DISTRACTION OSTEOGENESIS IN THE IRRADIATED CANINE MANDIBLE

The potential use of distraction osteogenesis in mandibular reconstruc tion has been limited by its questionable efficacy in previously radia ted bone. We studied five mongrel dogs that had a hemimandible rendere d edentulous and underwent a full course of external beam radiation th erapy (50 Gy/20 fractions). Six months after completion of radiotherap y, a 2-cm critical-size segmental mandibular defect was created and st abilized with a stainless steel plate. A proximal mandibular transport segment was then formed and an external lengthening apparatus (Orthof ix) applied. By means of bifocal distraction osteogenesis, the defects were filled with new bone in a period of 30 days in four of five dogs . Histologic analysis and fluorochrome microscopy confirmed the format ion of new cortical bone. Our results suggest that distraction osteoge nesis is successful in previously radiated bone and that it may be a s imple method of mandibular reconstruction following ablative head and neck surgery.