Updated: Jun 5, 2026

Longitudinal Intravital Imaging Through Clear Silicone Windows
Published on: January 5, 2022
Xingxue Hu1, William M Johnston
1The Ohio State University College of Dentistry, 305 W. 12th Ave, Columbus, OH 43210, USA.
This study aimed to find reliable ways to measure how translucent thick, pigmented materials are, especially those used in prosthetics that mimic human skin. Two optical methods—LLDA and CDEL—were tested on 19 different skin-colored silicone samples. The study found that both methods gave accurate results and could be used to estimate translucency without damaging the material. The LLDA method, in particular, showed promise as a non-contact technique. These findings suggest that these methods could help improve the visual realism of prosthetic devices by better matching the translucency of human skin.
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Area of Science:
Background:
Human skin exhibits a complex, layered structure with partial translucency, making it difficult to quantify translucency in a way that matches standard material testing. Prior research has shown that traditional methods for translucent materials do not easily apply to skin or skin-like materials. This gap motivated the need for a new approach to estimate translucency in thick, pigmented materials. Existing methods often fail to account for the optical properties of pigmented layers. No prior work had resolved how to measure translucency in thick prosthetic materials accurately. This uncertainty drove the development of a new optical technique. The challenge lies in translating skin-like translucency into measurable parameters. Researchers have proposed using optical methods to approximate translucency in skin-colored prosthetics. The goal is to improve the visual realism of prosthetic materials.
Purpose Of The Study:
The aim of this study was to develop and compare two optical methods for estimating translucency in thick, pigmented maxillofacial elastomers. The specific problem addressed is the lack of a reliable, non-contact method for quantifying translucency in materials that mimic human skin. The motivation stems from the need to improve the appearance of prosthetic devices. Translucency is a key factor in achieving realistic skin color and texture. The study focused on skin-colored elastomers used in maxillofacial prosthetics. The researchers proposed using laser light diffusion and color difference measurements. These methods were tested on a range of pigmented materials. The study sought to determine which method provides the most accurate translucency estimation.
Both LLDA and CDEL methods provided accurate translucency estimates with adjusted R² ≥ 0.919.
Nineteen skin-colored silicone samples were made using tan, red, yellow, and black commercial pigments.
The researchers propose that LLDA is non-contact and suitable for thick, pigmented materials.
CIELAB and CIE2000 formulas were used to calculate translucency parameters at 1.5mm thickness.
Main Methods:
The study used two optical techniques—laser light diffusing area (LLDA) and color difference due to edge loss (CDEL)—to estimate translucency in maxillofacial elastomers. Specimens were made from 19 different skin-colored shades of silicone elastomer. Each sample was pigmented with tan, red, yellow, or black commercial pigments. Translucency parameter (TP) values were calculated using the CIELAB and CIE2000 color difference formulas. The TP values were based on measurements at 1.5mm thickness on black and white backings. Regression models were developed to predict TP from LLDA and CDEL measurements. The accuracy of both methods was compared using adjusted R² values. The study evaluated error variances to assess the reliability of each method.
Main Results:
Both LLDA and CDEL methods provided accurate translucency estimates with adjusted R² values of 0.919 or higher. The error variances between the two methods were not significantly different. The LLDA method showed a strong correlation with TP values across all 19 material shades. The CDEL method also demonstrated high predictive accuracy for translucency. The regression models for both methods were reliable within the tested range. The study found no significant difference in the performance of the two techniques. The LLDA method may be particularly useful for non-contact translucency estimation. The results suggest that both methods can be applied to thick, pigmented materials.
Conclusions:
The researchers propose that the laser light diffusing method is highly reliable for estimating translucency in maxillofacial elastomers. The LLDA method may be used to estimate the apparent translucency of thick materials. The study suggests that both LLDA and CDEL methods can be applied to prosthetic materials. The findings indicate that these optical methods are suitable for non-contact, non-destructive testing. The authors propose that the LLDA method could be incorporated into appearance matching of prosthetics. The study supports the use of LLDA for translucency estimation in skin-colored materials. The results suggest that these methods may be applied to human skin in future research. The study concludes that LLDA is a promising technique for translucency measurement.
Adjusted R² ≥ 0.919 indicates strong predictive accuracy of LLDA and CDEL methods.
The authors propose that LLDA may be used to estimate translucency in human skin and prosthetics.