Osteoradionecrosis (ORN), a pathological condition characterized by a nonvital bone occurring in the site of radiation injury, is one of the significant risks following extraction of highly impacted third molar teeth in patients treated with head & neck radiotherapy for oral cancer. Therefore, the surgery’s meticulous planning is essential to avoid such complications. This case report describes a 63-year-old male patient diagnosed with an impacted lower third molar (tooth #38) with concurrent basal cell carcinoma of the right ear and squamous cell carcinoma of the right vocal cord treated with radiotherapy. Taking into account the patient’s health status, a minimally invasive osteotomy and a corono-radicular separation procedure were performed. This procedure allowed us to reduce the risk of mandibular ORN. Three years later, the healing was complete, and the situation was stable.