Analysis of translucency of skin by volume reflection for color formulation of facial prostheses

Purpose: A facial prosthesis demands a good visual match with the adjacent skin. Skin color and translucency must be mimicked by the prosthesis. Translucency can be defined as allowing the passage of light, yet diffusing it so as not to render the bodies beyond clearly visible, therefore being semi-transparent. The translucency of skin hampers color measurements of color meters recommended by the Commission Internationale de l'Eclairage (CIE) due to edge loss. The aim of this study was to analyze the translucency of skin at different body sites by measuring volume reflection in a cohort of Caucasian individuals. Materials and Methods: To analyze skin translucency, a volume reflection meter (VRM) was applied to the skin of the forehead, cheek, palm of the hand, and lower forearm. The VRM measures the volume reflection of a small incident light beam at three different distances from the incident beam. To describe the impact of translucency on skin color and the impact of volume reflection at different distances of an incident beam, the VRM spectra were converted into CIE L*a*b* coordinates. Results: VRM measurements were carried out on a cohort of 48 individuals during spring. The mean age was 40.8 years (+/- 11.7 years). Statistically significant interactions between body site, distance from the light source, and L*, a*, and b* values were found. L* values decreased and a* and b* values increased at longer distances from the incident light beam since the light path was increased. Conclusion: Skin on the forehead, cheek, palm of the hand, and lower forearm each have their own specific volume reflection and thus, translucency, absorption, and scattering characteristics. These location-specific characteristics are due to known local differences in the skin's multilayered structure. For a good visual match between a facial prosthesis and the adjacent skin, volume reflection measurements of the skin close to the intended site of the prosthesis are necessary. Int J Prosthodont 2009; 22: 623-629.