Feasibility of internal curve distractor of the zygoma for maxillary segmental reconstruction

Xuegang NIU; Xiaoxian HAN; Yong HAO

ABSTRACT

BACKGROUND:

The functional reconstruction of large maxillary defects is a significant challenge due to the lack of bony support.In this paper.a new approach for segmental maxillary reconstruction and bony support foundation is put forward and tested by animal experiment.

OBJECTIVE:

To evaluate the possibility of segmental maxillary regeneration by internal curve distraction osteogenesis of zygoma with the self-developed distractor.

DESIGN:

Animal experiment.

SETTING:

Department of Stomatology.the 252 Hospital of Chinese PLA.MATERIALS Two healthy female hybrid canines of 1-1.5 years old and 20-25 kg were selected. Internal curve distractor was composed of three partscurve track,movable part and a flexible central thread bar fixed at the center of the curve track.The former two parts,which was made of TC4,(Ti-6AI-4V),and the flexible central thread bar was made of nickel titanium wire. A 360° of counter clockwise rotation of the distraction activator achieved an advancement of 0.35 mm for the movable part;the maximum distraction length allowed by the distractor was 25 mm.

METHODS:

The experiment was carried out in the animal experimental center of Fourth Military Medical University of Chinese PLA from October 2003 to February 2004. The segmental defect of 18-20 mm in width was made in maxilla and zygoma to simulate maxillary defects.Then an osteotomy distal to the defect was performed to create the variable transport disk. The distractor was fixed to the residual zygoma and zygomatic arch for internal curve distraction osteogenesis.After a latency period of 5 days,the distraction started at a ratio of 1.05 mm per day (0.35 mm once,3 times per day) for 13 consecutive days. Before and after distraction and at the second, fourth and eighth week of consolidation, the bone radiographs of residual zygoma and zygomatic arch were taken routinely.MAIN OUTCOME

MEASURES:

The general condition of the animals and distractor, and the quality and quantity of new formation bone in the distracted gap.

RESULTS:

Canines and distractor were in good condition during the experimental period.X-ray film showed that at the end of distraction, the bony transport disks were distracted about 12 mm around arc.At the 8th week of consolidation,the density of new bone was close to that of normal bone,and the curved bony regeneration was almost completed.

CONCLUSION:

The serf-designed curve internal distractor is fit the condition of major maxillary defects,and could be used for the internal curve distraction of zygoma.