Masking of Discolored Backgrounds With Resin Composite Multilayering Technique

Objectives: The aim of this study was to evaluate the effectiveness of the multilayering technique to mask five discolored backgrounds (A3, A3,5, C2, C3 and C4).
Methods: The technique was used with three resin composite systems (IPS Empress Direct, Charisma Diamond and Filtek Z350XT). Forty five 1.5mm-thick specimens were divided into groups and subgroups according to the restorative system and resin composite shade combination used in the layering technique (enamel/dentin, enamel/body/dentin). The color measurements were made over an inherent color background, that represents a tooth without discoloration, and the discolored backgrounds (A3, A3,5, C2, C3 and C4) by a reflection spectrophotometer (SP60, EX-Rite). ΔE was calculated by CIELAB (ΔE_ab) and CIEDE2000 (ΔE₀₀) formulas. Two-way ANOVA and Tukey's post hoc test (α=0.05) were performed to analyze the ΔE_ab and ΔE₀₀ mean values and multiple comparisions.
Results: Lower ΔE values are associated with better masking ability. Clinically acceptable values (ΔE_ab <3.46 and ΔE₀₀ <2.25) were found in the three restorative systems, being the best results with 1.0mm dentin +0.5mm enamel resin composite over A3 and A3,5 backgrounds. None of the combinations of any system presented adequate masking ability upon the C4 background.
Conclusions: Masking ability is influenced by the resin composite restorative system, shade combination of the multilayering technique and severity of the discoloration.