Orthognathic surgery is a surgical procedure performed to correct dentofacial deformities. In recent years, with the use of virtual surgical planning, cutting guides, and patient-specific osteosynthesis plates, highly predictable results can be achieved. While there are many positive reports regarding the use of patient-specific plates in maxillary positioning in orthognathic surgery, there is a lack of sufficient studies comparing the results obtained in mandibular positioning. Additionally, numerous designs of proximal segment positioning devices have been published, but comparative studies on their effectiveness have not been conducted. Therefore, a study comparing these approaches has been planned.