Assessment of facial soft-tissue profiles based on lateral photographs versus three-dimensional face scans

The purpose of this study was to compare two-dimensional (2D) lateral photographs versus three-dimensional (3D) face scans in analyzing facial profiles using Schwarz's concept of the jaw profile field (JPF) in its original 2D and in a modified 3D version. In addition, the distribution of the facial profile types described by Schwarz were examined.

Of 75 adult volunteers recruited specifically for this study, we obtained both photographs (Nikon D 300S; Nikon, Düsseldorf, Germany) and scans (FaceSCAN^3D Scientific Photolab 60 Hz; 3D-Shape, Erlangen, Germany) in a standardized setting. Four raters analyzed the pertinent measurements using image analysis software (Onyx Ceph 3; Image Instruments, Chemnitz, Germany). Statistical analysis was conducted using the R suite environment (v. 3.2.1; R Foundation for Statistical Computing, Vienna, Austria).

Intraobserver reliability was substantial for two raters (κ = 0.61-0.8), moderate for one (κ = 0.41-0.60), and almost perfect for one (κ = 0.81-1.00). As for interobserver reliability, we observed moderate agreement between the two basic technologies tested, but internal agreement was only moderate even within the 2D view modes (average κ = 0.51) versus almost perfect within the 3D view modes (κ = 0.84-0.94). Forward-slanting anteface was clearly the most common (43.27%) and straight retroface the least common (0.3%) diagnosis. Only a minority of patients (18.38% of women and 16.15% of men) had straight as opposed to slanting profiles.

Given our findings of acceptable agreement between 3D scanning and 2D lateral photography, in combination with almost perfect internal agreement between different 3D view modes, it appears useful to adapt Schwarz's method of facial profile assessment for clinical use in 3D virtual environments.