A comparison of gradual distraction techniques for modification of the midface in growing sheep.

The authors carried out experiments to advance the midface in growing sheep using a distraction force across the zygomaticomaxillary sutures. They wished to assess the possibility of performing distraction osteogenesis across intact sutures as well as distraction after Le Fort osteotomies. Their results demonstrate that the technique of gradual distraction after osteotomy is successful in the growing animal. Bilateral distraction across intact sutures did not advance the midface or change the dental relationship. Unilateral distraction was successful in angulating the midface away from the distracting force in the intact growing animal. Alternating unilateral distraction or "waltzing" was surprisingly effective in advancing the midface in one of the animals studied and may become applicable in some craniofacial deformities. In all intact animals there was some expansion of the zygomaticomaxillary suture as well as a substantial migration of the distraction devices through the bone.