Segmental mandibular reconstruction by microincremental automatic distraction osteogenesis: an animal study.

We investigated the reconstruction of a surgically created critical size mandibular defect in sheep using a newly developed automatic distraction device. The device has an implantable component, which is fixed to the mandible to allow the transfer of the transport disc across the created defect, and an external component which is mounted on the activation pump and secured away from the site of bone distraction. Compression of the bellows in the external component causes fluid to be forced through the connecting tube into the distraction component. Distraction at a rate of 1 mm over 24 h was achieved in six sheep. New bone generated at the site of the created defects both anterior (compression side) and posterior (tension side) to the transport disc and had similar radiodensity to the adjacent mandibular bone eight weeks after the completion of distraction.