Effect of cross‐polarization filters on the trueness of colors obtained with a single‐lens reflex camera, macro lens, and a ring flash

Abstract

ObjectiveTo investigate the effect of cross‐polarization filters on the colors of shade tabs obtained with a digital single‐lens reflex (DSLR) camera, macrolens, and a ring flash.Materials and MethodsDigital images of four shade tables (1M1, 3L2.5, 3R2.5, and 5M3) from the VITA Toothguide 3D‐Master shade guide were taken using a DSLR camera, 100 mm macrolens, and ring flash with two different cross‐polarizing filters (Polar_eyes and Filtropolar), and without (Nonpolarizer; n = 7). The CIE L*a*b* color coordinates of digital images were calculated and remeasured with a spectroradiometer (SR). The color differences (ΔE00) between the SR and digital images were calculated and analyzed with the two‐way analysis of variance (ANOVA) and Tukey HSD test (α = 0.05).ResultsΔE00 values of all test groups were higher than the clinically acceptable threshold (∆E00 > 1.80). While the ∆E00 values of Filtropolar (6.19 ± 0.44) and Polar_eyes (7.82 ± 0.23) groups were significantly higher than the Nonpolarizer (4.69 ± 0.32) for the 1M1 shade tab, ∆E00 value of Polar_eyes (6.23 ± 0.34) was significantly lower than Nonpolarizer (10.71 ± 0.48) group for 5M3 shade tab (p < 0.05).ConclusionThe color‐matching results of tested digital photography techniques with and without cross‐polarization were unacceptable, compared to a spectroradiometer. While digital photography with Polar_eyes cross‐polarizing filter has closer results to the reference device for the low‐in‐value shade table (5M3), for the high‐in‐value shade table (1M1), improved results were obtained without a cross‐polarizing filter.Clinical SignificanceThe cross‐polarization filters are increasingly used in dentistry for tooth color communication with digital photography techniques. However, the digital photography techniques with‐without cross‐polarization filterers should be improved to obtain clinically acceptable color‐matching results.

The role of interface distance and underlying substrate on the color adjustment potential of single‐shade composites

“…Although the use of images is not a validated method for color measurements, previous studies have shown that standardizing image acquisition and correcting white balance using a neutral gray card can yield reliable results comparable to those obtained with spectrophotometers. [17][18][19] Another important consideration is the conversion of RGB values to CIELAB color coordinates, which depends on factors like the illuminant and observer angle. 20,24 The choice of an appropriate illuminant was a key parameter in our study, as we aimed to evaluate the color match of single-shade composites to the surrounding substrate.…”

“…It is crucial to ensure accurate color representation in the photographs to obtain reliable results, like those using devices specifically designed for color assessment (e.g., colorimeters). Although the use of images is not a validated method for color measurements, previous studies have shown that standardizing image acquisition and correcting white balance using a neutral gray card can yield reliable results comparable to those obtained with spectrophotometers 17–19 . Another important consideration is the conversion of RGB values to CIELAB color coordinates, which depends on factors like the illuminant and observer angle 20,24 …”

“…However, previous studies have used spectrophotometers that do not allow for the measurement of color in different areas of the specimen 9–12,16 . In contrast, digital methods based on imaging systems and software, such as DSLR cameras combined with a white balance gray card, allow for the measurement of the color of diverse and small areas of a specimen 17–19 …”

“…[9][10][11][12]16 In contrast, digital methods based on imaging systems and software, such as DSLR cameras combined with a white balance gray card, allow for the measurement of the color of diverse and small areas of a specimen. [17][18][19] Therefore, the present study aimed to evaluate the effect of the distance from the composite interface and an underlying chromatic substrate on the CAP of two single-shade composites. The hypothesis is that the CAP would increase closer to the composite interface and over a chromatic background.…”

Color discrepancy of single-shade composites at different distances from the interface measured using cell phone images

“…However, it is crucial to ensure that the colors in the images correctly represent the specimens for reliable results. To improve the reliability of the findings, using neutral gray references during image acquisition and ensuring proper illumination conditions is recommended [ 9 10 11 12 13 14 15 16 ]. Nevertheless, confirming the method’s accuracy is vital by comparing it to a validated technique, such as using a spectrophotometer [ 14 17 ].…”