Masking discolored substrates with lithium disilicate veneers and resin cements: An in vitro quantitative analysis

Abstract

Objective: This study evaluated how ceramic translucency, resin cement shade, and tooth substrate color influence the masking ability of lithium disilicate veneers, aiming to support evidence-based clinical decision-making.

Methods: IPS e.max CAD ceramics (high, medium, and low translucency) and Variolink Esthetic LC resin cements (four shades) were paired in all combinations and bonded to either A3Dentin (natural dentin, control) or C4Dentin (discolored dentin, experimental) resin composite substrates. Standardized procedures were used for specimen preparation, including hydrofluoric acid etching, silanization, and universal adhesive bonding. Color parameters (L*, a*, b*) were measured using a spectrophotometer, and CIEDE2000 (ΔE₀₀) values were calculated. Data were analyzed via ANOVA, regression, and dominance analysis.

Results: Ceramic thickness affected color outcomes. Substrate shade significantly influenced final color, with Light Plus cement increasing lightness (L*) and blue chroma (b*) values in high-translucency ceramics. Yellow chroma (b*) was more influenced by ceramic translucency. All experimental groups showed ΔE₀₀ values above the clinical acceptability threshold (ΔE₀₀ > 1.8). Substrate shade was the dominant factor affecting color outcomes (87.82 %), followed by ceramic translucency (9.15 %) and cement shade (3.03 %).

Conclusion: No tested combination achieved clinically acceptable masking of severe discoloration. Substrate shade overwhelmingly influenced final color, surpassing ceramic translucency and cement shade. These results emphasize that material selection alone is insufficient and highlight the necessity of substrate modification for optimal esthetic outcomes.

Clinical significance: This study provides clinically applicable guidance for managing the often-unpredictable esthetic outcomes in veneer cases involving tooth discoloration. By quantifying the influence of each variable through dominance analysis within a regression model, the underlying tooth shade was found to contribute approximately 87.82 % to the explained variance in color outcome-emphasizing the importance of substrate modification as a key step toward achieving consistent and natural-looking results. This statistical contribution should be interpreted within the context of the model and not as a clinical absolute.

Keywords: Ceramic translucency; Ceramic veneer; Lithium disilicate ceramic; Masking; Resin cement shade; Tooth discoloration.