Three-dimensional analysis of facial asymmetry using two-dimensional cephalometric radiographs

Objectives: Three-dimensional (3D) CT image has a limitation in use due to high cost while it provides an accurate information for the diagnosis of facial asymmetry. The purpose of the present study was to evaluate the possibility of the 3D analysis of the facial asymmetry using 3 cuts of 2-dimensional (2D) cephalometric radiographs. Methods: Three cephalometric radiographs of the frontal, lateral and submento-vertex projections were taken and maxillofacial 3D images were constructed with CT in 30 individuals with facial asymmetry. The degree of the menton deviation was measured from the frontal cephalometric film. Six pairs of measurements (maxillary height, ramus length, frontal ramal inclination, lateral ramal inclination, body length and body height) were established, as the measurements related with menton deviation, on the 2D radiographs and 3D CT images, respectively. The differences between 2D and 3D measurements were compared and correlation analysis with the degree of menton deviation were performed. Results: The differences between 2D and 3D results showed small values, within approximately 1° or 1 mm. The comparison between 2D and 3D results showed no statistically significant differences in all measurements used in this study. As the results of correlation analysis between menton deviation and the difference between 2D and 3D results, all measurements showed no statistically significant correlations. Conclusions: The results of the present study suggest that 3D analysis of facial asymmetry is possible with 2D cephalometric radiographs if the measurements described above are used in frontal, lateral and submento-vertex views of cephalometric radiographs.