Classifying the Natural Tooth Color Spaces of Different Ethnic Groups

Abstract

This study aimed to classify the natural tooth color spaces of various ethnic groups and assess the coverage error (CE) of the Vita 3D-Master shade guide. A sample of 490 volunteers from five ethnic backgrounds participated, with inclusion criteria set for adults aged 20– to 45 with healthy, correctly aligned natural teeth free of restorations. Teeth showing caries, restorations, or substantial staining were excluded. Tooth color was measured through a standardized photographic method, employing a gray reference card and cross-polarized filters. Color differences were computed using the CIEDE2000 formula, and CE was determined. Examiner reliability was verified, and data were analyzed in R software, with significance set at p < 0.05. The results indicated significant disparities in tooth color parameters among ethnic groups. Lightness levels varied significantly, with African teeth presenting the highest values and Caucasians the lowest. While redness and yellowness values overlapped among some groups, African, Middle Eastern, and South Asian teeth showed higher redness, whereas East Asian and South Asian teeth were more yellowish. The mean CE of the Vita 3D-Master shade guide was 5.1 ∆E ₀₀ across all ethnicities, exceeding the acceptable threshold (AT ≤ 1.8). The Southeastern group had the lowest CE at 2.8 ∆E ₀₀, while the African group had the highest at 6.3 ∆E ₀₀. These findings reveal that the color gamut of natural teeth extends beyond the coverage of existing shade guides, with notable variations across ethnicities. This underscores the necessity for enhanced shade guides to achieve reliable color matching in clinical settings.