Objective evaluation of normal facial function.

The aim of this investigation was the assessment of normal facial movements using the objective computer-assisted OSCAR method. Computerized black-and-white video images of 20 healthy volunteers were recorded with the face at rest, maximal wrinkling of the forehead, forced eye closure, and forced smiling. The mean regional symmetry index was found to be 91% (SD 6%; range 80% to 99%) for wrinkling of the forehead, 93% (SD 5%; range 82% to 100%) for forced eye closure, and 91% (SD 5%; range 79% to 98%) for maximal smiling. Clinical weighting gave a global symmetry index of 92% (SD 3%; range 88% to 96%). The presented results show that the physiological dynamic asymmetry of the normal face is 7% to 9%. No dominant facial side could be found. The comparison of the results obtained with the OSCAR method with those of the subjective House-Brackmann and Fisch grading systems showed that the physiological asymmetry of facial movements can only be accurately determined with a computer-assisted objective method.