Light Transmission for a Novel Chairside CAD/CAM Lithium Disilicate Ceramic.

Aim: To evaluate light transmission in a novel chairside CAD/CAM lithium disilicate ceramic with different thicknesses and with and without polishing.
Materials and Methods: Sixty flat samples (10 specimens/group) were fabricated from novel chairside CAD/CAM lithium disilicate ceramic blocks (Amber Mill, Hass Bio) with different thicknesses and with and without polishing as follows: (1) 1.0 mm thickness without polishing (1.0NoP); (2) 1.0 mm thickness with polishing (1.0Po); (3) 1.5 mm thickness without polishing (1.5NoP); (4) 1.5 mm thickness with polishing (1.5Po); (5) 2.0 mm thickness without polishing (2.0NoP); and (6) 2.0 mm thickness with polishing (2.0Po). Specimens were polished with a polishing system for lithium disilicate restorations following the manufacturer's recommendations. Light transmission was evaluated with a curing radiometer. Obtained data were subjected to two-way ANOVA followed by Tukey's post hoc tests (α = 0.05). SEM observations were conducted to evaluate surface microstructure.
Results: The light intensity through the lithium disilicate blocks with and without polishing was 200.9 mW/cm ² (16.1%) and 194.4 mW/cm ² (15.6%) for 1.0 mm specimens, 119.3 mW/cm ² (9.5%) and 111.9 mW/cm ² (9.0%) for 1.5 mm specimens, and 102.3 mW/cm ² (8.2%) and 96.0 mW/cm ² (7.7%) for 2.0 mm specimens. SEM images showed a smoother surface with polishing compared to nonpolished specimens.
Conclusion: The thickness and polishing of the restorations were both significant influential factors in light transmission.
Clinical Significance: The range of light transmission percentage through the novel chairside CAD/CAM lithium disilicate blocks was 7.7-16.1%, suggesting that light attenuation through the material may influence the polymerization reaction of resin luting cement in the bonding process.