Precision of orthognathic surgery. A computerized cephalometric analysis of 27 patients.

The precision of orthognathic surgery was evaluated in 27 patients. Rigid internal skeletal fixation was used without intermaxillary fixation. A computerized cephalometric program package (TIOPS) was utilized in the preoperative analysis, surgical planning, and postoperative examination. The mean positional difference of the cephalometric landmarks between planned and observed outcome ranged from -0.4 to 0.7 mm. Only one reference point (pm) differed statistically significantly from the plan (P = 0.02). All other mean differences in point location were of a magnitude that was not statistically different from zero (P > 0.05). It was concluded that no systematic sources of error could be demonstrated. However, the range of random variation in the individual cases left room for considerable improvement.