Purpose The purpose of this study was to evaluate the complications associated with the use of reconstruction plates with or without non-vascularized bone graft in reconstruction of mandibular segmental defects caused by trauma and tumor resection and to analyze various factors that are associated with the development of complications. Methods A retrospective observational study was conducted, and the investigated variables included the age and gender of the patients, etiology of the defect, the site of the defect, the size of the defect, whether bone graft was used or not, type of plate used, and whether the reconstruction was immediate or delayed. The outcome variables were the postoperative complications and the success rate. Results Fifty-one patients were enrolled in this study; the etiology of mandibular defect was trauma in 39 patients (76.5%) and resection of benign or malignant tumors in 12 patients (23.5%). The complication rate was (58.8%) and the success rate was (94.1%); the only factor that significantly increased the incidence of postoperative complications was the size of the defect. Conclusion Reconstruction plates demonstrated a high success rate despite the high complication rate. Segmental defects caused by trauma were smaller than those created after tumor resection and the only factor that increased complication rate was the size of the defect; other factors did not affect the complication rate.