Coverage error of gingival shade guide systems in measuring color of attached anterior gingiva

Statement of problem: It remains unclear which gingival shade guide is most effective in producing the best visual shade match. Purpose: The purpose of this study was to determine and compare the coverage errors (CEs) of 2 different gingival shade guides and their combination in a selected population. Material and methods: The CEs of the following gingival shade guides were evaluated: (1) Lucitone 199, (2) IPS Gingiva, and (3) a combination of the 2 shade guide systems. The spectral reflectance values of the center of each gingival shade tab (1.5 mm in diameter) were measured (without a backing) with a spectroradiometer and an external light source at wavelengths from 380 nm to 780 nm at 2-nm intervals. All spectral reflectance measurements were made using 0-degree observer and 45-degree illumination and then converted to CIE values. The attached gingiva of 120 subjects was measured with the same protocol. The CEs of each of the 120 subjects' attached gingiva for each of the 2 shade guide systems and their combination were determined and averaged. The mean minimum CEs were analyzed with repeated measures ANOVA and the post hoc Tukey HSD for multiple comparison (α=.05). Results: A significant difference (P<.001) was found among the mean minimum CEs of the 2 gingival shade guide systems and their combination. The Tukey HSD test revealed that the mean minimum CEs for Lucitone 199 (ΔE 10.8 ±4.4) were significantly different from the IPS Gingiva (ΔE 8.6 ±3.6) shade guide system. However, the combination of the 2 gingival shade guide systems (ΔE 7.9 ±3.4) was not significantly different from the IPS Gingiva system, but a significant difference was found among races (P=.016). No interactions were found between the other tested groups. The mean CE for white individuals (ΔE 8.3 ±2.5) is significantly different and less than the mean CE for African Americans (ΔE 10.0 ±4.4). The CEs for Asians (ΔE=9.1 ±4.3) and others (ΔE 9.0 ±4.4) are not significantly different from CEs for whites or African Americans. Conclusions: The IPS Gingiva shade guide system resulted in the lowest CEs compared to the Lucitone 199 shade guide system. The mean CE for Lucitone 199 was significantly greater than the mean CE for IPS Gingiva and for the combination of the 2 guides. The mean CE for whites is significantly different and less than the mean CE for African Americans. The CEs for Asians and others are not significantly different from CEs for whites or African Americans. (J Prosthet Dent 2009;101:46-53).