CLASS II MALOCCLUSION: A NEW CHALLANGE FOR DISTRACTION OSTEOGENESIS

Mandibular lengthening by means of bilateral sagittal split osteotomy leads to excellent outcome if the discrepancy to be corrected is less than 10 mm. Results can be unpredictable when major mandible elongation is necessary. Immediate outcome can be compromised because of the limitation of the soft tissue which undergoes stretching during the one-step surgical procedure. A long term relapse is also considered more likely to happen when the discrepancy is relevant. Excessive soft tissue elongation is responsible for generating forces against the mandibular advancement leading to a relapse. Mandibular lengthening by means of distraction osteogenesis (D.O.) appears to be an interesting alternative for improving the immediate and long term outcome. D.O. leads to a progressive hard and soft tissue lengthening, allowing the mandibular bone, as well as the masticatory muscles, to elongate, slowly adapting to the new dimension and thus reducing the incidence of relapse. Class II malocclusion due to different mandibular pathologies were corrected by means of bilateral D.O. of the mandible bodies using intraoral devices. The distraction vector was planned by means of cephalometric analysis. Device positioning was performed using a specific “device positioning occlusal plate” as well as “ class II devices” to achieve perfect parallelism between the two devices and to avoid any incorrect orientation of the sagittal plane. Distraction protocol was: a latency period of 4 to 7 days, a distraction rate of 0.8 mm/day, a stabilisation period of 2 to 4 months. No major complications occurred. Orthodontic treatment, specifically adapted to this type of treatment, was performed before distraction and for about 6 months after. A genioplasty was performed when the devices were removed. Clinical and radiological results are presented. D.O. confirms to be an interesting new possibility in the treatment of the severe class II malocclusion.