The accuracy of dental shade matching using cross-polarization photography.

The aim of this study was to assess the influence of a polarizing filter on the accuracy of dental shade matching using digital photography. A comparison was performed using ΔEab parameters between CIE L*a*b* values obtained from digital images taken under two different conditions (with direct light and with polarized light) and the values given by the dental spectrophotometer SpectroShade Micro, which is considered to be the standard. Color differences (ΔEab) calculated between the parameters recorded with the dental spectrophotometer and polarized photography were below or at the level of the 50:50% acceptability threshold of 2.7 in 23% of the cases. Interdevice agreement found between the dental spectrophotometer and polarized photography exceeded 0.82 for all the three parameters recorded. Digital photography with polarizing filters might be a useful tool for dental shade matching.