Alma Dozic

The aim of this study was to evaluate whether the VITA Classical shade guide arranged according to lightness allows clinicians to more often obtain a shade match than with an arrangement based on hue groups. A panel of 50 students determined the shade of the maxillary right central incisors of three patients with two differently arranged and blinded shade guides under standardized conditions. The L*a*b* values of the tabs were compared with those of the teeth spectrophotometrically. There were no statistically significant differences between the two arrangements. Using the arrangement according to lightness did not result in improved correct shade selection.

Porcelain veneers have become an interesting treatment option to correct the shape and color of anterior teeth. Because of their limited thickness and high translucency, achieving a good color match is influenced by several variables. The aim of this work was to investigate the influence of natural dentin and resin cement colors on final color match of porcelain veneers. A preselected shade tab (A1) was chosen as the target color for a maxillary central incisor, and its color parameters (L*a*b*) were measured using a digital spectrophotometer (SpectroShade, MHT). Nine natural dentin colors (Natural Die Material, Ivoclar Vivadent) representing a wide range of tooth colors were used to prepare resin replicas of the maxillary central incisor with a standard preparation for porcelain veneers. The prepared porcelain veneers (IPS Empress Esthetic, A1, 0.6 mm thick, Ivoclar Vivadent) were cemented on the resin dies (nine groups of natural dentin colors) using seven shades of resin cement (Variolink Veneers, Ivoclar Vivadent). The L*a*b* values of the cemented veneers were measured, and DE values were calculated against the preselected target color (A1). DE greater than 3.3 was considered as a significant color mismatch detectable by the human eye. The seven shades of resin cement had no significant influence on the final color of the veneers, as the measured DE values were almost identical for every test group. On the other hand, the color of natural dentin was a significant factor that influenced final color match. None of the 63 tested combinations (nine natural dentin colors and seven resin cement colors) produced an acceptable color match. Thin porcelain veneers cannot mask underlying tooth color even when different shades of resin cement are used. Incorporation of opaque porcelain (high chroma) may improve final color match.

Monochromatic ceramic blocks used for computer-generated posterior restorations require color modification to achieve acceptable shade matches. However, it is not known whether manipulative variables affect the final color of these restorations. This study aimed to determine the effects of ceramic type, thickness, extrinsic colorants, glazing, and luting agent on the final color of monochromatic computer-generated ceramics. One hundred forty-five ceramic specimens (12 mm x 10 mm) with different thicknesses were machined from monochromatic ProCAD ceramics (shades 100, 200, and 300; Ivoclar Vivadent) and Vita ceramics (shades A3.5 and 3M2; Vita). The influence of thickness on color was determined on ProCAD and Vita specimens with thicknesses of 1.0, 1.2, 1.5, 2.0, and 10.0 mm, and the influence of extrinsic colorants, glazing, and luting agent was determined on ProCAD and Vita ceramics of 1.5-mm thickness. Panavia F TC (Kuraray) was used to create a luting-agent backing of 100-microm thickness. CIELAB color coordinates (L*a*b*) were measured using a spectrophotometer, and color differences (DeltaE) between the specimens were calculated. The criterion for color difference was considered to be 1.5 DeltaE units. The data were statistically evaluated with ANOVA and the 2-tailed t test with a level of significance of 5%. All 5 variables demonstrated significant differences for both ProCAD and Vita ceramics (P = .000). The DeltaE values were larger than 1.5 units. Thickness and type of ceramic as well as extrinsic colorants, glazing, and a luting agent affect the color coordinates of monochromatic industrial ceramic.

Purpose: Visual tooth color assessment is neither accurate nor precise due to various subjective and objective factors. As newly developed tooth color‐measuring devices for dental application provide the possibility of a more objective means of color determination, their performances in vitro and in vivo must be evaluated. The objective of this study was to evaluate the accuracy and precision of five commercially available tooth color‐measuring devices in standardized and in clinical environments. Materials and Methods: In an in vitro study, standards (A1, A2, A3, A3.5, and A4 shade tabs of Vita Lumin) were measured five times with five electronic devices (ShadeScan, Easyshade, Ikam, IdentaColor II, and ShadeEye) by two operators. In an in vivo study, the right upper central incisors of 25 dental students were measured with the same electronic devices by a single operator. Vita shade tab codes were expressed as CIE (International Commission on Illumination) L*a*b* values and in terms of the precision and accuracy of ΔE color differences. The Mann‐Whitney statistical test was used to analyze the differences between the two operators in the in vitro study, and the Kruskal‐Wallis one‐way analysis of variance on ranks with the post‐hoc Tukey test was used to analyze the accuracy and precision of electronic devices. Results: No statistically significant difference was found between the different operators in the in vitro study. The obtained precision was Easyshade > ShadeScan ≅ Ikam > IdentaColor II > ShadeEye. The obtained accuracy was Easyshade > ShadeScan ≅ Ikam > ShadeEye > IdentaColor II. In the in vivo study, the Easyshade and the Ikam were the most precise, and the ShadeEye and the IdentaColor II were more precise than the ShadeScan. With respect to accuracy, there was no statistical difference between the ShadeScan, Ikam, and the Easyshade. The IdentaColor II was considered inaccurate (ΔE_a= 3.4). Conclusions: In the clinical setting, the Easyshade and Ikam systems were the most reliable. The other devices tested were more reliable in vitro than in vivo.