Faces in 4 dimensions: Why do we care, and why the fourth dimension?

Abstract

The purpose of this article is to describe a dynamic approach for 3-dimensional analyses of facial soft-tissue movements. The method and analysis have numerous applications but, most specifically, are used to assess diagnostic and treatment outcomes of soft-tissue surgery in patients with repaired cleft lip and palate.

Copyright © 2011 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Figures

Fig 1

Child with cleft lip and palate: A, at birth; B, after lip repair; C, age 7 years.

Fig 2

Motion analysis system: A, data acquisition (reprinted from Trotman et al. Functional outcomes of cleft lip surgery. Part II: Quantification of nasolabial movement. Cleft Palate Craniofac J 2007;44:607-16. With permission from Allen Press Publishing Services); B, the system recognizes and tracks landmarks secured to the face.

Fig 3

The unit of measurement is the “interlandmark” distance. Consider any 2 landmarks on the face (left upper lip circle in the left schematic). When the patient smiles, this distance increases (first vertical line on graph), then the distance is held (horizontal portion of line on graph), and finally the distance decreases as the patient relaxes (second vertical line on graph).

Fig 4

Patient with a repaired left unilateral cleft lip. Animation of statistical modeling (available online) shows the mean movement of facial landmarks for this patient (solid red circles) compared with the mean movement of 37 noncleft subjects (open black circles) during a smile animation.

Fig 5

Patient with a repaired bilateral cleft lip. Animation of smile movement modeling (available online) shows that, compared with the mean noncleft smile movement (open black circles), the patient has limited contraction in the upper lip and limited overall movement of the upper lip region (solid red circles).

Fig 6

Three-dimensional images obtained from the 3dMD Motion Capture System.