A comparative study of linear measurements of facial skeleton using computed tomography and traditional cephalometry

Background: Radiographic imaging is an important adjunct in the assessment of skeletal and dental relationships for the orthodontic patient. Imaging is one of the most ubiquitous tools used by orthodontists to measure and record the size and form of craniofacial structures. Materials and Methods: The objectives of the study were to compare the measurements from human skulls and their images from cephalometric radiographs and computed tomography (CT) scanograms in order to gauge the potential use of CT in routine clinical practice. Based on the specific criteria including stable occlusion and condyles fitting stably in glenoid fossa, 15 dry human skulls were selected. Lateral, posteroanterior cephalograms, and CT scout views were taken of each skull by standardized methods. Linear measurements were made on all three records. Intraclass correlation coefficients, Pearson's correlation coefficient and regression constant were calculated to assess the records. Results: The linear measurements of the cephalometric record are greater than CT measurements on scout images. In vertical plane, the CT projections are more coinciding with the direct skull measurements. In sagittal and transverse planes, the cephalometric measurements were more correlating with the direct skull measurements. Conclusions: The cephalograms and CT scanograms differed in accuracy of linear measurements, because of variation in the location and size of an object, within the imaged 3D structure of both records.