Background: Traditionally, landmarks are used as reference to plan correction of facial asymmetry. However, there are errors associated with the landmarks and doubts exist as to whether the landmarks can represent the structures.

Materials and methods: Optimal symmetry planes were established for the midface and the mandible. They were aligned so that the planes were close to each other while at the same time keeping the occlusion acceptable. This process was undertaken with help of navigation technology. A total of 18 patients had undergone such planning and surgery had been performed accordingly. The surgical outcome was analyzed. A deflection of mandible over 4 mm or 4° was defined as having residual asymmetry.

Results: Postoperatively, 4 patients were found to have residual asymmetry. One patient showed increase in both mandible deviation (4.9 mm and 4.7°); while 1 showed a deviation distance of 4.1 mm and another showed a deviation angle of 4.3°. Their deviation of mandible before surgery varied from 14.2 mm to 16.7 mm. The reasons for the residual asymmetry included major occlusal interference, surgical imprecision, and relapse. Conclusions: All patients demonstrated mark improvement in facial asymmetry. This method may improve the outcome of facial bone asymmetry correction. This planning method has 4 advantages: (1) capable of simulating all kind of jawbone movement; (2) preview of outcome in 3D; (3) negotiate optimal occlusion and symmetry in a convenient way; (4) preserve the usual practice of clinicians in determining the final occlusion.