Quantitative analysis of facial movement--a review of three-dimensional imaging techniques.

Objective analysis of facial movement forms an important consideration in the assessment and outcome of several medical disciplines. Technological advances in the field of medical imaging have meant techniques to measure facial movement have evolved from subjective grading scales to facial-marker-based tracking systems to the most recent development of true three-dimensional marker-free systems. The aim of this paper is to provide a comprehensive review of the literature in this evolving field of medical imaging particularly focusing on three-dimensional analysis of facial movement and outlining the current concepts in objective analysis of the data set.