Masking ability of layering techniques combined with white or yellow opaquers on a dark background

Clinicians still experience hesitation and uncertainty regarding the techniques required to achieve the appropriate final color for clinical cases involving discolored teeth, and it is often unclear whether a white or yellow opaque shade should be applied. This study evaluated the influence of resin composite (RC) layering techniques, using either regular or flowable opaques in white and yellow shades, on the masking ability of a discolored substrate.

Acrylic upper left central incisors, shade C3, with veneer preparations were divided into 11 groups (n=5). Shade C3 (n=5) and shade A1 (n=5) intact acrylic teeth were the negative and positive control groups, respectively. Teeth were restored with the monolayer, bilayer or trilayer technique, and white or yellow opaques were associated with dentin RC and/or enamel RC. E00 values were obtained using the CIEDE2000 formula. Data were analyzed by Kruskal-Wallis and Dunn's test (=5%).

Groups restored with the trilayer technique (opaque + dentin RC + enamel RC) obtained significantly lower E00 values, below the acceptability threshold. In the trilayer technique, the use of white regular opaque (1.18) did not differ significantly from the positive control (0.69) (p>0.05). The use of yellow opaques increased E00, but it remained below the acceptability threshold.

The trilayer technique using white or yellow opaques, dentin, and enamel RCs yielded E00 values below the acceptability threshold. However, white opaques were more effective in masking the discolored background.