RESUMO
PURPOSE: Color matching a facial prosthesis to human skin is very challenging. Colorimeters aid this process by adding objectivity to what is an otherwise subjective procedure. Mobile phone colorimeter applications offer a less expensive and widely available alternative to dedicated colorimeter devices for color measurement. There is a lack of evidence in the literature regarding the suitability of mobile phone colorimeter applications for the development of silicone shades for facial prosthetics. The purpose of this study is to determine the suitability of a mobile phone colorimeter application for matching natural skin colors during the fabrication of maxillofacial prostheses. MATERIALS AND METHODS: Ten pigmented maxillofacial silicone elastomer swatches were fabricated to mimic a range of human skin tones. Color measurements of these swatches were recorded using a test instrument-the mobile phone colorimeter application (RGB Colorimeter) and a reference instrument-the commercially available skin color measurement device e-skin spectrocolorimeter. Comparisons in trueness and precision of the color measurements were made using previously described methods. Data analysis was performed on the recorded results for each of the parameters at three distances (25, 30, and 35 mm) of the test instrument from the target against both a black and a white background. RESULTS: The trueness of the mobile phone colorimeter application relative to the colorimeter device varied depending on the distance from the target and the background color. The relative trueness of the color difference measurements fell just within the documented upper threshold of acceptable limits of color difference (∆E 3.0 - 4.4). The calculated precision of the CIE L*a*b* and ∆E measurements of the mobile phone colorimeter application was good, with the latter being well within the documented acceptable limits. CONCLUSIONS: A mobile phone colorimeter application would be a suitable aid in objectifying the process of color matching a silicone maxillofacial prosthesis. Further investigation into image calibration to improve trueness and the control of variables such as background noise, uniformity of illumination, and measuring distance is required.