Determination of VITA Classical shades with the 3D-Master shade guide

Objectives. Because of its good matching performance the VITA 3D-Master shade guide (3D) is frequently used for determination of tooth color. Numerous composites/ceramics are, however, available in VITA Classical (VC) shades only. The objective of this study was to investigate the possibility of performing a shade match with 3D Master and converting this result via a table in a VC shade (indirect method) without this resulting in an apparent inferior shade matching in comparison with direct shade matching with the VC. Methods. Experiments were performed with an artificial, computer-generated tooth color space. Conversion tables were generated by calculating the color difference (DE) between a 3D shade and the closest VC shade (simple conversion table) and with the aid of optimization procedures. Statistical differences between the direct and indirect methods and between the indirect methods were assessed by use of a U-test. Results. Median DE was 2.38 for direct matching with the VC and 2.86 for indirect matching by use of a simple conversion table (p < 0.01). Optimized tables performed slightly better (median Delta E = 2.81). Conclusions. Within the limitations of the study, it is usually possible to determine tooth color with the 3D and convert it, via a table, into a VC shade without adding a clinically apparent error to the direct shade match with the VC.