[Mandibular fracture: an unusual complication following osteotomy of the chin].

A case of a median mandibular fracture with extensive osteolysis 8 weeks following a reduction and protrusion genioplasty is reported. A porous hydroxylapatite block, Interpore 200, was used for contour augmentation at the labiomental fold. The weakening effect of the osteotomy, a foreign body-related chronic osteomyelitis, and repetitive angulation of the mandible during mastication play a role in the pathogenesis of this fracture. Treatment consisted of removal of the porous hydroxylapatite block, removal of the screws and plates, surgical debridement of the necrotic tissue, antibiotics, and immobilization with an arch bar on the buccal side and a lingual acrylic splint to prevent rotation of the upper border of the mandible. Healing was uneventful, without loss of teeth.