Correlation of Two Shade Guides for Evaluating tooth Bleaching Efficacy

Objective: Vitapan Classical Shade Guide (VC, Vita Zahnfabrik, Germany) has been used most commonly for evaluating tooth bleaching efficacy but it lacks linearity.  The newly developed Vita Bleachedguide 3D-Master (VBG, Vita Zahnfabrik, Germany) is linear with equal color intervals.  The purpose of the study was to investigate consistency and correlation of the VC and VBG for shade judgment among experienced dental clinicians.  Methods: Three dentists each with >10-year clinical experience performed visual shade-matching of the VC to VBG with a black background under color-corrected dental office lighting.  Each investigator conducted shade-matching procedures independently for three times, with an interval of at least one week between two evaluations, using the same shade guides, lighting conditions and environmental surroundings.  The data were analyzed for intra- and inter-examiner correlations as well as the correlation between the VC and VBG using the Pearson Correlation method.  Results: A significant correlation was detected within and between three investigators for the same shade guide (r >0.917).  There were variations in shade matching between the VC and VBG as well as among the three investigators.  While the VC correlated significantly with the VBG for all investigators and their averages (r >0.983), four VBG shades (0M1, 0.5M1, 1M1 and 5M3) did not match any of the 16 VC shades.  In addition, none the remaining 11 VBG shades matched only one VC shades, with some VBG shades matching multiple VC shades.  Variations also existed among three investigators in shade-matching between the VC and VBG shade guides.  Conclusions: The visual shade judgment is highly consistent and correlated for either the VC or VBG within and among three dentists.  While there is a correlation between the VC and VBG, variations exist even among experienced clinicians.