Abstract: Objective：To compare two digital methods of quantitatively accessing the degree of facial asymmetry by three-dimensional data. Methods: The three-dimensional data of 20 subjects were got by the FaceScan, and then were input to the reverse engineering software Imageware 13.0 and Geomagic 12. Their mirror data were acquired and superimposed with the original data by the methods of interactive closest points (ICP) and Procrustes analysis (PA). The mid-sagittal planes of the two methods were extracted respectively, the degree of facial asymmetry and the distance of 21 automatic landmarks to midsagittal plane were calculated and compared. Results: The paired t test was taken and t=1.346, P=0.193. Conclusion: We can safely come to the conclusions that for the subjects with no evident facial asymmetry, there are no significant difference between the PA and the ICP methods for extracting the mid-sagittal plane from three-dimensional data.

Key words: Facial asymmetry, Imaging, three-dimensional, Interactive closest point, Procrustes analysis