2/3 osteotomy for lengthening the mandible in dogs by gradual distraction.

Successful lengthening of the mandible by gradual distraction has been reported previously. There are various methods for osteotomy before distraction osteogenesis. In this paper, a new type of osteotomy, performed on growing dogs as a model, is reported. Ten mongrel dogs, aged 6 months, were studied. A unilateral 2/3 osteotomy was performed, and an external lengthening device was fixed to the mandible perpendicular to the osteotomy. Seven days after the operation, the mandible was lengthened by 1 mm per day. The dogs were sacrificed for histological study at the end of the distraction on days 14, 28, 56 and 120 following completion of the distraction.