This case shares about the outcome of PSI in large sized lesion of the Mandible and Our experience regarding the factors leading to the failure of Patient specific Implants. The Patient was suffering from odontogenic keratocyst, extending from right side angle to left side angle of the mandible. After segmental mandibulectomy, Patient Specific Implant was delivered. Thereafter 1 month, PSI was exposed and got infected. On the next step, we retrieved the PSI and did microvascular free fibula flap for reconstruction of jaw. This paper focuses on the scope of improvement for mandibular reconstruction by Patient Specific Implant.