## 4 Discussion  
This preliminary study investigated the application of computer-aided surgical planning with patient-specific devices in DCIA free-flap mandibular reconstruction. Our primary objectives were to evaluate the accuracy of this approach and assess the clinical outcomes in a series of five patients. The results demonstrated promising accuracy with a mean deviation of 0.73 \(\pm\) 0.23 mm between the VSP and actual outcomes, along with a 100% flap survival rate. Though we encountered one case of hardware complication requiring plate removal, this led to valuable modifications in the plate design for subsequent cases. Our findings, while preliminary, suggest that this technique can achieve precise outcomes in both primary and revision cases, addressing a significant challenge in mandibular reconstruction. While mandibular reconstruction using DCIA flaps offers advantages such as a sufficient bone height and natural mandibular contour reproduction, meticulous surgical planning is required due to the complex donor site bone morphology and limited pedicle length. In particular, Case 1, our representative case, required the use of the contralateral iliac crestal bone due to a previous failed DCIA flap reconstruction. This resulted in the internal oblique muscle attachment site being positioned on the buccal aspect, where the reconstruction plate needed to be fixed. Consequently, the iliac bone trimming had to accommodate the muscle tissue, making it impossible to pre-plan the trimming area. This factor likely contributed to Case 1 showing the highest average and maximum errors, though the accuracy achieved can be considered satisfactory given these circumstances. The lowest average error was observed in Case 5 (0.32 mm), while Case 1 showed the highest average error (0.97 mm). Regarding the maximum deviations, Case 1 exhibited the highest value at 7.83 mm, though its average error remained relatively low at 0.97 mm. The standard deviation of the surface measurements ranged from 0.52 to 1.33, indicating consistent precision across different regions of the reconstructed mandible. Notably, Case 5 demonstrated the highest accuracy, which can be attributed to its unique characteristics as a marginal mandibulectomy case where the mandibular inferior border was preserved, and the reconstruction span was the shortest at 29 mm. This patient also showed the most favorable clinical parameters, including a shorter operation time, minimal blood loss, and a reduced hospital stay, suggesting that the preservation of the mandibular continuity and smaller defect size may contribute to both improved surgical accuracy and better clinical outcomes. During the study, one case developed screw loosening during the three-month follow-up period, necessitating the removal of the one plate. Concluding that four-hole reconstruction plates provided insufficient stability, we modified subsequent designs to include more holes (Figure 8), after which no additional complications occurred. The use of patient-specific surgical guides and plates significantly improved both the operative time efficiency and surgical predictability. As demonstrated in Case 1, successful reconstruction was achievable even in cases of previous reconstruction failure, validating the reliability of this approach. Furthermore, the use of surgical guides enhanced the accuracy of the DCIA flap harvesting, minimizing donor site defects and enabling ideal bone segment acquisition. According to [PERSON] et al., patient-specific mandibular reconstruction plates are superior to hand-molded plates and can provide the missing link in the virtual workflow of computer-assisted mandibular free-fibula- flap reconstruction [24]. The plates eliminated the need for plate bending either preoperatively or intraoperatively, reducing the potential for fatigue fracture while enabling precise reconstruction. [PERSON] et al.