Masking ability of bleach-shade resin composites using the multilayering technique

Evaluate the masking ability of bleach-shade resin composites applied by multilayering techniques over colored substrates.

Disc-shaped specimens were fabricated from bleach-shade resin composites using different multilayering techniques. Substrates were produced in opaque ceramic discs simulating colored substrates (A2, A3, A3.5, C2, C3, C4) and a bleached tooth (0M1). Color coordinates were obtained using a reflectance spectrophotometer. Color difference was calculated by CIEDE2000 using coordinates of 0 M1 ceramic as standard reference. Data were analyzed by one-way ANOVA and Tukey's post-hoc test (p ≤ 0.05). Masking ability interpretation was based on perceptibility and acceptability thresholds.

All combinations presented ΔE₀₀ above the acceptable threshold (ΔE₀₀ >1.8), ranging from 2.49 to 7.42, regardless of the restorative system, multilayering strategy or substrate color. Multilayering combinations placed over A2, A3 and A3.5 were moderately (1.8<ΔE₀₀ ≤3.6) and clearly unacceptable (3.6<ΔE₀₀ ≤5.4), combinations associated with C2, C3 and C4 were clearly unacceptable and, extremely unacceptable (ΔE₀₀ >5.4). Lower ΔE₀₀ was observed for combinations with 0.5 mm extra white enamel layer (2.49), or 1.0 mm white dentin layer (2.69), over A2 and A3.5 substrates. Lightness difference showed the greatest contribution to ΔE₀₀ .

Bleach-shade resin composite systems applied by the multilayering technique were not able to ensure effective masking ability.

Bleach-shade resin composites applied with different combinations of the multilayering technique were not effective in masking colored substrates. Alternative strategies, techniques and dental materials should be explored to obtain acceptable masking.