A novel method for measuring and monitoring monobloc distraction osteogenesis using three-dimensional computed tomography rendered images with the 'biporion-dorsum sellae' plane. Part I: Precision and reproducibility

The results of craniofacial and orthognathic surgery have traditionally been monitored using lateral cephalometry. In the age of computed tomography (CT) and magnetic resonance imaging (MRI), newer methods of measuring surgical outcome have arisen. This has been further enhanced by the use of computer software to render CT images in a three-dimensional format. The authors present a novel method of measuring the outcome of monobloc distraction osteogenesis advancement using the biporion-dorsum sellae plane. The perpendicular distance of eight facial skeletal points to this plane were made automatically using the Vworks 4.0 program. A total of 10 measurements were made against six planes of reference. Planes 1, 2, 3, 1+2 degrees, and 1-2 degrees were constructed, and measurements were made by observer 1. Plane 6 was constructed and measurements were made by observer 2. Plane 1 was used as the denominator on which calculations were made. The results revealed a mean intra- and interobserver percentage difference from plane 1 of less than 5%. In addition, the overall mean intraobserver variance of all eight points from observer 1 was 0.91%, and the mean interobserver variance between observer 1 and 2 was 0.73%. In summary, based on the authors' method, repeated measurements made from the biporion-dorsum sellae plane have proven precision and reproducibility.