Comparison between two-dimensional and midsagittal three-dimensional cephalometric measurements of dry human skulls.

The aim of this study was to compare two- and three-dimensional cephalometric values by using a three-dimensional analysis based on the midsagittal plane. Spherical metal markers were fixed on to the anatomical landmarks of 10 human skulls, which were examined radiographically with conventional lateral cephalograms and cone-beam computed tomographic (CBCT) scans. Preprogrammed analyses calculated the 18 angular and linear two- and three-dimensional cephalometric values. An error study was made to assess the accuracy and reliability of the methods used. Both sets of values were compared using Wilcoxon's signed-rank test. Probabilities of less than 0.05 were accepted as significant. Reliability of the measurements was assessed by intraclass correlation coefficients (ICC) based on absolute agreement. The method error (ME) was tiny (mean ME<0.61 measuring unit) and reliable (ICC>0.97). Comparison of the two- and three-dimensional measurements showed that that they were reliable (ICC>0.88) and that there were no significant differences (P=0.41-1.00). The values from the cephalometric analyses were comparable and interchangeable when using the midsagittal three-dimensional approach as described.