Background: Three-dimensional virtual surgical planning (Three-dimensional VSP) has become standard practice in the treatment of mandibular oral squamous cell carcinoma (OSCC) in the last decade. Dutch guidelines recommend a care pathway interval (CPI) of a maximum of 30 days, and a free bone margin of at least 5 mm. Fused MRI and CT data are used for accurate tumor delineation. Based on this data, a virtual surgical plan is created and transferred to the operating room using resection guides and patient-specific implants (PSIs). Long-term evaluation is needed to further optimize its clinical use. Objectives: This study evaluates adherence to bone margin and CPI guidelines in mandibular OSCC. Additionally, it assesses the accuracy of tumor resection and reconstruction using 3D-VSP and compares the complications of 3D-planned mandibular reconstruction using different kinds of osteosynthesis plates. Methods: All patients who underwent a segmental mandibulectomy between 2014 and 2024 at the University Medical Center Groningen were included. CPI, clinical outcomes, and complications were analyzed. The preoperative virtual plan was compared with the postoperative outcome to assess accuracy. Results: The median CPI was 34 days, and 93.7% of bone margins were tumor-free. Mean absolute resection deviation was 1.63 mm (±1.42). PSI reconstructions were significantly more accurate in intergonial distance and coronal angle compared to conventional plates. Plate-related complications were more common in non-bony reconstructions; PSI reconstructions showed significantly more plate exposure. Conclusions: 3D-VSP leads to high accuracy in resection and reconstruction and favorable bone margins. Shortening the CPI and reducing biological complications are essential to further improve oncological outcomes.