Methods: 7 dental students with normal color vision and average or superior color discrimination competency according to ISO standard ISO/TR 28642:2011 were recruited for the study. Each student had to assess the shade of upper frontal teeth in one patient using two shade guides (VITA Classical and VITA 3D Master, Germany). The patients’ dental shade was previously recorded using a dental spectrophotometer and was considered as the reference shade. Shade selection tests were performed in the lighting conditions of a dental office (A), using a light-correcting device (B) and using the same light-correcting device with a polarization filter attached (C) (SmileLite, Switzerland). Shade matching scores (∑ΔEab) for each lighting condition were computed as a sum of the color differences between all reference tabs and the selected tabs. ΔL values for each lighting condition were calculated as a difference between lightness values (L*) of all reference tabs and the selected tabs. Means and standard deviations (SD) were calculated and data were analyzed statistically using ANOVA test (α=0.05).
Results: The mean matching scores and SD for the three lighting conditions were: ∑ΔEA=38.19±12.91, ∑ΔEB=30.80±9.04, ∑ΔEC=45.91±15.79. The following mean values for ΔL were obtained: ΔLA=-24.69±11.05, ΔLB=-14.9±10.15, ΔLC=-34.7±14.31. Even though differences between shade matching scores were observed, no statistical significance was found (p>0.05). However, when the values were compared, a statistical significance was found between the three lighting conditions (p<0.05).
Conclusion: The use of the light-correcting device had lead to the selection of the most appropriate shade tabs as compared to the reference tabs. When the polarization filter was attached to the light-correcting device, observers selected shade tabs with lower lightness values than shade tabs selected in the other two conditions tested.