# Wafers Orthopathic Surgery with Customized Osteosynthesis and Surgical Guides: A Prospective Study
## 4 Discussion
Previous studies have reported that deviations of <2.0 mm in the maxilla are clinically insignificant [12; 26; 27]. In contrast, inaccuracies of >1.0 mm in the anterior maxilla could result in undesirable positioning of the maxillary midline, which could lead to a undesired aesthetic consequences for the patient [13; 14; 28]. On the other hand, discrepancies of 2 mm traditionally have been considered acceptable, as they may be resolved through orthodontic treatment [20]. Our results demonstrated a mean overall (all 18 landmarks and three axes) deviation of <1 mm which, to our knowledge, is consistent with the results of other published articles [13; 14; 16; 21; 23; 24; 25]. We performed a segmented analysis of maxillary, mandibular and chin landmarks, evidencing greater accuracy in the maxilla than in the mandible or chin. These discrepancies could be explained by different situations such as positioning of the mandible during the CT scan, the timing of the CT scan after OS, or the orthodontic treatment carried out at the time of the CT scan. In our opinion, the most important issue when performing guided OS is to secure precise positioning of the maxilla. No surgical guides were used in the present study for the mandible or SSO. We consider that there are many reasons for not using guides in the mandible. Nevertheless, no studies have been found reporting significant improvements with the use of CMSGs and CMTPs for the mandible. Positioning of the mandible may be affected by factors such as the condyle position, bone interferences, occlusal interferences and the type of osteosynthesis. All these variables need to be managed by the surgeon during surgery. In this regard, leaving all such variables in the hands of a surgical guide and moreover in a defined plating system, could affect the final results. Maxilofacial surgeons need to take all these aspects into account when performing mandibular OS. Condyle positioning and mandibular osteosynthesis form part of the art of OS, and should be managed by experienced surgeons. The present study was designed evaluating variables in the maxilla, mandible and chin. In this regard, CMSGs and CMTPs were only used in the maxilla and chin. We expected less accuracy in the mandibular and chin landmarks, due to possible variations in mandibular position when performing the CT scan. Even considering this possible bias, the mandibular and chin landmarks yielded significant results when a deviation of >2 mm was taken to be the maximum acceptable deviation, as described in the literature [12; 26; 27]. In any case, we found positioning of the maxilla to be accurate to <1 mm (0.72 mm, SD = 0.75). This is the real accuracy that can be achieved when positioning the maxilla, following the virtual guided treatment plan in the hands of a surgical team experienced with customized procedures in maxillary OS. A potential additional problem in waferless mandibular positioning is the position of the condyle during the preoperative CT scan, which is the basis for computer-assisted planning of mandibular bone segment positioning. In computer-assisted planning of waferless mandibular positioning, the condyles must be in the centric position during scanning. From our perspective, this is difficult to achieve in many cases, even when wearing a relaxation splint for several weeks before the preoperative CT scan is made. In our opinion, no better protocol is available when performing OS, though each surgical team should assess its own protocol to understand and improve the clinical results obtained. OS has a great impact on individual's face features which can positively impact their mental, emotional, and psychosocial health over time [29; 30]. This is something paramount to consider when evaluating the importance of promoting and achieving the most accurate and predictable results possible. CAD/CAM surgery of the maxilla can be performed not only as a maxilla first protocol. Considering the level of accuracy achieved in our study, a mandible first with an intermediate splint protocol could also be used.