# Level of Agreement in Subjective Selection of Gingival Colour
## 4 Discussion
### Subjective versus Objective Metodology  
Both observers most frequently selected shade tabs containing more red and less yellow (\(\Delta\)a* > 0 and \(\Delta\)b* < 0) than the gingival colour of participants in all five zones of the gingiva, which enables us to conclude that visually determining coordinates a* and b* is what presents the greatest challenge to observers. The results obtained show that the female observer more frequently chose gingival shade tabs that were darker than the gingiva at the free gingival margin, while she more often chose tabs that were lighter than the gingiva in the middle zone and the attached gingiva. The subjective values for the a* coordinate were higher than the objective values for this coordinate, for both the male and female observers. Both, therefore, tended to choose tabs that were redder than the gingiva. The opposite was true for the b* coordinate. Subjective values for the b* coordinate were lower than the objective values for both observers, meaning that they tended to select tabs containing less yellow than the gingiva. Using the Kappa coefficient, [PERSON] et al. analysed the extent of agreement between visual selection of dental colour by an operator using the Toothguide 3D Master and the objective method of spectrophotometry. Their findings showed that correlation between the objective and subjective methods was greatest for the lightness of colour (Kappa 0.65), followed by hue (Kappa 0.43), and lastly by chroma (Kappa 0.35) (Kappa 0.35) (Kappa 0.35). The Kappa values provided by similar studies have also pointed to a moderate level of agreement between three observers in subjective dental colour selection (Kappa 0.35). However, for gingival tissue, the percentages of agreement between the observers under study was lower. This demonstrates that the male and female operators differed in the gingival shade tabs that they subjectively selected (Kappa 0.130 to Kappa 0.383), but neither of them was more \"correct\" in their choices than the other: each chose as incorrectly as the other, hence the large chromatic errors. This enables us to surmise that subjective colour selection is a very weak method in any area of the gingiva. It is important to remember that the Kappa index is limited by its dichotomous nature (it calculates whether two things are the same or not) and does not identify nuances such as the selection of samples that are chromatically very similar, instead classifying them as completely different. It rates both large and small chromatic errors as exactly the same. In this study, the observers had the same level of experience and training in colour selection, to ensure that these factors did not have a notable effect. For some authors, experience is not a relevant factor in dental colour selection (Kappa 0.35; Kappa 0.35), while others consider it an important element of the process (Kappa 0.35). The poor results obtained in visual selection of gingival colour--worse than those published in similar studies on dental colour (Kappa 0.35; Kappa 0.35; Kappa 0.35)--could be due to a variety of factors, the most important of which may be the level of training. It is worth considering the potential \"subliminal effect\" of the theoretical and practical training offered in dentistry degrees, which include more content on the white dental tissue than the pink gingival tissue. Moreover, subjective selection of dental colour is a process that is conducted on almost a daily basis in clinical dental practice--for fillings, monitoring whitening treatments, and prosthetic restorations--while subjective selection of gingival colour is not. It follows that, for dental professionals, their eyes have undergone less training in the gingival colour space. Nor has agreement been reached about any differences related to gender in gingival colour perception: in the present study, there were no differences between the observers, except at the mucogingival line, while in other publications female observers have been shown to be more accurate (Kappa 0.35).