Pretreatment and posttreatment 3D facial images of static expression were fitted. (A) The colors in the different facial areas represent depth variation. The Frankfurt plane is the reference horizontal plane in Artec Studio (Artec 3D; Senningerberg, Luxembourg), and was adjusted to generate 3 horizontal planes where A, B, and C were located. The cross-sectional lines in the 3 planes are captured. (B) The 3D facial images before and after injection were superimposed, and the cross-sectional lines of each layer were extracted. (C) Two green lines indicate the contours of pretreatment and posttreatment models. The circle indicates the right area of the patient's NLF in vertical view. (D) The red circles represent the pretreatment curvature of a type M NLF while laughing in Rhino software. (E-H) The curvature change with time was analyzed by Rhino in both type M and type MF NLFs. The radius of the curvature is measured in millimeters. M, muscular type; MF, muscle–fat pad mixed type; NLF, nasiolabial fold.