Leiomyosarcoma is a rare malignant condition occurring in the maxillofacial region in which the mandible may be affected. Management of this tumor in the mandible may include segmental mandibulectomy, osteocutaneous fibula free-flap reconstruction, endosseous implants, and postoperative radiotherapy. Posttreatment malocclusion can be managed with an overpartial mandibular resection prosthesis. The purpose of this report is to describe the expeditious oral rehabilitation of an oncologic patient with posttreatment malocclusion, demonstrating the utility of an overpartial mandibular resection prosthesis.