Distraction osteogenesis for reconstruction of mandibular symphyseal defects

We investigated the feasibility of arched trifocal distraction osteogenesis for reconstruction of mandibular symphyseal defects.

Four adult canine subjects were used. An external apparatus was designed to allow trifocal distraction around an arc. An anterior mandibulectomy was performed between the third premolars bilaterally. The bony defect was regenerated using trifocal distraction osteogenesis at a rate of 1 mm a day bilaterally. New arced bone was produced over a period of 20 to 35 days. The apparatus functioned as an external fixator for the ensuing 6 weeks. The apparatus was then removed, the dogs were returned to their preoperative diet, and were killed after 2 weeks of observation.

Grossly a smooth arc of bone was formed measuring 4.5 to 5.5 cm in length, 2.2 to 3.0 cm in height, and 1.3 to 1.5 cm in width. Histologically all specimens demonstrated direct membranous bone growth. Radiographically opaque columns were seen streaming in the direction of distraction.

Symphyseal bony defects resulting from oncologic resection, trauma, and congenital deformities create tremendous cosmetic and functional handicaps and have remained extremely challenging to surgically reconstruct. This study demonstrates the ability to use arced trifocal distraction osteogenesis to reconstruct anterior mandibulectomy defects in a canine model. This method may provide a satisfactory solution to a difficult problem in human mandibular reconstruction.