Impact of Ceramic Composition and Thickness on Light Transmission in CAD/CAM Lithium Disilicate Materials: An In Vitro Study

This study investigates light transmission through five types of computer-aided design/computer-aided manufacturing (CAD/CAM) lithium disilicate ceramics, varying in thickness (0.50, 1.00, and 1.50 mm). A total of 150 specimens (10 per group) were fabricated using both traditional and novel ceramic materials: E.max CAD (traditional), n!ce Straumann and LiSi Block GC (fully-crystallized), and Amber Mill and Cerec Tessera (precrystallized). After polishing, light transmission was measured using a curing radiometer and surface microstructures were examined with scanning electron microscopy (SEM). The data were analyzed using two-way analysis of variance (ANOVA) with Tukey's post hoc tests. Results revealed that light intensity decreased as the ceramic thickness increased, regardless of the material type. Amber Mill (0.50 mm) exhibited the highest light intensity at 537 mW/cm², followed by E.max CAD (475 mW/cm²) and n!ce Straumann (470 mW/cm²). In contrast, LiSi Block GC (1.50 mm) showed no light transmission (0 mW/cm²), with Cerec Tessera (60 mW/cm²) and E.max CAD (175 mW/cm²) also exhibiting low transmission at 1.50 mm. SEM analysis identified structural differences among the materials. These findings suggest that both the composition and thickness of CAD/CAM lithium disilicate ceramics significantly impact light transmission. Results revealed that material composition and thickness significantly influenced light transmission values, underscoring the importance of selecting appropriate ceramic type and thickness to optimize polymerization during light-cured resin cementation in clinical practice.