## 4 Discussion  
Various CAD/CAM templates based on 3D surgical simulation have been developed to overcome limitations in the use of the intermediate splints in orthognathic surgery [1; 3; 6; 18; 19; 20; 21; 30; 34]. The CAD/CAM templates are designed on 3D virtual skull models generated from CT data, and are fabricated using 3D printing technology, or they are milled from titanium alloy blocks. During surgery, repositioning of the bony segment to the planned position can be accomplished accurately only when the template is located in the exact position deduced from the surgical simulation. When the template is not fixed in the planned position, subsequent procedures including osteotomy, removal of bone interference, and repositioning of the bony segments may be different from those obtained by the surgical simulation. In addition, the final surgical outcome can also be different when compared to the planned and predicted outcome. Depending on the method used for fitting the template, the templates can be divided into two systems: (1) dentition-based system and (2) surface-based system. The dentition-based system includes the occlusal splint, which can provide a more accurate reproduction of the template position during surgery [2; 9; 21]. However, this system requires scanning of the dental cast and registration of the scanning data into CT data, which can be time-consuming and error-prone. Furthermore, undesirable preoperative tooth movement after impression and scanning of dentition may lead to generation of inaccurate templates. In the surface-based system, reproduction of the template position can be achieved by maxillary surface configuration without an occlusal splint. Thus, scanning of dental cast and data registration are not necessary [1; 3; 18; 19; 20; 30]. Although the bulky template can result in distortion of period soft tissue, which makes it difficult to evaluate soft-tissue changes during the surgery, this system requires a template that covers its underlying bone surface as widely as possible and includes characterized anatomical structures. Several previous studies reported successful surgical results after orthognathic surgery with surface-based CAD/CAM templates [3; 18; 19; 30]. [PERSON] et al. [30] proposed a technique using a pair of surface templates that records the 3D surface geometry of the region of interest as an alternative to the intermediate surgical wafer and reported that the templates fitted intimately with the outer surface of the maxilla. [PERSON] et al. [19] used laser-sintered PSI as a positioning guide with concurrent rigid fixation after Le Fort I osteotomy and reported minimal inconsistency between the planning and postoperative results in quality analysis. [PERSON] et al. [18] used bone-supported guides for placement of the custom-machined titanium miniplates fabricated using CAD/CAM technology in six patients. They reported that the plates fitted perfectly with the anterior buttress of the maxilla and the surface of the mandibular body during the surgery. In their study, the average surface deviation between the presurgical plan and the final surgical results was 1.09 \(\pm\) 0.78 mm (71.2% of values within