“Instrumental and Visual Color Assessment of Single and Reduced-Shade Composites”

Objectives: Evaluate shade match of four composite resins to bilayered acrylic teeth using spectrophotometer measurements and visual assessment.
Methods: Bilayered denture teeth representing 5 Vita shades (B1, B2, A2, C2, D3) were selected. The materials included Filtek Supreme, 3M Universal, Omnichroma, and an Experimental resin. Each tooth was prepared to a dimension of 5mm in width and 2mm depth on the occlusal surface (n=100). One operator placed the composites in two increments curing each at 1250mW/cm2. Each shade had five restorations placed for each material. The flat occlusal surface was polished using a 2 step-system at 6,000rpm. Three color readings were made for each specimen, before preparation and after restoration with the Vita Easyshade and averaged. Difference in color was calculated as ΔE_00. One restoration of each shade and material group was rank ordered by 12 experienced clinicians.
Results: Two-way ANOVA revealed significant difference between materials and shades (P<0.001). ΔE₀₀ values were compared with four materials within each of 5 shades using multi-comparison tests One-Way Anova and Tukey. For all shades there is no significant difference between Supreme, Universal and the Experimental group but Omnichroma was significantly higher in ΔE₀₀ for each shade (4.16-7.55). The Experimental group had higher ΔE₀₀ for shade B2 (2.70) and A2 (3.01); lower for C2 (1.95) and D3 (3.94). Universal had lower ΔE₀₀ for B2 (0.91) and higher for C2 (3.53) and D3 (5.24).
Conclusions: The reduced shades of Universal and the Experimental group were equivalent to the multi shade Supreme for all five shades. All Omnichroma shades as well as all the darker shades of the other composites exceeded the clinical threshold ΔE₀₀ value (1.8).