| Objection: Mandibular elongation by gradual distraction in patients with hemifacial microsomia is a simple and effective procedure to correct facial asymmetry. The two-pin system joined by a softer distracting screw achieves elongation in vertical and sagittal directions as well as medial rotation. The changes in mandibular shape result in changes in dental occlusion. These are minimal in children because of the rapid growth of the maxilla and can be corrected easily with minor orthodontic work. Mandibular distraction in adults with hemifacial microsomia, who usually have stable dental occlusion, produces good aesthetic results but also severe alterations in the occlusion requiring complex orthodontic treatment over a long period. To avoid this problem, an incomplete Le Fort I osteotomy is done simultaneously with the mandibular corticotomy. Intermaxillary fixation is done on the first postoperative day, and distraction is initiated. The objection of this report is to find a feasible and effective procedure to treat the cranial maxillary malformation in adult.Method: Under general anesthesia, an incision is made along the upper buccal sulcus and is extended to the first morlar on both sides. By subperiosteal dissection, the anterior and lateral aspects of the maxilla are exposed to the level of the pterygomaxillary junction. The nasal spine is exposed, and the subperiosteal undermining is extended along the floor and the lateral walls of the nose. With a reciprocating saw, a complete horizontal ostotomy is made on the maxilla at the level of the nasal floor, leaving the nasal spine and the septum intact. The pterygomaxillary junction is freed with a curved chisel on the affected side only. At this time, the maxilla remains fixed to the septum and to the pterygomaxillary suture on the unaffected side, which will serve as a pivot point for the midface rotation. Rowe forceps may be used softly to assess the completeness of the osteotomy, but no attempt is made to mobilize the midface. A second incision 5 cm long is then made on the inferior buccal sulcus on the affected side at the level of the ascending ramus. The periosteum is elevated, exposing the bone from its anterior edge behind the last molar to the genial angle and the surrounding area. Using a side-cutting burr, a corticotomy is made on the lateral aspect of the mandible until the cancellous layer is exposed. The external corticotomy is extended across the anterior and posterior edges of the mandible, especially posterior, where the bone is thicker. A part of the internal cortical layer remains intact. Two group intraosseous pins areintroduced percutaneously through the full thickness of the mandible 5 to 15 mm in front of and behind the corticotomy. The pins should be inserted parallel to each other to facilitate fixation to the distraction device. The relative location of the pins on the mandible determines the vector of the distraction forces and therefore the direction of maximum elongation of the bone. The buccal mucosa is closed, and the distraction device is fixed to the pins. Two days later, intermaxillary fixation is achieved with rigid material, and mandibular distraction is initiated at a rate of 1 mm per day. The face tent to be symmetrical, and the occlusal plane horizontal. At that time, the distraction is discontinued, but the pins and the joining screw are left in place for another 4 to 6 weeks until radiological evidence of new mandibular bone formation is obtained. Result: In this case, the maxilla was distracted simultaneously with the mandible, preserving the preexisting stable occlusion. Preoperative deviation of the occlusal plane was almost corrected. The plane tended to be horizontal. The distance from the inferior orbital rim to the occlusal plane on the affected side was increased.Conclusion: Simultaneous mandibular and maxillary distraction in adult is an effective treatment for hemifacial microsomia without the occurrence of the disaster occlusion. |
PDF Full Text Request