[Advances in determination of median sagittal plane of facial soft tissue].

Facial symmetry is a crucial component of human facial esthetics. Along with the increasing pursuit of aesthetic, in recent years, more and more researchers have focused on facial asymmetry assessment, of which determining the facial median sagittal plane is the first and most important step, and it will directly affect the accuracy of asymmetry evaluation and clinical treatment outcome. Limited by technical means, the earlier studies of facial soft tissue asymmetry assessment were mainly based on midline from two-dimensional (2D) images. Along with the development of three-dimensional (3D) measurement and data analysis techniques, new methods such as 3D landmark-based method and mirror-original alignment method have become main trend nowadays. This article systematically reviews the methods of determination of median sagittal plane of facial soft tissue, elaborates the developments and the latest research progress in this field, and discusses the advantages and limitations of each method in order to provide reference for clinical application.