This is Episode fourteen: Oral Cavity Four — Mandible, Reconstruction, and Bone Invasion Pitfalls.In the previous three episodes, we covered oral cavity anatomy, surgical management, the neck decision, and adjuvant therapy principles. Now we need to tackle what happens when the mandible is in play—and it often is.The mandible is the elephant in the room for oral cavity radiation. Floor of mouth tumors sit directly against the lingual cortex. Lower alveolar ridge cancers arise from the gingiva overlying the bone. Retromolar trigone tumors can extend to the ascending ramus. Even oral tongue cancers can invade the mandible through the floor of mouth.Understanding mandibular anatomy, invasion patterns, surgical options, and osteoradionecrosis prevention is essential for any radiation oncologist treating oral cavity cancer. This episode covers the practical planning considerations you'll face when bone is involved.After this episode, you should be able to answer: When does the mandible require full-dose coverage versus sparing? What drives ORN risk dosimetrically? And what changes when there's a reconstruction flap in the field?Let's get into it.