Accuracy of analytic model planning in bimaxillary surgery.

The purpose of this study was to assess our method of analytic model planning in achieving a planned maxillary advancement for the correction of a dentofacial deformity. A consecutive series of 20 patients who underwent bimaxillary orthognathic surgery, at a minimum, were included in the study group. For each study subject, consistent analytic model planning with splint fabrication was used to establish the desired horizontal repositioning of the maxilla. Using preoperative and 5-week postoperative lateral cephalometric radiographs, an analysis was designed to assess the difference between the planned and actual advancement of the maxilla. The average difference between the planned and actual 5-week postsurgical advancement of the maxilla was 0.6 mm (range 0.2-1.0, P>0.05). There was a strong correlation between the two data sets (R=0.96). The results of the study indicate that the described method of analytic model planning is reliable (within 1mm) in achieving the planned level of maxillary advancement in bimaxillary orthognathic procedures.