Reconstruction of mandibular defects after trauma or tumor resection is one of the most challenging problems facing by maxillofacial surgeons. Few mandibular defects require not just a fixation of an implant, but the reconstruction of the entire mandible. The aim of this study was to design a mandibular prosthesis for a mandibular cancer patient and study its efficacy by stress–strain related mechanical property using finite element analysis (FEA).