## 4 Discussion
In their systematic review, [PERSON] et al. [29] analyzed 12 papers regarding the accuracy analysis of virtual surgical planning. The accuracy values for the pitch, yaw, and roll (\({}^{\circ}\)) were (<2.75, <1.7, <1.1) for the maxilla, respectively, and (<2.75, <1.8, <1.1) for the mandible. They observed that the calculation of the linear and angular differences between the virtual plans and postoperative outcomes was the most frequented method used for accuracy assessment, and a difference of less than 2 mm/\({}^{\circ}\) was considered acceptable. They concluded that virtual planning appears to be more accurate, especially in terms of frontal symmetry, similar to our results. On the other hand, [PERSON] et al. [7] used a different method for validation and accuracy of results in bimaxillary orthognathic surgery. They used a tool called \"OrthoGnathicAnal-yser\" to analyze the postoperative outcomes with regard to the virtual planning. The main difference lies in the fact that no landmark identification is needed because the relevant translational and rotational movements of each jaw segment could be computed from the rotation matrices of the jaw segments during the registration process using the OrthoG-nathicAnalyser tool. They found that the left/right translation showed the lowest absolute mean difference between the 3D planning and the surgical result for both the maxilla and mandible, at 0.49 mm, and 0.71 mm, respectively, whilst the vertical positioning of the maxilla and mandible suggested the lowest accuracy. In line with previous studies, the interoclusal wafer provided less intra-operative control in the vertical dimension. The method we applied in this study can express more 3D shape information in comparison to those that were based solely on the calculations of linear and angular distances, offering valuable information in the three axes and three dimensions for the cephalometric points selected and visual data in the color-coded maps. In the literature, differences of less than 2 mm between the virtual surgical planning and the actual postoperative results have been considered clinically acceptable by many authors [4; 16; 30]. However, we believe that this statement must be taken cautiously since it highly depends on the quantity of movement (an advancement of 4 mm is not as clinically irrelevant as 8 mm). In this study, overall good accuracy was found, with all differences for point A, point B, Pog, and both the upper and lower first molars being below 1 mm. The greatest values for the rest of the landmarks were found in the y (anteroposterior) axis at point A (0.835 mm), point B (0.480 mm), and Pogonion (0.780 mm), with overall worse accuracy in the anteroposterior direction for all the landmarks studied. On the contrary, distances found in the mediolateral direction were low (0.239 mm for point A, 0.070 mm for point B, and 0.079 mm in Pog). This means that the accuracy provided by intraoperative interoclusal splints is good in the mediolateral direction but poorer in the anteroposterior direction. The authors believe this can be explained because the thickness of the splint is considerable, and the segments may slide and be minimally displaced in the anteroposterior direction. Higher differences in the anteroposterior direction may also be explained because the magnitude of movement in this plane is usually the greatest when performing orthognathic bimaxillary surgery. Vertical distances were also low (<0.3 mm), with the lowest at point B (0.150 mm) and slightly higher at point A (0.280 mm). The latter is manually controlled by the surgeon by measuring the distance from a bone-fixed point (a screw at the nasion in this series) and not by the splint, which may explain the higher difference. The differences in the bone located over the upper first molars were found to be higher compared to those of the mandibular first molars.