Shade Variation Influences Color Mismatch in CAD-CAM Lithium Disilicate Crowns Relative to Corresponding Shade Guide

Area of Science:

• Dental Materials Science
• Color Science in Dentistry
• CAD-CAM Technology

Background:

• Accurate color matching is crucial for the esthetic success of dental restorations.
• Computer-Aided Design/Computer-Aided Manufacturing (CAD-CAM) lithium disilicate crowns offer advanced fabrication but require precise shade replication.
• Evaluating color discrepancies between fabricated crowns and shade tabs is essential for clinical predictability.

Purpose of the Study:

• To assess how ceramic shade affects the color matching of CAD-CAM lithium disilicate crowns.
• To compare the color of crowns to their corresponding shade tabs using Commission Internationale de l'Eclairage (CIE) values and nominal shade.
• To evaluate the trueness of color matching methods.

Main Methods:

• A cross-sectional study analyzed CAD-CAM lithium disilicate crowns in VITA Classical shades A3, B3, C3, and D3.
• Color measurements were performed using a spectrophotometer, an intraoral scanner, and visual assessment by nine observers.
• Color differences (ΔEab and ΔE00) were calculated and compared against perceptibility and acceptability thresholds.

Main Results:

• Shade C3 showed the highest mean color difference (ΔEab = 3.42), exceeding the acceptability threshold.
• Color differences (ΔE00) surpassed the acceptability threshold for shades A3, B3, and C3.
• Spectrophotometer trueness was 100% for A3 but 0% for B3 and C3; human assessment demonstrated the lowest reliability.

Conclusions:

• The ceramic shade of CAD-CAM lithium disilicate crowns significantly influences color matching accuracy.
• Shade C3 crowns exhibited the greatest color mismatch, indicating potential esthetic challenges.
• The spectrophotometer demonstrated inconsistency for shades B3 and C3, highlighting limitations in achieving nominal shade accuracy.