[Peripheral facial paralysis caused by an orthognathically-designed osteotomy in a Class III malocclusion].

Sagittal split ramus osteotomy creates an internal and an external valves. In an 18-year-old girl with class III dysmorphism, a bone spur on the internal valve compressed the facial nerve during the mandibular setback, leading to facial palsy after three days. We propose a surgical procedure and discuss short-term and long-term outcomes.