||Estimation in skin smoothness is of everincreasing interest especially in the field of cosmetic research. There is a growing demand for sensitive reproducible methods for measuring features of photoaging such as wrinkles and dermal structural changes.
In the beginning the technique was used merely to describe features on the surface of the skin or a skin replica that could be observed in a microscope.
More quantitative studies of skin structure started about 40 years ago, and have included both two-dimensional and, more recently, three-dimensional studies. These methods can be subdivided into two categories:
1. Structure mapping based on analysis of an image of the surface. These systems include image analysis of videoscans, and the fully automated system in which the shadows cast by incident light on a replica may use to determine primary and secondary direction and depth of furrows and also determine skin surface area.
2. Topographical mapping of the structure based on scanning of surface height (two- or three dimensional scanning). This category includes profilometers-mechanical or optical.
Normally skin replicas, impressions that are used as reproductions of skin relief, are used as study objects in profilometric studies.
Various methods for analyse skin have been developed using skin replicas of silicone material. As sample generation is simple, precise and not affecting skin function and structure, repeated investigations of the same area are possible. Changes in skin surface can be registered in their temporal course, to analyse qualitative and quantitative differences of skin diseases and to investigate dynamically time-dose relations of topical or systemic treatments.
Optical and stylus profilometry can be used for the quantification of facial wrinkles as a result of sun exposure, age and smoking history and the effect of their topical treatment.