Background: Reliable evaluation of the complex three-dimensional anatomy of the face has proven to be extremely difficult. Three-dimensional surface scanning technology has not yet reached widespread acceptance in clinical research in plastic surgery. This study aimed to describe two parameters that allow quantification of soft-tissue movements and to compare the surface changes of the lower face during positional changes and with increasing age.
Methods: Two groups, each with 20 voluntary female subjects aged 20 to 35 and 45 to 60 years, were examined with a three-dimensional surface scanner in both supine and sitting positions. After registration of the two surface scans, the soft-tissue mobility of the lower face was examined using two new parameters. Deformability describes the mean distance between the surfaces and stretchability describes the relative stretching of one surface when mapped onto the other.
Results: Both parameters show highly significant differences for tissue mobility of young versus old lower faces. The trend for the soft tissues to lose projection in the upper posterior aspect and gain projection in the lower anterior aspect increases strongly. In the older subjects, larger parts of the examined area show tissue displacements of up to 6 mm, whereas in the young faces the displacement is far less and does not exceed 4 mm.
Conclusion: Computational analysis of the authors' experimental results using two new parameters shows a statistically significant increase of facial tissue displacement and surface stretching when comparing young and old subjects.