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

Abstract Objective To 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 Methods Digital 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 (Δ E 00 ) 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). Results Δ E 00 values of all test groups were higher than the clinically acceptable threshold (∆ E 00 > 1.80). While the ∆ E 00 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, ∆ E 00 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). Conclusion The 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 Significance The 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.