Question: A 25 year old male is involved in an altercation and sustains mandibular fracture. CT reveals a significantly displaced parasymphyseal fracture and a contralateral angle fracture. He undergoes ORIF with a single reconstruction bar placed on the lower edge of the anterior mandible spanning the fracture line and a Champy plate for the angle. You see him after 2 weeks when he remarks that his chin has been numb. What nerve was injured? What tooth can be used as a landmark to locate it? [Answer will be posted with next week's new question]

Answer to last week's question, "Striking a Cord" (November 7, 2016):

Amyotrophic lateral sclerosis.