Intrarater repeatability of shade selection under two light sources with two shade guides

Color research has shown that shade guides do not always represent the color of natural tooth. Moreover, visual evaluation has been found to be unreliable and inconsistent. This study evaluated the effects of 2 shade guides and 2 light sources on the intrarater repeatability of prosthodontists, postgraduate students and laboratory technicians with regard to shade selection. Methods & Materials: Three prosthodontists, three postgraduate students and three laboratory technicians participate in this descriptive – analytic study. Examiners were tested to eliminate color blindness by Eshihara Test. Each clinician used Vita Classic and Vitapan 3 D- master shade guides under two light sources (sun light and corrected Dialite lamp) to determine the shades of the maxillary left canines of 20 patients following a standard protocol. The identification codes of the shade tabs were masked to prevent shade memory. All teeth were polished before each shade selection. Shade selection was randomly repeated 1 month later by the same practitioners on the same group of patients. Data were analyzed with two way analysis of variance (Anova). Significant interactions were found between the effects of shade guide system and specially training on intrarater repeatability (P<0.05). The intrarater repeatability of prosthodontists was significantly higher than that of postgraduate students and laboratory technicians when the Vita Classic shade guide was used (P<0.05). Use of the Vitapan 3 D – master shade guide significantly improved the intrarater repeatability of postgraduate students compared with Vita Classic shade guide (P<0.05). This improvement was not significant, however, among prosthodontists and laboratory technicians (P>0.05). Light sources didnt show any significant effects on intrarater repeatability of examiners. The prosthodontists demonstrated superior intrarater repeatability in shade selection, especially when the Vita Classic shade guide was used. Use of the Vitapan 3 D – master Shade guide notably improved intrarater repeatability among the postgraduate students.