Colour compatibility between teeth and dental shade guides in Quinquagenarians and Septuagenarians

Summary  The aim of this investigation was to determine colour compatibility between dental shade guides, namely, VITA Classical (VC) and VITA 3D-Master (3D), and human teeth in quinquagenarians and septuagenarians. Tooth colour, described in terms of L*a*b* values of the middle third of facial tooth surface of 1391 teeth, was measured using VITA Easyshade in 195 subjects (48% female). These were compared with the colours (L*a*b* values) of the shade tabs of VC and 3D. The mean coverage error and the percentage of tooth colours being within a given colour difference (ΔEab) from the tabs of VC and 3D were calculated. For comparison, hypothetical, optimized, population-specific shade guides were additionally calculated based on discrete optimization techniques for optimizing coverage. Mean coverage error was ΔEab = 3·51 for VC and ΔEab = 2·96 for 3D. Coverage of tooth colours by the tabs of VC and 3D within ΔEab = 2 was 23% and 24%, respectively, (ΔEab ≤ 2 as clinically acceptable match). The hypothetical guides performed better and would only need seven to eight tabs to reach the same results as VC and 3D. Both guides had a mean coverage error that was too high and coverage that was too low according to an acceptable colour difference of tooth colour for these subjects. The optimized hypothetical, population-specific guides performed better indicating the possibility for improvement in colour compatibility of the guides with tooth colour in future shade guide development, allowing acceptable shade matching for most of the patients in clinical routine.