction of the soft tissue response after maxillomandibularbular repositioning as a simple geometric transformation, not considering accurate mechanical modeling and tissue properties. Multiple studies have analyzed computational models of soft tissue prediction in orthognathic surgery, using complex finite element analyses and algorithms. [PERSON] et al. [21] studied 10 patients who underwent orthognathic surgery and presented a simulation methodology for the planning of orthognathic surgical interventions, paying special attention to soft tissue simulation. The handling of several tissue couplings, i.e., soft tissue and bone, demonstrated a high complexity, which requires high-resolution meshes and long computation times to ensure accurate results. Furthermore, they found a tendency toward negative/cold errors, which was slightly higher on coarse meshes. Furthermore, the use of 3D printed surgical guides and pre-bended fixation plates on 3D printed models based on virtual surgical planning increases the accuracy of the performed osteotomies and repositioning of the bone segments, shortening surgical time and improving the overall surgical results [2,3]. The use of 3D printers in orthognathic surgery is widely extended and includes the production of splints, surgical guides, pre-bend plates, patient-specific implants and plates, and 3D models. Compared to the traditional method, the digital-based occlusal splint provides high accuracy, reliability, and consistency, as well as improved quantitative control and efficiency [3]. Numerous studies have demonstrated that 3D printing technologies help the clinician shorten the operative time, increase surgical safety, and improve the predictability of surgical outcomes [3]. [PERSON] et al. [22] used an intraoral digital scanner to obtain surface images of the dental arches. After fusing the scans with the CBCT images of the patients for CAD/CAM intermediate splint generation, the accuracy and reliability of the protocol were assessed, showing an error below 1.5 mm between the virtual intermaximillary position and the intraoperative intermaximillary relationship and revealing a high overall accuracy. [PERSON] et al. [3] performed a systematic review regarding applications of 3D printed technology in orthognathic surgery. They identified 78 articles where different applications were described. They found that most articles described the use of occlusal splints, osteotomy/cutting guides, positioning guides, spacers, fixations plates/implants, and 3D printed models.