# Level of Agreement in Subjective Selection of Gingival Colour
## 3 Results
Figure 4b-f illustrate the differences between the a* coordinate and the b* coordinate of the shade tab selected and the gingiva, for each gingival zone. A data point located in the first quadrant (\(\Delta\)a* > 0 and \(\Delta\)b* > 0) shows that the tab selected contains more red (less green) and more yellow (less blue) than the gingiva; a data point located in the second quadrant (\(\Delta\)a* > 0 and \(\Delta\)b* < 0) shows that the tab selected contains more red (less green) and less yellow (more blue) than the gingiva; a data point located in the third quadrant (\(\Delta\)a* < 0 and \(\Delta\)b* < 0) shows that the tab selected contains less red (more green) and less yellow (more blue) than the gingiva; finally, a data point located in the fourth quadrant (\(\Delta\)a* < 0 and \(\Delta\)b* > 0) shows that the tab selected contains less red (more green) and more yellow (less blue) than the gingiva. As these figures show, in all zones, there is a larger number of data points in the second quadrant than in the others, indicating that most of the shade tabs selected by the male observer contained more red and less yellow than the participants' objective colour coordinates. There is no significant difference between the five gingival zones when it comes to the proportion of data points in each quadrant (\(\chi^{2}\) = 12.728, \(p\) = 0.389). Table 4 shows the means and standard deviations of the colour differences--calculated using the Euclidean formula (\(\Delta\)Eab*) and the CIEDE2000 formula (\(\Delta\)E00)--between the colour coordinates of the shade tab chosen by the female observer and the patient's objective colour coordinates. With 101 participants and five gingival zones, a total of 505 colour readings were taken. Figure 4: Direction and extent of CIELAB colour coordinates (male observer). (**a**) \(\Delta\)L* distribution; (**b**–**f**) \(\Delta\)a* - \(\Delta\)b* in the mesial papilla, distal papilla, free gingival margin, middle zone, and mucogingival line, respectively. There were no statistically significant differences between the mean values of the colour differences, in the five gingival zones (CIELAB: F = 2.004, \(p\) = 0.093; CIEDE2000: F = 2.374; \(p\) = 0.051). Table 5 shows the means and standard deviations of the differences between the colour coordinates of the shade tab chosen by the female observer and the objective colour coordinates of the patients' gingiva. There were statistically significant differences between the three coordinates in the five gingival areas. In all of these areas, the a* coordinate had the lowest level of \"fit\" between the subjective and objective readings, in contrast with the L* coordinate, for which the fit was best in all the areas, except at the mucogingival line. When comparing these results for divergence from the objective colour coordinates for the man and the woman, no statistically significant differences were found in any gingival area, except the middle zone, in which there was a statistically significant difference between \(\Delta\)L* (\(-2.37\) vs. 1.02, \(p\) = 0.014) and \(\Delta\)a* (6.26 vs. 4.11, \(p\) = 0.025) for the male and the female observer. Figure 5 shows the differences in each colour coordinate for the 101 patients for whom the female observer selected the shade tab she considered closest to their gingival colour, by gingival zone.