Quantitative Assessment of Facial Asymmetry Using Three-Dimensional Surface Imaging in Adults: Validating the Precision and Repeatability of a Global Approach. D Kornreich, AA Mitchell, BD Webb, I Cristian, EW Jabs

Date: December 2014
Source: The Cleft Palate-Craniofacial Journal.

Article: Quantitative Assessment of Facial Asymmetry Using Three-Dimensional Surface Imaging in Adults: Validating the Precision and Repeatability of a Global Approach
Authors: David Kornreich, M.D., Adele A. Mitchell, Ph.D., Bryn D. Webb, M.D., Ingrid Cristian, M.D., Ethylin Wang Jabs, M.D.

Abstract
Objective
: Comparison of global versus landmark analyses of facial asymmetry using three-dimensional photogrammetry to establish a precise method for evaluating facial asymmetry.

Design: The landmark-based approach utilized anthropometric data points. Our global approach involved registration of mirror images, independent of a midplane, to calculate a root mean square (RMS) value. We analyzed precision and technical and operator error of both methods.

Participants: Three hundred fifty adults participated in this study.

Results: We found that the global method has better precision and repeatability with a significantly lower error rate than the landmark-based method. In adults, the average RMS was 0.6253 mm with a standard deviation of 0.16.

Conclusions: Our facial asymmetry measurement is more accurate than landmark-based measurements. This method is quick, reliable, and results in generation of a RMS score and a corresponding color-coded facial map that highlights regions of higher and lower asymmetry. This method may be used as a screening tool for asymmetry in both the clinical and research settings.