Comparison of three-dimensional facial morphologies acquired with digital stereophotogrammetry imaging system and computed tomography

Abstract Objective The aim of this study was to compare the characteristics of 3D facial images obtained by multi-detector computed tomography (MDCT) and stereophotogrammetry and to determine whether both methods can be integrated with accurate analysis in the same coordinate system for treatment planning and postoperative assessment in orthognathic surgery. Methods The subjects were 20 patients with jaw deformities. All of the patients underwent MDCT and stereophotogrammetry examinations for the assessment of maxillofacial morphologies before treatment. Standard triangulated language (STL) data of 3D facial surface images obtained by using MDCT and stereophotogrammetry were superimposed with four landmarks and the forehead and nasion area by a best-fit algorithm. The differences in Z coordinate values (mm) at ten measurement points and in six measurment volumes (cm3) between images obtained by using MDCT and stereophotogrammetry were calculated. Differences in Z coordinate values at the central measurement points were within 1 mm, but differences at the lateral measurement points, especially lower points, were significantly large. The volumes using MDCT were smaller than those using stereophotogrammetry, especially at lateral regions. Mean differences at the central measurement volumes were within 1 cm3, but mean differences at the lateral measurement volumes, ranging from 1.6 cm3 to 3.5 cm3, were comparatively large. In conclusion, the method presented for 3D superposition of images obtained from different modalities may be useful for treatment planning and postoperative evaluation of orthognathic surgery.