Does facial asymmetry vary between subjects of different age groups? A 3D stereophotogrammetry analysis.

This study was aimed to assess whether facial asymmetry increases with age and to examine potential gender differences using 3D stereophotogrammetry. A prospective cross-sectional study was performed. 3D photographs were acquired from 600 control subjects, 300 male, 300 female, and were stratified into 15 different age groups ranging from 0 to 70+. The 3D photographs were postprocessed and mirrored. The original and mirrored faces were surface-based matched using an iterative closest point algorithm. The primary outcome variable, facial asymmetry, was evaluated by calculating the absolute mean distance between the original and mirrored images. The primary predictor was age. Pearson's correlation was used to assess the correlation between facial asymmetry and age. The average overall facial asymmetry was 0.72 mm (SD 0.72 mm; range 0.25 - 3.04 mm). Mean facial asymmetry increased significantly with age, from 0.45 mm in the age group of 0-4 years to 0.98 mm in the age group of 70+ (p<0.001). Facial asymmetry was positively correlated with age (Pearson's r = 0.55; p<0.001). Male subjects were significantly more asymmetric compared to females, 0.77 mm and 0.67 mm, respectively (p<0.001). This study indicates that facial asymmetry significantly increases with age and is significantly larger in males than in females.

Three dimensional evaluation of facial asymmetry after mandibular reconstruction: validation of a new method using stereophotogrammetry.

The scientific literature is sparse on reports that evaluate facial asymmetry after mandibular reconstructive surgery objectively. The aim of this study is to introduce and validate a new method, using three dimensional (3D) stereophotogrammetry, that quantifies soft-tissue facial asymmetry in patients who have undergone mandibular reconstruction. To validate the new method, two observers applied the method on 3D photographs of five patients and five controls. An inter-observer difference of 0.04 mm (-0.08 to 0.17) was found with a measurement error of 0.13 mm. 15 3D photographs of the mandibular reconstructed patients were compared with 24 3D photographs of healthy controls. A significant difference (1.19 mm) in asymmetry was found between patients and controls. It is concluded that this new measuring method is a valid, fast and clinically applicable technique to quantify soft-tissue facial asymmetry. It is concluded that facial symmetry in patients is not restored to the level of the control group with the mandibular reconstruction method applied.